JPH02234153A - Photographic support - Google Patents

Abstract

PURPOSE:To prevent deterioration of paper strength at the time of exposing it with electron beams due to the hardening of the opaque resin layer by incorporating in the paper support a specified amount of resin having a glass transition point of >=100 deg.C in the paper support and hardened with electron beams and coating it with a resin containing a white pigment. CONSTITUTION:The paper support contains the electron-beam hardened resin having a glass transition point of >=100 deg.C in an amount of 10 - 30wt.% of the paper support, and it is coated with the opaque resin layer comprising the white pigment and electron beam hardenable resin or the molten polyolefin resin containing the white pigment and polyolefin resin, and the like, thus permitting deterioration of paper strength to be prevented even when the paper is exposed to electron beams by forming the opaque resin layer.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a support for photographic paper.
More specifically, the present invention relates to a water-resistant photographic support comprising a paper support containing an electron beam-cured resin having a glass transition temperature of 100°C or higher, and the paper support being coated with a resin containing a white pigment. CB) Prior Art In recent years, waterproof paper, in which a polyolefin resin layer into which a white pigment has been kneaded is provided on the surface of the base paper that is the support, has been mainly used as a photographic support. The main reason for providing a polyolefin resin layer on the base paper in this way is to prevent processing chemicals from penetrating into the base paper during development.This coating layer makes it possible to shorten the development time, and also Since no processing chemicals remain inside, yellowing due to aging can be avoided. Coating base paper with such polyolefin resin is generally done using a melt extruder. Furthermore, inorganic white pigments such as titanium dioxide are mixed into the polyolefin resin layer on the surface of the photographic paper to improve the hiding power and whiteness of the photographic support and to improve the resolution of the photographic paper. It's included. [C] Problems to be Solved by the Invention However, polyolefin resins have extremely high viscosity even when melted, making it difficult to disperse inorganic pigments such as titanium dioxide, and the types of polyolefin resins that can be used are limited. Ta. Furthermore, there is a limit to the filling rate of inorganic pigments, and in order to obtain a certain degree of hiding power and whiteness, it is necessary to increase the resin thickness. Furthermore, since such melt extrusion coating of polyolefin resin is performed at a temperature higher than the thermal decomposition temperature of the polyolefin resin, yellowing and pinholes occur in the resin layer due to thermal decomposition of the resin. moreover,
As the extrusion speed increases, the adhesion to the base paper decreases, causing a problem in the quality of the final product. In the production of resin-coated photographic supports, melt extrusion allows the thinning of opaque resin coating layers while maintaining adequate hiding power, and the ability to increase coating speed without degrading quality. For example, an electron beam curable resin (hereinafter referred to as an electron beam curable composition) in which a white pigment is kneaded is coated on base paper for photographic printing paper, which is difficult to apply. A method of manufacturing a water-resistant photographic support by forming an opaque resin coating layer has been proposed (for example, Japanese Patent Publication No. 17104/1983). In this method, a coating liquid in which a white pigment is dispersed at a high concentration in a resin such as acrylate ester that has unsaturated bonds that can be polymerized by electron beam irradiation is applied onto the base paper for photographic paper, and then polymerized by electron beam irradiation at room temperature. Since this method involves crosslinking and forming an opaque resin coating layer on the surface of the base paper, the opaque resin coating layer can be made thinner without reducing the hiding power, and yellowing of the resin due to the melt extrusion method and the formation of bottle holes. ,
It is now possible to produce water-resistant photographic supports without deteriorating the quality of the final product due to poor adhesion of the resin layer, blocking, or matte finish. However, in the production of photographic supports using electron beam curable compositions, when the opaque resin coating layer highly filled with white pigment is thinned and processed at high speed, no unreacted electron beam curable resin remains. As such, a certain amount of excessive electron beam irradiation is required. This is an unreacted electron beam curable resin in the opaque resin coating layer. This is because if oil is present, the development reagent will be incorporated into the opaque resin coating layer after development and will cause coloration. Such excessive electron beams reach the base paper layer located below the opaque resin coating layer, but at this time, the cellulose fibers that make up the base paper are also