JPS6045422B2 - Plate making method for photosensitive planographic material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for making a photosensitive lithographic material without using conventional negative or positive films.

Offset printing plates are usually obtained by providing a hydrophobic image on a hydrophilic support (eg, hydrophilized paper, metal, etc.).

Direct drawing method is used to form images. There are transfer methods, electrophotographic methods, etc., but optical methods are used to reproduce subtle tones from highlights to shadows, and to clearly and faithfully reproduce letters and other patterns. In order to create a printing plate optically, a photosensitive substance is naturally required, and a photosensitive lithographic material called a PS plate is commercially available, in which a photosensitive substance is coated on a suitable support.

When a hydrophobic photosensitive substance coated on a PS plate is exposed to light, it undergoes polymerization, crosslinking, and strengthening of molecular entanglement due to photochemical reactions, resulting in soluble 1, ★, 1'J- in the exposed and unexposed areas.
Six-year-old boss λ! ΔYujou, you can develop the image and create an image.

On the other hand, an image can also be created by a method in which the exposed portion generates a soluble group through a photoreaction, increasing solubility, and removing that portion by dissolving it. Furthermore, images can also be created by causing a difference in adhesiveness between the support and the photosensitive material through a photoreaction, regardless of the difference in solubility. The above-mentioned photosensitive substances that change with light are generally called photopolymers, and are classified as follows, for example, according to "Photosensitive Resins" by Takahiro Tsunoda (Printing Society Publishing Department).

1 Photosensitive resin having a diazo group as a photosensitive group 2 Photosensitive resin having an azide group as a photosensitive group 3 Photosensitive resin having a cinnamoyl group as a photosensitive group (photodimerization type) 4 Photosensitive resin having a (meth)acryloyl group as a photosensitive group Photosensitive resin photopolymers undergo various chemical changes when exposed to light, but among these chemical changes, photosensitive substances whose reactions are initiated by radicals generated by irradiation with active light have a reaction caused by oxygen present in the air. Therefore, reaction inhibition effect (
quenching of radicals).

Therefore, in a PS plate coated with such a photopolymer, if the photosensitive material is directly exposed to air, no photochemical change may occur even if it is irradiated with actinic light. In order to prevent this inhibiting effect caused by oxygen, ordinary PS plates are provided with an oxygen-blocking cover film or an equivalent oxygen permeation-preventing layer.
The present inventors focused on the relationship between the photochemical reaction inhibiting effect of oxygen and the oxygen-blocking film that prevents this, and arrived at the present invention. That is, in the present invention, an image forming layer made of a photosensitive material that is cured by irradiation with actinic light is provided on a base material, a transparent plastic film having an opening pattern is overlaid on the surface of the image forming layer, and actinic light is irradiated through the film. There is a method for making a photosensitive lithographic material, which is characterized in that image formation is performed by eluting and removing uncured portions corresponding to the openings of an opening pattern.

The photosensitive substance that hardens upon irradiation with actinic light refers to a substance that hardens and becomes insolubilized by a radical reaction initiated by irradiation with actinic light.

Specific examples of such substances include photosensitive resins having photodimerization-reactive photosensitive groups such as (meth)acryloyl groups or cinnamoyl groups, and in particular photosensitive resins having (meth)acryloyl groups ((meth) ) not only polymers having an acryloyl group but also photocrosslinkable monomers or monomer adducts having a (meth)acryloyl group) are preferably used. The transparent plastic film used in the present invention is preferably a transparent oxygen-blocking film having a transmittance of 50% or more for light having a wavelength of 300 TIUn or more.

The aperture pattern can be created by various methods. It may be directly drawn on the photosensitive layer with a brush using a plastic solution, or it may be cut out in a pattern from a transparent plastic film and affixed to the printing plate. Conversely, openings may be provided by cutting out a transparent plastic film pasted on the entire surface of the plate. Furthermore, oxygen can pass through even if the transparent plastic film of the printing plate is scratched with an iron pen, etc., and it is also possible to create opening patterns by scratching the transparent plastic film by striking type (direct writing method).
. Alternatively, the opening pattern 3 may be provided on another base material, and the pattern may be transferred to the surface of the PS plate by pressure, heat, etc.
transcription method). Further, the aperture pattern can be provided by electrophotography using a toner capable of forming a transparent film, or the aperture pattern can also be provided by applying heat to the transparent plastic film on the printing plate and blowing it off. A thermosensitive recording method can be used to heat the plastic film, or a laser beam can be used. It is also possible to obtain an aperture pattern using a so-called discharge destruction method. When an aperture pattern is formed on the plate using these methods and the entire plate is exposed to active light, oxygen inhibits photo-insolubilization of the apertures depending on the pattern.
By developing this, a printing plate corresponding to the opening pattern can be obtained.

The method of the present invention is particularly effective for plate making of lithographic printing materials that do not require dampening water.

An example of a lithographic printing material that does not require dampening water is
2304? A silicone rubber layer is provided as an ink-repellent material on the substrate, an ink-receptive photosensitive material layer is provided on this layer, and the non-image areas are removed by developing after pattern exposure and the ink-repellent areas are removed. A silicone rubber layer is exposed or a silicone rubber layer is provided on the photosensitive material, and after pattern exposure, the silicone rubber corresponding to the image area is removed together with the photosensitive layer by development, and the remaining silicone rubber layer is used as an ink-repellent area. A dampening solution-free lithographic material has been proposed which is produced by the following methods.

