JPS5880637A - Support for photographic paper - Google Patents

Abstract

PURPOSE:To prevent the edge stain of photographic paper due to the penetration of a processing soln. from the edges by using a mixture of modified polyvinyl alcohol with a metallic salt for the base paper. CONSTITUTION:The base paper of a support for photographic paper consisting of the base paper and polyolefin coating layers at least one of which contains a white pigment on both sides of the base paper is impregnated or coated with a nixture of 100pts.wt. carboxyl modified polyvinyl alcohol with 5-200pts.wt. bivalent metallic salt so as to adjust the amount of the modified polyvinyl alcohol to >=0.5g/m<2>. The bivalent metallic salt is halide, sulfate or other slat of Ca, Mg, Zn, Ni or other bivalent metal. When the amount is <0.5g/m<2>, the surface strength of the base paper is not increased.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a waterproof support for photographic paper, and more particularly to a support for photographic paper comprising a base paper and a polyolefin coating layer provided on both sides of the base paper. The present invention relates to a support for photographic paper that is capable of preventing the occurrence of edge stains due to infiltration of a developing treatment solution from the cut surfaces of the ends of photographic paper formed from the support.

For photographic light-sensitive materials that use paper as a support, especially photographic paper, research has been carried out to make the support waterproof paper for the purpose of speeding up the development process. Coated, waterproof supports for photographic paper have been developed.

A waterproof support for photographic paper is composed of a base paper and a polyolefin coating layer provided on both sides of the base paper.
The polyolefin coating layer on the front side, that is, the side on which the photographic emulsion coating layer is provided, contains a white pigment for the purpose of increasing the sharpness of the image.

A support for photographic paper is provided with a photographic emulsion layer on its front side and used as photographic paper. After a negative image is printed on the photographic paper, it is processed with a developing solution (hereinafter simply referred to as "developing solution") to produce a photograph with a positive image.

When developing photographic paper, both surfaces of the photographic paper support are highly waterproof, but on the other hand, there is a tendency for the developer to seep in through the cut edges of the photographic paper. There is a problem in that edge stains are likely to occur. This edge stain occurs when the developer penetrates from the edge of the photographic paper to a distance of 0.
If it exceeds 2 mm, it becomes noticeable through the polyolefin coating layer and the photographic emulsion layer, leading to a decrease in photographic value, so improvements are desired.

In order to prevent this edge staining, attempts have been made to, for example, give the base paper of the support a sophisticated size;
The results cannot be said to be satisfactory.

In addition, a method of applying a water repellent to the edge of photographic paper (for example, disclosed in JP-A-53-110819) or a method of applying carboxyl-modified polyvinyl alcohol (for example, disclosed in JP-A-53-14235) ) have also been proposed, but these methods do not yield fully satisfactory results.

SUMMARY OF THE INVENTION An object of the present invention is to provide a support for photographic paper that can effectively prevent edge staining of photographic paper due to developer.

As a result of various studies based on the above object, the present inventors have discovered a method for surface treatment using a specific ratio of carboxyl-modified polyvinyl alcohol containing maleic acid or itaconic acid as a copolymerization component and a divalent metal salt. A solution of the mixture was applied to the base paper of the support for photographic paper, and the carboxyl-modified polyvinylalconocarbonate was applied to the base paper of the support for photographic paper. By impregnating or coating the paper to a certain amount or more, it is possible to significantly reduce edge stains without causing any negative photographic effects on the photographic paper. The present invention has been achieved based on the discovery that the surface strength of the material can also be improved.

Accordingly, the present invention provides a support for photographic paper comprising a base paper and a polyolefin coating layer provided on both sides of the base paper, and at least one of the polyolefin coating layers is a polyolefin coating layer containing a white pigment. Alternatively, an FF product consisting of 100 parts by weight of carboxyl-modified polyvinyl alcohol containing itaconic acid as a copolymerization component and 5 to 200 parts by weight of a divalent metal salt is applied to base paper so that the amount of impregnation or coating of the carboxyl-modified polyvinyl alcohol is 0. The present invention provides a support for photographic paper, characterized in that it is impregnated or coated to have a weight of at least .5 g/m'.

