JPH02222944A - Base for photographic paper - Google Patents

Abstract

PURPOSE:To maintain specified peeling strength and to allow easy peeling of a coating layer and a joint layer by forming the joint layer consisting of a mixture composed of specific compds. between one surface of a sheet-like base body and the coating layer thereon and specifying the peeling strength between the one surface of the sheet-like base body and the coating layer. CONSTITUTION:This base includes the sheet-like base body and the coating layers which are formed on both surfaces thereof and include a polyolefin resin as an essential component. The joint layer consisting of a mixture composed of hydroxyethyl cellulose or hydroxyethyl cellulose and at least one kind of the compd. contg. a carboxyl group is formed between the one surface of the sheet-like base body and the coating layer formed thereon. The peeling strength, as specified in ASTM D 903, between the one surface of the sheet-like base body and the coating layer formed thereon is specified to 10 to 200g weight. The mixing weight ratio of the hydroxyethyl cellulose and the compds. contg. the carboxyl group of the mixture forming the joint layer is preferably 2:8 to 8:2. The sufficient joint strength is obtd. in this way and the peeling of both the layers is easily executed at need.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a support for photographic paper. More specifically, the present invention provides photographic printing paper in which the peel strength between a sheet-like substrate and a polyolefin resin coating layer formed on the surface thereof is controlled to an appropriate level that allows peeling. It is related to a support body for use.

[Conventional technology]

General photographic paper (hereinafter simply referred to as "photographic paper") is
A multilayered sheet-like substrate in which one surface of the sheet-like substrate is coated with a polyethylene resin layer containing a light-reflecting substance, a photographic emulsion layer is further coated on top of the polyethylene resin layer, and the opposite side of the sheet-like substrate is coated with a polyethylene resin layer. It has a structure. Photographic paper is also known in which an undercoat layer is provided between the polyethylene resin layer and the photographic emulsion layer in order to improve the adhesion between the two layers.

By subjecting such photographic paper to printing and development processing, a color or black and white image is formed on the photographic emulsion layer of the photographic paper. The image recorded on the photographic emulsion layer can be clearly observed due to the light reflecting substance such as titanium dioxide contained in the polyethylene resin layer and the reflection from the support.

Recently, printed and developed photographic paper is pasted on any item such as a notebook, a book, a desk, a shop window, or a postcard, like a sheet paper or a patch.
Photographic paper is desired for many purposes, such as ornamental or advertising purposes, and the emergence of photographic paper suitable for such uses has been expected.

However, the above-mentioned general photographic paper uses thick paper as a sheet-like base to prevent damage and bending, and therefore, the photographic paper that has been printed and developed can be used as it is for the Sea Nobe Patch. If pasted onto any object such as a notebook, book, desk, shop window, or postcard, the thickness of the object may become excessively large, or the sheet-like substrate may curl and adhere to the entire surface of the photographic paper. There were problems such as making it difficult to do so.

A common method to solve the above problems is to make the sheet-like substrate of the support for photographic paper thinner, but this may result in the resulting photographic paper becoming less stiff or The curl balance is disrupted, which causes new problems such as the inability to use conventional processing machines.

Furthermore, this method is extremely disadvantageous from both a practical and economic point of view, as it requires the production of a specially thin paper as a sheet-like substrate for a photographic paper support.

Conventional photographic paper supports already have a structure in which a polyolefin resin coating layer and a photographic emulsion layer are laminated on a sheet-like substrate, so utilizing this structure, A method has been proposed in which the above-mentioned problems are solved by peeling off the photographic emulsion layer together with the polyolefin resin layer from a sheet-like substrate and pasting the polyolefin resin layer and photographic emulsion layer on an arbitrary object. JP-A No. 54-92219 is directed to the manufacture of supports for photographic paper.
Then, by coating the sheet-like substrate with a polyolefin resin containing a light-reflecting substance and appropriately selecting and controlling the laminating conditions at this time, the peel strength between the sheet-like substrate and the polyolefin resin coating layer can be set to an appropriate value. The present disclosure discloses a photographic paper which can be easily peeled off from a sheet-like substrate together with a photographic emulsion layer together with a polyolefin resin coating layer.

