JPH028275Y2 - - Google Patents

Description

[Detailed Description of the Invention] Background Technical Field of the Invention This invention relates to a post card having an image forming layer including a photosensitive silver halide emulsion layer, and more specifically, a post card with improved writing and curling properties. Regarding cards. Prior Art and its Problems In recent years, in addition to written communication, the communication of image information that directly affects the visual sense has attracted attention, and developed photographic paper is the simplest communication medium for this purpose. Attempts are being made to use them as postcards. This post card is a photographic paper that has been processed to form the image intended by the sender and is cut to postcard size, with the contents of the postal communication written on the back of the paper and sent by mail. . By the way, if you post or post photographic paper like this,
One of the technical issues required when using cards is the problem of writability. In other words, when using photographic paper as a postcard, it is desirable that it be sufficiently writable with any writing instrument, but many of the photographic papers used as postcards are not suitable for rapid processing. Due to these requirements, double-sided resin-coated paper is used, in which both sides of the paper base are coated with a hydrophobic resin such as polyethylene, and it cannot be said that this paper necessarily provides satisfactory writability. For this reason, in the past, paper was pasted on the resin-coated surface opposite to the image-forming surface to provide writing properties.
As described in Japanese Patent Application No. 52-169426, a method of imparting writability by applying a hygroscopic paint to the back side of the developed image forming surface is known. However, these methods are not always satisfactory, as the mass production of postcards and the adjustment of the paint are cumbersome, and the writing quality also suffers from bleeding. Another technical problem faced by photographic paper used as post cards is the so-called curling phenomenon in which the image forming side of the photographic paper curves inward or outward. Such curling phenomenon naturally occurs under high and low humidity conditions on paper substrates normally used as photographic paper, for example, those with a weight of 160 g/m ² to 180 g/m ² . It is necessary to suppress this as much as possible since it impedes the baking workability. For this reason, for example, in ordinary photographic paper in which both sides of the paper substrate are coated with a hydrophobic resin and a silver halide emulsion layer is coated on one of the hydrophobic resins,
The sum of the shrinkage force of the silver halide emulsion layer and the shrinkage force due to the crystallization of the hydrophobic resin (for example, polyethylene resin) is equal to the shrinkage force due to the crystallization of the hydrophobic resin on the opposite side of the silver halide emulsion layer. It is manufactured to fit perfectly, and does not cause significant curling under normal conditions. However, in the case of postcards in which the hydrophobic resin coated on the opposite side of the image forming layer is peeled off from the paper base, the bending stress of the paper base is relatively low under relatively low humidity conditions. Since it is small, it cannot withstand the sum of the shrinkage force due to dehumidification of the silver halide emulsion layer and the shrinkage force of the hydrophobic resin on the emulsion layer, causing the inconvenience of curling inward. Furthermore, even under high humidity conditions, since the bending stress of the paper base is small, it cannot resist the shrinkage force of the hydrophobic resin on the emulsion layer, resulting in curling inward. Purpose of the invention This invention was made in view of the above circumstances, and its purpose is to create an image-forming layer that can be used as a postcard and has excellent writing properties and that reduces the occurrence of curling. Our goal is to provide postcards with Specific structure of the invention A silver halide photographic material having a hydrophobic resin coating layer and a photosensitive silver halide emulsion layer on one side of a paper base, which contains a white pigment on the other side of the paper base. This is achieved by a post card having a hydrophilic colloid layer and a hydrophobic resin layer, the hydrophobic resin layer being peelable from the hydrophilic colloid layer. Hereinafter, the post card of the present invention will be explained in detail with reference to the accompanying drawings. FIG. 1 is an external view of the post card of the present invention, and FIGS. 2 and 3 are partially enlarged sectional views of the post card of the present invention. In the figure, one surface of a paper substrate 1 is coated with a hydrophobic resin coating layer 2. Further, the other surface of the paper substrate 1 is coated with a hydrophilic colloid layer 3 containing a white pigment. This hydrophilic colloid layer 3 is a layer on which predetermined information for a postcard can be printed and written on. A hydrophobic resin layer 4 is further provided on the hydrophilic colloid layer 3.
