JP2001188356A - Developer for photosensitive elastomer composition and plate making method using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developer which is a chlorine-free organic solvent, causes slight swelling in development, dissolves both polyamide and cellulose protective films, is excellent in preservation stability at low temperature and is used in the formation of an image form a photosensitive elastomer composition with high environmental and hygienic safeties and a plate making method using the developer. SOLUTION: The developer comprises a three-component mixed solvent consisting of 20-50% aliphatic or alicyclic hydrocarbon, 20-50% aromatic hydrocarbon and 15-35% benzyl alcohol.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developer used for forming an image from a photosensitive elastomer composition and a plate making method using the same, and more particularly, to a developing method suitable for making a flexographic printing plate. The present invention relates to an agent and a plate making method using the same.

[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 washing away unexposed portions. The solvent used at this time is called a developer, and a solvent in which the photosensitive elastomer composition is soluble is used. Conventionally, photosensitive elastomer compositions used for making a flexographic printing plate generally include (a) a diene-based polymer, (b) an ethylenically unsaturated compound, and (c) a photopolymerization initiator as main components. Therefore, unexposed portions cannot be washed away with water or an aqueous solvent, and therefore, chlorine-based organic solvents such as tetrachloroethylene and 1,1,1-trichloroethane have been used exclusively as a developer.

[0003] Generally, a commercially available photosensitive elastomer composition for flexographic printing is formed into a plate by extrusion or press molding, and has a structure sandwiched between a support and a protective film. Among them, the protective film is provided for the purpose of facilitating the adhesion to the transparent image carrier, and polyamides and cellulose derivatives are mainly used. Therefore, the developer must dissolve the photosensitive elastomer composition and the protective film.

When the protective film is made of a cellulosic material, it is soluble in a chlorine-based organic solvent, but when it is made of a polyamide material, it is insoluble or hardly soluble, so that it can be dissolved in a film developer. For this purpose, alcohol-based organic solvents such as 1-butanol and isopropanol have been used by being mixed with chlorine-based organic solvents. However, such chlorinated organic solvents have low flammability and therefore have an advantage in terms of safety in handling, but on the other hand, they have problems in terms of hygiene such as strong toxicity to the human body. The development of a non-chlorine-based developing solvent has been desired from the viewpoint of work environment and prevention of air pollution, for example, because it contributes to destruction.

On the other hand, in the case of a chlorine-based developing solvent which has been conventionally used, the swelling of the cured photosensitive elastomer composition as an image portion is large, and the fine lines and fine dots in the image portion are damaged in the developing step. Therefore, improvement is desired also from this point, and a non-chlorine-based developer is being developed in order to respond to this. There are several prior arts as chlorine-free developers so far, but none of them completely solves the above problems.

For example, JP-A-2-7056 discloses a boiling point range of 160 to 220 ° C. and a flash point of 45 ° C.
It is based on a hydrogenated petroleum fraction higher than 0 ° C., and it is disclosed that a polyamide-based protective film can be dissolved in combination with an aliphatic alcohol, but it cannot dissolve a cellulose-based protective film. However, the function of the developer is insufficient. Further, since the conductivity of the developer is low, a strong electrostatic charge may be generated in the developing device, and handling is complicated because it is dangerous and requires the addition of an antistatic agent.

Japanese Patent Application Laid-Open No. Sho 62-160446 discloses a developer containing monoterpene as a main component and containing alcohol or ketone. Problem. Japanese Patent Application Laid-Open No. Hei 4-500278 discloses an apparatus using an ester as a main component, but has a strong odor and also has a problem in terms of working environment. JP-A-2-255
Japanese Patent Publication No. 385 discloses a composition containing a terpene-based hydrocarbon as a main component, but the exemplified limonene has a strong odor and skin irritation, and has a problem in working environment. Japanese Patent Application Laid-Open No. 2-179645 discloses a developer containing a benzene derivative as a main component. When a polyamide-based protective film is provided, a high-boiling alcohol can be contained. Some derivatives have a strong pungent odor, which often causes a problem in the working environment.

Japanese Patent Application Laid-Open No. Hei 5-249695 discloses that benzyl alcohol which has a high solubility for a protective film but cannot be used due to poor compatibility with aliphatic or alicyclic hydrocarbons is used as a compatibilizer. Are disclosed, which can be used by adding a compound or an acetate, and have excellent protective film solubility. However, when the developer is stored at a low temperature, phase separation may occur. Also,
Addition of these compatibilizers has the disadvantage that the solubility of the photosensitive elastomer composition and the protective film is reduced, and the developing speed is low. In addition, since it has low conductivity and is liable to generate electrostatic charge, it requires addition of an antistatic agent, and handling is complicated. As described above, the conventional photosensitive elastomer composition developer for flexographic printing plates that replaces the conventional chlorine-based organic solvent is an environment, hygiene, security surface, or a polyamide system provided on the elastomer composition surface, There is a problem in that both of the cellulose-based protective films cannot be dissolved, and a developer suitable for developing all commercially available photosensitive elastomer compositions having high safety has been desired.

