JPS6234154A - Support for photographic printing paper - Google Patents

Abstract

PURPOSE:To prevent trouble due to occurrence of static electricity without losing the conductivity of a photographic printing paper during processing with the chemical solutions of development and bleach fixing by forming a backing coat containing specified hydroxyethyl cellulose on the reverse side of the support. CONSTITUTION:The backing coat containing hydroxyethyl cellulose having an average number of ethylene oxide added to one glucose unit of 2.2-2.8 on the reverse side of the photographic printing paper having coating layers of a polyolefin resin on both sides of a paper base, thus permitting the conductivity of the photographic printing paper not to be lost by the chemical processing using the developing and bleach-fixing solutions or the like, and trouble due to occurrence of static electricity at the times of stacking and handling and the like after the processing of development and bleach-fixing and the like to be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a support for photographic paper. To explain in more detail, the present invention has conductivity on the surface,
Moreover, the present invention relates to a support for photographic paper that is useful for obtaining photographic paper whose electrical conductivity is not lost during development or the like.

[Conventional technology]

Baryta paper has conventionally been used as a support for photographic paper, but in recent years, water-resistant supports have come to be used, in which a paper base is provided with laminated polyolefin resin layers on both sides. This water-resistant support shortens the washing and drying time at 3Af#, eliminates the need for ferrotypes, reduces chemical consumption, maintains high levels of stiffness and strength, and reduces staining due to chemical penetration. It has the following advantages.

The paper base of the support is high purity and contains virtually no impurities.
A high-whiteness lug is used, and it is also treated with strong size treatment, rigidity enhancement treatment, and antistatic treatment to prevent stains due to chemical penetration from the edges.

In addition, the polyolefin resin coating layer that forms the surface of the support to which the photographic emulsion is applied (hereinafter referred to as the support surface) has the following properties: Various additives such as titanium oxide, colored pigments, fluorescent whitening agents, rR-forming capping agents and anti-capri agents are mixed together.

- the side of the blade support opposite to the side to which the photographic emulsion is to be applied (hereinafter referred to as
This is called the support surface. ) The 7C polyolefin resin coating layer formed on the 7C polyolefin resin coating layer also has a slightly higher density polyolefin resin used on the surface of the support to prevent curling of photographic paper. Lyolefin resin is used. Furthermore, the long side of the support is given a suitable matte finish to give it a paper-like appearance. But 'fJj
The resin of the iB layer and the surface of the oil coating layer were usually not subjected to any treatment.

Recently, as the cutting speed of photographic paper in color photographic processing laboratories has increased, troubles due to the generation of static electricity have started to occur in photographic paper using the above-mentioned water-resistant support.

The problem is that static electricity is absorbed during handling, which causes various spots such as water repellency, desensitization, and capri, and when the accumulated static electricity is discharged. This sometimes caused capri, or static marks, to appear on the emulsion. Furthermore, after chemical processing such as development and bleach-fixing, it is cut.

Although they could be stacked, they were not stacked neatly due to static electricity, and multiple sheets stuck together, making handling inconvenient.

Various proposals have been made to solve the above problems. For example, Special Publication Show-57-53940, US, PAT30336
79, USPAT 3437484, attempts have been made to apply a conductive agent to the back surface of the support to perform antistatic treatment. However, although these attempts are effective in preventing static electricity before the development process, conductivity is lost due to chemical processing such as development and bleach-fixing, and they are not effective in preventing static electricity after processes such as development. This method was completely ineffective in solving problems in handling photographic paper after processing.

[Problems to be solved by the present invention]

The present invention solves the drawbacks of conventional photographic paper, namely the problem of static electricity, and provides a support useful for obtaining photographic paper that does not lose its conductivity through chemical processing such as development and bleach-fixing. This is what I am trying to do.

[Means for solving problems]

The photographic paper support of the present invention has a base made of paper and a coating layer made of a polyolefin resin formed on both sides of the base, the coating layer on the back side of the support. On the surface, a backcoat layer containing hydroxyethyl cellulose with an average number of added moles of ethylene oxide per glucose unit in the range of 2.0 to 2.8% is formed in a dry weight of 0.01 to 5.062%. It is characterized by the presence of

The support of the present invention includes a paper base as described above.

A polyolefin resin coating layer formed on both sides of the
The back side of the support (the side opposite to the side on which the photographic emulsion layer is formed)
and a back coat layer containing droxyethyl cellulose.

