JPH04342250A - Base for photosensitive material - Google Patents

Abstract

PURPOSE:To provide the base for photosensitive materials formed by coating base paper essentially consisting of natural pulp drastically suppressed in the tendency to the generation of dot troubles in silver halide photosensitive layers with a resin having film formability. CONSTITUTION:A part or the whole of the natural pulp constituting the base paper for photosensitive materials formed by coating the base paper essentially consisting of the natural pulp with the resin having the film formability is natural kraft pulp. This natural kraft pulp is subjected to a washing treatment in the presence of a defoaming agent or foam suppressing agent in the unbleaching stage after digesting by a kraft method and is subjected to an oxygen delignification treatment before and after the washing treatment then to a bleaching treatment in the subsequent bleaching stage. The number of the generation of discoloration by the silver discoloration reaction of the natural kraft pulp is <=20 pieces per A-4.

Description

Detailed Description of the Invention [0001] [Industrial Application Field] The present invention provides a paper base (hereinafter referred to as base paper) mainly composed of natural pulp coated with a resin capable of forming a film, preferably a polyolefin resin. The present invention relates to a support for a resin-coated paper-type photosensitive material, and more particularly to a support for a resin-coated paper-type photosensitive material that has good photographic suitability for a silver halide photosensitive layer. 2. Description of the Related Art Resin-coated paper-type supports for photosensitive materials, in which at least one surface of the substrate is coated with a film-forming resin, are well known as supports for photosensitive materials. For example, Japanese Patent Publication No. 55-12584 discloses a technique for a support for photosensitive materials in which a base paper is coated with a resin capable of forming a film, preferably a polyolefin resin. US Pat. No. 3,501,298 discloses a technique for a support for photosensitive materials in which both sides of a base paper are coated with a polyolefin resin. Furthermore, ever since rapid photographic processing methods for silver halide photographic light-sensitive materials were applied, supports for light-sensitive materials, in which both sides of the base paper are coated with polyethylene resin, have been mainly used for photographic paper. If necessary, the resin layer on one of the image forming sides usually contains a titanium dioxide pigment in order to impart sharpness. However, resin-coated paper-type supports for photosensitive materials, in which a base paper containing natural pulp as a main component is coated with a resin capable of forming a film, still have some serious problems in terms of photographic suitability for silver halide photosensitive layers. It had some problems. That is, when a silver halide photosensitive material having a resin-coated paper as a support, which is a base paper mainly composed of natural pulp coated with a film-forming resin, is stored after its manufacture.
When stored for a long period of time, especially when stored under high temperature and high humidity, the silver halide in the photosensitive material may fog up in spots, and the unexposed areas can be developed into spots during the development process. There is a problem in that the sensitivity of the photosensitive material may decrease or increase in spots. For example, in the case of a certain type of positive black and white silver halide photographic paper that uses the resin-coated paper as a support, speckled fog appears on the white background. This speckled fog can sometimes reach a diameter of more than 20 mm, rendering the photographic paper completely worthless as a commercial product. In addition, in the case of a type of photosensitive material using the silver salt diffusion transfer method that has the resin-coated paper as a support for the silver halide negative photosensitive layer, spotty fogging occurs on the negative side silver halide photosensitive layer. As a result, the image density on the positive side decreases in spots, and the silver image is hardly formed in spots, resulting in no commercial value at all. In addition, in the case of a certain type of multilayer silver halide color photographic paper in which the resin-coated paper is used as a support and a yellow coloring layer, a magenta coloring layer, and a cyan coloring layer are sequentially arranged adjacent to the support, a speckled color is formed. In addition to fogging, the sensitivity of the yellow and magenta coloring layers in particular decreases in spots, and the color balance of the image deteriorates in spots, resulting in a loss of commercial value of the photographic paper. Hereinafter, these phenomena will be collectively referred to as spot failures. Up to now, various stabilizers or fog suppressants have been proposed for preventing changes in photographic properties of silver halide photosensitive materials during storage. However, even if various stabilizers or fog suppressants are contained in the constituent layers of a silver halide photosensitive material using resin-coated paper as a support, considerable photographic adverse effects such as a decrease in sensitivity and a softening of tone may occur. In addition to this, it was almost impossible to prevent spotty failures. There are also several proposals regarding the photographic properties of supports for light-sensitive materials. Japanese Patent Publication No. 54-9844 proposes an anti-fogging, resin-coated paper-type support for photosensitive materials in which a base paper is coated with a polyolefin resin containing a hydroxy-substituted-triazolopyrimidine compound. It was extremely insufficient to prevent spot failures in silver halide light-sensitive materials having the support. Regarding photographic paper, Japanese Patent Laid-Open No. 52-65423 and Japanese Patent Publication No. 58-43730 propose eliminating the adverse effects on photographic properties due to the decomposition of cationic electrolytes and additive chemicals for paper, respectively. In silver halide photosensitive materials that use resin-coated photographic paper as a support, spot failures cannot be prevented at all, and spot failures occur due to a mechanism completely different from that described in these specifications. It became clear that it would. Also, JP-A-2-9674
No. 1, JP-A No. 2-99689 and JP-A No. 2-99
No. 693 proposes a technique for improving the photographic properties of unbleached kraft paper. According to them, bleached kraft paper has good photographic properties, but unbleached kraft paper has poor photographic properties.
