JPH0555052B2 - - Google Patents

Description

[Detailed description of the invention]

(Field of the Invention) The present invention relates to photographic paper, and more particularly to photographic paper that can be used as postcards. The present invention also relates to a photographic paper which can be used as a postcard and which prevents pigment from falling off from the back coat layer. (Prior art) Conventionally, baryta paper has been used as photographic paper, but in order to speed up the development process, so-called water-resistant photographic paper, in which both sides of the base paper are coated with polyolefin, has been developed. It now accounts for the majority of that amount. Usually, this water-resistant photographic paper has a polyethylene layer containing an inorganic pigment such as titanium oxide on one side, and a photographic emulsion layer is provided on that side. The surface on which this photographic emulsion layer is provided is called the surface. The opposite side, the side without the emulsion layer, is called the back side. In order to use photographic paper as a postcard, you must write or draw pictures on this back side. When stamped, it is necessary that the ink dries quickly, that the ink does not fall off due to friction, and that the ink does not bleed. However, as mentioned above, the side of photographic paper opposite to the image is coated with a hydrophobic and soft polyolefin resin, so it is difficult to write on it with a pencil or pen, and it is also difficult to write on it with a stamp. Even if you press the ink, it takes a long time to dry because it is essentially non-absorbent, and even after drying, the ink can easily fall off due to friction, contact, etc., contaminating the surrounding area, or in extreme cases, the stamp may disappear completely. It disappears and its purpose cannot be achieved. In order to achieve such an objective, it is known in the art to provide a backcoat layer essentially consisting of a liquid-absorbing inorganic pigment and a binder on the side of the hydrophobic support opposite the image of the photographic paper. For example, in JP-A-58-184144, a preferred embodiment includes 15 to 50 parts by weight of an inorganic pigment with an oil absorption of 100 c.c./100 g or more, 85 to 50 parts by weight of gelatin, and 0.20 parts by weight of gelatin. A backcoat layer is disclosed that includes a specific hardener of gelatin from % to 3.0% by weight. However, in this method, when the amount of liquid-absorbing inorganic pigment used is small, the ink absorption rate is slow, and the back coat surface remains wet with ink for a long time, making handling inconvenient. In addition, if the liquid-absorbing inorganic pigment has a high liquid-absorbing ability and occupies a high proportion in the back coat layer, the wetting of the back coat surface by ink will be reduced, but the tendency of the ink to bleed will increase, and in extreme cases, the characters will disappear. becomes difficult to decipher. Furthermore, such inorganic pigments have poor adhesion to the binder and fall off from the back coat layer during the photographic processing process, contaminating the photographic developing apparatus. (Object of the Invention) Therefore, an object of the present invention is to provide a photographic paper that has good writing suitability with various writing instruments and prevents pigment from falling off from the back coat layer. . (Structure of the Invention) In order to overcome the above-mentioned drawbacks, the present inventors, as a result of intensive research, found that 1. gelatin and 2. average pore diameter of 100 Å or less were added on the back side of a resin-coated paper-type photographic support. The above object was achieved by providing a back coat layer containing porous silica and 3. a hardening agent for gelatin in an amount of 3% to 10% by weight of gelatin. In carrying out the present invention, the amount of gelatin and porous silica to be used is preferably in the range of 2:1 to 1:2 by weight, and the coating amount of porous silica is 0.5 g/m ²
to 5.0g/ ^m2 , particularly preferably
A range of 0.7g/ ^m2 to 2.5g/ ^m2 is good. If the amount of porous silica is too small relative to the gelatin, sufficient ink absorption capacity will not be obtained and the ink will dry slowly, and if it is too large, it will tend to bleed. If the amount of porous silica applied is too small, sufficient ink absorption ability will not be obtained and the ink will dry slowly. On the other hand, if the amount is too large, not only will the physical properties of the curl deteriorate and the productivity will deteriorate, but also the adhesion to the binder will decrease and the pigment will fall off from the back coat layer. Gelatins used in the practice of this invention include lime-processed gelatin, acid-processed gelatin, enzyme-processed gelatin, and gelatin derivatives such as gelatin reacted with anhydrides of dibasic acids, etc., which are commonly used in the art. Any material can be used. The porous silica used in the practice of the present invention is preferably porous silica having an average pore diameter of 100 Å or less. When the average pore diameter becomes 100Å or more,
Adhesion to gelatin decreases and pigments fall off during development. There is no particular limit to the average particle size, but
If the thickness exceeds 10μ, the back coat surface will become rough.