[0009]

SUMMARY OF THE INVENTION The present invention provides a developer used for forming an image from a photosensitive elastomer composition and a plate making method using the same, which can simultaneously satisfy the following requirements. With the goal. 1) It is a chlorine-free organic solvent, and the swelling of the cured photosensitive elastomer composition during development is small. 2) Dissolve both polyamide-based and cellulose-based protective films. 3) High safety because of high conductivity and low electrification. 4) Excellent storage stability at low temperatures. 5) Environmental and sanitary safety is relatively high. (Low odor.)

[0010]

The present inventors have conducted intensive studies and as a result, as a developer used when forming an image from the photosensitive elastomer composition, a boiling point range of 150 ° C. to 2 ° C.
An aliphatic or alicyclic hydrocarbon having a temperature of 40 ° C., 20 to 50;
It has been found that the above problem can be solved by using an organic solvent mixture consisting of a ternary mixed solvent of 20 to 50% by weight of an aromatic hydrocarbon having a boiling point range of 150 to 240 ° C. and 15 to 35% by weight of benzyl alcohol. Thus, the present invention has been completed.

Hereinafter, the present invention will be described in more detail. The photosensitive elastomer composition suitable for plate making by the development method of the present invention is mainly composed of (1) a diene polymer, (2) an ethylenically unsaturated compound, and (3) a photopolymerization initiator. is there. As the diene-based polymer (1), a polymer obtained by homopolymerizing a conjugated diene-based monomer or copolymerizing with a monoolefin-based compound is used. Butadiene, conjugated diene monomers
Examples include isoprene and chloroprene.

Further, examples of the monoolefin compound used for copolymerizing with the conjugated diene monomer include styrene, α-methylstyrene, vinyltoluene and the like. 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 polymers for the photosensitive elastomer composition for flexographic printing are a styrene / butadiene block copolymer and a styrene / isoprene block copolymer, and the developer used in the present invention is most preferably 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.

Examples of the ethylenically unsaturated compound (2) include diacrylates and dimethacrylates of alkanediols such as hexanediol and nonanediol, or ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, polyethylene glycol, butylene. Glycol diacrylate and dimethacrylate, or trimethylolpropane triacrylate and trimethacrylate, pentaerythritol tetraacrylate and tetramethacrylate, N, N'-hexamethylenebisacrylamide and methacrylamide, styrene, vinyltoluene,
Divinylbenzene, diacryl phthalate, triallyl cyanurate, diethyl fumarate, dibutyl fumarate, dioctyl fumarate, distearyl fumarate, butyl octyl fumarate, diphenyl fumarate, dibenzyl fumarate, Examples include dibutyl maleate, dioctyl maleate, bis (3-phenylpropyl) fumarate, 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 feinyl ether, α-
t-butylbenzoin, 2,2-dimethoxyphenylacetophenone, 2,2-diethoxyphenylacetophenone, benzyl, pivaloin, anthraquinone, benzuansuraquinone, 2-ethylanthraquinone, 2-chloroanthraquinone, and the like. it can.

Examples of such a photosensitive elastomer composition include, for example, JP-A-47-37521, JP-A-51-106501, and JP-A-52-64301.
JP, JP-A-53-137004, JP-A-54
JP-A-110287, JP-A-55-48744, JP-A-58-62640 and the like can be mentioned as examples. The photosensitive elastomer composition is formed into a plate shape by extrusion molding or press molding, and has a structure sandwiched between a support and a protective film. As the support, a dimensionally stable 75 to 300 μm film such as polyester ferm can be used,
An adhesive may be used as needed between the photosensitive elastomer composition layer and the photosensitive elastomer composition layer. The protective film is provided for the purpose of facilitating the close contact with the transparent image carrier, and mainly uses polyamides and cellulose derivatives. Examples of the cellulose derivative include ethyl cellulose, cellulose acetate, cellulose butyrate, cellulose acetate butyrate, and the like.

The aliphatic or alicyclic hydrocarbon used in the developer of the present invention is mainly a petroleum fraction obtained by distilling crude oil, from which aromatic compounds are removed by hydrorefining and fractionating. A mixture of chain paraffins such as n-paraffin and isoparaffin and a naphthenic compound, or a mixture obtained by mixing a synthetic paraffin and a naphthenic compound. Such products include, for example, Exxol (trade name) D60 manufactured by Exxon Chemical Co., Ltd. Petroleum hydrocarbons can be mentioned as examples.