This hydrophobic resin layer 4 comprises the hydrophilic colloid layer 3
When used as a post card, the hydrophobic resin layer 4 is removed. Further, on the surface of the hydrophobic resin coating layer 2, an image forming layer 5 including at least one photosensitive silver halide emulsion layer is provided. This image forming layer 5
may be applied directly to the surface of the hydrophobic resin coating layer 2 or indirectly via an undercoat layer (not shown) or the like. The paper substrate used in the present invention is selected from materials commonly used as photographic paper. Examples of such materials include natural pulp paper, synthetic pulp paper, mixed paper of natural pulp and synthetic pulp, and various laminated papers. The outer surface of the hydrophilic colloid layer provided on the surface of the paper base of the present invention on which the photographic emulsion layer is not provided (hereinafter referred to as the back surface) is a writable surface. This hydrophilic colloid layer acts on the one hand as a writable layer and on the other hand as an anti-curl layer. That is, as shown in FIG. 2, before being used as a post card, this product is subject to the shrinkage force of both the hydrophobic resin coating layer 2 and the image forming layer 5 coated on the paper base, and the hydrophilic property. The shrinkage forces of the colloid layer 3 and the hydrophobic resin layer 4 are balanced and no curling occurs, but as shown in Figure 3, when the hydrophobic resin layer 4 on the back side is peeled off after the post card is developed. The shrinkage force of the hydrophilic colloid layer increases, and the hydrophobic resin coating layer 2 of the emulsion layer increases.
It is configured so as to balance the shrinkage forces of both the image forming layer 5 and the image forming layer 5. A specific preferred example of the hydrophilic colloid layer is a typical baryta layer used in photographic paper. This baryta layer is
For example, dissolve 8.25 g of gelatin in 200 c.c. of water, add 2.75 g of barium chloride to this, and then drop a solution of 1.35 g of ammonium sulfate dissolved in 100 c.c. of water little by little to this solution. The solution may be gelled, washed with water, added with chrome alum, and applied to a paper substrate. Colloids used in the hydrophilic colloid layer generally include gelatin, which is commonly used as a photographic emulsion, and derivative gelatin such as phthalated gelatin and malonated gelatin. ,
Agar, gum arabic, alginic acid, casein, partially hydrolyzed cellulose derivatives, partially hydrolyzed polyvinyl acetate, polyacrylamide, imidized polyacrylamide, polyvinylpyrrolidone, and copolymers of these vinyl compounds can be used. The coating amount of the hydrophilic colloid layer is 7g/m ² ~30g/
If the range is m ² , the writability and curl prevention effect can be sufficiently exhibited. In addition, when gelatin is used as the hydrophilic colloid layer, this gelatin is
It is applied in an amount of at least 5 g/m ² , preferably at least 5 g/m ² . A white inorganic pigment and/or organic pigment is added to the hydrophilic colloid layer of the present invention to provide writability. Examples of white inorganic pigments include sulfates and carbonates of alkaline earth metals such as barium sulfate and calcium carbonate, finely divided silicic acid, synthetic silicates of silica, calcium silicate, alumina, alumina hydrate, titanium oxide, and oxide. Examples include zinc, talc, clay, etc. The amount of these pigments added varies depending on the type of pigment used, the thickness of the hydrophilic colloid layer, and the purpose of the post card, but may be 10 to 80 parts by weight per 100 parts by weight of the binder. The upper surface (back side) of the hydrophilic colloid layer of the present invention and the paper substrate of the emulsion layer are coated with a hydrophobic resin layer. Such a hydrophobic resin layer serves to prevent water from being absorbed from the paper substrate during the post card development process. The resin used for this hydrophobic resin layer is
For example, polyolefins such as polyethylene, polypropylene, and polybutene; copolymers of olefins such as ethylene, propylene, and butene, and monomers such as vinyl acetate, vinylidene chloride, and maleic anhydride (e.g., ethylene-vinyl acetate copolymers, propylene- (vinylidene chloride copolymer, propylene-maleic anhydride copolymer, etc.), or polystyrene, polyvinyl chloride,
Examples include homopolymers or copolymers such as polyacrylate, saturated polyester, polycarbonate, and blends thereof. The thickness of this hydrophobic resin layer is not particularly limited, but is generally preferably about 15 to 50 microns. A conventionally known coating method is used to form a hydrophobic resin layer by coating such a hydrophobic resin on a paper substrate. A particularly common coating method includes extrusion coating. The hydrophobic resin layer coated on the image forming side of the present invention may contain a light-reflecting substance such as titanium oxide, zinc oxide, calcium carbonate, calcium sulfate, etc. to make the image clearer. These substances can be added alone or in a mixture of two or more, for example, in a range of about 5 to 25 parts by weight per 100 parts by weight of the resin. When such a hydrophobic resin layer doped with a light-reflecting substance is used, the paper substrate does not need to be coated with a baryta layer. The hydrophobic resin