JPH05341439A - Substrate for photographic printing paper - Google Patents

Abstract

PURPOSE:To obtain a substrate for photographic printing paper ensuring excellent sharpness of an image, maintaining flexibility and not deteriorating the fog or sensitivity of the photographic printing paper even after storage. CONSTITUTION:A resin coating layer having a laminated structure consisting of two or more layer of cured bodies of resin compsns. each contg. an unsatd. org. compd. as an essential component is formed on the surface of a paper base. At least one of the layers contains a photo-polymn. initiator and is formed by curing by irradiation with UV. Other layer is formed by curing by irradiation with electron beams. The objective substrate for photographic printing paper is provided.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a photographic paper support. More specifically, the present invention is
A support for photographic printing paper, characterized in that the surface resin coating layer has a multilayer structure of at least two layers, and the surface resin coating layer of the multilayer structure is composed of an ultraviolet radiation cured product and an electron beam cured product. It is about the body.

[0002]

2. Description of the Related Art Conventionally, so-called baryta paper has been used as a support for photographic printing paper, which is coated with a white pigment such as barium sulfate on both sides of the paper to which strong size and strength are imparted. It is manufactured by However, in recent years, instead of this, a polyolefin-coated support produced by coating both sides of a paper base with a polyolefin resin, so-called RC paper, has been widely used. In such a support, since the polyolefin coating layer is hydrophobic, the treatment liquid hardly penetrates into the support during the developing and fixing treatment as compared with the baryta paper, and therefore the washing treatment time and the drying treatment time are longer. It has the advantage of being significantly shortened, and also has the advantage that the expansion and contraction of the support itself is suppressed and the dimensional stability is excellent because the treatment liquid does not penetrate into the paper substrate.

An inorganic white pigment such as titanium dioxide is mixed in the polyolefin resin coating layer of such a support for the purpose of improving its hiding power or resolution.
Such pigments have poor dispersibility in the resin, and have problems such as foaming in the melt extrusion step due to volatile components contained in the pigment to cause film cracking in the resin coating layer. For this reason, the pigment content in the resin coating layer cannot be increased to a level necessary for sufficiently improving the hiding power or the resolution. Generally speaking, when titanium dioxide is used, it is difficult to mix it into the resin in an amount of about 20% by weight or more. Therefore, the photographic printing paper obtained by using such a photographic printing paper support cannot be said to be sufficiently satisfactory in image sharpness.

In recent years, an electron beam curable resin coating layer obtained by applying a so-called electron beam curable resin, which is a resin composition curable by electron beam irradiation, to a support, and irradiating the substrate with the electron beam to cure the resin. A support for photographic printing paper having the following is proposed (for example, JP-B-60-17104, JP-B-60-17105, and JP-A-57-49946).
No.). According to this method, since it is not necessary to heat and melt the resin composition at a high temperature when forming the resin coating layer, the pigment content can be increased to 20 to 80% by weight. Therefore, the image sharpness of the photographic printing paper obtained by using such a support is remarkably improved as compared with the polyolefin resin-coated photographic printing paper.

However, the surface resin coating layer cured by electron beam irradiation is generally harder than the surface resin coating layer formed by melt-extruding the polyolefin resin, and thus the photographic printing paper obtained has unsatisfactory flexibility. There are many.

Further, a photographic printing paper produced by coating a photographic photosensitive layer on an electron beam curable resin coating layer is
It has been found that, if development processing is performed on this, the fog density may increase to a degree that cannot be ignored as a product or the sensitivity may change.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, has sufficient flexibility, does not cause fog on photographic printing paper even after storage for a long time, and deteriorates its sensitivity. It is an object of the present invention to provide an excellent support for photographic printing paper which does not cause the above problems.

[0008]

Means for Solving the Problems The present inventors have made a surface resin coating layer a laminated structure of two or more layers, and by constructing it with an electron beam irradiation cured body layer and an ultraviolet irradiation cured body layer, The above problems have been successfully solved, and the present invention has been completed.

