JPH095932A - Support for photographic materials - Google Patents

Abstract

PURPOSE: To enhance the sharpness of a printed image and to improve preservability to a silver halide photosensitive layer by incorporating a thermoplastic resin and a specified titanium dioxide pigment into a thermoplastic resin layer. CONSTITUTION: Paper based on natural pulp is used as a base and one face of the paper base on which a photographic image forming layer is disposed is coated with a thermoplastic resin (A) layer to obtain the objective substrate. The thermoplastic resin (A) layer contains at least the thermoplastic resin (A) and a titanium dioxide pigment produced by spray-drying and having >=0.32g/cm<3> apparent density (stationary method) measured in accordance with JIS K5101-1991.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a paper mainly composed of natural pulp as a substrate, and one of the paper substrates (hereinafter sometimes simply referred to as base paper) on the side on which the photographic image forming layer is provided. The present invention relates to a support for a resin-coated paper-type photographic material, which is coated with a thermoplastic resin layer, and the base paper surface on the opposite side is preferably coated with a resin capable of forming a film, and more specifically, relates to the sharpness (sharpness) of a printed image. ) Is high, and the storage stability for the silver halide photosensitive layer is remarkably improved,
Moreover, an excellent resin-coated support for paper-type photographic material, which is capable of providing a photographic material in which peelability from a cooling roll during the production of the support is remarkably improved and uneven peeling does not occur, and therefore gloss is good. It is about.

[0002]

2. Description of the Related Art Conventionally, a resin-coated support for paper-type photographic materials in which a base paper surface containing natural pulp as a main component is coated with a thermoplastic resin layer is well known. For example, Japanese Examined Patent Publication (Kokoku) No. 55-12584 discloses a technique for a support for a photographic material in which a base paper is coated with a resin capable of film-forming, preferably a polyolefin resin. U.S. Pat. No. 3,501,298 discloses a technique for a photographic material support in which both sides of a base paper are coated with a polyolefin resin.
Since the rapid photographic processing method for silver halide photographic light-sensitive materials was applied, a support for photographic materials in which both sides of a base paper were coated with a polyethylene resin was mainly put into practical use for photographic printing paper. However, a titanium dioxide pigment is usually contained in the resin layer on the side on which one of the photographic image forming layers is provided, if necessary, in order to impart sharpness.

Conventionally, anatase type and rutile type titanium dioxide pigments are known as titanium dioxide pigments to be contained in the resin layer on the photographic image forming side of the resin-coated paper type photographic material support. Further, the surface of titanium dioxide particles is not coated with titanium dioxide, or the surface of titanium dioxide particles as described or exemplified in JP-A-52-35625 and JP-A-57-108849 is hydrous. Titanium dioxide pigment coated with a hydrous metal oxide such as aluminum or hydrous silicon oxide, and further disclosed in JP-A-52-3
The surface of titanium dioxide particles as described or exemplified in Japanese Patent Publication No. Titanium dioxide pigments which are coated with substances are known.

On the other hand, when a particularly high sharpness (sometimes called sharpness) of a printed image is required for photographic materials, some resin-coated paper-type photographic material supports are also known. ing. For example, (1) a resin layer containing a titanium dioxide pigment at a high concentration,
(2) A titanium dioxide pigment in the resin layer, which contains a rutile type pigment, and (3) zinc stearate, calcium stearate, zinc palmitate, etc. as described in JP-B-58-43734. A resin layer containing a titanium dioxide pigment by adding a surfactant typified by metal soap, (4) As the titanium dioxide pigment in the resin layer, the particle surface is coated with the organic substance as described above. Known products are those containing a so-called organically treated titanium dioxide pigment which has been treated.

However, these resin-coated supports for paper-type photographic materials have insufficient sharpness as intended, and have some serious problems with respect to other photographic suitability and manufacturing suitability. However, the actual situation is that satisfactory results have not been obtained yet.

First, when the concentration of the titanium dioxide pigment in the resin layer of the resin-coated paper-type photographic material support is increased, a photographic-material support having a sharp print image can be obtained. Significant photographic and manufacturing suitability problems often occur. That is, the side of the base paper on which the photographic image forming layer is provided (hereinafter, the side on which the photographic image forming layer is provided is the front side, the resin layer coated on the front side is the front resin layer, the opposite side is the back side, and the resin layer coated on the back side is The resin-coated paper for use as a support for photographic materials whose surface is coated with a thermoplastic resin layer containing a titanium dioxide pigment, particularly a polyethylene-based resin layer, is usually on a base paper that runs. Using a melt extrusion machine containing a thermoplastic resin composition containing titanium dioxide pigment, the film is cast from its slit die to be coated, pressure-bonded between a pressure roll and a cooling roll, and after cooling from the roll. It is manufactured by a series of steps of peeling. However, when a thermoplastic resin composition containing a titanium dioxide pigment, especially a polyethylene resin composition is melt-extruded and coated on a base paper in a film form from a slit die, the releasability of the resin-coated paper from the cooling roll is deteriorated. However, lateral unevenness in the width direction, which is referred to as peeling unevenness, occurs on the resin-coated paper surface.

Therefore, as a result of various investigations by the inventor of the present invention, the occurrence of peeling unevenness was found to be caused by the type and properties of the thermoplastic resin composition containing the titanium dioxide pigment, particularly the polyethylene resin composition, especially the thermoplastic resin composition. Depends largely on the type, properties, content, etc. of the titanium dioxide pigment contained in the resin composition, and peels off even if the previously known titanium dioxide pigment as described above is contained in the thermoplastic resin composition. It turned out that the unevenness could not be improved. Also,
The thicker the surface resin layer of the resin-coated paper, especially 15 μm or more, and the faster the production speed of the resin-coated paper, specifically 100 m / min or more, particularly 150 m / min or more. In the case of, it was found that the releasability of the resin-coated paper from the cooling roll deteriorates. Originally, it has a mirror surface or a glossy surface or a finely rough surface described in JP-B-62-19732.
Although resin-coated papers for photographic materials for glossy use are required to have a high degree of smoothness, when this peeling unevenness occurs, the photographic material using the resin-coated paper as a support also suffers from uneven gloss, resulting in inferior glossiness. Since only the material can be obtained, there is a problem that the material is completely unsuitable as a photographic material for glossy and has no commercial value.

Second, when a rutile type titanium dioxide pigment is used as the titanium dioxide pigment contained in the surface resin layer of the resin-coated paper-type photographic material support, it is compared with the case where an anatase type is used. Thus, although a support for photographic material having a considerably high sharpness of a printed image can be obtained, another serious problem in photographic suitability occurs. That is, the resin surface containing the titanium dioxide pigment on the photographic image forming side of the photographic material support has a yellowish color due to the rutile titanium dioxide pigment,
There is a problem that a support for photographic materials having a clear whiteness cannot be obtained.

Thirdly, as a result of the study by the present inventors, when a titanium dioxide pigment is contained in a surface resin layer of a resin-coated paper-type photographic material support, particularly in a polyolefin resin layer,
Even if a surfactant represented by a metal soap such as zinc stearate, calcium stearate, or zinc palmitate is added, the sharpness of the printed image of the support for photographic materials is
It turns out that there is a problem that it is not substantially high.

Generally, as a method of incorporating the titanium dioxide pigment into the surface resin layer of the support for resin-coated paper-type photographic material, a usual melt-kneading machine such as a Banbury mixer, a kneader, and a kneading extruder is used. Create a so-called masterbatch in which the pigment is contained in the resin in high concentration in advance,
A thermoplastic resin composition obtained by diluting and mixing it in a desired ratio with a diluting resin is melt-extruded or coated, or a so-called compound is prepared in which the pigment is contained in the resin only at a desired composition ratio from the beginning, and melt-extrusion coating is performed. It is usually done.
Further, the main purpose of the metal soap originally added to the surface resin layer of the resin-coated paper-type photographic material support is to prepare a melt extruder when the photographic material support is produced by melt extrusion coating. It is to improve the peelability between the cooling roll and the resin-coated surface.

However, as a result of the study by the present inventor, new findings have been found regarding the effect of the metal soap in the surface resin layer. That is, the concentration of metal soap added when preparing a masterbatch or compound of titanium dioxide pigment in the surface resin layer of the support for resin-coated paper-type photographic material is 1.5% by weight based on titanium dioxide pigment. And, the sharpness of the printed image of the support for photographic materials increases up to 0.15% by weight with respect to the resin composition, but with this content, the releasability is poor, and with respect to the titanium dioxide pigment. When the content is in the range of 1.5% by weight to 7.5% by weight, and 0.15% by weight to 0.75% by weight based on the resin composition, the releasability is improved with the addition amount. It has been found that the sharpness of the printed image of the photographic material support is considerably lower, sometimes lower than in the absence of metallic soap.

Further, when the content is more than that, the sharpness of the printed image of the support for photographic materials gradually decreases with the addition amount, and the generation of oily smoke increases, and the sharpness at the time of melt extrusion coating is increased. It was found that the suitability for production was extremely poor. As described above, even when a metal soap is added when the titanium dioxide pigment is compounded in the surface resin layer of the resin-coated paper-type photographic material support, a photographic material support having a high print image sharpness can be obtained. There was a problem that I could not.

Fourthly, as a result of the study by the present inventors, as a titanium dioxide pigment to be contained in the surface resin layer of the resin-coated support for paper-type photographic materials, particularly in the polyolefin resin layer,
It has been found that there is a problem that the so-called sharpness of the printed image of the support for photographic materials is not substantially high even when the so-called organically treated titanium dioxide pigment is used. That is, a metal soap represented by zinc stearate or the like together with an organically treated titanium dioxide pigment is provided in the surface resin layer of a resin-coated paper-type photographic material support to exhibit sufficient releasability during the production of the photographic material support. It was found that when added up to the amount, the sharpness of the printed image of the support for photographic material is almost the same as that of the case where a titanium dioxide pigment not subjected to organic treatment is used. .

Fifth, halogenation using a resin-coated paper obtained by coating the front side of a base paper mainly composed of natural pulp with a titanium dioxide pigment-containing thermoplastic resin, particularly a polyolefin resin composition, as a support. In the case of silver photographic materials, when they are stored after their production, they are stored for a long period of time, and especially when they are stored under high temperature and high humidity, the unexposed parts of the photographic materials called fog can be developed during development processing. However, there is a problem that the sensitivity of the photographic material is unduly increased or decreased. In addition, there is also a problem that the tone of the photographic material is changed to soften the tone.

Therefore, as a result of various studies on the factors, the present inventor has found that the change in photographic characteristics of the silver halide photographic material having this resin-coated paper as a support, that is, the so-called storability of the silver halide photographic material is titanium dioxide. A thermoplastic resin composition containing a pigment, particularly a polyolefin resin composition, especially the type and properties of a polyethylene resin composition, especially the type of titanium dioxide pigment to be contained in the thermoplastic resin composition,
It is greatly dependent on properties, content, etc., and it is not possible to improve the storability of the silver halide photographic material even if the above-mentioned conventionally known titanium dioxide pigment is contained in the thermoplastic resin composition. found.

Conventionally, there have been some technical proposals for improving the releasability of thermoplastic resin-coated paper for use as a support for photographic materials, particularly polyethylene-based resin-coated paper. As a typical method for improving the releasability during the production of polyethylene-based resin-coated paper, it has been proposed to incorporate various release agents into the polyethylene-based resin composition. For example, a specific fatty acid amide described in JP-A-60-176036, 63
-30841 gazette polyalkylene glycol compound, the fluorine-containing polymer described in the same 64-9444 gazette, various releasing agents such as α-olefin modified silicone described in JP-A-4-143748 have been proposed. There is. However,
Even if these release agents are contained in the polyethylene resin composition, the effect of improving their releasability is extremely insufficient,
At a production speed of 100 m / min or more, particularly 150 m / min or more, there is little or no effect, and on the contrary, the adhesiveness between the base paper and the polyethylene resin layer deteriorates, or it is coated on the polyethylene resin coated paper. There is a problem that the adhesiveness between the photosensitive layer or the photographic image forming layer and the polyethylene resin layer deteriorates.

