JP3235474B2 - Photographic paper support - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photographic printing paper support. More specifically, the present invention relates to a photographic printing paper support which suppresses curling curl generated during storage and curling of photographic printing paper generated after development processing, and maintains sufficient flexibility.

[0002]

2. Description of the Related Art Conventionally, as a support for photographic printing paper,
A polyolefin resin-coated support produced by coating a polyolefin resin on both sides of a paper substrate has been widely used, but the photographic printing paper obtained using such a photographic printing paper support has high image sharpness. Was not satisfactory.

In recent years, Japanese Patent Publication No. Sho 60-17104, Japanese Patent Publication No. Sho 60-17105, and Japanese Patent Application Laid-Open No. Sho 57-49946.
Japanese Patent Application Laid-Open Publication No. H11-163,086 discloses a photographic printing paper support in which a coating composition containing an electron beam-curable unsaturated organic compound as a main component (hereinafter, referred to as an electron beam-curable resin composition) is applied to the support. I have.

[0004] The image sharpness and smoothness of a photographic printing paper obtained using such a photographic printing paper support are remarkably improved as compared with the photographic printing paper obtained using a polyolefin resin-coated support. .

[0005] The packaging and preservation of photographic printing paper can be roughly classified into two types: sheet-like material and roll-like material. However, in recent years, exposure and development processing of photographic printing paper have been automated and speeded up.
The proportion occupied by the rolls is increasing. A major problem with rolls is curl that occurs during storage. In practice, the curl curl causes a problem such as a paper jam in a transport unit of an exposure device or an automatic developing device, or a jumping-up at the time of sticking to a mount. The degree of curl curl depends on the size of the winding diameter, environmental factors such as aging in the wound state, temperature, humidity, etc., as well as the thickness and rigidity of the photographic paper support, the electron beam curable resin coating layer, and the undercoat. The properties of the photographic printing paper support itself, such as the viscoelasticity of the resin coating layer and the backside resin coating layer, have a significant effect.

Further, photographic printing paper coated with a photographic emulsion has a problem that curling in which the emulsion layer side is inside due to drying of the emulsion after development processing (hereinafter referred to as photographic printing paper curl) has been known. Curling has been performed in advance on the back side of the support.

Further, at the time of processing a surface resin coating layer of a conventional photographic printing paper support coated with a polyolefin resin, the temperature is 200 ° C.
Since the polyolefin resin is melt-extruded and coated with the heat-melted polyolefin resin as described above, the curling of the surface resin coating layer inside due to the cooling shrinkage of the polyolefin resin occurs.

As a countermeasure against such curling of the photographic paper support and curling of the photographic paper, a curl is previously formed on the back side, and the resin density of the polyolefin resin used for the backside resin coating layer is increased. Japanese Patent Publication No. 48-9963 discloses that the density is higher than the resin density of the polyolefin resin used for the surface resin coating layer. For this reason, a mixture of high-density polyethylene (hereinafter, referred to as HDPE) and low-density polyethylene (hereinafter, referred to as LDPE) is generally used for forming the backside resin coating layer.
It is known that a large amount of HDPE is blended to increase the apparent resin density and improve the curl property.

However, in a photographic printing paper support coated with an electron beam-curable resin composition, no heat other than reaction heat generated by a curing reaction caused by electron beam irradiation is performed when forming a surface resin cured layer. Therefore, immediately after processing due to cooling shrinkage, curl with the surface resin cured layer inside does not occur, and after storage in the wound state with the surface resin cured layer outside, the surface resin cured layer is outside. The problem that the curling curl becomes large remains.

For a photographic printing paper support having a surface resin cured layer formed from such an electron beam-curable resin composition, to improve curl curl, the appearance of a polyolefin resin used for the back resin coating layer can be improved. It is known that the smaller the resin density, the smaller the curl in curl. However, in order to improve the water vapor barrier property of the surface resin cured layer and the stability of the surface gloss, when the undercoat resin coating layer is formed,
The photographic paper curl increases. As the photographic paper curl, it is advantageous that the apparent resin density of the polyolefin resin used for the undercoat resin coating layer is small, but in this case, the apparent resin density and the coating amount of the polyolefin resin used for the backside resin coating layer are changed. Just by itself, it is not possible to obtain a sufficient effect for improving the curl curl.

