JPH06175361A - Image forming material - Google Patents

Abstract

PURPOSE:To provide an image forming material which has equal properties such as solid-density, chromatic value, storage property of the material, resolution of image, transparency, and trapping property, to a conventional prepress proof using an azo-based pigment and moreover, causes-no blocking. CONSTITUTION:This material has a photocrosslinking resin layer on a substrate and this resin layer is colored and can be transferred. By an image-exposure, only the exposed area is changed into a non-transfer area, and unexposed area is transferred to an image receiving body to form an image. The coloring agent incorporated into the photocrosslinking resin layer is an isoindoline-based pigment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming material, and more specifically, it is formed by superimposing a single color or a multicolor by utilizing the difference in adhesiveness between exposed and unexposed areas of a photosensitive layer. The present invention relates to a high-quality image forming material which can be used as a color proof surprint prepress proof to obtain a transfer material that is quite similar to a printed material.

[0002]

2. Description of the Related Art Conventionally, in the field of printing industry, it is generally known to use proof printing or prepress proof as a means for confirming the finish, color tone and the like of a finally printed printed matter before printing. There is. Prepress proof has the advantage that the final printed product can be predicted without the use of printing ink.Overlay method and surprint method can be used according to the final image quality and various purposes in the plate making and printing process. Different methods are used. The overlay method has a photosensitive layer containing a coloring material corresponding to each color separation mask on the transparent base film,
The film and the mask are brought into close contact with each other, exposed and developed, and the films are superposed on each other for calibration. Nowadays,
For example, a new method that does not use a developing solution or a developing gas, such as Japanese Patent Laid-Open No. 63-188088, has been considered. However, in this method, transmitted light must be used, so that the cost is low from the beginning. Subtle color impression, color balance, and gradation are impaired, and it is not possible to judge the finish of printed matter as general commercial printed matter or high-quality art printed matter.

Unlike the overlay method, the surprint method can obtain a hard copy, and thus has a high utility value. So far, for example US Pat. No. 3060023,
It is known that a photopolymer photosensitive layer consisting of several layers is laminated on a single support as described in JP-A Nos. 3060024 and 3060025 to sequentially form color separation images. In this example, color toner is used as the coloring substance, and it can be said that the prepress proof is excellent in that it faithfully reproduces the original mask, but since the photosensitive layers are laminated, diffuse reflection in non-image areas becomes large. As compared with the actual printed matter, the gloss is remarkably high and the texture is quite different. Further, the cured layer after exposure is fragile, and tears are easily formed on the surface depending on storage conditions. Moreover,
Coloring with a color toner is not preferable in terms of work hygiene because the color toner is scattered.

There is also a prepress proof which can be used for both the overlay method and the surprint method as described in JP-B-3-71707 and JP-A-61-188537. The advantages of this method are:
Depending on the purpose of use, if you just want to check characters, etc., you can check only by overlay, and if you want to get a hard copy for checking subtle color parts such as pictures,
It is highly versatile in that it can be transferred to a transfer target. However, there is a drawback that the working environment is deteriorated because a developing process using an organic solvent is required. Furthermore, since there is a photosensitive transparent intermediate layer for adhering the transferred material and the colored photosensitive layer, the reflected light is diffusely reflected, and after all, it is a finish that is far from the actual printed matter and was obtained. The density of the transfer material tends to be lower than that of the actual printed material. Further, since the thickness of the transferred photosensitive layer is a constant thickness, it is stable as a photosensitive material, but the color tone cannot be changed as a prepress proof, so that the finish is not as good as the actual printed matter. Will end up.

