JP2679193B2 - Photopolymerizable composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a photopolymerizable composition, and more particularly, to a photopolymerizable composition having stable photosensitivity over time and excellent reproducibility.

[Prior Art and Problems to be Solved by the Invention] Photopolymerizable compositions are widely used in the production of printed circuit boards, integrated circuits, metal relief images and printing plates. This photopolymerizable composition usually contains a thermoplastic polymer binder, an addition polymerizable compound, a photopolymerization initiator and the like. Then, a solution-type photopolymerizable composition or a dry film-form photopolymerizable composition dissolved in an organic solvent is applied or laminated on the surface of a copper-clad laminate for a printed board or a metal substrate to be subjected to fine processing. The resist image is formed by laminating, exposing a predetermined pattern with actinic rays, curing the exposed portion, and developing the unexposed portion with a developing solution. Therefore, the photopolymerizable composition is required not only to have a high sensitivity to actinic rays and a high photosensitive curing speed, but also to have stable photosensitive curing characteristics. Further, it is necessary that the characteristics do not deteriorate during storage and the photocurability is stable for a long period of time.

However, according to the conventional photopolymerizable composition, the compatibility between the photopolymerization initiator and the thermoplastic polymer binder or the like is not sufficient, or even if a certain amount of light is irradiated, the curability varies, It is difficult to photosensitize with good reproducibility.
In addition, reproducibility is reduced by long-term storage.

An object of the present invention is to provide a photopolymerizable composition which shows stable photosensitive characteristics and has excellent reproducibility.

[Constitution of the Invention] As a result of intensive studies, the present inventors have found that a photopolymerizable composition containing a specific compound is excellent in stability and reproducibility. That is, the present invention provides (1) a thermoplastic polymer binder, (2) an addition polymerizable compound which is liquid or solid at room temperature and normal pressure, (3) a photopolymerization initiator, and (4) general formula (I). (Wherein R ₁ represents a hydrogen atom, an alkyl group, an aryl group or a halogen atom which may be substituted, and R ₂ represents an alkyl group or an aryl group which may be substituted). A photopolymerizable composition containing a compound solves the above problems.

First, the thermoplastic polymer binder will be described. The thermoplastic polymer binder is not particularly limited, and various thermoplastic resins can be used, such as acrylic ester and / or
Alternatively, a homopolymer or copolymer of methacrylic acid ester, or a copolymer of styrene-based monomer and acrylic acid ester and / or methacrylic acid ester is preferable.

As the styrene-based monomer, styrene, α-substituted styrene in which the α-position is substituted with an alkyl group or a halogen atom, for example, α-methylstyrene, α-chlorostyrene, etc .; Substituted styrene, for example, substituted substituted styrene, For example, p-methylstyrene, p-ethylstyrene p- (tert-butyl) styrene, etc. are exemplified, and at least one is used. Among the styrene monomers, styrene, α-methylstyrene and the like are preferred.

Examples of the acrylate ester include methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, isobutyl acrylate, tert-butyl acrylate, pentyl acrylate, hexyl acrylate, heptyl acrylate. , Octyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, 2-phenoxyethyl acrylate, phenoxypropyl acrylate and the like.
Examples of the methacrylate include methacrylate corresponding to the above acrylate.
One or more of these acrylates and methacrylates are used.

When the unexposed portion is removed and developed with an alkali developer or the cured film is peeled off, it is effective to copolymerize an addition polymerizable monomer having a carboxyl group.
Examples of such an addition-polymerizable monomer include maleic acid, itaconic acid, methacrylic acid, and acrylic acid.

The thermoplastic polymer can be composed of an appropriate ratio of each monomer.

Examples of the addition polymerizable compound include acrylates and methacrylates which are liquid or solid at normal temperature and normal pressure and have two or more acryloyl groups or methacryloyl groups in the molecule.

Examples of the acrylate having two acryloyl groups in the molecule include ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, propylene glycol diacrylate, and dipropylene glycol. Diacrylate, tripropylene glycol diacrylate, tetrapropylene glycol diacrylate, polypropylene glycol diacrylate, 1,4-butanediol diacrylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, ethylene oxide addition of bisphenol A Diacrylate, bisphenol A propylene oxide adduct dia Acrylate, diacrylate of ethylene oxide adduct of hydrogenated bisphenol A, diacrylate of propylene oxide adduct of hydrogenated bisphenol A, N, N'-methylenebisacrylamide, N, N'-benzylidenebisacrylamide and the like. .

Examples of the acrylate having three or more acryloyl groups in the molecule include glycerin triacrylate,
Examples include trimethylolpropane triacrylate, trimethylolethane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, and dipentaerythritol hexaacrylate.

Examples of the methacrylate having two or more methacryloyl groups in the molecule include methacrylates corresponding to the above acrylates.

At least one of the above acrylates and methacrylates is used, and both may be used as a mixture. In addition,
Monofunctional acrylates and methacrylates may be appropriately used in combination. The amount of the addition-polymerizable compound is not particularly limited as long as it does not impair the characteristics of the photopolymerizable composition, but is usually 10 to 200 parts by weight, preferably 100 to 100 parts by weight of the thermoplastic polymer binder. It is about 20 to 150 parts by weight.

