JPH0652390B2 - Support for photographic paper - Google Patents

Description

TECHNICAL FIELD The present invention relates to a support for photographic printing paper. More specifically, the present invention provides a photographic paper support useful for producing a photographic paper which, after being developed and dried, exhibits excellent separation workability in the obtained photograph. It is about the body.

[Conventional technology]

Conventionally, baryta paper has been used as a support for photographic printing paper, but in recent years, a water-resistant support in which a coating layer made of a polyolefin resin is provided on both surfaces of a base made of paper has come to be used. This coating layer has the advantages of shortening the washing and drying times during development of the resulting water-resistant support, keeping its rigidity and various strengths at a high level, and reducing stains due to chemical penetration. ing.

As the sheet material forming the base of the support, paper made of high-purity, high-whiteness pulp which is substantially free of impurities is used. Further, in order to prevent stains from being produced on the product due to the permeation of the chemical liquid from the edge portion of the paper base, the paper base is subjected to a strong size treatment, a rigidity increasing treatment, an antistatic treatment and the like.

In addition, the polyolefin resin coating layer forming the surface of the support to be coated with the photographic emulsion (hereinafter referred to as the surface of the support) has good photographic suitability such as whiteness, opacity and fog prevention. , Titanium oxide, colored pigments, fluorescent brightening agents, antioxidants, antifoggants, and various other additives are kneaded.

Further, the polyolefin resin coating layer formed on the surface of the support opposite to the surface to be coated with the photographic emulsion (hereinafter referred to as the back surface of the support) has a polyolefin used on the front surface side of the support as a curl prevention measure for printing paper. A polyolefin resin having a density slightly higher than that of the resin is used. Also,
The polyolefin resin coating layer is provided with an appropriate matte finish for making it like paper.

Recently, with the increase in cutting speed of photographic printing paper in a color photographic laboratory, various troubles due to static electricity often occur during the handling of photographic printing paper manufactured using the water-resistant support as described above. It became so.

This problem is that the photographic printing paper is charged with static electricity during its handling and adsorbs dust, dust, etc.
In some cases, various spots such as desensitization and fog properties are caused, and accumulated static electricity may cause fog.

Furthermore, after the printed printing paper is developed and treated with a chemical solution such as bleach-fixing, the obtained photographs are cut and stacked.
Also in this case, it was difficult to orderly stack the photos due to the generation of static electricity, and when separating the photos one by one, it was difficult to separate the photos by sticking them together, and it was difficult to handle them.

Various proposals have been made to solve the above problems. For example, as described in JP-B-57-53940, US.PAT 3033679, and US.PAT 3437484, an attempt has been made to apply an antistatic treatment by applying a conductive agent to the back surface of the support. However, although these attempts are effective in preventing the electrification of the photographic paper before the development treatment, the conductivity is lost by the chemical treatment such as development and bleach-fixing. There was little effect in solving problems in handling photographic paper after the treatment.

[Problems to be Solved by the Present Invention]

The present invention is intended to provide a photographic printing paper support useful for solving the drawbacks of conventional photographic printing papers, that is, the defective separation (separation) of the photographic printing papers after development processing.

[Means for Solving the Problems]

The support for photographic printing paper of the present invention is formed on a substrate made of a sheet material, a front surface coating layer and a back surface coating layer formed of a polyolefin resin material on both front and back surfaces of the substrate, and the back surface coating layer. And a back surface antistatic layer, wherein the back surface antistatic layer is a matrix-forming resin material,
An antistatic agent and a static friction modifier, wherein the antistatic agent is polystyrenesulfonic acid, polyvinylsulfonic acid, polyacrylic acid, polymethacrylic acid, salts of the above acids, and an average addition mole of ethylene oxide per glucose unit. At least 1 selected from hydroxyethyl cellulose having a number (average number of moles of substitution) of 2.0 to 2.8
The static friction modifier is colloidal silica, silicon dioxide,
It comprises at least one selected from calcium carbonate, magnesium carbonate, titanium oxide, aluminum oxide, and barium sulfate, and the back surface antistatic layer has a surface electric resistance of 1 after development.
Or less × 10 ¹³ Omega, and said back surface antistatic layer, static friction coefficient between the photographic emulsion layer to be formed on the surface coating layer is 0.55 or less, it is characterized in.