cut, reducing the interpaper strength. In addition, this decrease in paper-to-paper strength also affects the dimensional stability of the photographic support, and when using a paper support that has been irradiated with an electron beam on one shell, the tensile strength decreases and it tends to stretch during development. Become. Therefore, photographic paper made by this method has serious problems such as a decrease in adhesive strength with the opaque resin coating layer after development, impairing adhesion, and high elongation. Furthermore, in recent years, photographic paper has been increasingly used especially for panels, postcards, and stickers, and thin supports for photographic paper are generally used for these purposes. However, depending on the molten polyolefin resin or electron beam curable resin composition that forms the opaque resin coating layer, there is a problem in that it shrinks significantly during cooling or curing, causing curling in the photographic paper support used as the product. ．． This curling problem is particularly likely to occur in thin photographic paper supports such as those mentioned above, and has been a factor that extremely limits the range of resins that can be selected to form the opaque resin coating layer. CD) Means for Solving the Problems As a result of intensive research into means for solving the above-mentioned problems, the inventor has found the following solution. That is, an electron beam-cured resin having a glass transition temperature of 100° C. or higher is contained in the paper support in an amount of 10 to 30% by weight based on the weight of the paper support, and This is an invention of a photographic support characterized in that an opaque resin coating layer containing a white pigment is provided on the support. Making a photographic paper using the photographic support according to the invention,
When a development test was carried out and the adhesive strength of the photosensitive emulsion layer was measured, it was found that both the emulsion layer and the opaque resin coating layer had extremely good adhesive strength and good adhesion. Furthermore, the present invention surprisingly had the unexpected effect of suppressing the decrease in tensile strength of paper, which is unavoidable in the process of curing resin by electron beam irradiation using paper as a support. In addition, it has good curl characteristics, and even if an opaque resin coating layer made of either a molten polyolefin resin or an electron beam curable composition is provided on a relatively thin (100,000 nm or less) paper support, the curl balance can be maintained. It has been found that the present invention provides a support for photographic paper that is easy to use and of excellent quality. In the present invention, the opaque resin coating layer is an electron beam curable composition layer consisting of a white pigment and an electron beam curable resin, or a molten polyolefin resin layer consisting of a white pigment and a polyolefin resin. When a molten polyolefin resin is applied to an opaque resin coating layer, a paper support containing the electron beam curable resin of the present invention is used to form a polyolefin resin coating layer, which is then cured by electron beam irradiation. It was found that this photographic support has extremely good adhesion strength to the paper support and is less likely to be penetrated by developer. The present invention will be explained in detail below.

In the present invention, in order to contain an electron beam curable resin whose electron beam cured product has a glass transition temperature of 100°C or higher in the paper support, the electron beam curable resin is added to what is called white water in the paper industry from the papermaking stage. One method is to disperse the resin and adsorb it to the cellulose fibers, the other is to adsorb it to the cellulose fibers by soaking it with a means such as a tab after the paper making process, and the paper support method after dissolving the electron beam curable resin in a solvent such as acetone. There are three methods: applying it to the body, impregnating it, and drying it.6 In these cases, the electron beam curable resin can be used alone, dissolved in a solution, or in the form of an emulsion to improve the content. Can be done.

It is essential for the electron beam curable resin used for inclusion in the present invention that the glass transition temperature of the cured product is 100°C or higher, and in addition, electron beam curable properties, weather resistance, film strength, heat resistance, It can be selected in consideration of conditions such as adsorption and adhesion to the support. Further, the electron beam curable resin used for inclusion may be contained in an amount of 10 to 30% by weight based on the weight of the paper support before providing the back side water-resistant resin layer and the front opaque resin coating layer. If it is less than this ratio, the expected dimensional stability and curl prevention effect cannot be obtained, and if it is more than this ratio, not only will the dimensional stability and curl prevention effect not be affected, but the resin contained will be cured. This increases the amount of electron beam irradiation required to achieve this, which is uneconomical.

