JPH0441177B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a photographic masterbatch, and more particularly to a method for manufacturing a photographic resin-coated paper containing very little micro grit using the photographic masterbatch. The essential structure of photographic resin-coated paper containing a photographic masterbatch in the resin layer is already known; for example, as disclosed in U.S. Pat. No. 3,501,298, both sides of the paper base are coated with resin. In this method, a titanium dioxide pigment, a blue pigment, a fluorescent whitening agent, etc. are contained in the resin layer on the emulsion-coated side. However, the actual situation is that sufficient measures have not yet been taken to effectively prevent the generation of microgrit in the manufacturing method of resin-coated paper for photographs. The term "microgrit" as used herein refers to minute foreign matter or minute grains that appear on the surface of the coated resin in photographic resin-coated paper in which at least one side of the paper or synthetic paper substrate is coated with a resin composition. There are various causes of microgrit, but for example, the microgrit that appears on photographic resin-coated paper manufactured by melt-extruding photographic resin onto at least one side of a paper or synthetic paper substrate using a melt extruder is the cause of microgrit. (1) Regarding the resin itself used,
If a lot of gel is generated, (2) when the molten resin is extruded into a film from the melt extruder through the die,
(3) If the screen attached to the breaker plate in the melt extruder is dirty; (4) There is a crack in the barrel liner in the melt extruder. (5) Insufficient bending in the melt extruder, but these can often be resolved relatively easily by skilled engineers. However, the most difficult countermeasure against microgrit is when microgrit occurs in photographic resin-coated paper in which the paper or synthetic paper substrate is coated with a resin composition consisting of at least a resin and a pigment. In the first place, the method of incorporating pigments into resin is to create a so-called master batch in which pigments are included in resin at a certain concentration in advance, and then dilute and mix them with diluted resin to the desired ratio.
It is usual to prepare and use a so-called compound in which a desired composition ratio of pigment is contained in a resin from the beginning. However, when preparing a masterbatch or compound by melt-kneading resin and pigment using an ordinary melt-kneading machine such as a Banbury mixer or kneader, relatively coarse pigment particles in the resin may be in a fine state. There is a tendency for pigment particles to be dispersed as they are without being dispersed, and thus undispersed pigment particles will be present in the masterbatch or compound. As a result, at least one surface of the paper or synthetic paper substrate is coated with a resin composition comprising at least a pigment and a resin produced using the masterbatch or the compound. Micro grit will be generated. The occurrence of microgrit in resin-coated papers used as photographic supports causes serious photographic defects. That is, when a person is photographed on a photographic paper having a resin-coated paper containing microgrit as a photographic support, if microgrit appears in areas such as the face, the photograph has no commercial value. As a result of various studies to improve these points, the present inventors have developed a photographic masterbatch consisting of at least a resin and a titanium dioxide pigment, which does not substantially contain an antioxidant. A titanium dioxide pigment-containing resin composition prepared in advance at a titanium dioxide pigment-containing concentration higher than that of the titanium dioxide pigment-containing concentration is lower than the titanium dioxide pigment-containing concentration of the titanium dioxide pigment-containing composition, and the titanium dioxide pigment-containing concentration is lower than that of the resin composition used. The generation of microgrit by applying a photographic masterbatch diluted with diluted resin to a concentration higher than the titanium dioxide pigment content to a photographic resin-coated paper extrusion coated on one side of a paper or synthetic paper substrate. The inventors have discovered that this can be significantly suppressed, leading to the present invention. Incidentally, "substantially no antioxidant" means that it does not actively prevent resin deterioration caused by the antioxidant in the masterbatch manufacturing process of the present invention, and the concentration of the antioxidant is
Never exceed 5ppm. It has been found that the effect is particularly significant when the resin used to dilute the photographic masterbatch has a melting index of 2 to 9. Up until now, the titanium dioxide pigment-containing photographic masterbatch used for photographic resin-coated paper usually has a titanium dioxide pigment concentration of 20 to 40% by weight.