That is, the present inventors have conducted intensive studies to eliminate the above-mentioned drawbacks of the conventional photographic printing paper support, and as a result, provide a backside antistatic layer on the backside coating layer of the support,
This backside antistatic layer contains an antistatic agent and a static friction modifier made of a specific material together with the matrix-forming resin material to adjust the electric resistance of the backside of the photographic paper after development to 1 × 10 ¹³ Ω or less. Further, it was found that when the coefficient of static friction between the back surface of the printing paper and the emulsion layer is adjusted to 0.55 or less, the sliding property of the printing paper is improved and the judgment property is improved, and the present invention has been completed based on this discovery.

That is, the sizing property of photographic paper is determined by two factors, the first of which is the adhesion between photographic paper pieces due to static electricity, and the second of which is the slipperiness or static friction of the emulsion layer and the back surface of the photographic paper. Is. In order to prevent adhesion due to static electricity, it is effective to keep the surface electric resistance after development low. If the surface electric resistance after development is 1 × 10 ¹³ Ω or less, the mutual photographic paper pieces due to static electricity Adhesion can be prevented.
However, the prevention of electrostatic contact of the photographic paper does not improve the mutual resistance of the photographic paper pieces or the photographic pieces, and the electric resistance of the back surface of the photographic paper after the development processing is adjusted to 1 × 10 ¹³ Ω or less, and further, The coefficient of static friction between the emulsion layer and the back of the photographic paper is 0.55.
The following adjustments are necessary.

On the other hand, even if the coefficient of static friction is 0.55 or less, if the electric resistance of the back surface of the printing paper after the development processing is larger than 1 × 10 ¹³ Ω, the printing paper is adhered to the static electricity, and the sagability is not good.

The sheet material constituting the substrate used for the support of the present invention may be one generally used for a photographic printing paper support, for example, natural pulp paper, synthetic pulp paper, mixed pulp of natural pulp and synthetic pulp. In addition to the above, various types of laminated paper can be used. It is possible to add additives such as a sizing agent, a fixing agent, a paper-strengthening agent, a filler, an antistatic agent, and a dye, which are generally used for papermaking, to this base paper,
Further, a surface sizing agent, a surface strength agent, an antistatic agent, etc. can be appropriately applied on the surface.

The polyolefin resin used for coating both sides of the paper substrate can be selected from α-olefin homopolymers such as polyethylene and polypropylene, α-olefin copolymers, and mixtures of these various polymers. . Particularly preferred polyolefin resins are low density polyethylene, high density polyethylene and mixtures thereof. Although the molecular weight of the polyolefin resin is not particularly limited, it is usually in the range of 20,000 to 200,000.

It is already known to add various additives such as a white pigment, a colored pigment, a fluorescent whitening agent, and an antioxidant to a polyolefin resin, and in the present invention, the surface coated with a photographic emulsion is formed. It does not matter at all if these additives are added to the polyolefin layer.

In the present invention, an antistatic layer is formed on the back surface polyolefin resin coating layer. This antistatic layer contains a matrix-forming resin material, an antistatic agent, and a static friction modifier.

Matrix-forming resin materials include styrene-butadiene copolymer latex, vinyl acetate polymer latex,
It is preferable to use at least one selected from acrylic polymer-based latex, acrylonitrile-butadiene copolymer-based latex, and water-soluble polymer compound.

As a styrene-butadiene copolymer latex,
Examples thereof include styrene / butadiene copolymer latex and carboxy-modified styrene / butadiene copolymer latex.

Examples of the vinyl acetate polymer-based latex include latex such as polyvinyl acetate, vinyl acetate-acrylic acid ester copolymer, and vinyl acetate-ethylene copolymer.