As described above, in a photographic printing paper support having a front surface resin coating layer formed from an electron beam curable resin composition on an undercoat resin coating layer having a small apparent resin density and having a back surface resin coating layer, Curl curl and photographic paper curl occurred, and it was not possible to suppress the occurrence of curl when used as photographic paper.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, suppress curl curl and photographic paper curl during storage, and provide a flexible, smooth surface and image sharpness. An object of the present invention is to provide a photographic printing paper support suitable for producing a photographic printing paper excellent in the above.

[0013]

Means for Solving the Problems The present inventors have made various studies to improve the curl curl and photographic paper curl, which are the problems described above, and as a result, the undercoat resin coating layer contains polyethylene as a main component. Due to the apparent resin density of the polyethylene resin composition, when the photographic printing paper support is wound into a roll, the undercoating resin coating layer is hardly deformed, thereby suppressing the occurrence of curl and photographic paper curling. Thus, the present invention has been completed.

The photographic printing paper support according to the present invention mainly comprises a paper base containing natural pulp as a main component and a film-forming synthetic resin formed on one surface of the paper base on which a photographic emulsion layer is formed. An undercoat resin coating layer containing as an ingredient, an electron beam cured product of a coating composition formed on the undercoat resin coating layer and containing an electron beam-curable unsaturated organic compound as a main component, and containing titanium dioxide. At least one surface resin cured layer, formed on the other surface of the paper substrate,
And a photographic printing paper support comprising a back surface resin coating layer containing a film-forming synthetic resin as a main component, wherein the film-forming synthetic resin used for the undercoating resin coating layer is a polyethylene resin composition containing polyethylene as a main component. Consisting of an apparent resin density of 0.935 to 0.960 g
/ Cc.

[0015]

The curl of curling and the curling of photographic paper according to the present invention are not controlled by a manufacturing method such as a coating method when the surface resin cured layer has a multilayer structure. Improves flexibility and flexibility by using an electron beam curable resin composition that shares functions such as liquid permeation prevention and interference fringe prevention and has a layer structure of two or more cured surface resin layers. It is also possible.

An inorganic white pigment such as titanium dioxide is mixed in the surface resin cured layer of the photographic printing paper support of the present invention for the purpose of improving concealing properties and image sharpness. The polyolefin resin conventionally used is inferior in dispersibility and the volatile components contained in the pigment generate bubbles in the melt-extrusion coating process. Have difficulty. However, by using an electron beam-cured material for the cured surface resin layer, it is not necessary to heat and fuse the cured surface resin layer, and up to 80% by weight of the pigment can be blended. Significantly improved. Furthermore, since there is no expansion due to heating and no shrinkage due to cooling, the surface of the surface resin cured layer formed by casting, which is pressed against a highly smooth surface such as a metal drum or polyester film and cured and transferred, is melt-extruded and coated with a polyolefin resin. The smoothness is significantly higher than the surface of the surface resin coating layer.

In the photographic printing paper support of the present invention, the polyethylene for forming the undercoating resin coating layer may be LDPE having a resin density of 0.905 to 0.925 g / cc or resin density of 0.941 to 0.965 g. / Cc HDPE,
Linear low-density polyethylene (hereinafter referred to as L-LDPE) having a resin density of 0.926 to 0.940 g / cc can be used, and these are used alone or as a polyethylene resin composition in which these are mixed. In order to exert the function of the undercoat resin coating layer and suppress curl curl and photographic paper curl, the apparent resin density of the synthetic resin of the polyethylene resin composition is preferably 0.935 to 0.965 g.
/ Cc, more preferably 0.940 to 0.960 g / c
c. When the apparent resin density of the synthetic resin of the undercoating resin coating layer is less than 0.935 g / cc, curl of curling becomes large. The resin density of commonly available polyethylene is
Those having a resin density of 0.965 g / cc are the largest, and those having a resin density higher than 0.965 g / cc are difficult to obtain.