The present inventor has formed a photosensitive layer containing a dye and / or a pigment on a transparent support and exposed the image to give a difference in tackiness between the exposed portion and the unexposed portion of the photosensitive layer during transfer. And invented an image forming material for transferring an image to an image receptor such as paper, and filed a patent application (JP-A-63-147154, JP-A-63-147162).
Issue, JP-A-1-172957, USP 5,05
5,375, etc.). The prepress proof obtained by transferring the image to the image receptor by cohesively breaking the photosensitive layer between the image forming material and the roll nip is completely different from the conventional prepress proof. It has been found that the same image and texture as an actual printed matter can be reproduced because there is no layer such as an adhesive layer between them. However, after the image-forming material is image-exposed, when the image is transferred to a pre-heated transfer target while peeling the protective film from the image-forming material, the image-forming material is subjected to heat and unexposed to the photosensitive layer. There was a case where so-called blocking occurred, in which a part of the part was transferred to the protective film. If the blocked image forming material is directly transferred to the transfer target, the originally transferred portion will not be transferred, so that the original cannot be faithfully reproduced.

In particular, in order to obtain a prepress proof from an image-forming material, a general-purpose pigment used in an offset ink or a gravure ink can be used to obtain the same quality as the actual printed matter, but especially Process Yellow. Among them, the azo pigment was particularly prone to blocking. Addition of wax, silicone compound, etc. to prevent blocking has some effect, but this kind of additive emerges on the surface of the photocurable layer after transfer,
There is a problem that it adversely affects the next color transfer.

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the above-mentioned image forming material, the present invention has a prepress proof using a conventional azo pigment, particularly for yellow among process colors. An image forming material having the same solid density, color value, storability of material, image resolving power, transparency, trapping, etc., which does not cause blocking.

[0007]

SUMMARY OF THE INVENTION The present invention comprises:
A material for forming an image by having a transferable colored photocrosslinkable resin layer, rendering only an exposed portion non-transferable by image exposure, and transferring an unexposed portion to an image receptor. The image forming material is characterized in that the colorant contained in the photocrosslinkable resin layer is an isoindoline pigment. The support of the present invention is preferably a sheet or film material that is stable to heat, chemical light, etc. and that sufficiently transmits actinic rays. For example, it is a film or sheet of cellulose acetate, polystyrene, polyvinyl chloride, polyethylene terephthalate, polycarbonate, polypropylene or the like. Polyethylene terephthalate is particularly preferable in terms of transparency, thermal stability, dimensional stability and the like. The thickness of the sheet or film used for the support is preferably 9 to 25 μm.

The material applied to the photocrosslinkable resin layer of the present invention is a photopolymerizable compound and a colorant, and in some cases, includes a thermoplastic resin having no photopolymerizability. Further, a photopolymerization initiator, a photopolymerization accelerator, a thermal polymerization inhibitor, a resin plasticizer, a pigment dispersant and the like are used in combination as additives. As the photopolymerizable compound, any compound selected from a monomer, a polymer and a prepolymer can be used, but preferably,
A material that can plasticize a thermoplastic resin at room temperature is used.
Typical examples of the photopolymerizable compound include 2-hydroxyethyl (meth) acrylate, ethylene glycol diacrylate, diethylene glycol diacrylate,
1,6 hexanediol di (meth) acrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, dipentaerythritol hexaacrylate, etc. are available. These ethylenically unsaturated compounds may be used alone or in combination of two or more as necessary. Good.

As the thermoplastic resin, a polymer which is thermoplastic and has excellent compatibility with a photopolymerizable compound and which does not have photopolymerizability can be used. For example, polyvinyl chloride, poly (meth) acrylic acid ester, epoxy resin, polyurethane resin,
Cellulose derivative (for example, ethyl cellulose, cellulose acetate, nitrocellulose), vinyl chloride-vinyl acetate copolymer,
Polyamide resin, polyvinyl acetal resin, diallyl phthalate resin, butadiene-acrylonitrile copolymer and the like are available, and one or more of these polymers may be used depending on the required physical properties. As the photopolymerization initiator, those having a small absorption mainly in the visible light portion,
Those having good compatibility with the photopolymerizable compound and those having photochemical intersystem quantum efficiency close to 1 are preferable. For example, benzophenone, benzoin ethyl ether, benzyl dimethyl ketone, azobisisobutyronitrile, 2-chlorothiozanzone, 2-methylthiozanzone, 2-ethylthiozanzone, 2-isopropylthiozanzone, 4 '
-Isopropyl-2-hydroxy-2-methylpropiophenone and the like, and may be used in combination with a photopolymerization accelerator in order to increase the photopolymerization initiation efficiency. Aromatic-aliphatic tertiary amines and the like are known as this photopolymerization accelerator. For example, Michler's ketone, 4,4′-bisdiethylaminobenzophenone and the like are available. The accelerator is
Depending on the substance, it may turn yellow, and therefore it is selected in consideration of the acceleration efficiency, yellowing, compatibility with the initiator, the energy of the actinic ray to be used, and the wavelength range.

