JPH0481835A - Base for photographic paper - Google Patents

Abstract

PURPOSE:To produce the bright surface photographic paper which has sufficient smoothness and is advantageous in terms of cost by specifying the internal bonding strength of raw paper to a specific value and subjecting the paper to a calender treatment between metallic rolls and synthetic resin rolls. CONSTITUTION:The internal bonding strength of the raw paper is increased by using the pulp produced from needle-leaf trees and the internal bonding strength of the raw paper is decreased by using the pulp produced from broadleaf trees. The internal bonding strength of the raw paper is adjusted to 1.2 to 1.8kg.cm by selecting the kinds of the pulp and the kinds of additives and adjusting the amts. of these materials to be used. The paper is liable to be cut if the internal bonding strength is small. The effective surface improving effect is not obtainable if the internal bonding strength is large. The material of the synthetic resin rolls of the calender treatment between the metallic rolls and the synthetic resin rolls to be executed during coiling after drying of the raw paper is selected from synthetic resins, such as polyester. The moisture of the raw paper at the time of the calender treatment is preferably 6.0 to 9,0% and the surface temp. of the synthetic resin rolls is set at 50 to 250 deg.C. The base for photographic paper is produced by coating both surfaces of such raw paper with polyolefin.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a support for photographic Inzai paper, and particularly to a support for photographic paper with good surface smoothness.

(Prior Art) In recent years, for the purpose of rapid development of photographic paper, water-resistant photographic paper supports in which both sides of the paper are coated with polyolefin such as polyethylene have been preferably used.

Among photographic paper supports made of base paper coated on both sides with polyolefin, there are those whose surfaces are glossy and those whose surfaces are patterned such as matte or open holes. Among these, those with no patterns at all and a smooth, glossy surface are said to be good, and in particular, those with mirror-like smooth surfaces with as few minute irregularities as possible on both sides are said to be good.

In order to obtain such a smooth support, for example, the amount of voids with pores of 0.4 μm or less in the base paper constituting the support is 0.0
Use pulp of 4d/g or more (Japanese Patent Application Laid-Open No. 60-6
7940), using wood pulp with an average fiber length of 0.4 to 0.9 cm, an average fiber thickness of 13.5 μm or more and an average fiber thickness of 4 μm or less (Japanese Patent Application Laid-open No. 60-69649), hydrophobic to natural pulp. Use a mixture of 5 to 60% fiber (Japanese Patent Application Laid-Open No. 61-275752), or limit the dehydration conditions when obtaining wet paper from pulp slurry using a two-wire paper machine (Japanese Patent Application Laid-open No. 61-284762). Other proposals have been made. Furthermore, the density of the base paper used as a support for photographic printing paper is increased by calendering the base paper between metal rolls and increasing the pressure at this time, that is, the pressure of the machine calender. There is. On the other hand, extrusion coating is generally used to coat polyolefins such as polyethylene, in which polyolefin melted at high temperature is cast onto the surface of base paper. In order to improve the properties, measures have been taken such as increasing the thickness of the coating polyolefin layer or increasing the pressing pressure when coating the polyolefin.

However, the above-mentioned measures when coating polyolefin have the problem of being small in effectiveness and disadvantageous in terms of cost.On the other hand, the above-mentioned method of increasing the density of the base paper by machine calendering also These methods have the disadvantage of being susceptible to appearance defects, and no satisfactory smooth support for photographic paper has been obtained by any of the methods.

In other words, if there are irregularities on the base paper, it goes without saying that there are irregularities on the front side of the base paper, but even if the front side of the base paper is smooth, if there are irregularities on the back side, the unevenness on the back side will be affected. Depending on the degree of extrusion coating with polyolefin, the effects of these irregularities on the back surface appear on the front surface, resulting in the problem that a smooth surface that can be used as a support for photographic printing paper cannot be obtained.

By the way, recently it has been discovered that there are two types of irregularities on base paper: large wave-like irregularities with a period of around 5 seconds and small dot-like irregularities with a period of around 0.5 seconds, and that base paper is simply rolled on a metal roll. Although it is possible to remove the above-mentioned wavy irregularities by machine calendering between the rolls, it is difficult to remove the dotted irregularities without causing brushing etc. It has been found that when supercalendering is performed between rollers, it is possible to remove dotted irregularities, but it is difficult to remove wavy irregularities.

Furthermore, since the rolls of supercalenders are easily damaged, it is difficult to use them on-machine and is disadvantageous in terms of cost.