As the acrylic polymer latex, acrylates such as methyl acrylate, butyl acrylate, 2-ethylhexyl acrylate and methyl methacrylate,
Homopolymers of methacrylic acid esters such as butyl methacrylic acid or polyacrylic latex which is a copolymer emulsion thereof and ethylenically unsaturated copolymerizable monomers copolymerizable with acrylic acid esters and methacrylic acid esters Examples thereof include copolymer emulsions such as methyl methacrylate / butadiene copolymer latex, and carboxy-modified latex thereof such as carboxy-modified polyacrylic latex.

As the acrylonitrile / butadiene copolymer latex, there are latexes such as acrylonitrile / butadiene copolymer and carboxy-modified acrylonitrile / butadiene copolymer, and as the water-soluble polymer compound, water-soluble polyester, acrylic resin, Examples thereof include polyvinyl alcohol, starch, casein, gelatin and the like.

As the antistatic agent, polystyrene sulfonic acid, polyvinyl sulfonic acid, polyacrylic acid, polymethacrylic acid,
Salts of the above acids, such as sodium salt, potassium salt, and ammonium salt, and the average number of moles of ethylene oxide added per glucose unit (average number of substitution moles).
Is at least one selected from 2.0 to 2.8 hydroxyethyl cellulose.

The antistatic agent is preferably contained in the backside antistatic layer in an amount of 1 to 20% by weight.

The static friction modifier is at least one selected from colloidal silica, silicon dioxide, calcium carbonate, magnesium carbonate, titanium oxide, aluminum oxide, and barium sulfate.

The static friction modifier is preferably contained in the backside antistatic layer in an amount of 10 to 80% by weight.

Generally, the backside antistatic layer is preferably formed on the backside polyolefin resin coating layer at a weight of 0.05 to 1.0 g / m ² (dry weight).

Conventional methods can be used to produce the photographic paper support of the present invention.

In particular, when laminating the back surface polyolefin resin coating layer on the back surface of the sheet-shaped substrate, it is preferable to form a mat-like shape with a cooling roll.

In addition, it is preferable that the surface of the back surface polyolefin resin coating layer has its adhesiveness improved by, for example, corona discharge treatment, and then the back surface antistatic layer is formed. At this time, an adhesive may be used.

〔Example〕

The present invention will be described more specifically with reference to the following examples and comparative examples.

Examples 1-3 and Comparative Examples 1-4 In each of Examples 1-3 and Comparative Examples 1-4, basis weight
The surface of a 175 g / m ² base paper is coated with 30 g / m ^{2 of} polyethylene (d = 0.94, MI = 6.8) containing 10% by weight of titanium dioxide, and the back surface of the same resin is the cooling roll shown in Table 1. Was pressed at 20 ° C. and 20 kg / cm to coat a backside polyethylene coating layer of 30 g / m ² , and the backside polyethylene coating layer was subjected to corona discharge treatment. Next, a back coating liquid having the composition shown in Table 1 was applied onto the back polyethylene coating layer by bar coating to give a dry weight of 0.5 g / m 2, respectively.
^It was coated so as to be ² and dried at a drying temperature of 80 ° C. for a drying time of 60 seconds to form a backside antistatic layer. A silver halide photographic emulsion having the following composition was coated on the surface polyethylene coating layer of the photographic paper support thus obtained so that the dry weight was 10 g / m ² , and dried to form a photographic emulsion layer. , Got a photographic paper.

Silver halide photographic emulsion composition Silver halide emulsion ^Note) (Contains 80 g of gelatin and 16 g of silver) 1 kg Formalin (20% aqueous solution) 3 ml Saponin (10% aqueous solution) 20 ml Add water to a total amount of 1.5 kg Note) Silver chloride 40 mol %, And silver chlorobromide emulsion consisting of 60 mol% of silver bromide. The static friction coefficient, surface resistance after development processing, and discriminating property of each sample were evaluated by the following methods.

