JPH10329293A - Manufacture of support for polyester photographic paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photographic image forming layer and a highly adhesive coating layer by applying a coating liquid containing a specific dry polymerization percentage ratio of aqueous polyester and aqueous epoxy group-containing compounds, at least, on one of the faces of white polyester film with specific concealing properties and drying the coating. SOLUTION: A polyester film has to be white and this white polyester film is obtained by adding and dispersing a non-compatible organic polymer or an inorganic or organic particle into polyester before forming a coating. A coating layer to be formed on the polyester film comprises aqueous polyester (A) and an aqueous epoxy group-containing compound (B), and the dry weight rate is in the relationship of 30/70<=A/B<=90/10. The aqueous polyester (A) is a water-soluble or a moisture dispersible polyester resin coating agent using water as a principal coating medium. The aqueous epoxy group-containing compound is preferably glycidyl ethers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyester-based photographic printing paper support, and more particularly, to a method for producing a white support having an undercoat layer having excellent adhesion to a photographic image forming layer provided on the support. The present invention relates to a method for producing a polyester film. More specifically, the present invention is a method for producing a white polyester film provided with a coating layer having excellent adhesion to a photographic image forming layer mainly comprising gelatin as a main binder.

[0002]

2. Description of the Related Art As a support on which a photographic image forming layer is provided as photographic printing paper, paper has been used for many years. For photographic printing paper, paper is a material having excellent points in appearance, feel, mechanical properties, price, and the like. On the other hand,
Paper has a characteristic of easily absorbing and impregnating water, and it is used after being subjected to various water-resistant treatments.However, it is difficult to completely prevent absorption from the edges, and it remains after photographic processing. However, there remains a problem that an image becomes yellowish with time due to the developer component.

[0003] In addition to water resistance, a white plastic film called synthetic paper is used in order to obtain mechanical properties, luxuriousness, and image quality not available in paper. One of such synthetic papers is a white polyester film. Polyester films are widely used because of their well-balanced properties, and are used as materials in photographic paper applications.

On the other hand, polyester films represented by polyethylene terephthalate and polyethylene-2,6-naphthalate have poor surface activity, and are provided by overcoating a photographic emulsion mainly containing gelatin as a main component of a binder. It also has the disadvantage that the adhesion to the layer is very poor. The adhesiveness with the photographic image forming layer as a support for photographic printing paper must be exhibited not only when the finished photograph is dry but also in a wet state during photographic processing represented by development processing. . For this reason, when a polyester film is used as a support, there is often employed a technique in which a certain kind of polymer layer is provided on the film before the photographic image forming layer is provided to form an easily adhesive layer.

Specifically, it is known to provide a layer such as a polyester copolymer, a vinylidene chloride copolymer, a mixture of gelatin and a hydrophilic vinyl or acrylic copolymer, or a carboxy-modified polyethylene. Further, the polyester film may be subjected to a pretreatment such as a corona discharge treatment before providing the polymer layer.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a polyester-based photographic printing paper support having excellent adhesion to a photographic image forming layer. It is in. Specifically, an object of the present invention is to provide a white polyester film provided with a photographic image forming layer and an undercoat layer exhibiting excellent adhesiveness when dry and wet.

[0007]

That is, the gist of the present invention is to provide a coating solution containing an aqueous polyester and an aqueous epoxy group-containing compound in a dry weight ratio of 30/70 to 90/10, for a white polyester film. A method for producing a support for a polyester-based photographic printing paper, characterized in that the support is coated on at least one side and dried.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
As the polyester of the polyester film referred to in the present invention, typically, for example, polyethylene terephthalate (PET) in which at least 80 mol% of the structural units are ethylene terephthalate, and at least 80 mol% of the structural units are ethylene-2,6-naphthalate Polyethylene-2,6-
Naphthalate (PEN), poly-1,4-cyclohexane dimethylene terephthalate in which 80% by mole or more of the structural unit is 1,4-cyclohexane dimethylene terephthalate, and the like, and polyethylene isophthalate, polybutylene terephthalate, and the like are also used. Can be.

[0009] The copolymerization components other than the above-mentioned predominant constituents include, for example, diol components such as diethylene glycol, propylene glycol, neopentyl glycol, polyethylene glycol and polytetramethylene glycol;
Isophthalic acid, 2,7-naphthalenedicarboxylic acid, 5-
Ester-forming derivatives such as sodium sulfoisophthalic acid, adipic acid, azelaic acid, sebacic acid and oxymonocarboxylic acid can be used. In addition, as a polyester, in addition to a homopolymer or a copolymer,
Small proportion blends with other resins can also be used.

The intrinsic viscosity ([η]) of such a polyester is usually at least 0.45, preferably at least 0.50.
1.0, more preferably in the range of 0.52 to 0.90. If the intrinsic viscosity is less than 0.45, there may be a problem that productivity during film production is reduced and mechanical strength of the film is reduced. On the other hand, it is preferable that the intrinsic viscosity does not exceed 1.0 from the viewpoint of melt extrusion stability of the polymer.

As the polyester film of the present invention, a biaxially stretched polyester film is particularly preferably used in view of the required characteristics of a photographic printing paper support. As a method for producing such a polyester film, a generally known method can be employed, and the stretching method is either simultaneous biaxial stretching or sequential biaxial stretching, and in particular, sequential biaxial stretching is often performed.