The electron beam curable resin that forms the opaque resin coating layer has the following characteristics: electron beam curing properties, strength properties, high concentration dispersion of white pigment, weather resistance, film strength, heat resistance, curling properties, adhesion to the support, and photosensitivity. It can be selected taking into consideration conditions such as adhesion with the emulsion layer. Examples of electron beam curable resins include unsaturated polyesters having electron beam reactive groups at the molecular ends or side chains, modified unsaturated polyesters, acrylic polymers, and monomers having unsaturated bonds alone or in combination with other Can be used with solvents. Typical types of electron beam polymerizable resins are illustrated below. (A) monofunctional acrylate,
Monofunctional methacrylate (B) Polyfunctional acrylate, polyfunctional methacrylate, polyfunctional oligomer (C) Polyester acrylate, polyester methacrylate (D) Eboxy acrylate, epoxy methacrylate (E) Urethane acrylate, urethane methacrylate, (F) Polyol acrylate, polyester All methacrylate As a result of our research on photographic supports irradiated with electron beams, we found that among the above electron beam curable resins,
If the paper support contains a certain proportion of acrylate resin with good crosslinking properties and the glass transition temperature of the electron beam cured product is 100°C or higher and is cured by electron beam irradiation, the interpaper strength after electron beam irradiation will be increased. It was found that the dimensional stability was improved, and the curling properties were significantly improved. Contains an electron beam curable resin whose glass transition temperature is lower than 100°C, so that even when cured by electron beam irradiation, it provides the expected interpaper strength and also improves the dimensional stability of the support. , it was found that it had no significant effect on curl characteristics. However, even if an electron beam curable resin has a glass transition temperature lower than 100°C when used alone, it cannot be cured by electron beam when mixed with an electron beam curable resin having a sufficiently high glass transition temperature. It was also discovered that if the glass transition temperature of a material is 100°C or higher, it can be used as a containing resin. Examples of the white pigment in the electron beam curable composition used in the present invention include rutile-type or anatase-type titanium dioxide, zinc oxide, talc, calcium carbonate, barium carbonate, barium sulfate,
White pigments such as calcium sulfate and silica can be used untreated or after surface treatment with siloxane, alumina, alcohol, etc. The proportion of the white pigment in the electron beam curable composition is preferably from 20% to 80% by weight, particularly preferably from 20% to 70% by weight. This means that if the proportion of the white pigment is extremely small, it will not have the expected hiding power, and if it is too large, it will not only lack the ability as a binder for the electron beam curable resin but also reduce the amount of electron beam irradiation. This is because it causes an increase in the amount of water and has an undesirable effect on the base paper for photographic paper or the coated resin that has been formed. The electron beam curable composition of the present invention contains pigments and dyes such as ultramarine blue and cobalt violet, which are used in the surface polyethylene layer of photographic supports prepared by conventional polyolefin resin melt extrusion methods, and antioxidants. agent,
Various additives such as optical brighteners, antistatic agents, dispersants, and stabilizers can be added in appropriate combinations. The base paper used as a support in the present invention can be ordinary natural pulp paper, synthetic fiber, or so-called synthetic paper made of artificial paper of synthetic resin film, but wood of softwood pulp, hardwood pulp, softwood mixed pulp Natural pulp paper, whose main component is pulp, is advantageously used. There is no particular restriction on the thickness of the paper support, and its basis weight is preferably 50 g/m'' to 250 g/m''. The paper support mainly composed of natural pulp, which is advantageously used in the method of the present invention, can contain various polymeric compounds and additives. For example, starch derivatives, polyacrylamide, polyvinyl alcohol derivatives,
