JPH06230517A - Base for image material - Google Patents

Abstract

PURPOSE:To obviate the generation of gelatinous foreign matter in a resin layer on the opposite side and to improve the adhesiveness of the resin layer and a base paper and curling property so as to enable high-speed and stable production to be excuted by adopting a specific compd. resin for a polyethylene(PE) resin in the resin layer on the side opposite to the side to be provided with an image forming layer. CONSTITUTION:The difference from the coating amt. of the resin in the resin layer on the side to be provided with the image forming layer is >=3g/m<2> and the PE resin in the resin layer on the opposite side is the compd. resin compsn. which is prepd. by previously melting and mixing 90 to 65 pts.wt. high-density polyethylene resin having 10 to 40g/10 minutes melt flow rate stipulated in JIS (Japanese Industrial Standards) and >=0.960g/cm<3> density and 10 to 35 pts.wt. low-density polyethylene resin or middle-density polyethylene resin having 0.2 to 2g/10 minutes melt flow rate, <=0.935g/cm<3> density, >=10wt.% fraction of >=500000mol.wt. and <=0.5(1/sec) critical shearing speed and has <=10(1/sec) critical shearing speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin-coated support for paper-type image materials in which both sides of a paper substrate (hereinafter referred to as base paper) are coated with a resin composition containing polyethylene resin as a main component, Specifically, the present invention relates to a resin-coated paper-type image material support that has good curl properties and good performance such as adhesion between the base paper and the resin layer on the side opposite to the side on which the image forming layer is provided and that can be stably produced. Is.

[0002]

2. Description of the Related Art Conventionally, a resin-coated paper type support having a base paper surface coated with a resin capable of forming a film has been well known. For example, Japanese Examined Patent Publication (Kokoku) No. 55-12584 discloses a technique for a photographic support in which a base paper is coated with a resin capable of forming a film, preferably a polyolefin resin. U.S. Pat. No. 3,501,298 discloses a technique for a photographic support in which both sides of a base paper are coated with a polyolefin resin. In addition, since the rapid photographic development method of silver halide light-sensitive materials was applied, a photographic support in which both sides of a base paper are coated with a polyethylene resin has been mainly put into practical use for photographic printing paper, If necessary, one resin layer on the image forming side usually contains a titanium dioxide pigment in order to impart sharpness.

US Pat. No. 4,774,224 discloses that the resin coating has a surface roughness of 7.5 microinch-AA.
A thermal transfer recording image-receiving element having the following resin-coated paper, particularly a polyethylene resin-coated paper in which the surface of a base paper is coated with a polyethylene resin, has been proposed. Further, JP-A-63-307979 discloses a technique relating to an ink jet recording sheet having a resin-coated paper as a support.

Further, there has been proposed a technique relating to a photographic support in which the base paper surface opposite to the side on which the photographic layer is provided is coated with a resin composition containing a low density polyethylene resin and a high density polyethylene resin. For example, in JP-B-44-22904, a density of ^{0.915g / cm 3 ~0.926g / cm 3} , a specific low density melting index of 2.9 g / 10 min ~16g / 10 min polyethylene resin 15 wt% to 65 wt% and a density of ^{0.960g / cm 3 ~0.975g / cm 3} , a specific high-density polyethylene resin 85 wt melting index of 5 g / 10 min ~18g / 10 min There is a disclosure of a photographic support coated with a base paper with a polyethylene composition having a high speed coating ability and a good neck-in and pinhole, which is composed of 40 to 35% by weight. Further, Japanese Patent Publication No. 48-9963 discloses low density polyethylene resin: high density polyethylene resin = 1: 1.
There is a disclosure of a photographic support having good curl physical properties, in which a base paper is coated with a resin composition comprising In addition,
58-95732 discloses a high density polyethylene resin having a density of 0.945 g / cm ³ or more, a melt index of 15 to 40 g / 10 minutes, and a density of 0.930 g / cm. ³ or less, melt index 1g
/ 10 minutes-40g / 10 minutes low density polyethylene resin 60
There is a disclosure of a photographic support having good cutting properties and curl physical properties, which is obtained by coating a base paper with a polyethylene resin composition of from 25 to 25 parts by weight.

However, even when the resin composition composed of the low-density polyethylene resin and the high-density polyethylene resin disclosed in these prior arts is used, a support for a resin-coated paper-type image material using a paper substrate is produced. Has been found to cause serious problems.

That is, first, the polyethylene-based resin-coated paper is formed by extruding the molten polyethylene-based resin from a slit die into a film on a base paper which is normally run, casting the melted polyethylene-based resin, and coating it. It is produced by a series of processes in which a pressure roll and a cooling roll are pressure-bonded, and after cooling, they are peeled from the roll. However, when a conventionally known resin composition composed of a low-density polyethylene resin and a high-density polyethylene resin is used, gel-like foreign matter tends to occur on the coated resin surface. The production of polyethylene-based resin-coated paper is carried out by operating the melt extruder continuously for at least 2 to 3 days after starting the operation, usually for 1 week, and sometimes for 1 month, but the continuous operation period can be extended. The higher the degree, the worse the disposition and the more likely this gel-like foreign substance was generated.

[0007] Therefore, the present inventors have pursued the cause of the generation of this gel-like foreign substance. In the first place, when the molten polyethylene resin is extruded and coated on the base paper, the temperature is considerably higher than the melting point of the polyethylene resin. For example, the melting point of low density polyethylene resin is 10
The melting point of the high-density polyethylene resin is about 5 ° C. to 110 ° C., and the melting point of the high-density polyethylene resin is about 120 ° C. to 130 ° C., whereas the melt extrusion temperature from the extrusion die needs to be about 300 ° C. for thin film coating. is there. In general, in the polyethylene molecule, in addition to linear carbon as a polymer of ethylene monomer, unsaturated bonds such as carbon-carbon double bonds,
It is known to contain a methyl group or a side chain carbon having a carbon skeleton bonded thereto. The temperature at around 300 ° C is a moderate temperature from the viewpoint of processing suitability for polyethylene, but it is within the range that promotes activation at the molecular level, and especially during long-term operation, factors such as flow change of molten polyethylene resin As a result, radicals are easily generated in the vicinity of unsaturated bonds in the molecule and side chain carbons, the radicals cause a chain reaction and the molten polyethylene resin causes a cross-linking reaction to accumulate and stay inside the extruder. However, it has come to be considered that when it is extruded together with the film, it appears as a gel-like foreign substance.

