JPH03197192A - Offset printing plate for laser plate making - Google Patents

Abstract

PURPOSE:To directly and simply obtain an offset printing plate from the printing data accumulated in a computer or the data or original sheet read by a scanner by providing an image recording layer on a substrate having a hydrophilic surface and forming the same from a layer based on a laser beam absorbing dye, a thermoplastic resin and a compound selected from fatty acid and its derivative. CONSTITUTION:An offset printing plate for laser plate making is formed by providing an image forming layer on a substrate having a hydrophilic surface and the image forming layer is composed of a layer based on a laser beam absorbing dye, a thermoplastic resin and a compound selected from fatty acid and its derivative. The image forming layer is irradiated with laser beam corresponding to data such as computer data or manuscript data and the laser beam absorbing dye contained in the image forming layer absorbs the energy of laser beam to generate heat and the thermoplastic resin is melted by said heat and a hole is formed on the substrate to expose the hydrophilic surface of the substrate. The difference of the wetting to water between an image formed part and an unexposed part and the difference of a contact angle therebetween are largely generated and a highly detailed offset printing plate is obtained.

Description

[Detailed description of the invention] 〔Technical field〕 The present invention relates to an offset printing original plate for laser platemaking.

[Prior art]

Printing methods can be roughly divided into intaglio and lithography (offset).
and letterpress (including gravure) are known and used, but offset printing has recently been growing in the printing field because it is easy to make plates and print, and the equipment is cheaper than other methods. are doing. In particular, offset printing is most effective in office printing.

Offset printing plates are made using an AQ plate coated with a photosensitizer,
A screen is brought into close contact with a plate material such as a Zn plate, an image is irradiated thereon, and then development and hydrophilic treatment are performed.An electrophotographic photoreceptor is used as the plate material, and after charging, exposure, and development, hydrophilic treatment is performed. A method of applying chemical treatment has been adopted.

However, with this conventional offset plate-making method, it is not possible to directly create an offset printing plate from print information stored in a computer, information read by a scanner, or an original plate.

〔the purpose〕

The present invention can be used to print information stored in a computer or the like,
The object of the present invention is to provide an offset printing original plate for laser plate making, which can be easily obtained directly from information read by a scanner, an original plate, etc.

〔composition〕

In the present invention, an image forming layer is provided on a substrate having at least a hydrophilic surface, and the image forming layer comprises (a) a dye that absorbs laser light, (b) a thermoplastic resin, and (C) a dye that absorbs laser light; The present invention relates to an offset printing plate for laser platemaking, characterized in that the layer is mainly composed of at least one compound selected from the group consisting of fatty acids and derivatives thereof.

In the present invention, the term "substrate whose surface is at least hydrophilic" refers to a substrate that is originally hydrophilic or a substrate that is not hydrophilic in itself, but whose surface has been treated to make the surface hydrophilic.

Specific examples of these include a metal substrate, a substrate having a metal layer, and a plastic substrate treated to make it hydrophilic.

The present invention is capable of forming an image by irradiating a laser beam according to information such as computer information or document information, so that a laser light absorbing dye contained in the image forming layer absorbs laser light energy and generates heat. The thermoplastic resin in the layer is melted, holes (pits) are formed on the substrate, and the hydrophilic substrate surface is exposed, and the difference in wettability with water between the image-formed area and the unexposed area. This is based on the discovery that a large difference in contact angle occurs and that an extremely high-definition offset printing plate can be directly obtained.

The present invention will be explained in more detail below.

The metal substrate or the substrate having a metal thin film constituting the offset printing original plate for laser platemaking of the present invention is stainless steel,
AQ, Cr, Ge, ITO (Tin-doped In, 0.), ZnO, Ni, Nichrome, pt.

A metal plate such as Ti or Si, or a plastic film such as polyester film or polyethylene film, in which the metal is deposited in a thin film form by vapor deposition, sputtering, lamination, etc., can be used, and the surface is further treated with 02 plasma to make it hydrophilic. Polyester film, polypropylene film, nylon film, vinyl chloride film, vinylidene chloride film, etc. can be used.

Basically, the static contact angle (θ) with water is small (θ〈6
(preferably 0°), as long as it is hydrophilic.

As a laser, carbon dioxide laser (oscillation wavelength 10.6μ
m), Yztrium Aluminum Garnet (WA
G) L/- laser (oscillation wavelength 1.06μm), copper vapor laser (oscillation wavelength 0.51μm), dye laser, excimer laser (oscillation wavelength 0.351μm when using XeF, XeC
The oscillation wavelength is 0.308 μm for Ω, 0.248 μm for rF, and 0.248 μm for ArF.
193 μm), but in the present invention, infrared light type is particularly preferred.

The dye that absorbs laser light is not particularly limited as long as it can effectively absorb the wavelength used.

