JP3049863B2 - Method for developing photosensitive elastomer composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. 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 portion of the photosensitive elastomer composition with a soluble solvent. I have.

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

[0004] The release layer is provided for the purpose of facilitating the adhesion to the transparent image carrier, and must be soluble in a developing solution in a developing step in plate making.
When the release layer is a polyamide-based material, n-butanol is used for the purpose of enabling dissolution of the film in a developer.
Alcohol-based organic solvents such as isopropanol have been used by being mixed with chlorine-based organic solvents.

[0005]

Since such a chlorine-based organic solvent does not have flammability, it has an advantage in terms of safety in handling, but has a problem in hygiene such as being highly toxic to the human body. In addition, the development of a non-chlorine-based developing solvent has been desired from the viewpoint of improving the working environment and preventing air pollution, for example, because it contributes to ozone layer destruction. Further, in the case of a chlorine-based developing solvent which has been conventionally used, the swelling of the photosensitive elastomer composition cured material which becomes the image area is large, and thin lines and fine dots in the image area are damaged during the development process, or It has drawbacks such as a long drying time required for recovery from swelling. Improvements are also desired in this regard, and non-chlorine-based developers have been developed to meet this demand.

[0006] As a non-chlorine-based developer, EP035578 is used.
No. 9, JP-A-62-160446, US Pat.
Techniques described in No. 2 and the like can be cited as prior art, but they do not describe a release layer.
However, in fact, many photosensitive elastomer compositions for flexographic printing currently available on the market use a polyamide-based material as a release layer, so that when these are developed, the release layer can be dissolved. For this purpose, an alcohol-based solvent must be added and used.

[0007] In the conventional chlorine-based developer, the ratio of the chlorine-based solvent to 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-based developer has a problem that it is difficult to adjust the mixing ratio of the distilled and recovered liquid because the specific gravity of the two components is close.

[0008]

SUMMARY OF THE INVENTION The present invention has been studied in order to solve the above problems, and as a result, a specific single organic solvent, Alternatively, the present inventors have found that it is possible to use as a developer a combination of those having a boiling point difference of not more than 20 ° C. at normal pressure, thereby achieving the object, and have completed the present invention.

Accordingly, the present invention uses a cellulose derivative as a release layer of the photosensitive elastomer composition surface and a compound selected from the esters or dodecyl benzene represented by the following general formula (A) as a developing agent It is an object of the present invention to provide a plate-making method characterized in that it is used alone or in combination with a compound having a boiling point difference of 20 ° C. or less at normal pressure. R ¹ COOR ² ... (A) wherein R ¹ is CH ₃ or C ₂ H ₅ , and R ² is — (C _n H _2n
O) represents an alkoxypolyoxyalkylenyl group represented by _a C _m H _{2m + 1} (n = 2 to 6, m = 1 to 4, a = 1 or 2, a / (na + m) ≦ １ ／) ].

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

As the diene polymer (1), a polymer obtained by homopolymerizing a conjugated diene monomer or copolymerizing with a monoolefin compound is used. Examples of the conjugated diene monomer include butadiene, isoprene, and chloroprene. Further, as the monoolefin compound used for copolymerization with a conjugated diene monomer, styrene, α-methylstyrene, vinyltoluene, acrylonitrile, acrylic acid,
Examples thereof include methacrylic acid and esters thereof. These monoolefin 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. The ethylenically unsaturated compound as the component (2) and the photopolymerization initiator as the component (3) may be any of those commonly used in this type of photosensitive elastomer composition. You can choose.

As the ethylenically unsaturated compound (2), diacrylates and dimethacrylates of ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, polyethylene glycol and butylene glycol, or trimethylolpropane triacrylate and trimethacrylate, pentane Erythrit tetraacrylate and tetramethacrylate, N, N'-hexamethylenebisacrylamide and methacrylamide, styrene, vinyltoluene, divinylbenzene, diacrylphthalate, triallyl cyanurate, diethyl fumarate, dibutyl fumarate, Dioctyl fumarate, distearyl fumarate, butyl octyl fumarate,
Diphenyl fumarate, dibenzyl fumarate, dibutyl maleate, dioctyl maleate, bis (3-phenylpropyl) fumarate
Esters, dilauryl fumarate, dibehenyl fumarate, and the like.

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-methylol benzoin, α-methylol benzoin methyl ether, α-methoxy benzoin methyl ether, benzoin phenyl ether, α-t-butyl benzoin, 2,2-dimethoxyphenyl acetophenone,
2,2-diethoxyphenylacetophenone, 2,2-
Examples include diethoxyacetophenone, benzyl, pivaloin, anthraquinone, benzuansuraquinone, 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. No., JP-A-54-
110287, JP-A-55-48744,
JP-A-58-62640 and the like can be mentioned as examples.

The compounds represented by the general formula to be used as a developer (A) is acetic acid or propionic acid, For example 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 given as examples.

Further, as the developer in the present invention can be used dodecyl benzene. Further, the above compounds can be used alone or in combination with a compound having a boiling point difference of 20 ° C. or less at normal pressure. For example, as an example of the combination, any combination having a close boiling point, that is, 3
-Methoxybutyl acetate and cyclohexyl acetate, 3-methoxybutyl acetate and ethylene glycol
Monoethyl ether acetate, 2-ethylhexyl acetate and 2-butoxyethyl acetate tape preparative like can be cited as an example. Further, those containing isomers produced in industrial production processes, such as nonyl acetate, can also be used.