Another attempt to improve the releasability during the production of polyethylene resin-coated paper is disclosed in Japanese Examined Patent Publication No. 62-19732.
Use of a chilled roll with a micro-roughened surface described in Japanese Patent Publication
Use of a cooling roll in which a fluororesin described in 1-24292 is embedded, and further, a melting peak described in JP-A-1-129249 is 110 ° C. or higher, and a melt index is 5 to 20 g / Use of low-density polyethylene resin for 10 minutes, low-density polyethylene resin described in JP-A-6-242549 with an extraction amount of hexane of 3% by weight or less, and titanium dioxide having an oxidation induction period of 70 to 1000 seconds. Techniques for combined use of pigment resin compositions have been proposed.
However, even if these cooling rolls and resins are used, the effect of improving the releasability of the polyethylene-based resin-coated paper is insufficient, and the effect of improving releasability at a production rate of 100 m / min or more, particularly 150 m / min or more. Was quite inadequate.

On the other hand, there are some proposals for improving the storability of a silver halide light-sensitive material having as a support a paper, particularly a resin-coated paper whose substrate is a paper mainly composed of natural pulp. Japanese Patent Publication No. 49-30446 and Japanese Patent Publication No. 50-33652 disclose that the photosensitive layer is provided on the side where the photosensitive layer is formed because the decomposition products and oxides of the resin produced during melt extrusion coating cause fog in the emulsion of the photographic paper. There is proposed a support for a resin-coated paper type photographic paper, which has a double-layered resin layer, and an upper resin layer adjacent to the photosensitive layer is melt-extrusion coated at a low temperature to reduce fog. However, in the silver halide light-sensitive material having the support, not only the storage stability is extremely insufficient, but also the fluidity of the resin layer becomes unstable because the temperatures of the two-layer resin composition are different, and molding processing is performed. The sex was extremely insufficient. In addition, Tokiko Sho 54
JP-A-99884 proposes a fog-preventing resin-coated paper-type photosensitive material support comprising a base paper coated with a polyolefin resin containing a hydroxy-substituted-triazolopyrimidine compound. Even if the body is used, the improvement of the storage stability of the silver halide light-sensitive material has been quite insufficient.

Regarding photographic paper, Japanese Patent Laid-Open No. 52-65423
Japanese Patent Publication No. 58-43730 and Japanese Patent Publication No. 58-43730 propose to remove the adverse effects on the photographic properties due to the decomposition of cationic electrolytes and chemicals for paper, respectively. Even when used as a body, the storability of the silver halide photographic material could not be improved at all, and it became clear that the deterioration of the storability was caused by a mechanism completely different from the mechanism described in these specifications.

As described above, the resin-coated paper type photographic material support in which the surface of the base paper containing natural pulp as the main component on the side where the photographic image forming layer is provided is coated with a thermoplastic resin layer, particularly a polyethylene resin layer. There is no known method for improving the sharpness of the printed image of the resin without impairing the other performances of the support and the moldability during the production of the support, and from the cooling roll during the production of the resin-coated paper type support. The mechanism for causing the peeling mechanism and uneven peeling, and the mechanism or the cause of deterioration of the storage stability of the silver halide photographic material having the support are not known.

[0021]

SUMMARY OF THE INVENTION Therefore, the first object of the present invention is to provide a sharpness of a printed image in which the base paper side on which the photographic image forming layer is provided is coated with a thermoplastic resin layer containing a titanium dioxide pigment. And the storability for the silver halide photosensitive layer is remarkably improved, and the releasability from the cooling roll during the production of the support is remarkably improved, and no peeling unevenness occurs, and therefore the gloss is excellent. Another object of the present invention is to provide a resin-coated support for paper-type photographic materials, which can provide such photographic materials. A second object of the present invention is to provide a thermoplastic resin layer containing a titanium dioxide pigment on the side of the base paper on which the photographic image forming layer is provided.
It is coated at a production rate of 00 m / min or more, particularly 150 m / min or more, and therefore has good productivity and excellent economical efficiency, and the peelability from the cooling roll is remarkably improved to prevent the occurrence of peeling unevenness. Therefore, there is provided a support for a resin-coated paper type photographic material, which can provide a photographic material having excellent glossiness, a high sharpness of a printed image, and a remarkably improved storability for a silver halide photosensitive layer. That is. Other objects of the present invention will become clear from the description of the following specification.

[0022]

As a result of intensive studies to solve the above problems, the present inventor has found that paper containing natural pulp as a main component is used as a substrate and one of the paper substrates provided with a photographic image forming layer is provided. In a support for a photographic material, the surface of which is coated with a thermoplastic resin (A) layer, the thermoplastic resin (A) layer contains at least a thermoplastic resin and a titanium dioxide pigment, and the titanium dioxide pigment is spray-dried. And a manufactured photographic material support having an apparent density (static method) of 0.32 g / cm ³ or more, which is obtained in accordance with JIS K 5101-1991. It has been found that the objects of the present invention are achieved.

An object of the present invention is to provide a support for photographic materials, which comprises a base paper containing natural pulp as a main component, the paper substrate surface of which is provided with a photographic image forming layer, coated with a thermoplastic resin (A) layer. The thermoplastic resin (A) layer contains at least a thermoplastic resin and a titanium dioxide pigment, and is produced by spray-drying as a titanium dioxide pigment, and is determined in accordance with JIS K 5101-1991. It was found that synergistic effects can be achieved by using those having an apparent density (static method) of 0.32 g / cm ³ or more. Further, the object of the present invention is as a titanium dioxide pigment, the surface of which is calculated in the form of anhydrous metal oxide per titanium dioxide of 0.25% by weight to 1.5% by weight, particularly 0.35% by weight.
It has been found that this is remarkably achieved by using 1.25% by weight of a specific hydrous metal oxide, especially one surface-treated with at least aluminum hydroxide. Also,
The object of the present invention is to use a titanium dioxide pigment having a particle size of 0.110 to 0.150 μm, which is represented by the number average diameter in the direction measurement by an electron microscope.
I have found that it can be achieved significantly. Further, the object of the present invention was found to be more remarkably achieved by using a titanium dioxide pigment having an anatase structure produced by an external seed method, and the present invention has been completed.

More specifically, the spray-drying of titanium dioxide pigment is disclosed in JP-A-3-50120, but it is simply spray-dried into the surface resin layer of the resin-coated paper-type photographic material support. The effect of the present invention is not obtained at all even if it contains a titanium dioxide pigment produced by the above, as a titanium dioxide pigment, it is produced by spray drying,
Further, the object of the present invention is synergistically achieved by including in the surface resin layer those having an apparent density (static method) of 0.32 g / cm ³ or more, which is determined in accordance with JIS K 5101-1991. That is, the present invention has been achieved.

The base paper surface of the support for photographic materials according to the present invention on the side where the photographic image forming layer is provided is covered with a thermoplastic resin layer containing at least the thermoplastic resin (A) and the titanium dioxide pigment according to the present invention. Those thermoplastic resins (A)
As the polyolefin resin, a polyester resin, a polycarbonate resin, a polyamide resin or a mixture thereof is preferable, and among them, a polyolefin resin, a polyester resin or a mixture thereof is more preferable from the viewpoint of melt extrusion coating property, and a polyethylene resin is preferable. Resins are particularly preferred. As the polyethylene-based resin particularly preferably used in the practice of the present invention, low-density polyethylene resin, medium-density polyethylene resin, high-density polyethylene resin, linear low-density polyethylene resin, ethylene and propylene, α-olefins such as butylene So-called carboxy-modified polyethylene resin, which is a copolymer, a copolymer of ethylene and acrylic acid, acrylic acid ethyl ester, maleic anhydride, or the like, or a graft copolymer, as well as an autoclave type reactor, a tubular type reactor, etc. Polyethylene resin produced by high-pressure radical polymerization method, polyethylene resin produced by polymerization using metallocene polymerization catalyst, Ziegler method, polyethylene resin produced by polymerization using metal catalyst other than metallocene by Phillip method, etc. It is a mixture of various densities and -Flow rate (hereinafter, abbreviated simply as MFR to a melt flow rate specified by JIS K 6760), the molecular weight, can be used those having a molecular weight distribution, typically, density of 0.90~0.97g / cm ³ Range, MFR 0.1g / 10min ~
50g / 10min, preferably MFR 0.3g / 10min-40g
Those in the range of / 10 minutes can be advantageously used alone or as a mixture. When the surface resin layer has a multi-layer structure, the outermost resin has, for example, an MFR of 5 g / 10 minutes to 20 g / 10 minutes, and the lower resin has, for example, an MFR of 2 g / 10 minutes to 1
It is also possible to use a resin having a different property and constitution, such as using 0 g / 10 min. Also, a multilayer structure may be used in which only the outermost layer is a resin layer containing the specific titanium dioxide pigment in the present invention.

The polyester resin used in the practice of the present invention includes polyethylene terephthalate resin, polybutylene terephthalate resin, polyester biodegradable resin and the like, and mixtures thereof, which have various densities, molecular weights and viscosities. However, a copolymerized polyethylene terephthalate resin is preferable from the viewpoint of melt extrusion coating property. As a specific representative example, a copolyester resin manufactured by Eastman Chemical Japan Co., Ltd. [trade name: Koder PETG 676
3: Density 1.27 g / cm ³ , glass transition point approx. 81 ° C., average molecular weight (Mn) approx. 26 million] and thermoplastic polyester resin [trade name: Kodapak-PET 298L
B] and the like.

The surface of the base paper of the support for photographic materials in the present invention opposite to the side where the thermoplastic resin (A) layer is provided is preferably covered with a resin (B) layer capable of forming a film. As the resin (B) capable of forming a film,
Polyolefin resin, polyester resin, polycarbonate resin, a thermoplastic resin such as a polyamide resin or a mixture thereof is preferable, and among them, a polyolefin resin, a polyester resin or a mixture thereof is more preferable from the viewpoint of melt extrusion coating property, Polyethylene resins are particularly preferred. In addition, Japanese Examined Sho 60-17104
It may be coated with an electron beam curable resin layer described or exemplified in the publication.

The titanium dioxide pigment used in the practice of the present invention is produced by spray drying, and the apparent density (static method) required in accordance with JIS K 5101-1991 [hereinafter referred to as JIS The term "apparent density (static method)" required in accordance with K 5101-1991 is
Any of rutile structure, anatase structure, chlorine method, and sulfuric acid method can be used as long as it is simply referred to as apparent density] of 0.32 g / cm ³ or more. In the case of the chlorine method, titanium dioxide particles are formed by vapor-phase oxidative decomposition of titanium tetrachloride at a high temperature in the case of the chlorine method, and a rutile structure is generally easily obtained. In the case of the sulfuric acid method, hydrous titanium oxide is formed by hydrolysis of an aqueous solution of titanyl sulfate and is fired to develop its pigmentary properties. In the case of the sulfuric acid method, both of anatase structure and rutile structure can be obtained, but in the case of producing a rutile structure, the firing temperature is higher than that of anatase structure, or firing is performed. At times, a metal compound such as a zinc compound for promoting the formation of the rutile structure is allowed to coexist. The product formed by calcination or oxidation will be referred to as a titanium dioxide clinker hereinafter. Titanium dioxide clinker is dry pulverized in a centrifugal roller mill (mainly Raymond mill), the pulverized product is suspended in water to form a titanium dioxide slurry, and then wet pulverized in a wet ball mill or vibration mill, and continuous horizontal centrifugal separation. Machine and / or through a vibrating double deck screen (325 mesh U.S. standard screen) for wet classification, subsequently referred to as fines, a substantially coarse-grained dioxide. Use titanium dioxide slurry without titanium. For fines with coarse particles removed and still in the form of a slurry, the surface of titanium dioxide particles is preferably surface-treated with a hydrous metal oxide in a reaction treatment tank equipped with a stirrer. After the surface treatment, it is preferably filtered with a filter press and washed with water. After washing with water, the titanium dioxide cake is taken out from the filter press to form a titanium dioxide slurry in a water tank, and then spray dried by a spray dryer. Further, fine pulverization with an impact pulverizer or / and a fluid energy mill, preferably a steam mill, is carried out to produce a titanium dioxide pigment. The fluid energy is preferably equipped with a bag filter.

