JPH0469648A - Base for photosensitive material - Google Patents

Abstract

PURPOSE:To drastically suppress the tendency to generation of dot trouble in a silver halide photosensitive layers by using natural draft pulp having specific characteristics. CONSTITUTION:A part or the whole of the natural pulp constituting base paper is the natural draft pulp. The natural draft pulp is formed by subjecting the pulp to a washing treatment in the presence of a defoaming agent or foam suppressor in the unbleaching stage after digestion by a kraft method, then subjecting the pulp to a bleaching treatment in the bleaching stage after this stage. In addition, the number of the points where the discoloration by the silver discoloration reaction arises of the natural kraft pulp is <=20 pieces per A-4. The number of the point where the discoloration by the silver discoloration reaction arises refers to the number of the points where the silver discoloration reaction arises on the silver surface measured after bringing a natural kraft pulp sample into tight contact with the silver surface of the silver surface plate prepd. in accordance with Tappi standard T444, sealing the sample into a black polyethylene bag, applying 2.5kg load per A-4, and subjecting the sample to a heating treatment for 50 hours under the conditions of 50 deg.C+ or -1 deg.C temp. and 81%+ or -2% relative humidity.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a resin-coated paper-type support for photosensitive materials, in which a paper base (hereinafter referred to as base paper) mainly composed of natural pulp is coated with a film-forming resin, preferably a polyolefin resin. More specifically, the present invention relates to a resin-coated paper-type support for a light-sensitive material having good photographic suitability for a silver halide light-sensitive layer.

[Prior Art] As a support for a photosensitive material, a resin-coated paper type support for a photosensitive H material, in which at least one side of the substrate is coated with a film-forming resin, is well known. 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, the resin-coated paper-type support for photosensitive materials, in which a base paper mainly composed of natural pulp is coated with a resin capable of forming Filno, still has some serious problems in terms of photographic suitability for silver halide photosensitive layers. It had a score of 7. Therefore, when a silver halide photosensitive material is stored after production using a resin-coated paper as a support, which is a base paper mainly composed of natural pulp coated with a resin capable of forming a film, it is necessary to store it for a long period of time, especially at high temperatures. , if stored under high humidity,
The silver halide of the light-sensitive material is fogged in spots, and the unexposed areas can be developed in spots during the development process, or the sensitivity of the light-sensitive material is decreased or increased in spots. There was a problem with this. 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 spotty fog is sometimes more than 20 mm in diameter.
It can even reach the point where the photographic paper becomes 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 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 C1 support, spots are observed. In addition to the occurrence of fog, the yellow and magenta coloring layers in particular cause a decrease in sensitivity in spots, and the color balance of the image is affected in spots (the commercial value of the photographic paper is lost, -). was there. 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. Additionally, there are several proposals regarding the photographic properties of supports for light-sensitive materials. Japanese Patent Publication No. 54-9844 proposes a fog-proof, 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. However, it was extremely insufficient in preventing spot failures in silver halide light-sensitive materials having such a support. In addition, regarding photographic paper, JP-A No. 52-65423 and JP-A No. 58-
No. 43730 proposes to eliminate the adverse effects on photographic properties caused by the decomposition of cationic electrolytes and additive chemicals for paper, respectively, and silver halide photosensitive materials using resin-coated paper made of these photographic papers as a support. However, it has become clear that spot failures cannot be prevented at all, and that spot failures are caused by a mechanism completely different from the mechanism described in these specifications. Furthermore, techniques for improving the photographic properties of unbleached kraft paper have been proposed in JP-A-2-96741, JP-A-2-99689, and JP-A-2-99693. According to them, the photographic properties of bleached kraft paper are good, but the photographic properties of unbleached kraft paper are poor, and this is due to residual propylene oxide and/or silicone, which are antifoam components used in the unbleached stage. It has been proposed to improve the photographic properties of unbleached kraft paper by specifying the antifoaming agent containing these components and the cold water extraction pH. 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, Japanese Patent Publication No. 58-43732 discloses a technique for improving the shelf life of silver halide photographic materials by using a resin-coated paper consisting of a base paper whose main component is natural pulp that has been bleached with alkaline peroxide. However, even with the use of the resin-coated paper, it was insufficient to prevent spot failures. Furthermore, the special public service 59-3857
No. 5 proposes a technique for preventing fogging and spots in silver halogenide photographic materials by using photographic paper using water-use pulp obtained by oxygen pulping. Even with the use of resin-coated paper with a substrate of 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 film-forming resin, and the occurrence of spot failures, as shown in the following. The mechanism or cause of occurrence is completely unknown, and it has not been possible to improve spotty failures 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, which is capable of forming a film, and which has a markedly suppressed tendency to cause spot failures in a silver halide photosensitive layer. An object of the present invention is to provide a support for a photosensitive material coated with a certain resin. Other objects of the invention will become apparent from the description below.