Preferably less than 10μ. Representative trade names of porous silica used in the practice of the present invention include Thyroid-63, -65, and -66 (Fuji Davison Chemical Co., Ltd.).
etc. are known. It is advantageous to use hardening agents for gelatin in the practice of this invention. The amount of the hardening agent for gelatin used is preferably in the range of 0.3% to 10% by weight based on the amount of gelatin used. Gelatin hardeners that can be used in the practice of this invention include N,N'-ethylenebis(vinylsulfonylacetamide), 1,3,5-triacryloyl-hexahydro-S-triazine, and the like. Active vinyl compound, 2,4-dichloro-6-
Active halogen compounds such as hydroxy-S-triazine sodium salt, epoxy compounds such as glycerol triglycidyl ether, 1,6
-Ethyleneimino compounds such as -hexamethylene-N,N'-bisethylene urea, isocyanate compounds such as 1,6-hexamethylene diisocyanate, and other hardening agents for gelatin commonly used in photographic emulsions can be used, but aldehyde Compounds can lead to contamination of the backcoat layer, especially when formalin or formalin-releasing compounds are used in the backcoat layer of a photographic paper, and can fog the adjacent emulsion, and when the paper is a color paper, couplers, especially when the paper is a color paper. Its use should be avoided because it reacts with magenta couplers and causes undesirable coloration. In carrying out the present invention, a thickener may be used as appropriate to adjust the viscosity of the coating liquid for base coat. Thickeners that can be used in the practice of this invention include starch, starch derivatives, sodium alginate, guar gum, locust bean gum, xanthus cum,
Hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose, cellulose sulfate ester salt, styrene maleic anhydride copolymer,
Examples include various types such as methyl vinyl ether maleic anhydride copolymer. In carrying out the present invention, toning agents, brighteners, fillers, PH regulators, coating aids, etc. can be used in appropriate combinations. Examples of the hydrophobic support used in the practice of the present invention include resin-coated paper in which a paper substrate is coated on both sides with a film-forming resin such as polyolefin, polystyrene, or polyvinyl chloride, often with a polyolefin resin. can. In particular, polyolefin resin-coated paper is advantageously used because of its good processability. In addition, the resin layer of these resin-coated papers contains white pigments such as titanium oxide, zinc oxide, talc, and calcium carbonate, fatty acid amides such as stearic acid amide and arachidic acid amide, zinc stearate, magnesium stearate, and palmitin. It is preferable to contain various additives such as dispersants such as fatty acid metal salts such as calcium acid salts, pigments and dyes such as ultramarine and cobalt violet, antioxidants, optical brighteners, and ultraviolet absorbers in appropriate combinations. The polyolefin resin-coated paper which is advantageously used in the practice of the present invention is manufactured by extrusion coating a molten polyolefin resin onto a running base paper through a slit die in the form of a film. At that time, it is desirable to activate the base paper surface by corona treatment, flame treatment, etc. prior to melt extrusion coating. The thickness of the coating resin layer is not particularly limited, but it is generally advantageous to have a thickness of about 5μ to 50μ. The side of the polyolefin resin-coated paper on which the silver halide photographic constituent layer is provided has a glossy surface, matte surface, silky surface, etc. depending on the purpose, and the back surface is usually a matte surface. Polyolefin resins for coating polyolefin resin-coated paper that are advantageously used in carrying out the present invention include low-density polyethylene, high-density polyethylene,
Examples include homopolymers of olefins such as polypropylene, polybutene, and polypentene, copolymers of two or more olefins such as ethylene-propylene copolymers, and mixtures thereof. (hereinafter simply abbreviated as MI) can be used alone or in combination. The base paper for the polyolefin resin-coated paper may be ordinary natural pulp paper, synthetic resin paper, or so-called synthetic paper made of synthetic resin film, but it may also be made of softwood pulp, hardwood pulp, or wood mixed with softwood and hardwood pulp. Natural pulp paper based on pulp is advantageously used. There are no particular restrictions on the thickness of the base paper, but paper with good surface smoothness is preferred, and its basis weight is preferably 50 g/m ² to 250 g/m ² . Furthermore, the base paper mainly composed of natural pulp can contain various polymer compounds and additives. For example, starch derivatives, polyacrylamide, polyvinyl alcohol derivatives,