When this gel-like foreign substance starts to be produced during the production of the resin-coated paper, the resin in the coating becomes streaky and thin,
At times, there was a serious problem that resin cracking occurred and uniform resin-coated paper could not be obtained. Further, in the support for image material in which both sides of the base paper are coated with a resin layer containing a polyethylene resin as a main component, the side opposite to the side on which the image forming layer is provided (hereinafter, simply abbreviated as front side) (hereinafter, simply If gel-like foreign matter is present in the coating resin on the back side)
The appearance of the image material itself having the support is impaired and the commercial value is lost. In particular, when a gel-like foreign substance is generated in the resin layer on the back side (hereinafter simply referred to as the back resin layer), an image forming layer, particularly silver halide, is formed on the resin layer on the front side (hereinafter simply referred to as the front resin layer). When coating the photographic component layers, the influence from the back side causes uneven coating, which makes it impossible to coat the image forming layers uniformly, which is a serious problem in that it causes a fatal quality failure. . For this reason, it has been necessary to take sufficient measures to prevent gel-like foreign matter.

As a method of preventing the generation of such a gel-like foreign substance, there is a method of operating by lowering the extrusion processing temperature, but in that case, the adhesiveness between the polyethylene resin and the paper is lowered, so that it is necessary. In order to maintain the adhesiveness, the processing speed is limited and the productivity is reduced. Further, although disassembling and cleaning the extruder in a short cycle is effective, it is inevitable that the productivity is lowered. Further, the study by the present inventors has revealed that adding an antioxidant to the polyethylene resin composition is effective to some extent in preventing this gel-like foreign matter, but a large amount of antioxidant It is necessary to add an agent, and in this case, there arises a problem that the adhesiveness between the base paper and the resin layer becomes extremely insufficient.
In particular, when the base paper is produced under a high speed condition of 150 m / min or more, there is a problem that the adhesiveness between the base paper and the resin layer is further deteriorated.

Secondly, the polyethylene resin-coated paper as a support for image materials is required to have excellent surface resin surface smoothness. On the other hand, the texture, feel, and waist of the image material are required. Therefore, a support having a weight that meets the user's standard is desired. The most effective way to improve the smoothness of polyethylene resin coated paper is to increase the coating amount of the surface resin layer, but to reduce the basis weight of the base paper for the increase of the coating amount of the surface resin layer. Therefore, it is preferable to select the method of reducing the coating amount of the back resin layer because the above-mentioned properties such as texture, feel, and waist are significantly deteriorated. However, in this case, the image material using the resin-coated paper as a support curls toward the image forming layer side, and there is a problem that handling becomes extremely inconvenient. Further, the smaller the coating amount of the back resin layer, the worse the adhesiveness between the base paper and the resin layer. The problem of the adhesiveness between the base paper and the resin layer became more obvious as the running speed of the base paper increased.

[0011]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to prevent gel-like foreign matters from being generated in the resin layer on the side opposite to the side on which the image forming layer is provided, and to provide the resin layer and the base paper. Good adhesion, and good performance such as curl physical properties,
It is another object of the present invention to provide a support for a resin-coated paper-type image material, which can be produced at a high speed and can be stably produced, and has both sides of which are coated with a resin composition containing a polyethylene resin as a main component, the substrate being paper. Other objects of the present invention will be apparent from the description below.

[0012]

Means and Actions for Solving the Problems As a result of intensive studies by the present inventors in order to solve the above-mentioned problems, as a result, a resin comprising a resin composition containing polyethylene resin as a main component on both sides of a paper substrate. The difference between the coating amount of the resin in the resin layer on the side on which the image forming layer is provided and the coating amount of the resin on the side opposite to the side on which the image forming layer is provided in the support for image material coated with the layer. Is 3 g / m ² or more, and the polyethylene resin in the resin layer on the side opposite to the side on which the image forming layer is provided is J
The melt flow rate specified by IS K 6760 is 1
0 g / 10 minutes to 40 g / 10 minutes, 90 parts by weight to 65 parts by weight of high-density polyethylene resin having a density of 0.960 g / cm ³ or more, and a melt flow rate specified by JIS K 6760 of 0.2 g / 10 minutes. Low density polyethylene resin or medium having a density of 0.935 g / cm ³ or less, a molecular weight of 500,000 or more, a fraction of 10% by weight or more, and a critical shear rate of 0.5 (1 / sec) or less Density polyethylene resin 10 parts by weight to 3
5 parts by weight of a compound resin composition prepared in advance by melting and mixing, and a resin-coated paper-type image material support in which the critical shear rate of the compound resin is 10 (1 / sec) or less, It has been found that the object of the invention is achieved. The critical shear rate of resin here is the cone
It is the shear rate (unit: 1 / sec) at the point where the difference between the shear stress measured at 240 ° C. and the first normal stress is equal using a plate-type rotary viscometer. In addition, the melt resin of the low density polyethylene resin or the medium density polyethylene resin has a melt flow rate of 0.2 g / 10 minutes or more and less than 1 g / 10 minutes,
It has been found that the object of the present invention can be achieved more remarkably.

The high density polyethylene resin for the back resin layer used in the practice of the present invention has a density of 0.960 g /
cm ³ or more, and has a melt flow rate defined by JIS K 6760 (hereinafter, the melt flow rate defined by JIS K 6760 is simply referred to as MFR).
If it is in the range of 0 g / 10 minutes to 40 g / 10 minutes and the critical shear rate of the resin composition when prepared into a compound resin composition is 10 (1 / sec) or less, Various densities, MFRs, molecular weights, and molecular weight distributions can be used alone or as a mixture, and ordinary high-density polyethylene resins, ethylene and propylene, butylene, α-
Various materials such as copolymers with olefins and mixtures thereof can be used.

The low-density polyethylene resin or medium-density polyethylene resin of the back resin layer used in the practice of the present invention has a density of 0.935 g / cm ³ or less and an MFR of 0.
It is in the range of 2 g / 10 min to 2 g / 10 min, the fraction with a molecular weight of 500,000 or more is 10 wt% or more, and the critical shear rate is 0.5.
(1 / sec) or less, and the critical shear rate of the resin composition when prepared into a compound resin composition is 1
If it is less than 0 (1 / second), various densities, M
FR, molecular weight and molecular weight distribution compounds can be used alone or in combination. For example, high-pressure low-density polyethylene resin (autoclave low-density polyethylene resin, tube
Bra method low density polyethylene resin), linear low density polyethylene resin, medium density polyethylene resin, copolymers of ethylene and α-olefins such as propylene and butylene, carboxy-modified polyethylene resin and mixtures thereof. Can be used.