A more specific method for producing such a polyester film will be described. The polyester raw material is supplied to an extruder, melt-extruded at a temperature equal to or higher than the melting point of the polyester, and extruded as a molten sheet from a slit die. Next, the molten sheet is quenched and solidified on a rotary cooling drum so as to have a temperature equal to or lower than the glass transition point to obtain a substantially amorphous unstretched sheet. In this case, in order to improve the flatness of the sheet, it is necessary to increase the adhesion between the sheet and the rotary cooling drum, and in the present invention, the electrostatic application adhesion method and / or the liquid application adhesion method are preferably employed.

The unstretched sheet obtained in this way is
Axial stretching is performed, and here, longitudinal and horizontal sequential biaxial stretching will be described as an example. Generally, an unstretched sheet is stretched (longitudinal stretching) in the longitudinal direction of the sheet by a group of rolls having a difference in peripheral speed. First, the sheet is preheated and maintained at a temperature equal to or higher than the glass transition point and equal to or lower than the melting point. In the case of PET, the temperature is preferably in the range of 70 to 150 ° C, and in the case of PEN, the temperature is preferably in the range of 115 to 170 ° C. Thereafter, the film is stretched to a total magnification of 2 to 10 times using the difference in peripheral speed of the roll. At this time, the stretching can be performed in one stage or two or more stages. Next, the film is stretched (transversely stretched) in the transverse direction, that is, in the direction perpendicular to the longitudinal direction. That is, once the obtained uniaxially oriented film is cooled to or below the glass transition point, or without cooling, the glass transition point or more, the temperature below the melting point, 80-150 ℃ if PET,
If it is PEN, the range of 120 ° C to 180 ° C is preferable,
The film is stretched 2 to 10 times while gripping the end of the film with a normal clip.

Here, an example in the order of longitudinal stretching and transverse stretching is shown, but the order may be reversed, and each stretching may be performed by dividing it into several times. Also split,
A part of them may be implemented alternately. For example, a method of manufacturing a high-strength film by a re-stretching method corresponds to this.
The biaxially oriented film thus obtained is usually 30
Heat treatment with% elongation, limited shrinkage, or constant length. The heat treatment time is usually preferably in the range of 1 second to 5 minutes. At this time, a method of performing a relaxation treatment within 10%, preferably within 5% within or after the heat treatment step can be also adopted particularly in order to keep the heat shrinkage in the longitudinal direction within a suitable range. The heat treatment temperature depends on the stretching conditions, but is still higher than the glass transition point and lower than the melting point, for example, 170 ° C. for PET.
To 250 ° C., and preferably 170 to 270 ° C. for PEN.

If the heat treatment is long, for example, the treatment time is long or the treatment temperature is high, the crystallization of the polyester proceeds too much, and when the coating layer is formed by in-line coating described later, the thermal decomposition of the resin forming the coating layer may occur. May occur. If the heat treatment is too small, the shrinkage of the film will increase. In any case, conditions are selected in which the properties of the finally obtained film meet the requirements as a support for photographic printing paper.

The thickness of the resulting photographic paper support is appropriately selected depending on the use of the photographic paper, but is preferably in the range of 15 to 350 μm. When the thickness is less than 15 μm, the rigidity as a support tends to be insufficient, and when the thickness is more than 350 μm, the weight of the material as photographic paper tends to increase and handling tends to be poor, which is disadvantageous in cost.

Further, such a film can be bonded to a base material such as paper and used with a desired thickness. By the way, an oriented and crystallized biaxially stretched polyester film that does not contain particles, fine bubbles, and the like generally has good transparency. However, in order to obtain a clear image as a photographic printing paper support, in the present invention, the film must be white.

Such a white polyester film is
It can be obtained by mixing and dispersing organic or inorganic or organic particles incompatible with the polyester before film formation. In addition, the inclusion of particles allows the film to form appropriate protrusions and impart slipperiness,
It also contributes to preventing scratches in the film and improving productivity.

Examples of such particles include calcium carbonate, calcium phosphate, silica, kaolin, talc,
Titanium dioxide, alumina, barium sulfate, calcium fluoride, lithium fluoride, zeolite, molybdenum sulfide,
Examples include crosslinked organic polymer particles, calcium oxalate, and precipitated particles formed during the polymerization of polyester.

A plurality of these particles can be used, and among them, it is preferable to use at least one of so-called white pigments in view of the whiteness of the film and the concealing property. Among the white pigments, calcium carbonate, barium sulfate, and titanium dioxide are particularly preferred, and one of the particles used is preferably one of them.

In the case of titanium dioxide, the crystal form may be either anatase or rutile, but is more preferably anatase titanium dioxide from the viewpoint of whiteness and weather resistance. Further, titanium dioxide particles whose surfaces are treated with an oxide and / or an organic compound such as aluminum, silicon, and zinc for the purpose of improving the dispersibility in polyester and the weather resistance may be used.

Usually, the average particle size of these particles is preferably 0.005 to 5.0 μm, more preferably 0.01 to 5.0 μm.
It is in the range of 3.0 μm. If the average particle size exceeds 5.0 μm, the film surface may be excessively roughened, and the quality of the photographic image may be degraded, or the particles may easily fall off the surface. Average particle size 0.005μ
If it is less than m, the formation of projections by these particles is insufficient, so that the surface of the film is liable to be scratched or the handleability of the film tends to be reduced.