Dry paper strength enhancers such as gelatin, sizing agents such as fatty acid salts, rosin derivatives, dialkyl ketene dimer emulsions, wet paper strength enhancers such as melamine resins, urea resins, and eboxidized polyamides, stabilizers, pigments, dyes, oxidation Inhibitors, optical brighteners, various latexes, inorganic electrolytes, pH adjusters, etc. can be contained in appropriate combinations. Furthermore, in the present invention, even if the surface of the paper support is subjected to surface treatment such as corona treatment in order to improve the adhesion and wettability between the paper support and the opaque resin coating layer, the electron beam curable composition and the photosensitive emulsion In order to improve adhesion and wettability with the resin, surface treatments such as corona treatment or sub-coat may be applied to the surface of the resin. Further, on the back side of the photographic support of the present invention, a film can be formed by coating a polyolefin resin by the conventional melt extrusion method or by applying an electron beam curable resin and then irradiating it with an electron beam. A resin coating layer can be formed by this method, and a back coat layer can be provided to provide writing properties on the back side. A general pigment kneading machine can be used to prepare the electron beam curable composition. For example, two-roll, three-roll, ball mill, twenty-one goo, high-speed mixer,
It is a first class homogenizer. Examples of methods for applying the electron beam curable composition onto the paper support include blade coating, doctor coating, air knife coating, spray coating, squeeze coating, reverse roll coating, gravure roll and transfer roll coating, and extrusion coating. , curtain coating, etc. are used,
It is also possible to smooth the paper support using a calender or the like after incorporating the electron beam curable resin into the paper support.

The polyolefin resins used in the present invention include homobolymers of olefins such as polyethylene, polypropylene, polybutene, and polypentene, copolymers of two or more olefins such as ethylene/brobylene copolymers, and mixtures thereof; Polyethylene is advantageously used. The thickness of the opaque resin coating layer made of an electron beam polymerizable composition or molten polyolefin resin varies depending on the type of base paper and the filling rate of white pigment, but is 2 to 100 μm, more preferably 3 to 50 μm, and is thinner than this thickness. However, it is difficult to obtain a sufficient whiteness and opacity in terms of whiteness and opacity, and it is difficult to coat the coating uniformly.If the coating layer is thicker than this, it is not preferable in terms of quality. When using an electron beam curable composition, if the surface of the photographic support is to be further mirror-finished or patterned, the surface to be treated is brought into contact with a mirror-finished roll or a patterned roll, and the electron beam is irradiated from the back of the surface to cure it. A mirror finish can be applied. Another method is to perform preliminary electron beam irradiation in advance to partially harden the surface, and then bring it into contact with a mirror roll or molding roll and perform secondary irradiation to completely harden it. When using molten polyolefin resin, a mirror or patterned surface can be obtained by using a corresponding cooling roll. In the present invention, the electron beam curable resin contained in the paper support can be cured by electron beam irradiation before or after providing the opaque resin coating layer containing a white pigment. When the opaque resin coating layer containing a white pigment is made of an electron beam curable resin composition, it can be cured simultaneously with the contained electron beam curable resin by one irradiation. For electron beam irradiation, the acceleration voltage is 10 from the viewpoint of penetrating power and curing power.
0 to 1000 kV, more preferably 100 to 30
Using a 0kV electron beam accelerator, the absorbed dose in one pass is 0.
．． It is preferable to set it to 5 to 2Q Mrad. If the accelerating voltage or electron beam irradiation amount is lower than this range, the penetrating power of the electron beam will be too low and sufficient curing will not occur.
Moreover, if it is too large than this range, not only will energy efficiency deteriorate, but also unfavorable effects will appear on quality, such as a decrease in the strength of the paper support and decomposition of resin and additives. The electron beam accelerator may be, for example, an electrocurtain system, scanning type, double scanning type, etc. In addition, during electron beam irradiation, if the oxygen concentration is high, curing of the electron beam curing resin will be hindered, so replacement with an inert gas such as nitrogen, helium, carbon dioxide, etc. is performed to reduce the oxygen concentration to 6.
