JPH0545892A - Method for development of photosensitive elastomer composition - Google Patents

Abstract

PURPOSE:To completely dissolve and remove a peeling layer and to improve a problem of orange peeling. CONSTITUTION:A printing plate is manufactured by exposing and a developing a photosensitive resin compsn. structural body to form picture images. The resin structural body consists of a supporting body, diene rubber photosensitive elastomer compsn., and peeling layer. This peeling layer consists of a cellulose deriv. As for a developer, a compd. selected from esters expressed by formula R<1>COOR<2>, dodecylbenzene, and limonin is used indivisually or in a combination with compd. the boiling point of which differs within 20 deg.C from that of the selected ester under normal pressure. In formula, R<1> is CH3 or C2H5, R2 is alkyl group, substd. or unsubstd. cyclohexyl group, alkyl group, or alkoxy polyoxialkylenyl group.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for forming an image from a photosensitive elastomer composition, and more particularly to a developing method using a developer suitable for making a flexographic printing plate.

[0002]

2. Description of the Related Art An image is formed from a photosensitive elastomer composition by exposing it through a transparent image carrier and then developing the unexposed area with a solvent in which the photosensitive elastomer composition is soluble. There is.

As the photosensitive elastomer composition conventionally used for making a flexographic printing plate, (a) a diene polymer, (b) an ethylenically unsaturated compound, and (c) a light are generally used. The thing which has a polymerization initiator as a main component is used. Since these are mainly composed of diene polymers, the unexposed areas cannot be washed out with water or water-based solvents, and chlorine-based organic solvents such as perchlorethylene and 1,1,1-trichloroethane are exclusively used. Was used. In general, a commercially available photosensitive elastomer composition for flexographic printing is formed into a plate shape by extrusion molding or pressing, and has a structure sandwiched between a support and a release layer.

The peeling layer is provided for the purpose of facilitating the adhesion to the transparent image carrier, and it must be dissolved in the developing solution in the developing step in plate making.
When the release layer is a polyamide-based material, n-butanol, for the purpose of enabling dissolution of the film in a developer,
An alcohol-based organic solvent such as isopropanol has been used by being mixed with a chlorine-based organic solvent.

[0005]

Since such a chlorine-based organic solvent has no flammability, it has an advantage from the viewpoint of safety in handling, but on the other hand, it has a problem in hygiene such as being highly toxic to the human body. In addition, the development of a chlorine-free developing solvent has been desired from the viewpoints of improving the working environment and preventing air pollution, such as contributing to ozone layer depletion. Furthermore, in the case of a chlorine-based developing solvent that has been conventionally used, the cured product of the photosensitive elastomer composition that forms the image area swells greatly, and fine lines and dots in the image area may be damaged during the development process. It has a drawback that it takes a long time to recover from the swelling, and improvement is desired also from this point, and a chlorine-free developer has been developed in order to respond to this.

EP 0355578 as a non-chlorine type developer
9, JP-A-62-160446, US484718.
The techniques described in No. 2 and the like can be mentioned as prior arts, but there is no description concerning the release layer.
However, in reality, many photosensitive elastomer compositions for flexographic printing currently on the market use a polyamide-based material as a release layer, and therefore, it is possible to dissolve the release layer when developing these. For this purpose, it was necessary to add and use an alcoholic solvent.

In the conventional chlorine-based developer, the ratio of the chlorine-based solvent and the alcohol-based solvent is large. Therefore, the change in the mixing ratio of the two components after the used solvent is distilled and regenerated is easily adjusted from the specific gravity. Was possible. However, the non-chlorine type developer has a problem that it is difficult to adjust the mixing ratio of the distillation recovery liquid because the two components have similar specific gravities.

[0008]

Means for Solving the Problems The present invention has been studied to solve such problems, and as a result, by using a cellulose derivative as the release layer on the surface of the photosensitive elastomer composition, a specific single organic solvent, Further, it has been found that it is possible to use a developer having a boiling point difference of 20 ° C. or less at normal pressure in combination with it, and the object can be achieved, thereby completing the present invention.