Use ratio, density, MFR of low density polyethylene resin or medium density polyethylene resin and high density polyethylene resin of the back resin layer used in the practice of the present invention
And the critical shear rate, the mixing properties of the resin when producing the support for image materials, molding processability, the effect of preventing gel foreign matter and the adhesiveness between the base paper of the support for image materials and the resin composition layer, The present invention has been made based on the results of a trial and error experiment and the comprehensive knowledge of the curl physical properties, cuttability, feel to the touch, performance as a support for image materials such as waist, and the like. .
In particular, the amount of the high-density polyethylene resin used in the resin composition comprising the high-density polyethylene resin and the low-density or medium-density polyethylene resin is 90 parts by weight to 65 parts by weight, preferably 85 parts by weight to 70 parts by weight. It is a range of parts. If the amount of the resin used is less than 65 parts by weight, the curl physical properties, cuttability, stiffness and the like of the support for image materials will be deteriorated, and if it is more than 90 parts by weight, the mixing property of the resin and the molding process will occur. And the adhesiveness between the base paper and the resin layer deteriorates, which is a problem.

The MFR of the high density polyethylene resin for the back resin layer used in the practice of the present invention is 10 g / 10.
Min to 40 g / 10 min, preferably 10 g / 10 min
It is in the range of 30 g / 10 minutes. If the MFR of the resin is lower than 10 g / 10 min, the adhesiveness between the base paper and the resin layer and high-speed processability will be deteriorated, and if it is higher than 40 g / 10 min, the mixing property and molding processability of the resin will be caused. And the like, and the physical properties of the curl tend to be poor, which is a problem. Further, the density of the high-density polyethylene resin is 0.960 g / cm ³ or more, but if the density is lower than 0.960 g / cm ³ , there is a problem that curl physical properties, stiffness and the like deteriorate, and it is preferable. It is 0.962 g / cm ³ or more.

On the other hand, the MFR of the low density polyethylene resin or the medium density polyethylene resin of the back resin layer used in the practice of the present invention is in the range of 0.2 g / 10 min to 2 g / 10 min, but 0.2 g / min. If it is less than 10 minutes, the mixing property of the resin, the adhesiveness between the base paper and the resin layer, the high-speed processability and the like are deteriorated, and if it is more than 2 g / 10 min, the molding processability is deteriorated and the curl is deteriorated. The physical properties tend to be poor, which is a problem, and preferably 0.2
It is in the range of g / 10 minutes to less than 1 g / 10 minutes. The density of the low-density polyethylene resin or the medium-density polyethylene resin is 0.935 g / cm ³ or less, and the density is 0.935 g.
If it is higher than 0.13 / cm ³ , there is a problem that the molding processability of the resin composition and the adhesiveness between the base paper and the resin layer are deteriorated, and it is preferably 0.
It is 930 g / cm ³ or less. The fraction of the resin having a molecular weight of 500,000 or more is 10% by weight or more, preferably 12% by weight or more. If the fraction of the resin having a molecular weight of 500,000 or more is less than 10% by weight, molding processability, especially neck-in becomes large, which is a problem. Here, the molecular weight is measured by Waters 150-C (column: Tosoh G
MH-XL HT 8mmφ × 30cm × 3, solvent: 1,
2,4-trichlorobenzene, temperature: 135 ° C, flow rate:
It was performed by the GPC method using 1 ml / min). Next, the critical shear rate of the resin is 0.5 (1 / sec) or less, preferably 0.4 (1 / sec) or less. When the critical shear rate is higher than 0.5 (1 / sec), there are problems such as moldability and generation of gel-like foreign matter. Here, the critical shear rate is measured by a cone-plate type rotary viscometer (a rheometric mechanical spectrometer manufactured by Rheometric Co., a cone-plate diameter: 25 mm, an angle: 0.1 ra).
d, temperature: 240 ° C.), and in FIG.
The shear rate at the point where the difference between the shear stress and the first radiation stress is equal was defined as the critical shear rate (unit: 1 / sec).

The polyethylene resin of the back resin layer used in the practice of the present invention is used as a compound resin prepared by melting and mixing in advance. As a method for preparing a compound resin by previously melting and mixing a low-density polyethylene resin or a medium-density polyethylene resin and a high-density polyethylene resin, a simple melt mixing method, a multistage melt mixing method, or the like can be used. For example, an extruder, a twin-screw extruder, a heating roll kneader, a Banbury mixer, a pressure kneader.
A predetermined amount of low- or medium-density polyethylene resin and high-density polyethylene resin, and if necessary, various additives such as antioxidants and lubricants are added, melted and mixed, and then the mixture. The method of pelletizing is preferably used. When the polyethylene resin is not used as the compound resin and is directly added to the melt extrusion machine in the state of simple mixing and melt extrusion coated,
This is a problem because the adhesiveness between the base paper and the resin layer, the mixing properties of the resin, the molding processability, etc. deteriorate.

The critical shear rate of the compound resin used in the practice of the present invention is 10 (1/1 / th) in order to prevent gel-like foreign matter generated over time during extrusion melt coating. Seconds or less, preferably 8 (1 / second) or less. When the critical shear rate is higher than 10 (1 / sec), gel-like foreign matter is generated, which is a problem. The effect of preventing the occurrence of gel foreign matter according to the present invention is considered to be due to the viscoelastic property of the resin at a high resin temperature during melt extrusion coating, and the property of the resin is viscous at the critical shear rate. It is considered that since it becomes elastic, it is manifested by reducing the chance of gelation, crushing gel and improving kneading.

The base paper of the support for image materials in the present invention
The surface on which the image forming layer is provided is mainly made of polyethylene resin.
It is coated with a resin composition as a component. Those politics
As ren resin, low density polyethylene resin, medium density
Polyethylene resin, high density polyethylene resin, linear low
Density polyethylene resin, ethylene and propylene, butyr
Copolymers with α-olefins such as
Use various materials such as polyethylene resin and their mixtures.
Can be used. Also, various density, MFR, molecular weight, molecular weight
A distribution can be used, but the density is usually 0.91 g / cm³ 
~ 0.97 g / cm ³Range, MFR 1g / 10min-30g / 10
Min, molecular weight in the range of 20,000 to 250,000 alone or
It can be mixed and advantageously used.

In the image material support of the present invention, the difference between the coating amount of the resin in the front resin layer and the coating amount of the resin in the back resin layer is preferably 3 g / m ² or more. There is no limitation, but 5 g / m ² or more is preferable, and 7 g / m ² or more is particularly preferable. If the difference between the resin coating amounts on the front and back is less than 3 g / m ² , the image material having the resin-coated paper as a support curls on the opposite side of the image forming layer, and its handling becomes extremely inconvenient. This is a problem, and moreover, there is a problem that the cutting property of the support for image material or the image material having the support for image material is deteriorated. That is, a support for an image material or an image material having the support for an image material is a guillotine cutter or a precision print cutter (precision precision cutter).
It is cut into a desired size with a cutter such as an nt cutter), but at that time the image material support is not cut accurately, and a whisker-like thing is generated from the cut surface of the image material support, so that the commercial value However, the cut surface is good in the image material support or the image material having the image material support of the present invention.