Dry paper strength enhancers such as gelatin, sizing agents such as fatty acid salts, rosin derivatives, dialkyl ketene dimer emulsions, wet paper strength enhancers such as melamine resins, urea resins, and epoxidized polyamide resins, stabilizers, pigments, dyes, Optical brighteners, latex, inorganic electrolytes, PH adjusters, etc. can be contained in appropriate combinations. In carrying out the present invention, the apparatus for applying the back coat coating liquid onto the surface of the hydrophobic support opposite to the surface on which the silver halide photographic constituent layer is provided include an air knife coater, a roll coater, a bar coater, a blade coater, and a slide coater. Examples include hopper coaters, gravure coaters, flexogravure coaters, and combinations thereof. Prior to coating, it is desirable to activate the surface of the hydrophobic support by corona treatment, flame treatment, or the like. Various drying devices are used to dry the applied coating liquid, including hot air dryers such as straight tunnel dryers, arch dryers, air loop dryers, and sine curve air float dryers, and dryers that use infrared rays, heated dryers, microwaves, etc. can be given. The silver halide photographic emulsion layer according to the present invention includes various types. Examples include photographic emulsion layers for enlargement positives, photographic emulsion layers for contact positives, photographic emulsion layers for negatives, color photographic emulsion layers, photographic emulsion layers for printing, photographic emulsion layers for direct positives, and photographic emulsion layers for diffusion transfer. In addition, such photographic emulsion layers contain binders such as gelatin and gelatin derivatives, chemical sensitizers such as hypo, noble metal sensitizers such as gold salts and platinum salts, hexahalogenoiridium () complexes, hexahalogenodium () complexes, etc. etc., nucleic acid decomposition products, crystal habit modifiers for silver halide grains such as mercapto heterocyclic compounds described or exemplified in JP-A-50-147925 and JP-A-51-107129;
Color sensitizers, stabilizers, antifoggants, color photographic couplers, hardeners, dihydroxypenzene compounds, coating aids, or It can contain fogging agents, additives for direct positive photographic emulsions such as dyes for direct positive photographs, dye developers, and other additives. The silver halide photographic material according to the present invention can be used for exposure, development, etc. as described in "Photographic Light-sensitive Materials and Handling Methods" (Kyoritsu Shuppan, written by Goro Miyamoto, Photographic Technology Course 2), depending on the photographic material. stop, fix, bleach,
Multi-layer silver halide color photographic materials, which undergo one-bath bleach-fixing treatment after color development, are treated with stabilizers, CD-, CD- (the above two compounds are trade names of Kodatsu Co., Ltd.), droxychrome ( It can be processed with any color developer, such as May & Baker Co., Ltd. (trade name). Benzyl alcohol, thallium salt, phenidone, etc. may be added to the developer containing such a main agent. Also, useful one-bath bleach-fix solutions are solutions of metal salts of aminopolycarboxylic acids (e.g., ferric complex salts such as ethylenediaminetetraacetic acid, propylenediaminetetraacetic acid, etc.), and fixing agents include sodium thiosulfate, thiosulfate, etc. Ammonium sulfate and the like are useful.
Such a one-bath bleach-fix solution can contain various additives. For example, desilvering accelerators (e.g. mercaptocarboxylic acids as described in U.S. Pat. No. 3,512,979, mercapto-heterocyclic compounds as described in Belgian Patent No. 682,426, etc.), antifouling agents, PH regulators or PH buffers, dura mater Various compounds such as agents (for example, magnesium sulfate, aluminum sulfate, potassium alum, etc.) and surfactants can be contained in combination. Also, although such one-bath bleach-fix solutions can be used at various PHs, useful PH
The range is PH6.0-8.0. E Example Next, in order to explain the present invention more specifically,
An example will be described. Example 1 Paper with a basis weight of 160 g/m ² was used as the base paper, and one side of it was coated with 9% by weight titanium oxide and 21% by weight low-density polyethylene for kneading titanium oxide (density
0.918, MI8.5), 45% by weight low density polyethylene (density 0.918, MI5.0), 25% by weight high density polyethylene (density 0.965, MI7.0), resin thickness 30μm
50% by weight low density polyethylene (density 0.918, MI5.0),
50% by weight high-density polyethylene (density 0.965,
After corona discharge treatment of the matte surface of resin-coated paper having a matte resin layer of resin (MI7.0) with a thickness of 30 μm, the coating liquid listed in Table 1 was applied with an air knife coater, dried, and photographed. A support for this purpose was manufactured. The coating amount was 20 g/m ² (moisture).

[Shedding of pigment]

The amount of white powder (pigment) generated when the back side of the sample and a nylon scrubber were rubbed together under a constant load was examined, and the ability of the pigment to fall off was determined. Evaluation criteria: ○Does not occur at all. △ Occurs a little. x Generated in large amounts (most of the back coat layer has been removed) The results are shown in Table 2.

[Table] As is clear from Table 2, all of the samples of the present invention were in good condition with no pigment coming off, and there were no problems in writability. However, among samples other than those of the present invention, it can be seen that samples with good writability have poor pigment shedding, and samples with good pigment shedding have poor writability with an oil-based pen.

Claims (1)

[Scope of Claims] 1. A resin-coated paper-type photographic support in which both sides of a base paper are coated with resin has a silver halide photographic constituent layer on one side, and at least on the opposite side of the support. A photographic paper comprising: a gelatin b porous silica having an average pore diameter of 100 Å or less c a back coat layer containing a hardening agent for gelatin in an amount of 3% to 10% by weight based on gelatin.