JPH01238935A - Manufacture of lithography printing plate - Google Patents

Abstract

PURPOSE:To compose a direct offset printing plate from the digital data of a computer by providing resin not dissolved in water on a board, superposing a plate sheet graft-polymerized with hydrophilic monomer on the surface of the resin and a transfer sheet provided with a transfer layer containing hydrophobic thermoplastic resin on the board thereby, heating it and transferring the layer partly onto the plate sheet. CONSTITUTION:Sheet, a metal plate, a plastic sheet, etc., may be used as a board. As resin not dissolved in wafer, epoxy resin is preferably employed, and as hydrophilic monomer, acrylamide is preferably employed. A grafting method is conducted by applying energy such as heat, light, electron beam or the like. As hydrophobic thermoplastic resin, epoxy resin, polyester resin, etc., are employed solely or in combination. In order to form an image of a transfer layer on a plate sheet, the plate sheet and a transfer sheet are superposed with the board at the outside, heated in an image state from the side of the transfer sheet, thereby partly transferring the transfer layer onto the plate sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a lithographic printing plate that can be made in a heat mode, and particularly to a so-called direct plate-making material that can be made directly from a computer.

[Conventional Technique 4@] Conventional systems for direct plate making from computer digital data A include (a) a combination of laser scanning exposure and electrophotography, and (b) scanning using a high-power laser such as Co1. Those that change the resin layer etc. by coating, (1) Laminated photosensitive resin and silver salt sensitive material,
There are those that perform scanning exposure using an Ar laser, and (1) a silver master type that uses a semiconductor device or HeNe laser for exposure.

In method (a), since electrophotography is used, at least the steps of charging, exposure, and development are required, making the apparatus complicated and large-scale. In addition, the dry development method has poor image quality and is unsuitable for printing, while the wet development method is unfavorable due to occupational health and safety concerns.Furthermore, the method of using the toner image as a resist and removing the non-image area is even more difficult than the wet development method. This is not preferable because the number increases by about 1.

In the method (a), the high-output laser itself, such as a CO, YAG laser, is large-scale, resulting in a huge device and large energy consumption. Furthermore, the reliability of these lasers, such as their lifespan, was not sufficient.

In method (1), a silver salt sensitive material is exposed to an Ar laser, the exposed areas are blackened by wet development, the entire surface is irradiated with UV, and the photosensitive resin layer is developed by wet development. However, not only was the process complicated, but the cost of the plate material was also high.

Method (1) has the drawbacks of high cost due to the use of silver salt and wet development.

On the other hand, a transfer sheet using a heat-sensitive melt transfer method, in which a transfer layer made of wax, pigment, etc. is provided on a thin substrate,
This is a method in which transfer objects such as paper are placed one on top of the other, and the transfer sheet is heated from the transfer sheet side in an imagewise manner using a thermal head, etc., to partially transfer the transfer layer to the transfer object.This method can be processed dryly, and the process It is widely used in printers because it is simple, the device is small, and it requires no maintenance. In addition, there has been remarkable progress in increasing the density of thermal heads.
It is reaching a level where it can also be used as a printed version. However, simply transferring an image onto a hydrophilic substrate using a heat-sensitive melt transfer method does not result in a lithographic printing plate.The current transfer layer uses wax as a binder, which is insufficient for printing and has poor printing durability. This is because there are almost no In addition, transfer layers using polyester resin or acrylic resin as a binder have already been announced, and although they have sufficient strength, they lack meltability, and if the transferred object is not smooth, they will be difficult to obtain. An image cannot be obtained, but at present, there is no substrate that is highly smooth and highly hydrophilic.

[Object of the Invention] In order to eliminate the above-mentioned drawbacks, the present inventors have focused on the lithographic printing plate production method and the layer structure, and as a result of extensive research, they have arrived at the present invention.

An object of the present invention is to provide a method for making an offset printing plate directly from digital data of a computer using a compact device and a dry process.

[Summary of the invention] A transfer system in which a water-insoluble resin is provided on a substrate, a plate sheet is graft-polymerized with a hydrophilic monomer on the surface thereof, and a transfer layer containing a non-hydrophilic thermoplastic resin is provided on the substrate. This is a lithographic printing plate manufacturing method characterized by stacking sheets with the substrate facing outside, heating them image-wise from the transfer sheet side, and partially transferring the transfer layer onto the plate sheet.

[If a water-insoluble resin is placed on the working substrate and a water-based monomer is grafted onto its surface, properties such as strength and smoothness will remain as the water-insoluble resin, and only strong hydrophilic properties will be obtained.] applied to the surface. Furthermore, since it is a chemical bond rather than a simple lamination, it will not peel off during printing, and the hydrophilicity is not due to the unevenness of the surface, but due to the hydrophilic groups on the surface, so it has smoothness. Even a transfer layer containing a strong resin, which has high strength but poor meltability, can be transferred without disturbing the image quality. By selecting a non-hydrophilic resin for the transfer layer, a lithographic printing plate can be produced in which ink adheres to transfer areas and does not adhere to non-transfer areas.

[Details of the invention] The present invention will be explained in detail below.

As the substrate, paper, a metal plate such as aluminum, a plastic sheet such as a polyester sheet or polyvinyl chloride, etc. can be used.

As resins that do not dissolve in water, epoxy resins, polyester resins, acrylic resins, polyamide resins, polypeptides, vinyl resins such as vinyl acetate, melamine resins, urethane resins, silicone resins, etc. can be used, but they can be easily grafted and bonded. From the viewpoint of workability due to properties, flexibility, solubility, etc., epoxy resins, polyester resins, acrylic resins, and polyamide resins are preferred singly or in combination. In particular, epoxy resins have a high grafting speed (preferably).