The image material support in the present invention is a so-called melt-extrusion coater in which a polyethylene resin composition is cast on a running base paper in a film form from its slit die by using a melt-extrusion machine. Manufactured by the Ting method. At that time, the temperature of the molten film is 280
C. to 340.degree. C. is preferable. The slit die is preferably a T-type die, an L-type die, or a fishtail type die, and the slit opening diameter is preferably 0.1 mm to 2 mm. Before coating the resin composition on the base paper, it is preferable to subject the base paper to an activation treatment such as corona discharge treatment or flame treatment. Further, as described in JP-B-61-42254, a resin layer may be coated on the running base paper after the ozone-containing gas is blown to the molten resin composition on the side in contact with the base paper. The resin layers on the front and back sides are preferably extruded and coated on the base paper sequentially, preferably continuously by a so-called tandem extrusion coating method. You may coat | cover by the multilayer extrusion coating system which makes a resin layer into a multilayer structure of two or more layers. Also, the surface resin layer surface of the support for image materials can be processed into a glossy surface, a finely rough surface described in Japanese Patent Publication No. 62-19732, a matte surface or a silk surface, and the back resin layer is usually matte. It is preferable to process the surface. The thickness of the front and back resin layers is not particularly limited as long as the difference in resin coating amount between the front and back resin layers is 3 g / m ² or more, but the thickness of the front and back resin layers is not limited. As a matter of fact, 9μ
A range of m to 100 μm is useful, preferably 12 μm.
It is in the range of m to 55 μm. As the thickness of the back resin layer,
A range of 5 μm to 95 μm is useful, but preferably 8
It is in the range of μm to 50 μm.

Various additives can be contained in the front and back resin layers of the support for image materials in the present invention. Japanese Patent Publication No. 60-3430, Japanese Patent Publication No. 63-11655, 1-382
No. 91, Japanese Examined Patent Publication No. 1-38292, and titanium oxide, zinc oxide, talc described or exemplified in each publication such as JP-A-1-105245.
White pigments such as calcium carbonate, fatty acid amides such as stearic acid amide and arachidic acid amide, fatty acid metal salts such as zinc stearate, calcium stearate, aluminum stearate, magnesium stearate, zinc palmitate, zinc myristate, calcium palmitate. , Hinder described or exemplified in JP-A-1-105245
Various antioxidants such as dophenol, hindered amine, phosphorus-based and sulfur-based, cobalt-blue, ultramarine blue, cerian blue, phthalocyanine blue and other blue-based pigments and dyes,
Magenta pigments and dyes such as cobalt violet, fast violet and manganese violet.
Various additives such as fluorescent whitening agents and ultraviolet absorbers described or exemplified in JP-A-254440 can be appropriately combined and contained. These additives are preferably included as a master-batch or compound of the resin. In particular, as a method of incorporating these additives in the compound resin composition for the back resin layer used in the practice of the present invention, high-density polyethylene resin and low-density polyethylene resin or medium-density polyethylene resin is added in advance, Alternatively, it may be added at the time of preparation of the compound resin, or a masterbatch added to the resin at a high concentration may be prepared in advance, and this masterbatch may be added to the resin at the time of melt extrusion coating.

The base paper used for carrying out the present invention is preferably a natural pulp paper containing normal natural pulp as a main component (hereinafter, a base paper containing natural pulp as a main component is simply referred to as base paper). Further, mixed paper made of natural pulp and synthetic pulp, synthetic fiber, so-called synthetic paper made of synthetic pulp, synthetic fiber or synthetic resin film may be used. The thickness of the base paper is not particularly limited, but the basis weight is 40
Preferably those g / m ² ~250g / m ²

Pulp constituting the base paper preferably used in the practice of the present invention is described in JP-A-58-37642 and JP-A-60.
It is advantageous to use an appropriately selected natural pulp as described or exemplified in each of JP-A-67940, JP-A-60-69649 and JP-A-61-35442. Natural pulp was subjected to usual bleaching treatment such as chlorine, hypochlorite, chlorine dioxide bleaching, alkali extraction or alkali treatment and, if necessary, oxidative bleaching treatment with hydrogen peroxide, oxygen, etc., and a combination thereof. Wood pulp such as softwood pulp, hardwood pulp and mixed wood of hardwood and hardwood is advantageously used, and various kinds of pulp such as kraft pulp, sulfite pulp and soda pulp can be used.

The base paper preferably used in the practice of the present invention may contain various additives at the time of preparing the stock slurry. As the sizing agent, fatty acid metal salt and / or fatty acid, alkyl ketene dimer emulsion or epoxidized higher fatty acid amide, alkenyl or alkyl succinic anhydride emulsion, rosin derivative and the like described or exemplified in JP-B-62-7534. As a dry paper strength enhancer, anionic, cationic or amphoteric polyacrylamide, polyvinyl alcohol, cationized starch, vegetable galactomannan, etc., as a wet paper strength enhancer, polyamine polyamide epichlorohydrin resin, etc., as a filler, clay, Kaolin, calcium carbonate, titanium oxide, etc. as a fixing agent, water-soluble aluminum salts such as aluminum chloride and vanadium sulfate, etc., and caustic soda as a pH adjuster.
Da, soda carbonate, sulfuric acid, etc., etc. JP-A-63-204251
Advantageously, the color pigments, color dyes, optical brighteners and the like described or exemplified in JP-A 1-266537 and the like are contained in an appropriate combination.

The base paper preferably used for carrying out the present invention may contain various water-soluble polymers, antistatic agents and additives by a spray or tab size press. As a water-soluble polymer, JP-A-1-
Starch-based polymers, polyvinyl alcohol-based polymers, gelatin-based polymers described or exemplified in JP-A-266537.
Polyacrylamide type polymer, Cellulose type polymer
As an antistatic agent, alkali metal salts such as sodium chloride and potassium chloride, alkaline earth metal salts such as calcium chloride and barium chloride, colloidal metal oxides such as colloidal silica, and organic electrification such as polystyrene sulfonate. Emulsions and latexes such as inhibitors, emulsions or latexes of ethylene-vinyl acetate copolymer, petroleum resin emulsions, etc., pigments such as clay, kaolin, talc, barium sulfate, titanium oxide, etc., and pH regulators such as hydrochloric acid. , Phosphoric acid, citric acid, caustic soda, etc., as well as the above-mentioned color pigments, coloring dyes, optical brighteners and the like, are preferably combined in an appropriate combination.