The cause of this is that propylene oxide and/or silicone, which are antifoaming components used in the unbleached stage, remain. By specifying the antifoaming agent containing these components and the cold water extraction pH, unbleached kraft paper It has been proposed to improve the photographic properties of. However, in the case of silver halide photosensitive materials using resin-coated paper as a support made of base paper mainly composed of bleached natural pulp to which this technology is applied, spot failures cannot be prevented at all; It has become clear that this phenomenon is caused by a completely different mechanism than that described in the book. Furthermore, Special Public Interest Publication No. 58-43732
No. 1, a technique was proposed to improve the shelf life of silver halide photographic materials by using a resin-coated paper consisting of a base paper based on natural pulp bleached with alkaline peroxide. Even when the resin-coated paper was used, it was insufficient to prevent spot failures. Furthermore, the special public
No. 9-38575 proposes a technique for preventing fog and spots in silver halide photographic materials by using photographic paper using wood pulp obtained by oxygen pulping method, but it is not possible to use this photographic paper as a substrate. Even with resin-coated paper, prevention of spot failure remained insufficient. As described above, techniques for improving spot failures in silver halide photosensitive materials using resin-coated paper as a support, in which a base paper containing natural pulp as a main component is coated with a resin capable of forming a film, and techniques for improving spot failures have been described. The mechanism or cause of occurrence is
This is completely unknown, and it has not been possible to improve the spot failure using conventionally known techniques. SUMMARY OF THE INVENTION Therefore, it is an object of the present invention to provide a base paper containing natural pulp as a main component, in which the tendency of spot failure to occur in a silver halide photosensitive layer is significantly suppressed. An object of the present invention is to provide a support for a photosensitive material coated with a resin capable of forming a film. Other objects of the invention will become apparent from the description below. Means and Effects for Solving the Problems In order to solve the above-mentioned problems, the inventors of the present invention, as a result of intensive studies, developed a base paper mainly composed of natural pulp with a film-forming resin. In the coated support for photosensitive materials, part or all of the natural pulp constituting the base paper is natural kraft pulp, and as the natural kraft pulp, an antifoaming agent or foam suppressor is added to the natural kraft pulp in the unbleached stage after cooking by the kraft method. washed in the presence of a cleaning agent, subjected to oxygen delignification treatment before and after the washing treatment, and bleached in the subsequent bleaching step,
Furthermore, it has been found that the object of the present invention can be achieved by using natural kraft pulp in which the number of discolorations due to the silver discoloration reaction defined herein is 20 or less per A-4. did. In this specification, the number of discolored particles due to silver discoloration reaction refers to a natural kraft pulp sample on the silver surface of a silver plate prepared based on Tappi Standard T444 (sample conditions include basis weight;
50g/m2±150g/m2, absolute dry moisture content; 20% by weight±5% by weight, pH; Tappi Standard T20
The pH of the pulp suspension when prepared based on 5) is 6.0 to 7.5), sealed in a black plastic bag, and a load of 2.5 kg per A-4 is applied. , temperature 50℃
A heating treatment was performed for 50 hours under conditions of ±1° C. and relative humidity of 81% ±2%, and then the number of silver discoloration reactions occurring on the silver surface was counted. According to the studies conducted by the present inventors, when natural kraft pulp is washed in the presence of an antifoaming agent or a foam suppressing agent in the unbleached stage after cooking, it has been found that the presence of black liquor components or black liquor modifying components Water-insoluble or poorly water-soluble silver discoloration reaction generating substances are occluded by the action of antifoaming agents or foam suppressing agents,
Surprisingly, the silver discoloration reaction product remains in the bleached natural kraft pulp even after being attacked by oxidizing agents or alkaline agents in the subsequent bleaching step.
Furthermore, it was found that the bleached natural kraft pulp remained locally on the base paper after beating and papermaking, and that the silver discoloration reaction-generating substance caused spot failures, and furthermore, it was found that the unbleached stage of the bleached natural kraft pulp after cooking by the kraft method caused spot failure. The material is washed in the presence of an antifoaming agent or foam suppressant, and is subjected to oxygen delignification treatment before and after the washing treatment, and bleached in the subsequent bleaching step, and contains fewer substances that generate silver discoloration reactions. It was discovered that spot failure could be improved by using natural kraft pulp, leading to the present invention. As the natural kraft pulp used in the practice of the present invention, wood kraft pulps such as softwood kraft pulp, hardwood kraft pulp, and mixed kraft pulp of softwood and hardwood are advantageously used. These wood craft pulps are made by removing lignin from wood chips by pressure cooking, or cooking, in a mixture containing sodium hydroxide and sodium sulfide as chemical components, known as cooking liquor.
Thereafter, the pulp fibers and the cooking residue, so-called black liquor, are separated and washed in the presence of an antifoaming agent or a foam suppressing agent, and then subjected to an oxygen delignification treatment, and then a bleaching treatment. In addition to sodium hydroxide and sodium sulfide, the chemical components in the cooking liquor include salts such as sodium carbonate, sodium sulfate, slaked lime, and calcium carbonate, and cooking aids such as sodium borohydride and anthraquinone compounds. You can. Further, it may be produced by various cooking methods such as polysulfide cooking, batch cooking, continuous cooking, etc., and may be produced with various sulfidity degrees and kappa numbers. [0012] The base paper used in the practice of the present invention has natural pulp as its main component, and part or all of it is composed of natural kraft pulp, preferably wood kraft pulp, but it can also be used in combination with natural kraft pulp. If necessary, it may be made of natural pulp other than natural kraft pulp, synthetic fiber, or synthetic pulp. As the pulp used in combination with natural kraft pulp, natural pulp is preferred, and wood sulfite pulp such as softwood sulfite pulp, hardwood sulfite pulp, and softwood hardwood mixed sulfite pulp is particularly preferred. Further, wood soda pulp, wood dissolving pulp, etc. can also be used. Various antifoaming agents or antifoaming agents can be used in the practice of the present invention. For example, JP-A-54-59404, JP-A-58-220896, JP-A-61-245391, JP-A-61-245.