(The invention aims to solve [i!]) The above-mentioned problems with water-resistant photographic paper can be solved by using base paper that has been calendered with metal rolls/synthetic resin rolls instead of the conventional supercalender. (Japanese Patent Application No. 1-22284) However, even with the above-mentioned calender treatment using metal rolls/synthetic resin rolls, depending on the type of base paper to be calendered, the flatness may not be sufficiently improved, or polyolefin Appearance failure may occur during coating.

As a result of intensive studies aimed at solving the above drawbacks, the inventors of the present invention discovered that the above problems were caused by the magnitude of the internal bonding force of the base paper, and arrived at the present invention.

Accordingly, an object of the present invention is to provide a support for photographic paper that has sufficient smoothness, is free from blacking and paper curls, and is advantageous in terms of manufacturing cost.

(Means for Solving the Problems) The above-mentioned object of the present invention is to provide a support for photographic paper in which both sides of a base paper are coated with polyolefin, the base paper having an internal bonding strength of 1.2 to 1.8 kg-elm. This has also been achieved by using a support for photographic paper, which is characterized by being a base paper that has been calendered between a metal roll and a synthetic resin roll.

The present invention will be explained in more detail below.

The base paper used for the support for photographic paper according to the present invention is obtained by making paper from a stock containing natural pulp obtained from coniferous trees, hardwood trees, etc. as the main raw material, and various chemicals described below added thereto. Generally, by using valves made from coniferous trees such as NBKP, the internal bonding strength of the base paper increases and L
By using bulbs made from hardwoods such as BSP and LDP, the internal bonding strength of the base paper can be reduced.

The above internal bonding force is Tambi Useful Method 403
(Tappi useful Method 403
), and is considered to represent the bonding strength between fibers in the thickness direction of paper.

In the present invention, a synthetic valve may be used instead of the natural valve, or a base paper containing a mixture of a natural valve and a synthetic valve in an arbitrary ratio may be used.

Further, in order to make the present invention more effective, it is preferable to use bulbs having an α-cellulose content of 90% or more at 25% by weight or more, more preferably 50% by weight or more.

Also, the freeness of the valve is 200 to 500cc.

S, F, is preferred, especially 250 to 350ccC,S,
F, is preferred.

Additive chemicals include clay, talc, calcium carbonate, fillers such as urea resin particles, rosin, alkyl ketene dimers, higher fatty acid salts, paraffin wax, sizing agents such as alkenylsuccinic acid, paper strength agents such as polyacrylamide, and sulfuric acid bands. , a fixing agent such as aluminum chloride, etc. are used.

In addition, dyes, fluorescent dyes, slime control agents, defoaming nets, etc. are added as necessary. Furthermore, the following softeners may be added as necessary.

Softeners are described, for example, in Shin Paper Processing Handbook (edited by Shigyo Times), pages 554-555, published in 1980. Among these, those with a molecular weight of 200 or more are preferred, and those with an amine salt or quaternary ammonium salt that grow a hydrophobic group having a carbon number of 10 or more or self-fix with cellulose are particularly preferred. Specific examples of agents include reaction products of maleic anhydride copolymer and polyalkylene polyamine, reaction products of higher fatty acids and polyalkylene polyamines, reaction products of urethane alcohol and alkylating agents, and quaternary ammonium of higher fatty acids. Examples include salt. Among these, particularly preferred are reaction products of maleic anhydride copolymer and polyalkylene polyamine, and reaction products of urethane alcohol and alkylating agent.

The surface of the base paper can also be subjected to surface size treatment using a film-forming polymer such as gelatin, starch, carboxymethyl cellulose, polyacrylamide, polyvinyl alcohol, or a modified product of polyvinyl alcohol. Examples of polyvinyl alcohol modified products in this case include carboxyl group modified products, silanol modified products, and copolymers with acrylamide. In addition, when surface size treatment is performed using a film-forming polymer, the coating amount of the film-forming polymer is as follows:
0.1~5.0g/i, preferably 0゜5~2.0g
/rrf. Furthermore, an antistatic agent, a fluorescent whitening agent, a pigment, etc. can be added to the film-forming polymer at this time, if necessary.

Among these various additives, paper strength enhancers or surface sizing agents are used to increase the internal bonding strength of the base paper, while sizing agents, softeners, fillers, etc. are used to reduce the internal bonding strength of the base paper. You can force it.

In the present invention, the internal bonding strength of the base paper can be increased from 1°2 to 1.8 kg-1 by selecting the types of the valves described above and the types of the various additives described above, and adjusting their usage amounts.
Preferably, it is adjusted to 1.4 to 1.6 kg-cm.