The base paper preferably used in the practice of the present invention is preferably one having a smooth surface having a Bekk smoothness of 100 seconds or more as defined by JIS P8119.
Those having a smooth surface of 200 seconds or more are more preferable. As a method for producing a base paper having a Beck's smoothness of 100 seconds or more, generally, a hardwood pulp, which is short fiber and easy to smooth, is used in a large amount and beaten with a beater so that the long fiber content is reduced as much as possible. Specifically, the beating of the pulp is such that the fiber length of the beating pulp is 42 mesh with the residual content of 20 to 45.
%, The freeness is preferably 200 to 350 CSF. Next, a paper chiller containing internal additives
With regard to the paper making machine, a fourdrinier paper machine is adopted by using an appropriate paper making method as described or exemplified in each of Japanese Patent Laid-Open Nos. 58-37642, 61-260240 and 61-284762. , Papermaking with a paper machine normally used such as a cylinder paper machine so that a uniform formation is obtained, and further, after the papermaking, a machine calendar, a
It is possible to produce a base paper having a Beck smoothness of 100 seconds or more by carrying out a calendering treatment using a calender or a thermal calender.

The surface of the surface resin layer of the support for image material in the present invention is subjected to activation treatment such as corona discharge treatment and flame treatment, and then, JP-A-61-84643 and JP-A-1-92740,
An undercoat layer as described or exemplified in JP-A-1-102551, JP-A-1-66035 and the like can be coated.
Further, on the back resin layer surface of the support for image material in the present invention, various back coat layers are coated on the surface of the backing resin layer for the purpose of preventing electrification after activation treatment such as corona discharge treatment and flame treatment. be able to. In addition, in the back coat layer, Japanese Patent Publication Nos. 52-18020, 57-9059, 57-53940,
JP-B-58-56859, JP-A-59-214849, JP-A-58-1841
Inorganic antistatic agent described or exemplified in each publication such as No. 44,
An organic antistatic agent, a hydrophilic binder, a latex, a curing agent, a pigment, a surfactant and the like can be contained in an appropriate combination.

The support for image materials in the present invention is coated with various photographic constituent layers and is used for color photographic printing paper, black-and-white photographic printing paper, typesetting photographic paper, copy photographic paper, reversal photographic material. , Silver salt diffusion transfer method, negative and positive, and printing materials. For example, silver chloride, silver bromide, silver chlorobromide, silver iodobromide, and silver chloroiodobromide emulsion layers can be provided. The silver halide photographic emulsion layer can contain a color coupler to provide a multilayer silver halide color photographic constituent layer. Further, a photographic constituent layer for silver salt diffusion transfer method can be provided. As the binder for the photographic constituent layers, in addition to ordinary gelatin, hydrophilic polymer substances such as polyvinylpyrrolidone, polyvinyl alcohol, and sulfate ester compounds of polysaccharides can be used. Further, the above-mentioned photographic constituent layers can contain various additives. For example, as sensitizing dyes, cyanine dyes, merocyanine dyes, etc., as chemical sensitizers, water-soluble gold compounds, sulfur compounds, etc., antifoggants or stabilizers, hydroxy-triazolopyrimidine compounds, mercapto-heterocyclic compounds, etc. , Hardener, formalin, vinyl sulfone compound, aziridine compound, etc., coating aid, alkylbenzene sulfonate, sulfosuccinic acid ester salt, etc., anti-fouling agent, dialkyl hydroquinone compound, etc., optical brightener, sharpness improvement Dye, antistatic agent, pH adjusting agent,
A fogging agent and a water-soluble iridium or water-soluble rhodium compound may be appropriately combined and contained during the production and dispersion of the silver halide.

The photographic material according to the present invention is exposed, developed and stopped as described in "Photosensitive material and handling method" (Kyoritsu Shuppan, Goro Miyamoto, Photographic Engineering Course 2) according to the photographic material. , Fixing, bleaching, stabilizing, etc. can be performed. The multilayer silver halide color photographic material may be processed with a developing solution containing a development accelerator such as benzyl alcohol, thallium salt or phenidone, or may be processed with a developing solution containing substantially no benzyl alcohol. it can.

The support for image material in the present invention can be used as a support for various heat transfer recording image receiving materials by coating various heat transfer recording image receiving layers. As the synthetic resin used for the thermal transfer recording image-receiving layer, a resin having an ester bond such as a polyester resin, a polyacrylic ester resin, a polycarbonate resin, a polyvinyl acetate resin, a polyvinyl butyral resin, a styrene acrylate resin, or a vinyl toluene acrylate resin. , Resins having urethane bonds such as polyurethane resins, resins having amide bonds such as polyamide resins, resins having urea bonds such as urea resins, other polycaprolactam resins, styrene resins, polyvinyl chloride resins, vinyl chloride-vinyl acetate Examples thereof include copolymer resins and polyacrylonitrile resins. In addition to these resins, mixtures or copolymers thereof can be used.

In the thermal transfer recording image-receiving layer according to the present invention,
In addition to the above synthetic resin, a release agent, pigment or the like may be added. Examples of the releasing agent include solid waxes such as polyethylene wax, amide wax, and Teflon powder, fluorine-based waxes,
Examples thereof include phosphate ester type surfactants and silicone oils. Among these release agents, silicone oil is most preferable. An oily substance can be used as the silicone oil, but a curable type is preferable. Examples of the curable silicone oil include a reaction curable type, a photocurable type and a catalyst curable type, and a reaction curable type silicone oil is particularly preferable. Examples of the reaction-curable silicone oil include amino-modified silicone oil and epoxy-modified silicone oil. The amount of the reactive silicone oil added is preferably 0.1 to 20 wt% in the image receiving layer. As the pigment, extender pigments such as silica, calcium carbonate, titanium oxide and zinc oxide are preferable. Further, the thickness of the image receiving layer is preferably 0.5 to 20 μm,
10 μm is more preferable.