319, U.S. Patent No. 3,923,638, U.S. Patent No. 4,107,073, etc., containing higher fatty acid alcohol ester compounds, mineral oil or liquid hydrocarbon oil, silicone oil, etc. as components. can be used. Among these, water-based or oil-based antifoaming agents or antifoaming agents containing mineral oil or liquid hydrocarbon oil as a component are particularly preferred from the viewpoint of antifoaming or antifoaming properties. In addition, the antifoaming agent or the foam suppressing agent includes:
It may contain components such as hydrophobic silica, ethylenebishigher alkylamide, and silicone oil. A method for making these defoamers or foam inhibitors present during the cleaning process of unbleached kraft pulp is to add the defoamer or foam inhibitor to the unbleached kraft pulp slurry or thickener at any stage during the cleaning process. It is preferable to add [0014] The natural kraft pulp, preferably wood kraft pulp, used in the practice of the present invention is prepared by washing after cooking, followed by oxygen delignification, preferably further washing, and then bleaching. something can be used to advantage. The treatment conditions for oxygen delignification include a degree of delignification at the oxygen delignification stage of 20 to
It is preferable to set it to 70%, preferably 40 to 50%. Further, the oxygen delignification treatment is carried out in the presence of at least oxygen and an alkali, preferably also an agent for inhibiting a decrease in the degree of polymerization of the pulp. The oxygen used for oxygen delignification treatment is supplied from an oxygen cylinder,
A material whose main component is oxygen produced from air using an oxygen enrichment membrane is advantageously used. Further, in the oxygen delignification treatment, oxygen may be used alone, or an oxygen-based oxidizing agent such as hydrogen peroxide may be used in combination, ozone, nitrogen oxide, etc. may be used. The alkalis used in oxygen delignification treatment include:
Although alkaline liquids such as sodium hydroxide, sodium carbonate, oxidized white liquor, and oxidized green liquor can be used, it is preferable to use oxygenated white liquor. In addition, examples of the pulp polymerization degree reduction inhibitor preferably used in the oxygen delignification treatment include magnesium carbonate, magnesium sulfate, calcium chloride, and the like. As specific conditions for the oxygen delignification treatment, various treatment conditions can be used. for example,
Specifically, the pulp concentration is in the range of 5 wt% to 35 wt%, preferably 10 wt% as the bone dry weight of unbleached pulp.
The amount of oxygen added is in the range of wt% to 20 wt%, and the amount of alkali added is in the range of 0.2 wt% to 4 wt%, preferably 0.5 wt% to 2 wt%, based on the bone dry weight of unbleached pulp. is in the range of 0.2 wt% to 7 wt% in terms of caustic soda per bone dry weight of unbleached pulp, preferably 0.
．． It is in the range of 5wt% to 3wt%. Moreover, the treatment temperature of the oxygen delignification treatment is preferably in the range of 50° C. to 150° C., and the treatment time is preferably in the range of 10 minutes to 180 minutes. In addition, the amount of the pulp polymerization degree reduction inhibitor used as necessary is 0 per absolute dry weight of unbleached pulp.
．． The range is preferably from 0.05 wt% to 1 wt%. The natural kraft pulp, preferably wood kraft pulp, used in the practice of the present invention is one that has been subjected to a bleaching process during its cooking, washing, oxygen delignification, and post-washing bleaching steps. As the bleaching treatment, chlorine treatment, alkali treatment or extraction or purification, hypochlorite bleaching treatment, chlorine dioxide bleaching treatment, and a combination thereof multistage bleaching treatment are preferable, and if necessary, Japanese Patent Publication No. 58
The alkaline peroxide bleaching treatment described or exemplified in No. 43732, or the reductive bleaching treatment using hydrosulfite, sodium borohydride, etc. may be performed. In addition, the bleaching stage mentioned in this specification is the bleaching stage after the chlorination stage. [0016] A preferred multi-stage bleaching treatment system for wood kraft pulp that is advantageously used in the practice of the present invention includes a chlorination stage (hereinafter abbreviated as C) in the first stage and an alkali treatment or extraction stage (hereinafter referred to as C) in the second stage. The third stage is a hypochlorite bleaching stage (hereinafter abbreviated as symbol H) or a chlorine dioxide bleaching stage (hereinafter abbreviated as symbol D). Oxide bleaching stage (
(hereinafter abbreviated as P) is advantageously carried out in the fourth stage or later. For example, "CEHDED", "CEH
DPD”, “CEHDEDP”, “CEHED”, “C
EHPD”, “CEHEDP”, “CEHEH”, “C
EHEHP”, “CEHPHP”, “CEDED”, “
A method such as "CEDEDP" is useful. Chlorine gas or chlorine water is used for chlorine bleaching as the wood kraft pulp bleaching chemical that is advantageously used in the practice of the present invention. Additionally, chlorine dioxide may be used in combination. Caustic soda is advantageously used for the alkaline treatment or extraction, but calcium hydroxide, ammonia, etc. and mixtures thereof can also be used. Hypochlorite bleaching involves bleaching powder made by treating solid powdered slaked lime with chlorine, and especially industrially, hypochlorous acid bleaching solution prepared by blowing chlorine into milk of lime or dilute caustic soda solution. , so-called calcium-hypo bleaching solution, sodium-
A hypo bleaching solution is advantageously used. For chlorine dioxide bleaching,
Mattison method, new Mattison method, Elst method, C. I. Chlorine dioxide prepared by a sulfite method such as the P method, a hydrochloric acid method such as the Kesting method, the Nisso method, or the Solvay method is advantageously used. For alkaline peroxide bleaching, peroxides such as hydrogen peroxide, sodium peroxide, peroxide bleaching solution (hydrogen peroxide, caustic soda, silicate soda, and Advantageously, inorganic or organic peroxides and mixtures thereof are used, such as peracetic acid, tert-butyl hydroperoxide (mixed aqueous solutions consisting of added magnesium sulfate), peracetic acid, tert-butyl hydroperoxide, and as alkalis, caustic soda, potassium hydroxide, Alkali or alkaline earth hydroxides such as aqueous ammonia, magnesium hydroxide, calcium hydroxide and mixtures thereof are advantageously used. Also,
The bleaching treatment can be carried out under various conditions, such as those described in "Pulp Treatment and Bleaching" edited by the Paper and Pulp Technology Association (published on January 27, 1961), Japanese Patent Publication No. 43732/1983. The natural kraft pulp, preferably wood kraft pulp, used in the practice of the present invention has a discoloration count of A-4 due to a silver discoloration reaction as defined herein.
