JPH0710913A - Photopolymerizable composition - Google Patents

Abstract

PURPOSE:To improve sensitivity, solvent solubility, and storage stability by incorporating a specific photopolymerization initiator system into an addition- polymerizable compound having an ethylenically unsaturated bond. CONSTITUTION:A photopolymerization initiator system which comprises 0.05-20 pts.wt. sensitizer represented by formula I (wherein R<1> is a 2-6C alkyl and A is a naphthalene ring or a benzene ring which may be substituted with Cl or methyl) and 0.5-80 pts.wt. imidazole compound represented by formula II (wherein X<1> is COOR<2> or Cl; X<2> is H or Cl; and R<2> is a 2-4C alkyl) and may contain up to 50 pts.wt. heterocyclic thiol represented by formula III (wherein Y is S, O, or NH) is incorporated into 100 pts.wt. addition-polymerizable compound having at least one ethylenically unsaturated bond.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a photopolymerizable composition. In particular, the present invention relates to a photopolymerizable composition which not only exhibits extremely high sensitivity to light in the visible region but is advantageous in production.

[0002]

2. Description of the Related Art Conventionally, many image forming methods utilizing a photopolymerization system are known. For example, a photopolymerizable composition comprising a compound containing an addition-polymerizable ethylenic double bond, a photopolymerization initiator, and an organic polymer binder optionally used is prepared, and the photopolymerizable composition is supported. A photosensitive material having a layer of the photopolymerizable composition applied on the body is prepared, and the desired image is imagewise exposed to polymerize and cure the exposed portion, and the unexposed portion is dissolved and removed to form a cured relief image. In the method described above, a layer of a photopolymerizable composition is provided between two supports, at least one of which is transparent in the above-mentioned light-sensitive material, and the transparent support side is image-exposed to cause a change in adhesive strength due to light. After that, there is a method of forming an image by peeling the support, and an image forming method utilizing the change of toner adherability of the photopolymerizable composition layer due to light. Conventionally, benzoin, benzoin alkyl ether, benzyl ketal, benzophenone, anthraquinone, benzyl, Michler's ketone, etc. have been used as the photopolymerization initiator of the photopolymerizable composition applied to these methods.

However, these photopolymerization initiators are
Compared with the ability to initiate photopolymerization for light in the ultraviolet region below 00 nm, it is significantly lower than that for light in the visible light region above 400 nm, thus limiting the range of application of photopolymerizable compositions containing them. In recent years, with the development of image forming technology, there has been a strong demand for photopolymers having a high sensitivity to light rays in the visible region. For example, it is a light-sensitive material suitable for non-contact type projection exposure plate making, laser plate making by visible light laser, and the like. Among these technologies, especially the 488 of argon ion laser
The plate-making method using an oscillation beam of nm is considered to be one of the most promising techniques in the future.

Several proposals have hitherto been made for photopolymerization compositions containing a photopolymerization initiation system capable of being sensitive to light rays in the visible light region. For example, a system of hexaarylbiimidazole, a radical generator and a dye (Japanese Patent Publication No.
-37377), a system of hexaarylbiimidazole and (p-dialkylaminobenzylidene) ketone (JP-A-47-2528, JP-A-54-155292).
No. 6, JP-A-56-166154), cyclic cis-
Systems of α-dicarbonyl compounds and dyes (JP-A-48-84)
183), a system of substituted triazine and merocyanine dye (JP-A-54-151024), a system of ketocoumarin and an activator (JP-A-52-112681, JP-A-5-121681).
No. 8-15503, JP-A-60-88005), a system of substituted triazine and a sensitizer (JP-A-58-29).
No. 803, No. 40302), biimidazole,
Styrene derivative-thiol system (JP-A-59-5640)
3), a system of an organic peroxide and a dye (JP-A-59-1).
No. 40203, No. 189340), and s-triazine compounds having a trihalomethyl group and a styryl group (Japanese Patent Publication No. 59-1281) are proposed.

However, although these conventional techniques are certainly effective for visible light, they have the drawback of not being very sensitive. In view of such circumstances, a part of the present invention has previously proposed a high-sensitivity sensitizer having a julolidyl group and a heterocyclic structure (JP-A-2-69). The sensitizer gives excellent sensitivity in a system combined with, for example, biimidazoles.

[0006]

However, as a result of intensive investigations by the present inventors to further advance the photopolymerization initiation system, the present inventors have found that the photosensitizer having a specific structure and the biimidazole compound As a result of selecting and combining those having a specific structure among them, it has been found that all of the characteristics from a practical point of view, specifically, high sensitivity characteristics, solubility in a solvent, thermal stability, etc. are provided. Reached

That is, an object of the present invention is to provide a photopolymerizable composition which is excellent in high-sensitivity characteristics and solubility and has good storage stability.

[0008]

Accordingly, the object of the present invention is to provide a photopolymerizable composition containing a photopolymerization initiation system and an addition-polymerizable compound having at least one ethylenically unsaturated double bond. The photopolymerization initiation system comprises (a) a sensitizer represented by the following general formula [I]

[0009]

[Chemical 4]

(In the formula, R ¹ represents an alkyl group having 2 to 6 carbon atoms, A represents a naphthalene ring, or a benzene ring which may be substituted with a chlorine atom or a methyl group) and (b). Biimidazole compound represented by the following general formula [II]

[0011]

[Chemical 5]

(Where X ¹ Represents a -COOR ² residue or a chlorine atom, and X ² Represents a hydrogen atom or a chlorine atom, and R ² represents an alkyl group having 2 to 4 carbon atoms. Is easily achieved by a photopolymerizable composition characterized by containing Hereinafter, the present invention will be described in detail.