〔Example〕

Next, examples will be described in order to explain the present invention more specifically. Example 1 Production of hardwood kraft pulp1. In the culm, as a process condition, the 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 for bone-dry pulp, 0.7 kg per ton, and 4.0 kg per ton. ,1
．． ．． 5kg or 2. The electrical conductivity of the unbleached thickener as defined in the Okg1 specification is 4.5μQ7'Cn1s i
ooμj5/”cm or 1, i',, i 0 It
○/' Cm, and the final rejection rate of the liquid number Ikron method cleaner is −rO,01 compared to bone-dry pulp.
w1%, 0.02wt%, 0. 05wt% or 0.05wt%
i, wt, %, and the combinations listed in Table 1 (adjusted to J, and adjusted other L conditions as appropriate 1-7,
The silver amount color reaction defined in the specification is 1. The number of discoloration occurrences is as shown in Table 1, 1-CE 11 T) P DI
The broad-based bleached graft pulps listed in Table 1 were obtained by bleaching in the following manner. In addition, the presence of antifoaming agent is 0.1
．． On the other hand, if it was less than 11 g, the foaming prevention was insufficient. Next, add each pulp to Canadian Stanter 1
... Beating to freeness 320ml, and pulp 1.
Caodinated starch 3Qi (4+1
part, 0.2 parts of anionized polyacrylamide,
0.4 parts by weight of argyl ketene dimer emulsion (ketendarmer) and 0.4 parts by weight of polyaminopolyamide gobichlorohydrin resin were added, and the basis weight was 1. , O
A paper of Og/rd was produced. The obtained wet paper was dried at 110°C, and then 3 parts by weight of carboxy-modified polyvinyl alcohol, 0.05 parts by weight of optical brightener, and 0.0 part of blue dye were added.
02 parts by weight, 2 parts by weight of sulfuric acid, and 97 parts by weight of water at 25 g/n (impregnated), dried with hot air at 110°C, and further heated under a linear pressure of 90 kg/cm with super-
After calendering, both surfaces are treated with corona discharge to produce a base paper for a support for photosensitive materials. Next, low-density polyethylene resin (density 0.
92g/cm”, MFR=8.5g/10min) 4
Dioxide consisting of 450% by weight of anatase type titanium dioxide surface treated with 7.5% by weight, hydrated aluminum oxide (0.75% by weight as 3 parts of Al2O to titanium dioxide) and 2.5% by weight of zinc stearate. 20 parts by weight of titanium pigment masterbatch, low density polyethylene resin (density 0.92 g/cm', MFR=4.5 g/1)
0 minutes) and 65 parts by weight of high-density polyethylene resin (density 0.0 minutes).
A resin composition consisting of 15 weight M parts (97 g/cm3, VFR=7.0 g/10 minutes) was melt-extruded and coated 7 times to a thickness of 13 microns at a resin temperature of 330°C. 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/cm
"M FR2g/10 minutes) 15 parts by weight and high density polyethylene resin (density 0.96g/cm3, MFR20g/
A resin composition consisting of 85 parts by weight (IO) was heated to a resin temperature of 33
The surface of the resin layer containing the titanium dioxide pigment of the photosensitive material support produced in this way was coated by melt extrusion at 0"C to the same thickness as the surface, and the surface of the resin layer on the back was slightly rough. The surface quality was processed to a paper-like matte surface. After that, the back side of the photosensitive material support was treated with a corona discharge and then dried, and the composition was C colloidal silica: stylene acrylic oxide = 1.1. A back coat layer of 0.4 g/n (coating (7) is applied. Next, an emulsion layer and its protective layer are applied after corona discharge treatment on the front resin surface of the photosensitive material support including the titanium monooxide face. -C A black and white photographic paper was obtained with a 12-0 emulsion layer of 1, (I
II) Gelatin 1.4. in the presence of potassium 1.2X, 1.05 g. /AgB r/AgC produced by producing and dispersing 49.2g of silver halide particles with silver nitrate in /Ig
Average particle size 0 with a halogen composition of I=65/35
．． Including a neutral method silver halide photographic emulsion consisting of 1,0,03 planes sensitized by both sulfur sensitization and gold sensitization to a maximum sensitivity of 6μ, and gelatin necessary for film formation. Wrap appropriate amounts of stabilizers, sensitizing dyes, coating aids, hardeners, optical brighteners, thickeners, filter dyes, etc., and coat with silver nitrate.
2p, /d, gelady> was applied in a multi-layer coating 4j with a coating amount corresponding to 4.4g, ・a. Protective layer is 2g/n
(Contains coating aids and hardeners in addition to gelatin equivalent to 100% gelatin.) The coated and dried sample was stored at 50°C and 80% for 4 days.
After that, it was developed in black and white, and the number of speckled fogs was measured. The results obtained are summarized in Table 1. (Hereafter 1/Margin) 34 (Note 1) ○ indicates the present invention. (Note 2) The number is the average value of n = 4. As can be seen from Table 4, the samples of the present invention using wood crat pulp in which the number of discolorations due to the silver discoloration reaction defined in the specification was 20 or less per A, -4 did not cause spotty fogging. In wood pulp: 7ft pulp and 12, it is preferable that the number of discolored particles is 10 or more per A-4.
It can be clearly seen that 5 or less per -4 is more preferable. Example 2 The procedure was carried out in the same manner as in Example 1, except that the following materials were used instead of the wood crat pulp used in Example 1. In the second step of manufacturing hardwood kraft pulp, the process conditions include the presence of an oil-based antifoaming agent containing mineral oil as a component in the washing stage of unbleached kraft pulp. 1 (g, 0゜7kg, 1.