Depending on the quality of the photographic resin-coated paper required, a diluted resin may be appropriately added to form a resin composition containing the desired titanium dioxide pigment content, which is then applied to at least one side of the photographic resin-coated paper. was being carried out. However, when photographic resin-coated paper is produced by such a conventional method, microgrit is often generated, often resulting in deterioration in quality. However, in a photographic masterbatch comprising at least a resin and a titanium dioxide pigment, <a titanium dioxide pigment-containing composition substantially free of antioxidant and prepared in advance at a titanium dioxide pigment content concentration higher than that of the photographic masterbatch. ＞(hereinafter＜＞
The content of the titanium dioxide pigment is lower than the titanium dioxide pigment content concentration in <the high concentration master patch>, and the titanium dioxide pigment content is contained in the resin composition used. A photographic masterbatch diluted with a diluted resin to a higher concentration than that of a photographic masterbatch] (hereinafter, the part in brackets may be abbreviated as a low-density masterbatch) is applied to at least one side of a paper or synthetic paper substrate. Therefore, it was found that the generation of microgrit was significantly suppressed. The high-density masterbatch referred to in the present invention is once diluted with a diluting resin to form a low-density masterbatch, and the photographic masterbatch is particularly melted with a melting index of 2 to 9.
When extrusion coating is applied to at least one side of a paper or synthetic paper substrate after dilution with a diluted resin, the concentration of titanium dioxide pigment normally used is approximately 20 to 40%.
The reason why the generation of microgrit is significantly suppressed compared to when a masterbatch is extruded and coated on at least one side of a paper or synthetic paper substrate is not yet clear, but after changing a high-density masterbatch to a low-density masterbatch, This may be due to a special effect in combination with a diluted resin with a melting index of . The melt index in the present invention has the same meaning as the melt index (MI) described in Plastic Materials Course "Polyethylene Resin" 7th Edition, co-authored by Oka and Yamagata, published by Nikkan Kogyo Shimbun, pp. 44-45. Incidentally, the generation of microgrit tends to be more likely to occur when the pigment in the masterbatch also contains ultramarine blue than when the pigment in the masterbatch contains titanium dioxide pigment alone. In the photographic industry, it is essential to apply ultramarine blue to the resin layer of resin-coated photographic paper in order to achieve a white appearance through so-called bluing, so an immediate solution is desired. was. The present invention provides a photographic masterbatch containing not only titanium dioxide pigment alone but also ultramarine blue.
Particularly good results are obtained when applied to photographic resin-coated papers according to the invention. As the ultramarine blue used in the present invention, any commonly commercially available ultramarine blue can be used as long as it does not cause any problems when applied to photographic resin compositions. For example, Aokuchi Gunjo No.8000, No.4000, No.3000, No.2000, Akakuchi Gunjo No.1900, No.1500, No.300, processed Gunjo No.3000A manufactured by Daiichi Kasei Kogyo Co., Ltd.,
No.1500A, PB-80, DV-1, DV-2, etc., and in some cases, CB-80, CR-50, DR-
1. Cosmetic ultramarine blues such as DP-3 can also be used. In addition, various types of ultramarine may be used in appropriate combination to produce a desired color. In the present invention, the amount of ultramarine contained in 100 parts by weight of the resin composition is preferably 0.05 to 10 parts by weight.
If it exceeds 10 parts by weight, the generation of microgrit will increase significantly, and if it is less than 0.05 parts by weight, the blue tinting effect will not be exhibited well. In the present invention, the pigment concentration in the high concentration masterbatch is preferably 40 to 80% by weight, and the pigment concentration in the low concentration masterbatch is preferably 20 to 60% by weight. The titanium dioxide pigments used in the practice of the present invention include those produced by the sulfuric acid method, those produced by the chlorine method,
Further, although either rutile type or anatase type may be used, the anatase type is advantageous in terms of whiteness.