20 or less pieces per A-4, preferably 10 or less pieces per A-4, more preferably 5 or less pieces per A-4, and 2 or less pieces (including 0 pieces) per A-4. is most preferred. Natural kraft pulp, preferably wood kraft pulp, in which the number of discolorations due to silver discoloration reaction is 20 or less per A-4, is specifically treated with oxygen delignification and, for example, by using the following method, Studies by the present inventors have revealed that it can be obtained preferably by using two or more of the following methods, more preferably in combination of three or more. (1) The amount of antifoaming agent to be used is expressed as its components (components excluding water in the case of an aqueous-based antifoaming agent) per unbleached pulp (hereinafter, absolute dry weight unless otherwise specified). ) 0.1-1.5kg, preferably 0.1-1.0k
g, more preferably in the range of 0.1 to 0.75 kg. (2) The pH of the unbleached kraft pulp thickener before entering the bleaching stage is 6.0 or higher, preferably 6.5.
Above, more preferably 7.0 or above. In addition, the pH of unbleached kraft pulp thickener means that 300 g of distilled water is added to 50 g of unbleached kraft pulp thickener, and after stirring well for 1 hour, the liquid temperature is adjusted to 25°C ± 25°C using a pH meter.
Measured at 1°C. (3) The electrical conductivity of the unbleached kraft pulp thickener before entering the bleaching step is adjusted to be at least 50 μmho/cm, preferably at least 100 μmho/cm, and more preferably at least 150 μmho/cm. In addition,
The electrical conductivity of unbleached kraft pulp thickener is as follows: Add 300 g of distilled water to 50 g of unbleached kraft pulp thickener, stir well for 1 hour, and then measure the liquid temperature at 25°C using an electrical conductivity meter.
Measured at ±1°C. (4) The calcium content in the unbleached kraft pulp before entering the bleaching stage is minimized. Specifically, when paper is made of unbleached kraft pulp thickener before entering the bleaching stage, the calcium content in the paper is reduced to 50%.
00 ppm or less, preferably 4000 ppm or less, more preferably 3000 ppm or less. The paper was prepared using unbleached kraft pulp thickener in accordance with Tappi Standard T-205, except that deionized water was used. It was measured using the X-ray method. (5) The calcium content in unbleached white water should be as low as possible. To this end, the calcium content derived from the cooking process is reduced. For example, selecting an appropriate tree species, improving the removal efficiency of insoluble calcium salts present in white water, such as calcium hydroxide and calcium carbonate, by filtration, and adding chelating agents, such as EDTA-sodium salt, to unbleached white water. It is preferable to add . (6) The pH of the kraft pulp slurry in the chlorine stage is 2.5 or less, preferably 2.5 or less.
The value should be 0 or less, more preferably 1.5 or less. (7) Before entering the papermaking process, the bleached kraft pulp is cleaned using a cleaner, preferably a liquid cyclone type cleaner. The final rejection rate in the cleaner is preferably 0.02% by weight or more, preferably 0.05% by weight or more, and more preferably 0.1% by weight or more, based on the bone dry pulp. [0026] The base paper used in the practice of the present invention can contain various additives at the time of preparing the paper stock slurry. Sizing agents include fatty acid metal salts and/or fatty acids, alkyl ketene dimer emulsions or epoxidized higher fatty acid amides as described or exemplified in Japanese Patent Publication No. 62-7534, alkenyl or alkyl succinic anhydride emulsions, rosin derivatives, etc. As a paper strength enhancer,
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.; water-soluble aluminum salts such as aluminum chloride, aluminum sulfate, etc. as fixing agents; caustic soda, soda carbonate, sulfuric acid, etc. as pH regulators; and others JP-A-63-204251
It is advantageous to contain a suitable combination of coloring pigments, coloring dyes, fluorescent brighteners, etc. described or exemplified in JP-A-1-266537 and the like. [0027] Furthermore, various water-soluble polymers, antistatic agents, and additives can be added to the base paper used in the practice of the present invention by spraying or tab size press. As a water-soluble polymer, JP-A-1-266
Starch polymers, polyvinyl alcohol polymers, gelatin polymers, polyacrylamide polymers, cellulose polymers, etc. described or exemplified in No. Alkaline earth metal salts such as barium, colloidal metal oxides such as colloidal silica, organic antistatic agents such as polystyrene sulfonates, latexes, emulsions, petroleum resin emulsions, styrene-acrylic acid-acrylic acid esters, etc. Latex such as copolymers, styrene-acrylic acid-butadiene copolymers, ethylene-vinyl acetate copolymers, styrene-maleic acid-acrylic acid ester copolymers, pigments such as clay, kaolin, talc, barium sulfate, oxidation It is advantageous to contain a pH adjusting agent such as titanium, hydrochloric acid, phosphoric acid, citric acid, caustic soda, etc., as well as an appropriate combination of additives such as the above-mentioned colored pigments, colored dyes, and optical brighteners. [0028] The base paper used in carrying out the present invention is as follows:
It is preferable to have a smooth surface with a Beck smoothness of 100 seconds or more as defined by JIS P8119, and 200 seconds or more.