Examples of the aromatic hydrocarbon include n-propylbenzene, isopropylbenzene, n-butylbenzene, isobutylbenzene, sec-propylbenzene, n-pentylbenzene, 1-methyl-2-ethylbenzene, 1-methyl- 3-ethylbenzene, 1-methyl-2-ethylbenzene, 1,2-diethylbenzene,
1,3-diethylbenzene, 1-methyl-3-propylbenzene, 1-methyl-4-propylbenzene, 1-methyl-4-isopropylbenzene, 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene , 1,
Examples thereof include 3,5-trimethylbenzene, 1,2,3,5-tetramethylbenzene, 1,2,4,5-tetramethylbenzene, dimethylethylbenzene, naphthalene, indane, and indenemethylindane. These can be used alone or in a mixture of two or more, but those commercially available are mixtures of these several types, or mixtures with aliphatic and alicyclic hydrocarbons. Solvesso (trade) manufactured by Idemitsu Petrochemical Co., Ltd., Ipsol (trade) manufactured by Idemitsu Petrochemical Co., Ltd.
(Quotient) and the like.

The boiling point of the aliphatic or alicyclic hydrocarbon or aromatic hydrocarbon in the developer of the present invention is 150 to 2
It needs to be in the range of 40 ° C. Preferably 18
0-220 ° C. Benzyl alcohol has a boiling point of 20
Since it is 5 ° C., by setting the boiling point range of the aliphatic or alicyclic hydrocarbon and the aromatic hydrocarbon as described above,
When the developer is recovered and reused, the change in composition can be reduced, and the step of readjusting the mixed solvent can be eliminated or simplified.

In the present invention, the mixing ratio of the aliphatic or alicyclic hydrocarbon, aromatic hydrocarbon and benzyl alcohol is determined by the solubility of the photosensitive elastomer composition and the protective film, the swelling ratio of the cured photosensitive elastomer composition, Electrostatic charging,
It is determined in consideration of the storage stability of the developer, the time required for development, and the like. 20-50 aliphatic or alicyclic hydrocarbons
%, Preferably in the range of 30 to 40% by weight. If the amount is less than 20% by weight, the mixing ratio of the aromatic hydrocarbon increases, which causes problems such as odor. If the amount is more than 50% by weight, problems such as a decrease in development speed and an increase in electrostatic charge arise.

The aromatic hydrocarbon is used in the range of 20 to 50% by weight, preferably in the range of 30 to 45% by weight.
If it is less than 20% by weight, a sufficient developing speed cannot be obtained.
If the amount is more than 50% by weight, problems such as odor and the like, and the swelling of the cured photosensitive elastomer composition becomes large. Swelling is not preferred because it causes a phenomenon (chipping) in which a part of the image is lost during development. Benzyl alcohol is in the range of 15-35% by weight, preferably 2%.
It is used in the range of 0 to 30% by weight. If the amount is less than 15% by weight, the solubility of the protective film becomes insufficient. If it is more than 35% by weight, the solubility of the photosensitive elastomer composition is reduced.

In the present invention, the conductivity is used as an index for the tendency of the electrostatic charge of a solvent or the like to occur. Generally, when the conductivity is large, it is difficult to be charged. The value of the electric conductivity is preferably ≧ 1000 pS · m ⁻¹ , particularly preferably ≧ 10000 pS
S · m ⁻¹ . Washing out using a developer in the present invention is usually performed by brushing or spraying, and 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 flammable, it can be used as a source of ignition such as sparks. If the structure has a possibility of coming into contact with air containing a large amount of liquid or developer vapor, it is desirable to take safety measures such as partitioning.

As described above, the developer comprising an aliphatic or alicyclic hydrocarbon, an aromatic hydrocarbon, and benzyl alcohol in the developer of the present invention has the following characteristics. 1) It is a chlorine-free organic solvent, and the swelling of the cured photosensitive elastomer composition during development is small. 2) Dissolve both polyamide-based and cellulose-based protective films. 3) High conductivity and no need for an antistatic agent. 4) Excellent storage stability at low temperatures. 5) Environmental and sanitary safety is relatively high. (Low odor.)

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to examples and comparative examples. The compositions in Examples and Comparative Examples are weight ratios. The evaluation method in the examples will be described below. Protective film solubility is as follows: when the polyamide-based or cellulose-based protective film is immersed in a solvent and completely dissolved,
It was expressed by. The swelling ratio was AFPHF-10 as a resin composition comprising a support / photosensitive elastomer composition / protective film.
(Trade name, manufactured by Asahi Kasei Kogyo) from the protective film side to 6000 mJ
After exposure to cm ^−2, the plate was immersed in a solvent for 2 minutes, the thickness of the exposed plate was measured, and the swelling ratio was determined.