The titanium dioxide pigment used in the practice of the present invention is produced by spray drying. As a spray drying device, in principle, a titanium dioxide slurry is sprayed into an evaporation pipe on a hot air flow path through a two-fluid nozzle,
At the same time as entraining the atomized titanium dioxide slurry with hot air heated by an electric heater, a steam heater, etc., it significantly increases the evaporation area, and therefore evaporates water in a short time to form a dry fine powder, Various devices can be used as long as they are devices in which the fine powder is guided to a cyclone (collection part). Further, an apparatus using ultrasonic waves as the spraying means and an apparatus using microwaves as the drying means can also be used. After spray drying, additional drying can be performed.

The titanium dioxide pigment used in the practice of the present invention is produced by spray drying and has an apparent density of 0.32 g / cm ³ or more, but the sharpness of the printed image ( From the viewpoint of significantly improving the sharpness), the storage stability of the silver halide photographic material, and the releasability from the cooling roll during the production of the resin-coated paper, the apparent density is 0.35 g. / cm ³ or more ones are preferred, 0.38 g / cm ³ or more is particularly preferable.

The titanium dioxide pigment used in the practice of the present invention, which is produced by spray-drying and has an apparent density of 0.32 g / cm ³ or more, is specifically described below.
By the use of the method described in (5), it was revealed by the study of the present inventor that the method is preferably obtained by combining two or more of the following methods, more preferably three or more.

(1) In producing a titanium dioxide pigment,
Optimize spray drying of titanium dioxide slurry. In order to optimize the spray drying conditions of the titanium dioxide slurry, it can be appropriately determined depending on the type of spray drying device. Specifically, the apparent density is 0.32 g / cm ³ or more and the particle size is uniform and fine. It is possible to optimize the conditions such as the spraying amount of titanium dioxide slurry, the spraying pressure, the size of sprayed droplets, the temperature of hot air, and the drying time so that a dry fine powder is obtained.

(2) As a titanium dioxide pigment, the surface of the particles thereof has a silicon dioxide content of at least aluminum atoms of 0.25 to 1.5% by weight calculated as anhydrous metal oxide per titanium dioxide. As the material, one treated with a hydrous metal oxide of 0.4% by weight or less (including 0) is used. If the amount of titanium dioxide surface treated is less than 0.25% by weight, the apparent density of the titanium dioxide pigment tends to be low, and the titanium dioxide pigment is contained in the surface resin layer of the resin-coated support for paper-type photographic materials. Shows poor print image sharpness, poor storage stability for the silver halide photosensitive layer, and poor peelability from the chill roll during the production of resin-coated paper, effectively preventing uneven peeling. I can't do it. On the other hand, when the treatment amount is more than 1.5% by weight, the apparent density of the titanium dioxide pigment tends to be gradually decreased as the amount is increased. The support has insufficient sharpness and storability of the printed image, and the peelability from the cooling roll during the production of the resin-coated paper is poor, so that uneven peeling cannot be effectively prevented. It's a problem. The preferable range of treatment amount is 0.35% by weight to 1.25% by weight, particularly preferably 0.5% by weight to 1.25% by weight, calculated as anhydrous metal oxide with respect to titanium dioxide. %
Range. The silicon dioxide content containing at least aluminum atoms and 0.4% by weight or less (including 0) of the hydrous metal oxide is preferably surface-treated with hydrous aluminum oxide, and if necessary, as the silicon dioxide content. 0.4% by weight or less, preferably 0.25% by weight
Less than 0.5% by weight of hydrous silicon oxide or other hydrous metal oxide such as hydrous titanium oxide can be used in the total amount of anhydrous metal oxide.

(3) As the titanium dioxide pigment, one having a particle diameter in the range of 0.110 μm to 0.150 μm, expressed as the number average diameter in the direction measurement by an electron microscope, is used. In the present specification, the number average diameter in the directional measurement by an electron microscope (the term "number average diameter in the directional measurement by the electron microscope may be simply abbreviated as the number average diameter" hereinafter) means titanium dioxide. The length of the pigment particle is a value obtained by averaging the lengths of 1000 particles by directional measurement with an electron microscope, and is expressed in μm. When the number average particle diameter of the titanium dioxide pigment is 0.110 μm or less, the smaller the number average particle diameter, the lower the apparent density of the titanium dioxide pigment tends to be, and the resin containing the titanium dioxide pigment in the surface resin layer. The coated paper type photographic material support tends to have poor sharpness of a printed image and storability with respect to a silver halide photosensitive layer, and also tends to have poor releasability from a cooling roll during the production of a resin-coated paper. Uneven peeling cannot be effectively prevented. On the other hand, a resin-coated support for paper-type image material containing a titanium dioxide pigment larger than 0.150 μm in the surface resin layer tends to have a considerably low sharpness of the printed image.

As a result of various studies by the present inventor, the titanium dioxide pigment finally obtained by the combined use of titanium dioxide having a number average diameter of 0.110 μm to 0.150 μm and spray drying, has a synergistic effect. It has been found that the apparent density can be increased and the sharpness of the printed image, the storability with respect to the silver halide photosensitive layer, and the releasability from the cooling roll during the production of the resin-coated paper can be significantly improved. Therefore, the titanium dioxide pigment used in the practice of the present invention has a number average diameter of 0.110 μm to 0.10 μm.
The range of 150 μm is preferable, and 0.115 μm to 0.1
The range of 35 μm is particularly preferable.

(4) Titanium dioxide pigments produced by the external seed method, particularly preferably by the external seed method and having a number average diameter of 0.110 μm to 0.150.
A titanium dioxide pigment with anatase structure in the range of μm is used. Here, the titanium dioxide pigment having an anatase structure (hereinafter, may be simply referred to as anatase titanium dioxide pigment) is 90% by weight or more in its crystal structure,
Preferably, 95% by weight or more has an anatase structure. By using the anatase type titanium dioxide pigment, it is possible to obtain a support for a photographic material, which has a high sharpness of a printed image and an excellent whiteness.

Conventionally, the production method of titanium dioxide is usually to separate iron sulfate from a solution obtained by treating ilmenite with sulfuric acid,
When the separated titanyl sulfate solution is boiled and hydrolyzed, the titanyl sulfate solution is added to warm water, and titanium hydroxide is deposited to form seeds. It is difficult to control the production conditions such as the concentration of the titanyl solution, the temperature and the time during hydrolysis, and the apparent density of the titanium dioxide pigment finally obtained tends to be low, and this tendency is particularly remarkable for the anatase titanium dioxide pigment. Met. On the other hand, the titanium dioxide pigment produced by the external seed method referred to in the present invention is a titanium water prepared by neutralizing titanyl sulfate or titanium tetrachloride separately when hydrolyzing by boiling a titanyl sulfate solution. It refers to a titanium dioxide pigment produced by the method of adding an oxide as a seed. In the case of the titanium dioxide pigment produced by the external seed method as referred to in the present invention, there is an advantage that titanium dioxide having a desired particle diameter and a uniform particle size distribution can be freely produced. As a result of the examination, by combining the external seed method and the spray drying,
Due to the synergistic effect of them, the apparent density of the titanium dioxide pigment finally obtained can be increased. In particular, the improvement of the apparent density is achieved by the number average diameter of 0.110 μm to 0.10 μm.
It was found that the anatase type titanium dioxide pigment having a particle size of 150 μm is remarkable.

(5) As the titanium dioxide pigment, it is preferable to use a so-called organic surface-treated titanium dioxide pigment whose surface is treated with an organic substance. Specifically, it is 0.05% by weight based on titanium dioxide with a silane coupling agent, an organopolysiloxane compound, an alkanolamine compound, etc. described or exemplified in JP-B-60-3430 and JP-B-61-26652. Preference is given to using titanium dioxide pigments which have been surface treated to ˜4.0% by weight. If the surface treatment amount is less than 0.05% by weight, the effect of the organic surface treatment is small, and if it is more than 4.0% by weight, the peelability from the cooling roll during the production of the resin-coated paper is deteriorated, which is another problem. As a result, the adhesiveness between the surface resin layer and the photographic image forming layer, particularly the film-forming property during the development processing of the photographic material is deteriorated, which is a problem.

As a result of various studies by the present inventor, the preferable amount of the organic surface treatment is in the range of 0.05% by weight to 4.0% by weight with respect to titanium dioxide. In this range, the organic surface treatment and the spray drying are performed. When used in combination, the apparent density of the titanium dioxide pigment finally obtained can be increased by their synergistic effect, and the sharpness of the printed image, the storability to the silver halide photosensitive layer and the production of resin-coated paper It was found that the releasability from the chill roll can be remarkably improved. The most preferable surface treatment amount is in the range of 0.3% by weight to 2.0% by weight with respect to titanium dioxide.

As a result of various studies by the present inventor, as a preferred embodiment of the present invention, as a titanium dioxide pigment to be contained in the surface resin layer of the resin-coated paper-type photographic material support, the surface thereof is anhydrous per titanium dioxide. Treated with 0.25 to 1.5% by weight, more preferably 0.35 to 1.25% by weight, calculated in the form of the metal oxide, of a hydrated metal oxide containing at least aluminum atoms. And produced by spray drying, the apparent density is 0.35 g / cm ³
The above is to use the titanium dioxide pigment.

In a further preferred embodiment of the present invention, the titanium dioxide pigment contained in the surface resin layer of the resin-coated paper-type photographic material support has a surface in the form of anhydrous metal oxide per titanium dioxide. Treated with 0.25 wt% to 1.5 wt%, more preferably 0.35 wt% to 1.25 wt% of hydrous metal oxide containing at least aluminum atoms, and number averaged A titanium dioxide pigment having a diameter of 0.110 μm to 0.150 μm and having an apparent density of 0.35 g / cm ³ or more, which is produced by spray drying.

In a more preferred embodiment of the present invention, the titanium dioxide pigment contained in the surface resin layer of the resin-coated paper-type photographic material support has a surface in the form of anhydrous metal oxide per titanium dioxide. An organic surface treated with 0.25 wt% to 1.5 wt%, more preferably 0.35 wt% to 1.25 wt% hydrated metal oxide containing at least aluminum atoms, calculated Treated and number average diameter is from 0.110 μm to 0.150
The use is made of a titanium dioxide pigment having an apparent density of 0.38 g / cm ³ or more, which is produced by further spray drying.

In a preferred embodiment of the present invention, the titanium dioxide pigment contained in the surface resin layer of the resin-coated paper-type photographic material support is calculated in the form of anhydrous metal oxide on the surface per titanium dioxide. 0.25% by weight to 1.5% by weight, more preferably 0.35% by weight
Treated with 1.25% by weight of a hydrous metal oxide containing at least aluminum atoms and having a number average diameter of 0.1
Anatase type titanium dioxide pigment having an apparent density of 0.35 g / cm ³ or more, which is 10 μm to 0.150 μm, and which is produced by the external seed method and further produced by spray drying.

In a more preferred embodiment of the present invention, the titanium dioxide pigment contained in the surface resin layer of the resin-coated paper-type photographic material support has a surface in the form of anhydrous metal oxide per titanium dioxide. An organic surface treated with a calculated 0.25% to 1.5% by weight, even more preferably 0.35% to 1.25% by weight of a hydrated metal oxide containing at least aluminum atoms. Treated and number average diameter is from 0.110 μm to 0.150
The use of anatase titanium dioxide pigment having an apparent density of 0.35 g / cm ³ or more, which is produced by further spray drying.

In a further preferred embodiment of the present invention, the surface of the titanium dioxide pigment contained in the surface resin layer of the resin-coated support for paper-type photographic material is a form of anhydrous metal oxide per titanium dioxide. Calculated with 0.3
5% by weight to 1.25% by weight, particularly preferably 0.35% by weight to 1.25% by weight, treated with a hydrated metal oxide containing at least aluminum atoms, and treated with an organic surface, and in number Average diameter is 0.110μm ~ 0.15
0 μm, further produced by external seeding method, further produced by spray drying, apparent density is 0.38 g / c
The use of anatase-type titanium dioxide pigment with m ³ or more.