In the photographic paper support of the present invention, in order to exhibit the function of the undercoating resin coating layer and to suppress curl curl and photographic paper curl, the coating amount of the polyethylene resin composition is 10 to 10. is preferably 35 g / m ^2, more preferably from 13~30g / m ^2. When the coating amount of the undercoat resin coating layer is less than 10 g / m ² , the smoothness of the undercoat layer is deteriorated, and when the paper is used as a photographic paper, the emulsion layer shrinks due to a change in environmental humidity. The resulting surface instability is increased. 3
If it exceeds 5 g / m ² , the balance with the backside resin coating layer will be lost, and the photographic paper curl of the support will increase. Further, in order to maintain the curl balance, it is necessary to increase the thickness of the backside resin coating layer, which is also costly.

The molecular weight of the polyethylene used in the polyethylene resin composition used in the undercoat resin coating layer of the present invention is not particularly limited, but is usually from 20,000 to 200,000.
A range of 0 is used. If necessary, additives such as a white pigment, an antioxidant, and a lubricant may be added to the polyethylene resin composition. In order to form the undercoat resin coating layer using the polyethylene resin composition, a usual melt extrusion coating method can be used.

Particularly preferred polyethylene resins for forming the backside resin coating layer of the present invention are the aforementioned LDPE and HDP.
E, L·LDPE can be used, and these are used alone or as a polyethylene resin composition in which these are mixed, and it is advantageous that the apparent resin density is higher in terms of balance and cost of photographic paper curl.

In the photographic printing paper support of the present invention, in order to suppress photographic printing paper curl, the coating amount of the backside resin coating layer is preferably 10 to 60 g / m ² , more preferably 13 to 60 g / m ^2. it is desirable to take a curl balance in the range of ~55g / m ^2.

The molecular weight of the polyethylene used in the polyethylene resin composition used for the backside resin coating layer of the present invention is not particularly limited, but is usually 20,000 to 200, 200, similar to the polyethylene used for the undercoating resin coating layer. 000 range is used. If necessary, additives such as a white pigment, an antioxidant, and a lubricant may be added to the polyethylene resin composition. In order to form the undercoat resin coating layer using the polyethylene resin composition, ordinary melt extrusion coating can be used.

The unsaturated organic compound in the electron beam-curable resin composition used for forming the cured surface resin layer of the present invention may be a monomer alone, an oligomer alone, or a mixture thereof. The type of the compound is not particularly limited. The unsaturated organic compound can be selected from, for example, the following compounds. (1) Acrylic, alicyclic, and aromatic alcohol and polyalkylene glycol acrylate compounds. (2) Acrylate compounds obtained by adding alkylene oxide to aliphatic, alicyclic, and aromatic alcohols. (3) Polyacryloyl alkyl phosphates. (4) A reaction product of a polybasic acid, a polyol, and acrylic acid. (5) A reaction product of an isocyanate, a polyol, and acrylic acid. (6) A reaction product of an epoxy compound and acrylic acid. (7) A reaction product of an epoxy compound, a polyol, and acrylic acid.