However, in this method, the peel strength between the sheet-like substrate and the polyolefin resin coating layer varies due to slight variations in the manufacturing conditions of the photographic paper support. It has been practically difficult to obtain photographic paper from which the photographic emulsion layer can be easily peeled off together with the polyolefin resin coating layer.

[Problems to be solved by the invention] The present invention solves the above-mentioned problems of conventional photographic paper, and maintains a constant peel strength between a sheet-like substrate and a polyolefin resin coating layer. It is an object of the present invention to provide a support for photographic paper in which both layers can be easily peeled off as needed.

[Means to solve the problem]

The support for photographic paper of the present invention includes a sheet-like substrate, a coating layer formed on both surfaces thereof and containing a polyolefin resin as a main component, and one surface of the sheet-like substrate,
A bonding layer made of hydroxyethylcellulose or a mixture of hydroxyethylcellulose and at least one compound containing a carboxyl group is formed between the coating layer formed thereon, and the bonding layer is formed between one surface of the sheet-like substrate and 1. A between the coating layer formed thereon
It is characterized by a peel strength according to STM 0903 of IO to 200 g force.

Usually, photographic paper that has been printed and developed is pasted on any object such as a notebook, book, desk, shop window, or postcard, like a sea novel or patch, and used for ornamental purposes or advertising purposes. In order to
The peel strength between the sheet-like substrate and the coating layer in this photographic paper is 10 to 200 g weight, preferably 30 to 100 g weight.
If the weight is within this range, it is sufficient for practical use. When this peel strength is less than 10 g weight, delamination is likely to occur during the process of emulsion coating on the support, printing on photographic paper, development processing, etc., which is inconvenient for practical purposes. When the weight is higher than 200 g, it becomes difficult in practice to separate both layers.

The above-described predetermined peel strength of 10 to 200 g weight between the sheet-like substrate and the coating layer is obtained by adding hydroxyethylcellulose or hydroxyethylcellulose and at least one compound containing a carboxyl group between the sheet-like substrate and the coating layer. This is achieved by providing a bonding layer consisting of a mixture of. In the above mixture, the mixing weight ratio of droxyethyl cellulose and the compound containing a carboxyl group is 2:8.
The ratio is preferably 8:2 to 8:2.

Such a bonding layer is formed by peeling off the polyolefin resin coating layer from the sheet-like substrate during predetermined processes such as photographic emulsion coating and drying processes involved in photographic paper manufacturing, and printing and photographic development processing of photographic paper. The adhesive has sufficient adhesion to prevent this from occurring, and if necessary, peeling of both layers can be accomplished without difficulty.

Further, the bonding layer of the present invention does not reduce the whiteness of the support for photographic paper, and when the photographic paper is immersed in a developer and/or fixer, the cut surface of the photographic paper is Even if the sheet-like substrate comes into contact with these treatment liquids, the treatment liquid does not penetrate between the sheet-like substrate and the coating layer, so that the two do not separate. Furthermore, it does not have any harmful effect on photographic properties such as sensitivity and fog of the photographic emulsion layer.

The hydroxyethyl cellulose used in the present invention can be generally commercially available, and usually has an average degree of substitution of hydroxyl groups of 1.0 to 1.5 and an average number of substituted moles of 1.5 to 2.5. , and the molecular weight is 30.000~
- It is preferable to use one within the range of 250.000.

Furthermore, the carboxyl group-containing compound used in the present invention is
Generally commercially available products can be used, such as carboxy-modified polyvinyl alcohol, carboxy-modified styrene-butadiene copolymer, carboxy-modified acrylic acid or a polymer of its salts, or oxidized starch. However, carboxy-modified polyvinyl alcohol is particularly effective.

The carboxy-modified polyvinyl alcohol has a carboxyl group content of 1 to 20 mol% and a molecular weight of 4.
Those within the range of 0.000 to 130.000 can be preferably used.