The paper substrate used in the support sheet of the present invention can be selected from the base papers generally used for photographic paper supports, such as natural pulp paper, synthetic pulp paper, natural pulp and synthetic pulp paper, In addition to mixed paper, there are various types of mixed paper. This base paper may contain additives such as sizing agents, fixing agents, paper strength enhancers, fillers, antistatic agents, dyes, etc. that are generally used in paper manufacturing, and may also contain surface sizing agents, surface strength agents, etc. , an antistatic agent or the like may be appropriately applied to the surface.

The paper substrate used usually has a weight of 100 to 30,097 m2.

The polyolefin resin used to coat both sides of the paper substrate may be a homopolymer of ethylene, α-olefins, such as propylene, or at least two of the above olefins.
It can be obtained from copolymers of various species, and mixtures of at least two of these various species of oak polymers. Particularly preferred polyolefin resins are low density polyethylene, high density polyethylene, and mixtures thereof. There is no particular restriction on the molecular weight of the polyolefin resin, but it is usually 20.
A value in the range of 000 to 200.000 is used. Each coating layer is generally applied to a paper substrate with a weight of 10 to 40 g/m2.

It is already known to add various additives such as white pigments, colored pigments, fluorescent whitening agents, and antioxidants to the polyolefin resin used for the coating layer.

That is, even in the present invention, these additives may be added to the polyolefin resin coating layer on the surface side of the support to which the photographic emulsion is coated.

On the surface of the polyolefin resin coating layer on the back side of the support,
A sulbak coat layer containing droxyethyl cellulose is formed. At this time, in order to improve the adhesion of the surface of the coating layer to the back coat layer, this surface may be subjected to corona discharge treatment, low temperature plasma treatment, or the like.

The present inventors provided an electrically conductive backcoat layer on the back side of a support for photographic paper, and investigated various means for preventing the problems caused by the generation of static electricity as described above. In particular, we investigated ways to maintain electrical conductivity even after processing photographic paper with chemicals such as developer and bleach-fix solution.

The average number of moles of ethylene oxide added (average number of moles substituted) per glucose unit as a conductive agent is 2.0 to 2.8.
It has been found that the above object can be achieved by using hydroxyethyl cellulose of

Conventionally commonly used sodium chloride, potassium chloride, calcium chloride, magnesium chloride, sulfuric acid)
IJum, other inorganic salts, and cationic conductive agents such as quaternary ammonium salts, amide-type cations, alkylamine derivatives, tertiary amines, fatty acid amide rust conductors, alkali IJti of polyacrylic acid, and polystyrene sulfonic acid. A back coat layer imparted with electrical conductivity using an anionic conductive agent such as an alkali salt can provide sufficient electrical conductivity before the photographic paper is developed. However, the electrical conductivity of the photographic paper cannot be maintained after these treatments because the electrically conductive components mentioned above are eluted into the chemical solution during processing with a developer, bleach-fix solution, or the like.

However, the average number of calomole of ethylene oxide per glucose unit (average substitution mole, /I/a) is 2.2 to 2
．． Photographic paper with a back coat layer containing hydroxyethyl cellulose (No. 8) is not only conductive before development, but also does not lose its conductivity even when treated with chemicals such as developing solutions and bleach-fixing solutions. It is possible to prevent problems caused by static electricity during stacking and handling after processing layers.

The properties of and droxyethylcellulose change depending on the number of ethylene oxides added to one unit (glucose) of cellulose (average number of substituted moles). Usually commercially available hydroxyethyl cellulose has an average number of added moles of ethylene oxide (average number of substituted moles) per glucose unit that is less than 2.0 and is 1.6 or more. When used as an agent in the back coat layer, the conductivity of the back coat layer is lost during processing such as development and bleaching, and there is no effect in preventing the generation of static electricity.

Further, hydroxyethyl cellulose in which the average addition a of ethylene oxide (average number of moles converted to ffi) is greater than 92.8 per glucose unit is difficult to produce industrially and is therefore not suitable for practical use.

The molecular weight of the hydroxyethyl cellulose used in the present invention may be within the usual range of 30,000 to 200,000.

