JP3053134B2 - Photographic support - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to a photographic support,
In particular, the present invention relates to a photographic support in which a back coat layer is provided on the side of the support opposite to the surface on which the photosensitive layer is provided, thereby preventing curling when the silver halide photographic photosensitive layer is provided.

[0002]

2. Description of the Related Art In a silver halide photographic light-sensitive material, in particular, a light-sensitive material using a thin resin-coated paper type support, gelatin in a silver halide photographic light-sensitive layer expands and contracts due to a change in environmental humidity, and a low humidity. In the case of (1), there is a problem that the curl is made with the photosensitive surface inside, and in the case of high humidity, the curl is performed in the opposite direction.

When such a curl occurs, for example, when the paper is conveyed by an automatic conveyance device, a conveyance trouble is likely to occur, and the photographic paper processed by the automatic developing machine is bulky and difficult to handle. When re-photographing from the developed photographic paper, it causes a problem that the image cannot be photographed well.

It is conceivable to reduce the amount of the hydrophilic colloid in the silver halide emulsion layer in order to prevent curling. However, such means may cause deterioration of photographic characteristics, for example, increase in fog or reduction in graininess. In addition, not only does the abrasion resistance deteriorate, but also there is a limit to weight reduction, so that the curl suppressing effect itself is generally insufficient.

Therefore, in order to prevent the curl, the photographic support is provided with a back coat layer formed by aqueous coating mainly using gelatin as a binder in an amount corresponding to the amount of the hydrophilic colloid of the silver halide photographic material. Required, the amount of backcoat applied must be quite large.

Conventionally, in order to form such a back coat layer having a large coating amount, a back coat has been separately applied to a resin-coated paper manufactured in advance by a special coater and dried due to a demand for drying ability. In this manufacturing method, the process management becomes complicated due to the large number of processes, which is not only economically disadvantageous, but also because the support is extended many times, the support surface is exposed to dust in the air. There is a problem that the danger increases.

On the other hand, a back coat layer coating / drying apparatus is incorporated into a resin melt coating apparatus system for producing a resin-coated paper by melt-extruding a resin from a slit die into a film on a running base paper. In a so-called on-machine coating method in which a resin-coated paper-type photographic support is manufactured and a backcoat layer is provided before the resin-coated paper is wound, the drying time tends to be shorter due to limitations on the apparatus. Was.

When the concentration of the coating liquid is concentrated so that the coating can be performed even with such a restricted coating and drying apparatus, the viscosity of the coating liquid increases, which causes a problem that the coating becomes difficult.

[0009]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an inexpensive photographic support provided with a back coat layer and having an excellent curl prevention ability in a coating apparatus having a small drying ability on a resin-coated paper manufacturing apparatus. There is to provide.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide a resin-coated paper-type photographic support having a paper substrate as a base material and coated on both sides with a resin capable of forming a film. And a hydrophilic back coat layer on the opposite side, and the binder of the back coat layer has a viscosity η determined by the PAGI method of 1.
2 cPs to 2.0 cPs , the peak value of the molecular weight distribution is 8,
000 to 20,000, average molecular weight of 17,000
Gelatin in the range of 60,000 to 60,000 , and the coated amount of gelatin contained in the back coat is 0.7 g dry weight.
/ M ^{2 to} 5.0 g / m ² .

When the viscosity is less than 1.2 cPs, the curl suppressing effect of the back coat layer becomes insufficient,
If it exceeds 2.0 cPs, the back coat surface will be uneven as a result.

[0012] Gelatin having a viscosity η of 1.2 cPs to 2.0 cPs determined by the PAGI method used in the practice of the present invention can be obtained by subjecting ordinary gelatin to an enzymatic decomposition treatment, an alkali hydrolysis treatment, or a low molecular weight component in an extracted fraction. The enzyme-treated gelatin is advantageous from the viewpoint that the adjustment of the physical properties is relatively easy. As a raw material of the gelatin used in the practice of the present invention, beef bone, pork skin, etc. are not particularly limited, and any material can be used.