Further, the content of particles is
0.3 to 30% by weight, preferably 0.5 to 20% by weight,
More preferably, the content is 1.0 to 20.0% by weight. 0.
When the content is less than 3% by weight, the whiteness of the film surface is insufficient, and the quality of the photographic image, particularly, the contrast and the sharpness tend to be insufficient. On the other hand, if the particle content exceeds 30.0% by weight, there is a possibility that the particles may easily fall off, or the particles may aggregate to form coarse projections.

In the production of polyester containing particles,
The particles may be added during the polyester synthesis reaction or may be added directly to the polyester. When it is added during the synthesis reaction, a method in which the particles are added as a slurry in which the particles are dispersed in ethylene glycol or the like at an arbitrary stage of polyester synthesis is preferable. On the other hand, when it is directly added to the polyester, it is used as dried particles or water or a compound having a boiling point of 2%.
As a slurry dispersed in an organic solvent at
A method of adding and mixing with polyester using a shaft kneading extruder is preferred. The particles to be added may be subjected to a process such as crushing, dispersion, classification, and filtration, if necessary, beforehand.

As a method of adjusting the content of particles, a master material containing particles at a high concentration is prepared in the above-described manner, and is diluted with a material substantially containing no particles at the time of film formation. A method of adjusting the particle content is effective. The film produced according to the present invention is required to have high whiteness in terms of the quality of a photographic image. Therefore, it is preferable to contain a fluorescent whitening agent in addition to the above-mentioned particles, particularly a white pigment. As the fluorescent whitening agent, a wavelength of 400 to 700
Any type may be used as long as it has a fluorescence peak at nm.
Commercially available products such as "D" (manufactured by Ciba-Geigy), "OB-1" (manufactured by Eastman), and "Mica White" (Nippon Kayaku-Mitsubishi Chemical). The content of the optical brightener in the polyester film is usually 50 to 5000 ppm, preferably 100 to 3000 ppm. If the content of the fluorescent whitening agent is less than 50 ppm, the whiteness tends to be insufficient. If the content of the fluorescent whitening agent exceeds 5000 ppm, heat deterioration may occur in the mixing step of an extruder or the like when blending the whitening agent into the polyester.

In addition to the whitening of the film, fine bubbles can be contained in the film for the purpose of lowering the density of the film and imparting cushioning properties. The method for producing the polyester film containing microbubbles is not particularly limited, but from the viewpoint of cost and productivity, JP-A-63-168441 and JP-A-63-19393.
It is preferable to carry out the method described in Japanese Patent Publication No. 8 or the like or a method analogous thereto.

That is, a method in which a polymer incompatible with the polyester is blended with the polyester, extruded into a sheet, and then the obtained sheet is stretched in at least one direction to form a film. Examples of polymers that are incompatible with polyester include polyethylene, polypropylene, polymethylpentene, polyolefins such as polymethylbutene, polystyrene, polycarbonate, polyphenylene sulfide, and liquid crystal polyester. From the viewpoint, polypropylene is preferred.

The amount of the immiscible polymer is usually 5 to 40% by weight, preferably 5 to 30% by weight, based on the polymer constituting the film. If the content is less than 5% by weight, the content of bubbles tends to be small, and there is a possibility that the weight and the cushioning property may be insufficiently provided.
On the other hand, when the content is more than 40% by weight, the film tends to be frequently broken at the time of stretching, resulting in poor productivity.

In the method of blending the incompatible polymer with the polyester as described above, it is necessary to further stretch at least uniaxially. This is because not only the film is imparted with mechanical strength as described above, but also it is possible to contain sufficient closed cells only after the stretching step. This stretching method itself does not require a special operation, and is performed within the range of conditions for producing a normal polyester film.

When polypropylene is used as the incompatible polymer, it is preferable that at least 95 mol% or more, preferably 98 mol% or more, is a crystalline polypropylene homopolymer having propylene units. When the polypropylene is amorphous, it is not preferable because when the amorphous polyester sheet is formed, the polypropylene bleeds out on the sheet surface and contaminates the surface of the cooling drum, the stretching roll, and the like. On the other hand, if the propylene units are copolymerized in an amount exceeding 5 mol%, the formation of closed cells becomes insufficient, which is not preferable.

The melt flow index (MFI) of such polypropylene is usually in the range of 0.5 to 30 g / 10 minutes. If the MFI is less than 0.5 g / 10 min, the generated bubbles become large and breakage occurs during stretching. On the other hand, if the MFI exceeds 30 g / 10 min, the clip in the tenter may be detached or the density of the tenter may increase. In some cases, the uniformity of the target is poor, the density control becomes difficult, and the productivity may be deteriorated.

In the case of using the method of forming fine bubbles by blending an incompatible polymer as described above, in order to control the size of the bubbles and bring the density and cushioning property of the film into the desired ranges, It is preferable to include a surfactant therein. Examples of the surfactant include an anionic surfactant, a cationic surfactant, an amphoteric surfactant, and a nonionic surfactant. Among them, a nonionic surfactant, particularly a silicone surfactant is used. preferable. Examples of the silicone surfactant include an organopolysiloxane-polyoxyalkylene copolymer and an alkenylsiloxane having a polyoxyalkylene side chain. The content of the surfactant is preferably 0.001 to 1.0% by weight, more preferably 0.01 to 0.5% by weight based on the raw material. When the content of the surfactant exceeds 1.0% by weight, the effect is no longer improved, and troubles in the extruder and deterioration of the polymer may be caused.