It is even more preferable to have a smooth surface with a smoothness of at least 2 seconds. As a method for producing a base paper with a Bekk smoothness of 100 seconds or more, generally a large amount of hardwood pulp, which has short fibers and is easily smooth, is used, and the pulp is beaten using a beating machine to reduce the long fiber content as much as possible. Specifically, the pulp is preferably beaten so that the fiber length of the pulp after beating is such that the 42 mesh residue is 20 to 45% and the freeness is 200 to 350 CSF. Next, regarding paper stock chillers with internal additives added, JP-A No. 58-37642 and JP-A No. 61-260240
A uniform texture can be obtained using a commonly used paper machine such as a fourdrinier paper machine or a circular paper machine by adopting an appropriate paper making method as described or exemplified in JP-A No. 61-284762. A base paper having a Bekk smoothness of 100 seconds or more can be produced by papermaking as described above, and then calendering using a machine calender, a supercalender, a thermal calender, etc. after the papermaking. There are no particular restrictions on the thickness of the base paper, but its basis weight is 40 g/m2 to 250 g/m
2 is preferred. As the film-forming resin used in the practice of the present invention, thermoplastic resins such as polyolefin resins, polycarbonate resins, polyester resins, and polyamide resins are preferable, and among them, thermoplastic resins are preferable in terms of melt extrusion coating properties. More preferred are polyolefin resins. Also,
It may be coated with an electron beam curing resin described or exemplified in Japanese Patent Publication No. 60-17104. Polyolefin resins preferably used in the practice of the present invention include homopolymers such as polyethylene, polypropylene, polybutene, and polypentene, copolymers consisting of two or more α-olefins such as ethylene-butylene copolymers, and copolymers of these. Among them, polyethylene resin is particularly preferred from the viewpoint of melt extrusion coating properties and adhesion to the base paper. These polyethylene resins include low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, copolymers of ethylene and α-olefins such as propylene and butylene, carboxy-modified polyethylene, etc. It is a mixture and can have various densities, melt flow rates (hereinafter simply referred to as MFR), molecular weights, and molecular weight distributions, but usually has a density of 0.90 to 0.97 g/
cm3 range, MFR0.1g/10min~40g/1
0 minutes, preferably MFR0.3g/10 minutes to 30g/
10 minutes, those having a molecular weight in the range of 20,000 to 250,000 can be advantageously used alone or in combination. In addition, if the resin has a multilayer structure, the outermost layer resin may have a MFR of 5g/10, for example.
It is also possible to use resins with different properties and configurations, such as those with MFR of 2 g/10 minutes to 10 g/10 minutes, as the lower layer resin. [0031] Various additives can be contained in the resin layer of the support for photosensitive materials in the present invention. Special Publication No. 60-3430, Special Publication No. 63-11655,
White pigments such as titanium oxide, zinc oxide, talc, calcium carbonate, etc., stearic acid amide, arachidic acid amide, etc. described or exemplified in Japanese Patent Publication No. 1-38291, Japanese Patent Publication No. 1-38292, and Japanese Patent Publication No. 1-105245, etc. Fatty acid metal salts such as fatty acid amide, zinc stearate, calcium stearate, aluminum stearate, magnesium stearate, zinc palmitate, zinc myristate, calcium palmitate, etc., JP-A-1-1052
Various antioxidants such as hindered phenol, hindered amine, phosphorus type, and sulfur type antioxidants described or exemplified in No. 45,
Blue pigments and dyes such as cobalt blue, ultramarine blue, ceriam blue, and phthalocyanine blue; magenta pigments and dyes such as cobalt violet, fast violet, and manganese violet; Various additives such as fluorescent brighteners and ultraviolet absorbers can be contained in appropriate combinations. Preferably, these additives are included as a masterbatch or compound of a film-forming resin. In addition, when the film-forming resin is a thermoplastic resin, preferably a polyethylene resin, the resin layer is preferably manufactured by a melt extrusion coating method in which the molten resin is coated on a running base paper. . Before coating the base paper with the resin, it is preferable to subject the base paper to an activation treatment such as a corona discharge treatment or a flame treatment. In the present invention, the surface of the photosensitive layer side of the support for a photosensitive material is a glossy surface or a surface of Japanese Patent Publication No. 62-197 which does not affect the gloss of the surface of the photosensitive material when it is made into a photosensitive material.
It has a finely rough surface, matte surface, silky surface, etc. as described in No. 32, and the back surface is usually a matte surface, and if necessary, the front surface or both the front and back surfaces can be subjected to activation treatment such as corona discharge treatment or flame treatment. can be administered. Further, after the activation process, a subbing process as described in JP-A-61-84643 can be performed. Further, there is no particular restriction on the thickness of the front and back resin layers, but it is generally advantageous to have a thickness of about 10 .mu.m to 50 .mu.m. [0033] The support for the photosensitive material in the present invention can be coated with various back coat layers for antistatic purposes, anti-curling, and the like. In addition, for the back coat layer, Japanese Patent Publication No. 52-18020, Japanese Patent Publication No. 57-9059,
JP 57-53940, JP 58-56859, JP 59-214849, JP 58-184
Inorganic antistatic agents, organic antistatic agents, hydrophilic binders, latexes, curing agents, pigments, surfactants, etc. described or exemplified in No. 144 and the like may be contained in appropriate combinations. The support for photosensitive materials in the present invention is coated with various photographic constituent layers and can be used for color photographic paper, black and white photographic paper, typesetting photographic paper, copying photographic paper, and reversal photographic material. It can be used for various purposes such as silver salt diffusion transfer negatives and printing materials. For example, silver chloride, silver bromide, silver chlorobromide, silver iodobromide, and silver chloroiodobromide emulsion layers can be provided. A multilayer silver halide color photographic constituent layer can be provided by incorporating a color coupler in the silver halide photographic emulsion layer. Further, a photosensitive layer for silver salt diffusion transfer method can be provided. As the binder for these photographic constituent 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 photographic constituent 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, and antifoggants or stabilizers include hydroxy-triazolopyrimidine compounds and mercapto-heterocyclic compounds. Hardeners include formalin, vinyl sulfone compounds, aziridine compounds, etc. Coating aids include alkylbenzene sulfonates, sulfosuccinates, etc. Anti-staining agents include dialkylhydroquinone compounds, and other optical brighteners and sharpness improvers. A dye, an antistatic agent, a pH adjuster, a fogging agent, and further a water-soluble iridium, a water-soluble rhodium compound, etc. can be contained in an appropriate combination during the production and dispersion of silver halide. The photosensitive material of the present invention can be exposed to light as described in ``Photographic Photosensitive Materials and Handling Methods'' (Kyoritsu Shuppan, written by Goro Miyamoto, Photographic Technology Course 2), depending on the photosensitive material.
Processes such as development, stopping, fixing, bleaching, and stabilization are carried out, and multilayer silver halide color photographic light-sensitive materials that undergo one-bath bleach-fixing treatment after color development are CD-III and CD-IV.