Next, the present invention will be explained in detail.

The photographic paper support of the present invention has a basic structure consisting of a base paper and a polyolefin resin coating layer provided on both sides of the base paper.

The base paper is selected from materials commonly used for photographic paper. Examples of such materials include natural pulp paper, synthetic pulp paper, paper made from a mixture of natural pulp and synthetic pulp, and various types of paper stock.

Base paper is typically used in thicknesses of 30-500 microns.

In the present invention, base paper is impregnated or coated with a mixture of 100 parts by weight of carboxyl-modified polyvinyl alcohol containing maleic acid or itaconic acid as a copolymerization component and 5 to 20 parts by weight of a divalent metal salt, for example, as an aqueous solution. .

The carboxyl-modified polyvinyl alcohol containing maleic acid or itaconic acid as a copolymerization component used in the present invention preferably has a degree of saponification of 90-1118% and a carboxyl group content of 1-20 mol%, and is preferably 5% by weight. Preferred are those exhibiting a viscosity in the range of about 5-100 cps when measured as an aqueous solution.

The degree of polymerization is preferably about 1000-3000, and more preferably about 1800-1800.

Carboxyl-modified polyvinyl alcohol containing maleic acid or itaconic acid as a copolymerization component as described above is generally prepared by (1) saponifying a copolymer of maleic acid or itaconic acid and a vinyl monomer, or (2)
It is produced by modifying polyvinyl alcohol with maleic acid or itaconic acid.

The method (1) of saponifying a copolymer of maleic acid or itaconic acid with a vinyl monomer is an ester of a lower carboxylic acid with a vinyl alcohol such as vinyl acetate, vinyl formate, vinyl chloride, or vinyl robionate, and anhydride. This method is typified by the method of saponifying a copolymer consisting of ÷leic acid, itaconic acid, or maleic acid ester. As the vinyl hexamer, other types of vinyl compounds such as acrylamide, methacrylamide, methylolacrylamide, etc. can also be used instead of the ester of vinyl alcohol and lower carboxylic acid.

In the method (2) of modifying polyvinyl alcohol with maleic acid or itaconic acid, polyvinyl alcohol containing maleic acid or itaconic acid as a copolymerization component is modified with a polyhydric carboxylic acid such as maleic acid or itaconic acid, or an anhydride thereof. It is manufactured by introducing carboxyl groups into the copolymer through esterification.

Preferred examples of divalent metal salts used in the present invention include alkaline earth metals such as calcium and magnesium or transition metals such as zinc as cations, while halogen elements such as chlorine or Examples include salts having anion such as sulfate ion.

However, the metal salts are not limited to these salts, but particularly preferred metal salts are calcium chloride and magnesium chloride.

In the present invention, a mixture is prepared by adding a divalent metal salt in an amount within the range of 5 to 200 parts by weight to 100 parts by weight of carboxyl-modified polyvinyl alcohol containing maleic acid or itaconic acid as a copolymerization component. and use it as a mixture for surface treatment. If the amount of metal salt is less than 5 parts by weight, it is not suitable for the present invention because it is difficult to effectively reduce edge stains on the resulting photographic paper. Also, the amount of metal salt is 2
If it exceeds 0.00 parts by weight, no improvement in the surface strength of the base paper will be observed, which is not preferable.

The surface treatment mixture of the present invention is usually prepared as an aqueous solution and impregnated or applied onto base paper. This surface treatment mixture aqueous solution contains an antistatic agent (for example, 1. Inorganic salts such as sodium sulfate and potassium chloride or a surfactant),
Fluorescent dye 1. Additives such as antifoaming agents may also be added. Moreover, these additives can also be applied or impregnated onto the base paper separately from the above-mentioned aqueous solution of the surface treatment mixture.

The surface treatment mixture of the present invention contains at least Q, 5 g/m' of carboxyl-modified polyvinyl alcohol containing maleic acid or itaconic acid as a copolymerization component, based on the base paper.
It is necessary to impregnate or apply it so that it becomes . If the amount of impregnation or application is less than 0.5 g/ml, the surface strength of the base paper will not be sufficiently improved, which is not preferable. It is preferable to use the on-machine size press method or the on-machine tab size method as a method for impregnating or coating the base paper with the aqueous solution of the surface treatment mixture. However, in the off-machine method, bar,
Coating may be performed using gravure, air knife, or the like.