More specifically, as the electron beam-curable unsaturated organic compound, methyl acrylate, ethyl acrylate, butyl acrylate, lauryl acrylate, stearyl acrylate, N-vinylpyrrolidone,
Acryloyl morpholine, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate,
2-hydroxybutyl acrylate, 2-hydroxybutyl methacrylate, tetrahydrofurfuryl acrylate, tetrahydrofurfuryl methacrylate, caprolactone-modified tetrahydrofurfuryl acrylate, cyclohexyl acrylate, cyclohexyl methacrylate, dicyclohexyl acrylate, isobornyl acrylate, isobornyl methacrylate, benzyl acrylate Benzyl methacrylate, ethoxydiethylene glycol acrylate, methoxytriethylene glycol acrylate, methoxypropylene glycol acrylate, polyethylene glycol diacrylate, epichlorohydrin-modified polyethylene glycol diacrylate, nonylphenoxy polyethylene glycol acrylate, Alkylene oxide-modified phenoxy acrylate, N, N-dimethylaminoethyl acrylate, N, N-dimethylaminoethyl methacrylate,
1,4-butanediol diacrylate-1,4-butanediol dimethacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, diethylene glycol diacrylate, tripropylene glycol diacrylate, trimethylolpropane tri Acrylate, ethylene oxide-modified trimethylolpropane triacrylate, propylene oxide-modified trimethylolpropane triacrylate, neopentyl glycol-modified trimethylolpropane diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol tetraacrylate, dipenta Erythritol pentaacrylate, dipentaerythritol hexaacrylate , Caprolactone-modified dipentaerythritol hexaacrylate, polyoxyethylene epichlorohydrin-modified bisphenol A diacrylate, ethylene oxide-modified bisphenol A diacrylate, propylene oxide-modified bisphenol A diacrylate, neopentyl glycol diacrylate, hydroxybivalate neopentyl glycol diacrylate It is preferably selected from acrylates, ethylene oxide-modified phenoxylated phosphoric acid acrylate, ethylene oxide-modified phthalic acid acrylate, polybutadiene acrylate, tris (acryloxyethyl) isocyanurate, and the like. These compounds can be used alone or in combination of two or more.

In the present invention, the cured surface resin layer is mainly composed of an electron beam-curable resin composition which is a mixture of an electron beam-curable unsaturated organic compound and a white pigment, and optionally contains other additives. Can be included. As the white pigment, anatase-type and rutile-type titanium dioxide are mainly used.In addition, any of barium sulfate, calcium carbonate, aluminum oxide, zinc oxide, magnesium oxide and magnesium hydroxide can be used. . The content of the white pigment is 20 to 80% by weight, preferably 30 to 60% by weight, based on the total solid weight of the cured surface resin layer. When the content is less than 20% by weight, the image sharpness of the photographic image obtained on the photographic printing paper is insufficient, and when the content is more than 80% by weight, the flexibility of the obtained surface resin cured layer decreases, The film cracks.

In the present invention, the coating amount of the surface resin cured layer is 10 to 50 g / cured after the curing of the electron beam curable resin composition.
m ² , preferably 15 to 30 g / m ² . 10g / m
^When the coating amount is less than ² , the surface smoothness of the photographic paper support,
When the whiteness and the image clarity are inferior and exceed 50 g / m ² ,
Increases cost.

The paper substrate used in the present invention generally has a basis weight of 50 to 300 g / m ² and has a smooth surface. The paper substrate can be selected from all of those used for general photographic printing paper supports. Examples of usable natural pulp include coniferous pulp, maple, and beech produced from fir and toga. , Hardwood pulp manufactured from poplar, etc., those mainly containing natural pulp such as softwood mixed pulp are widely used, kraft pulp,
Bleached chemical pulp such as sulfite pulp and soda pulp can be used.

In order to prevent fogging of the photographic printing paper produced from the paper substrate of the present invention during long-term storage, the paper substrate contains a magnesium compound such as magnesium hydroxide, magnesium oxide or magnesium salt. Is valid. Further, the paper substrate may contain additives generally used for papermaking, such as a sizing agent, a fixing agent, a paper strength enhancer, a filler, an antistatic agent, a pH adjuster, a pigment, and a dye. Further, a surface sizing agent, a surface paper strength agent, a pigment, a dye, an antistatic agent and the like may be appropriately applied to the surface.

In the present invention, as the electron beam accelerator used for electron beam irradiation, any of a Van de Graff type scanning system, a double scanning system, and a curtain beam system can be used. The system of the type is advantageously 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 Mrad, particularly preferably 0.2 to 4.0 Mrad.

The oxygen concentration in the atmosphere during electron beam irradiation is 1000 ppm or less, preferably 500 ppm or less. When the oxygen concentration is higher than 1000 ppm, the polymerization reaction of the electron beam-curable resin composition is inhibited by the presence of oxygen, and the curing may be insufficient. However, there is of course no problem in using an inert gas to lower the oxygen concentration for the purpose of suppressing ozone generation due to electron beam irradiation or for cooling a window that generates heat when the electron beam passes. In addition, the type of coexisting gas and its concentration,
The temperature and humidity of the atmosphere are not particularly limited, and coexistence with an inert gas such as a nitrogen gas or an argon gas is also acceptable.