If the internal bonding force is less than 1.2 kg-cm, not only will the paper become easy to cut, but also microscopic fractures will occur on the surface of the base paper layer during the gap between the polyolefin resin coating and peeling off from the cooling roll (due to blistering). ), which causes appearance failures. Furthermore, if the internal bonding force is greater than 1.8 kg-cm, no effective flatness improvement effect can be obtained even if calender treatment is performed using metal rolls/synthetic resin rolls, which will be described later.

The base paper is made by making a valve slurry containing the above-mentioned valves and additives such as filler, sizing agent, paper strength reinforcing agent, and fixing agent added as necessary using a paper machine such as a summary paper machine, and drying the slurry. Manufactured by winding. The surface size treatment is performed either before or after this drying, and the calendering treatment described below is performed after drying or between winding.

If the surface sizing treatment is performed after drying, this calendering treatment can be carried out either before or after the surface sizing treatment, but it is particularly preferably carried out in the final finishing step after various treatments have been carried out.

The calender treatment according to the present invention is performed between a metal roll and a synthetic resin roll (soft calender treatment).

Brushing occurs when attempting to obtain sufficient smoothness by simply performing machine calendering instead of the above calendering process until the density of the base paper reaches 1.06 g/ci or higher. The appearance of the resulting base paper is impaired. Furthermore, if the density of the base paper is less than 1.06 g/d, the above-mentioned dotted irregularities cannot be removed, and photographic paper with good smoothness, which is the object of the present invention, cannot be obtained. However, if only supercalender treatment is performed, there is a limit to the thickness of the base paper that can be adjusted, and the above-mentioned wavy irregularities cannot be removed, making it impossible to achieve the object of the present invention.

On the other hand, in the case of calender treatment using a synthetic resin roll employed in the present invention, both the wavy irregularities and dotted irregularities can be removed.

In this case, from the viewpoint of adjusting the thickness and further enhancing the effect of removing wavy irregularities, it is preferable to further perform a calendering process between metal rolls after the soft calendering process.

The material of the synthetic resin roll used in the present invention is appropriately selected from synthetic resins such as urethane, ebonite, nylon, amide, isocyanurate, and polyether. In particular, it is preferable to use polyether synthetic resin.

The hardness, expressed in Shore hardness, is preferably 60 to 98, particularly preferably 75 to 93.The water content of the base paper during calendering is preferably 6.0% to 9.0%, and the synthetic resin roll The surface temperature is preferably 50°C to 250°C, particularly 70°C to 150°C.

Also, the base paper density is 0.0 between the metal roll and the synthetic resin roll.
Calendar treatment is performed so that the density is 70 to 1.00 g/cj, and then 1.00 to 1 between the metal rolls.
．． It is preferable to carry out Nikan rendering treatment so that the weight becomes 20 g/d.

The base paper used for the photographic paper support of the present invention is subjected to the above-mentioned calendering process to give a final grain size of 50 to 250 pm.
is adjusted to

The photographic paper support of the present invention is produced by coating both sides of the base paper with polyolefin.

Examples of the polyolefin resin include homopolymers of α-olefins such as polyethylene and polypropylene, and mixtures of these various polymers. Particularly preferred polyolefins are high density polyethylene, low density polyethylene and mixtures thereof. There is no particular restriction on the molecular weight of these polyolefins as long as they can be extrusion coated, but polyolefins having a molecular weight in the range of 20,000 to 200,000 are usually used.

The thickness of the polyolefin resin coating layer is not particularly limited and can be determined according to the thickness of the polyolefin resin coating layer for conventional photographic paper supports, but is usually 15 to 5.
0 μm is suitable.

Known additives such as white pigments, colored pigments, fluorescent whitening agents, and antioxidants can be added to the polyolefin resin layer. In particular, it is preferable to add a white pigment and a colored pigment to the polyolefin resin coating layer on the surface to which the photographic emulsion is applied.

Incidentally, as the extrusion coating equipment for extrusion coating polyolefin, a usual polyolefin extruder and laminator are used.

The support for photographic Inzai paper of the present invention is further coated with a photographic emulsion layer on one side and dried to obtain a photographic photographic paper. Various aspects are possible, such as being able to provide a.

(Effects of the Invention) According to the present invention, irregularities of various sizes on the surface of the base paper used as a support for photographic printing paper are removed and the surface of the base paper is made sufficiently smooth. A support for photographic paper with excellent smoothness can be easily obtained even if coated with a thin layer of polyolefin, and the support for photographic paper obtained is smooth without blacking or paper bulges. There is no cost problem and it is suitable for glossy photographic paper.

(Examples) Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited by these Examples.