In addition, titanium dioxide pigments without surface treatment can be used, titanium dioxide pigments coated with an inorganic surface treatment agent such as hydrous aluminum oxide, or organic surface treatment agents such as organopolysiloxane can be used. It is also possible to use a surface treated with a surface treatment agent, or a combination of an inorganic surface treatment agent and an organic surface treatment agent as appropriate. Photographic masterbatch in the present invention (hereinafter referred to as
The resin used for MB (sometimes abbreviated as MB) is
Any thermoplastic resin that can be melt-extruded may be used, but polyolefin resins are particularly preferred, such as polypropylene, high-density polyethylene, medium-density polyethylene, and low-density polyethylene, or two or more of these resins as appropriate. Although they can be used in combination, low density polyethylene resin is particularly preferred. The diluting resin in the present invention has a melting index of 2 to 2.
A polyolefin resin of No. 9 is used. For example, polypropylene, polyethylene, etc. are used, and polyethylene is particularly preferred. As the polyethylene resin, high-density polyethylene, medium-density polyethylene, low-density polyethylene, etc. may all have a melting index of 2 to 9, or two or more of these resins may be used in combination. The concentration of the titanium dioxide pigment used in the photographic resin composition of the present invention to be contained in the resin layer of the photographic resin-coated paper is 5% by weight or less based on the resin, so that it has no hiding power as a photographic support. On the other hand, if it exceeds 40% by weight, the fluidity etc. decreases, which is not preferable, and particularly preferably 7.5% by weight or more.
It is in the range of 25% by weight. The resin layer of the photographic resin-coated paper of the present invention may contain a fatty acid metal salt. Examples of these fatty acid metal salts include zinc stearate, calcium stearate, aluminum stearate, magnesium stearate, zirconium octylate, sodium palmitate, calcium palmitate, and sodium laurate. In addition, the amount added is 0.01 to 5 to the resin composition containing the titanium dioxide pigment.
A weight percent range is preferred. In the photographic resin composition of the present invention, white pigments such as zinc oxide, talc, and calcium carbonate, coloring pigments such as cobalt blue, cobalt violet, and deep blue, and fluorescent whitening agents may be added as necessary. It's okay. The photographic resin-coated paper in the present invention is a paper or a synthetic paper base (hereinafter simply referred to as base paper) that normally runs.
It is manufactured by melt-extruding and coating at least one surface of a heated and melted resin composition into a film using a slit die. Usually the melt extrusion temperature is 200℃~
Preferably the temperature is 350°C. In addition, before coating the resin composition on the base paper, the base paper is subjected to corona discharge treatment.
It is preferable to perform activation treatment such as fire treatment.
There is no particular limit to the thickness of the resin layer of the resin-coated paper, but it is generally advantageous to extrude coat it to a thickness of about 5 microns to 50 microns. In addition, in ordinary resin-coated paper in which both sides of the base paper are coated with resin, the resin surface containing titanium dioxide pigment has a glossy surface, a matte surface, a silky surface, etc. depending on the use. The opposite back surface is usually a matte surface, and the front surface or both front and back surfaces can be subjected to activation treatment such as corona discharge treatment or fire treatment if necessary. The base paper used in the practice of the present invention may be ordinary natural pulp paper, synthetic fiber, or so-called synthetic paper made from synthetic resin film.
Natural pulp paper based on wood pulp of softwood pulp, hardwood pulp, softwood hardwood mixed pulp is advantageously used. Further, there is no particular restriction on the thickness of the base paper, but a base paper with good surface smoothness is preferred, and its basis weight is preferably 50 to 250 g/m ² . The base paper mainly composed of natural pulp, which is advantageously used in the practice of the present invention, can contain various polymer compound additives. For example, dry paper strength enhancers include cationized starch, cationized polyacrylamide, anionized polyacrylamide, carboxy-modified polyvinyl alcohol, gelatin, etc. Sizing agents include fatty acid salts, rosin derivatives, dialkyl ketene dimer emulsions, petroleum resin emulsions, etc. , ammonium salt of styrene-maleic anhydride copolymer alkyl ester, clay, kaolin, calcium carbonate,
Wet paper strength enhancers such as barium sulfate and titanium oxide; melamine resins, urea resins, and epoxidized polyamide resins; fixing agents such as polyvalent metal salts such as aluminum sulfate and aluminum chloride; and cationically modified polymers such as cationized starch. , pH regulators such as caustic soda, soda carbonate, and hydrochloric acid; inorganic electrolytes such as common salt and mirabilite; in addition, dyes, fluorescent whitening agents, latex, and the like may be contained in appropriate combinations. The photographic resin-coated paper of the present invention can be provided with various silver halide photographic emulsion layers.