Although it is possible to obtain a certain degree of whiteness and hiding degree of the film only by including such fine bubbles, it is difficult to obtain sufficient image clarity. Accordingly, the above-mentioned particles, particularly a white pigment and a fluorescent whitening agent can be contained, which is preferable. In addition, if necessary, as an additive other than the above, an antistatic agent, a stabilizer, a lubricant, a cross-linking agent, an anti-blocking agent, an anti-oxidant, and a coloring agent within a range that does not impair the performance as a support for photographic printing paper. Agents (dyes and pigments), light-blocking agents, ultraviolet absorbers, and the like.

In general, a white polyester film as a support for photographic printing paper is preferable because the higher the whiteness and hiding degree, the smaller the surface roughness on the image forming layer side, the better the sharpness of the resulting image. . These characteristics allow the white pigment, fluorescent whitening agent, fine bubbles, and the like to be designed in accordance with the level required for photographic paper. A multilayer structure may be used as long as the properties finally obtained satisfy the requirements as a support for photographic printing paper. For example, it may be a co-extruded laminated film. Even with such a multilayer structure, whiteness, hiding degree, and surface roughness can be designed to any values.

The whiteness of the photographic printing paper support film produced according to the present invention is less than 2.0, preferably less than 1.0, and more preferably less than 0.5 in terms of b value which is an indicator of yellowishness. It is. If the b value is 2.0 or more, yellowness becomes strong and whiteness becomes insufficient, which is not preferable. The hiding degree (OD), which is an index indicating the hiding properties of the film, is 0.1.
It is 3 or more, preferably 0.4 or more. If the OD is less than 0.3, the prevention of light transmission becomes insufficient, and the photographic image becomes unclear, which is not preferable.

In addition, fine bubbles are formed by white polyester fill.
When it is contained in a medium, its apparent density (ρ) is usually 0.1.
6 to 1.2 g / cm^Three, Preferably 0.7 to 1.1 g /
cm ^ThreeIt is. ρ is 0.6 g / cm^ThreeIf less than
In this case, rupture frequently occurs, and the productivity tends to deteriorate.
ρ is 1.2 g / cm^ThreeIf it exceeds
Cushioning characteristic, a characteristic of steal, tends to be poor
There is a direction.

Next, the coating layer provided on the white polyester film in the present invention will be described. The coating layer is formed by applying a coating solution on the film and then drying the coating solution. The coating may be performed after the production of the white polyester film, or may be performed in a white polyester film production process. The latter method is a so-called in-line coating method. In order to perform in-line coating, the coating liquid desirably satisfies several requirements, and the coating layer provided in the present invention is preferably provided by in-line coating. Such requirements include, for example, that there is no extreme cracking of the coating layer due to stretching after coating, that the coating properties are good, that the performance is sufficiently exhibited even in a thin film, that the coating liquid is aqueous, and the like. It is to satisfy.

The in-line coating referred to here is a method in which various materials such as polyester are melted and extruded, and then applied at an arbitrary place from biaxial stretching to heat setting and winding up. A substantially amorphous unstretched sheet formed by quenching, or a uniaxially stretched film after being stretched in the longitudinal direction (also called longitudinal direction) (before being stretched in the transverse direction), biaxial before heat fixing It is applied to any of the stretched films. Among these, the method of applying to a uniaxially stretched polyester film in the longitudinal direction and further stretching the film in a dry or undried state in the transverse direction is excellent. The reason is that film formation and coating and drying can be performed at the same time, so there is an advantage in manufacturing cost, it is possible to apply a thin film because it is stretched after coating, and high temperature where heat treatment performed after coating is not achieved by other methods And
For this reason, the coating film and the polyester film are strongly adhered to each other.

In order to perform in-line coating, the coating solution is preferably an aqueous solution from the viewpoints of safety and working environment. The coating solution used in the present invention is a coating solution containing an aqueous polyester and an aqueous epoxy group-containing compound. Liquid is required. However, in order to improve the stability, dispersibility, coatability and the like of the coating solution, a small amount of an organic solvent can be used in combination as needed. The same applies to the aqueous polyester and the aqueous epoxy group-containing compound described below. Further, depending on the organic solvent contained in these raw materials, it is possible that the organic solvent is eventually contained in the coating composition.

As the above-mentioned organic solvent, a relatively hydrophilic one is preferably used. Specifically, aliphatic, alicyclic alcohols, glycols, esters, ethers,
Amide compounds and the like, more specifically, methanol, ethanol, isopropanol, n-butanol and the like as alcohols, ethylene glycol, propylene glycol, diethylene glycol and the like as glycols, ethyl acetate, amyl acetate and the like as esters, ethers and the like. As methyl cellosolve, ethyl cellosolve, n-butyl cellosolve, t-butyl cellosolve,
Examples of ketones such as dioxane and tetrahydrofuran, such as acetone and methyl ethyl ketone, acetonitrile, N-methylpyrrolidone, and N, N-dimethylformamide. These organic solvents may be used alone or in combination of two or more as needed.