The titanium dioxide pigments preferably used in the practice of the present invention have a particle surface of at least 0.25% to 1.5% by weight of at least aluminum atoms, calculated as anhydrous metal oxides per titanium dioxide. It is produced by treating with a hydrous metal oxide containing 0.4% by weight or less (including 0) as a silicon dioxide content. A specific example of the method for treating the surface of the titanium dioxide particles with the hydrous metal oxide is a titanium dioxide slurry, preferably fine p
After adjusting H to 5 or more, preferably 6 or more, particularly preferably around 7, a water-soluble aluminum salt and, if necessary, other water-soluble metal salt or water-soluble silicon compound are added to the titanium dioxide slurry, and the slurry in the slurry is continuously added. By changing the pH,
The hardly soluble aluminum oxide hydroxide and, if necessary, other hardly soluble hydroxide and / or hardly soluble metal compound can be precipitated on the titanium dioxide particles for surface treatment. For example, a typical method for surface treatment in a reaction tank equipped with a stirrer is described. Titanium dioxide slurry, preferably fine caustic soda, and an aqueous solution of a water-soluble alkali such as potassium hydroxide are added to form a slurry. PH of the solution is adjusted to 7.0 ± 1.0. To the pH-adjusted titanium dioxide slurry, an aluminate such as an alkali aluminate, and if necessary, an aqueous solution of a water-soluble alkali such as sodium hydroxide and potassium hydroxide is added, and then the pH of the slurry exhibiting alkalinity is increased. In order to reduce the amount of water and to precipitate the hydrous aluminum oxide on the surface of the titanium dioxide particles, a surface treatment is performed by adding an aqueous solution of a mineral acid such as sulfuric acid or hydrochloric acid or a salt exhibiting an acidic reaction. The pH of titanium dioxide slurry after surface treatment is usually 7.0 ±
The range is 1.0. Among the alkali aluminates, sodium aluminate is particularly useful. Further, in addition to the aluminate, it can be surface-treated with another inorganic surface-treating agent. In this case, it can be added at any stage before, during or after the addition of the aluminate, but it is particularly advantageous to add it before the addition of the aluminate. Inorganic surface treatment agents other than aluminates used for these surface treatments include silicon compounds such as alkali silicate and silicon tetrachloride, titanium compounds such as titanium tetrachloride, zirconium, zinc, magnesium and manganese. Various compounds such as metal compounds and phosphoric acid compounds can be used. Further, as a method of treating the surface of the titanium dioxide particles with a hydrous metal oxide, there is disclosed in JP-A-3-2757.
It can also be carried out by the method described in JP-A-68, JP-A-5-286721 or the like.

The titanium dioxide pigment preferably used in the practice of the present invention has a number average diameter of 0.110 μm to 0.15.
It is 0 μm. Number average diameter is 0.110 μm
The titanium dioxide pigment, which is ˜0.150 μm, can be obtained by producing it under its predetermined production conditions. Production conditions of titanium dioxide pigment, especially firing temperature, firing time, inorganic compounds that are present during firing, such as the type and abundance of inorganic compounds and their combination compounds described or exemplified in JP-B-48-18718 Can be determined by measuring the number average diameter of titanium dioxide pigment produced under a series of combined experimental conditions. At that time, as the firing conditions for increasing the number average diameter, a high firing temperature, a long firing time, and a small amount of an inorganic compound present during firing are typical conditions, while on the other hand, the firing conditions for reducing the number average diameter are As typical conditions, a low baking temperature, a short baking time, and a large amount of an inorganic compound present during baking are present. The firing conditions for the titanium dioxide pigment used in the practice of the present invention include a firing temperature of 800 ° C. to 1100 ° C., a firing time of 15 minutes to 5 hours, and an inorganic compound abundance.
Combination conditions ranging from 0.2% to 5% by weight, based on titanium dioxide, calculated in the form of inorganic oxides, are particularly preferred.

The titanium dioxide pigment preferably used in the practice of the present invention is an organic surface-treated pigment. As the organic surface treatment agent preferably used, γ-chloropropyltrimethoxysilane, vinyltrimethoxysilane,
Methyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, γ
-Methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltris (2-methoxyethoxy)
Silane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxy Silanes, silane coupling agents such as γ-ureidopropyltriethoxysilane, alkylpolysiloxanes, alkylarylpolysiloxanes, alkylhydrogenpolysiloxanes such as dimethylpolysiloxane, dimethylphenylpolysiloxane, organopolysiloxanes such as methylhydrogenpolysiloxane. Siloxane compound, polyether-modified siloxane described in Japanese Patent Publication No. 4-34139, zircoaluminate coupling agent described in Japanese Patent Publication No. 4-76463, triethanolamine, triisopropanolamine, etc. Alkanolamine compound, trimethylol ethane, polyhydric alcohol compounds such as trimethylolpropane, it may be mentioned an amide compound and the like and mixtures thereof described in JP Kokoku 4-76464. The organic surface treatment is preferably performed by adding an organic surface treatment agent to the titanium dioxide slurry at any stage before spray drying the titanium dioxide slurry. Organic surface treatment agents include water, methanol, ethanol,
It may be added after being dissolved / diluted in an appropriate solvent such as acetone, or may be added without being diluted.

The titanium dioxide pigment used in the practice of the present invention is suitably washed with water and finely pulverized as described in Japanese Patent Publication No. 38292/1989, and has a suspension electric conductivity of 55 μmho.
(ΜΩ ^{- 1)} / cm or less, particularly 50μmho (μΩ ^-1) / cm or less are preferred ones, as described in JP Matatoku Sho 63-4489, titanium dioxide pigment under the conditions of 2 hours at 110 ° C. The loss on drying is preferably 0.35% by weight or less.

As a method for incorporating the titanium dioxide pigment used in the practice of the present invention into the surface resin layer for coating the base paper, a so-called masterbatch in which the titanium dioxide pigment is previously incorporated in the thermoplastic resin at a constant concentration is used. It is prepared and used by diluting and mixing it with a thermoplastic resin for dilution to a desired ratio, or by forming a so-called compound in which a titanium dioxide pigment is contained in a thermoplastic resin at a desired composition ratio and used. Although it is suitable, it is preferably contained as a masterbatch. To make these masterbatches and compounds, a Banbury mixer, a kneader, an extruder for kneading, a roll kneader, a kneader disclosed in JP-A-6-110158 and the like are usually used. Further, these various kneading machines may be used in combination of two or more kinds.

The masterbatch of the titanium dioxide pigment preferably used in the practice of the present invention has an oxidation induction period of 3
It is preferably 0 seconds to 900 seconds, and 40 seconds to 600 seconds.
Seconds are more preferable, and those of 50 seconds to 350 seconds are particularly preferable. The term "oxidation induction period" as used herein means that 10 mg of a sample is set in an aluminum pan in a differential scanning calorimeter, nitrogen gas is passed through, and the temperature is rapidly raised after 5 minutes.
Fix at 0 ° C. After 5 minutes, the nitrogen gas was switched to the air gas to start the measurement, and the change in the heat quantity with the lapse of time up to at least the exothermic peak was automatically recorded on a chart. Thus, from the start of measurement (at the time of switching to air gas), the time from the start of measurement to the intersection of the tangent of the heat quantity change curve from the beginning of the exothermic reaction to the tangent of the heat quantity change curve from the beginning of the exothermic reaction to This time is defined as the oxidation induction period (second).

During the preparation of the titanium dioxide pigment masterbatch or compound, it is preferred to carry out the preparation in the presence of an appropriate amount of a suitable lubricant. Specifically, as the lubricant, it is preferable to use a fatty acid metal salt such as zinc stearate, calcium stearate, aluminum stearate, magnesium stearate, zinc palmitate, zinc myristate, calcium palmitate, and particularly zinc stearate or / And magnesium stearate are preferred. In addition, the amount thereof is usefully in the range of 0.1% by weight to 20% by weight with respect to the titanium dioxide pigment.
A range of 1% to 7.5% by weight is preferred.

When preparing the titanium dioxide pigment masterbatch or compound, it is preferable to carry out the preparation in the presence of an appropriate amount of an appropriate antioxidant. In particular,
Hindered phenol-based antioxidants described or exemplified in JP-A-1-105245, phosphorus-based antioxidants described or exemplified in JP-A-55-142335, and various antioxidants such as hindered amines and sulfur-based antioxidants It is preferred that the agent is present in an appropriate amount. The amount of antioxidant present during preparation of a titanium dioxide masterbatch or compound is 50
The range of ppm to 1500 ppm is preferable, but 120 ppm to 9
The range of 50 ppm is more preferable.

Further, as the hindered phenolic antioxidant which is preferably present at the time of preparation of the titanium dioxide pigment masterbatch or compound, for example, 1,3,5-trimethyl-2,4,6-tris (3,3 5
-Di-tert-butyl-4-hydroxybenzyl) benzene, tetrakis [methylene (3,5-di-tert-butyl-4-hydroxy-hydrocinnamate)] methane, octadecyl-3,5-di-tert-butyl -4-hydroxy-hydrocinnamate, 2,2 ', 2 "-tris [(3,
5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] ethyl isocyanurate, 1,3,5-
Tris (4-tert-butyl-3-hydroxy-2,6-
Di-methylbenzyl) isocyanurate, tetrakis (2,4-di-tert-butylphenyl) 4,4'-biphenylene diphosphite, 4,4'-thiobis- (6-
tert-butyl-0-cresol), 2,2'-thiobis-
(6-tert-butyl-4-methylphenol), tris- (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 2,2'-methylene-bis- (4-methyl-6-tert) -Butylphenol), 4,4'-methylene-bis- (2,6-di-tert-butylphenol), 4,
4'-butylidene bis- (3-methyl-6-tert-butylphenol), 2,6-di-tert-butyl-4-methylphenol, 4-hydroxy-methyl-2,6-di-t
ert-butylphenol, 2,6-di-tert-butyl-4
Examples include -n-butylphenol. Further, two or more kinds of antioxidants may be used in combination depending on the characteristics of the antioxidant.

As a method for allowing the antioxidant to be present at the time of preparing the titanium dioxide pigment masterbatch or compound, a so-called compound in which the antioxidant is previously contained in the thermoplastic resin may be used. Alternatively, an appropriate amount of a resin containing an antioxidant in a relatively high concentration may be used, or an antioxidant may be added when a masterbatch or compound is produced by a kneader. Further, the above methods may be appropriately combined depending on the type and content of the antioxidant used.

As a method of coating the resin layer on the base paper surface of the photographic material support in the present invention, the resin layer is cast on the running base paper in a film form from its slit die by using a melt extruder. The coating is preferably performed by a so-called melt extrusion coating method. At that time, the temperature of the molten film is preferably 270 to 330 ° C. In the case of a polyester resin layer, 220 to
It is preferably 300 ° C. The slit die is preferably a flat die such as a T die, an L die, and a fishtail die, and the slit opening diameter is 0.1 to 2 mm.
It is desirable that Further, it is preferable that the base paper is subjected to an activation treatment such as a corona discharge treatment or a flame treatment before the base paper is coated with the resin layer. Further, as described in JP-B-61-42254, a resin layer may be coated on the running base paper after the ozone-containing gas is blown onto the surface of the molten resin which is in contact with the base paper. Further, the front and back resin layers are sequentially and preferably continuously extrusion-coated, preferably the base paper is coated by a so-called tandem extrusion coating method, and the front and back resin layers are, if necessary, The coating is preferably performed by a multi-layer extrusion coating method, which has a multi-layer structure of two or more layers. In addition, the resin layer surface is a glossy surface,
It can be processed into a finely rough surface, a matte surface, a silk surface, etc. described in JP-1973-2. In particular, the effect of the present invention is remarkable in the support for photographic material in which the surface resin layer has a glossy surface or a slightly rough surface.

The coating thickness of the surface resin layer of the support for photographic materials in the present invention is usefully in the range of 8 to 100 μm, preferably 12 to 60 μm, and 18 to 40.
The range of μm is particularly preferred. The base paper surface on the back side is coated with a back resin layer containing a resin capable of forming a film as a main component, and the resin is particularly preferably a polyethylene-based resin, and the coating thickness of the back side resin layer is particularly preferably. It is preferable to appropriately set the curl balance, and a range of 8 to 100 μm is generally useful, but preferably 1
It is in the range of 2 to 60 μm.

In the front resin layer of the support for photographic materials in the present invention and, if necessary, in the back resin layer, various additives other than the above-mentioned titanium dioxide pigment, fatty acid metal salt and antioxidant are contained. It can be done. In addition to titanium dioxide pigments, white pigments such as zinc oxide, talc, and calcium carbonate, fatty acid amides such as stearic acid amide and arachidic acid amide, release agents such as cobalt blue, ultramarine blue, cerian blue, and phthalocyanine blue Pigments and dyes, cobalt violet, fast violet, magenta pigments and dyes such as manganese violet, described in Japanese Examined Patent Publication No. 4-2175 or quinacridone reddish pigment, or described or exemplified in JP-A-2-254440. Various additives such as the fluorescent whitening agent and the ultraviolet absorber can be appropriately combined and contained. These additives are preferably contained together in the titanium dioxide pigment masterbatch or compound used in the practice of the present invention, or as a separate resin masterbatch or compound.