That is, the photographic printing paper support of the present invention comprises:
A surface resin having a laminated structure of two or more layers formed of a paper substrate containing natural pulp as a main component and a resin composition formed on one surface of the paper substrate and containing an unsaturated organic compound as a main component. At least one layer constituting the front surface resin coating layer has a coating layer and a back surface resin coating layer which is formed on the other surface of the paper substrate and contains a film-forming synthetic resin as a main component. Formed from a cured product of a resin composition containing a polymerization initiator by ultraviolet irradiation, further the remaining layer constituting the surface resin coating layer,
It is characterized in that it is formed from a cured product of the resin composition by electron beam irradiation.

[0010]

The structure and operation of the present invention will be described below. Generally, the reason why a support for photographic printing paper having a surface resin coating layer cured by electron beam irradiation exhibits insufficient flexibility is that the resin composition having an unsaturated bond is polymerized because the electron beam has high energy. It is considered that the bond network in the resin coating layer is excessively developed due to rapid and even cross-linking.

In order to form a surface resin coating layer which secures sufficient hiding power and image resolution, a resin composition containing 20 parts by weight or more of a white pigment is added in an amount of 20 g / m ² or more (solid content). It is desired to coat the paper substrate with a coat weight. However, in this case, since it is necessary to cover the paper base material relatively thickly with the hard coating film, the flexibility of the obtained photographic paper support becomes insufficient. In addition, active radicals that are generated by electron beam irradiation and accelerate curing of the resin composition remain in the support even after curing, and this chemically reacts with the photographic light-sensitive material to cause changes in photographic sensitivity and generation of fog. It is a cause of occurrence. If only to ensure flexibility, the objective can be achieved by reducing the electron dose to be irradiated, but the surface resin coating layer produced in this way has insufficient water resistance, It cannot be used as a coating layer for photographic printing paper because it swells when it comes into contact with an alkaline solution such as a developing solution.

The present inventors have made extensive studies to solve these problems and completed the present invention. That is, a surface resin coating layer formed on one surface of a paper substrate and formed of a resin composition containing an unsaturated organic compound as a main component has a laminated structure of two or more layers, and at least
It has been found that the above problems can be solved by forming a layer by electron beam irradiation and forming another layer by irradiation of ultraviolet rays.

According to the method of the present invention, since the entire surface resin coating layer is not cured by electron beam irradiation, excessive polymerization cross-linking does not occur in the entire surface resin coating layer, and therefore flexibility is improved. Can be secured. Moreover, since the electron beam irradiation amount can be reduced, unnecessary active radicals can be suppressed from remaining, and therefore various problems such as deterioration of photographic sensitivity and occurrence of fog can be prevented.

In the present invention, the resin composition used for forming the surface resin coating layer contains an electron beam curable organic compound as a main component, and the kind of the organic compound is not particularly limited. These compounds may be monomers or oligomers and may be used alone or may be a mixture thereof.

There is no limitation on the kind of the UV-curable organic compound which is cured by UV irradiation. This ultraviolet curable resin composition is prepared by adding an appropriate amount of a photopolymerization initiator to the electron beam curable resin described above. In the present invention, the resin composition used for electron beam curing does not need a photopolymerization initiator as a matter of course, but even if it is contained, it can be used for curing by electron beam irradiation. However, a significant odor may be generated depending on the type of the photopolymerization initiator, so useless use should be avoided.

In the present invention, the unsaturated organic compound-containing resin composition used for forming the surface resin coating layer may contain a white pigment and, if necessary, other additives.