Processing can be carried out with any color developer containing any main ingredient, such as (the above two compounds are trade names of Kodak Co.) and droxychrome (trade name of May and Baker Co.). A developer containing such a main agent may contain a development accelerator such as benzyl alcohol, thallium salt, or phenidone.
It is also possible to process with a developer substantially free of benzyl alcohol. Also, useful one-bath bleach-fix solutions are solutions of metal salts of aminopolycarboxylic acids (e.g., ferric complex salts such as ethylenediaminetetraacetic acid and propylenediaminetetraacetic acid), and the fixing agent is sodium thiosulfate. , ammonium thiosulfate, and the like are useful. Such a one-bath bleach-fix solution may contain various additives. For example, desilvering accelerators (e.g., U.S. Pat. No. 3,512,97
mercaptocarboxylic acids described in Belgian Patent No. 9, mercapto-heterocyclic compounds described in Belgian Patent No. 682,426, etc.), antifouling agents, pH adjusters or pH buffers,
Various compounds such as hardeners (for example, magnesium sulfate, aluminum sulfate, potassium alum, etc.) and surfactants can be contained in combination. Additionally, such one-bath bleach-fix solutions may be used at a variety of pHs, but at a useful pH.
The range is pH 6.0-8.0. [Example] Next, in order to explain the present invention more specifically,
An example will be described. Example 1 In the manufacturing process of hardwood kraft pulp, the unbleached kraft pulp after cooking was washed in the first stage washing process, and then subjected to oxygen delignification treatment under the following conditions. It was washed in the first washing process, and then bleached using the "CEHDPD" method in the subsequent steps. On the other hand, the oxygen delignification treatment was omitted in the manufacturing process of hardwood pulp for comparison. The conditions for oxygen delignification treatment are:
The pulp concentration was 15 wt% as the bone dry weight of unbleached pulp, the amounts of caustic soda and oxygen added were 1.5 wt% and 1.0 wt%, respectively, based on the bone dry weight of unbleached pulp, and the treatment temperature and treatment time were 110°C and 45 minutes, respectively. Met. Also,
As a process condition other than the oxygen delignification process of hardwood kraft pulp, the total amount of oil-based antifoaming agent containing mineral oil as a component in the washing stage of unbleached kraft pulp is 1 ton of absolute dry weight of unbleached pulp. 0.7kg, 1.0k per
g, 1.5 kg or 2.0 kg, the electrical conductivity of the unbleached thickener as defined in the specification is 100 μmho/cm, and the final rejection rate of the liquid cyclone type cleaner is 0.5 kg compared to bone dry pulp. 01wt%, 0.02wt%
, 0.05 wt% or 0.1 wt%, adjusted to the combinations listed in Table 1, and adjusting other process conditions appropriately, the number of discolored particles due to the silver discoloration reaction defined in the specification is as shown in Table 1. Hardwood bleached kraft pulps were obtained as follows. [0038] Next, each pulp was
Beaten to 320 ml of standard freeness, and further add 3 parts by weight of cationized starch to 100 parts by weight of pulp.
0.2 parts by weight of anionized polyacrylamide, 0.0 parts of alkyl ketene dimer emulsion (as ketene dimer content).
4 parts by weight and 0.4 parts by weight of polyaminopolyamide epichlorohydrin resin were added to produce paper with a basis weight of 100 g/m2. The obtained wet paper paper was dried at 110°C, and then mixed with 3 parts by weight of carboxy-modified polyvinyl alcohol, 0.05 parts by weight of optical brightener, 0.002 parts by weight of blue dye, 0.2 parts by weight of citric acid, and 97 parts by weight of water. An impregnating solution consisting of 25 parts
After impregnating the paper with g/m2, drying with hot air at 110°C, and supercalendering at a linear pressure of 90kg/cm, both sides of the paper were subjected to corona discharge treatment to produce a base paper for a support for a photosensitive material. Next, low density polyethylene resin (density 0.92 g/cm3, MFR=8.5 g/1
0 min) 47.5 wt%, hydrated aluminum oxide (0.75 wt% as Al2O3 min with respect to titanium dioxide)
20 parts by weight of a titanium dioxide pigment masterbatch consisting of 50% by weight of anatase-type titanium dioxide pigment and 2.5% by weight of zinc stearate, which had been surface-treated with a low-density polyethylene resin (density 0.92 g/cm3, MFR=4. 5g
/10 minutes) 65 parts by weight and high density polyethylene resin (density 0.97 g/cm3, MFR = 7.0 g/10 minutes) 1
13 parts by weight of a resin composition at a resin temperature of 330°C.
Melt extrusion coating was performed to a thickness of μ. In addition, before coating the resin layer on the surface of the base paper, the opposite side (back side) of the base paper
, low-density polyethylene resin (density 0.92 g/cm3
, MFR2g/10min) 15 parts by weight and high density polyethylene resin (density 0.96g/cm3, MFR20g/10
) 85 parts by weight of the resin composition at a resin temperature of 330°C.
Melt extrusion coating was applied to the same thickness as the surface. At this time, the surface of the resin layer containing the titanium dioxide pigment of the support for a light-sensitive material produced in this manner was processed to have a slightly rough surface, and the surface quality of the back resin layer was processed to have a paper-like matte surface. Thereafter, a back coat layer having a composition of colloidal silica: styrene acrylic latex = 1:1 was coated at 0.4 g/m 2 on the back surface of the support for photosensitive materials after corona discharge treatment. Next, a corona discharge treated emulsion layer and its protective layer were provided on the front resin surface containing the titanium dioxide pigment of the photosensitive material support to obtain a black and white photographic paper. The emulsion layer is hexachloroiridium(III)
14. gelatin in the presence of 1.2 x 10-5 g of potassium.