The base paper used in the practice of the present invention is preferably natural pulp paper containing normal natural pulp as a main component. Further, a mixed paper made of synthetic pulp and synthetic fiber containing natural pulp as a main component may be used. Such natural pulp is described or exemplified in JP-A-58-37642, JP-A-60-67940, JP-A-60-69649, JP-A-61-35442 and the like. It is advantageous to use such appropriately selected natural pulp. Natural pulp was subjected to usual bleaching treatment such as chlorine, hypochlorite, chlorine dioxide bleaching, alkali extraction or alkali treatment and, if necessary, oxidative bleaching treatment with hydrogen peroxide, oxygen, etc., and a combination thereof. Softwood pulp, hardwood pulp,
Wood pulp, which is a mixed pulp of softwood and hardwood, is advantageously used, and various kinds of kraft pulp, sulfite pulp, soda pulp and the like can be used.

The base paper containing natural pulp as a main component, which is preferably used in the practice of the present invention, may contain various additives when preparing a stock slurry. As a sizing agent, a fatty acid metal salt, a fatty acid or a combination thereof, an alkylketene dimer emulsion described or exemplified in JP-B-62-7534, an epoxidized higher fatty acid amide or a combination thereof, an alkenyl or alkylsuccinic anhydride emulsion Products, rosin derivatives, etc.
Anionic, cationic or amphoteric polyacrylamide, polyvinyl alcohol, cationized starch, vegetable galactomannan, etc. as a wet paper strength enhancer, polyamine polyamide epichlorohydrin resin, etc., as a filler,
Clay, kaolin, calcium carbonate, titanium oxide, etc. as a fixing agent, water-soluble aluminum salts such as aluminum chloride and vanadium sulfate, etc., as a pH adjusting agent, caustic soda, sodium carbonate, sulfuric acid, etc. JP-A-63-204251 Publication, color pigment described or exemplified in JP-A 1-266537, etc.,
It is advantageous to incorporate a coloring dye, a fluorescent whitening agent and the like in an appropriate combination.

Further, in or on the base paper mainly composed of natural pulp which is preferably used in the practice of the present invention,
A composition comprising various water-soluble polymers or hydrophilic colloids or latexes, antistatic agents, and additives may be contained or applied by size press or tab size press or coating such as blade coating or air knife coating. it can. As a water-soluble polymer or hydrophilic colloid, as described in JP-A 1-266537 or exemplified starch-based polymer, polyvinyl alcohol-based polymer, gelatin-based polymer, polyacrylamide-based polymer, cellulose-based polymer, emulsion, latex, Petroleum resin emulsion, JP-A-55-4
No. 027, an emulsion or latex of a copolymer having ethylene and acrylic acid (or methacrylic acid) described or exemplified in JP-A 1-180538 at least as a constituent, styrene-butadiene-based, styrene-acrylic-based, Vinyl acetate-acrylic, ethylene-vinyl acetate-based, butadiene-methyl methacrylate-based copolymers and emulsions or latexes of carboxy-modified copolymers thereof, as antistatic agents, alkali metal salts such as sodium chloride and potassium chloride, Clay, pigments such as alkaline earth metal salts such as calcium chloride and barium chloride, colloidal metal oxides such as colloidal silica, organic antistatic agents such as polystyrene sulfonate, etc.
Kaolin, calcium carbonate, talc, barium sulfate, titanium oxide, etc., as a pH adjuster, hydrochloric acid, phosphoric acid, citric acid, caustic soda, etc., as well as the above-mentioned color pigments, coloring dyes, optical brighteners and other additives are appropriately combined. It is advantageous to include them.

The thickness of the base paper used for carrying out the present invention is not particularly limited, but the basis weight is 20 to 250 g /
Those of m ² are preferred.

The base paper used in the practice of the present invention has a thickness unevenness index Rpy in the paper making direction defined below.
Is preferably 250 mV or less, more preferably 200 mV or less, most preferably 150 mV or less.
The film thickness unevenness index Rpy referred to here is an electronic micrometer using a film thickness measuring instrument that runs a sample between two spherical stylus and measures the thickness variation of the sample as an electric signal through an electronic micrometer. Sensitivity range is ± 1
The thickness variation in the papermaking direction of the sample was measured by scanning at a constant speed of 1.5 m / min in the papermaking direction of the sample after adjusting the zero point under the condition of 5 μm / ± 3V, and the obtained measurement signal value was used as the FFT. Using an analyzer, use a Hanning window for the time window to perform a fast Fourier transform, and obtain a power spectrum (unit: mV ² ) based on the arithmetic mean of 128 integrations.
A value (unit: mV) obtained by summing power values in a frequency range of 25 Hz, multiplying by 2/3, and multiplying the resulting value by 1/2.
It is.

As a method for producing a base paper having a thickness unevenness index Rpy of 250 mV or less, which is preferably used in the practice of the present invention, specifically, 30% by weight or more of hardwood pulp which is short fiber and easy to smooth, It is preferably used in an amount of 50% by weight or more and beaten by a beater so that the long fiber content is reduced as much as possible. For example, the beating of the pulp is preferably such that the weighted average fiber length of the pulp after beating is 0.4 to 0.75 mm. Next, a base paper is preferably made by a Fourdrinier paper machine by adopting a suitable paper making method for a paper stock slurry to which internal additives are added so that a uniform formation is obtained.
Specifically, for example, to give a suitable turbulence to the stock slurry, using a Fourdrinier paper machine having a suitable upper dewatering mechanism as described or exemplified in JP-A-61-284762, wet part As a press, a multi-stage wet press, preferably a wet press with three or more stages, and a smoothing crawl at the final stage of the press part are combined so that a uniform texture can be obtained by combining appropriate papermaking methods. Papermaking, then machine calender after papermaking,
It is possible to produce a base paper having a thickness unevenness index Rpy of 250 mV or less by carrying out a calendar treatment using a super calender, a thermal calender, or the like.

As the base paper mainly composed of natural pulp used in the practice of the present invention, a stylus type three-dimensional surface roughness meter on the front side of the base paper is used from the viewpoint of further improving the glossiness of the photographic material. Center surface average roughness SRa in the papermaking direction at a cutoff value of 0.8 mm (hereinafter, cutoff value measured using a stylus type three-dimensional surface roughness meter on the front side of the base paper is 0.8 mm).
The term "center surface average roughness SRa in the paper making direction" in the above may be simply abbreviated as center surface average roughness SRa) is 1.45μ.
m or less is useful, preferably 1.40 μm or less, more preferably 1.35 μm or less, 1.
It is particularly preferably 25 μm or less. The center plane average roughness SRa at a cutoff value of 0.8 mm measured by using the stylus type three-dimensional surface roughness meter referred to in the present specification is defined by Formula 1.

[0066]

[Equation 1]

In Expression 1, Wx represents the length of the sample surface area in the X-axis direction (papermaking direction), Wy represents the length of the sample surface area in the Y-axis direction (direction perpendicular to the papermaking direction), and Sa Represents the area of the sample area.

As a method for producing a base paper having a center surface average roughness SRa of 1.45 μm or less, which is preferably used in the practice of the present invention, specifically, a sulfite pulp which is likely to have smoothness, preferably a hardwood Sulfite pulp is used in an amount of 30% by weight or more, preferably 50% by weight or more, and multi-stage pressure pressing is performed during the drying of the wet paper. Further, after the base paper is made, at least using a machine calender, a super calender, a thermal calender, etc. Calendar processing of two or more series,
For example, the base paper is subjected to a machine calendering treatment and / or a thermal machine calendering treatment as the first series of calendering treatments, and then a machine calendering treatment as necessary for the second series and subsequent calendering treatments.
By performing the thermal soft calender treatment described or exemplified in 110939, it is possible to manufacture a base paper having a center surface average roughness SRa of 1.45 μm or less. Further, various water-soluble polymers or hydrophilic colloids or polymer latexes in or on the base paper are applied as a solid coating amount of 1.0 g / by a size press, a tab size press, a blade coating, an air knife coating or the like. m ²
Above all, it is preferable to contain or coat 2.2 g / m ² or more.

The surface of the support of the photographic material of the present invention is subjected to activation treatment such as corona discharge treatment and flame treatment, and then, it is carried out in JP-A-61-84643 and JP-A-1-92740.
An undercoat layer as described or exemplified in Japanese Patent Application Laid-Open No. Hei. Further, on the back resin layer surface of the support for photographic materials in the present invention, various back coat layers are coated on the back resin layer surface for antistatic etc. after subjecting to activation treatment such as corona discharge treatment and flame treatment. You can Further, the back coat layer has a Japanese Patent Publication No. 52-18020, Japanese Patent Publication No. 57-9059, Japanese Patent Publication No. 57-53940, Japanese Patent Publication No. 58-56859, and Japanese Patent Laid-Open No.
9-214849, JP-A-58-184144 and the like or exemplified inorganic antistatic agents, organic antistatic agents, hydrophilic binders, latexes, curing agents, pigments, surfactants and the like in appropriate combination It can be done.

The support for photographic materials in the present invention is coated with various photographic image forming layers and is for color photographic printing paper, black-and-white photographic printing paper, typesetting photographic paper, copy photographic paper, reversal photographic material. , Silver salt diffusion transfer method, negative and positive, and printing materials. For example, silver chloride, silver bromide, silver chlorobromide, silver iodobromide, and silver chloroiodobromide emulsion layers can be provided. The silver halide photographic emulsion layer can contain a color coupler to provide a multilayer silver halide color photographic image forming layer. Further, a photographic image forming layer for silver salt diffusion transfer method can be provided. As the binder for the photographic image forming layer, hydrophilic polymer substances such as polyvinylpyrrolidone, polyvinyl alcohol, and sulfate compounds of polysaccharides can be used in addition to ordinary gelatin. Further, the photographic image forming layer may contain various additives. For example, as sensitizing dyes, cyanine dyes, merocyanine dyes, etc., as chemical sensitizers, water-soluble gold compounds, sulfur compounds, etc.
As antifoggants or stabilizers, hydroxy-triazolopyrimidine compounds, mercapto-heterocyclic compounds, etc., as hardeners formalin, vinyl sulfone compounds, aziridine compounds, etc., coating aids, alkylbenzene sulfonates, sulfosuccinate salts As anti-staining agents, dialkyl hydroquinone compounds, etc., as well as optical brighteners, sharpness-improving dyes, antistatic agents, pH adjusters, foggants, and water-soluble iridium and water-soluble agents during the production and dispersion of silver halide. A suitable rhodium compound or the like can be contained in an appropriate combination.

The photographic material according to the present invention is exposed, developed and stopped as described in "Photosensitive Material and Handling Method" (Kyoritsu Shuppan, Goro Miyamoto, Photographic Technology Course 2) according to the photographic material. , Fixing, bleaching, stabilizing, etc. can be performed. Further, the multi-layer silver halide color photographic material may be treated with a developer containing a development accelerator such as benzyl alcohol, thallium salt, phenidone or the like, or may be treated with a developer substantially free of benzyl alcohol. it can.

[0072]

EXAMPLES Next, examples will be described to more specifically describe the present invention.

Examples 1 to 9 and Comparative Examples 1 to 3 During the production of anatase type titanium dioxide by the sulfuric acid method, a hydroxide prepared by neutralizing the titanyl sulfate solution was added as a seed to the titanyl sulfate solution. After that, the temperature was raised and the mixture was boiled and hydrolyzed to produce titanium dioxide.
Then, it was filtered and washed, and the anatase-type titanium dioxide clinker produced under the firing conditions predetermined so as to have the particle size shown in Table 1 was dry-pulverized with a centrifugal roller mill, and the pulverized product was added in the presence of sodium hydroxide. Suspended in water to form titanium dioxide slurry, wet-milled in a wet ball mill, wet-classified by using a continuous horizontal centrifuge, about 25% by weight substantially free of coarse-grained titanium dioxide
50% by weight of the titanium dioxide slurry of 0.15%, 0.50% or 2.0% by weight calculated on the dry basis of titanium dioxide in the form of Al ₂ O _3. Was added for 30 minutes. The pH of the slurry was then lowered to 7.0 by addition of 20% by weight sulfuric acid and the slurry was aged for 2 hours. After aging, the first mother liquor of the titanium dioxide slurry surface-treated with hydrous aluminum hydroxide was filtered with a filter press, and then the titanium dioxide cake in the filter press was washed with running water to a suspension of 50 μmho (μΩ ⁻¹ ) / cm. It was washed under predetermined washing conditions until a titanium dioxide pigment having electric conductivity was obtained.