(1) Static friction coefficient: − J.TAPPi paper pulp test method No. 30 (friction coefficient test method for paper and board [horizontal method]) was used to measure the static friction coefficient between the backside antistatic layer and the surface emulsion layer of photographic paper. . However, the moving speed was 100 mm / min.

(2) Surface electric resistance after development treatment: -The sample was passed through an automatic processor (Durst RCP20 (trade name): made by Durst) containing a developer and a bleach-fixing solution, washed with water for 1 minute, and then dried. (Dust FRC400 (trade name): manufactured by the same company)
And dried at 90 ° C. for 5 minutes. This test piece is then
Conditioned under constant temperature and humidity of ℃, 65% RH for 20 hours.
y cell (Model 16008 A (trade name): YOKOGAWA-HEWLETT P
The surface electric resistance value was calculated by reading the value for 1 minute from the start of energization with a meter (4329 A (trade name): manufactured by Dojo Co., Ltd.).

(3) Separability 1000 sheets of 80mm x 115mm sample that have been developed and dried with an automatic processor are piled up, and when picking up one sample from the top sample with one hand, the number of times two or more sheets stick together Was evaluated, and ranked into 5 grades according to the following classifications, and judged as the judgment property.

5 points: 0 to 2 times 4 points: 2 to 4 times 3 points: 5 to 10 times 2 points: 10 to 20 times 1 point: 20 times or more Among the above, a practical judgment property is 4 points or more did.

The photographic papers of Examples 1 to 3 within the scope of the present invention all showed good handling property, but the photographic papers of Comparative Examples 1 to 4 were unsatisfactory in at least one of static friction coefficient and surface electric resistance after development. Was shown, and these judgment properties were all unsatisfactory.

〔The invention's effect〕

As is clear from the above description, particularly Table 1, the photographic paper support of the present invention has a backside antistatic layer of a special composition formed on the backside polyolefin resin coating layer, and is obtained by this. Surface electrical resistance after development of photographic paper is 1
It is possible to control the static friction coefficient of the backside antistatic layer and the emulsion layer to be 0.55 or less, and to be 10 ¹³ Ω or less,
Further, the handling property was remarkably improved.

Claims (6)

[Claims] 1. A substrate made of a sheet material, a front surface coating layer and a back surface coating layer formed of a polyolefin resin material on both front and back surfaces of the substrate, and a back surface antistatic layer formed on the back surface coating layer. And a back surface antistatic layer, a matrix-forming resin material,
An antistatic agent and a static friction modifier, wherein the antistatic agent is polystyrenesulfonic acid, polyvinylsulfonic acid, polyacrylic acid, polymethacrylic acid, salts of the above acids, and an average addition mole of ethylene oxide per glucose unit. At least 1 selected from hydroxyethyl cellulose having a number (average number of moles of substitution) of 2.0 to 2.8
The static friction modifier is colloidal silica, silicon dioxide,
It comprises at least one selected from calcium carbonate, magnesium carbonate, titanium oxide, aluminum oxide, and barium sulfate, and the back surface antistatic layer has a surface electric resistance of 1 after development.
× 10 ¹³ Ω or less, and the coefficient of static friction between the backside antistatic layer and the photographic emulsion layer to be formed on the surface coating layer is 0.55 or less, a photographic paper support . 2. The support according to claim 1, wherein the back surface coating layer is matt-treated. 3. The support according to claim 1, wherein the content of the antistatic agent in the backside antistatic layer is in the range of 1 to 20% by weight. 4. The support according to claim 1, wherein the content of the static friction modifier in the backside antistatic layer is in the range of 10 to 80% by weight. 5. The matrix resin material of the backside antistatic layer is a styrene / butadiene copolymer latex, a vinyl acetate polymer latex, an acrylic polymer latex, an acrylonitrile / butadiene copolymer latex, and a water-soluble polymer compound. The support according to claim 1, comprising at least one selected from the group consisting of: 6. The support according to claim 1, wherein the backside antistatic layer has a weight of 0.05 to 1.0 g / m ² .