JP2897298B2 - Photopolymerizable composition - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a photopolymerizable composition containing an improved photopolymerization initiation system, and more particularly to photopolymerization using a photopolymerization initiation system containing biimidazoles. The present invention relates to an acidic composition.

[Prior Art] Conventionally, a large number of photopolymerization initiators or photopolymerization initiator systems have been developed and applied and put to practical use. All of these have been selected and adopted in consideration of the use, purpose and required performance. A biimidazole-based initiation system is attracting attention as a useful initiation system component, since good sensitivity characteristics are usually obtained in combination with a specific sensitizer.

However, the main components of the photopolymerizable material are generally
In many cases, a polymerizable unsaturated monomer and a photopolymerization initiation system, and a polymer binder that is appropriately blended, in which case, with the increase in the composition ratio of the polymerizable unsaturated monomer, photopolymerization starts. The stable solubility of the system tends to decrease. This is because the binder has a property of taking the starting system component as a solid solution, and this is because the physical property as a solid solution decreases with the increase in the composition ratio described above, in other words, with the decrease in the composition ratio of the binder. It is seen.

Similar behavior is observed when biimidazoles are used as one component of the photoinitiating system, and deterioration of the photosensitive material due to its lack of solubility is observed.

On the other hand, some biimidazoles show an improvement in solubility due to the introduction of a substituent into their molecular structure, but the sensitivity characteristic often decreases.

The present inventors have assiduously studied and found that by introducing a specific substituent into biimidazoles, high sensitivity and stable solubility can be achieved, and have reached the present invention. That is, an object of the present invention is to provide a photopolymerizable composition including a photopolymerization initiation system having high sensitivity characteristics and excellent solubility. Thus, the object of the present invention is to
In a photopolymerizable composition comprising a polymerizable ethylenically unsaturated monomer and a photopolymerization initiation system, the photopolymerization initiation system contains a hexaarylbiimidazole and a sensitizer, and the hexaarylbiimidazole is A photopolymerizable composition characterized by being represented by the general formula [I].

(Wherein, Ar ₁ is an aryl group in which the o-position is substituted with a halogen atom, Ar ₂ and Ar _{3 each} represent an aryl group, at least one of which is a carboalkoxy containing a C _{1 to} C ₁₂ alkyl group. And an aryl group having at least one group as a substituent.)

 Hereinafter, the present invention will be described in more detail.

First, the polymerizable ethylenically unsaturated monomer used in the present invention is not particularly limited as long as it exhibits a chain polymerization reaction with an active free radical. In addition, the meaning of the monomer is a concept corresponding to a so-called polymer substance, and therefore, in addition to a monomer in a narrow sense, a dimer, a trimer,
It also includes oligomers.

Examples of the polymerizable ethylenically unsaturated monomer include unsaturated carboxylic acids, esters of aliphatic polyhydroxy compounds and unsaturated carboxylic acids; esters of aromatic polyhydroxy compounds and unsaturated carboxylic acids; Esters obtained by an esterification reaction between a carboxylic acid and a polyvalent carboxylic acid and a polyvalent hydroxy compound such as the above-mentioned aliphatic polyhydroxy compound and aromatic polyhydroxy compound are exemplified.

Specific examples of the ester of the aliphatic polyhydroxy compound and the unsaturated carboxylic acid include ethylene glycol diacrylate, triethylene glycol diacrylate, trimethylolpropane triacrylate, trimethylolethane triacrylate, pentaerythritol diacrylate, and pentaerythritol Acrylates such as triacrylate, pentaerythritol tetraacrylate, dipentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, and glycerol acrylate; methacrylates in which the acrylate of these exemplified compounds is replaced with methacrylate; Itaconic acid ester instead of itaconate, croton instead of crotonate There are maleic acid esters in which instead of the ester or maleate.

Examples of the ester of the aromatic polyhydroxy compound and the unsaturated carboxylic acid include hydroquinone diacrylate, hydroquinone dimethacrylate, resorcin diacrylate, resorcin dimethacrylate, and pyrogallol triacrylate.

The ester obtained by the esterification reaction of the unsaturated carboxylic acid with the polycarboxylic acid and the polyhydroxy compound is not necessarily a single substance, but typical examples include acrylic acid, phthalic acid, and ethylene glycol. Condensates of acrylic acid, maleic acid and diethylene glycol, condensates of methacrylic acid, terephthalic acid and pentaerythritol, condensates of acrylic acid, adipic acid, butanediol and glycerin.