layer coated on the writable surface of the present invention is transparent and can be peeled off from the hydrophilic colloid layer. As a method for releasably coating the hydrophilic colloid layer with such a hydrophobic resin layer, a method of extrusion coating the resin used for the hydrophobic resin layer is usually used. In this case, the hydrophobic resin layer can be peeled off without damaging the paper base and the hydrophilic colloid layer, and no external force is applied during the manufacturing of photographic paper or during transportation during development processing. It is necessary that the adhesive adheres to the hydrophilic colloid layer to such an extent that it will not easily break or peel off even if the adhesive is used. Therefore, the peel strength between the hydrophobic resin layer and the hydrophilic colloid layer is 10~
350g weight/25mm width, preferably 50-300g weight/25mm
Width range. This peel strength is tested by pulling a 25 mm wide sample vertically at a rate of 15 cm/min. Measured using peel test method ASTM D903. Peel strength is 10
If the weight is lower than g weight, it is inconvenient that peeling may occur due to friction from rollers, etc. during the manufacturing process, processing or development of photographic paper. In addition, the peel strength
If the weight is greater than 350g, when the hydrophobic resin layer is peeled off from the hydrophilic colloid layer, the hydrophilic colloid layer may stick completely or partially to the hydrophobic resin layer, or worse, the hydrophobic resin layer may be destroyed. Therefore, the purpose of the present invention cannot be achieved. The amount of release agent per unit area required to obtain peel strength within the above range depends on the type of release agent used, the type of resin used to form the hydrophobic resin layer, and its casting conditions. Varies, but generally 0.5
It may be within the range of g/m ² to 10 g/m ² . The release agent applied to the hydrophilic colloid layer prior to coating the hydrophobic resin layer may be a polymer compound containing vinyl acetate or vinyl alcohol as a constituent, a synthetic rubber emulsion containing no carboxyl group, or acrylic acid. or polymeric compounds made of polymers of methacrylic acid or derivatives thereof, or silicone oils such as methylhydrodienepolysiloxane, hydroxyl-terminated dimethylpolysiloxane, and dimethylpolysiloxane, silicone oil emulsions, sodium methylsilicone, etc. silicone water repellents, or these silicone water repellents to which butyl titanate or organic acid salts such as aluminum, tin, lead, and zinc are added as auxiliaries, paraffin wax, wax emulsion, zirconium salts, quaternary ammonium salts such as stearoylmethylamide and methylenepyridium salts, N-methylolstearamide salts,
- Fluorocarbons such as methylol fatty acid amide, perfluoromonocarboxylic acid chlorocomplex salt and fluorinated alkyl acrylic acid ester, N,N
Amides such as -diethanololeamide, N,N-diethanolerucamide and N,N-diethanolstearylerucamide, polyvinyl carbamate, acrylic ester copolymer or polyvinyl acetate copolymer, and the like. In addition, in order to adjust the peel strength, the hydrophobic resin layer contains a peel strength reducing agent such as the following (a) to (h), and this hydrophobic resin layer is laminated on the hydrophilic colloid layer by extrusion coating method etc. A method can be used. (a) Metal soap (b) Alkyl sulfate ester salt (c) Polyoxyethylene alkyl ether sulfate ester salt (d) Polyoxyethylene alkyl ether (e) Polyoxyethylene polypyroprene glycol ether (f) Monophenolic antioxidant Agent (g) Bisphenol antioxidant (h) Polymeric phenolic antioxidant Furthermore, when extruding and coating the hydrophobic resin layer on the hydrophilic colloid layer, the casting temperature may be adjusted or the casting speed may be adjusted. The peel strength of the hydrophobic resin layer may be adjusted within a predetermined range by adjusting the balance between the thickness of the hydrophobic resin layer and the casting speed. The post card of the present invention has at least one image forming layer provided on a paper base with a hydrophobic resin coating layer interposed therebetween. This image forming layer may be any silver halide emulsion layer, and there are no particular limitations on the number and order of the silver halide emulsion layer and the non-photosensitive layer. Typical examples include color or black-and-white photographic paper, and postcards made of color photographic paper may be either monochrome or multicolor postcards. For example, post cards made of multicolor photographic paper can be constructed with silver halide emulsion layers and non-light sensitive layers arranged in various orders as known in the art. As the hydrophilic binder used in the silver halide emulsion layer and non-photosensitive layer according to the present invention, the above-mentioned colloidal substances can be used, and gelatin or gelatin derivatives are preferably used. Various coating methods such as dip coating, air doctor coating, curtain coating, and hopper coating are used to coat the silver halide emulsion layer and non-photosensitive layer used in the present invention. The silver halide used in the silver halide emulsion according to the present invention includes silver bromide, silver chloride, silver iodobromide, silver chlorobromide, silver chloroiodobromide, etc., which are commonly used in silver halide emulsions. Includes anything that In order to