The gelatin used in the practice of the present invention has a peak molecular weight distribution of 8,000 to 20,000, an average molecular weight of 17,000 to 60,000,
The jelly strength shows 10 to 90 Bloom.

The coating amount of the back coat used in the practice of the present invention is desirably 0.7 to 5.0 g / m ² as a dry weight of gelatin contained therein. More preferably, the amount is 1.5 to 3.5 g / m ² . If the coating amount is too small, the effect of preventing curl when processed into photographic paper becomes insufficient, while if it is too large, drying is insufficient with a dryer of an automatic developing machine during development processing, and the photographic paper is soiled. The amount of moisture applied to the back coat according to the present invention is preferably 5 to ²⁰ g / m ^{2 in} consideration of the drying ability of the apparatus.

The use of such a low-viscosity gelatin is described in Japanese Patent Publication No. 59-37818 by using a gelatin of 5.7 cPs or less in the non-photosensitive layer during simultaneous multilayer coating.
It has been shown to improve gloss and tailing after development. According to the text, the effective viscosity range is 3.0 to 5.1.
It is considered to be cPs, and at such a viscosity, a high-concentration coating liquid will have a high viscosity, and it will be difficult to perform stable coating, and the resulting coated surface will be non-uniform.

Various additives can be contained in the backcoat layer used in the practice of the present invention. For example, as hardeners, organic hardeners such as formalin, reaction products of formaldehyde with urea or melamine, halogen carboxylic acids, vinyl sulfone compounds, aziridine compounds, epoxy compounds, active halogen compounds, acryloyl compounds, isocyanate compounds, Chromium alum, inorganic hardeners such as zirconium carbonate, anionic surfactants such as alkylbenzene sulfonates and sulfosuccinates as surfactants, nonionic surfactants such as saponin and alkylene oxide compounds, Ampholytic surfactants such as amino acids, aminosulfonic acids, esters of amino alcohols and the like can be used.

As the antistatic agent, various inorganic and organic antistatic agents are useful. Preferred inorganic antistatic agents include, for example, colloidal silica. Preferred organic antistatic agents include, for example, unsaturated copolymerizable monomers having 4 or more carbon atoms such as sodium salt of styrene and maleic anhydride copolymer, sodium salt of isobutylene and maleic anhydride copolymer, and maleic anhydride. Alkali salt of copolymer with acid, natural or synthetic polymer having hydroxyl group such as cellulose, dextran, dextrin, alginic acid, starch, polyvinyl alcohol, preferably alkali salt of cellulose sulfate, alkali salt of polystyrene sulfonic acid , Sodium polyacrylates (eg, polyacrylic acid, polymethacrylic acid, poly-α-
And sodium salts of polyacrylic potassium and acrylic acid and methyl acrylate copolymer, and the like, and acrylic acids to be polymerized and alkali salts of acrylic acid copolymer.

The back coat coating device according to the present invention includes an air knife coater, a roll coater, a bar coater, a blade coater, a slide hopper coater, a gravure coater, a flexographic gravure coater, and the like.
A curtain coater, an extrusion coater, a combination thereof and the like can be mentioned. In addition, when the applicator section and the measuring section are separated, the applicator can be selected from various systems such as a dip system, a roll system, and an extrusion system.

As a back coat drying apparatus according to the present invention, a hot air dryer such as a straight tunnel dryer, an arch dryer, an air loop dryer, a sine curve air float dryer, etc., an infrared ray, a heating dryer, a microwave and the like are used. It can be selected from various drying devices such as a dryer. The application of the back coat according to the present invention may be performed at any stage after the resin layer is provided on the back surface, but in any case, the back coat application surface is subjected to a flame treatment, a corona discharge treatment, etc. before that. It is desirable to improve the coating liquid receptivity of the processed surface.