When the main component of the coating liquid and each coating agent is water, the compound may be forcibly dispersed with a surfactant or the like, but may be a self-dispersing coating agent. This is preferable from the viewpoint of dispersion stability of the coating solution. The self-dispersion type coating agent is a coating agent in which various hydrophilic groups are introduced into a compound by a chemical bond. For example, the nonionic group includes a hydroxyl group, a polyether, the anionic group includes a sulfonic acid, a carboxylic acid, a phosphoric acid and salts thereof, and the cationic group includes a hydrophilic component such as an onium salt such as a quaternary ammonium salt. However, these chemical species can be introduced by copolymerization or grafting to form a self-dispersing coating agent.

As a method of applying a coating solution to a polyester film, for example, Yuji Harazaki, Maki Shoten, 1979
A reverse roll coater, a gravure coater, a rod coater, an air doctor coater, or a coating device other than these, as shown in “Coating System”, published every year, can be used. The thickness of the final coating layer is usually 0.001 to 10 μm, preferably 0.010 to 5 μm, more preferably 0.015 to 2 μm.
μm. If the coating layer is thin, the adhesiveness to the photographic photosensitive layer expected of the coating layer may not be sufficiently exhibited. On the other hand, if the coating layer is thick, the coating layer acts like a pressure-sensitive adhesive, and the films wound up on a roll adhere to each other, resulting in so-called blocking. Further, it is not preferable to increase the thickness of the coating layer unnecessarily from the viewpoint of manufacturing cost and productivity.

The term "aqueous polyester" as used in the present invention means a water-soluble or water-dispersible polyester resin coating agent using water as a main coating medium. Examples of the components constituting such a polyester resin include the following polyvalent carboxylic acids and polyvalent hydroxy compounds. That is, as the polyvalent carboxylic acid, terephthalic acid, isophthalic acid, orthophthalic acid, phthalic acid, 4,4′-diphenyldicarboxylic acid, 2,5-naphthalenedicarboxylic acid,
2,6-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 2-potassium sulfoterephthalic acid,
5-sodium sulfoisophthalic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, glutaric acid, succinic acid, trimellitic acid, trimesic acid, trimellitic anhydride, phthalic anhydride, p-hydroxybenzoic acid, tri Monopotassium melitate, pyromellitic acid and their ester-forming derivatives can be used. Examples of the polyvalent hydroxy compound include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3 -Propanediol, 1,4-
Butanediol, 1,6-hexanediol, 2-methyl-1,5-pentanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, p-xylylene glycol, bisphenol A-ethylene glycol adduct, diethylene glycol, triethylene glycol Ethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polytetramethylene oxide glycol, dimethylolpropionic acid,
Glycerin, trimethylolpropane, sodium dimethylolethylsulfonate, potassium dimethylolpropionate and the like can be used.

One or more of these compounds are appropriately selected, and a polyester resin is synthesized by a conventional polycondensation reaction. Of these, terephthalic acid, isophthalic acid, 2,6- Naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid and ester-forming derivatives thereof, and polyhydric hydroxy compounds include ethylene glycol, diethylene glycol, triethylene glycol, neopentyl glycol, and 1,4-cyclohexanedimethanol. . Further, during the polyester polycondensation reaction, an etherification reaction between the hydroxy compounds may be performed.

As described above, such a polyester resin is preferably self-dispersed, rather than being forcibly dispersed with a surfactant or the like. Therefore, it is desirable to introduce the following hydrophilic functional groups or hydrophilic sites into the resin. Examples of such a hydrophilic functional group include acids or bases that ionize and ionize in water, and salts thereof, and a hydroxyl group. Examples of the hydrophilic portion include ethers, particularly polyethers, esters, and amides. Is mentioned. Among these, in the present invention, it is preferable to introduce an anionic group which is an acid or a salt thereof from the viewpoint of other properties such as dispersibility of a coating agent, stability, adhesion of a coating layer, and the like. From the point of view, the problem can be relatively reduced.

The polyester resin having an anionic group can be obtained by bonding a compound having an anionic group to a polyester by copolymerization, grafting, or the like. Selected from lithium salts, sodium salts, potassium salts, ammonium salts and the like. In particular, it is preferable to copolymerize a monomer having such an anionic group or generating an anionic group after polymerization in a polyester resin.

Such monomers are the same as the above-mentioned polyester-constituting compounds, but in particular, 5-sulfoisophthalic acid and its salts, trimellitic acid, pyromellitic acid and their acid anhydrides, and polyhydric acids thereof Suitable compounds include ester-forming derivatives of carboxylic acids. After the polymerization, if necessary, neutralization or pH adjustment may be performed with the above-mentioned alkali metal or amine compound.

The amount of the copolymerizable monomer for introducing an anionic group into the polyester resin is 0.5 to 25 mol%, preferably 1 to 20 mol%, based on the total polycarboxylic acid or the total polyhydroxy compound. In particular, it is desirable to be in the range of 2 to 15 mol%. If the amount of the anionic group-introduced comonomer is less than 0.5 mol%, the water solubility or water dispersibility of the polyester resin tends to deteriorate,
If it exceeds mol%, the water resistance of the coating layer may be poor, or the films may adhere to each other due to moisture absorption. Also,
The polymerizability of the polyester-based resin may also be deteriorated.

Further, two or more of these polyester resins may be used in the coating solution. The aqueous epoxy group-containing compound in the present invention is a coating agent for a compound containing an epoxy group that is water-soluble or water-dispersible using water as a main coating medium, and the compound has at least one epoxy group in the molecule. , Preferably two or more.