Then, the titanium dioxide cake was taken out, water was added, and the titanium dioxide concentration was adjusted to 5 with an industrial mixer.
Prepared to be an aqueous slurry of 00 g / l, and subsequently, with a hot air inlet temperature of about 150 ° C., a spray dryer (manufactured by EYELA, SD
-1 type) and spray-dried, and further, using a steam mill equipped with a quantitative feeder, pulverized through superheated steam at about 250 ° C. to produce a titanium dioxide pigment used in the present invention.

Separately, the above titanium dioxide cake was dried in a rotary drying furnace, and subsequently pulverized through superheated steam at about 250 ° C. using a steam mill equipped with a constant quantity feeder to obtain titanium dioxide pigments for comparison having different drying systems. Manufactured.

For each of the titanium dioxide pigments thus obtained, a low density polyethylene resin (density:
923 g / cm ³ , MFR = 8.5 g / 10 minutes) 47.5% by weight,
Titanium dioxide pigment 50% by weight and zinc stearate 2.5% by weight, as an antioxidant, 240 ppm of 1,
3,5-tris (4-tert-butyl-3-hydroxy-
In the presence of 2,6-dimethyl-benzyl) cyanurate, a master batch of titanium dioxide pigment, which was produced by thoroughly kneading at 150 ° C. using a Banbury mixer, cooling and pelletizing, was obtained.

On the other hand, the fiber length of the pulp after beating a mixed pulp composed of 30% by weight of hardwood bleached kraft pulp and 70% by weight of hardwood bleached sulfite pulp (JAPAN)
100 weight of pulp after beating so that the length-weighted average fiber length measured according to TAPPI paper pulp test method No. 52-89 "Paper and pulp fiber length test method" is 0.58 mm. 3 parts by weight of cationized starch, 0.2 part by weight of anionized polyacrylamide, 0.4 part by weight of an emulsion of alkyl ketene dimer (as ketene dimer content), 0.4 part by weight of polyamide epichlorohydrin resin and an appropriate amount. A fluorescent substance brightening agent, a blue dye, and a red dye were added to prepare a stock slurry. After that, the stock slurry is placed on a Fourdrinier paper machine running at 200 m / min to form a web while giving an appropriate turbulence, and the linear pressure in the wet part is in the range of 15 kg / cm to 100 kg / cm. Adjusted 3 steps wet press, smoothing roll treatment, 30kg / cm in subsequent drying part
After performing a two-stage pressure press in which the linear pressure was adjusted in the range of ˜70 kg / cm, it was dried. Then, in the middle of drying, 25 g / size-pressing liquid consisting of 4 parts by weight of carboxy-modified polyvinyl alcohol, 0.05 part by weight of optical brightening agent, 0.002 part by weight of blue dye, 4 parts by weight of sodium chloride and 92 parts by weight of water. m ² size was pressed, the finally obtained base paper moisture is dried to be 8 wt% in absolute dry moisture, linear pressure 70kg
machine calendered at 170 g / m ² to obtain a film thickness unevenness index Rpy of 130 mV and a center surface average roughness SR
A base paper having an a of 1.20 μm was produced.

Next, the base paper surface (rear surface) opposite to the side on which the photographic image forming layer is provided is subjected to corona discharge treatment, and then the low density polyethylene resin (density 0.924 g / cm ³ , MFR, MFR
= 1 g / 10 minutes) 30 parts by weight and a high-density polyethylene resin (density 0.967 g / cm ³ , MFR = 15 g / 10 minutes) 70 parts by weight of a compound resin composition at a resin temperature of 320 ° C. for 25 hours.
A resin thickness of μm was melt extrusion coated at a running speed of the base paper of 200 m / min. At this time, as a cooling roll,
The center line average roughness Ra of the back resin layer surface defined by JIS K 0601 was 1.0 μm, and the roughness was used. The cooling roll used was a cooling roll surface-roughened by a liquid honing method, and was operated at a cooling water temperature of 12 ° C.

Subsequently, the base paper surface (surface) on which the photographic image forming layer is provided is subjected to corona discharge treatment, and then 30 parts by weight of the titanium dioxide pigment master batch described above and a high density polyethylene resin (density 0.967 g / cm ³ , MFR =
6.8 g / 10 min) and 20 parts by weight of low-density polyethylene resin (density 0.924 g / cm ³ , MFR = 3.0 g / 10 min), and a resin composition of 3 parts at a resin temperature of 315 ° C.
Melt extrusion coating was performed at a thickness of 0 μm at a running speed of the base paper of 200 m / min and an effective press pressure of 30 kg / cm ² of a cooling roll and a press roll using a melt extrusion coating machine.
At this time, as the cooling roll, a chrome-plated, slightly rough surface was used, and the cooling water was operated at a temperature of 12 ° C. Further, the melt extrusion coating of the front and back resin compositions was performed by a so-called tandem system in which extrusion coating was sequentially performed.

Subsequently, after processing the front and back resins and before winding up, the resin layer surface on the back side of the resin-coated paper was subjected to corona discharge treatment, and then the following backcoat coating liquid was applied on-machine.
It consists of gelatin: silicon dioxide matting agent (average particle size 2 μm) = 3: 1 as dry weight, and contains an appropriate amount of a coating aid and an inorganic antistatic agent in addition to an epoxy hardener with 15% by weight of gelatin. Backcoat coating liquid is gelatin content 2
A support for photographic material was obtained by coating with a coating amount of g / m ² minutes.

As a method for evaluating the releasability of the surface resin layer from the cooling roll at the time of producing each photographic material support,
The peeling angle θ shown in FIG. 1 was measured, and the grade irregularity of the entire peeling was considered to perform grade evaluation on a 10-point scale.
Grades 10 to 10 are used as evaluation criteria (the larger the grade value, the better the peelability, and the smaller the grade value, the worse the peelability and the irregular peeling state).
9: Peeling angle θ is less than 3 °, extremely good peeling property, Grades 8 to 7; Peeling angle θ is less than 5 °, good peeling property, Grades 5 to 6; Peeling angle θ is less than 8 °, peeling property It shows slight irregularity, but there is no problem in practical use, grade 4 to
1 indicates that the peeling angle θ is 8 ° or more and the peeling irregularity is exhibited and the peelability is a problem in actual operation.

Further, a black and white silver halide photographic image forming layer is coated as an image forming layer on the photographic material support to produce a photographic material, and the sharpness and storability of the printed image of the photographic material are described below. Evaluation was carried out by the described method.

Corona discharge treatment was applied to the resin surface on the front side of the support until the resin-coated paper was wound up after application of the back coat coating solution, and 0.75 g of lime-treated gelatin and low molecular weight gelatin (Nitta Gelatin Co., Ltd. P-3226)
0.75 g, 0.3 g of a 10 wt% methanol solution of butyl paraoxybenzoate, and 0.45 g of a 5 wt% mixture of methanol and water of sulfosuccinic acid-2-ethylhexyl ester salt were prepared, and the total amount was adjusted to 100 g with water. The subbing coating solution was uniformly applied on-machine so that the coating amount of gelatin was 0.06 g / m ² to obtain a support for photographic materials.

Next, a black-and-white photographic printing paper was obtained by providing an emulsion layer and its protective layer as a black-and-white silver halide photographic image forming layer on the undercoat layer on the front side of the support for photographic materials. Emulsion layer is potassium hexachlororhodium (III) 2.4 × 10 ^-6 g
ArBr / produced by generating and dispersing 19.2 g of silver halide grains with silver nitrate in 8.6 g of gelatin in the presence of
AgCl / AgI = 50.6 / 49.0 / 0.4 (mol%) with halogen composition having an average particle size of 0.6μ and optimum sensitivity of sulfur sensitization consisting essentially of [1,0,0] face Including neutral silver halide photographic emulsion, and in addition to gelatin necessary for film formation, an appropriate amount of stabilizer, sensitizing dye, coating aid, hardener, optical brightener, thickener, etc. 2.3g / with silver nitrate
m ² and gelatin were applied in multiple layers together with a protective layer at a coating amount corresponding to 4.5 g / m ² . The protective layer contains a coating aid and a hardener in addition to gelatin equivalent to ² g / m ² .

Regarding the evaluation of the sharpness of the printed image,
After the coated and dried sample is stored at 35 ° C and normal humidity for 1 day,
The resolution chart was brought into close contact with the sample, exposed with white light, and subjected to black and white development to obtain a test sheet. This test sheet is measured with a microdensitometer and calculated with a personal computer according to a conventional method to obtain the image sharpness MT.
F (Modulation Transfer Function) was determined, and the sharpness of the printed image of the support for photographic material was determined. The larger the value of MTF, the higher the sharpness of the printed image.

Regarding the evaluation of the storability of the photographic material, the coated and dried sample was 35 ° C., 1 day under normal humidity and 55 ° C.
After storage for 4 days at sensitometry, the product was exposed for sensitometry, stopped after black and white development, fixed, washed with water and dried to measure the photographic characteristics, and the storability was evaluated.

The evaluation criteria for the storability of photographic materials are as follows:
5: Sensitivity change and fogging were considerably small, and storage stability was excellent. 4: Sensitivity change and fog generation were small, and storage stability was good. 3: Sensitivity change and fogging occurred a little, but to a practical extent to some extent 2: Sensitivity change and fogging occurred, storage quality was sometimes a problem, 1: Sensitivity change and fogging occurred considerably, It represents the degree to which the storability cannot be put to practical use.

The results obtained are shown in Table 1.

[0089]

[Table 1]

Note that (Note 1) to (Note 4) in Table 1 are as follows.

(Note 1) Calculated in the form of Al ₂ O ₃ and represents weight% based on titanium dioxide.

(Note 2) It is indicated by the number average diameter described in the text of the specification.

(Note 3) Spray method: represents a method of spray drying. Rotational drying method: A method of drying in a tumble drying furnace.

(Note 4) MTF is shown as a value at 7 lines / mm.

As is clear from Table 1, the titanium dioxide pigment contained in the surface resin layer of the resin-coated support for paper-type photographic material was produced by spray drying and had an apparent density of 0.1. The support for photographic materials (Examples 1 to 9) in the present invention using the titanium dioxide pigment of 32 g / cm ³ or more has a high sharpness of a printed image and has good storability of photographic materials, and It can be clearly seen that it is an excellent support in which the releasability of the surface resin layer from the cooling roll is also good. Also, as the titanium dioxide pigment,
From the viewpoint of improving the sharpness of the printed image, the storability of the photographic material, and the releasability of the surface resin layer from the cooling roll, the apparent density is preferably 0.35 g / cm ³ or more, and the effect of the present invention is obtained. In particular, from the viewpoint of the effect of improving the sharpness of the printed image, the number average diameter is preferably in the range of 0.110 μm to 0.150 μm, and more preferably in the range of 0.115 μm to 0.135 μm. . Further, as the titanium dioxide pigment, from the viewpoint of the effect of the present invention, the surface thereof contains at least aluminum atoms in an amount of 0.25% to 1.5% by weight calculated as anhydrous metal oxide per titanium dioxide. It can be seen that the one treated with the hydrous metal oxide is preferable.

On the other hand, as the titanium dioxide pigment, a pigment dried by a rotary drying method was used (Comparative Example 2) or an apparent density of less than 0.32 g / cm ³ was used (Comparative Examples 1 and 2). The support for photographic materials other than the present invention of Comparative Example 3) has a problem that the sharpness of the printed image is low, the storage stability is poor, and the releasability of the surface resin layer from the cooling roll is poor. .