The support for image materials in the present invention can be used as a support for various ink jet recording materials by coating various ink receiving layers. Various binders may be contained in these ink receiving layers for the purpose of improving the drying property of the ink and the sharpness of the image. Specific examples of these binders include lime-processed gelatin, acid-processed gelatin, enzyme-processed gelatin, gelatin derivatives, and various gelatins such as gelatin reacted with an anhydride of a dibasic acid such as phthalic acid, maleic acid and fumaric acid. , Ordinary polyvinyl alcohol with various degrees of saponification,
Carboxy-modified, cation-modified and amphoteric polyvinyl alcohols and their derivatives, oxidized starch, cationized starch, etherified starch and other starches, carboxymethyl cellulose, hydroxyethyl cellulose and other cellulose derivatives, polyvinylpyrrolidone, polyvinylpyrrolidone. Dihalide, sodium polyacrylate, acrylic acid methacrylic acid copolymer salt, polyethylene glycol, polypropylene glycol, polyvinyl ether, alkyl vinyl ether / maleic anhydride copolymer, styrene / maleic anhydride copolymer and salts thereof, polyethylene Synthetic polymers such as imines, styrene-butadiene copolymers, conjugated diene-based copolymer latex such as methylmethacrylate-butadiene copolymers, polyvinyl acetate, vinyl acetate
Vinyl acetate polymer latex such as maleic acid ester copolymer, vinyl acetate / acrylic acid ester copolymer, ethylene / vinyl acetate copolymer, acrylic acid ester polymer, methacrylic acid ester polymer, ethylene / acrylic acid ester Acrylic polymer or copolymer latex such as copolymer, styrene / acrylic acid ester copolymer, vinylidene chloride copolymer latex, etc. or a functional group-containing unit such as carboxyl group of these various polymers Functional group-modified polymer latex by body, water-based adhesive such as thermosetting synthetic resin system such as melamine resin, urea resin and polymethylmethacrylate, polyurethane resin, unsaturated polyester resin, vinyl chloride / vinyl acetate copolymer, polyvinyl butyral, Synthetic resin adhesive such as alkyd resin, Japanese Patent Publication No. 3-24906 No. 3-281383, Japanese Patent Application No. 4-2
Examples thereof include inorganic binders such as alumina sol and silica sol described or exemplified in each publication such as 40725, and these may be contained alone or in combination.

The ink receiving layer of the ink jet recording material according to the present invention may contain various additives in addition to the binder. For example, as the surfactant, a long-chain alkylbenzene sulfonate, an anionic surfactant such as a long-chain, preferably branched alkylsulfosuccinate ester salt, a long-chain, preferably a polyalkylene oxide of a branched alkyl group-containing phenol Nonionic surfactants such as ethers and polyalkylene oxide ethers of long-chain alkyl alcohols, JP-B-47-9303
Silane coupling agents such as γ-aminopropyltriethoxysilane and N-β (aminoethyl) γ-aminopropyltrimethoxysilane, such as fluorinated surfactants described in U.S. Pat. As a polymer hardener, active halogen compounds, vinyl sulfone compounds, aziridine compounds, epoxy compounds,
As hardeners and preservatives such as acryloyl compounds and isocyanate compounds, P-hydroxybenzoic acid ester compounds, benzisothiazolone compounds, isothiazolone compounds, etc. described or exemplified in JP-A-1-102551, JP-A-63-204251 , Color pigments described in each publication such as JP-A 1-266537 or exemplified, coloring dyes, optical brighteners, etc.,
Sodium hydroxymethanesulfonate, sodium P-toluenesulfinate, etc., as an anti-yellowing agent, a benzotriazole compound having a hydroxy-di-alkylphenyl group at the 2-position as an ultraviolet absorber, an antioxidant, etc. As a pencil writing agent such as the polyhindered phenol compound described or exemplified in 105245, starch particles, barium sulfate, silicon dioxide, and other organic or inorganic fine particles having a particle diameter of 0.2 μm to 5 μm, Japanese Patent Publication No. 4-1337. Organopolysiloxane compounds described or exemplified in the publication, etc., as a pH adjusting agent, various additives such as caustic soda, sodium carbonate, sulfuric acid, hydrochloric acid, phosphoric acid, citric acid, etc., octyl alcohol, silicon antifoaming agents, etc. are appropriately combined. Can be included.

[0036]

EXAMPLES In order to describe the present invention more specifically,
Examples will be described.

Example 1 A mixture of 1: 1 hardwood bleached sulfite pulp and 1: 1 hardwood bleached kraft pulp was beaten to 320 ml of Canadian standard freeness, and 100 parts by weight of pulp was mixed with 3 parts of chaotic starch. Parts by weight, 0.2 parts by weight of anionized polyacrylamide, 0.4 parts by weight of alkyl ketene dimer-emulsion (as ketene dimer content), and 0.4 parts by weight of polyaminopolyamide epichlorohydrin resin, and a basis weight of 160 g / m ² Paper was manufactured. The obtained wet paper is dried at 110 ° C., and subsequently, 3 parts by weight of carboxy-modified polyvinyl alcohol, 0.05 part by weight of optical brightener, 0.002 part by weight of blue dye, 4 parts by weight of sodium chloride, 0 part of citric acid. 2 parts by weight and 93 parts by weight of water were impregnated with 25 g / m ^{2 of} impregnating liquid, dried with hot air at 110 ° C., and further supercalendered at a linear pressure of 90 kg / cm to prepare a photographic support. A base paper was manufactured. At this time, the Bekk smoothness of the base paper was 200 seconds.

Next, after the base paper surface (rear surface) opposite to the side on which the image forming layer is coated is subjected to corona discharge treatment, the polyethylene resin composition shown in Table 1 is applied to the rear surface at a resin temperature of 320 ° C.
Then, the resin coating amount shown in Table 1 was melt extrusion coated at a running speed of the base paper of 150 m / min.

Subsequently, the surface of the base paper was subjected to corona discharge treatment, and then a low density polyethylene resin (density 0.92) was applied to the surface.
0 g / cm ³ , MFR = 8.5 g / 10 min) 47.5% by weight, aluminum oxide hydroxide (vs titanium dioxide to Al ₂ O ₃
50% by weight of anatase titanium dioxide pigment surface-treated with 0.75% by weight) and zinc stearate 2.5
Titanium dioxide pigment master batch 20% by weight
Parts by weight, low-density polyethylene resin (density 0.920 g / cm
^3, MFR = 4.5g / 10 min) 65 parts by weight of a high density polyethylene resin (density ^{0.970g / cm 3, MFR = 7.0g} / 1
0 minutes) A resin composition consisting of 15 parts by weight was added to a resin temperature of 320
The running speed of the base paper is 150m /
Melt extrusion coated in minutes. The melt extrusion coating of the front and back polyethylene resins was performed by a so-called tandem system in which extrusion coating was sequentially performed. At that time, the surface of the resin layer containing the titanium dioxide pigment of the resin-coated paper was processed into a glossy surface, and the surface quality of the back resin layer was processed into a matte surface such as paper.

Further, the back resin layer surface of the resin-coated paper was subjected to corona discharge treatment, and then the following back coat coating liquid was applied on-machine. As a dry weight, a backcoat coating solution containing colloidal silica: styrene latex = 1: 1 and further containing 0.021 g / m ² of sodium polystyrene sulfonate and an appropriate amount of a coating aid is used as a latex content (solid content). (By weight calculation)
Was applied at a coating amount of 0.21 g / m ² to obtain a support for image materials. I worked.