The thermal polymerization inhibitor has an action of suppressing radicals in a thermal amount in an amount that does not interfere with radical generation for photopolymerization. As such a thermal polymerization inhibitor, an aromatic derivative can be used, and examples thereof include hydroquinone, p-methoxyphenol, t-butylcatechol,
Although there are pyrogallol and the like, combinations other than the above may be used. The colorant blended in the photocurable resin layer of the present invention,
An isoindoline pigment. The isoindoline pigment is a pigment obtained by condensing 1,3-diiminoisoindoline and an active methylene compound, and is, for example, C.I. I. Pigment Yellow 139. As the colorant of the present invention, dyes and pigments other than those described above can be used in combination in order to obtain the required hue, as long as the object of the present invention is not impaired. The preferred composition of the photocrosslinkable resin layer is 0.1 to 70 parts by weight of the photopolymerizable compound, more preferably 30 to 50 parts by weight of the thermoplastic resin 20 to 70 parts by weight of the photopolymerization initiator 3 to 10 parts by weight. Agent 0.0001 to 0.002 parts by weight Colorant 0.1 to 10 parts by weight, more preferably 3 to 7 parts by weight.

In the photocurable resin layer of the present invention, a composition containing a photopolymerizable compound, optionally a thermoplastic resin, a pigment and a photopolymerization initiator and other additives is formed on a support to give a dry coating film thickness 1
It can be formed by coating in the range of 3 μm. An organic solvent may be added to the composition in order to obtain coatability. In the image forming material of the present invention, a protective film is usually laminated on the photocurable resin layer. The protective film may be composed of a single layer or a plurality of layers, but the surface in contact with the photosensitive layer has few fish eyes and has good releasability from the resin layer so that unnecessary plasticizer does not precipitate. Is preferred. The surface that secures the gas barrier property may be the surface that directly contacts the resin layer or may not directly contact the resin layer. For example, as a gas barrier plastic film, a film containing polyvinyl alcohol or ethylene vinyl alcohol as a layer can be used. For the purpose of ensuring the rigidity of the image forming material, it may be a protective film in which a surface having no direct contact with the resin layer is lined with another material having strong rigidity. In the image forming method relating to the image forming material of the present invention, a positive mask is brought into close contact with the support side, and ultraviolet rays are irradiated to perform image exposure. The viscosity of the resin in the exposed area in the photocrosslinkable resin layer changes due to the crosslinking reaction due to the irradiation of ultraviolet rays. Next, the positive mask is removed, the protective film is peeled off, the resin layer is used as a transfer surface, and an unexposed portion of the resin layer is transferred to the image receptor by applying a superposing pressure on the image receptor such as paper. The transfer is preferably performed while the image receptor is heated. The preferred temperature for transfer is 50 to 100 ° C. In the case of a process color image, for example, a prepress proof, the yellow image forming material according to the present invention may be transferred, and then the image may be formed using the image forming materials having magenta and cyan colors. Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto. In the examples, “part” means “part by weight”.