That is, in the present invention, a cellulose derivative is used as a release layer on the surface of a photosensitive elastomer composition and an ester represented by the following general formula (A) or a dodecylbenzene or limonene is selected as a developer. It is intended to provide a plate making method characterized by using a compound alone or in combination with a compound having a boiling point difference of 20 ° C. or less under normal pressure. R ¹ COOR ² ……………… (A) [wherein R ¹ is CH ₃ or C ₂ H ₅ and R ² is —C _n
An alkyl group represented by H _{2n + 1} (n = 6 to 10), -C
₆ H ₁₀ X substituted or unsubstituted cyclohexyl group represented by (X = H, alkyl group having 1 to 4 carbon atoms), -C _n H
_2n · Ar (Ar = an aromatic group, n = 1, 2) aralkyl group represented _{by, - (C n H 2n O} ) a C m H 2m + 1 (n = 2
˜6, m = 1 to 4, a = 1 or 2, a / (na + m)
Represents an alkoxypolyoxyalkylenyl group represented by ≦ 1/4].

The photosensitive elastomer composition suitable for plate making by the developing method of the present invention is preferably composed mainly of (1) diene polymer, (2) ethylenically unsaturated compound, and (3) photopolymerization initiator. It is a component.

As the diene polymer (1), a polymer obtained by homopolymerization of a conjugated diene monomer or copolymerization with a monoolefin compound is used. Examples of the conjugated diene monomer include butadiene, isoprene, chloroprene and the like. Further, as the monoolefin compound used for copolymerization with the conjugated diene monomer, styrene, α-methylstyrene, vinyltoluene, acrylonitrile, acrylic acid,
Examples thereof include methacrylic acid and esters thereof. These mono-olefin compounds are used alone or in combination of two or more kinds for copolymerization with a conjugated diene monomer.

The most preferred diene polymer for the photosensitive elastomer composition for flexographic printing plates is a styrene / butadiene block copolymer, and the developer used in the present invention is most effectively used. Further, the ethylenically unsaturated compound as the component (2) and the photopolymerization initiator as the component (3) are optional from those conventionally used in this type of photosensitive elastomer composition. You can choose to.

Examples of the ethylenically unsaturated compound (2) include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, polyethylene glycol, butylene glycol diacrylate and dimethacrylate, or trimethylolpropane triacrylate and trimethacrylate, pentamethacrylate. Erythritol tetraacrylate and tetramethacrylate, N, N′-hexamethylenebisacrylamide and methacrylamide, styrene, vinyltoluene, divinylbenzene, diacrylphthalate, triallyl cyanurate, fumaric acid diethyl ester, fumaric acid dibutyl ester, Fumaric acid dioctyl ester, Fumaric acid distearyl ester, Fumaric acid butyl octyl ester,
Fumaric acid diphenyl ester, fumaric acid dibenzyl ester, maleic acid dibutyl ester, maleic acid dioctyl ester, fumaric acid bis (3-phenylpropyl)
Esters, dilauryl fumarate, dibehenyl fumarate and the like can be mentioned.

Examples of the photopolymerization initiator (3) include benzophenone, Michler's ketone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether,
α-methylolbenzoin, α-methylolbenzoin methyl ether, α-methoxybenzoin methyl ether, benzoin phenyl ether, α-t-butylbenzoin, 2,2-dimethoxyphenylacetophenone,
2,2-diethoxyphenylacetophenone, 2,2-
Examples thereof include diethoxyacetophenone, benzyl, pivaloin, anthraquinone, benzanthraquinone, 2-ethylanthraquinone, and 2-chloroanthraquinone.

Examples of such a photosensitive elastomer composition include, for example, JP-A-47-37521, JP-A-51-106501, JP-A-52-64301, and JP-A-53-127004. Japanese Patent Laid-Open No. 54-
110287, JP-A-55-48744,
Examples thereof include those described in JP-A-58-62640.