Examples of hydrophilic salts include acrylamide, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, acrylic acid, methacrylic acid, N-vinylpyrrolidone, methacrylamide, methylenebisacrylamide, acrylonitrile, etc. In particular, acrylamide is preferred because of its high hydrophilicity.

The grafting method can be performed by applying energy such as heat, light, electron beam, etc. In particular, grafting by light irradiation is preferable because it can be carried out efficiently using a relatively simple device. methods that excite monomers, and (1) methods that introduce functional groups into the main chain. However, method (a) is preferable because of its ease of material selectivity and high grafting efficiency. for,
The surface of the resin to be grafted is coated with an aqueous or organic solvent solution of hydrophilic 7-mer-1 and a sensitizer such as benzophenone or benzoyl peroxide, irradiated with light such as ultraviolet rays, and washed with water to form a homopolymer. This is done by removing.

There are no particular restrictions on the non-hydrophilic thermoplastic resin as long as it draws ink during printing and softens at a temperature and amount of heat similar to that of a thermal head, but it is preferably one that has good releasability during transfer and good image quality. It is preferable to use epoxy resins, polyester resins, acrylic resins, and vinyl resins selected based on their softening points, either singly or in combination, from the sharpness that has a great effect on the... 11, it is necessary to pay special attention to compatibility, and the glass transition temperature is preferably 50°C to 110°C. Furthermore, polyethylene powder, synthetic or natural wax, etc. are used to improve transferability. It is preferable to contain it.

As the substrate of the transfer sheet, substrates conventionally used for thermal transfer recording can be used. That is, 0.5-20
A film made of polyester resin or the like having a thickness of μm is preferred.

The transfer layer can also contain organic or inorganic pigments or dyes for visualization and sharpness of the image.

In order to form an image of the transfer layer on the printing sheet, the printing sheet and the transfer sheet are both placed one on top of the other with the substrate on the outside.
It is carried out by heating image-wise from the transfer sheet side and partially transferring the transfer layer onto the plate sheet. At this time, the pressure applied to both sheets is preferably 0.1 to 10 kgw/cm. As a heating method, in addition to using a thermal head, it is also possible to use laser scanning or photothermal conversion using a flash.

The formed image can be used as a lithographic printing plate because the transferred portion has ink adhesion properties and the non-transferred portion has strong hydrophilicity.

[Example] Hereinafter, the present invention will be explained in detail with reference to Examples.

(Example 1) The following composition Epicoat 1001 (epoxy resin manufactured by Shell Chemical Co., Ltd.) was applied on a 100 μm polyester film.
95g dodecyldimethylamine 5g 2-butanone
100g of resin solution was coated with a dry film thickness of 5% using a bar coater.
μm was coated and dried and cured at 120° C. for 2 hours.

Further composition Acrylamide 50g Benzophenone 5g Ethanol
25g water
Soaked in 25g solution, 1.5k
The acrylamide homopolymer was removed by rubbing with a sponge under running water, which was then irradiated for 3 minutes from a distance of 5 Qcm using a W ultra-high pressure mercury lamp, and dried to prepare a plate sheet.

Next, the composition carbon black 2gBR-80
(Mitsubishi Rayon methacrylic resin) 1g VAGH (UCCCC salt-and-acetate vinyl copolymer g) Polyethylene powder 2g 2-butanone Grind and disperse 80g of '!I in a paint conditioner for 1 hour to create a transfer i coating liquid, which is then used in advance for stinking on the back side. A transfer sheet was prepared by coating a 6 μm polyester film provided with a preventive layer with a bar coater to a dry film thickness of 4 g/cm.

The resulting transfer sheet and plate sheet were placed one on top of the other with the substrate on the outside, and heated using a thermal simulator (printing conditions: applied power: 0.45 W) so that the transfer sheet was heated from the side.
/dat, pulse width 2.5 m5ecON10FF), and the transfer layer was partially thermally transferred to the plate sheet. As a result, a good image was formed on the plate sheet, and a lithographic printing plate was produced.

When this lithographic printing plate was installed in an offset printing machine AD-80 manufactured by Ryopi Inbetsu Kikai and printed, a printed matter with a good image with ink adhering to the transfer area was obtained. The 1000th image was also as good as the first image.

[Effect of the invention 1 As described above, according to the present invention, by the thermal transfer method,
An offset printing plate can be easily produced directly from digital data by dry processing, and the resulting image quality is good and printing durability is also good.

Claims (4)

[Claims] (1) A printing sheet in which a water-insoluble resin is provided on a substrate and a hydrophilic monomer is graft-polymerized on the surface thereof, and a transfer sheet in which a transfer layer containing a non-hydrophilic thermoplastic resin is provided on the substrate. , a method for producing a lithographic printing plate characterized by stacking both substrates on the outside, heating the transfer sheet in an imagewise manner from the side, and partially transferring the transfer layer onto the plate sheet. (2) The method for producing a lithographic printing plate according to claim 1, wherein the hydrophilic monomer is acrylamide. (3) The method for producing a lithographic printing plate according to claim 1, wherein the water-insoluble resin is one or more resins selected from epoxy resins, polyester resins, acrylic resins, and polyamide resins. (4) The lithographic printing plate according to claim 1, wherein the non-hydrophilic thermoplastic resin is one or more resins selected from epoxy resins, polyester resins, acrylic resins, and vinyl resins. Fabrication method.