JPS6173156A - Water-free lithographic plate - Google Patents

Abstract

PURPOSE:To form a printing plate having higher ink repellency by using a silicone rubber layer obtained by addition reaction between a H-Si compd. and unsatd. bonds. CONSTITUTION:The silicone rubber layer is obtained by the addition reaction between a compd. having >=2 H-Si bonds in one molecule and a compd. having >=2 C=C bonds in one molecule. This rubber layer is used for the ink repelling layer, and when it is thin, problems, such as deterioration in ink repellency and easy scratchability, occur, and when it is thick, developability is deteriorated. Therefore, it is desirable to have a thickness or 0.5-50mum. The silicone rubber layer is formed by the addition reaction between the Si-H and C=C bonds and hardening, and it has a small amt. of silanol groups in the rubber as compared with the one obtained by the condensation reaction, and it is superior in ink repellency.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a waterless lithographic printing original plate, and in particular, to a waterless lithographic printing original plate with excellent ink repulsion properties, in which a substrate, a photosensitive layer, and a silicone rubber layer are sequentially laminated. Concerning master plates for lithographic printing.

[Conventional technology]

Various types of waterless lithographic printing plates using silicone rubber as an ink repellent layer have been known in the past, but in particular, Japanese Patent Publication No. 54 269
As proposed in No. 23, a printing plate formed by laminating a substrate, a photosensitive layer, and a silicone rubber layer in this order has excellent image reproducibility and printing durability.

It has been put into practical use.

The following compositions and curing methods for silicone rubber layers have been proposed so far.

(1) A method of crosslinking an organopolysiloxane having hydroxyl groups at both terminals with a silane or siloxane having a hydrolyzable functional group directly bonded to a silicon atom to form a silicone rubber (hereinafter referred to as condensation type) (hereinafter referred to as a condensation type). Examples of the group include an acetoxy group, a ketoximate group, an alkoxy group, and hydrogen).

(2) A method of crosslinking organopolysiloxane with a radical initiator such as peroxide to form silicone rubber (hereinafter referred to as radical crosslinking type).

etc.

[Problem that the invention seeks to solve]

The method proposed here causes several problems in printing plate performance. The net stand type has high adhesion to the photosensitive layer and offers excellent printing durability, but
Depending on the amount of moisture in the atmosphere when the silicone rubber layer is cured, the adhesion strength with the photosensitive layer fluctuates, and therefore the exposure sensitivity tends to fluctuate. Also, due to the unreacted silanol groups in the cured silicone rubber layer, the ink There is a problem in that the repulsion is not fully satisfactory. The silicone rubber layer is obtained by curing by radical crosslinking.

Because the adhesive strength with the photosensitive layer is extremely low, printing durability is extremely poor, making it impractical, and crosslinking is easily inhibited by oxygen during curing, resulting in high temperatures.

There is a problem in that it is necessary to set curing conditions for a long time.

As described above, with the conventionally proposed methods of curing silicone rubber layers, it has not been possible to obtain a material that maintains stable adhesive strength and has high ink repellency.

The purpose of the present invention is to develop a waterless lithographic printing original plate that has high ink repulsion and one-plate performance that is not affected by the atmosphere during curing of IJ cone rubber. .

[Means to solve the problem] The present invention relates to a substrate and a photosensitive layer provided on the substrate.

and a waterless planographic original plate comprising a silicone rubber layer provided on the photosensitive layer, the silicone rubber layer being one
A waterless lithographic printing original plate comprising an addition reaction product of a compound having two or more hydrogen-silicon bonds in a molecule and a compound having two or more carbon-carbon unsaturated bonds in one molecule. Regarding.

In the laminate formed by laminating the substrate, the photosensitive layer, and the silicone rubber layer in this order in the present invention, the characteristics of the photosensitive layer change due to exposure to light, resulting in a change in the adhesive strength between the silicone rubber layer and the photosensitive layer, or a change in the adhesive strength of the photosensitive layer. Causes a change in solubility in developer. Therefore, by utilizing the difference in adhesive strength or the difference in solubility between the exposed area and the unexposed area, the silicone rubber layer can be divided into areas where it is removed and areas where it remains by development. The photosensitive layer or substrate is exposed in the area where the silicone rubber layer is removed, and is ink receptive, forming nine image areas. The part where the silicone rubber layer remains is ink repellent,
It forms a non-image area and becomes a waterless lithographic printing plate.