Examples of the epoxy group-containing compound include glycidyl ethers of glycols, polyethers and polyols, glycidyl esters of carboxylic acids, and glycidyl-substituted amines, and preferably glycidyl ethers. is there. These glycidyl compounds can be easily obtained by reaction with epichlorohydrin, but the synthesis method is not limited thereto. Specific examples: sorbitol polyglycidyl ether, sorbitan polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, triglycidyl tris (2-hydroxyethyl) isocyanurate, glycerol polyglycidyl ether , Trimethylolpropane polyglycidyl ether, resorcinol diglycidyl ether, neopentyl glycol diglycidyl ether,
1,6-hexanediol diglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, polytetramethylene glycol diglycidyl ether, adipic acid diglycidyl ether,
Orthophthalic acid diglycidyl ether, hydroquinone diglycidyl ether, bisphenol S diglycidyl ether, terephthalic acid glycidyl ester, dibromoneopentyl glycol diglycidyl ether, and the like, but are not limited thereto. Epoxy emulsions are sold by various companies. For example, “Denacol EM-12” manufactured by Nagase Kasei Kogyo Co., Ltd.
5) "Denacol EX-1101""DenacolE"
X-1102 "," Denacol EX-1103 "and the like, but are not limited thereto.

Two or more of these epoxy group-containing compounds may be used in the coating solution, and it is natural that some or more kinds of the compounds are usually mixed during the synthesis of the compound. In the present invention, it is an important requirement to provide a coating layer on a polyester film using a coating solution containing the aqueous polyester and the aqueous epoxy group-containing compound in a certain ratio. The expression must be satisfied.

That is, when the dry weight ratio of the aqueous polyester and the aqueous epoxy group-containing compound is

[0053]

It is essential that 30/70 ≦ aqueous polyester / aqueous epoxy group-containing compound ≦ 90/10. When the ratio of the aqueous polyester / aqueous epoxy group-containing compound is less than 30/70,
The provided coating layer is not excellent in adhesion to the polyester film as the support, and the water resistance of the coating layer is poor. Further, the resulting film has poor blocking properties.
On the other hand, when the ratio of the aqueous polyester / aqueous epoxy group-containing compound is larger than 90/10, the adhesiveness between the obtained coating layer and the overcoated photographic photosensitive layer is unfavorably deteriorated.

The present invention is characterized by using a coating solution containing a plurality of specific compounds in a specific ratio as described above. However, as long as the gist of the present invention is not impaired, other compounds may be used as an aqueous polyester or an aqueous epoxy resin. It may be blended within 40% by dry weight based on the total amount of the group-containing compounds. For example, inorganic or organic fine particles, wax, antistatic agent, surfactant, defoamer, coating improver, thickener, antioxidant, ultraviolet absorber, foaming for the purpose of improving blocking property and slipperiness Agents, dyes, pigments and the like.

The film before coating may be subjected to a chemical treatment or a discharge treatment in order to improve the coating properties and adhesion of the coating solution to the film. Further, for the purpose of improving the coatability, adhesiveness and the like between the polyester film of the present invention and the photographic photosensitive layer, a discharge treatment may be performed after the formation of the coating layer. Various photographic printing papers can be prepared by providing at least one photographic image forming layer on the photographic printing paper support of the present invention. For example, a silver halide photographic emulsion layer can be provided.

Such a photographic emulsion preferably uses gelatin as a main binder. As the silver halide emulsion, various conventional silver halide emulsions can be arbitrarily used. The emulsion can be chemically sensitized by a conventional method,
A desired wavelength region can be optically sensitized by using a sensitizing dye. Further, an antifoggant, a stabilizer, a hardener and the like can be added to the silver halide emulsion. Hardening agents include aldehyde, aziridine, isoxazole, epoxy, vinyl sulfone, acryloyl, carbodiimide, triazine, polymer, and other maleimide, acetylene, and methanesulfonic acid ester Hardening agents can be used alone or in combination of two or more. Also, plasticizers, dispersions (latex) of water-insoluble or hardly soluble synthetic polymers, couplers, coating aids, antistatic agents, formalin scavengers,
A fluorescent whitening agent, a matting agent, a lubricant, an image stabilizer, a surfactant, a color fogging inhibitor, a development accelerator, a development retarder and a bleaching accelerator can be contained. The photographic light-sensitive material can be provided with an auxiliary layer such as a protective layer, a filter layer, a back coating layer, an antihalation layer, an anti-irradiation layer, and an intermediate layer, in addition to the silver halide emulsion layer. Such a photographic photosensitive layer and other layers are appropriately selected depending on the intended use, and are not limited to the examples shown here.