impart photosensitivity to these silver halides, spectral sensitization is performed using an appropriately selected spectral sensitizing dye. The silver halide emulsion layer and non-photosensitive layer constituting the image forming layer of the present invention may contain various other photographic additives. For example, antifoggants, color stain inhibitors, optical brighteners, antistatic agents, hardeners, plasticizers, wetting agents, ultraviolet absorbers, and the like can be used as appropriate. Specific Use of the Invention The post card of the present invention thus constructed can be exposed and developed using various photographic processing methods. When the postcard of the present invention is a color photographic paper, the preferred color developer used in this development process is one containing an aromatic primary amine color developing agent as a main component. A typical example of this color developing agent is p-phenylenediamine. The color developing agent may be used alone or in combination of two or more, and if necessary, in combination with a black and white developing agent such as hydroquinone. Furthermore, the color developing solution generally contains an alkaline solution such as sodium hydroxide, ammonium hydroxide, sodium carbonate, sodium sulfite, etc., and various additives such as an alkali metal halide such as potassium bromide, or a development regulator such as citrazine. It may also contain an acid or the like. The post card of the present invention may contain the above color developing agent as the color developing agent itself or as its precursor in the photographic emulsion layer constituting the image forming layer. In the thus obtained postcard, predetermined items for a postcard are printed, if necessary, on the writable surface of the hydrophilic colloid layer. When using the sender, the sender can peel off the coated hydrophobic resin layer from the hydrophilic colloid layer and clearly write the intended communication content on the hydrophilic colloid layer using an appropriate writing instrument. Specific Effects of the Present Invention In the post card of the present invention, the back side of the paper base is coated with a hydrophilic colloid layer containing a writable white pigment. Further, after the hydrophobic resin layer is peeled off, the colloid layer balances the shrinkage force of each layer on the emulsion side of the paper base, so curling is extremely rare. In addition, since the writable surface is a hydrophilic colloid layer directly coated on the paper base, it has excellent writability.
It has the following effects: it has no processing stains, provides a writing surface with an excellent texture, has a beautiful appearance, is completely free from contamination during the manufacturing process and development process of photographic paper, and is suitable for mass production. It is something to play. Specific Embodiments of the Invention The present invention will be explained in more detail by showing specific embodiments below, but the embodiments of the invention are not limited thereby. EXAMPLE The following four types of post card paper supports were prepared from paper substrates manufactured using softwood pulp bleached by the sulfate method using the alkaline method. Sample 1 Using the above pulp, thickness 153μm, weight 160
A hydrophobic resin layer was coated on one side of a paper substrate of g/m ² by extrusion coating high-density polyethylene having a density of 0.96 to a thickness of 25 μm at a casting temperature of 330°C. Next, low-density polyethylene containing 10% by weight of titanium oxide and having a density of 0.92 was applied to the other surface by extrusion to a thickness of 25 μm at a casting temperature of 330°C. Furthermore, a writability-imparting coating liquid having the following composition was applied onto the initially coated hydrophobic resin layer using a gravure coater in an amount of 2 g/m ² . Writability imparting coating liquid [Gelatin 15 parts by weight Amorphous silica (average particle size 3-5 μm) 5 parts by weight Formalin 0.03 parts by weight Isobutyl alcohol 10 parts by weight H ₂ O 70 parts by weight] Sample 2 The same pulp as Sample 1 was used. A hydrophobic resin layer was coated on one side of a paper substrate having a thickness of 153 μm and a basis weight of 160 g/m ² by extrusion coating high-density polyethylene having a density of 0.96 to a thickness of 25 μm at a casting temperature of 290°C. This hydrophobic resin layer was peelable. Next, low-density polyethylene containing 10% by weight of titanium oxide and having a density of 0.92 was extruded onto the other surface to a thickness of 25 μm at a casting temperature of 330° C. to cover the other hydrophobic resin layer. Sample 3 The post card paper support is the same as Sample 2 except that the thickness of the paper base is 184 μm and the basis weight is 200 g/ ^m2.Both sides of the paper base are coated with a hydrophobic resin layer. Manufactured in the same manner as Sample 2. Sample 4 Using the same type of pulp as that used in Sample 1, a paper base having a weight of 185 g/m ² was prepared. A hydrophilic colloid layer having the following composition was provided on one side (back side) of this paper base at a coating weight of 15 g/m ² . Gelatin...11.6g Barium sulfate...3.4g On top of this hydrophilic colloid layer, high-density polyethylene with a density of 0.96 is further applied to a thickness of 25μm and a casting temperature of 290℃.