The compound represented by the general formula (A) used as a developer is an ester of acetic acid or propionic acid, and examples thereof include n-octyl acetate, n-ethylhexyl acetate, decyl acetate, octyl propionate and decyl propionate. Pionate, cyclohexyl acetate, ethyl cyclohexyl acetate, t-butyl cyclohexyl acetate, cyclohexyl propionate, benzyl acetate, benzyl propionate, 2-phenylethyl acetate, 3-methoxybutyl acetate, 3-methoxybutyl propionate, 3
-Methoxy-3-methylbutyl acetate, 2-butoxyethyl acetate, 2-butoxybutyl acetate,
4-Butoxybutyl acetate, 4- (4'-methoxybutoxy) butyl acetate and the like can be mentioned as an example.

In the present invention, dodecylbenzene or limonene can be used as the developer. Further, the above compounds may be used alone or in combination with a compound having a boiling point difference of 20 ° C. or less under normal pressure. For example, as a combination example, any combination having a close boiling point, that is, 3-methoxybutyl acetate and cyclohexyl acetate, benzyl acetate and benzyl propionate, 2-ethylhexyl acetate and 2-butoxyethyl acetate, D-limonene and cyclohexyl, Acetate etc. can be mentioned as an example. Further, a substance containing an isomer produced in an industrial production process, such as nonyl acetate, can be similarly used.

The cellulose derivative used as the release layer includes ethyl cellulose, cellulose acetate,
Examples thereof include cellulose butyrate and cellulose acetate butyrate.

Among the compounds represented by the general formula (A), compared to the solubility of the photosensitive elastomer composition, less swelling to the cured product occurs, and there are few defects such as fine lines, fine dots, and fine letters during development. Further, from the viewpoint that the drying after development can be performed in a relatively short time, CH ₃ COOC _n H _2n OC _m H _{2m + 1} (n + m
= ≦ 5, n = ≧ 1, m = ≧ 1), an alkoxyalkyl acetate represented by the formula: CH ₃ COO (C _n H _2n O) ₂
Alkoxypolyoxyalkylenyl acetate represented by C _m H _{2m + 1} (n = 2 to 6, m = 1 to 4) is particularly preferable.

When a photosensitive elastomer composition is developed using a chlorine-based developing solvent that has been used conventionally, after drying, the surface of the cured product is stained with an orange peel-like pattern called orange peel. Therefore, a step of wiping the plate surface with a new developing solvent is required. On the other hand, when developed with the developing solvent of the present invention, such an orange pigment
In particular, CH ₃ COOC _n H _2n OC _m H
_When developing with an alkoxyalkyl acetate represented by _{2m + 1} (n + m ≦ 5, n ≧ 1, m ≧ 1), no orange peel is generated, so the surface of the cured product is dried with a new developing solution. It has the advantage that it does not need to be wiped off. Particularly, 3-methoxybutyl acetate shows excellent properties.

In the present invention, washing out with a developer is usually carried out by brushing or spraying with a spray. Since heating of the developing solution is not particularly required, a commercially available developing device can be used as it is.

Since the developer used in the present invention has a flash point higher than room temperature, it is not particularly dangerous in normal operation, but it is an inflammable source such as a spark because it is a combustible material. If the product to be obtained has a structure that may come into contact with the developer or air containing a large amount of developer vapor, it is desirable to take safety measures such as partitioning.

[0023]

EXAMPLES The present invention will be described in detail below with reference to examples. Example 1 Polystyrene-polybutadiene-polystyrene block copolymer (styrene content 40%) 3 kg, liquid 1,2-
Polybutadiene 1kg, Dioctyl Fumarate 400
g, 100 g of lauryl maleimide, and 100 g of 2,2-dimethoxy-2-phenylacetophenone were kneaded to obtain a photosensitive elastomer composition, and a 100 μm-thick polyester film and a polyester film of the same thickness coated with soluble cellulose acetate were used as scissors. 3m
It was placed inside a m-thick spacer and pressed at 110 ° C. to obtain a sheet of a photosensitive elastomer composition having a cellulose acetate release layer on one side. This sheet 30 × 2
The following examination was performed using 0 cm.