[0057]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention. The evaluation method in the present invention is as follows. (1) Dry weight of coating liquid (coating agent) It was determined according to JIS K 5407-4. (2) Intrinsic viscosity of polyester ([η]) (dl /
g) 1 g of polyester is phenol / tetrachloroethane =
Dissolved in 100 ml of a 50/50 (weight ratio) mixed solvent,
It was measured at 30 ° C. (3) Opacity (OD) The transmitted light density under the G filter was measured using a Macbeth densitometer (TD-904). (4) b value Tokyo Denshoku Co., Ltd. color analyzer TC1800MK
Using type II, b according to the method of JISZ-8722
The value was measured. (5) Apparent density of film (ρ) (g / cm ³ ) A 10 cm × 10 cm square sample was cut out from an arbitrary portion of the film, and its weight was measured. Next, the thickness at nine arbitrary points was measured with a micrometer, and the weight per unit volume was calculated from the average value and the weight. The number of measurements was five, and the average was taken as the film density. (6) Image forming layer (gelatin layer) adhesiveness 1 [when dry] After drying a gelatin layer containing a hardener, a latex, a matting agent, and a yellow dye for making the evaluation result easier to understand, 5
μm and after sufficient hardening, 23
C. and 50% RH. In this atmosphere, 100 square crosscuts were made at 1 mm intervals from the surface of the gelatin layer, and Nitto Denko's "Polyester Adhesive Tape No. 31" was adhered to the crosscut with care so as to prevent air bubbles from entering. A metal roll having a load of 2 kg was reciprocated 20 times on the tape. Thereafter, the substrate polyester film side was bent at 180 ° to perform a peeling test. One end of the polyester film is connected to a 1 kg weight, and this weight is
The peeling test was performed such that peeling in the 180 ° direction was started after a natural drop of 5 cm. The situation at this time was visually observed and evaluated according to the following criteria.

[0058]

[Table 1] ───────────────────────────── Evaluation status ─────────────── ◎ 良好 (Good): No peeling ○ (Normal): Peeled less than 30% △ (Somewhat bad): Peeled from 30% to less than 80% × (Poor): 80% Above peeling ───────────────────────────── The evaluation result is preferably 以上 or more, more preferably ◎. (7) Image Forming Layer (Gelatin Layer) Adhesion 2 [Wet] After a gelatin layer was provided and humidified in the same manner as in (6) above, a cross cut was similarly made. Using a felt that was immersed in water and sufficiently squeezed, it was reciprocated 30 times with a load of 500 g using Taihei Rika "rubbing tester". At this time, the remaining amount of the gelatin layer was visually observed and evaluated according to the following criteria.

[0059]

[Table 2] ───────────────────────────── Evaluation status ─────────────── ◎ (good): 100% remaining ○ (normal): 70% or more remaining Δ (slightly poor): 20% or more and less than 70% remaining × (bad): 20 % Remaining ───────────────────────────── The evaluation result is preferably ○ or more, and ◎ is more preferable. (8) Practical properties as photographic paper Only the films having good adhesion to the image forming layer in (6) and (7) were evaluated as follows. A gelatin layer containing a photoreceptor was coated on one side of the film to form a photosensitive layer, and exposed and developed to form an image. The quality of the obtained image was evaluated for the following items. Resolution Rank A: High resolution was obtained and high quality. Rank B: Slightly poor resolution, but practically acceptable. Rank C: Poor resolution due to poor resolution. Contrast Rank A: Clear contrast, A high quality image was obtained. Rank B: The contrast sharpness was slightly inferior, but practical. Rank C: The contrast was low and the image quality was inferior. Color Rank A: A good color was displayed. Rank B: Yellowness was affected. The method for producing the polyester film used in the examples is described below. (Production of Polyester A) Dimethyl terephthalate 100
Starting parts by weight and 60 parts of ethylene glycol,
0.09 parts by weight of magnesium acetate tetrahydrate was placed in a reactor as a catalyst, the reaction starting temperature was set at 150 ° C., and the reaction temperature was gradually increased with the removal of methanol, and the temperature was increased to 230 ° C. after 3 hours. After 4 hours, the transesterification reaction was substantially completed.

To this reaction mixture, 0.04 parts of ethyl acid phosphate and 0.04 parts of antimony trioxide were added, and a polycondensation reaction was carried out for 4 hours and 30 minutes. That is, the temperature was gradually raised from 230 ° C. to 280 ° C. on the other hand,
The pressure gradually decreases from normal pressure, and finally 0.3mmHg
And After 4 hours and 30 minutes from the start of the reaction, the reaction was stopped, and the polymer was discharged under nitrogen pressure. The intrinsic viscosity of the obtained polyester was 0.65. Next, the obtained polymer was treated at 225 ° C. under 0.3 mmHg under the conditions of 1 mm.
The old layer polymerization was performed for 0 hours. The intrinsic viscosity of the obtained polyester was 0.81. (Production of Polyesters B to D) Polyester A was dried, and polyesters B to D were obtained using a vented twin-screw extruder according to the formulation shown in Table 1 below.

[0061]

[Table 3] (1-1. Production of White Polyester Film: Polyester Film 1) 35 parts by weight of polyester B, 10 parts by weight of polyester C, 5 parts by weight of polyester D, and 50 parts by weight of polyester A were uniformly blended, and
After drying at 80 ° C. for 4 hours, the sheet was extruded into a sheet shape from an extruder set at 285 ° C., and rapidly cooled and solidified by a rotating cooling drum set at a surface temperature of 30 ° C. using an electrostatic application cooling method. Thus, an amorphous sheet was obtained. The obtained amorphous sheet is stretched 3.0 times in the longitudinal direction at 83 ° C., then stretched 3.8 times in the transverse direction, and heat-treated at 245 ° C. for 6 seconds to have a thickness of 188 μm and an opacity (OD). 1.
6. A biaxially stretched white polyester film having a b value of -0.6 was obtained. (1-2. Production of White Polyester Film: Polyester Films 2 and 3) Biaxial stretching was performed in the same manner as polyester film 1 except that the amount of polyester was changed as shown in Table 2 in the production of polyester film 1. A white polyester film was obtained. Table 3 below shows the film properties of the polyester films 1 to 3.