In the present invention, substrates include metals such as aluminum and steel, plastics such as polyester and polyamide,
Rubber, coated paper, or a composite material thereof is used. Further, it is optional to provide a coating layer between the substrate and the photosensitive layer in order to improve adhesive strength or prevent halation.

The thickness of the photosensitive layer in the present invention is arbitrary.

Preferably, the thickness is between 0.05 and 100 microns. As for the type of photosensitive layer.

(1) A monomer having a photopolymerizable unsaturated bond.

Those containing oligomers (21) Those containing compounds that have a functional group that can be dimerized by exposure to light (3) Those containing compounds that have a diazo group as a photosensitive group (4) The compounds that have an azide group as a photosensitive group In particular, it is desirable to contain an ethylenically unsaturated bond or an organic hydroxyl group in the photosensitive layer in order to stabilize the adhesive force with the silicone rubber layer.

The silicone rubber layer in the present invention serves as an ink repellent layer, and if the thickness is small, there will be problems such as a decrease in ink repellency and the possibility of scratches, while if the thickness is large, the developability will be poor. from.

The thickness is preferably from 0.5 microns to 50 microns.

Formation of the silicone rubber layer in the present invention.

-5iH and carbon-carbon unsaturated bonds, and the resulting silicone rubber has fewer silanol groups in the rubber than those obtained by molding, and has better ink repellency. It has the feature of being excellent in. Here, the carbon-carbon unsaturated bond group is a substituted or unsubstituted alkenyl group having 2 to 10 carbon atoms.

Examples include alkenylene 7 groups, alkynyl groups, and alkynylene groups, and aromatic carbon-wet carbon unsaturated bonds are not included.

The silicone rubber of the present invention can also be obtained, preferably, by the reaction of a polyvalent hydrogen organopolysiloxane with a non-siloxane compound having two or more carbon-carbon unsaturated bonds in one molecule.

(a) 100 parts by weight of an organopolysiloxane having at least two alkenyl groups (more preferably vinyl groups) directly bonded to silicon atoms in one molecule (b) Organopolysiloxane having at least two Si-H bonds in one molecule Hydrodiene polysiloxane 0.1~io
, ooo parts by weight (O) Addition catalyst 0.00001 to 1 part by weight is cured. The alkenyl group of component (a) may be located at the end or in the middle of the molecular chain,
Organic groups other than alkenyl groups include substituted or unsubstituted alkyl groups and aryl groups. Optionally, the component (-) may have a trace amount of hydroxyl group. Component (b) reacts with component (=) to form a silicone rubber, and also serves to provide adhesion to the photosensitive layer. Component (b)
The hydrogen group is at the end of the molecular chain.

It may exist anywhere in between, and organic groups other than hydrogen are selected from the same groups as those for component (a). It is preferable that 60% or more of the organic groups in component Gl) and component (b) be methyl groups in general, from the viewpoint of improving ink repellency. The molecular structures of component (a) and component (b) are linear.

It may be either cyclic or branched, and at least one of them has a molecular weight of 1. It is preferable from the viewpoint of rubber physical properties that the molecular weight exceeds OOO, and it is further preferable that the molecular weight of component (a) exceeds 1.000.

As the component (-), α,ω-divinylpolydimethylsiloxane, (methylvinylsiloxane/
)(dimethylsiloxane) copolymers, etc., and component (b) includes polydimethylsiloxane having a hydrogen group at both ends, α,ω-dimethylpolysiloxane, and (methylsiloxane) having a methyl group at both ends. Examples include copolymers and cyclic polymethylsiloxanes.

The addition catalyst of component (C) may be arbitrarily selected from known ones, but platinum-based compounds are particularly preferred.

Examples include simple platinum, platinum chloride, chloroplatinic acid, and olefin-coordinated platinum. For the purpose of controlling the curing rate of these compositions, it is also possible to add crosslinking inhibitors such as organopolysiloxanes containing vinyl groups, such as tetrancro(methylvinyl)siloxane, and alcohols containing carbon-carbon 31 bonds. be.

These compositions undergo an addition reaction and begin to cure when the six components are mixed, but the curing rate is characterized by rapidly increasing as the reaction temperature increases. Therefore, in order to lengthen the pot life of the composition until it becomes a rubber and to shorten the curing time on the photosensitive layer, the curing conditions for the two compositions were set at a temperature within a range that did not change the characteristics of the substrate and photosensitive layer. ,
In addition, it is preferable to maintain the temperature at a high temperature until it is completely cured in order to maintain the stability of the adhesive force with the photosensitive layer.