Okg, 1.5kg or 2.0kg1 Calcium content in unbleached kraft pulp as defined in the specification is 300
0ppm, 4000ppml or 5500ppm
I) of Kura7I pulp slurry at z and chlorine stage
H is pH 1-, 5, pH 2, 0, or pH 2, 7, and the combinations listed in Table 2 are adjusted, and other process conditions are appropriately adjusted to produce discoloration by a silver discoloration reaction defined in the specification. The number of occurrences is as shown in Table 2, I
The hardwood bleached pulps listed in Table 2 were each obtained by bleaching in the manner of CE HD P D I. The results obtained are shown in Table 2. (hereinafter referred to as "margin"): 4'i As can be seen from Table 2, the wood kraft pulp of the present invention in which the number of discoloration due to silver discoloration reaction defined in the specification is 20 or less per A-4 is used. The sample has little occurrence of spot fog, and as a wood craft pulp, the number of discolored particles is preferably 1-0 or less per A-4, and more preferably A-4.
It is clear that 5 or less pieces per unit is preferable. Example 3 The number of discolorations caused by the silver discoloration reaction used in Example 1 was A-
The procedure was the same as in Example 1, except that wood kraft pulp with 2 pieces per 4 and 40 pieces was used, the basis weight of the base paper was 1.60 g / i, and the thickness of the front and back resin layers were each 30 μm. A support for a photosensitive material was obtained. Then, after corona discharge treatment, the following emulsion layer and its protective layer were provided on the front resin surface containing the titanium dioxide pigment of the support for a light-sensitive material to obtain a photographic paper. The emulsion layer is composed of potassium hexachloroiridium (III) 1-. A g B r produced by producing and dispersing silver halide particles equivalent to 9.6 g of silver nitrate in 4.8 g of gelatin in the presence of 0 x 10-5 g.
/ A g C1, = 95 / 5 with a halogen composition and an average particle diameter of 0. Contains a neutral method silver halide photographic emulsion consisting of a mixed crystal of [1.0.0] and [1,1-11] planes that is sulfur-sensitized to a maximum sensitivity of 8μ, and further contains a yellow color-forming coupler and film-forming material. In addition to the necessary gelatin, it contains appropriate amounts of stabilizers, blue sensitizing dyes, coating aids, hardeners, thickeners, etc., and the amount of silver nitrate is 0. 6g/r&, 1.5g with gelatin
A multilayer coating was performed together with the protective layer at a coating amount corresponding to /i. The protective layer contains gelatin equivalent to 1.5 g/nf as well as coating aids, thickeners, hardeners, etc. The coated and dried sample was 50°0180%/IFII?
After storage for 41 days, 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 performed.
The number of spots with spotty desensitization was measured. As a result, the number of discolored pieces due to silver discoloration reaction was 2 per A4 sheet.
No spot failure was observed in the sample of the present invention using wood kraft pulp. On the other hand, in a sample other than the present invention using wood kraft pulp in which the number of discolorations due to silver discoloration reaction was 40 per A-4, several speckled fogs and a large number of speckled desensitizations were observed per A-4. It was done. Example 4 Using the wood kraft pulp used in Example 1, in which the number of silver color occurrences was 2 and 40 per A, -4, the basis weight of the base paper was changed to ], 35 g/i. A base paper for a support for a photosensitive material was produced in the same manner as in Example 1. After that, low density polyethylene resin (density 0
．． 92g/cm3, MFR4, 5g/10min) were each melt-extruded coated to a thickness of 18μ at a resin temperature of 330°C. At that time, both sides of the support for a photosensitive material were processed to have a paper-like matte surface. Next, silica particles with an average particle diameter of 4 μm and gelatin 1.0 g/r after corona discharge treatment were applied to one side of the support for photosensitive materials.
A back coat layer containing ri and hardener was applied. Next, on the side of the support opposite to the back coat layer, an undercoat layer consisting of carbon black after corona discharge treatment, silica particles with an average particle size of 7 μm, gelatin 3°5 g/rd, and a hardening agent, and A, g B r /A , g C1,= 5
/95 halogen composition with an average particle size of 0.4μ
Contains a neutral silver halide emulsion consisting essentially of [1-10,0] planes sensitized by sulfur sensitization and gold sensitization to the maximum sensitivity of An emulsion containing a stabilizer, an ortho sensitizing dye, phenidone, a coating aid, a hardening agent, etc. was mixed with a silver nitrate amount of 1. , Og/%, and the coating corresponding to 1.0 g/m of gelatin was coated in multiple layers. After coating and drying, the emulsion layer was heated at 40°C for 1 hour, 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. A photosensitive material for a planographic printing plate was obtained by coating with Og/Ilf. The coated and dried sample was rolled at 50℃ and 80%.
After being stored for a while, it was cut, followed by diffusion transfer development, and the number of spot defects was counted. As a result, the number of discolored pieces due to silver discoloration reaction was 2 per A4 sheet.
No spot failure was observed in the sample of the present invention using wood kraft pulp. On the other hand, in a sample other than the present invention using wood kraft pulp in which the number of discolorations due to silver color reaction was 40 per A-4, spot failures in which transferred silver was missing or thinned in spots occurred. Many were recognized.