Examples 10 to 20 and Comparative Example 4 In Examples 1 to 9, Comparative Example 1 and Comparative Example 3, a 2% by weight aqueous solution of methyltrimethoxysilane per titanium dioxide was added to the aqueous slurry before spray drying. A titanium dioxide pigment was produced in the same manner as in Examples 1 to 9 and Comparative Examples 1 and 3 except that 1.0% by weight (as an organic substance content) was added, and the mixture was thoroughly mixed with stirring and then spray-dried. Further, in Comparative Example 2, Comparative Example 2 except that a 2 wt% aqueous solution of methyltrimethoxysilane was added to the aqueous slurry before filtering with a filter press in an amount of 1.0 wt% per titanium dioxide (as an organic substance content). A titanium dioxide pigment was produced in the same manner as in. The same procedure as in Example 1 was carried out except that these titanium dioxide pigments were used instead of the titanium dioxide pigment used in Example 1.

The results obtained are shown in Table 2.

[0099]

[Table 2]

Note that (Note 1) to (Note 4) in Table 2 have the same meanings as those in Table 1.

As is clear from Table 2, the titanium dioxide pigment contained in the surface resin layer of the resin-coated support for paper-type photographic material was produced by organic surface treatment and spray drying. , And the apparent density is 0.
The support for photographic materials of the present invention (Examples 10 to 26) using the titanium dioxide pigment of 32 g / cm ³ or more has a high sharpness of a printed image, and has good storability of photographic materials, and It can be clearly seen that it is an excellent support in which the releasability of the surface resin layer from the cooling roll is also good.
The titanium dioxide pigment has an apparent density of 0.35 g / cm ^{3 in} terms of the effect of improving the sharpness of the printed image, the storability of the photographic material, and the releasability of the surface resin layer from the cooling roll.
It is well understood that the above are preferable, and those having an apparent density of 0.38 g / cm ³ or more are particularly preferable. Further, from the viewpoint of the effect of the present invention, particularly the effect of improving the sharpness of the printed image, the number average diameter is preferably in the range of 0.110 μm to 0.150 μm, and in the range of 0.115 μm to 0.135 μm. It can be clearly seen that the ones are more preferable. Further, as a titanium dioxide pigment, from the viewpoint of the effect of the present invention, the surface thereof contains at least aluminum atoms in an amount of 0.25% to 1.5% by weight calculated as anhydrous metal oxide per titanium dioxide. It can be seen that those treated with the hydrous metal oxide are preferable. Further, from the comparison between Table 1 and Table 2, it is well understood that the titanium dioxide pigment used in the present invention is preferably the one having an organic surface treatment.

On the other hand, a support for photographic materials other than the present invention when a titanium dioxide pigment having an apparent density of less than 0.32 g / cm ³ dried by a rotary drying method was used (Comparative Example 4) was used. , The sharpness of the printed image is low, the storage stability is poor,
Furthermore, the peelability of the surface resin layer from the cooling roll is poor, and it is understood that there is a problem.

Examples 21 to 27 and Comparative Examples 5 to 8 At the time of producing anatase type titanium dioxide by the sulfuric acid method, a titanyl sulfate aqueous solution was added to warm water to seed (internal seed).
Was generated, and the temperature was raised and boiled to perform hydrolysis to produce titanium dioxide. After that, described in Example 5 except that the firing conditions preliminarily determined so that the particle size of titanium dioxide shown in Table 3 was obtained and the surface treatment with the amount of hydrous aluminum oxide shown in Table 3 was performed. The titanium dioxide pigment of the inner seed method was manufactured through a procedure similar to that of the outer seed method. Also, use firing conditions that are predetermined so that the particle size of titanium dioxide shown in Table 3 is obtained, and Table 3
An external seed method titanium dioxide pigment was produced in the same manner as in Example 5, except that the surface treatment was performed with the amount of hydrous aluminum hydroxide described in. For comparison, a rotary-drying titanium dioxide pigment was produced in the same manner as in Comparative Example 2. Further, a titanium dioxide pigment having an organic surface treatment was produced by performing an organic surface treatment with 1.0% by weight of methyltrimethoxysilane per titanium dioxide in the same manner as in Example 16. These titanium dioxide pigments were used in Example 5
Example 5 was carried out in the same manner as in Example 5 except that the titanium dioxide pigment used in 1 was used instead of the pigment.

The results obtained are shown in Table 3.

[0105]

[Table 3]

Note that (Note 1) to (Note 4) in Table 3 have the same meanings as those in Table 1.

As is clear from Table 3, the titanium dioxide pigment contained in the surface resin layer of the resin-coated support for paper-type photographic material was produced by spray drying and had an apparent density of 0.1. The support for photographic materials of the present invention (Examples 21 to 27) using a titanium dioxide pigment having a content of 32 g / cm ³ or more has a high sharpness of a printed image and a good storability of the photographic material, and It can be clearly seen that it is an excellent support in which the releasability of the surface resin layer from the cooling roll is also good. Further, as the titanium dioxide pigment, one having an apparent density of 0.35 g / cm ³ or more is used in terms of the effect of improving the sharpness of the printed image, the storability of the photographic material, and the releasability of the surface resin layer from the cooling roll. It is well understood that those having an apparent density of 0.38 g / cm ³ or more are particularly preferable. Further, as the titanium dioxide pigment used in the present invention, it is well understood that the external seed method is more preferable from the viewpoint of the overall improvement effect of the present invention. Further, as a titanium dioxide pigment, from the viewpoint of the effect of the present invention, the surface thereof contains at least aluminum atoms in an amount of 0.25% to 1.5% by weight calculated as anhydrous metal oxide per titanium dioxide. It can be seen that those treated with the hydrous metal oxide are preferable. Further, it can be clearly seen that the titanium dioxide pigment used in the present invention is preferably one having an organic surface treatment.

On the other hand, as the titanium dioxide pigment, a pigment dried by a rotary drying method was used (Comparative Example 8) or an apparent density of less than 0.32 g / cm ³ was used (Comparative Examples 5 to 5). It can be seen that the support for photographic materials other than the present invention of 7) has a problem that the sharpness of the printed image is low, the storage stability is poor, and the releasability of the surface resin layer from the cooling roll is poor.

Examples 28 to 38 and Comparative Examples 9 to 10 In Example 1, the titanium dioxide pigment was calculated in the form of Al ₂ O ₃ with respect to titanium dioxide on a dry basis to obtain the weight% shown in Table 4. 50% by weight of sodium aluminate
A titanium dioxide pigment surface-treated with hydrous aluminum oxide prepared in the same manner as in Example 1 except that an aqueous solution was added, or SiO 2 with respect to titanium dioxide on a dry basis.
After addition of 10 wt% aqueous solution of an amount of sodium silicate to a weight% according to calculations in _two forms in Table 4, Table 4 with respect to titanium dioxide dry basis, calculated in the form of Al ₂ O ₃ In the same manner as in Example 1 except that a 50% by weight aqueous solution of sodium aluminate as described in 1. Before raising the pH of the pigment or titanium dioxide slurry with sodium hydroxide, it was calculated in the form of TiO ₂ against titanium dioxide on a dry basis.
5% by weight aqueous solution of titanyl sulfate as described in Table 1 and 50% by weight aqueous solution of sodium aluminate as shown in Table 4 with respect to titanium dioxide on a dry basis. Example 1 was repeated except that the masterbatch of titanium dioxide pigment surface-treated with aluminum oxide hydroxide and titanium oxide was produced in the same manner as in Example 1. The number average diameter of titanium dioxide was in the range of 0.122 μm to 0.127 μm.

The results obtained are shown in Table 4.

[0111]

[Table 4]

Note that (Note 4) to (Note 5) in Table 4 are as follows.

(Note 4) It has the same meaning as that in Table 1.

(Note 5) The treatment amount of the surface treating agent in which the surface of titanium dioxide was surface-treated with hydrous aluminum hydroxide, hydrous silicon dioxide and / or hydrous titanium dioxide was changed to Al ₂ O _{3 with} respect to titanium dioxide on a dry basis. , SiO ₂ ,
It is expressed in% by weight when calculated in the form of TiO ₂ .

As is clear from Table 4, the titanium dioxide pigment contained in the surface resin layer of the support for resin-coated paper-type photographic material was produced by spray drying and had an apparent density of 0. The support for photographic materials of the present invention (Examples 28 to 38) using a titanium dioxide pigment of 32 g / cm ³ or more has a high sharpness of a printed image and good storability of photographic materials, and It can be clearly seen that it is an excellent support in which the releasability of the surface resin layer from the cooling roll is also good. Further, as the titanium dioxide pigment, one having an apparent density of 0.35 g / cm ³ or more is used in terms of the effect of improving the sharpness of the printed image, the storability of the photographic material, and the releasability of the surface resin layer from the cooling roll. It is clear that it is preferable. Further, as the titanium dioxide pigment, in view of the effect of the present invention, the surface thereof is calculated in the form of anhydrous metal oxide per titanium dioxide, and preferably 0.25% by weight to 1.
It can be seen that it has been treated with 5% by weight, particularly preferably from 0.35% by weight to 1.25% by weight, of a hydrous metal oxide containing at least aluminum atoms.

On the other hand, when a titanium dioxide pigment having an apparent density of less than 0.32 g / cm ³ was used (Comparative Example 9-
It can be seen that the support for photographic materials other than the present invention of 10) has a problem that the sharpness of the printed image is low, the storage stability is poor, and the releasability of the surface resin layer from the cooling roll is poor.

Examples 39 to 42 and Comparative Examples 11 to 12 In Examples 24 to 27 and Comparative Examples 7 to 8, instead of the black and white silver halide photographic image forming layers, the following multilayer silver halide color photographic image forming layers were used. Was carried out in the same manner as in Examples 24 to 27 and Comparative Examples 7 to 8 except that the color development processing such as color development, bleach-fixing and water washing processing was performed after decomposition exposure instead of the black and white development processing.

The multilayer silver halide color photographic image forming layer comprises a blue-sensitive silver halide emulsion layer, an intermediate layer, a green-sensitive silver halide emulsion layer and an ultraviolet absorber, which are adjacent to the undercoating layer of the support for image materials. Six layers were simultaneously coated from a multilayer coating E-bar so that the layers, the red-sensitive silver halide emulsion layer and the protective layer were located.

The blue-sensitive silver halide photographic emulsion layer was produced by first heat-forming in the presence of an appropriate amount of potassium hexachloroiridium (III), and had an average grain size of 0, which had a halogen composition of AgBr / AgCl = 95/5. A neutral silver halide emulsion comprising a mixed crystal of [1, 0, 0] and [1, 1, 1] planes, which was sulfur-sensitized to an optimum sensitivity of 0.8 μm, was added in an amount of silver nitrate of 0.8.
In addition to 6 g / m ^{2 of} gelatin, 1.5 g / m ^{2 of} gelatin and a yellow color-forming coupler, an appropriate amount of a stabilizer, a sensitizing dye for blue sensation, a coating aid, a hardener and a thickener. The middle layer is gelatin 1.
In addition to 5g / m ² , a proper amount of color mixture inhibitor, coating aid, thickener,
Including hardeners.

The green-sensitive silver halide emulsion layer comprises a halogen of AgBr / AgCl = 95/5, which is produced by the first thermal formation in the presence of appropriate amounts of potassium hexachlororhodium (III) and potassium hexachloroiridium (III). An acid-processed silver halide emulsion essentially composed of [1,0,0] faces, which has a composition and an average grain size of 0.4 μm and is sulfur-sensitized to an optimum sensitivity, contains 0.6 g / m ² of silver nitrate, and further comprises gelatin. 1.
5 g / m ² and a magenta color coupler, an appropriate amount of stabilizer,
Green sensitizing dye, sharpness improving dye, coating aid, hardener,
Including thickeners. The ultraviolet absorbing layer contains 1.5 g / m ² of gelatin and an appropriate amount of an ultraviolet absorbent, a coating aid, a thickener, a hardener and the like.

The red-sensitive silver halide emulsion layer contains a silver halide emulsion prepared in exactly the same manner as the green-sensitive silver halide emulsion in an amount of silver nitrate of 0.6 g / m ² , and further contains gelatin of 1.5 g / m ^2. In addition to the cyan color coupler, a proper amount of a stabilizer, a red sensitizing dye, a sharpness improving dye, a coating aid, a hardener, a thickener and the like are contained. The protective layer contains an appropriate amount of a coating aid, a thickener, a hardener and the like in addition to 1.5 g / m ² of gelatin.