Other examples of the ethylenically unsaturated monomer used in the present invention include urethane acrylates such as an addition product of triene diisocyanate and hydroxyethyl acrylate; and addition products of an addition reaction product of diepoxy compound and hydroxyethyl acrylate. Epoxy acrylates;
Acrylamides such as ethylenebisacrylamide; allyl esters such as diallyl phthalate; and vinyl group-containing compounds such as divinyl phthalate are useful.

Of these, acrylate or methacrylate monomers are particularly useful.

Next, the hexaarylbiimidazole of the present invention will be described. This is a compound having a structure of the following general formula in which two imidazoles are also connected by one covalent bond, also called a 2,4,5-triarylimidazolyl dimer.

In the present invention, various isomers of the above compounds can be used.

Ar ₁ in the above general formula is an aryl group having a halogen substituent at the o-position, particularly preferably an o-chlorophenyl or o-bromophenyl group. Ar ₂ and Ar ₃ each represent an aryl group having at least one specific substituent. Particular substituents include C ₁ -C
It is a carboalkoxy group having ₁₂ alkyl groups.

Representative biimidazoles that have been conventionally used are those in which, in the above general formula, Ar ₁ is o-chlorophenyl, Ar ₂ , Ar ₃
Has a structure of a phenyl group, but has a satisfactory sensitivity but is not sufficiently soluble in acrylate monomers and the like. However, we have found that by introducing the above-mentioned specific substituents as Ar ₂ and Ar ₃ in the general formula, the dissolution stability can be greatly improved while maintaining high sensitivity.

To specifically illustrate the biimidazole of the present invention, for example,
2,2'-bis (o-bromophenyl) -4,4 ', 5,5'-tetra (p-carbomethoxyphenyl) biimidazole,
2,2'-bis (o-bromophenyl) -4,4 ', 5,5'-tetra (p-carbo-n-butoxyphenyl) biimidazole, 2,2'-bis (o-chlorophenyl)- 4,4 ′, 5,
5'-tetra (p-carbo-n-octoxyphenyl) biimidazole and the like can be mentioned.

Of these, one or more kinds of biimidazoles can be used in combination with other kinds of biimidazoles, if necessary. These biimidazoles are described, for example, in Bull.
c.Japan, 33, 565 (1960) and J.org.Chem., 36 [16] 22
62 (1971).

Next, the sensitizer of the present invention will be described. The sensitizer in the present invention means a compound capable of generating an active radical upon irradiation with light when coexisting with the above-mentioned biimidazoles.

Examples of representative enhancers include, for example, U.S. Pat.
No. 479,185, a triphenylmethane leuco dye such as leuco crystal violet or leucomalachite green, a photoreducing dye such as erythrosine or eosin Y, U.S. Pat.No. 3,549,367, U.S. Pat. Aminophenyl ketones such as Michler's ketone and aminostyryl ketone disclosed in US Pat. No. 3,652,275, etc .;
-Diketones, imidanones found in JP-A-54-155292, aminostyrene derivatives and aminophenylbutadiene derivatives disclosed in JP-A-59-56403.

The main constituents of the photopolymerizable composition of the present invention have been described in detail above, but their preferred use ratio is represented by the general formula [I] based on 100 parts by weight of the polymerizable ethylenically unsaturated monomer. The hexaarylbiimidazole shown is preferably 0.1 to 60 parts by weight, particularly preferably 0.5 to 40 parts by weight,
The sensitizer is preferably 0.01 to 20 parts by weight, particularly preferably 0.1 to 20 parts by weight.
It is in the range of 05 to 10 parts by weight.

The photopolymerizable composition of the present invention, in addition to the above components,
Other substances can be further added and mixed depending on the purpose of use.

For example, when a film-forming ability or a viscosity adjusting ability is required, an organic polymer substance may be added as a binder. Specific examples thereof include, for example, homo- or copolymers of (meth) acrylic acid, their esterified products, maleic acid, acrylonitrile, styrene, vinyl acetate, vinyl chloride, etc., polyethylene oxide, polyvinylpyrrolidone, polyamide, polyurethane , Polyethylene terephthalate isophthalate, acetyl cellulose or polyvinyl butyral. These binders are preferably added and mixed in an amount of preferably 200 parts by weight or less, particularly preferably 100 parts by weight or less, based on 100 parts by weight of the ethylenically unsaturated monomer.