In addition to these compositions, known adhesion promoters such as alkenyltrialkoxysilanes may be added, or organopolysiloxanes containing hydroxyl groups, which are compositions of condensed silicone rubber, silanes containing hydrolyzable functional groups (or siloxanes) may be added. ) may be optionally added, and a known filler such as silica may also optionally be added for the purpose of improving rubber strength.

In the waterless lithographic printing master plate described herein, it is optional to further coat various silicone rubber layers on the silicone rubber layer having the characteristics of the present invention, and also to coat the silicone rubber layer between the photosensitive layer and the silicone rubber layer. It is also optional to provide an adhesive layer between the photosensitive layer and the silicone rubber layer for the purpose of increasing adhesive strength or preventing poisoning of the catalyst in the silicone rubber composition. In order to protect the surface of the silicone rubber layer, a transparent film laminate or a polymer coating may be applied on the silicone rubber layer.

The printing original plate obtained in this way can be exposed and developed by a known method, and when developed, the silicone rubber layer peels off from the non-image area where the silicone rubber layer remains and the photosensitive layer or substrate is removed. A printing plate with exposed image areas is obtained.

〔Example〕

Examples will be described below. The number of copies in the text 9 indicates parts by weight.

Example 1 60 parts (2) of ethyl acrylate/methyl methacrylate copolymer (copolymerization ratio 70150) were placed on an aluminum substrate processed with a grain chamber having a thickness of 0.3 mm (1)
4 of glycidyl methacrylate and xylylene diamine
An ethyl cellosolve solution of a composition consisting of 1 mole of Morph addition reaction product (3) and 5 parts by weight of Michler's ketone was applied and dried at 50°O to form a 9-polymerizable photosensitive layer (thickness: 5 microns). layer on top.

(4) α,ω-Divinylpolydimethylsiloxane (
Number average molecular weight approximately 12,000) 100 parts (5)
n of a composition consisting of 3 parts of α,ω-dimethylpolymethyl/-1 hydrodiene siloxane (number average degree of polymerization 10) (6) 0-1 part of chloroplatinic acid
-A hebutane solution was applied and heated at 180° C. and 10% Rfi for 5 minutes, dried and cured, and a silicone/rubber layer was provided (thickness: 3 miccon).

The laminate prepared as described above was laminated with a polypropylene film 1 Trefan # (manufactured by Toshi Co., Ltd.) having a thickness of 10 microns using a calendar roller, thereby forming a printing original plate.

A positive film was closely attached to this printing original plate, and exposed for 3 seconds from a distance of 1 m using a 3 kW high-pressure mercury lamp (manufactured by Oak Seisakusho). “When I peeled off Tre 7 Anne 1 and developed it with n-hebutane using Dynic's ``Sofbat'', the silicone rubber layer remained in the exposed areas, and the silicone rubber layer peeled off in the non-exposed areas, making it susceptible to polymerization. A printing plate with exposed layers was obtained.

This printing plate was set in an offset printing machine and printed without adding dampening water using Dainippon Ink's lithographic ink "Apex G" red.

A printing plate was obtained which had excellent image reproducibility and was free from scumming due to ink adhesion to non-image areas.

The silicone rubber was then cured at 100° C. and 80% R[, and exposed, developed and printed in the same manner as above to obtain printed matter with excellent image reproducibility.

Comparative Example Example 1 ↓ Check the composition of the silicone rubber layer)
μ, ω-dihydroxypolydimethylcloxane (number average molecular weight approximately 12,000) IClil portion (2)
Ethyltriacetoxysila 7 5 parts (3) Dibutyltin diacetate 0.5 parts, 10%
Curing was performed under conditions of RH and 80% RH, and "Torefa Z" was laminated to obtain two types of printing original plates.

The printing original plate obtained under the former curing conditions was exposed and developed in the same manner as in Example 1 to obtain a printing plate.

When printing was carried out under the same ink density and temperature conditions as in Example 1, a printed matter with background smudges where the ink adhered to the non-image areas was obtained.

Also, the original printing plate obtained under the latter curing conditions.

When exposure and development were performed in the same manner as in Example 1,
The sensitivity decreased and the silicone rubber layer forming the non-image area partially peeled off, resulting in a plate unsuitable for use as a printing plate.