The base paper used in the practice of the present invention includes:
Normal natural pulp paper, synthetic fiber paper, or so-called synthetic paper made from synthetic resin film as pseudo paper may be used, but natural pulp paper mainly composed of softwood pulp, hardwood pulp, and softwood mixed pulp wood pulp is used. It is advantageously used. There is no particular limitation on the thickness of the base paper, but a base paper having good surface smoothness, such as applying pressure and compressing with a calender after papermaking the base paper, is preferable, and its basis weight is 40 g / m2. ^{2 to} 250 g / m ² is preferable, but the effect of the present invention is particularly advantageously exhibited at 40 g / m ² to 1.
20 g / m ² .

The base paper mainly composed of natural pulp, which is advantageously used in the practice of the present invention, can contain various polymer compounds and additives. For example, dry paper strength agents such as starch derivatives, polyacrylamide, polyvinyl alcohol derivatives, gelatin, fatty acid salts, rosin derivatives, sizing agents such as dialkyl ketene dimer emulsions, melamine resins, urea resins, polyamide polyamine epichlorohydrin resins, etc. A wet paper strength enhancer, a stabilizer, a pigment, a dye, a fluorescent brightener, a latex, an inorganic electrolyte, a pH adjuster and the like can be appropriately combined and contained.

The resin capable of forming a film used in the practice of the present invention may be any resin such as polyolefin, polystyrene, polyvinyl chloride, etc., as long as it can be melt-extruded, and is not particularly limited. This is particularly advantageous in terms of good adhesion to the base paper, cost, and the like.
The polyolefin resin referred to in the present invention is a low-density polyethylene, a medium-density polyethylene, a high-density polyethylene, a homopolymer of an olefin such as polypropylene, polybutene, or polypentene, or a copolymer comprising two or more olefins such as an ethylene-propylene copolymer. It is a coalescence and a mixture thereof, and various densities and melt viscosity indices (hereinafter, abbreviated as MI) are used alone or in combination.

[0023] in a resin with film forming properties for use in the practice of the present invention, titanium oxide, zinc oxide, talc, white pigments, stearic acid amide, such as calcium carbonate, fatty acid amides, such as arachidic acid amide, stearate zinc, Fatty acid metals such as calcium stearate, aluminum stearate, magnesium stearate, zirconium octylate, sodium palmitate, calcium palmitate, sodium laurate, tetrakis [methylene-3 (3,5-di-tert-butyl-4-hydroxy) Phenyl) propionate] methane, 2,6-di-
antioxidants such as tert-butyl-4-methylphenol; blue pigments and dyes such as cobalt blue, ultramarine, cerulean blue, and phthalocyanine blue; magenta pigments and dyes such as cobalt violet, fast violet, and manganese purple; Optical brighteners such as butylbenzoxazole) thiophene and bis (methylbenzoxazole) naphthalene, tinuvin 320,
It is preferable to add various additives such as ultraviolet absorbers such as tinuvin 326 and tinuvin 328 (trade names of Ciba-Geigy) in appropriate combination.

As a method for adding these additives to a resin, preferably a polyolefin resin, a melt-mixing method using a heating kneading roll, a Banbury mixer, a kneader, a kneading extruder or the like is most suitable. Alternatively, a compound containing only a desired composition ratio may be prepared and used, or a master batch containing each component at a high concentration may be prepared for each component, and then mixed at a desired ratio. Good.

The resin-coated paper used in the practice of the present invention is
It is manufactured by a so-called extrusion coating method in which a heated and melted resin is cast on a normally running base paper, and preferably both surfaces are coated with the resin. In addition, before coating with resin, corona discharge treatment, flame treatment, etc.
It is preferable to perform an activation treatment. The emulsion side surface of the resin-coated paper has a glossy surface, a matte surface, a silk surface, etc., depending on the application, the back surface is usually a matte surface, and the corona surface is Activation treatment such as discharge treatment and flame treatment can be performed,
Further, an undercoat layer mainly composed of a hydrophilic resin such as gelatin may be provided. The thickness of the resin layer of the resin-coated paper is not limited, but generally, it is preferably extruded and coated to a thickness of about 5 μm to 30 μm.