The content of hydroxyethylcellulose in the back coat layer of the present invention is preferably within the range of 1 to 100% by weight. That is, the back coat layer may be made of only hydroxyethyl cellulose (100% by weight), but it may also be made of 99% (by weight) of other binder resins, conductive agents, pigments, etc. in order to provide other functions. Even if the total content is as follows (weight), the effect will be exhibited. For example, natural paper (paper-like), silica, clay, calcium carbonate, amorphous silica,
Pigments such as amorphous aluminum silicate and amorphous calcium silicate may be mixed, and in order to improve the strength of the coating film, 1 synthetic rubber latex, 11!
polyvinyl acetate, acetic acid pea-acrylic copolymer, acid pea-ethylene copolymer, polyacrylate ester polyvinyl chloride,
It may be mixed with an emulsion such as a vinyl chloride-vinylidene chloride copolymer, a water-bathable polyester, a binder resin such as acrylic resin, polyvinyl alcohol, starch, casein, or gelatin. Further, in order to further improve the electrical conductivity of the photographic paper before processing such as development, the previously described inorganic salts, cationic conductive agents, and anionic conductive agents may be mixed.

The back coat layer has a dry weight of 0.01 to 5. Og/
m2, preferably 0,1 to 2,0 are formed so as to be 2. This dry N bond is 0. If it is less than OI Vm, the electrical conductivity of the puncture coat layer obtained will be insufficient for practical use, and if it is more than 5 fl/m2, the feel and appearance of the back side of the support will be different from those of plain paper, and it will be difficult to manufacture. The disadvantage is that the cost is also high.

To form the back coat layer, prepare a coating liquid with the desired composition,
This is applied to the back side of the support simultaneously with or after the formation of the polyolefin resin coating layer. There are no particular limitations on the coating method, and any of ordinary par coating, gravure coating, air knife coating, blade coating, etc. may be employed.

[Effect]

The coating layer formed on the surface of the support sheet according to the present invention imparts excellent electrical conductivity to the surface of the support sheet that will not be lost by chemical treatments such as developing, bleaching, and fixing the photographic paper. Endow.

〔Example〕

The present invention will be further explained by examples.

In each of Examples 1 to 4 and Comparative Examples 1 to 4,
Both sides of a 1759/m2 base paper were each coated with a 30 g/42 polyethylene film, and the polyethylene coating layer on the back side of the obtained support sheet was subjected to a corona discharge treatment.

Next, a coating solution having the composition shown in Table 1 is applied to the layer surface of the coated material 6 modified by this corona discharge treatment using a percoater so that the dry weight becomes the value shown in Table 1, and the drying temperature is 8.
After drying at 0°C for 60 seconds, the surface electrical resistance of the back side of the support and the surface electrical resistance of the surface after being developed with a color developer (liquid, Yoshihaku Sei N8t, etc.) in an environment of 20°C and 65 cm RH. The results are shown in Table 1.

Margin below From the results of the above Examples and Comparative Examples, it can be seen that in the Comparative Example, the surface electrical resistance before the development process is low and there is no particular problem, but the surface electrical resistance after the development process is high and the handling after the development process is difficult. Static electricity is generated and causes trouble.

In contrast, in the examples according to the present invention, the surface electrical resistance is low both before and after the development process. Therefore, the back coat layer according to the present invention is extremely effective in preventing problems caused by static electricity.

〔Effect of the invention〕

In the support for photographic paper of the present invention, the backcoat layer containing specific droxyethyl cellulose formed on the back side of the support has a great effect on preventing electrostatic charging of the photographic paper, and this effect is effective in preventing development and bleaching.

It will not be lost during chemical processing such as fixing.

Claims (1)

[Claims] 1. A base made of paper, and formed on both sides of this base,
and a support for photographic printing paper having a coating layer made of a polyolefin resin, wherein the average number of moles of ethylene oxide added per glucose unit is 2.0 to 2.0 on the surface of the coating layer on the back side of the support. The back coat layer containing hydroxyethylcellulose within the range of 0.
．． A support for photographic paper, characterized in that it is formed with a dry weight of 0.01 to 5.0 g/m^2. 2. The hydroxycellulose has a molecular weight of 30,000 to 20
Support according to claim 1, having a molecular weight of 0,000. 3. The support according to claim 1, wherein the content of hydroxyethyl cellulose in the back coat layer is within the range of 1 to 100% by weight. 4. The support according to claim 1, wherein the polyolefin resin is selected from homopolymers of ethylene and propylene, copolymers thereof, and mixtures of two or more of these polymers. 5. The support according to claim 1, wherein the back coat layer contains 99% by weight or less of an additive consisting of at least one selected from pigments and binder resins. 6. The surface of the coating layer having the back coat layer is
The support according to claim 1, which has been modified by corona discharge treatment.