Example 2 γ-cinnamoyl 7-β-hydroxy-n-propyl lacquer 1 was deposited on a 0.5-thick aluminum plate processed with a grain chamber.
Toluene of root polymer (number average molecular weight 4,000),
A photodimerizable photosensitive layer was provided by coating a solution of methyl isobutyl ketone (1 part by weight). On the photodimerizable photosensitive layer, a silicone rubber layer similar to that in Example 1 and 'Trephay' were sequentially laminated to obtain a printing original plate.

When the obtained printing original plate was exposed and developed in the same manner as in Example 1, the silicone rubber layer remained in the exposed areas, and the silicone rubber was peeled off in the non-exposed areas, exposing the photodimerizable photosensitive layer. I got the printed version.

When this printing plate was used for printing in the same manner as in Example 1, printed matter with no scumming and excellent image reproducibility was obtained.

Example 3 A phenol formaldehyde resol resin "Sumilite Resin PC-1" manufactured by Sumitomo Thuleres was applied onto a grained aluminum plate having a thickness of 0.2 mm.

° It was cured for 3 minutes at 200°C. (1 micron thick).

Using this laminate as a substrate, a partially sulfonic acid ester product (esterification rate A 42%) tetrahydrofuran solution was applied and dried to provide a 2 micron thick photosensitive layer. Subsequently, a silicone rubber layer and a "Tray 7" layer were provided on the photosensitive layer in the same manner as in Example 1 to obtain a printing original plate.

Iwasaki Electric's metal halide lamp "Idol Fin 2"
000'', the entire surface was exposed for 6 seconds at an illuminance of 11 mw/i using an AY meter (Oak Seisakusho Light Measure Type UV402A).

A negative film was closely adhered to the printing original plate which had been entirely exposed as described above, and imagewise exposed for 60 seconds at an illuminance of 11 m x 7 m''.

Next, "TOREFAN" is peeled off and pre-treatment liquid (molecular weight 4
00 (100 parts of polypropylene glycol, 0.5 parts of monoethanolamine) for 1 minute, and then immersed in a developer (water) using a nylon brush.

Developed with ethanol, 90/10] i amount ratio).

Peel off the silicone rubber layer and photosensitive layer from the exposed area.

A printing plate was obtained in which an image area was formed in which the substrate was exposed, and a non-image area in which the silicone rubber layer remained was formed in the non-exposed area.

When the obtained printing plate was used for printing in the same manner as in Example 1, a printed matter with excellent image reproducibility was obtained.

Example 4 "Sumilite Resin PC-1" was coated on a grained aluminum plate having a thickness of 0.2 all in the same manner as in Example 3.

Use this laminate as a substrate.

(1) Photosensitive layer composition of Example B 100 parts + 21 parts
A tetrahydrofuran solution of a composition consisting of 20 parts of 4,4/-diphenylmethane diisocyanate (3) and 0.1 part of dibutyltinsilaurylate was applied and heated at 110°C.
, dried and cured for 1 minute to provide a 2 micron thick photosensitive layer.

Next, a silicone rubber layer and a 1 trepan" silicone rubber layer were sequentially laminated on the photosensitive layer in the same manner as in Example 1 to obtain a printing original plate.

A negative film is attached to the resulting printing plate.

Exposure was carried out for 60 seconds using the same exposure machine and illumination intensity as in Example 3.

Peel off the "Trephan" and use a developer (n-hexane, ethyl alcohol) using "Sofunokurad".

40,760 weight ratio), the exposed area forms an image area where the silicone rubber layer peels off and the photosensitive layer is exposed, and the non-exposed area forms a non-image area where the silicone rubber layer remains. I got it.

When the obtained printing plate was printed in the same manner as in Example 1, a printed matter with excellent image reproducibility was obtained.

〔Effect of the invention〕

In a waterless lithographic original plate composed of a substrate, a photosensitive layer, and a silicone rubber layer laminated in this order, compared to the conventionally proposed silicone rubber layer obtained by curing by condensation, the present invention's Notsuta Hydrodiene silicon compound,
The silicone rubber layer obtained by addition reaction with unsaturated bonds provides a printing plate with higher ink repellency.

Claims (1)

[Claims] In a waterless planographic original plate consisting of a substrate, a photosensitive layer provided on the substrate, and a silicone rubber layer provided on the photosensitive layer, the silicone rubber layer has two or more hydrogen-silicon bonds in one molecule. 1. A waterless lithographic printing original plate comprising an addition reaction product of a compound having the following: and a compound having two or more carbon-carbon unsaturated bonds in one molecule.