The bonding layer of the present invention includes hydroxyethyl cellulose and
The main component is a mixture of hydroxyethyl cellulose and at least one compound containing a carboxyl group, but up to 5% by weight of additives, such as a spreadability improver, an antifoaming agent, etc., can also be added thereto. .

The coating amount of the bonding layer of the present invention is not particularly limited as long as the above peel strength is achieved, but it is generally 0.05 to 5 g.
/m' is preferable.

When the coating amount of the bonding layer is less than 0.05 g/m', the peel strength between the sheet-like substrate and the coating layer may be insufficient. Moreover, if it exceeds 5 g/m', the peel strength may become too low, and the cost increases excessively, making it impractical.

The bonding layer of the present invention can be formed by conventional coating methods such as air knife coating, blade coating, bar code coating, gravure coating, and die coating. or,
The sheet-like substrate is immersed in a solution in which the compound constituting the bonding layer of the present invention is dissolved and dispersed, and then the excess compound solution and dispersion is removed using a pair of rolls, which is the so-called size press method. It is also possible to form a bonding layer.

As the sheet-like substrate used in the present invention, base paper made of wood pulp such as hardwood pulp, softwood pulp, hardwood mixed pulp, etc. is advantageously used. Alternatively, base paper made of commonly used bleached pulp such as kraft pulp, sulfide pulp, and soda pulp may be used.

Furthermore, base paper manufactured from synthetic pulp or pulp containing synthetic fibers can also be used, if necessary.

There are no particular restrictions on the type and thickness of the sheet-like substrate, but it is preferable that the sheet-like substrate is produced and then compressed by applying pressure using a calendar or the like to improve its surface smoothness. Basis weight is 50-250 g/m
'', and its thickness is preferably 50 to 250 ρ.

In the support of the present invention, the base paper used as the sheet-like substrate may contain various conventional additives, such as dry paper strength enhancers (
cationic starch, cationic polyacrylamide, and anionic polyacrylamide), sizing agents (fatty acid salts, rosin, maleated rosin, cationic sizing agents, and reactive sizing agents, etc.), additives (clay, talc, and kaolin, etc.), wet paper strength agents (melamine resins, epoxidized polyamide resins, etc.), fixing agents (aluminum sulfate, cationized starch, etc.), pH adjusters (caustic soda, soda carbonate, etc.), etc. May contain.

In addition, the base paper is treated with a treatment liquid containing one or more of water-soluble polymer additives, sizing agents, inorganic electrolytes, hygroscopic substances, pigments, pH regulators, polyvinyl alcohol, and carboxy-modified polyvinyl alcohol base paper to improve tab size or size. It may be pressed.

In the support of the present invention, the polyolefin resin used to coat both sides of the sheet-like substrate is ethylene,
homopolymers of α-olefins, such as propylene, or copolymers of at least two of the above-mentioned olefins;
It can also be selected from mixtures of at least two of these various 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 polyolefin resin, but it is usually between 20.0.00 and 2.0.
A value in the range 00,000 is used. Each coating layer is
Generally 10-50 g/m', preferably 20-40 g
/m'' coating amount on a sheet-like substrate.

A white pigment such as titanium dioxide is dispersed and mixed in the polyolefin resin used for the coating layer on the surface of the support (layer where the photographic emulsion layer is provided), but in addition, colored pigments, optical brighteners, and antioxidants are mixed. , and various additives such as a dispersant may be added.

The back side of the support (the side opposite to the side on which the photographic emulsion layer is provided)
The polyolefin used for coating is generally low-density polyethylene, high-density polyethylene, or a mixture of low-density polyethylene and high-density polyethylene, which is applied by melt extrusion. This layer is generally often matted.

When forming the coating layers on the front and back sides of the support, in order to improve the flatness of the developed photographic paper in the normal use environment, the density of the resin layer on the front side is made slightly smaller than that on the back side, or the density of the resin layer on the back side is made smaller than that on the back side. Measures such as increasing the weight of the resin coating layer are used.