After exposure to 880 mj · cm ^-2 from the side opposite to the surface coated with cellulose acetate with an ultraviolet fluorescent lamp, the polyester film on the surface coated with cellulose acetate was peeled off, and the transparent image carrier was adhered with a vacuum sheet. An exposure of 6000 mj · cm ^-2 was performed with an ultraviolet fluorescent lamp to form a relief.

3-Methoxybutylacetate as a developer
When the unexposed area was eluted with a rotary brush type developing machine using a printer, a relief that faithfully reproduced the current image was obtained by developing for 8 minutes, and the cellulose acetate release layer on the relief surface was obtained. Was completely dissolved. When the swelling ratio was calculated from the thickness of the sheet at this time, it was found to be 4.0% swelling before the development.

When this sheet was dried at 60 ° C. for 1 hour, the plate thickness was completely restored to the state before development. There is no missing of relief, the depth of the white line 400μ is 1
It was 00μ. In addition, the orange peel on the relief surface
No le was observed. This sheet is equipped with GL (sterilization lamp) and CL (ultraviolet lamp) lamps for 550,
After post-exposure of 1000 mj · cm ⁻² , printing was performed with a flexographic printing machine, and a good quality printed matter was obtained.

Example 2 Tables 1 to 4 show the results obtained by washing out the uncured portion by variously changing the kinds of the cellulose derivative and the developer as the release layer by the method according to Example 1. In all of these cases, the release layer was completely dissolved from the relief surface after development.

[0028]

[Table 1]

[0029]

[Table 2]

[0030]

[Table 3]

[0031]

[Table 4]

Example 3 Polystyrene-polyisoprene-polystyrene block copolymer 3 kg, polyvinyltoluene 138 g, 1,6
-Hexanediol diacrylate 137g, 1,6-
Hexanediol Dimethacrylate 117g, 2,2-
55 g of dimethoxyphenylacetophenone was kneaded with a kneader at 130 ° C. The obtained photosensitive elastomer composition was washed in the same manner as in Example 1 except that cellulose acetate was used as the release layer and the type of the developer was variously changed to wash out the uncured portion. .. In all of these cases, the release layer was completely dissolved from the relief surface of the developer.

[0033]

[Table 5]

Comparative Example 1 In the same manner as in Example 1, a polyamide-based material was used as the release layer, and the uncured portion was washed out with various types of developers. As a result, in all cases, the release layer did not completely fall from the plate surface after development, and it was not ready for use as a printing plate as it was. Further, a large amount of the peeled off peeling layer was floating in the developing machine.

[0035]

According to the method for plate-making a photosensitive elastomer composition using the specific release layer and the developer of the present invention, the release layer can be completely dissolved and removed, and the problem of orange peel, which has been a problem in the past, is widespread. The effect of being improved is obtained.

Claims (1)

[Claims] 1. A plate-making method for obtaining a printing plate by imagewise exposing and developing a photosensitive resin composition comprising a support / a diene rubber-based photosensitive elastomer composition / a release layer, wherein a cellulose derivative is used as a release layer, Further, as a developer, an ester represented by the following general formula (A) or a compound selected from dodecylbenzene and limonene is used alone,
Alternatively, a plate-making method characterized by using it in combination with a compound having a boiling point difference of 20 ° C. or less under normal pressure. R ¹ COOR ² ……………… (A) [wherein R ¹ is CH ₃ or C ₂ H ₅ and R ² is —C _n
An alkyl group represented by H _{2n + 1} (n = 6 to 10), -C
₆ H ₁₀ X substituted or unsubstituted cyclohexyl group represented by (X = H, alkyl group having 1 to 4 carbon atoms), -C _n H
_2n · Ar (Ar = an aromatic group, n = 1, 2) aralkyl group represented _{by, - (C n H 2n O} ) a C m H 2m + 1 (n = 2
˜6, m = 1 to 4, a = 1 or 2, a / (na + m)
Represents an alkoxypolyoxyalkylenyl group represented by ≦ 1/4].