[0062]

[Table 4]

[0063]

[Table 5] (2. Production of white polyester film containing fine bubbles:
Polyester film 2) Polyester B 12.5
Parts by weight, 5 parts by weight of polyester D, polyester A
72.5 parts by weight were blended and dried at 180 ° C. for 4 hours.
Thereafter, 10 parts by weight of a crystalline polypropylene homopolymer chip having a melt flow index of 5.5 and 0.2 part by weight of a silicone-based surfactant (trade name: BH193, manufactured by Toray Silicone Co., Ltd.) were blended and uniformly blended. Thereafter, the sheet is extruded in a sheet shape from an extruder set at 290 ° C., and rapidly cooled and solidified by a rotating cooling drum set at a surface temperature of 40 ° C. using an electrostatic application cooling method, to a thickness of 247 °
A μm substantially amorphous sheet was obtained. The obtained amorphous sheet is stretched 2.9 times in the longitudinal direction at 83 ° C., then stretched 3.2 times in the transverse direction, and heat-treated at 245 ° C. for 6 seconds to have a thickness of 38 μm and a degree of concealment (OD). A white polyester film 7 containing biaxially stretched microbubbles having a 0.5, b value of -4.5, and an apparent density (ρ) of 1.0 g / cm ³ was obtained.

A coating method for providing a coating layer on a polyester film will be described below. (Coating method) During the above-mentioned white polyester film manufacturing process, after the longitudinal stretching and before the transverse stretching, the concentration of the coating solution is adjusted by using a bar coater so that the coating solution in the table described below has a thickness suitable for each example. Coating was performed by adjusting the coating thickness. The coating thickness in the table is the thickness after drying and horizontal stretching, that is, the thickness of the coating layer on the completed film.

Next, the contents of the coating agent used in the examples will be described. (Aqueous polyester) Aqueous polyesters A1 to A5 were used. The resin was copolymerized by a conventional method and dispersed in water.
The composition is shown in the following table. The unit is mol%.

[0066]

[Table 6] {A1 A2 A3 A4 A5} ─────────────────────────────── <Polyvalent carboxylic acid component> Terephthalic acid 90 55 30 40 Isophthalic acid 90 40 55 30 Cyclohexanedicarboxylic acid 20 5-sodium sulfoisophthalic acid 10 10 5 15 10 <polyvalent hydroxy component> ethylene glycol 80 90 70 35 70 diethylene glycol 20 10 10 15 5 triethylene glycol 1,4-butanediol 20 neopentyl glycol 45 cyclohexane Dimethanol 25──────────────────────────────────── (aqueous epoxy group-containing compound) aqueous Epoxy group-containing compounds B1, with B2.

The contents (main components) are as follows. B1: tetraglycerol tetraglycidyl ether B2: sorbitol triglycidyl ether (aqueous acryl) polyacrylic resin compound aqueous dispersion C
1 was used.

C1: 45 mol% of methyl methacrylate,
A copolymer (aqueous polyurethane) composed of 30 mol% of n-butyl acrylate, 20 mol% of styrene, and 5 mol% of acrylic acid was used. D1: Aqueous dispersion of polyester-based polyurethane resin having a carboxylic acid group “Hydran APX-101” (trade name, manufactured by Dainippon Ink and Chemicals, Inc.) (Melamine compound) Melamine compound E1 was used.

E1: Water-soluble melamine compounds centering on mononuclear, dinuclear, and trinuclear compounds of almost tetrafunctional methylol or methoxymethyrol melamine Examples 1 to 11 and Comparative Examples 1 to 15 On the polyester film shown in Table 4 below, the coating layer also shown in Table 4 was provided.
However, the numerical values indicating the ratio of the aqueous polyester and the aqueous epoxy group-containing compound in the coating layer in the table mean the weight ratio (% by weight) based on the dry weight of each coating agent. The thickness of the coating layer is the thickness on the finally completed film.

Comparative Examples 16 and 17 As shown in Table 4, each white polyester film was not provided with a coating layer. The evaluation results of the obtained films are shown in Table 5 below.
It writes in.

[0071]

[Table 7]

[0072]

[Table 8] Next, the evaluation results of each example are shown in Table 5 below. In the table, "-" in the column of evaluation of photographic paper practical characteristics means that evaluation was not performed due to insufficient adhesion to the photographic image forming layer.

[0073]

[Table 9]

[0074]

[Table 10]

[0075]

According to the present invention described above, a polyester-based photographic printing paper support provided with a coating layer having good adhesion to a photographic image forming layer can be easily provided. The industrial value of is very large.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI G03C 1/795 G03C 1/795

Claims (4)

[Claims] 1. An aqueous polyester and an aqueous epoxy group-containing compound in a dry weight ratio of 30/70 to 90/1.
The coating solution containing the coating solution at a ratio of 0 has an opacity (OD) of 0.3.
A method for producing a support for polyester-based photographic printing paper, wherein the support is applied to at least one side of a white polyester film having a b value of less than 2.0 and dried. 2. The method for producing a support for a polyester-based photographic printing paper according to claim 1, wherein the white polyester film contains a white pigment. 3. The polyester system according to claim 1, wherein the white polyester film has an apparent density (ρ) of 0.6 to 1.2 g / cm ³ and contains closed cells inside the film. A method for producing a photographic paper support. 4. The method for producing a support for a polyester-based photographic printing paper according to any one of claims 1 to 3, wherein the application is performed in a production process of the polyester film.