Example 1 A photosensitive layer liquid having the following composition was prepared. Diallyl isophthalate (prepolymer manufactured by Daiso Co., Ltd.) 11.4 parts Kayarad DPHA (Nippon Kayaku Co., Ltd. dipentaerythritol hexaacrylate 7.1 parts Kayarad TPGDA (Nippon Kayaku Co., Ltd. tripropylene glycol dia) Crylate 0.9 parts Irgacure 907 (Nippon Ciba Geigy Co., Ltd. photopolymerization initiator) 1.2 parts Kayacure DETX-S (Nippon Kayaku Co., Ltd. photopolymerization initiator) 0.6 parts Irgacure 369 (Nippon Ciba Geigy) Photopolymerization initiator) 0.2 parts Solspers 24000GR (pigment dispersant manufactured by ICI Japan Co., Ltd.) 0.1 part KP-604 (silicone acrylate macromer manufactured by Shin-Etsu Chemical Co., Ltd.) 02 parts Pariotor Yellow D-1155 (Isoindori manufactured by BASF Japan Ltd.) Pigment CI Pigment Yellow 185) 2.8 parts Pariotor Yellow D-1819 (isoindoline pigment CI Pigment Yellow 139 manufactured by BASF Japan Ltd.) 0.5 part p-methoxyphenol (polymerization inhibitor) ) 0.18 parts Methyl ethyl ketone 75.0 parts A protective film was prepared in the following manner: OPP Trefan 2372 (Toray Industries, Inc. polypropylene film;
A thickness of 8 μ) and Lumirror # 100 (polyester film manufactured by Toray Industries, Inc .; thickness of 100 μ) T type were dry laminated through an adhesive to obtain a protective film. The colored photosensitive layer formed on the transparent support and the polypropylene film surface of the protective film were superposed and laminated with a laminator to obtain an image forming material.

The transparent support side of this image forming material and the silver salt surface of the original positive mask were adhered to each other, and a UV printer, DS-
P-647-GA (manufactured by Dainippon Screen Mfg. Co., Ltd.) was applied with an actinic ray of 10 mj / cm ² . The image forming material and the original positive mask were peeled off, and the protective film was peeled off. Transfer was performed by using a fast laminator 8B-700 special type (manufactured by Taisei Laminator Co., Ltd.) to bring the SK coat (Sanyo Kokusaku Pulp Co., Ltd. coated paper) and the image forming material from which the protective film was peeled off into contact with each other, and pressure 4 kg / Cm
² , passing speed 35cm / min, roller surface temperature 70
When transferred by the nip between the rollers under the condition of ℃,
It was possible to obtain a transfer product in which the thickness of the photosensitive layer in the unexposed portion was 2.0 μm and transfer was performed without blocking on the entire transfer surface and the material feeling was completely the same as that of an ordinary printed product.

Further, this image forming material is set at a set temperature of 40.degree.
Stored in a thermostat for 1 year, imagewise exposed under the same exposure conditions, and when transferred, it can be transferred with exactly the same image exposure amount as one year ago, and blocking when peeling off the protective film of the image forming material Did not happen at all. This means that all of the reactive components in the photosensitive layer remained unchanged for 1 year under the condition of storage at 40 ° C.

Comparative Example 1 In place of the yellow isoindoline pigment blended in the photosensitive layer in Example 1, a disazo pigment Permanent Yellow GRX (manufactured by Hoechst Japan Co., Ltd.) was used. An image-forming material was prepared in the same manner as in 1. above, imagewise exposure was carried out, and the protective film was peeled off. As a result, a part of the photosensitive layer was blocked by the protective film. The image exposure sensitivity after storage for 1 year required 3000 mj / cm ² .

Comparative Example 2 In place of the yellow isoindoline pigment compounded in the photosensitive layer in Example 1, a disazo pigment, Lyonol Yellow 1919 (manufactured by Toyo Ink Mfg. Co., Ltd.) was used. An image-forming material was prepared in the same manner as in Example 1, imagewise-exposed, and the protective film was peeled off. As a result, a part of the photosensitive layer was blocked by the protective film.

[0017]

According to the present invention, the solid density, color value, material storability, image resolving power, transparency, trapping, etc., which are the same as those of the prepress proof using the conventional azo pigment, and transfer are achieved. An image forming material that does not cause blocking sometimes is obtained.

Claims (1)

[Claims] 1. An image is obtained by having a transferable colored photocrosslinkable resin layer on a support, rendering only an exposed portion non-transferable by image exposure, and transferring the unexposed portion to an image receptor. An image forming material, which is a material for forming, wherein the colorant contained in the photocrosslinkable resin layer is an isoindoline pigment.