The electron beam-curable unsaturated compound used in the present invention can be selected, for example, from the following compounds. (1) Aliphatic, alicyclic and araliphatic 1 to 6 valent alcohol and polyalkylene glycol acrylate compounds (2) Aliphatic, alicyclic and araliphatic 1 to 6 valent Acrylate compounds obtained by adding alkylene oxide to alcohol (3) Polyacryloylalkyl phosphates (4) Reaction product of carboxylic acid, polyol and acrylic acid (5) Isocyanate, polyol and acrylic acid (6) Reaction product of epoxy compound and acrylic acid (7) Reaction product of epoxy compound, polyol and acrylic acid

To specifically describe these compounds,
As the electron beam curable unsaturated organic compound, polyoxyethylene epichlorohydrin-modified bisphenol A diacrylate, dicyclohexyl acrylate, epichlorohydrin-modified polyethylene glycol diacrylate,
1,6-hexanediol diacrylate, hydroxybivalic acid ester neopentyl glycol diacrylate, nonylphenoxy polyethylene glycol acrylate, ethylene oxide modified phenoxyphosphoric acid acrylate, ethylene oxide modified phthalic acid acrylate, polybutadiene acrylate, caprolactan modified tetrahydrofurfuryl Acrylate, tris (acryloxyethyl) isocyanurate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, polyethylene glycol diacrylate, 1,4-butadienediol diacrylate, neopentyl glycol Diacrylate, and Neopentyl glycol-modified trimethylol propane diacrylate and the like. In the present invention, these organic compounds may be used alone or in combination of two or more.

The photopolymerization initiator used in the present invention can be selected from generally known ones, for example, ethylanthraquinone, methylbenzoyl formate, 1-
Acetophenones such as hydroxycyclohexyl phenyl ketone, antophenone, diethoxyacetophenone, and trichloroacetophenone, o-benzoylmethyl benzoate, benzophenone, Michler's ketone, benzyl, benzoin, benzoin alkyl ether, benzyl dimethyl ketal, tetramethyl thiuram monosulfide, xanthone. , Thioxanthones, benzophenones, azo compounds and the like can be appropriately selected and used. It is also possible to use a mixture of two or more of these photopolymerization initiators.

Generally, the amount of the photopolymerization initiator added is preferably in the range of usually 0.1 to 10% by weight based on the weight of the ultraviolet curable resin. Further, it is preferable to use a known photopolymerization accelerator such as N-methyldiethanolamine or bisdiethylaminobenzophenone together with the photopolymerization initiator in order to improve the curing rate. The amount of the photopolymerization accelerator added is not particularly limited as long as the effect is exhibited, but it is generally suitable that the amount is 0.5 to 2 times the weight of the photopolymerization initiator.

The surface resin coating layer of the present invention preferably contains a white pigment for the purpose of improving the sharpness of the photographic printing paper. Titanium dioxide (anatase type and rutile type) is mainly used as the white pigment,
Besides, barium sulfate, calcium carbonate, aluminum oxide, zinc oxide, magnesium oxide and the like can all be used. The surface of the white pigment is
It may be one that has been surface-treated with a hydroxide such as aluminum or silicon.

The content of the white pigment is preferably 20 to 80% with respect to the total solid weight of the electron beam curable resin coating amount. When the content is less than 20% by weight, the sharpness of the obtained photographic image on the photographic paper may not be sufficient, and when it exceeds 80% by weight, the flexibility of the obtained resin coating layer is lowered and the film May cause cracks.

To disperse the white pigment in the electron beam-curable unsaturated organic compound as described above, a three-roll mill (three-roll mill), a two-roll mill (two-roll mill),
Cowles dissolvers, homomixers, sand grinders, paint conditioners, ultrasonic dispersers and the like can be used.

In the present invention, when the outermost layer of the surface resin coating layer is formed, the resin composition for the outermost layer is applied to the molding surface made of a metal plate or a sheet-shaped film and cured. Particularly, a metal plate having a surface plated, a metal cylindrical rotating body (drum), or a plastic sheet film can be advantageously used.