The photographic support of the present invention is provided with various photographic constituent layers to provide color photographic printing paper, reversal color photographic printing paper, black-and-white photographic printing paper, photolithographic printing paper, and computerized photolithographic printing paper. It can be used for various purposes, such as for printing paper, copy paper, reversal photographic material, silver salt diffusion transfer method negative and positive, and printing material.

For example, a silver chloride, silver bromide, silver chlorobromide, silver iodobromide, silver chloroiodobromide emulsion layer can be provided. The silver halide photographic emulsion layer may contain a color coupler to provide a multilayer silver halide constituting layer. Further, a silver salt diffusion transfer image-receiving layer can be provided by incorporating a physical development nucleus. As binders for these photographic constituent layers, hydrophilic polymers such as polyvinylpyrrolidone, polyvinyl alcohol and polysaccharide sulfate compounds can be used in addition to ordinary gelatin.

Further, the above-mentioned photographic constituent layer can contain various additives. As example sensitizing dyes, cyanine dyes, merocyanine dyes, as chemical sensitizers,
Water-soluble gold compounds, sulfur compounds, etc., as antifoggants or stabilizers, hydroxytriazolopyrimidine compounds, mercapto-heterocyclic compounds, etc., as hardeners, formalin, vinylsulfone compounds, aziridine compounds, etc., as coating aids, Benzene sulfonate, sulfosuccinate salt, etc., anti-staining agents such as dialkyl hydroquinone compounds, etc., as well as fluorescent brighteners, sharpness improving dyes, antistatic agents, pH regulators, fogging agents, and silver halide At the time of dispersion, a water-soluble iridium, a water-soluble rhodium compound and the like can be appropriately combined and contained.

The silver halide photographic material according to the present invention comprises:
In accordance with the photographic material, processing such as exposure, development, stop, fixing, bleaching, and stabilization as described in “Photosensitive Materials and Handling Methods” (Kyoritsu Shuppan, Goro Miyamoto, Photographic Technology Course 2) is performed. Will be

[0030]

Next, the present invention will be described in more detail with reference to examples. 1) Production of Photographic Support The back surface of a running base paper having a basis weight of 80 g / m ² was subjected to a corona treatment to obtain a low-density polyethylene (density 0.920; MI4.
0) 50 parts by weight, high density polyethylene (density 0.96
0; MI 7.0) 16 parts by weight of the resin composition
Melt extrusion coating was performed at 300 ° C. with a coating amount of g / m ² . Next, the surface is subjected to corona treatment, and 30 parts by weight of a master batch composed of 50 parts by weight of low-density polyethylene (density 0.918; MI 9.0) and 50 parts by weight of rutile-type titanium dioxide;
Low-density polyethylene (density 0.918; MI 5.0) 7
The resin composition consisting of 0 parts by weight was melt-extruded and applied at 300 ° C. at a coating amount of 14 g / m ² .

Next, after the back resin surface is subjected to corona treatment, the following back coat liquid is supplied by a gravure roll coater, and a wet bar is applied using a wire bar having a wet coating amount of 10 g / m ² .
The coating amount was adjusted and dried with a hot air tunnel dryer at an air temperature of 130 ° C. The drying time was about 5 seconds. Next, a corona treatment was applied to the surface resin surface, and a 1% aqueous gelatin solution was applied with an air knife coater at a wet application amount of 5 g / m ² , dried, and wound up.

Example 1 20 parts by weight of enzyme gelatin (viscosity of 1.2 cPs by the PAGI method; sample name: P-3226) 5 parts by weight of silica fine powder (Syloid 79) 3.75% by weight of 2-ethylhexyl sodium sulfosuccinate 0.73 part by weight 2,4-Dichloro-6-human peroxy-1,3,5-triazine sodium salt 10% solution 14.3 parts by weight (to 100 parts by weight with water)

Examples 2 and 3 Enzyme gelatin (PAGI method viscosity: 1.4 cPs: sample name: P-3308), (PAGI method viscosity: 1.7 cPs)
Samples similar to Example 1 except that the sample name P-3225) was used were referred to as Examples 2 and 3.