Furthermore, JP-A-50-5010 has a photopolymerizable adhesive layer containing an ethylenically unsaturated monomer and a photoinitiator on a substrate, and a silicone rubber layer thereon, which is a lithographic printing material that does not require dampening water. is proposed. When plate making of these lithographic printing materials that do not require dampening water is carried out using known methods, they are significantly inhibited by oxygen in the air, and as a result, the necessary reactions such as photoinsolubilization and photoadhesion do not occur sufficiently. There is a problem.

According to the method of the present invention, such problems can be easily solved,
It is possible to clearly reproduce images that are faithful to the original. Example 1 Thickness 5 with the following composition on a grained aluminum plate
A photopolymerizable photosensitive layer of μ was provided.

a Unsaturated polyester 1 polylide MRll3lR. manufactured by Dainippon Ink Chemical Co., Ltd. solid matter (bisphenol A1
Polycondensate of propylene oxide and maleic anhydride)
55 parts by weight b Addition reaction product of 4 moles of glycidyl methacrylate and 1 mole of xylylene diamine
4 parts c Michler's ketone 5 parts by weight Next, a pattern was drawn with a brush using a 3% aqueous solution of polyvinyl alcohol with a Kuhn degree of 90%.

After the pattern was dried, it was irradiated with light from a high-pressure mercury lamp (0RC Jet Light 3000) in the air for 2 minutes from a distance of 90 cm, and developed using isopropyl alcohol. PVA
Only part of the film was cured, and the other parts of the photosensitive layer were dissolved and removed. Offset printing was performed using this plate, and prints that were faithful to the handwriting were obtained. Example 2 A 5 μm thick photopolymerizable photosensitive layer having the following composition was provided on a grained aluminum plate.

a Bayer Polyurethane 1 Inplanil ELNO
5(2)b Addition reaction product of 4 moles of glycidyl methacrylate and 1 mole of xylylene diamine
(4) Part c Mr. Michler's ketone
1 part d carbon black 1
Next, a polypropylene film 1 Toray Juan J (thickness: 5 μm) manufactured by Toray Industries, Inc. was laminated thereon.

The aluminum substrate of this printing original plate was grounded, and a plane scanning discharge recording was performed using a pin electrode to obtain an aperture pattern.
This was exposed in the air in the same manner as in Example 1, and after peeling off the polypropylene film, it was developed with isopropyl alcohol to obtain a lithographic printing original plate. Example 3 A photopolymerizable photosensitive layer having the following composition was spin-coated onto a brush-polished aluminum plate to a thickness of 6p.

a Styrene, ethyl acrylate, acrylic acid (20/
70/10) Copolymer ω part b Diethylene glycol diacrylate Shun part c Benzoin ethyl ether 3 parts Next, using a spray gun, spray a 90% saponified polyvinyl alcohol aqueous solution with a viscosity of 10 Cy, pS onto the plate surface to form an opening pattern. has been established.

This was exposed and developed in the same manner as in Example 1 in the air to obtain a lithographic printing original plate. Example 4 A 10% acetone solution of the following polydiorganosiloxane and a product obtained by reacting the hydroxyl groups contained therein with acroyl chloride was spin-coated onto a grained aluminum plate, and after drying, it was coated with a Toray Co., Ltd. product. A 9 micron film of polypropylene film was laminated onto the silicone surface.

This cover film was cut out in a pattern and exposed to low pressure mercury lamps (20W x 8 lights, 5cm distance) in the air.
After peeling off the cover film, it was developed with alcohol to obtain a lithographic printing plate that did not require dampening water. Example 5 A photopolymerizable photosensitive layer having a thickness of 9 μm and having the following composition was provided on a brush-polished aluminum plate.

a Methyl methacrylate, ethyl acrylate, acrylic acid (35/60/5) copolymer (branch) part b Addition reaction product of 4 moles of glycidyl methacrylate and 1 mole of xylylene diamine ♀ part c Michler's ketone
5 parts RTV Silicone Gum Dispersion R manufactured by Toshiba Silicone was applied on this photopolymerizable photosensitive layer.
YE-3085 was diluted with n-heptane and applied, and air-dried to form a silicone rubber layer with a thickness of 4 μm. On the surface of this silicone rubber layer, a 6 μm thick polyester film 1 Lumirayo manufactured by Toray Industries, Inc. was laminated to obtain a photosensitive lithographic printing original plate. This cover film is cut out in a pattern, exposed in the air in the same manner as in Example 1, and after peeling off the cover film, it is immersed in n-heptane to swell the silicone rubber at the openings, and rubbed lightly with gauze. Only the silicone rubber at the opening was removed. In this way, an image corresponding to the aperture a pattern was reproduced (the photopolymerizable photosensitive layer is exposed in the silicone rubber removed area and becomes ink receptive, but the other areas are ink repellent). When the plate thus obtained was subjected to offset printing without using dampening water, an extremely good printed plate was obtained. Example 6 A sheet with an aperture pattern obtained by peeling off the cover film of the lithographic printing original plate that does not require dampening water and making the plate using the Riso Zenofax system manufactured by Riso Kagaku Kogyo Co., Ltd. was laminated onto a silicone rubber surface, exposed in air as in Example 1, peeled off the sheet, and developed as in Example 5 to obtain a lithographic printing plate that did not require dampening water.

Claims (1)

[Claims] 1. An image forming layer made of a photosensitive material that hardens when irradiated with actinic light is provided on a base material, a transparent plastic film having an opening pattern is placed on the surface of the image forming layer, and actinic light is irradiated through the film. . A method for making a plate for a photosensitive lithographic material, which comprises forming an image by eluting and removing uncured portions corresponding to the openings of the opening pattern. 2. The plate-making method according to claim 1, wherein the photosensitive substance is a photosensitive resin having a (meth)acryloyl group.