【Effect of the invention】

According to the present invention, it is possible to provide an excellent support for a photosensitive material whose base paper is paper mainly composed of natural pulp, in which the tendency of occurrence of spot failure in the silver halide photosensitive layer is significantly suppressed.

Claims (1)

[Scope of Claims] 1) A support for a photosensitive material in which a base paper containing natural pulp as a main component is coated with a resin capable of forming a film, wherein part or all of the natural pulp constituting the base paper is natural kraft pulp. The natural kraft pulp is digested by the kraft method, washed in the presence of an antifoaming agent or a foam suppressant in the unbleached stage, and bleached in the subsequent bleaching stage, and the natural kraft pulp is 1. A support for a photosensitive material, characterized in that the number of kraft pulp that undergoes discoloration due to a silver discoloration reaction defined below is 20 or less per A-4. Number of discoloration caused by silver discoloration reaction: Natural kraft pulp sample (sample conditions: basis weight: 750 g) on the silver surface of a silver plate prepared based on Tappi standard T444
/m^2±150g/m^2, absolute dry moisture content: 20% by weight
±5% by weight, pH; 6 as the pH of the pulp suspension when prepared based on Tappi standard T205.
0 to 7.5) and sealed in a black plastic bag,
- Applying a load of 2.5 kg per unit, temperature 50℃±1℃
A heating treatment was performed for 50 hours at a relative humidity of 81%±2%, 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) Claims 1 and 2, wherein the antifoaming agent or antifoaming agent contains mineral oil as a component.
or 3. The support for a photosensitive material according to 3. 5) Claim 1, wherein the amount of antifoaming agent or antifoaming agent is 0.1 kg to 1.5 kg per ton of bone dry weight of unbleached pulp.
, 2, 3 or 4, the support for a photosensitive material. 6) The number of discolorations due to silver discoloration reaction is 10 per A-4.
6. The support for a photosensitive material according to claim 1, 2, 3, 4 or 5, wherein the support is less than or equal to 1.