As the photopolymerization initiator, various substances such as substituted or unsubstituted polynuclear quinones, aromatic ketones, benzoins, benzoin ethers, and substituted or unsubstituted thioxanthones can be used.

Examples of the substituted or unsubstituted polynuclear quinones include, for example, 2
-Methylanthraquinone, 2-ethylanthraquinone,
2-propylanthraquinone, 2-tert-butylanthraquinone, octamethylanthraquinone, 1,4-dimethylanthraquinone, 2,3-dimethylanthraquinone, benz [a] anthraquinone, benz [b] anthraquinone, 2-phenylanthraquinone, 2,3 -Diphenylanthraquinone, 1-chloroanthraquinone, 2-chloroanthraquinone, 3-chloro-2-methylanthraquinone, 1,4-naphthaquinone, 9,10-phenanthraquinone,
Examples thereof include 2-methyl-1,4-naphthaquinone, 2,3-dichloronaphthaquinone, and 7,8,9,10-tetrahydronaphthacenequinone.

As aromatic ketones, for example, benzophenone,
4,4'-bis (dimethylamino) benzophenone, 4,4 '
-Bis (diethylamino) benzophenone, 4-methoxy-4'-diethylaminobenzophenone and the like.

Examples of benzoins and benzoin ethers include benzoin, methyl benzoin, ethyl benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin phenyl ether and the like.

Examples of the substituted or unsubstituted thioxanthone include thioxanthone, 2-chlorothioxanthone,
Methylthioxanthone, 2-ethylthioxanthone, 2
-Isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-dibutylthioxanthone and the like.

Examples of other photopolymerization initiators include oxime esters such as benzyl, α, α-diethoxyacetophenone, and benzophenone oxime acetate.

The photopolymerization initiator is used alone or in combination of two or more,
The same or different photopolymerization initiators may be used in combination. The amount of the photopolymerization initiator can be selected within a range that does not deteriorate the curing rate and the properties of the cured film, but is usually 0.01 to 30 parts by weight, preferably 1 to 100 parts by weight of the thermoplastic polymer.
~ 15 parts by weight.

The photopolymerization initiator is, for example, 2,4,5-triarylimidazolyl dimer, 2-mercaptobenzoxazole, leuco crystal violet, tris (4
-Diethylamino-2-methylphenyl) methane and aliphatic or aromatic tertiary amines such as N-methyldiethanolamine, ethyl p-dimethylaminobenzoate are useful in combination.

The photopolymerizable composition of the present invention contains the hydroxybenzoic acid amide compound represented by the general formula (I). In the general formula (I), the alkyl group for R ₁ and R ₂ includes methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl,
Examples thereof include heptyl and octyl groups. As the optionally substituted aryl group for R ₁ and R ₂ , phenyl, naphthyl, 4-methylphenyl, 3,5-dimethylphenyl,
A 4-chlorophenyl group etc. are illustrated. Examples of the halogen atom for R ₁ include bromine, chlorine and fluorine.

Among the compounds represented by the general formula (I), salicylic acid amide compounds are preferable. Examples of preferable salicylic acid amide compounds include salicylic acid methylamide, salicylic acid ethylamide, salicylic acid propylamide, salicylic acid butylamide, salicylic acid heptylamide, salicylic acid hexylamide, salicylic acid naphthylamide, salicylic acid anilide, salicylic acid methylanilide and the like.

The hydroxybenzoic acid amide compound can be added in a wide range, but is usually 0.1 to 30 parts by weight, preferably 1 to 15 parts by weight, based on 100 parts by weight of the thermoplastic polymer binder.

The photopolymerizable composition of the present invention may contain a stabilizer, a coloring agent, a coloring agent for facilitating discrimination of a resist image, a plasticizer for imparting flexibility, if necessary, for suppressing a thermal polymerization reaction and for enhancing storage stability. And the like. Examples of the stabilizer include p-methoxyphenol, hydroquinone, hydroquinone monomethyl ether, tert-butylcatechol and the like, and are used in an appropriate amount as long as the photopolymerizability is not inhibited. As the color former, a leuco compound of a triarylmethane dye is useful. For example, leuco crystal violet, leucomalachite green, mineral salts such as hydrochloride and sulfate of these leuco bodies, p-toluenesulfonate And the like. Examples of the coloring agent include crystal violet, malachite green, Victoria blue, methylene blue and the like. Examples of the plasticizer include phthalic acid esters such as diethyl phthalate, dibutyl phthalate, diheptyl phthalate and dioctyl phthalate; fatty acid esters such as dioctyl adipate and dibutyl diglycol adipate; phosphoric acid esters such as trimethylphosphine;
Examples thereof include sulfonic acid amides such as toluenesulfonic acid amide.