The metal cylindrical rotary body is not particularly limited in its material shape, but its surface is made of stainless steel, copper,
It is preferably covered with chrome or the like and finished into a mirror surface. Further, the sheet-shaped film is not particularly limited in its material shape, but specifically, it can be selected from plastic film, metal foil such as aluminum foil, paper, cloth, and non-woven fabric. Is preferably thin.

The resin composition may be applied to the molding surface or the paper substrate surface by, for example, bar coating, blade coating, squeeze coating, air knife coating, roll coating, gravure coating or transfer coating. Any of the above may be used. For this purpose, a fountain coater or slot die coater system can be used. Especially when the surface of a metal drum is used as the molding surface, a roll coating method using a rubber roll or an offset gravure coating method is used to prevent damage to the molding surface. Fountain coaters of the type and slot die coating methods are advantageously used.

In the present invention, the surface resin composition can be cured particularly advantageously by adopting the following method. An apparatus used in this method is shown in FIGS. 1 to 4 of the accompanying drawings. There is.

In the case of FIG. 1, the ultraviolet curable resin composition 3 for forming the outermost layer in the paint container 2 is coated with a coater 4a, 4b such as an offset gravure coater to form a metal drum 5 for forming a molding surface. To form a coating liquid layer 7a, and then the coating liquid layer 7a is cured by the ultraviolet irradiation device 6 to form a cured outermost layer 7. On the other hand, the inner coating layer forming composition 9 in the paint container 8 is coated on the paper base 11 using the coaters 10a and 10b,
The inner coating liquid layer 12 is formed, and the inner coating liquid layer 12 is formed.
Is superposed on the cured outermost layer 7 on the metal drum 5 by the guide roll 13, and the stacked layer is cured by irradiation of the electron beam irradiation device 14 to form the surface resin coating layer, and then the guide roll. At 15, the obtained paper base-surface resin coating layer laminate is peeled from the molding surface of the metal drum 5.

In the case of FIG. 2, the composition 3 for forming the outermost layer in the container 2 is coated on the surface of the metal drum 5 forming the molding surface by using coaters 4a and 4b such as an offset gravure coater. It is applied to form the coating liquid layer 7a.
On the other hand, the composition 9 for forming the inner coating layer in the container 8 is coated on the paper substrate 11 using the coaters 10a and 10b, thereby forming the inner coating liquid layer 12a, and then the coating liquid layer 12a is irradiated with ultraviolet rays. Cured using apparatus 6 to form a cured inner layer 12. The cured inner layer 12 is applied to the coating liquid layer 7a on the metal drum 5 by the guide roll 13.
The electron beam irradiation device 14
After being cured by irradiation with an electron beam from the above to form a surface resin coating layer, the obtained paper substrate-surface resin coating layer laminate 16
The guide roll 15 separates from the molding surface of the metal drum.

3 and 4 show an example in which the surface of the molding film 17 is used as a molding surface. That is, instead of the metal drum, a polymer film such as a polyester film is used for the molding surface. In these cases, the irradiation of the outermost layer-inner layer stack from the electron beam irradiation device 14 may be performed through the molding film 17 as shown in FIGS. 3 and 4, or the molding film 17 may be irradiated. Irradiation may be performed from the back surface of the paper base 11 on the opposite side. The molding film 11 can be used again after being wound up, but in that case, it may be formed into an endless belt. The molding surface film is not necessarily a polymer film, and may be a belt-shaped metal film, and the metal film may be an endless belt-shaped film.

In any case of the support for photographic printing paper of the present invention, each coating liquid layer forming the surface resin layer is cured by electron beam irradiation or ultraviolet ray irradiation, and the entire surface resin coating layer is irradiated by electron beam irradiation. Since it is not cured, it can maintain sufficient flexibility.

The total weight of the multilayer electron beam curable resin surface coating layer of the present invention is preferably ^{2 to} 60 g / m ² (solid content). The weight of the outermost resin coating layer is 0.5.
It is preferably ˜20 g / m ² (solid content).