00 ppm or less, preferably 400 ppm
It is preferable to irradiate in an atmosphere that is controlled as follows. The purpose of containing an electron beam curable resin in the paper support according to the present invention is to suppress the decrease in interpaper strength that occurs when the paper support is irradiated with an electron beam, improve dimensional stability, and coat the paper support with an opaque resin. This is to improve the curling characteristics when a layer is provided, and is not particularly concerned with controlling mass transfer after curing. If the paper is reinforced with opaque resin, there is no need for the electron beam curable resin contained in the paper to form a film without holes, and there is no problem even if the bulb fibers that make up the paper support come into direct contact with the opaque resin coating layer. Further, on the opaque resin coating layer of the photographic support prepared according to the present invention, smoothness, water resistance, chemical resistance, easy cleaning properties, and adhesion with the photosensitive emulsion layer on the outermost surface of the photographic support,
A coating layer of polyolefin resin may also be provided to impart properties such as antifogging properties to the photosensitive emulsion. Furthermore, a primer layer may be provided between the paper support and the opaque resin coating layer to even out the unevenness of the paper support.
The primer layer may contain a white pigment. The photographic support prepared according to the present invention can be used as photographic paper by coating a photosensitive emulsion thereon. [E] Function The photographic support produced in the present invention contains an electron beam curable resin with good crosslinking properties at least on the surface of the paper support, so it is difficult to cure the opaque resin coating layer. A high-quality photographic support that does not reduce interpaper strength even when exposed to electron beam irradiation, improves the dimensional stability of the paper support, and maintains good adhesion with the opaque resin coating layer. can be obtained. (F) Examples The present invention will be explained in detail below using examples, but the content of the present invention is not limited to the examples. Example 1 An average weight of 10 g/m of trimethylolpropane triacrylate (Tg of cured product: 250°C or higher) dissolved in acetone as an electron beam curable resin was applied to the surface of a photographic base paper with a basis weight of 100 g/m''. It was impregnated with a tab press so that the thickness of
m) The electron beam curable resin contained in the paper was guided into an electron beam irradiation device (Curetron, manufactured by Nissin High Voltage Co., Ltd.) and irradiated with electron beams under the conditions of an acceleration voltage of 220 kV and an absorbed dose of 2 Mrad. hardened. Low density polyethylene (density 0.9
The laminate was coated with an equal mixture of 18 g/cm', Ml 5) and high density polyethylene (density Q, 965 g/cm3, MI 7) to an average thickness of 12 μm. After corona treatment was performed on the surface of the obtained resin-containing paper support, an electron beam curable composition having the following composition was applied to an average thickness of 8 μm.
2 Mra using an electron beam irradiation device.
A photographic support was obtained by curing by irradiation with electron beam (d). (Electron beam curable composition) Rutile type titanium dioxide 50% by weight Electron beam curable resin 50% by weight Electron beam curable resin and rutile type titanium dioxide were mixed using a triple roll. The electron beam curable resin used was a mixture of equal amounts of α,ω-tetraacryloyl(bistrimethylolproban) monotetrahydride phthalate and trimethylolbroban triacrylate. Example 2 α, ω dissolved in a7ton on a paper support similar to Example 1
- Tetraacryloyl(bistrimethylolpropane) monotetrahydrophthalate and polyoxyalkylene (
, C2-3) and sphenol A/diacrylate (Tg of cured product; 105°C) at a ratio of 30 g/m'' using a solvent coater, and then dried with hot air. As in Example 1, the back surface was laminated with polyethylene, and the surface was coated with low-density polyethylene (density 0.918 g/cm3, MI 1
8.5> 30 parts of a masterbatch kneaded with 30% by weight of titanium oxide, low density polyethylene (density α9 1
8 g/am3, MI5) 45 parts, high density polyethylene (density 0.96 5 g/Cm3, MI 7) 25
A resin composition consisting of 300 ml of resin was laminated and coated with a thickness of 20 μm. After that, the absorbed dose is 4 from the opaque resin coating layer side.