[0031]

EXAMPLES The structure and effects of the present invention will be further described with reference to the following examples, but the present invention is not limited to these embodiments.

Example 1 A back surface of a paper substrate having a basis weight of 180 g / m ² was subjected to a surface activation treatment by corona discharge, and a polyethylene resin (composition 1) having the following composition was melt-extruded and coated thereon. And a back surface resin coating layer having a coating amount of 27 g / m ² . Composition 1 Ingredient weight polyethylene resin 100 parts by weight (trademark: HY430, manufactured by Mitsubishi Chemical Corporation resin density 0.953 g / cc)

Further, the surface of the paper substrate was subjected to a surface activation treatment by corona discharge, and a polyethylene resin (composition 2) having the following composition was melt-extruded and coated thereon, and the coating amount was 10 g / m ^2. Was formed. Composition 2 Ingredient weight polyethylene resin 100 parts by weight (trademark: HY331, manufactured by Mitsubishi Chemical Corporation resin density 0.951 g / cc)

Separately, as an electron beam-curable resin composition, an electron beam-curable organic compound having the following composition (composition 3):
The white pigment mixture composition was mixed and dispersed with a paint conditioner for 1 hour to prepare an electron beam-curable resin composition. Composition 3 Ingredient weight polyester acrylate 30 parts by weight (trademark: Aronix M7100, manufactured by Toagosei Co., Ltd.) 1,6-hexanediol diacrylate 20 parts by weight (trademark: HDDA, manufactured by Nippon Kayaku Co., Ltd.) Titanium dioxide (trademark: Taipaque A-220, manufactured by Ishihara Sangyo Co., Ltd.) 50 parts by weight

The above-mentioned electron beam-curable resin composition (composition 3)
On the surface of the sheet-like substrate, using a wire bar,
The coating liquid was applied so that the coating amount after curing became 25 g / m ² , and this coating liquid layer was superimposed on the polyester film molding surface, and an electron beam was applied from the surface side of the paper substrate under the conditions of an acceleration voltage of 175 kV and an absorbed dose of 2 Mrad. And cured, and then the polyester film was peeled off to obtain a photographic printing paper support.

The curl of curl and the curl of the photographic paper during storage of the obtained photographic printing paper support were evaluated by the following methods. The evaluation results are shown in the table. 1. Curl curl (Adjustment of sample) A sample of the photographic printing paper support having a size of 89 mm in the width direction and 140 mm in the flow direction is placed flat at 20 ° C. and 65%
Leave in the RH atmosphere for one week. A photographic printing paper support having a size of 89 mm in the width direction and 300 mm in the flow direction is allowed to stand in an atmosphere of 20 ° C. and 65% RH for one week, and used as a patch for measurement.

(Treatment) A curl measurement sample is prepared by wrapping a cured resin layer on the surface of a sample around a paper tube having an outer diameter of 88 mm with the surface resin cured layer facing outside, and wrapping a wrapping paper thereon and fixing it with an adhesive tape. Under an atmosphere of 20 ° C. and 65% RH, the sample was placed in a bag of a polyester film having a barrier property in an amount of 1 to 2 per bag.
Individually, sealed, and left in a thermostat at 40 ° C. for 5 hours. Then, it is taken out from the thermostat layer and left for 30 minutes in an atmosphere of 20 ° C. and 65% RH.

(Measurement) After opening the bag having barrier properties, the backing paper is removed and a sample is taken out. The curl degree of the sample was measured by the following formula based on JAPAN TAPPI paper pulp test method No. 16-77 “paper curl test method II”. +: Shows curl with the backside resin coating layer on the outside. -: Curling with the back resin coating layer inside. Curl degree = 100 / curl radius (cm) (Evaluation criteria of curl degree) -17 or more: practical (absolute value of numerical value is small) Less than -17: impractical (absolute value of numerical value is large)

2. Curl of photographic paper (pretreatment) The surface of the cured resin layer of the support for the test photo photographic paper is subjected to a corona discharge treatment, and a photographic emulsion for black-and-white photography (Rockland Colloid Co., Ltd., trademark: Likit) Light) is applied to a thickness of 15 μm after drying to prepare a photographic printing paper.