The film-forming synthetic resin used for forming the backside resin coating layer of the present invention is a polyolefin resin used in the production of conventional photographic paper supports, or the electron beam curing resin described above. Can be used.

The polyolefin resin for forming the backside resin coating layer includes homopolymers of ethylene, α-olefins such as propylene, at least two copolymers of the above olefins, and various polymers of these. It can be selected from a mixture of at least two kinds. Particularly preferred polyolefin resins include low density polyethylene, high density polyethylene, linear low density polyethylene,
And mixtures of these. Although the molecular weight of the polyolefin resin is not particularly limited, it is usually 20,000 to 20.
Those in the range of 10,000 are used. If necessary, a small amount of an antioxidant and a lubricant may be added to the polyolefin resin. In order to form the backside resin coating layer using the polyolefin resin, usual melt extrusion coating can be used.

As the electron beam-curable unsaturated organic compound for forming the backside resin coating layer, all the compounds used for forming the above-mentioned frontside resin coating layer can be used.
Further, the method of forming the resin coating layer on the back surface may be the same as that of the above-mentioned surface resin coating layer.

The weight of the backside resin coating layer is not particularly limited, but generally it is preferably in the range of 10 to 40 g / m ² .

The electron beam accelerator used for the electron beam irradiation of the present invention is not particularly limited in its system, and for example, an electron beam irradiation device such as a van de Graaff scanning system, a double scanning system, a curtain beam system can be used. .. Among these, the curtain beam type, which is relatively inexpensive and has a large output, is effectively used. The acceleration voltage at the time of electron beam irradiation is preferably 100 to 300 kV, and the absorbed dose is preferably 0.1 to 6.0 Mrad, and particularly preferably 0.2 to 4.0 Mrad. When the absorbed dose is 0.1 Mrad or less, the curing of the resin by electron beam irradiation may be insufficient. Further, if the absorbed dose is made higher than necessary, not only is it wasteful in energy consumption, but it is also undesirable because it leads to unnecessary deterioration of the paper substrate.

The oxygen concentration in the atmosphere during electron beam irradiation is preferably 500 ppm or less. Oxygen concentration is 5
If it exceeds 00 ppm, oxygen acts as a polymerization reaction inhibitor and the curing of the resin composition may be insufficient. However, in the case of using the apparatus of the present invention, the electron beam curable resin coating liquid does not come into direct contact with air in any case, and therefore it is always necessary to particularly reduce the oxygen concentration in the atmosphere during electron beam irradiation. Absent. In addition, of course, there is no problem in flowing an inert gas such as nitrogen gas for the purpose of preventing ozone generation due to electron beam irradiation or cooling the window that generates heat when the electron beam passes through the window.

The ultraviolet irradiation device used for the ultraviolet irradiation of the present invention is not particularly limited in its system, but for example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, a metal halide lamp, etc. can be used, and these lamps are appropriately collected. In combination with a light reflector such as an optical type, a semi-condensing type, or a diffusion type, and since an ultraviolet irradiation lamp generally generates heat, it is preferable to use it by cooling with a water cooling jacket, a cold mirror, an aluminum mirror or the like. In general, in order to obtain sufficient curing, it is preferable to arrange and use a plurality of ultraviolet irradiation devices having an output of 80 w / cm or more depending on the processing speed.

After the surface resin coating layer is cured by irradiation with ultraviolet rays and electron beams, surface treatment such as corona discharge treatment is carried out for the purpose of improving adhesion with the photographic photosensitive layer,
Alternatively, an undercoat layer may be applied to the surface.

The paper base used in the present invention preferably has a weight of 50 to 300 g / m ² and has a smooth surface. Such a paper substrate can be selected from those generally used for a photographic printing paper support.