As a method of evaluating the sharpness of a printed image, a resolution chart was brought into close contact with the obtained color photographic paper, exposed with green light, and color developed to obtain a test sheet. This test sheet was measured with a microdensitometer and calculated by a personal computer according to a conventional method to obtain the image sharpness of the magenta layer as MTF (Modula).
Then, the sharpness of the printed image of the support for photographic material was determined.

The results obtained are shown in Table 5.

[0124]

[Table 5]

Note that (Note 6) in Table 5 is as follows.

(Note 6) MTF is indicated by a value of 5 lines / mm.

As is clear from Tables 5 and 3, when a multilayer silver halide color photographic image forming layer was used (Example 39).
.About.42 and Comparative Examples 11 to 12) also obtained the same results as in the case of using the black and white silver halide photographic image forming layer (Examples 24 to 27 and Comparative Examples 7 to 8). In particular, it can be clearly seen that the support for photographic materials in the present invention has a high sharpness of a printed image.

Examples 43 to 52 The procedure of Example 16 was repeated, except that a 2% by weight aqueous solution of methyltrimethoxysilane was added in an amount shown in Table 6 per titanium dioxide.

The results obtained are shown in Table 6.

[0130]

[Table 6]

Note that in Table 6, (Note 4) and (Note 7)
(Note 8) is as follows.

(Note 4) It has the same meaning as that in Table 1.

(Note 7) The treatment amount of the organic surface treatment agent with respect to titanium dioxide on a dry basis is expressed in weight% (as an organic substance content).

(Note 8) As an evaluation method with an emulsion film,
After the development, the emulsion surface was scratched with nails at intervals of 1 cm lengthwise and widthwise to make a cross-shaped scratch, and then the surface was rubbed with running finger in running water to evaluate the degree of peeling of the emulsion layer. The evaluation criteria are as follows. ⊚: The emulsion layer was not peeled off and the film was well attached. ◯: Peeling of the emulsion layer is slight, but there is no practical problem. Δ: Peeling of the emulsion layer is slightly large, but practical use is possible. X: Peeling of the emulsion layer is large, and there is a problem in practical use with the film.

As is apparent from Table 6, the titanium dioxide pigment contained in the surface resin layer of the resin-coated paper-type photographic material support was produced by spray drying and had an apparent density of 0. The support for photographic materials (Examples 43 to 52) using the titanium dioxide pigment of 32 g / cm ³ or more has a high sharpness of a printed image and has good storability of photographic materials, and It can be clearly seen that it is an excellent support in which the releasability of the surface resin layer from the cooling roll is also good. Further, as a titanium dioxide pigment, from the viewpoints of the sharpness of the printed image, the storability of the photographic material, the effect of improving the releasability of the surface resin layer from the cooling roll, and the performance with the emulsion film, the surface treatment amount with an organic substance is used. Is 0.05
It can be clearly seen that the content is preferably in the range of wt% to 4.0% by weight, and particularly preferably in the range of 0.5 to 2.0% by weight.

Examples 53-54 In Example 16, N-β-aminoethyl-γ-aminopropyldimethoxysilane (Example 53) or ε was used instead of the 2% by weight aqueous solution of methyltrimethoxysilane.
2% by weight aqueous solution of caprolactam (Example 54), 1.0% by weight per titanium dioxide (as organic matter content)
The procedure was carried out in the same manner as in Example 16 except that the addition was made, the printed image had high sharpness, the photographic material had good storage stability, and the peelability of the front resin from the cooling roll was good. Supports for photographic materials (Examples 53 to 54) were obtained. The titanium dioxide pigment of Example 53 had an apparent density of 0.40 g / cm ³ , and the titanium dioxide pigment of Example 54 had an apparent density of 0.39 g / cm ³ .

Examples 55-67 In Examples 28-38 and Comparative Examples 9-10, 1.0% by weight of a 2% by weight aqueous solution of methyltrimethoxysilane per titanium dioxide was added to the aqueous slurry before spray drying.
Examples 28 to 38 and Comparative Examples 9 to 10 except for adding (as an organic substance component), thoroughly stirring and mixing, and then spray drying.
The titanium dioxide pigments listed in Table 7 were produced in the same manner as in. The same procedure as in Example 1 was carried out except that these titanium dioxide pigments were used instead of the titanium dioxide pigment used in Example 1. The number average diameter of the titanium dioxide pigment is
It was in the range of 0.122 μm to 0.127 μm.

The results obtained are shown in Table 7.

[0139]

[Table 7]

Note that (Note 4) to (Note 5) in Table 7 have the same meanings as those in Table 4.

As is clear from Table 7, the titanium dioxide pigment contained in the surface resin layer of the resin-coated support for paper-type photographic materials was produced by spray drying and had an apparent density of 0. The support for photographic materials of the present invention (Examples 55 to 67) using a titanium dioxide pigment of 32 g / cm ³ or more has high sharpness of a printed image and good storability of photographic materials, and It can be clearly seen that it is an excellent support in which the releasability of the surface resin layer from the cooling roll is also good. Further, as the titanium dioxide pigment, one having an apparent density of 0.35 g / cm ³ or more is used in terms of the effect of improving the sharpness of the printed image, the storability of the photographic material, and the releasability of the surface resin layer from the cooling roll. Preferably 0.3
It can be clearly seen that those of 8 g / cm ³ or more are particularly preferable.
Further, as the titanium dioxide pigment, from the viewpoint of the effect of the present invention, the surface thereof is calculated in the form of anhydrous metal oxide per titanium dioxide, and preferably 0.25% by weight to 1.5% by weight.
Particularly preferably 0.35% to 1.25% by weight,
It can be clearly seen that it was treated with a hydrous metal oxide containing at least aluminum atoms.

From the comparison between Table 4 and Table 7, it is preferable that the titanium dioxide pigment used in the present invention is an organic surface-treated pigment. Particularly, the effect of the present invention is that the surface of the titanium dioxide pigment is Calculated in the form of anhydrous metal oxide per titanium dioxide, preferably 0.25% by weight to 1.
By using 5% by weight, particularly preferably 0.35% by weight to 1.25% by weight, of a hydrous metal oxide containing at least aluminum atoms, and using an organic surface treatment, It can be seen that it is remarkable.

Examples 68 to 69 Instead of the size press liquid used in Example 1, an amount of a high molecular polyester resin aqueous dispersion liquid (on a Toyo side) in which the coating amount on one side was 2 g / m ² (as dry weight). Spinning Co., Ltd., trade name: Bayronal MD-1930) Optical brightener 0.05
% By weight, blue dye 0.002% by weight, polystyrene sulfonic acid metal salt-based antistatic agent 0.5% by weight and residual weight%
170 g / m 2 having a center surface average roughness of 1.15 μm in the same manner as in Example 1 using the size press liquid consisting of water.
^Two base papers were produced. After that, after the back surface of the base paper is subjected to corona discharge treatment, a thermoplastic polyester resin (manufactured by Eastman Chemical Japan Co., Ltd., trade name: Kodapack-PET 298LB) is used at a resin temperature of 270 ° C. of 25 μm
Melt extrusion coating was carried out in the same manner as in Example 1 with the resin thickness of No. 1 and the running speed of the base paper being 150 m / min. Then, after the surface of the base paper was subjected to corona discharge treatment, a resin composition consisting of 35 parts by weight of the following titanium dioxide pigment master batch and 65 parts by weight of the polyester resin was added at a resin temperature of 270 ° C.
With a resin thickness of 30 μm and a running speed of the base paper of 150 m / min,
Melt extrusion coating is carried out in the same manner as in Example 1, and thereafter the same as in Example 1 or Example 11,
An excellent support for photographic materials having high sharpness of printed images and good storage stability of photographic materials (Examples 68 to 6)
9) was obtained.

As a titanium dioxide pigment masterbatch,
67.5% by weight of the above polyester resin, 30% by weight of the titanium dioxide pigment used in Example 1 or 11 and 2.5% by weight of zinc stearate were added in appropriate amounts to 1,3,5-tris (4-tert. A titanium dioxide pigment masterbatch prepared by thoroughly kneading in the presence of -butyl-3-hydroxy-2,6-dimethyl-benzyl) cyanurate using a twin-screw kneading extruder, cooling and pelletizing was used.

[0145]

According to the present invention, the sharpness of the printed image is high, the storage stability to the silver halide photosensitive layer is remarkably improved, and the releasability from the cooling roll during the production of the support is remarkably improved. It is possible to provide a resin-coated paper-type photographic material support capable of providing a photographic material having excellent gloss without causing uneven peeling.

[Brief description of drawings]

FIG. 1 Definition diagram of peeling angle θ

[Brief description of reference numerals]

 1 Cooling Roll (Cooling Roll) 2 Press Roll 3 Peeling Roll 4 Surface Resin Layer Composition 5 Base (Base Paper Having Back Resin Layer) 6 Die 7 Peeling Angle θ

Claims (17)

[Claims] 1. A support for a photographic material, comprising a substrate comprising a paper mainly composed of natural pulp as a substrate, and a paper substrate surface on one side on which a photographic image forming layer is provided is coated with a thermoplastic resin (A) layer, The thermoplastic resin (A) layer contains at least a thermoplastic resin and a titanium dioxide pigment, and the titanium dioxide pigment is produced by spray drying, and is determined according to JIS K 5101-1991. A support for a photographic material, which has an apparent density (static method) of 0.32 g / cm ³ or more. 2. The titanium dioxide pigment is JIS K 510.
The support for photographic materials according to claim 1, which has an apparent density (static method) of 0.35 g / cm ³ or more as determined according to 1-1991. 3. The titanium dioxide pigment is JIS K 510.
The support for photographic materials according to claim 1, which has an apparent density (static method) of 0.38 g / cm ³ or more in accordance with 1-1991. 4. A titanium dioxide pigment whose surface comprises at least 0.25% by weight to 1.5% by weight, calculated as anhydrous metal oxides per titanium dioxide, of at least aluminum atoms and a silicon dioxide content of 0. The support for photographic materials according to claim 1, 2 or 3, which has been treated with a hydrous metal oxide of 0.4% by weight or less (including 0). 5. The titanium dioxide pigment has a surface of 0.35% by weight to 1.25% by weight, calculated as anhydrous metal oxide per titanium dioxide, containing at least aluminum atoms and having a silicon dioxide content of 0. 5. It has been treated with a hydrous metal oxide of 0.4% by weight or less (including 0).
A support for the photographic material described. 6. The support for photographic materials according to claim 4, wherein the hydrous metal oxide is hydrous aluminum oxide and hydrous silicon oxide. 7. The support for photographic materials according to claim 4, wherein the hydrous metal oxide is hydrous aluminum oxide. 8. A support for photographic materials according to claim 1, 2, 3, 4, 5, 6 or 7, wherein the titanium dioxide pigment is produced by an external seed method. 9. The titanium dioxide pigment has a particle size of 0.11 as a number average particle size measured by directional measurement with an electron microscope.
0 to 0.150 μm.
The support for photographic materials according to 4, 5, 6, 7 or 8. 10. A titanium dioxide pigment whose surface is treated with an organic substance in an amount of 0.05% by weight to 4.0% by weight based on titanium dioxide.
A support for a photographic material according to 6, 7, 8 or 9. 11. A support for photographic materials according to claim 10, wherein the surface of the titanium dioxide pigment is treated with an organic substance in an amount of 0.3 to 2.0% by weight based on titanium dioxide. 12. The titanium dioxide pigment having an anatase structure according to claim 1, 2, 3, 4, 5, 6, 7, 8,
The support for photographic materials according to 9, 10 or 11. 13. The thermoplastic resin (A) is a polyolefin-based resin, a polyester-based resin or a mixture thereof, 1, 2, 3, 4, 5, 6, 7, 8, 9, 1.
The support for photographic materials according to 0, 11 or 12. 14. The support for photographic materials according to claim 13, wherein the polyolefin resin is a polyethylene resin. 15. The paper substrate surface opposite to the side coated with the thermoplastic resin (A) layer is coated with the resin (B) capable of forming a film. 4,
5, 6, 7, 8, 9, 10, 11, 12, 13 or 1
4. A support for photographic materials as described in 4. 16. The support for photographic materials according to claim 15, wherein the resin (B) capable of forming a film is a polyolefin resin, a polyester resin or a mixture thereof. 17. The photographic material support according to claim 16, wherein the polyolefin resin is a polyethylene resin.