The base paper for a photographic paper support impregnated or coated with the surface treatment mixture of the present invention by the method described above is then provided with a polyolefin coating layer by a known method.

Examples of the polyolefin used in the polyolefin coating layer include homopolymers of α-olefins such as polyethylene and polypropylene, copolymers of these α-olefins, and mixtures of these various polymers. A particularly preferred polyolefin is polyethylene. There is no particular restriction on the molecular weight of these polyolefins as long as extrusion coating is possible, but polyolefins having a molecular weight in the range of 20.000 to 200.000 are usually used. The thickness of the polyolefin resin coating layer is not particularly limited and can be determined according to the thickness of the coating layer of polyolefin resin coated paper for conventional photographic paper supports. is 10-1
00 microns, and especially from the range of 15-50 microns.

It is already known that various additives such as white pigments, colored pigments, optical brighteners, and antioxidants are added to the polyolefin resin used to form the resin coating layer of polyolefin resin-coated base paper for photographic paper. Therefore, it is naturally possible to add such various additives in preparing the polyolefin resin of the present invention, and it is preferable depending on the purpose. Regarding the types, amounts, and methods of adding such various additives, see, for example, U.S. Patent No. 3,83
3.31110, No. 4,189,188, No. 3,5
No. 01,298, No. 3.449,257, No. 3,49
It is described in detail in publications such as No. 9,782. Alternatively, the additives can be applied onto the coating layer after it is formed, as described in U.S. Pat. No. 3,884.892. Alternatively, a resin coating layer, as described in publications such as U.S. Patent No. 2,715,075; A surface activation treatment can also be performed as necessary.

In order to prepare photographic paper by coating the photographic paper support of the present invention with a photographic emulsion, methods conventionally used for manufacturing photographic paper can be used. In addition, conventionally used techniques can be used for processing such as developing and fixing the photographic paper manufactured in this way. Regarding these conventional techniques, for example, Makoto Kikuchi: Photo Chemistry (Kyoritsu Shuppan: 1973), and C, E.
Mess r THE THEORY OF TH
E PH0TOGRAPHIC: PROCESS
It is described in detail in J 3rd, ed, lt.

Next, Examples and Comparative Examples of the present invention will be described.

[Example 1-3 and Comparative Example 1-3] (1) Preparation of sample Wood hull/1&a (LBKP/NBKP = 1/
1) Cold water solutions containing sodium stearate, sodium stearate, and aluminum sulfate were added to the pulp slurry obtained by complete beating at a ratio of 5 parts by weight and 10 parts by weight, respectively, based on 100 parts by weight of bone-dry wood pulp. This pulp slurry was used to make paper with a basis weight of 180 g/m'' to prepare a base paper for a photographic paper support.

Separately, carboxyl-modified polyvinyl alcohol (PVA; degree of saponification 88%; copolymerized with maleic anhydride;
Carboxyl group content 2 mol%; viscosity of 5 ml aqueous solution 88
cps; degree of polymerization 1800) and 100 parts by weight of calcium chloride in the proportions listed in Table 1' and water to make the total amount 2000 parts by weight. was prepared and applied to the above-mentioned base paper at a coating amount of 26 g/r of carboxyl-modified polyvinyl alcohol containing anhydrous and leic acid as a copolymerization component.
It was coated using a test size press machine (manufactured by Kumagai Riki ■) so that it was rr.

A polyethylene coating layer with a density of about 0.965 g/cm3 is applied to the back side of the base paper that has been surface-treated as described above.
On the other hand, a polyethylene coating layer containing 5 weight 2 titanium oxide and a density of about 1.03 g/c♂ was provided on the surface to a thickness of about 0.035 mm, and a layer for color photography was provided. Photographic paper was manufactured by coating the emulsion.

(2) Evaluation of samples: Evaluation of edge stains on photographic paper was conducted using the following method.