For example, silver chloride, silver bromide, silver chlorobromide, silver iodobromide,
A silver chloroiodobromide emulsion layer can be provided. Also,
A multilayer silver halide photographic constituent layer can be provided by containing a color coupler in the silver halide photographic emulsion layer. As the binder for these silver halide emulsion layers, in addition to ordinary gelatin, hydrophilic polymeric substances such as polyvinylpyrrolidone, polyvinyl alcohol, and polysaccharide sulfate ester compounds can be used. Further, the above-mentioned silver halide emulsion layer can contain various additives. For example, sensitizing dyes include cyanine dyes and merocyanine dyes; chemical sensitizers include water-soluble gold compounds and sulfur compounds; antifoggants and stabilizers include hydroxy-triazolopyrimidine compounds and mercapto-heterocyclic compounds. Hardeners such as formalin, vinyl sulfone compounds, aziridine compounds, coating aids such as benzene sulfonate, sulfosuccinate salts, anti-staining agents, dialkylhydroquinone compounds, etc., development accelerators, etc.
Hydroquinone, phenidone, etc., as ultraviolet absorbers, benzotriazole compounds, etc., as well as fluorescent whitening agents, sharpness-improving dyes, antistatic agents, PH regulators, and water-soluble iridium compounds and water-soluble iridium compounds during the production and dispersion of silver halide. Rhodium compounds and the like can be contained in appropriate combinations. Further, on the back side of the photographic resin-coated paper in the present invention, that is, on the support surface opposite to the side on which the photographic constituent layer, in most cases the silver halide photographic constituent layer, is coated, anti-curl, antistatic, etc. A coating layer consisting of a hydrophilic colloid layer called a back coat layer can be provided for the purpose of preventing adhesion and slipping. Such a back coat layer may contain a binder, a protective colloid, a curing agent, an antistatic agent, a surfactant, a matting agent, a latex, and the like. Next, in order to explain the present invention more specifically,
An example will be described. Example 1 Low density polyethylene (density 0.92g/cm ³ , MI=
8) Place 15 parts by weight in a Banbury mixer, add the amount of titanium dioxide pigment, amount of ultramarine, and amount of zinc stearate listed in Table 1, Note 1, and heat at 150°C.
The mixture was thoroughly kneaded to obtain high-concentration masterbatches containing pigments and the like. Low-density polyethylene (density 0.92 g/cm ³ ,
MI=8) and then melt-extruded using a vented extruder to obtain the low-concentration masterbatch shown in Table 1, Note 2. Separately, a master batch for comparison was created as follows. That is, 57.5 parts by weight of the same low-density polyethylene used in Sample No. 4 was placed in a Banbury mixer, and 40 parts by weight of titanium dioxide pigment,
0.5 parts by weight of ultramarine blue and 2 parts by weight of zinc stearate (both of which were the same as those used in Samples Nos. 1 to 7) were added and kneaded well at 150°C to obtain a comparative masterbatch containing pigments, etc. (Sample No.8
). On the other hand, a mixed stock of 50 parts by weight of bleached hardwood kraft pulp and 50 parts by weight of bleached softwood sulfite pulp was prepared using Canadian Standard Freeness 310.
ml, and further added to 100 parts by weight of pulp, 3 parts by weight of cationized starch, 0.2 parts by weight of anionized polyacrylamide, 0.4 parts by weight of alkyl ketene dimer emulsion (as ketene dimer content), and 0.4 parts by weight of polyaminopolyamide epichlorohydrin resin. A paper with a basis weight of 160 g/m ² was made.