The conductivity is digital ultra-high resistance / micro ammeter R
The volume resistivity of the solvent was measured using Model 8340A (manufactured by Advantest), and the volume resistivity was determined from its reciprocal. The low-temperature storage stability was represented by ○ when no phase separation or white turbidity occurred when the developer was stored for 1 month in an insulated container at 0 ° C., and x when it occurred. For odors, those with strong irritating odor and unpleasant odor ×, irritating odor,
Those having no or slight unpleasant odor were indicated by ○.

(Experiment 1) 3 kg of polystyrene-polybutadiene-polystyrene block copolymer, liquid 1,2-
Polybutadiene 1kg, dioctyl fumarate 400
g, laurylmaleimide 100 g, 2,2-dimethoxy-2-phenylacetophenone 100 g of the photosensitive elastomer composition obtained by kneading a polyester film having a thickness of 100 μm and a polyester film having the same thickness coated with soluble cellulose acetate, 3mm
And pressed at 110 ° C. to obtain a sheet of a photosensitive elastomer composition having a cellulose-based protective film on one side.

The sheet was cut into a size of 30 × 20 cm, exposed to ultraviolet light at 880 mJ · cm ⁻² from the side opposite to the cellulose acetate coated surface, and the polyester film on the cellulose acetate coated surface was peeled off.
The transparent image carrier was brought into close contact with a vacuum sheet, and exposed at 6000 mJ · cm ⁻² with an ultraviolet fluorescent lamp to form a relief. The unexposed portion is eluted with a flat brush type developing machine using a developer, and a developing time for obtaining a relief faithfully reproducing the original image is obtained.
After drying for 1 hour at, the relief surface was observed, and the presence or absence of relief chipping was examined.

(Experiment 2) 3 kg of polystyrene-polyisoprene-polystyrene block copolymer, 138 g of polyvinyl toluene, 137 g of 1,6-hexanediol diacrylate, 117 g of 1,6-hexanediol dimethacrylate, 55 2,2-dimethoxyacetophenone
g of the photosensitive elastomer composition obtained by kneading the mixture with a 100 μm-thick polyester film and a polyamide-coated polyester film of the same thickness.
And pressed at 110 ° C. to obtain a sheet of a photosensitive elastomer composition having a polyamide-based protective film on one side. The following experiment was performed using this sheet 30 x 20 cm.

UV light from the side opposite to the polyamide
660mJ · cm with light lamp^-2After exposure of
Remove the polyester film on the mid-coating surface and clear
The image carrier is brought into close contact with a vacuum sheet,
5000mJ ・ cm with light lamp ^-2Exposure to relief
Was formed. Not using a flat brush type developing machine with developer
Relief that faithfully reproduces the original image by eluting the exposed part
Is determined at 60 ° C. for 1 hour.
After drying for an hour, observe the relief surface and
Was examined.

[0029]

Examples 1 to 5 The solubility of a protective film and the swelling ratio of a cured product of a photosensitive elastomer composition were determined using a developer having the composition shown in Table 1.
The conductivity, low-temperature storage stability, and odor were evaluated. Experiments 1 and 2 were conducted for the developers of Examples 1 to 5.
The development time and the presence or absence of chipping in the relief were evaluated. Table 2 shows the results.

[0030]

[Table 1]

[0031]

[Table 2]

[0032]

Comparative Examples 1 to 6 The solubility of the protective film and the swelling ratio of the cured product of the photosensitive elastomer composition were determined using the developers having the compositions shown in Table 3.
The conductivity, low-temperature storage stability, and odor were evaluated. Table 4 shows the results. Further, with respect to the developers of Comparative Examples 1 to 5, the development time and the presence / absence of the relief were evaluated from Experiments 1 and 2. Table 4 shows the results.

[0033]

[Table 3]

[0034]

[Table 4]

[0035]

The developer of the present invention is a non-chlorine organic solvent and can completely dissolve the photosensitive elastomer composition and the protective film of both polyamide and cellulose materials simultaneously and has a low odor. The developing method of the present invention using this developer has no problem in terms of working environment and air pollution, and has a higher conductivity, so that it is difficult to be charged electrostatically, and there is a problem in security. In addition, there is an effect that a high quality printed matter in which the damage of the image portion is reduced without lowering the developing speed can be obtained.

Claims (2)

[Claims] 1. An aliphatic or alicyclic hydrocarbon having a boiling point of 150 to 240.degree. C., 20 to 50% by weight, an aromatic hydrocarbon having a boiling point of 150 to 240.degree. A developer for a photosensitive elastomer composition, comprising 35% by weight of a mixed solvent of three components. 2. A plate making method for obtaining a printing plate from a photosensitive elastomer composition by image exposure and development.
A plate-making method comprising using the developer described in the above.