Example 1 A wood valve consisting of 25 parts of LBSP and 75 parts of LBKP was refined to 280 cc of Canadian freeness using a disc refiner, and epoxidized behenic acid amine F0
．． 8 parts, anionic polyacrylamide 1.0 part, cationic polyacrylamide 0.5 part, aluminum sulfate 1.
0 parts and polyamide polyamine epichlorohydrin 0.
After adding 3 parts in the absolute dry weight ratio to the wood pulp, the stock pH was adjusted to 6.8 with caustic soda,
The paper was made using a Fourdrinier paper machine. Carboxy-modified PVA was deposited at an absolute dry weight of 1.0 g/xn'' in the middle of the drying process using a size press device, resulting in a final basis weight of 180 g/m.
” was prepared.

As for the calendering conditions, first, a soft calender (a polyether resin roll with a Shore hardness of 92 and a surface temperature of 6
After setting the density of the base paper to 0.87 g/cd using a metal roll (surface temperature: 110°C) and a metal roll (surface temperature: 70°C), the density was reduced to 1.0 using a machine calender (metal roll; surface temperature: 70°C).
Calendar treatment was performed until the concentration reached 5 g/d. The moisture content of the obtained base paper is 8. 0%, internal bonding force is 1.29kg-
It was cm.

Next, polyethylene was extruded and coated using a laminator, and both sides of the base paper were coated with 28 μm of polyethylene, and the surface of the cooling roll of the laminator, which forms the polyethylene layer on the photographic emulsion side, was mirror-finished to obtain a water-resistant glossy support. . The obtained support was coated with ordinary gelatin and silver halide photographic emulsion, exposed and developed, and then the surface smoothness of the photographic paper was visually judged using a five-point evaluation method, and the evaluation was 5, the highest. It was extremely good.

Example 2 A base paper was prepared in the same manner as in Example 1 except that the freeness was changed to 240 cc and the amount of epoxidized behenic acid amide was changed to 0.5 part.

The resulting base paper had an internal bonding strength of 1.51 kg-cm. Polyethylene was then extrusion coated in the same manner as in Example 1, and a silver halide photographic emulsion was applied. The smoothness of the photographic paper after exposure and development was 5, which was the same as in Example 1, and was extremely good.

Example 3゜The valve used in Example 2 was mixed with 70 parts of LBKP and NBSP.
A base paper was prepared in the same manner as in Example 2 except that the amount was changed to 30 copies. The internal bonding strength of the obtained base paper was 1.15 kg-cm.

The smoothness of the obtained Inzai paper was evaluated in the same manner as in Example 2, and was 4, which was not as good as in Example 2, but was at a good level.

Comparative Example 1゜Same as Example 1 except that the freeness in Example 1 was changed to 380 cc, the amount of epoxidized behenic acid amide added was changed to 1.0 parts, and the amount of anionic polyacrylamide added was changed to 0.5 parts. A base paper was prepared.

When the flatness of the photographic paper was measured in the same manner as in Example 1, it was found that the flatness of the photographic paper was not worth evaluating due to blistering failure that occurred during lamination of polyethylene.

Comparative Example 2゜The pulp used in Example 2 was mixed with 60 parts of LBKP and NBKP.
A base paper was prepared in exactly the same manner as in Example 1, except that the amount of anionic polyacrylamide was changed to 1.2 parts.

The internal bonding strength of the obtained base paper was 1.92 kg-cm, and the flatness of the photographic paper evaluated in the same manner as in Example 2 was only 3.

Comparative Example 3゜Using the paper stock used in Comparative Example 2, the density of the base paper was 1.0 with only machine calendering without soft calender treatment.
Calendering was performed until the concentration reached 5 g/d. The internal bonding strength of the obtained base paper was 1°93 kg-cm, and when the flatness of the obtained photographic paper was evaluated in the same manner as in Example 2, the flatness of the photographic paper was poor at 2, and the commercial value was low. It was something that didn't exist.

Table 1 summarizes the results of Examples 1 to 3 and Comparative Examples 1 to 3.

The results in Table 1 demonstrate that the smoothness of the photographic paper using the photographic paper-like support obtained according to the present invention is extremely good.

Claims (1)

[Scope of Claims] 1) A support for photographic paper in which both sides of a base paper are coated with polyolefin, wherein the base paper has an internal bonding strength of 1.
A support for photographic paper, which has a weight of 2 to 1.8 kg·cm and is a base paper calendered between a metal roll and a synthetic resin roll. 2) The support for photographic paper according to claim 1, wherein the material of the synthetic resin roll used for calendering is a polyether resin. 3) Moisture content of base paper during calendering is 6.0% to 9.0%
%, and the surface temperature of the synthetic resin roll is from 50°C to 250°C.