A photographic support was obtained by curing the electron beam curable resin by irradiating it with an electron beam so that it became Mrad. Example 3 Tris(2-hydroxyethyl)isocyanuric acid acrylic ester (Tg of cured product: 166°C) was applied as an electron beam curable resin to the surface of the same paper support as in Example 1 at 208° C.
/m2, low density polyethylene (density 0.918 g/c+a', M
I5) 75 parts, high density polyethylene (density CL 9 6
5 g/cm', MI7) was laminated to a thickness of 7 μm. After the corona treatment, the same electron beam curable composition as in Example 1 was applied as an opaque resin coating layer, and the electron beam curable composition was cured by electron beam irradiation at an absorbed dose of 4 Mrad. A photographic support was obtained by curing the composition. Comparative Example 1 A photographic support was obtained in the same manner as in Example 1 except that the proportion of the electron beam curable resin was 3 g/m2. Comparative Example 2 A photographic support was prepared in the same manner as in Example 2, except that the electron beam curable resin for inclusion was changed to 8 mol of propylene oxide modified pentaerythritol tetraacrylate whose Tg of the cured product was 0°C or less. I got it. Comparative Example 3 A photographic support was prepared in the same manner as in Example 3, except that the electron beam curable resin to be contained was changed to 8 mol of brobylene oxide-modified pentaerythritol tetraacrylate whose Tg of the cured product was 0°C or less. I got a body. Comparative Example 4 A photographic product was prepared in the same manner as in Example 3, except that the electron beam curable resin for inclusion was changed to polyoxyalkylene (02-3) bisphenol A diacrylate whose cured product had a Tg of 75°C. I got a support. A photographic support was obtained in the same manner as in Example 3, except that the electron beam curable resin used in Comparative Example was changed to tripropylene glycol diacrylate whose cured product had a Tg of 90°C. The photographic supports obtained in Examples and Comparative Examples were
After corona treatment, a color silver halide photographic emulsion was coated and hardened in the usual manner to produce photographic paper, and after a series of development treatments, adhesion was measured. Adhesion was measured by making cuts in a grid pattern with a razor on dried photographic paper, pressing a standard adhesive tape onto the cut, and then instantly peeling it off to determine the surface condition of the photographic paper. (Peeling of emulsion layer, opaque resin coating layer, base paper, etc. B) was evaluated. The dimensional stability of photographic paper was judged especially from the relationship between the tensile strength and elongation of the support when wet. Curl characteristics are determined at 20'C and humidity 5 after development.
Evaluation was made based on the average curl height at the four corners of a photographic paper support that was left in an atmosphere with a controlled humidity of 0%. Table 1 summarizes the results regarding the adhesion, dimensional stability, and curl of the photographic supports prepared in Examples and Comparative Examples. (Margin below) Table 1 Good adhesion can be maintained. In addition, the electron beam curable resin contained in the paper support improves dimensional stability and curling, making it possible to obtain a high-quality photographic support, and as a result, high-quality photographic paper can be produced. ．． CG) Effect of invention

Claims (3)

[Claims] (1) The electron beam-cured resin with a glass transition temperature of 100°C or higher is contained in the paper support at a rate of 10% by weight based on the weight of the paper support.
1. A photographic support, characterized in that the opaque resin coating layer containing a white pigment is provided on the paper support. (2) The photographic support according to claim 1, further comprising a primer layer made of a melt-extruded polyolefin resin between the opaque resin coating layer and the paper support. (3) The photographic support according to claim 1 or 2, wherein the opaque resin coating layer is composed of a white pigment and an electron beam curable resin, and is a layer cured by electron beam irradiation.