As the natural pulp forming the paper substrate, softwood pulp, hardwood pulp, hardwood mixed softwood pulp,
Etc. can be used. These natural pulps are
For example, kraft pulp, sulphite pulp, digested by a known method such as soda pulp, chlorination,
It can be selected from those bleached by a method such as alkali treatment, hypochlorite treatment, chlorine dioxide treatment, and peroxide treatment. If necessary, synthetic pulp or pulp containing synthetic fibers can also be used.

The thickness of the paper base material is preferably 50 to 300 μm, and the basis weight thereof is preferably 50 to 300 g / m ² . It is preferable that the surface of the sheet is improved by producing a sheet-shaped substrate and then compressing the sheet by applying pressure with a calendar or the like.

In the support for photographic printing paper of the present invention, a paper base material containing a magnesium compound can be advantageously used in order to suppress fog caused by electron beam irradiation. Further, the paper base material includes various usual additives such as a dry paper strengthening agent (cationized starch, cationized polyacrylamide, and anionic polyacrylamide), a sizing agent (fatty acid salt, rosin, maleated rosin, cationized size). And anionic sizing agents), fillers (such as clay, talc, kaolin, and magnesium oxide), wet strength agents (such as melamine resins and epoxidized polyamide resins), fixing agents (aluminum sulfate, and cationized starch) Etc.), a pH adjusting agent (such as caustic soda and sodium carbonate), and the like.

Further, the paper substrate includes a water-soluble polymer additive, a surface sizing agent, an inorganic electrolyte, a hygroscopic substance, a pigment, a pH adjusting agent,
It may be tab-sized or size-pressed with a treatment liquid containing one or more of a dye, an antistatic agent, polyvinyl alcohol, and carboxy-modified polyvinyl alcohol.

The coating amount of the resin coating layers on the front and back sides of the present invention is 0.5 to 50 g / m ² for each layer of the multilayer structure, and the total of the resin coating layers on the front and back sides is 10 to 100 g / m ² . Preferably. When the coating amount of each layer is less than 0.5 g / m ² , it is difficult to sufficiently exert the effects of the present invention, and coating defects such as pinholes are likely to occur in the coating process,
Further, if it exceeds 50 g / m ² and becomes a large amount, film cracking may occur in the resin coating layer or curing of the resin coating layer may become uneven. Further, if the total coating amount of the resin coating layers on both the front and back sides is less than 10 g / m ² , it becomes impossible to obtain the hiding power and resolution required for the support for photographic printing paper, and it becomes 100 g / m ² If the amount exceeds the above range, film cracking is likely to occur in the resin coating layer, and further, it is not practical in terms of manufacturing costs.

[0047]

The present invention will be described in detail with reference to the following examples, but the present invention is not limited to these embodiments.

Example 1 One surface of a paper substrate having a basis weight of 180 g / m ² was subjected to surface activation treatment by corona discharge, and then melt-extruded with a polyethylene resin to give a coating amount of 30 g / m ^2.
A backside resin coating layer of m ² was formed.

Next, a mixture having the composition shown below was mixed and dispersed by a paint conditioner for 1 hour to prepare a coating composition for forming an inner resin coating layer, and the composition was applied to the other surface of the paper substrate. A wire bar was used to apply a coating amount of 20 g / m ² after curing, and the coating layer was irradiated with ultraviolet rays from a metal halide lamp to cure the coating layer to form an inner resin coating layer. ..

The inner resin coating layer forming coating composition Ingredient Blend weight urethane acrylate oligomer 36 parts by weight (trademark: Beam Set 550B, manufactured by Arakawa Chemical Industries) bifunctional acrylate monomer 24 parts by weight (trademark: M-220, Toa Synthetic product) Titanium dioxide 40 parts by weight (Trademark: A220, Ishihara Sangyo) Photopolymerization initiator 3 parts by weight (Trademark: EDTX-S, manufactured by Nippon Kayaku) Photopolymerization accelerator 3 parts by weight (Trademark: DMBI, Japanized) Medicinal product)