ArBr/AgCl = 65/35 produced by producing and dispersing 19.2g of silver halide particles with silver nitrate in 4g
Substantially [1
, 0, 0] plane, and further contains gelatin necessary for film formation, as well as appropriate amounts of stabilizers, sensitizing dyes, coating aids, hardeners, and optical brighteners. , thickener, filter dye, etc., and was coated in a multilayer together with a protective layer at a coating amount corresponding to 2.2 g/m 2 of silver nitrate and 4.4 g/m 2 of gelatin. The protective layer contains gelatin equivalent to 2 g/m 2 as well as coating aids and hardeners. [0041] The coated and dried sample had a temperature of 4 at 50°C and 81%.
After being stored for a day, it was developed in black and white and the number of speckled fogs was counted. The results obtained are shown in Table 1. [Table 1] [0043] As can be seen from Table 1, wood kraft pulp that has been subjected to oxygen delignification treatment and has a discoloration of 20 or less particles per A-4 due to a silver discoloration reaction as defined in the specification is used. The sample of the present invention, which was used as a wood kraft pulp, had less occurrence of spot fog, and the number of discoloration was 1 per A-4 as a wood craft pulp.
It is clear that the number is preferably 0 or less, and more preferably 5 or less per A-4. Example 2 The same procedure as in Example 1 was carried out, except that instead of the wood kraft pulp used in Example 1, one was subjected to oxygen delignification treatment and produced under the following process conditions. carried out. In the manufacturing process of hardwood kraft pulp, as a process condition, the total amount of oil-based antifoaming agent containing mineral oil as a component in the washing stage of unbleached kraft pulp is 0.1 kg per ton of weight, 0
．． 7kg, 1.0kg, 1.5kg or 2.0kg,
The electrical conductivity of unbleached thickener as defined in the specification is 45
μmho/cm, 100μmho/cm or 150μ
mho/cm, and the final rejection rate of the liquid cyclone type cleaner is 0.01 wt% with respect to bone dry pulp,
0.02 wt%, 0.05 wt%, or 0.1 wt%, adjusted to the combinations listed in Table 2, and other process conditions appropriately adjusted to cause discoloration due to the silver discoloration reaction defined in the specification. Hardwood bleached pulps having the numbers shown in Table 2 were obtained. Note that the amount of antifoaming agent present is 0.
When the weight was less than 1 kg, foaming was insufficiently prevented. The results obtained are shown in Table 2. [Table 2] [0048] As can be seen from Table 2, wood kraft pulp that has been subjected to oxygen delignification treatment and has a discoloration of 20 or less particles per A-4 due to a silver discoloration reaction as defined in the specification is used. The sample of the present invention, which was used as a wood kraft pulp, had less occurrence of spot fog, and the number of discoloration was 1 per A-4 as a wood craft pulp.
It is clear that the number is preferably 0 or less, and more preferably 5 or less per A-4. Example 3 The same procedure as in Example 1 was carried out, except that instead of the wood kraft pulp used in Example 1, one was subjected to oxygen delignification treatment and produced under the following process conditions. carried out. In the manufacturing process of hardwood kraft pulp, as a process condition, the total amount of oil-based antifoaming agent containing mineral oil as a component in the washing stage of unbleached kraft pulp is 0.1 kg per ton of weight, 0
．． 7kg, 1.0kg, 1.5kg or 2.0kg,
Calcium content in unbleached kraft pulp as defined in the specification is 3000 ppm, 4000 ppm, or 5
500 ppm, and the pH of the kraft pulp slurry at the chlorine stage is pH 1.5, pH 2.0 or pH 2.7.
By adjusting the combinations shown in Table 3 and adjusting other process conditions as appropriate, hardwood bleached pulps having the number of discolored particles due to the silver discoloration reaction defined in the specification as shown in Table 3 were obtained. Ta. The results obtained are shown in Table 3. [Table 3] [0053] As can be seen from Table 3, wood kraft pulp that has been subjected to oxygen delignification treatment and has a discoloration of 20 or less pieces per A-4 due to a silver discoloration reaction as defined in the specification is used. It can be clearly seen that the samples of the present invention, which were used as wood kraft pulps, have little occurrence of spotty fog, and as a wood craft pulp, the number of discolored particles is preferably 10 or less per A-4, and more preferably 5 or less per A-4. Example 4 The number of discolorations caused by the silver discoloration reaction used in Example 2 was A-
The procedure was the same as in Example 1, except that wood kraft pulp with 2.25 pieces and 28 pieces per 4 pieces was used, the basis weight of the base paper was 160 g/m2, and the thickness of the front and back resin layers were each 30 μm. A support for a photosensitive material was obtained. Next, the resin surface on the front side containing the titanium dioxide pigment of the support for a light-sensitive material was subjected to a corona discharge treatment, and then the following emulsion layer and its protective layer were provided to obtain a photographic paper. The emulsion layer is potassium hexachloroiridium(III) 1.0×10-5
In the presence of 9.6 g of silver nitrate in 4.8 g of gelatin
AgB produced by producing and dispersing silver halide grains
Sulfur-sensitized to the highest sensitivity with an average particle size of 0.8μ and a halogen composition of r/AgCl = 95/5 [1, 0, 0
Contains a neutral silver halide photographic emulsion consisting of a mixed crystal of ] and [1,1,1] planes, and further contains a yellow color-forming coupler and gelatin necessary for film formation, as well as an appropriate amount of stabilizers and blue sensitivity. Contains sensitizing dyes, coating aids, hardeners, thickeners, etc., and contains 0 silver nitrate.
．． A multilayer coating was carried out together with a protective layer at a coating weight of 6 g/m2, which corresponds to 1.5 g/m2 of gelatin. The protective layer is 1.5
In addition to gelatin equivalent to g/m2, coating aids, thickeners,
Contains hardening agents, etc. [0056] The coated and dried sample had a temperature of 4 at 50°C and 81%.
After storage for a day, color development was performed and the number of speckled fogs was counted. In addition, the sample after heating and storage was uniformly exposed to light so that the yellow color density was 0.4, and then color development was carried out.