Molding processability of the polyethylene resin composition for the backside resin layer when producing the image material support as described above, the degree of generation of gel-like foreign matter, and the sample support for the image material obtained As a method of evaluating the performance as
It evaluated by the method as described below.

As a method for evaluating the moldability of the polyethylene resin composition for the back resin layer in the production of the support for image materials, the lateral length of the resin coating portion on the back surface is measured to determine the degree of neck-in. In addition to the evaluation, the degree of streaking of the molten resin film, the presence or absence of film breakage depending on the degree of drawdown property, and the molding processability such as flow instability due to surging or draw resonance were evaluated comprehensively. As the evaluation criteria, ◯ is good, Δ is a little bad, but there is no problem in practical use, and X is bad, there is a problem in practical use to some extent.

As a method for evaluating a gel-like foreign substance during melt extrusion of a polyethylene resin composition for a back resin layer, a set temperature of 320 ° C. and a condition of 2.5 kg per hour are used.
The gel-like foreign matter was evaluated by measuring the number of gel-like foreign matter of 0.1 mm or more in the 0.01 m ² film after extruding into a film shape and comparing it with the initial value. As the evaluation criteria, ◯: the number of gel-like foreign matters after 8 hours was not changed from the initial value, Δ: the number of gel-like foreign matters after 8 hours was slightly increased, but there was no problem in practical use,
Poor: The number of gel-like foreign substances after 8 hours increased more than the initial value, indicating a problem in practical use to some extent.

As a method for evaluating the adhesiveness between the base paper and the back resin layer of the support for image material, each sample was tested at 50 ° C. and 60% RH.
After storing it in the constant temperature and humidity chamber for 1 day, peel off the base paper layer and the resin layer on the back side of the sample, and measure the area ratio of the base paper layer adhered to the peeled resin layer, The adhesiveness with the resin layer was evaluated. As an evaluation standard, ○; area ratio is 10
0% is good, Δ: Area ratio is less than 100% and 80% or more, adhesiveness is a little bad, but practically no problem, ×;
The area ratio is less than 80%, which means that the adhesiveness is poor and there are some practical problems.

The curl physical properties of the support for image materials were evaluated as follows. First, a blue-sensitive emulsion layer containing a yellow color coupler after corona discharge treatment on the resin surface on the front side containing a titanium dioxide pigment of a support for image materials, an intermediate layer containing a color mixing inhibitor, and a green color containing a magenta color coupler. A color photographic paper having a total amount of gelatin of 8 g / m ² was prepared by providing an emulsion layer, an ultraviolet absorber layer containing an ultraviolet absorber, a red emulsion layer containing a cyan color coupler and a protective layer. Each color-sensitive emulsion layer contains silver chlorobromide equivalent to 0.6 g / m ² in terms of silver nitrate. In addition to gelatin necessary for the formation, dispersion and film formation of silver halide, an appropriate amount of antifoggant and sensitizing dye. , Coating aids, hardeners, thickeners and suitable amounts of filter dyes and the like. Next, the prepared color photographic paper was stored at 35 ° C. and normal humidity for 5 days, and after color development, color printing of a size of 8.2 cm × 11.7 cm at 20 ° C. and 40% RH was performed. -The condition of the le was evaluated. As the evaluation criteria, ○: a little minus curl (curl to the back coat layer side) and extremely flat, curl physical properties are good, Δ: curl is present,
It shows that there is no problem in practical use, x; the curl is large and there is a problem in practical use to some extent.

As a method for evaluating the cuttability of the support for image material, the above color photographic paper is cut into a size of 11.7 cm in the length direction with a precision print cutter, and the state of the cut surface is cut. Was evaluated. As an evaluation standard,
◯: Almost no beards and good cutting performance, Δ: Slight beards were generated, but there was no problem in practical use, ×: Many beards were generated and cutting performance was poor, and there were some practical problems. Represents

The smoothness of the support for image materials was evaluated by observing the surface of the above color photographic paper with oblique light and visually evaluating the glossiness. As the evaluation criteria, ○: the appearance has a high glossiness and the smoothness of the support is good, Δ: the appearance has a slightly low glossiness, the smoothness of the support is slightly inferior, but there is no problem in practical use, × The appearance is low in glossiness, the smoothness of the support is poor, and there is a practical problem.

The results obtained are shown in Table 1.

[0049]

[Table 1]

Note that (Note 1) to (Note 4) in Table 1 are as follows.

(Note 1) ○ represents a sample according to the present invention.

(Note 2) HDPE; density 0.967 g / c
m ^3, MFR = 15g / 10 min high density polyethylene resin.

(Note 3) LDPE; density 0.924 g / c
m ³ , MFR = 0.6 g / 10 min, fraction with molecular weight of 500,000 or more =
Low density polyethylene resin with 15% by weight and critical shear rate = 0.06 (1 / sec).

(Note 4) Method for preparing polyethylene resin composition-compound; used as pellets of compound resin prepared by previously melting and mixing HDPE and LDPE with an extruder for kneading. Simple mixing; HDPE
And LDPE are simply mixed and added to the melt extruder for use.

From the results shown in Table 1, the difference between the resin coating amounts in the front and back resin layers was 3 g / m ² or more, and the polyethylene resin in the back resin layer was 90% by weight of the high-density polyethylene resin in the present invention. Parts to 65 parts by weight and low density polyethylene resin 1
A support for image material in the present invention (Sample No. 2, No. 3, No. 4, No. 5, No. 5, which is a compound resin prepared by previously melting and mixing with 0 to 35 parts by weight). No. 6 and No. 11), the polyethylene resin composition has good moldability and does not generate gel-like foreign matter, and further has adhesiveness between the base paper and the resin layer, curl physical properties, cutting property and It can be clearly seen that it is an excellent support for image materials having good smoothness. In particular, from the overall performance of the support for image materials, the table,
The difference in the resin coating amount in the back resin layer is preferably larger than 3 g / m ² , and the HDPE content is 8 g / m ^2.
It is clearly understood that the range of 5 to 70 parts by weight is preferable.

On the other hand, it can be seen that the samples other than the invention each have problems. When the content of the high-density polyethylene resin is more than 90 parts by weight (Sample No. 1), the moldability of the polyethylene resin composition is poor, and many gel-like foreign matters are generated. When the content of the high-density polyethylene resin is less than 65 parts by weight (Sample No. 12),
This is a problem because the physical properties of curls are poor. In addition, as a method for preparing a polyethylene resin composition, simple mixing (Sample N
o. In 10), the polyethylene resin composition has poor moldability and cuttability, and many gel-like foreign substances are generated from the beginning, which is a problem. Furthermore, when the difference in the resin coating amount between the front and back resin layers is less than 3 g / m ² (Samples No. 7, No. 8 and No. 9), the cuttability and smoothness are poor, causing a problem. is there.