In addition, hydroquinone, p-methoxyphenol,
2,6-di-tert-butyl-p-cresol thermal polymerization inhibitor; coloring agent comprising an organic or inorganic dye / pigment; dioctyl phthalate, didodecyl phthalate, tricresyl phosphate, dioctyl adipate, triethylene glycol Plasticizers such as dicaprylate, sensitizers such as tertiary amines and thiols, and other additives such as dye precursors can also be added.

Preferred amounts of the various additives described above are 2 parts by weight or less of a thermal polymerization inhibitor and 100 parts by weight of an unsaturated monomer,
The range is 0 part by weight or less, the plasticizer 40 parts by weight or less, and the dye precursor 30 parts by weight or less.

The form of the photosensitive material produced by using the present composition can be appropriately selected according to the purpose of use. For example, a solvent-free or diluted with an appropriate solvent, applied onto a sheet, for example, a polymer sheet, paper, or a metal sheet, dried and, if necessary, an overcoat layer or a polymer sheet layer for blocking oxygen is further formed on the upper layer. Various forms such as a form provided, a form in which the present composition is encapsulated in microcapsules and applied on a sheet, and a form in which a liquid photosensitive resin is used as it is can be selected.

The exposure light source applicable to the composition of the present invention is not particularly limited, but includes, for example, carbon arc, high-pressure mercury lamp, xenon lamp, metal halide lamp, fluorescent lamp, tungsten lamp, halogen lamp, helium cadmium laser, argon ion laser, and the like. It can be used particularly preferably.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples as long as the gist of the present invention is not exceeded.

Examples 1-2 and Comparative Examples 1-9 The following evaluation methods were used to evaluate the solubility and sensitivity of various biimidazoles.

A. Solubility Trimethylolpropane triacrylate (TMPT)
A) is prepared by preparing 95 parts by weight of a polymerizable composition stock solution consisting of 95 parts by weight and 5 parts by weight of a methyl methacrylate / methacrylic acid copolymer (copolymerization ratio: 90/10, molecular weight: 30,000). , A biimidazole sample equivalent to 5% by weight is added thereto, dissolved and mixed at 80 ° C., and then left at room temperature for a long time. The dissolution stability is ranked in the following four stages.

a. Good …… Stable dissolution retention for a long time b. Slightly good… Precipitated within 2 months even once dissolved c. Slightly poor …… Precipitated within 1 week even once dissolved d. Poor …… Initial More partial dissolution only B. Sensitivity Sensitizer 2- in the same composition as the above polymerizable composition stock solution
0.2% by weight of (p-diethylaminostyryl) -B-naphthothiazole and 2-methylcaptobenzothiazole 2
After dissolving and mixing the weight%, a predetermined amount is separated. To this, the same amount of 2% by weight of the same biimidazole sample as above was added and dissolved by heating. This sample composition is applied to an aluminum sheet subjected to a graining treatment so as to have a thickness of 150 μm, and the surface thereof is covered with a PET film having a thickness of 12 μm.
A step tablet is superimposed on this and irradiated with xenon light through a glass filter Y-42 (manufactured by Toshiba Glass Co., Ltd.). After exposure, the PET film was peeled off and removed, and the undeveloped portion of the photosensitive layer was washed away with acetone, and the relative sensitivity was determined from the obtained number of curing steps. The evaluation of the relative sensitivity was performed based on Example 1.

Table 1 shows the above evaluation results. In the table, the aryl groups Ar ₁ , Ar ₂ and Ar ₃ of biimidazole are the same as those of the general formula [I].

[Effects of the Invention] As described above, according to the present invention, a photopolymerizable composition having high sensitivity and excellent dissolution stability can be obtained.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-188943 (JP, A) JP-A-49-54018 (JP, A) JP-A-60-202437 (JP, A) JP-A-59-1984 230003 (JP, A) JP-A-62-174202 (JP, A) JP-B-63-2099 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03F 7 / 028-7 / 031 C08F 2/50

Claims (1)

(57) [Claims] 1. A photopolymerizable composition containing a polymerizable ethylenically unsaturated monomer and a photopolymerization initiation system, wherein the photopolymerization initiation system contains hexaarylbiimidazole and a sensitizer, A photopolymerizable composition, wherein the hexaarylbiimidazole is represented by the following general formula [I]. (Wherein, Ar ₁ is an aryl group in which the o-position is substituted with a halogen atom, Ar ₂ and Ar _{3 each} represent an aryl group, at least one of which is a carboalkoxy containing a C _{1 to} C ₁₂ alkyl group. An aryl group having at least one group as a substituent is shown.)