Separately, a mixture having the composition shown below was mixed and dispersed by a paint conditioner for 1 hour to prepare a coating composition for forming the outermost resin coating layer, and this composition was subjected to chrome plating using a wire bar. On the surface (molding surface) of the metal plate, a coating layer is formed by coating so that the coating amount after curing is 5 g / m ² , and an inner resin coating formed on the above-mentioned paper substrate on this coating layer. The layers are superposed, and an electron beam is irradiated from the back surface of the paper substrate under the conditions of an accelerating voltage of 165 kV and an absorbed dose of 2 Mrad to cure the resin multilayer body to form a surface resin coating layer. Created.

[0052] outermost resin coating layer-forming coating composition Ingredient Blend amount pentaerythritol oligomer 80 parts by weight (trademark: Beam Set 700, Arakawa Chemical Industries, Ltd.) Titanium dioxide 20 parts by weight (trademark: A220, manufactured by Ishihara Sangyo Kaisha)

In order to evaluate the flexibility of the obtained photographic printing paper support, a sample was cut into a piece having a width of 1 cm and a length of 10 cm, the test piece was wound around a metal column having a diameter of 2 mm, and the surface resin coating layer was bent. The occurrence of cracks was visually observed and evaluated. The evaluation results were displayed in three grades, one with no cracks, Δ with slight cracks, and x with cracks.

Commercially available black-and-white photographic emulsion (trademark: Art Emulsion, manufactured by Fuji Photo Film Co., Ltd.) was coated on a support for photographic photographic paper and dried to prepare black-and-white photographic photographic paper. The properties and fog were measured to evaluate the performance of the photographic paper support.

The photographic sensitivity characteristics are as follows:
Exposure was performed using a transmission type step tablet with ΔD = 0.20, and the step tablet optical density was measured after processing with D-72 black and white developing solution and F-5 fixing solution prescribed by Eastman Kodak Company and drying. The photographic sensitivity of the photographic paper was determined by measuring and making a characteristic curve by a known method. This photographic sensitivity was expressed as a relative value with respect to 100% of the sensitivity of a photographic light-sensitive material prepared by coating a glass plate with a commercially available black and white emulsion.

As the support for photographic printing paper, it is desirable that the difference in sensitivity with respect to the emulsion layer on the glass plate is within 5%, and if it exceeds 10%, it is difficult to use it as photographic printing paper. The fog was evaluated by the black change density of the unexposed area. The photographic printing paper preferably has an optical density of less than 0.1. Table 1 shows the evaluation results of each item.

Example 2 A support for photographic printing paper was prepared and tested in the same manner as in Example 1. However, as the molding surface, a 75 μm-thick polyester film was used instead of the metal plate. The test results are shown in Table 1.

Example 3 A photographic printing paper support was prepared and tested in the same manner as in Example 1 except for the following matters. A polyethylene resin coating layer having a coating amount of 20 g / m ² was formed on one surface of a paper substrate having a basis weight of 130 g / m ² . Then, a mixture having the composition shown below is mixed and dispersed by a paint conditioner for 1 hour to prepare a coating composition for forming an inner resin coating layer.
On the other surface of the above-mentioned paper substrate, using a wire bar, the coating amount after curing is 20 g / m ² ,
An inner resin coating layer was formed.

[0059] the inner resin coating layer forming coating composition Ingredient Blend weight urethane acrylate oligomer 36 parts by weight (trademark: Beam Set 550B, manufactured by Arakawa Chemical Industries) bifunctional acrylate monomer 24 parts by weight (trademark: M-220, Toa Synthetic) Titanium dioxide 40 parts by weight (Trademark: A220, Ishihara Sangyo)

Separately, a mixture having the following composition was mixed and dispersed with a paint conditioner for 1 hour to prepare a coating composition for forming the outermost resin coating layer, and this composition was applied to the surface of a chromium-plated metal plate ( On the molding surface) using a wire bar so that the coating amount after curing becomes 5 g / m ² , and the coating layer is irradiated with ultraviolet rays by a metal halide lamp to cure the coating layer and the outermost resin. A coating layer was formed. Next, the outermost resin coating layer is overlaid with the above-mentioned inner resin coating layer formed on the paper base, and an electron beam is irradiated from the back surface of the paper base at an accelerating voltage of 165 kV and an absorbed dose of 2 Mrad. The body was cured to form a surface resin coating layer, to prepare a support for photographic printing paper. The test results are shown in Table 1.