(Treatment and Measurement) A test photographic paper having a size of 10 cm × 10 cm was left in an atmosphere of 20 ° C. and 65% RH for 16 hours, and then placed on a horizontal surface with the surface resin cured layer facing upward. The distance between the four corners and the plane was measured, the average value was calculated, and the result was evaluated in the following four steps. (According to the study of the present inventors, the evaluation method of the photographic paper curl has the same tendency as the curl after the development processing.) A: The average distance from the flat surface of the four corners of the photographic paper is less than 1 mm. B: The average distance from the plane at the four corners of the photographic paper is 1 mm or more and less than 2 mm. C: The average distance from the plane at the four corners of the photographic paper is 2 mm or more and less than 4 mm. D: The average distance from the plane at the four corners of the photographic paper is 4 mm or more. (Evaluation criteria) A and B: No problem in practical use C and D: Unavailable

Example 2 The same operation as in Example 1 was performed. However, an undercoating resin coating layer was formed at a coating amount of the composition 2 of 15 g / m ² . The results of evaluation performed in the same manner as in Example 1 are shown in the table.

Example 3 The same operation as in Example 1 was performed. However, an undercoating resin coating layer was formed at a coating amount of the composition 1 of 25 g / m ² . The results of evaluation performed in the same manner as in Example 1 are shown in the table.

Example 4 The same operation as in Example 1 was performed. However, an undercoating resin coating layer was formed at a coating amount of the composition 1 of 35 g / m ² . The results of evaluation performed in the same manner as in Example 1 are shown in the table.

Example 5 The same operation as in Example 1 was performed. However, Composition 4 was prepared and used in place of Composition 2, and the coating amount of Composition 4 was 20 g / m ² to form an undercoat resin coating layer. The results of evaluation performed in the same manner as in Example 1 are shown in the table. Composition 4 Ingredient weight polyethylene resin 65 parts by weight (trademark: LC-522, manufactured by Mitsubishi Chemical Corporation, resin density 0.923 g / cc) 35 parts by weight of polyethylene resin (trademark: EX10S, manufactured by Mitsubishi Chemical Corporation, resin density 0 (Note) The resin density after compounding is 0.937 g / cc.

Example 6 The same operation as in Example 1 was performed. However, composition 5 was prepared and used in place of composition 2, and the coating amount of composition 5 was 15 g / m ² to form an undercoat resin coating layer. The results of evaluation performed in the same manner as in Example 1 are shown in the table. Composition 5 Ingredient weight polyethylene resin 35 parts by weight (trademark: LC-522, manufactured by Mitsubishi Chemical Corporation, resin density 0.923 g / cc) polyethylene resin 65 parts by weight (trademark: EX10S, manufactured by Mitsubishi Chemical Corporation, resin density 0 (Note) The resin density after compounding is 0.949 g / cc.

Example 7 The same operation as in Example 1 was performed. However, composition 6 was prepared and used in place of composition 2, and the coating amount of composition 6 was 15 g / m ² to form an undercoat resin coating layer. The results of evaluation performed in the same manner as in Example 1 are shown in the table. Composition 6 Ingredient weight polyethylene resin 30 parts by weight (trademark: LC-522, manufactured by Mitsubishi Chemical Corporation, resin density 0.923 g / cc) polyethylene resin 57 parts by weight (trademark: EX10S, manufactured by Mitsubishi Chemical Corporation, resin density 0 .964 g / cc) Titanium dioxide (trade name: Taipaque A-220 manufactured by Ishihara Sangyo) 13 parts by weight (Note) The resin density after compounding is 0.950 g / cc.