Cut the photographic paper into pieces of 8.25 cm and develop it using a color paper automatic processor (model RPV-409 manufactured by Noritsu Kogyo M■). Measured visually.

The surface strength of the base paper is determined by
Paper wax pick test (TAPPI standard?
-4595uJ5) Measured from d.

The measurement results are shown in Table 1.

Table 1 PVA/chloride Immersion of developer Surface calcium of base paper Entry distance (mm) Strength (A) Example 1 510.25 0°1-142 51
5 0 143 5710,
0 14 Comparative Example 1 075 0.9 82 5
10 1.1 123 5/12
0.1 9 Note) Comparative Example 1 is an experimental result for base paper whose surface was treated only with calcium chloride.

[Example 4-6 and Comparative Example 4-6] Carboxyl-modified polyvinyl alcohol containing maleic anhydride as a copolymerization component and carboxyl-modified polyvinyl alcohol containing itaconic acid as a copolymerization component (PVA, degree of saponification 98%; carboxyl Group content 2 mol%; viscosity of 5z aqueous solution 88c
Samples were prepared and evaluated in the same manner as in Example 1, except that ps; degree of polymerization was 1800).

The measurement results are shown in Table 2.

Table 2 PVA/chloride Immersion in developer Surface calcium of base paper Human distance M (mffl) Strength (A) Example 4 510.25 0.1 145
515 0 14'6 5/
10 0 14 Comparative Example 4 015 0.9 85 5
10 1.0 126 5/12
0.3 9 Note) Comparative Example 6 is a reprint of Comparative Example 1.

[Example 7-9 and Comparative Example 7-9] The base paper was weighed 1
The procedure was the same as in Example 1, except that the paper was made to have a weight of 55 g/m', and the amount of carboxyl-modified polyvinyl alcohol containing maleic anhydride as a copolymerization component was applied to the base paper to be 15 g/m'. Sample preparation and sample evaluation were performed. However, carboxyl-modified polyvinyl alcohol containing maleic anhydride as a copolymerization component (
PVA) has a saponification degree of 84%; carboxyl fund content B mol%; viscosity of 5z aqueous solution 50 cps; polymerization degree 1700
belongs to.

The measurement results are shown in Table 3.

Table 3 PVA/chloride Immersion of developer Surface calcium of base paper Entry distance (am) Strength (^) Example 7 1010.5 0 148
10/10 0 1B9 10/2
0 0 1B Comparative Example 7 0/10 0.9 138
1010 1.0 129 10
/25 0.3 8 Note) Comparative example 7 is
These are the experimental results for base paper whose surface was treated only with calcium chloride.

[Example 10-12 and Comparative Example 1'0-12] None'
Carboxyl-modified polyvinyl alcohol containing hydromaleic acid as a copolymerization component and carboxyl-modified polyvinyl alcohol containing itaconic acid as a copolymerization component (PVA i saponification degree 94%; carboxyl group content 6 mol%; viscosity of 5% aqueous solution 50 cps; Samples were prepared and evaluated in the same manner as in Example 7, except that the degree of polymerization was changed to 1700).

The measurement results are shown in Table 4.

Table 4 PVA/chloride Immersion of developer Surface calcium of base paper Insertion distance (Ilm) Strength (A) Example 10 1010.5 0 1411
10/lo 0 1412
10/20 0 1B Comparative Example 10 0/10 0.8 El
ll 1010 1.0 121
2 10/25 0.8 8 Note) Comparison Example 1O is a reprint of Comparative Example 7.

Claims (1)

[Claims] A photographic paper support consisting of a base paper and a polyolefin coating layer provided on both sides of the base paper, at least one of which is a polyolefin coating layer containing a white pigment, in which maleic acid or itaconic acid is copolymerized. A mixture consisting of 100 parts by weight of carboxyl-modified polyvinyl alcohol and 5-200 parts by weight of a divalent metal salt is applied to the base paper so that the amount of impregnation or application of the carboxyl-modified polyvinyl alcohol is 0.5.
1. A support for photographic paper, characterized in that it is impregnated or coated so that it has a g/m" or more -F.