The number of areas with spotty desensitization was measured. [0057] As a result, no spot failure was observed in the test section of the present invention using wood kraft pulp in which the number of discolorations due to silver discoloration reaction was 2.25 per A-4. On the other hand, in a test outside the present invention using wood craft pulp in which the number of discolorations due to silver discoloration reaction was 28 per A-4, there were several spots of fogging and more than 10 spots of fading per A-4. The feeling was recognized. Example 5 The number of silver discolorations used in Example 2 was 2.25 per A-4.
A base paper for a support for a photosensitive material was produced in the same manner as in Example 1, except that the basis weight of the base paper was 135 g/cm 2 using wood kraft pulps of 1 and 28. [0059] After that, low density polyethylene resin (density 0.92 g/cm3, MFR 4.5 g/1
0 minutes) were melt-extruded and coated at a resin temperature of 330 DEG C. to a thickness of 18 .mu.m. At that time, both sides of the support for a photosensitive material were processed to have a paper-like matte surface. Next, a back coat layer containing silica particles having an average particle diameter of 4 μm after corona discharge treatment, gelatin of 1.0 g/m 2 and a hardening agent was coated on one side of the support for light-sensitive materials. Next, carbon black with an average particle size of 7 after corona discharge treatment was applied to the support surface opposite to the back coat layer.
Sulfur sensitization and gold sensitization achieve the highest sensitivity with an average particle diameter of 0.4μ, which has an undercoat layer consisting of μ silica particles and gelatin 3.5g/m2, a hardener, and a halogen composition of AgBr/AgCl = 5/95. Combined sensitization substantially [1,0
, 0] planes, and further contains gelatin necessary for film formation, as well as appropriate amounts of stabilizers, ortho sensitizing dyes, phenidone, coating aids, hardeners, etc. were coated in multiple layers at a coating amount corresponding to 1.0 g/m2 of silver nitrate and 1.0 g/m2 of gelatin. After coating and drying, the emulsion layer was heated at 40°C for 3 days, and then a coating solution consisting of a copolymer of acrylamide and imidazole, hydroquinone, palladium sulfide cores, etc. was coated with palladium sulfide sol 1.0.
A light-sensitive material for a planographic printing plate was obtained by coating at a rate of g/m2. [0061] The coated and dried sample was kept in a roll at 50°C.
After storage at 81% for 4 days, the film was cut, followed by diffusion transfer development, and the number of spot defects was counted. As a result, in the sample of the present invention using wood kraft pulp in which the number of discolorations due to silver discoloration reaction was 2.25 per A-4, no spot-like failure was observed at all. On the other hand, in a sample other than the present invention using wood craft pulp in which the number of discolorations due to silver discoloration reaction was 28 per A-4, there were many spot failures in which transferred silver was missing or thinned in spots. Admitted. Example 6 In Example 1, the oxygen delignification treatment conditions were changed to the following conditions (
The same procedure as in Example 1 was carried out except for setting 1) or (2), and the same results as in Example 1 were obtained. Condition (1): The pulp concentration is 20 wt% as the bone dry weight of unbleached pulp, and the added amounts of caustic soda and oxygen are 3 wt% and 2.1 w, respectively, based on the bone dry weight of unbleached pulp.
t%, treatment temperature and treatment time were 110℃ and 3, respectively.
It is 0 minutes. Condition (2): The pulp concentration is 27 wt% based on the bone dry weight of unbleached pulp, and the amounts of caustic soda and oxygen added are 2.0 wt% and 1, respectively, based on the bone dry weight of unbleached pulp.
．． 5 wt%, treatment temperature and treatment time were 98° C. and 2 hours, respectively. Example 7 The same procedure as in Example 1 was carried out except that instead of caustic soda as the alkali, oxidized white liquor was used as the caustic soda component in the same amount as in Example 1, and the same results as in Example 1 were obtained. Obtained. Effects of the Invention The present invention provides an excellent support for a photosensitive material, which has a paper substrate mainly composed of natural pulp, in which the tendency of spot failure to occur in a silver halide photosensitive layer is significantly suppressed. The body can provide.

Claims (6)

[Claims] 1. A support for a photosensitive material comprising a base paper containing natural pulp as a main component and coated with a resin capable of forming a film, wherein part or all of the natural pulp constituting the base paper is a natural kraft pulp, After the natural kraft pulp is cooked by the kraft method, it is washed in the presence of an antifoaming agent or a foam suppressor in the unbleached stage, and is subjected to oxygen delignification treatment before and after the washing treatment, and then bleached in the subsequent bleaching stage. The number of discoloration caused by the silver discoloration reaction defined below of the natural kraft pulp is A-4.
A support for a photosensitive material, characterized in that each support has 20 or less pieces. Number of discoloration caused by silver discoloration reaction: Tappi
A natural kraft pulp sample (sample conditions include basis weight: 750 g/m2 ± 150 g/m2, bone dry moisture content: 2) on the silver surface of a silver plate prepared based on standard T444.
0% by weight ± 5% by weight, pH; pH of pulp suspension when prepared based on Tappi standard T205
6.0 to 7.5) were tightly sealed in a black plastic bag, a load of 2.5 kg was applied to each A-4, and the temperature was 5.
A heating treatment was performed at 0° C.±1° C. and a relative humidity of 81%±2% for 50 hours, and then the number of silver discoloration reactions occurring on the silver surface was counted. 2. The support for a photosensitive material according to claim 1, wherein the resin capable of forming a film is a polyolefin resin. 3. The support for a photosensitive material according to claim 2, wherein the polyolefin resin is a polyethylene resin. 4. The support for a photosensitive material according to claim 1, 2 or 3, wherein the antifoaming agent or foam suppressing agent contains mineral oil as a component. 5. The total amount of antifoaming agent or foam suppressing agent is 0.1 kg to 1 ton per ton of bone dry weight of unbleached pulp.
．． The support for a photosensitive material according to claim 1, 2, 3 or 4, which weighs 5 kg. Claim 6: The number of discolored particles due to silver discoloration reaction is A
-Claims 1, 2, 3, and 4 in which the number of pieces is 10 or less per 4.
or 5. The support for a photosensitive material according to 5.