Example 8 The same operation as in Example 7 was performed. However, the composition 7 was prepared and used in place of the composition 1, and the coating amount of the composition 7 was set to 25 g / m ² to form a back resin coating layer. The results of evaluation performed in the same manner as in Example 1 are shown in the table. Composition 7 Ingredient weight polyethylene resin 35 parts by weight (trademark: LC-522, manufactured by Mitsubishi Chemical Corporation, resin density 0.923 g / cc) polyethylene resin 65 parts by weight (trademark: EX10S, manufactured by Mitsubishi Chemical Corporation, resin density 0 (Note) The resin density after compounding is 0.950 g / cc.

Comparative Example 1 The same operation as in Example 1 was performed. However, Composition 8 was prepared and used in place of Composition 2, and the coating amount of Composition 8 was 20 g / m ² to form an undercoat resin coating layer. The results of evaluation performed in the same manner as in Example 1 are shown in the table. Composition 8 Ingredient weight polyethylene resin 65 parts by weight (trademark: LC-500, manufactured by Mitsubishi Chemical Corporation, resin density 0.918 g / cc) 35 parts by weight of polyethylene resin (trademark: HY331, made by Mitsubishi Chemical Corporation, resin density 0 .951g / cc) (Note) Resin density after compounding is 0.930g / cc

Comparative Example 2 The same operation as in Comparative Example 1 was performed. However, an undercoating resin coating layer was formed with the coating amount of the composition 8 being 35 g / m ² . The results of evaluation performed in the same manner as in Example 1 are shown in the table.

Comparative Example 3 The same operation as in Example 1 was performed. However, Composition 9 was prepared and used in place of Composition 2, and the coating amount of Composition 9 was 25 g / m ² to form an undercoat resin coating layer. The results of evaluation performed in the same manner as in Example 1 are shown in the table. Composition 9 Ingredient weight polyethylene resin 75 parts by weight (trademark: LC-604, manufactured by Mitsubishi Chemical Corporation, resin density 0.918 g / cc) polyethylene resin 25 parts by weight (trademark: HY331, made by Mitsubishi Chemical Corporation, resin density 0 (Note) The resin density after compounding is 0.926 g / cc.

Comparative Example 4 The same operation as in Comparative Example 1 was performed. However, an undercoat resin coating layer was formed with the coating amount of the composition 8 being 45 g / m ² . The results of evaluation performed in the same manner as in Example 1 are shown in the table.

[0052]

[Table 1]

The measurement results of curling curl and photographic paper curl in Examples 1 to 8 and Comparative Examples 1 to 4 are shown in the table. From the results in the table, it can be seen that the curl curl and the photographic paper curl change depending on the apparent resin density and the coating amount of the undercoat resin coating layer, and the photographic paper support of Examples 1 to 8 according to the present invention. Are practical for both curl curl and photographic paper curl.

[0054]

EFFECT OF THE INVENTION The photographic printing paper support of the present invention has a curling curl generated during storage, which is a problem when an electron beam cured material is provided on the undercoating resin coating layer.
Further, it is suitable for producing photographic printing paper which is flexible and has excellent surface smoothness and image sharpness by suppressing photographic printing paper curl generated during development processing, and has high practicality.

Claims (2)

(57) [Claims] 1. A paper substrate containing natural pulp as a main component, a subbing resin coating layer formed on one surface of the paper substrate on which a photographic emulsion layer is formed and containing a film-forming synthetic resin as a main component, Formed on the undercoat resin coating layer, and containing an electron beam-curable unsaturated organic compound as a main component,
And at least one surface resin cured layer composed of an electron beam cured product of a coating composition containing titanium dioxide; and a back surface resin formed on the other surface of the paper base and containing a film-forming synthetic resin as a main component. In the photographic printing paper support comprising a coating layer, the film-forming synthetic resin used for the undercoating resin coating layer comprises a polyethylene resin composition containing polyethylene as a main component, and has an apparent resin density of 0.935 to 0. A support for photographic printing paper, which has a weight of 960 g / cc. 2. The coating amount of the polyethylene resin composition is 1
0~35g / m ² at which claim 1 photographic printing paper support as claimed.