The obtained wet paper paper was dried at 110°C and then impregnated with an impregnating solution consisting of 3 parts by weight of carboxy-modified polyvinyl alcohol, 0.05 parts by weight of a fluorescent brightener, 0.002 parts by weight of blue dye, 0.2 parts by weight of citric acid and 97 parts by weight of water. of
It was impregnated with 25 g/m ² , dried with hot air at 110° C., and calendered at a linear pressure of 90 Kg/cm, followed by corona discharge treatment on both sides to produce a base paper for photographic resin-coated paper. Next, apply high-density polyethylene (density
A 1:1 mixture of 0.96g/cm ³ , MI=5) and low density polyethylene (density 0.92g/cm ³ , MI=5) was heated to resin temperature.
It was coated to a thickness of 30μ using a melt extrusion coater at 330°C. Next, write Table 1 Note 2 on the surface of the base paper.
After thoroughly mixing a resin composition consisting of 25 parts by weight of the listed MB and 75 parts by weight of low-density polyethylene for dilution listed in Note 3 of Table 1, the resin composition was melt-extruded using a screw type extruder with an extrusion opening diameter of 65 mm and a T-die with a width of 750 mm. Using a machine, apply the resin to a thickness of 30μ at a resin temperature of 320℃.
Resin coated papers containing titanium dioxide pigment etc. were produced respectively. At that time, the surface resin layer containing titanium dioxide pigment etc. was processed into a flat glossy surface, and the back resin layer was processed into a paper-like matte surface. The number of microgrits was visually counted by counting the number of microgrits generated on the resin surface containing titanium dioxide pigment etc. of the photographic resin-coated paper produced by the method described above. The results obtained are shown in Table 1.

[Table] From Table 1, it can be seen that the high concentration masterbatch referred to in the present invention is a low concentration masterbatch with a melting index (MI) of 2.5 to 9 in the resin composition combined with the low density polyethylene for dilution described in Note 3. It can be seen that certain samples Nos. 1 to 5 all have little microgrit generation. In addition, samples No. 6 and No. 7 whose MI of low-density polyethylene for dilution is 12 and 20 are No.
It can be seen that more microgrit is generated than in samples 1 to 5. On the other hand, when a low-density masterbatch was prepared from the beginning, even if the diluent resin had an MI of 8, microgrots were generated significantly, and the paper was unsuitable as a photographic resin-coated paper. Example 2 Resin, titanium dioxide pigment, ultramarine blue and magnesium stearate were placed in a Banbury mixer so that the contents were as shown in Table 2, note 4, and
The mixture was thoroughly kneaded at 150°C to obtain high-concentration masterbatches containing pigments and the like. Medium-density polyethylene (density 0.93, MI=
6) and then melt-extruded using a kneading extruder to obtain the low-concentration masterbatches listed in Table 2, Note 5. Separately, a master batch for comparison was created as follows. That is, 76.5 parts by weight of the same medium density polyethylene used in Samples No. 10 to No. 14 was placed in a Banbury mixer, and titanium dioxide pigment was added to it.
20 parts by weight, 2.5 parts by weight of ultramarine, and 1 part by weight of magnesium stearate (all of these are sample No. 10~
Add the same ingredients used for No. 14) and heat to 150℃.
The mixture was thoroughly kneaded to obtain a comparative masterbatch containing pigment, etc. (referred to as sample No. 15). The procedure was the same as in Example 1, except that the resin composition used in melt extrusion using the extruder described in the Example was as shown in Table 2, Note 6. The results obtained are shown in Table 2.

[Table] Table 2 shows that in a resin composition in which the high concentration masterbatch referred to in the present invention is used as a low concentration masterbatch in combination with the low density polyethylene for dilution described in Note 6, the ultramarine blue content in the high concentration masterbatch is 0.05 to 0.05. 10 parts by weight (sample No. 10 to No. 13)
It can be seen that the generation of microgrit is small in both cases. On the other hand, the high-concentration masterbatch with an ultramarine content of 15 parts by weight (sample No. 14) and the comparative masterbatch (sample No. 15) have an ultramarine blue content of 15 parts by weight, even if the MI of the low-density polyethylene for dilution is 3. Even then, a large amount of microgrit was generated, making it unsuitable as a photographic resin-coated paper. Example 3 55.6 parts by weight of the low-density polyethylene listed in Table 2, Note 6 in Samples No. 12 and No. 15 of Example 2 was added to 30.6 parts by weight of the low-density polyethylene and high-density polyethylene (density 0.97, MI = 7) 25 Samples No. 12 and No. 15 of Example 2 were carried out in the same manner as Samples No. 12 and No. 15 except that the parts by weight were changed, and the same results as in Example 2 were obtained.