Generally, the coating layers on both the front and back surfaces are formed on a sheet-like substrate by a melt extrusion coating method from a polyolefin resin composition. To carry out this melt extrusion coating, typically
A polyolefin resin composition is melt-extruded and coated onto a traveling sheet-like substrate from a T-guidance of an extruder in the form of a single layer or multiple layers of film. Usually, the melt extrusion temperature is preferably 250°C to 350°C.

The bonding layer of the present invention does not undergo surface activation treatment of the sheet-like substrate by corona discharge treatment or flame treatment, etc.
It is preferable to apply the front side resin coating layer by melt extrusion.

However, in order to improve the adhesion to the polyolefin resin coating layer on the back side of the sheet-like substrate, which does not require peeling, the polyolefin resin composition is coated on the back side of the sheet-like substrate by melt extrusion. It is preferable to subject the back surface to activation treatment such as corona discharge treatment or flame treatment.

In addition, if necessary, an undercoat layer may be provided on the front resin coating layer to improve adhesion with the photographic emulsion layer.
Alternatively, a back coat layer may be provided on the back resin coating layer to improve printing and writing properties and antistatic properties.

〔Example〕

The present invention will be explained below with reference to Examples, but the scope of the present invention is not limited by these Examples.

Examples 1 to 9 right and Comparative Examples 1 to 6 In each of Examples 1 to 9 and Comparative Examples 1 to 6, high-quality paper with a basis weight of 170 g/m' was used as a sheet-like substrate, and one surface of the paper was subjected to corona discharge. After the treatment, a coating layer having a thickness of 27 mm was formed using a polyethylene resin having a density of 0.942 and an MI of 8 by an extrusion coating method. In addition, on the opposite side of the high-quality paper, a bonding layer having the composition and coating amount shown in Table 1 is provided, and a bonding layer containing 10% by weight of titanium dioxide is coated on the bonding layer using a melt extrusion coating method at a resin temperature of 330°C. .936, MI: Made of a polyethylene resin composition of 7, thickness 27I! A coating layer of m was formed.

The peel strength between the high-quality paper on the surface side of the photographic paper support prepared by the above method and the resin composition was determined according to ASTM D.
903 test method. The results are shown in Table 1.

In Table 1, in Examples 1 to 3, the bonding layer is composed only of hydroxyethylcellulose, and in Examples 4 to
The bonding layer No. 8 was composed of a mixture of hydroxyethyl cellulose and carboxy-modified polyvinyl alcohol.

In the photographic paper supports of Examples 1 to 3 and Examples 4 to 9 according to the present invention, the peel strength between the sheet-like substrate and the coating layer was within a practical range.

However, those with no bonding layer applied (Comparative Example 1) and those with too little bonding layer applied (Comparative Examples 2 and 4)
In the case where a material different from that in this patent was applied (Comparative Example 6), the peel strength between the sheet-like substrate and the resin coating layer was excessive, and it was unsuitable for applications requiring peeling.

Furthermore, in cases where the bonding layer was applied in an excessive amount (Comparative Examples 3 and 5), the peel strength between the sheet-like substrate and the resin coating layer was too low, and this was not suitable for the intended use of the present invention. It is appropriate.

The following margins [Effects of the present invention] According to the present invention, the peel strength between the polyolefin resin coating layer and the sheet-like substrate can be controlled to an appropriate level that allows peeling, thereby enabling various applications that require peeling. It is possible to provide a support for photographic paper that can be used for.

Claims (1)

[Claims] 1. A sheet-like substrate and a coating layer formed on both surfaces thereof and containing a polyolefin resin as a main component, between one surface of the sheet-like substrate and the coating layer formed thereon, A bonding layer made of hydroxyethylcellulose or a mixture of hydroxyethylcellulose and at least one compound containing a carboxyl group is formed between one surface of the sheet-like substrate and the coating layer formed thereon. A support for photographic paper having a peel strength of 10 to 200 g weight according to ASTM D903.