[0061] outermost resin coating layer-forming coating composition Ingredient Blend weight urethane acrylate oligomer 65 parts by weight (trademark: New Frontier R1206, manufactured by Dai-ichi Kogyo Seiyaku) acrylate monomer 15 parts by weight (trademark: New Frontier HDDA, the Ichigo Pharmaceutical Co., Ltd.) Titanium dioxide 20 parts by weight (Trademark: A220, Ishihara Sangyo) Photopolymerization initiator 6 parts by weight (Trademark: Darocur 1173, Merck)

Comparative Example 1 A photographic printing paper support was prepared in the same manner as in Example 1. However, the coating composition was prepared by removing the photopolymerization initiator and the photopolymerization accelerator from the coating composition for forming the inner resin coating layer, and the inner coating liquid layer was cured by electron beam irradiation (accelerating voltage 165 kV, absorbed dose 2 Mrad). It was The test results are shown in Table 1.

[0063]

[Table 1]

[0064]

The photographic paper support of the present invention eliminates the general drawbacks of having an electron beam effect resin coating layer, retains flexibility, and does not deteriorate photographic sensitivity characteristics and fog. It is suitable for producing a photographic printing paper having a high content of a white pigment and excellent photographic resolution, and is extremely useful in practice.

[Brief description of drawings]

FIG. 1 is a process explanatory view showing an example of a method of forming a two-layer structure surface resin coating layer of a support for photographic printing paper of the present invention using a metal drum as a molding surface.

FIG. 2 is a process explanatory view showing another example of a method for forming a two-layer structure surface resin coating layer of the support for photographic printing paper of the present invention using a metal drum as a molding surface.

FIG. 3 is a process explanatory view showing an example of a method for forming a two-layer structured surface resin coating layer of the photographic printing paper support of the present invention by using a film material as a molding surface.

FIG. 4 is a process explanatory view showing another example of the method of forming the two-layer structure surface resin coating layer of the photographic printing paper support of the present invention by using the film-like substance as the molding surface.

[Explanation of symbols]

 1 ... Coating liquid coating and curing equipment 2, 8 ... Paint container 3 ... Outermost layer UV curable resin composition 4a, 4b, 10a, 10b ... Coater 5 ... Molding drum 6 ... UV irradiation device 7 ... Curing outermost layer 7a ... Outermost coating liquid layer 9 ... Electron beam curable resin composition for inner layer 11 ... Paper substrate 12 ... Cured inner layer 12a ... Inner coating liquid layer 13 ... Guide roll 14 ... Electron beam irradiation device 15 ... Guide roll 16 ... Paper substrate-surface resin coating layer laminate 17 ... Molding film

Claims (1)

[Claims] 1. A laminate of two or more layers formed of a paper substrate containing natural pulp as a main component, and a resin composition formed on one surface of the paper substrate and containing an unsaturated organic compound as a main component. A front surface resin coating layer having a structure, and a back surface resin coating layer formed on the other surface of the paper substrate and containing a film-forming synthetic resin as a main component,
At least one layer constituting the surface resin coating layer is formed from a cured product of the resin composition containing a photopolymerization initiator by ultraviolet irradiation, and the remaining layer constituting the surface resin coating layer is the resin. A support for photographic printing paper, which is formed from a cured product of a composition irradiated with an electron beam.