A hydrophobic resin layer was formed by extrusion coating. This hydrophobic resin layer was made separable from the hydrophilic colloid layer. Next, low-density polyethylene with a density of 0.92 containing 10% by weight of titanium oxide was extruded and coated on the paper substrate on the emulsion side (surface) to a thickness of 25 μm at a casting temperature of 330°C to form a hydrophobic resin coating layer. . Next, for each of Samples 1, 2, 3, and 4, on the hydrophobic resin coating layer containing titanium oxide,
A blue-sensitive silver chlorobromide emulsion layer containing a yellow coupler, a first gelatin intermediate layer, a green-sensitive silver bromide emulsion layer containing a magenta coupler, a second gelatin intermediate layer, and a red-sensitive silver chlorobromide emulsion layer containing a cyan coupler. An emulsion layer and a gelatin protective layer were coated in this order to prepare a silver halide color photographic material (color photographic paper). The color photographic paper thus obtained was cut into a roll with the width of a postcard, and a portion of this paper was exposed to light through a negative film using a printer, and then subjected to a color development process to form a dye image. Sample 2 , 3 and 4, the hydrophobic resin layer on the back side was peeled off from the hydrophilic colloid layer. Samples 2 to 4 from which the hydrophobic resin layer was peeled and Sample 1 from which the hydrophobic resin layer was not peeled were cut to the size of a post card to produce individual post cards. Next, after printing predetermined items for a postcard on the back side of the postcard, a curling test was conducted to measure the occurrence and degree of curling. For curl testing at low humidity, relative humidity is 20% and temperature is 20%.
The post card size print was placed on a stand at 25°C and the degree of curl was measured after 1 hour, 3 hours and 1 day. Additionally, a high humidity curl test was performed on similar prints at a relative humidity of 80% and a temperature of 25℃.
After being left for 1 day and 4 days, the degree of curl was measured. The degree of curl here is expressed as the reciprocal of the radius of a circle corresponding to the curl (curvature) of the sample being measured, expressed in meters. Therefore, the larger the value, the greater the degree of curl. The measurement results of these curl degrees are shown in Table 1.

[Table] In Table 1, the plus (+) indicates a curl with the silver halide emulsion layer on the inside, and the minus (-) indicates the opposite. As is clear from the results in Table 1, Sample 4 of the present invention was coated with a hydrophobic resin layer on the back surface, even though the hydrophobic resin layer on the back surface was peeled off from the hydrophilic colloid layer. It can be seen that the degree of curl is smaller than that of Sample 1. On the other hand, it can be seen that in Samples 2 and 3, which are outside the scope of the present invention, the degree of curl is significantly greater than that in Sample 1 when the hydrophobic resin layer on the back side is peeled off from the paper base. Next, samples 1, 2, 3, and 4 were tested for writability as post cards. The results are shown in Table 2.

[Table] As is clear from Table 2, Sample 4, which is a postcard of the present invention, has excellent writing properties with all types of writing instruments. It also felt nice to the touch, was soft, and looked beautiful.

[Brief explanation of the drawing]

FIG. 1 is an external view of the post card of the present invention, FIG. 2 is a partially enlarged sectional view of the post card,
and FIG. 3 is a partially enlarged cross-sectional view of a part of the hydrophobic resin layer on the back side of the post card peeled off from the hydrophilic colloid layer. DESCRIPTION OF SYMBOLS 1...Paper base, 2...Hydrophobic resin coating layer, 3...
...Hydrophilic colloid layer, 4...Hydrophobic fat layer, 5...
Image forming layer.

Claims (1)

[Scope of utility model registration request] A silver halide photographic material having a hydrophobic resin coating layer and a photosensitive silver halide emulsion layer on one side of a paper substrate, a hydrophilic colloid layer containing a white pigment on the other side of the paper substrate; A post card comprising a hydrophobic resin layer, the hydrophobic resin layer being peelable from the hydrophilic colloid layer.