Example 2 Sample No. of Example 1 In place of the polyethylene resin composition for backside coating used in Example 5, the polyethylene resin shown in Table 2 was used in the composition shown in Table 3 to prepare the sample No. 1 of Example 1. Sample No. 1 of Example 1 except that it is used as a compound resin composition prepared in the same manner as in Example 5. The same procedure as 5 was performed.

[0058]

[Table 2]

The results obtained are shown in Table 3. Note that (Note 1) in the table has the same meaning as that in Table 1.

[0060]

[Table 3]

From the results shown in Table 3, the polyethylene resin in the back resin layer has a MFR of 10 g / 10 min to 40 g / 10 min and a density of 0.960 g / cm ³ or more.
0 to 65 parts by weight and MFR 0.2g / 10 minutes to 2g / 10
Min, density 0.935 g / cm ³ or less, molecular weight 500,000 or more fraction 10 wt% or more, critical shear rate 0.5 (1 /
Second) 10 parts by weight or less of low-density polyethylene resin of 3 to 3
A compound resin composition prepared by previously melting and mixing 5 parts by weight with a critical shear rate of 10
The support for image materials (Samples No. 13 to No. 23) of the present invention, which is (1 / sec) or less, has good moldability of the polyethylene resin composition and is free from gel-like foreign matter. It can be clearly seen that it is an excellent support for image materials, which does not generate, and has good adhesiveness between the base paper and the resin layer, curl properties, cuttability and smoothness.

Particularly, as the low-density polyethylene resin used in the practice of the present invention, those having an MFR of less than 1 g / 10 minutes are preferable from the viewpoint of preventing the generation of gel-like foreign matter (Sample No. 14 and No. 14). .20 and sample No. 21). Further, as the high-density polyethylene resin used in the practice of the present invention, those having a density of 0.962 g / cm ³ or more are preferable from the viewpoint of curl physical properties (Sample No. 14 and No. 18 and Sample No. 19). In comparison with the molding processability, the effect of preventing gel foreign matter, and the adhesiveness between the base paper and the resin layer, the MFR is 10 g /
It is preferably in the range of 10 minutes to 30 g / 10 minutes (Sample No. 1)
4, No. 18 and No. 22 and No. 23). Further, the compound resin composition used in the practice of the present invention has a critical shear rate of 8 (1
/ Sec) is preferable (Samples No. 13 to No. 13).
20 and No. 22 and sample No. 21 and No. 23).

On the other hand, it can be seen that the samples other than the present invention have problems. Low density polyethylene resin M
If FR is greater than 2g / 10 minutes (Sample No. 26),
This is a problem because the moldability and the degree of generation of gel-like foreign matter are poor, and the fraction of the low-density polyethylene resin having a molecular weight of 500,000 or more is lower than 10% by weight (Sample No. 26-
No. 28) has a problem in that the moldability is poor, and the gel-like foreign matter tends to increase. If the MFR of the high-density polyethylene resin is larger than 40 g / 10 minutes (Sample No. 30), the moldability, the degree of generation of gel-like foreign matter, and the adhesiveness between the base paper and the resin layer are poor. Is. The critical shear rate of the compound resin composition is 1
When it is larger than 0 (1 / second) (Sample No. 24 to No. 27)
And No. In 30), many gel-like foreign matters are generated, which is a problem.

[0064]

According to the present invention, no gel-like foreign matter is generated in the resin layer on the side opposite to the side on which the image forming layer is provided, and the adhesiveness between the resin layer and the base paper is good, and It is possible to provide an excellent support for resin-coated paper-type image material, which has good curl properties, cuttability and smoothness, can be produced at high speed, and can be stably produced.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a shear stress and a first normal stress difference and a shear rate, in which the vertical axis represents the shear stress and the first normal stress difference, and the horizontal axis represents the shear rate.

[Explanation of sign]

 a Shear stress b First normal stress difference

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical display location D21H 19/20 G03C 1/81 (72) Inventor Nobushige Ikeya 3-chome, Shiodo, Kurashiki-shi, Okayama Address Mitsubishi Kasei Co., Ltd. Mizushima Plant (72) Inventor Takuya Seri 3-10 Shiodori, Kurashiki City, Okayama Prefecture Mitsubishi Kasei Co., Ltd. Mizushima Plant (72) Inventor Kohei Nitta 3-10 Shiodori, Kurashiki City, Okayama Prefecture Address Mitsubishi Kasei Co., Ltd. Mizushima Plant

Claims (4)

[Claims] 1. A support for an image material in which both sides of a paper substrate are covered with a resin layer made of a resin composition containing a polyethylene resin as a main component, and the resin in the resin layer on the side where an image forming layer is provided is coated. The difference between the coating amount and the coating amount of the resin in the resin layer on the side opposite to the side on which the image forming layer is provided is 3 g / m ² or more, and polyethylene in the resin layer on the side opposite to the side on which the image forming layer is provided. The system resin has a melt flow rate defined by JIS K 6760 of 10 g / 10 min to 40 g / 10 min and a density of 0.
90 parts by weight to 65 parts by weight of high-density polyethylene resin of 960 g / cm ³ or more, melt flow rate specified by JIS K 6760 of 0.2 g / 10 minutes to 2 g / 10 minutes, and density of 0.935 g / cm ³ Below, the fraction with a molecular weight of 500,000 or more is 10
It is a compound resin prepared by previously melting and mixing 10 parts by weight to 35 parts by weight of a low density polyethylene resin or a medium density polyethylene resin having a critical shear rate of 0.5 (1 / sec) or less by weight or more. A support for image material, wherein the compound resin has a critical shear rate of 10 (1 / sec) or less. The critical shear rate of the resin referred to here is 2 using a cone-plate type rotary viscometer.
The shear rate (unit: 1 / sec) at the point where the difference between the shear stress measured at 40 ° C. and the first normal stress is equal. 2. A support for an image material according to claim 1, wherein the low-density polyethylene resin or the medium-density polyethylene resin has a melt flow rate specified by JIS K 6760 of 0.2 g / 10 minutes or more and less than 1 g / 10 minutes. body. 3. The support for image materials according to claim 1, wherein the resin layer on the side where the image forming layer is provided contains a titanium dioxide pigment. 4. The support for image materials according to claim 1, 2 or 3, wherein the image forming layer is a silver halide photographic constituent layer.