Claims (1)

[Scope of Claims] 1. A photographic masterbatch comprising at least a resin and a titanium dioxide pigment, the photographic masterbatch containing substantially no antioxidant and prepared in advance at a concentration higher than that of the titanium dioxide pigment in the photographic masterbatch. A titanium pigment-containing resin composition is diluted with a diluting resin so that the titanium dioxide pigment content concentration is lower than the titanium dioxide pigment content concentration of the titanium dioxide pigment-containing composition and lower than the titanium dioxide pigment content concentration of the resin composition used. A method for manufacturing a photographic masterbatch, which is characterized in that it is made high. 2. The titanium dioxide pigment content concentration of the titanium dioxide pigment-containing resin composition is prepared in advance to be higher than the titanium dioxide pigment content concentration of the photographic masterbatch.
A method for producing a photographic masterbatch according to claim 1, wherein the content is 40 to 80% by weight. 3. The method for producing a photographic masterbatch according to claim 1, wherein the titanium dioxide pigment content of the photographic masterbatch is 20 to 60% by weight. 4. A photographic masterbatch according to claim 1, containing 0.05 to 10 parts by weight of ultramarine in 100 parts by weight of a titanium dioxide pigment-containing resin composition prepared in advance at a concentration higher than that of the photographic masterbatch. Manufacturing method. 5 On at least one side of the paper or synthetic paper substrate,
In a method for producing a photographic resin-coated paper in which a photographic masterbatch comprising at least a resin and a titanium dioxide pigment is diluted with a diluent resin and coated with a resin composition comprising at least a resin and a titanium dioxide pigment, the photographic masterbatch is , a titanium dioxide pigment-containing resin composition prepared in advance to have a higher titanium dioxide pigment concentration than that of the photographic masterbatch without substantially containing an antioxidant is diluted with a diluting resin to increase the titanium dioxide pigment concentration to the titanium dioxide pigment concentration. A method for producing resin-coated paper for photography, characterized in that the concentration of titanium dioxide pigment is lower than the concentration of titanium dioxide pigment in the titanium pigment-containing composition, but higher than the concentration of titanium dioxide pigment in the resin composition coating the paper or synthetic paper substrate. . 6. A patent claim in which the titanium dioxide pigment content of the titanium dioxide pigment-containing resin composition, which is prepared in advance to be higher than the titanium dioxide pigment content concentration of the photographic masterbatch used for the photographic resin-coated paper, is 40 to 80% by weight. A method for producing a photographic resin-coated paper according to Scope 5. 7 The titanium dioxide pigment content concentration of the photographic masterbatch used for the photographic resin-coated paper is 20
60% by weight of the photographic resin-coated paper according to claim 5. 8. Scope of Claims: 0.05 to 10 parts by weight of ultramarine is contained in 100 parts by weight of a titanium dioxide pigment-containing resin composition prepared in advance at a titanium dioxide pigment concentration higher than that of the photographic masterbatch used in the photographic resin-coated paper. A method for producing a photographic resin-coated paper according to item 5. 9 The concentration of titanium dioxide pigment in the resin composition used during the production of the photographic resin-coated paper is 5 to 5.
A method for producing photographic resin-coated paper according to claim 5, wherein the content is 20% by weight. 10 The diluent resin for diluting the photographic masterbatch used in the photographic resin-coated paper to the titanium dioxide pigment content of the resin composition coating the substrate is a polyolefin resin having a melting index of 2 to 9. A method for producing a photographic resin-coated paper according to Scope 5.