Examples of infrared absorbing dyes include cyanine dyes, squalirium dyes, methine dyes, naphthoquinone dyes, quinoneimine dyes, quinonediimine dyes,
Phthalocyanine dyes, naphthalocyanine dyes, dithiol metal complex dyes, anthraquinone dyes, azo dyes.

There are trisazo dyes, pyrylium salt dyes, aminium base dyes, etc., and cyanine dyes, phthalocyanine dyes, naphthalocyanine dyes, and dithiol metal complex dyes have large molecular extinction coefficients and are particularly effective.

Some representative examples of this infrared absorbing dye are shown below (Compound H
a1 to Nα13).

Thermoplastic resins include fluorine thread resin, silicone resin, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer,
vinyl chloride-vinyl acetate-vinyl alcohol copolymer,
Vinyl chloride-vinyl acetate-maleic acid copolymer, vinyl chloride-acrylate copolymer, polyvinylidene chloride, vinylidene chloride-acrylonitrile copolymer, polyester, polyamide, polyacrylate, polymethacrylate, polycarbonate, polyurethane, polystyrene, etc. It will be done.

In particular, a homopolymer or copolymer having an acrylic monomer unit represented by the following general formula is preferred.

1-4CH2-C+ COO-(C1,)tn-(CF, )n-CF,
R.

R1=H,'CH.

R,=H,F m =1.2 n =1 to 7 This type of homopolymer or copolymer can be obtained by polymerizing each constituent monomer according to a conventional method.

Synthesis example CH.

Synthesis of +CH2can Coo (C
H2)z (CF2), CF.

1)1. IFI, 2H,2H-heptadecafluorodecyl methacrylate CH2=C(C1(,)COO(C
)1. ), (CF, )F 50 g (0,094
mol), 0.15 g of azobisisobutyronitrile in 1
．． 1. Add to 50 g of 1-trichloroethane and add 70 to 8
After stirring at 0°C for 5 hours, a viscous precipitate was obtained.

The precipitate was separated in a furnace and washed with 100 mQ of methanol, and the obtained precipitate was crushed in a mortar and washed again with 100 mQ of methanol to obtain the desired product. When the melting point was measured by DSC, it was 75.6°C.

The fatty acids or derivatives thereof used in the present invention include:
Saturated or unsaturated mono- or dicarboxylic acids or their esters, amides, anilides, hydrazides, ureides, anhydrides or fatty acid salts such as ammonium salts or metal salts, etc. Esters include compounds with two or more hydroxyl groups. esters, such as mono-, di- or triglycerides, which also contain halogens,
These saturated or unsaturated fatty acids, which may be substituted with hydroxy groups, acyl groups, acyloxy groups, or substituted or unsubstituted aryl groups, may be straight chain or branched, and unsaturated fatty acids may have double bonds. Alternatively, it may have one triple bond, or it may have two or more triple bonds. The carbon number of these saturated or unsaturated fatty acids is 10
It is preferable that it is above.

Specific examples of saturated fatty acids include undecanoic acid,
Lauric acid, myristic acid, pentadecanoic acid, valmitic acid, heptadecanoic acid, stearic acid, nanodecanoic acid,
Arachic acid, behenic acid, lignoceric acid, cerotic acid,
Examples of unsaturated fatty acids include montanic acid and melisic acid, and examples of unsaturated fatty acids include oleic acid, elaidic acid, linoleic acid, sorbic acid, and stearolic acid. Specific examples of esters include methyl esters, ethyl esters, hexyl esters, octyl esters, decyl esters, dodecyl esters, tetradecyl esters, stearyl esters, eicosyl esters, and tocosyl esters of these fatty acids.

Examples of metal salts include metal salts of these fatty acids such as sodium, potassium, magnesium, calcium, nickel, cobalt, zinc, cadmium, and aluminum.

The fatty acid or fatty acid derivative used preferably has a melting point in the range of 50 to 200°C, particularly 60 to 150°C. The image forming layer of the present invention contains one or two of these fatty acids or derivatives thereof. A mixture of the above can be used.

〔Example〕

49 parts by weight of behenic acid (NAA 222S; manufactured by NOF Corporation) was dissolved in tetrahydrofuran, and this was applied with a blade onto a 75 μm thick polyethylene film on which aluminum had been deposited to form an image forming layer with a film thickness of approximately 5 μm after drying. Established.

When the prepared sample was irradiated with a semiconductor laser beam having an oscillation wavelength of 780 nm and a beam diameter of 3 μm and an irradiation light intensity of 10++V, a pit with a very clear outline was formed, and the aluminum portion was exposed.

When the printing plate thus prepared was subjected to offset printing according to a conventional method, it showed good suitability for printing.

Claims (1)

[Claims] 1. An image forming layer is provided on a substrate whose surface is at least hydrophilic, and the image forming layer comprises (a) a dye that absorbs laser light, (b) a thermoplastic resin, and (c) a fatty acid and An offset printing plate for laser platemaking, characterized in that the layer is mainly composed of at least one compound selected from the group consisting of derivatives thereof.