Comparative Example 4 A sample prepared in the same manner as in Example 1 except that the concentration of the back coat coating solution was reduced to 1/3, was designated as Comparative Example 4.

Comparative Example 5 The same procedure as in Example 1 was carried out except that enzyme gelatin (PAGI method viscosity: 2.2 cPs: sample name: P-3240) was used as the back coat gelatin. However, the coating amount could not be controlled, and the coating amount was excessive, resulting in drying. Was inadequate. Further, the coated surface had many streaks and was uneven. An attempt was made to change the application method by changing the air knife and blade, but it was not possible to control the amount of application and the surface quality of the application. The gelatin used for the above back coat was manufactured by Nitta Gelatin Co., Ltd.

Comparative Example 6 The gelatin of the back coat was replaced with an alkali-treated gelatin (PA
Using GI method viscosity 6.2cPs: IK-4000 (manufactured by Nippi Corporation)
A sample of Comparative Example 6 was prepared by reducing the concentration to 1/3 as a whole.

Comparative Example 7 Back coating was performed on a separate line, and the coating liquid of Comparative Example 6 was applied to 3
A sample of Comparative Example 7 was prepared by increasing the drying conditions at an application amount of 0 g / m ² .

2) Preparation of photographic paper The surface of each of Examples 1, 2, and 3 and Comparative Examples 4, 6, and 7 was 1.35 g / m ^{2 of} silver bromide, 3.0 g / m ² of gelatin, and 1 An emulsion layer consisting of a hardening agent of 0.5% by weight of gelatin and a coating aid, a protective layer consisting of a hardening agent of gelatin at 1.2 g / m ² , 1.8% by weight of gelatin and a coating aid, Apply to photographic paper 1,2,3,4
6,7 were obtained.

3) Evaluation method (curl degree measurement at each humidity)
The sample is cut to 50 mm in the horizontal direction (curl in the horizontal direction) × 100 mm in the winding direction (MD = curl in the vertical direction), and further cut to a width of 50 mm × length of 3 mm perpendicular to the center line. This sample was allowed to stand for 20 hours in an atmosphere of 25 ° C., 20, 55, and 80% RH, and the curl material was placed on a horizontal table with the convex portion facing down, and the distance between both ends and the table was measured. The curl which makes concave is plus, and the curl which makes convex is minus.

The results are shown in Table 1. In Examples 1, 2, 3, and Comparative Example 4, both the coating amount control and the drying were good, but in Comparative Example 5, there was a problem in the coating amount control, and the drying was insufficient. Also, the surface quality was not good. Examples 1, 2, and 3 show good curl suppression similarly to Comparative Example 7, which was separately prepared, whereas Comparative Examples 4 and 6 show large curl fluctuations with changes in humidity.

[0041]

[Table 1]

[0042]

According to the present invention, since a back coat layer having a sufficient coating amount for curl suppression is provided by a coating apparatus provided on a resin-coated paper manufacturing apparatus, it is inexpensive and has no danger of surface contamination. A photographic support with curling prevention can be obtained.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-62-49347 (JP, A) JP-A-63-25649 (JP, A) JP-A-2-87138 (JP, A) JP-A-3- 282537 (JP, A) JP-A-52-115214 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03C 1/76 502 G03C 1/81

Claims (2)

(57) [Claims] 1. A resin-coated paper-type photographic support having paper as a base material and coated on both sides with a resin capable of forming a film, a hydrophilic back coat on a side opposite to a side on which a photographic image is formed. And the binder of the back coat layer is PAG
The viscosity η determined by the method I is 1.2 cPs to 2.0 cPs ,
The peak value of the molecular weight distribution is 8,000 to 20,000,
Average molecular weight of <br/> gelatin in the range of 17,000 to 60,000, and the coating amount of gelatin contained in the back coat dry weight 0.7g / m ² ~5.0g / m ² A photographic support characterized in that: 2. The photographic support according to claim 1, wherein the gelatin is an enzyme-treated gelatin.