As the cellulose derivative used as the release layer, ethyl cellulose, cellulose acetate,
Examples include cellulose butyrate and cellulose acetate butyrate.

Among the compounds represented by the general formula (A), the swelling of the cured product is small and the fine lines, fine dots, fine characters and the like are less chipped during development, as compared with the solubility of the photosensitive elastomer composition. Further, from the viewpoint that 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) or 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 preferred.

When the photosensitive elastomer composition is developed using a chlorine-based developing solvent which has been conventionally used, after drying, a stain such as orange peel called orange peel is formed on the surface of the cured product. Therefore, a step of wiping the plate surface with a new developing solvent was required. On the other hand, when development is performed using the developing solvent of the present invention, such an orange peak can be obtained.
And CH ₃ COOC _n H _2n OC _m H
_When developing using an alkoxyalkyl acetate represented by _{2m + 1} (n + m ≦ 5, n ≧ 1, m ≧ 1), no orange peel is generated. It has the advantage of not having to be wiped off. In particular, 3-methoxybutyl acetate shows excellent properties.

In the present invention, washing out with a developer is usually performed 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. However, since it is a combustible material, it can be used as an ignition source such as a spark. If what is to be obtained is a structure that may come into contact with air containing a large amount of developer or developer vapor, it is desirable to take safety measures such as partitioning.

[0023]

The present invention will be described below in detail with reference to examples. Example 1 3 kg of polystyrene-polybutadiene-polystyrene block copolymer (styrene content 40%), liquid 1,2-
Polybutadiene 1kg, Dioctyl fumarate 400
g, laurylmaleimide 100g, and 2,2-dimethoxy-2-phenylacetophenone 100g are sandwiched between a 100 µm-thick polyester film and a polyester film of the same thickness coated with soluble cellulose acetate. , 3m
It was placed inside a spacer having a thickness of m 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 study was performed using 0 cm.

After performing exposure at 880 mj · cm ^{−2 with} an ultraviolet fluorescent lamp from the side opposite to the cellulose acetate-coated surface, the polyester film on the cellulose acetate-coated surface is peeled off, and the transparent image carrier is brought into close contact with a vacuum sheet. Exposure was performed at 6000 mj · cm ^{−2 with} an ultraviolet fluorescent lamp to form a relief.

3-methoxybutyl acetate as a developer
The unexposed areas were eluted with a rotary brush-type developing machine using a developer, and a relief that faithfully reproduced the current image was obtained after 8 minutes of development, and the cellulose acetate release layer on the relief surface was obtained. Was completely dissolved. When the swelling ratio was determined from the thickness of the sheet at this time, the swelling ratio was 4.0% before development.

When the sheet was dried at 60 ° C. for 1 hour, the plate thickness was completely restored to the state before development. No relief was seen, and the depth of the 400μ wide outline was 1
00μ. In addition, orange pea on the relief surface
Was not observed at all. A GL (germicidal lamp) and a CL (ultraviolet lamp) lamp were added to this sheet for 550, respectively.
After performing post-exposure at 1000 mj · cm ⁻² , printing was performed with a flexographic printing machine. As a result, a high quality printed matter was obtained.

Examples 2 to 7 and Comparative Examples 1 to 8 The results obtained by washing out the uncured portions by changing the type of the cellulose derivative and the developer as the release layer in various manners in the same manner as in Example 1 are shown. 1 to 4. 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]

Examples 8 to 10, Comparative Examples 9 to 11 3 kg of polystyrene-polyisoprene-polystyrene block copolymer, 138 g of polyvinyl toluene, 1,6
-Hexanediol diacrylate 137 g, 1,6-
Hexanediol dimethacrylate 117 g, 2,2-
55 g of dimethoxyphenylacetophenone was kneaded at 130 ° C. in a kneader. Table 5 shows the results obtained by washing out the uncured portion of the obtained photosensitive elastomer composition by using a method similar to that of Example 1, using cellulose acetate as the release layer, and changing the type of the developer in various ways. In all these cases, the release layer was completely dissolved from the relief surface of the developer.

[0033]

[Table 5]

Comparative Example 12 By a method similar to that of Example 1, an uncured portion was washed out by using a polyamide-based material for the release layer and changing the type of developer in various ways. As a result, in all cases, the release layer did not completely fall from the plate surface after development, and the plate could not be used as it was as it was. Further, the peeled-off peeling layer was floating in a large amount in the developing machine.

[0035]

According to the plate making method of the photosensitive elastomer composition using the specific release layer and the developer according to 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 also large. Is obtained.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-167552 (JP, A) JP-A-58-10732 (JP, A) JP-A-57-208556 (JP, A) JP-A-2- 257141 (JP, A) JP-A-62-160446 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03F ^7/ 00-7/42

Claims (1)

(57) [Claims] 1. A plate-making method for obtaining a printing plate by image exposure and development from a photosensitive resin composition comprising a support / diene rubber-based photosensitive elastomer composition / release layer, wherein a cellulose derivative is used as a release layer, and used in combination esters represented by the following general formula (a) as a developing agent or dodecyl <br/> benzenoid compound selected from among down alone, or a compound within the boiling point difference 20 ° C. under normal pressure A plate-making method, characterized in that: R ¹ COOR ² ... (A) wherein R ¹ is CH ₃ or C ₂ H ₅ , and R ² is — (C _n H _2n
O) represents an alkoxypolyoxyalkylenyl group represented by _a C _m H _{2m + 1} (n = 2 to 6, m = 1 to 4, a = 1 or 2, a / (na + m) ≦ １ ／) ].