The photopolymerizable composition of the present invention may be a liquid containing no organic solvent, but is usually used in the form of a liquid or a dry film dissolved or dispersed in an organic solvent. Examples of the organic solvent include alcohols such as methanol, ethanol and propanol, esters such as ethyl acetate, ketones such as acetone and methyl ethyl ketone, ethers such as diethyl ether and tetrahydrofuran, halogenated hydrocarbons such as methylene chloride. Examples thereof include types. The dry film is produced, for example, by applying a polymerizable composition to a base film such as a polyethylene terephthalate film and drying, and then laminating a cover film such as a polyethylene film with a pressure roll or the like. The thickness of the photopolymerizable composition of the dry film is not particularly limited as long as the resolution and workability are not reduced, but is usually 5 to 100 μm, preferably 20 to 70 μm.

The photosensitive layer comprising the photopolymerizable composition of the present invention is usually prepared by printing or coating a liquid photopolymerizable composition containing an organic solvent on a support such as a printed circuit board to remove the organic solvent or dry the photopolymerizable composition. It is formed by peeling the cover film of the film and laminating the film on the support with a rubber roll or the like.

The photosensitive layer is a light source that generates chemically active radiation,
For example, exposure is performed with a light source such as a low-pressure mercury lamp, an ultra-high-pressure mercury lamp, and a xenon lamp. Exposure is usually performed by providing a cover sheet on the photosensitive layer as necessary and using a negative or positive pattern mask by a contact method or a projection method. When the unexposed portion is developed with a developing solution, a resist image corresponding to the pattern is obtained. As the developing solution, a developing solution comprising an organic solvent such as perchloroethylene and trichloroethane, an alkaline developing solution containing a basic compound, and the like can be used. Examples of the basic compound of the alkali developer include inorganic bases such as potassium carbonate, sodium carbonate, potassium hydrogen carbonate, sodium hydrogen carbonate, sodium silicate, and sodium phosphate; trimethylamine, triethylamine, ethanolamine, diethanolamine,
Organic bases such as triethanolamine, morpholine and pyridine are exemplified. Note that the alkali developer may contain an organic solvent such as ethylene glycol monobutyl ether.

When a circuit pattern is formed, after forming a resist image, the resist image is treated with a plating solution or an etching solution, and the resist image is peeled off with a strong alkaline aqueous solution such as sodium hydroxide or an organic solvent such as methylene chloride. .

[Effect of the Invention] Since the photopolymerizable composition of the present invention contains the hydroxybenzoic acid amide compound, it exhibits stable photosensitivity and is excellent in reproducibility. Therefore, the photopolymerizable composition of the present invention is useful as a photoresist for producing a printed wiring board, a circuit board, a metal relief image, a printing plate, and the like.

[Examples] The present invention will be specifically described with reference to examples.

Examples 1 and 2 and Comparative Example The following ingredients were mixed with 0 g of anilide salicylate (comparative example) and 2 g.
(Example 1) and 3 g (Example 2) were mixed to obtain a photopolymerizable composition.

Methacrylic acid 12% by weight, acrylic acid 8% by weight, methyl methacrylate 45% by weight, 2-phenoxyethyl acrylate
35% by weight of copolymer 50 g trimethylolpropane triacrylate 15 g nonaethylene glycol dimethacrylate 10 g 2,4-dimethylthioxanthone 0.8 g ethyl p-dimethylaminobenzoate 3 g 2- (o-chlorophenyl) -3, 4-Diphenylimidazolyl dimer 1.5 g Leuco crystal violet 0.3 g Diamond green GH 0.03 g Methyl ethyl ketone 70 g Tetrahydrofuran 10 g The photopolymerizable compositions obtained in Comparative Example, Example 1 and Example 2 were each formed into a film thickness of 25 μm. Was applied to the polyethylene terephthalate film support of Example 1 and dried at a temperature of 75 ° C. to obtain a photosensitive film. The thickness of the photosensitive layer was 50 μm. The photosensitive film was laminated on a polished copper-clad laminate using a rubber roller heated to 100 ° C. A 21-step Stopher step tablet was placed on a photosensitive film, and irradiated with a ² Kw ultra-high pressure mercury lamp from a distance of 70 cm so that an integrated light amount was 30 mJ / cm ^2, and cured, and a polyethylene terephthalate film support was peeled off. Then, it was developed with a 1% sodium carbonate aqueous solution at 30 ° C., and a resin relief image was obtained on the copper clad laminate. Then, the number of steps corresponding to the Stoffer step tablet from which the unexposed portion of the photopolymerizable composition was removed by development was used as an index of sensitivity.

The above operation was repeated to examine the fluctuation range of sensitivity. When the change in sensitivity after storage for 6 months was examined, the results shown in the table were obtained.

As shown in the table, the photopolymerizable compositions of Comparative Examples have large fluctuations in sensitivity and changes with time, whereas the photopolymerizable compositions of Examples 1 and 2 have stable sensitivity over time. .

Claims (1)

(57) [Claims] 1. A thermoplastic polymer binder, (2) an addition polymerizable compound which is liquid or solid at room temperature and normal pressure, (3) a photopolymerization initiator, and (4) a general formula (I). (Wherein R ₁ represents a hydrogen atom, an alkyl group, an aryl group or a halogen atom which may be substituted, and R ₂ represents an alkyl group or an aryl group which may be substituted). A photopolymerizable composition containing a compound.