The addition-polymerizable compound having at least one ethylenically unsaturated double bond contained as the first essential component in the photopolymerizable composition of the present invention (hereinafter abbreviated as "ethylenic compound") is When the photopolymerizable composition is irradiated with actinic rays, it is a compound having an ethylenically unsaturated double bond that undergoes addition polymerization by the action of the photopolymerization initiation system that is the second essential component and cures. For example, it is a monomer having the above double bond or a polymer having an ethylenically unsaturated double bond in the side chain or main chain. Incidentally, the meaning of the monomer in the present invention is a concept facing a so-called polymer substance, and therefore includes not only a narrowly defined monomer but also a dimer, a trimer and an oligomer. is there.

Examples of the monomer having an ethylenically unsaturated bond include unsaturated carboxylic acid, ester of aliphatic polyhydroxy compound and unsaturated carboxylic acid; ester of aromatic polyhydroxy compound and unsaturated carboxylic acid; Examples thereof include esters obtained by an esterification reaction of a saturated carboxylic acid with a polyvalent carboxylic acid and the above-mentioned aliphatic polyhydroxy compound, polyvalent hydroxy compound such as aromatic polyhydroxy compound, and the like.

The ester of the aliphatic polyhydroxy compound and the unsaturated carboxylic acid is not limited, but specific examples thereof include ethylene glycol diacrylate, triethylene glycol diacrylate, trimethylolpropane triacrylate, trimethylolethane triacrylate. Acrylic esters such as pentaerythritol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, and gloserol acrylate. Methacrylic acid ester replaced with methacrylate, itaconic acid ester similarly replaced with itaconate Crotonate is maleic acid ester, and was replaced with crotonic acid ester or maleate was replaced.

Examples of the ester of an aromatic polyhydroxy compound and an unsaturated carboxylic acid include hydroquinone diacrylate, hydroquinone dimethacrylate, resorcin diacrylate, resorcin dimethacrylate and pyrogallol triacrylate. The ester obtained by the esterification reaction of an unsaturated carboxylic acid with a polyvalent carboxylic acid or a polyvalent hydroxy compound is not necessarily a single substance, but representative specific examples include acrylic acid, phthalic acid and ethylene glycol. Examples thereof include condensates, 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.

In addition to the above ester (meth) acrylates, there are so-called urethane (meth) acrylates and epoxy (meth) acrylates. The former can be prepared by an addition reaction between a polyvalent isocyanate and hydroxyacrylic esters, and the latter can be prepared by an addition reaction between a polyvalent epoxy compound and hydroxyacrylic esters.

Other examples of the ethylenic compound used in the present invention include acrylamides such as ethylenebisacrylamide; allyl esters such as diallyl phthalate;
Vinyl group-containing compounds such as divinyl phthalate are useful. The polymer having an ethylenically unsaturated bond in the main chain described above is, for example, a polyester obtained by a polycondensation reaction of an unsaturated divalent carboxylic acid and a dihydroxy compound,
There are polyamides and the like obtained by polycondensation reaction of unsaturated divalent carboxylic acid and diamine. The polymer having an ethylenically unsaturated bond in the side chain is a condensation polymer of a dicarboxylic acid having an unsaturated bond in the side chain, such as itaconic acid, propylidene succinic acid, ethylidene malonic acid, etc. and a dihydroxy or diamine compound. . Further, a polymer having a functional group having a reactive activity such as a hydroxy group or a methyl halide group in its side chain, for example, polyvinyl alcohol, poly (2-hydroxyethyl methacrylate), polyepichlorohydrin, etc. and acrylic acid, methacrylic acid, crotonic acid, etc. Polymers obtained by the macromolecular reaction with the unsaturated carboxylic acid can also be suitably used.

Of the above-mentioned ethylenic compounds, acrylic acid ester or methacrylic acid ester monomers are particularly preferably used. Next, the photopolymerization initiation system which is the second essential component of the photopolymerizable composition of the present invention will be described. The photopolymerization initiation system of the present invention is composed of a combination of two components, and the first component thereof is the sensitizer represented by the above general formula [I] represented by (a) in the present invention. The basic structure of the sensitizer of the present invention is already known as described above. While these sensitizers have the property of providing high sensitivity, their solubilities in solvents are not always sufficient. However, as a result of further studies, it was found that when a sensitizer having a specific substituent and a specific component (b) biimidazole described later are combined, sufficient solubility can be secured. The sensitizer having the specific substituent means that in the general formula [I], R ¹ has 2 to 6 carbon atoms.
It is a sensitizer having one alkyl group. R ¹ may have a straight chain or a side chain.

Typical examples of the sensitizer represented by the general formula [I] will be given below, but the compounds used in the present invention are not limited to these specific examples unless the gist thereof is exceeded.

[0021]

[Table 1]

The sensitizer represented by the general formula [I] described above can be prepared according to the method described in the above document. Next, the specific biimidazole compound represented by the general formula [II] represented by (b) in the present invention will be described. Some of the imidazole compounds of the present invention are already known compounds (JP-A-3-191353, JP-A-4).
-306659 and Japanese Patent Laid-Open No. 4-304456). The biimidazole compound of the present invention is 4,
The phenyl group at the 4 ', 5, 5'position is a carboalkoxy group,
That is, it includes one substituted with a group of —COOR ² . R ² represents an alkyl group having 2 to 4 carbon atoms,
It may be linear or may have a side chain. When the carbon number is 5 or more, crystallization of biimidazole may be difficult and purification may be complicated. Further, the biimidazole compound of the present invention includes those substituted with the chlorine atom of the phenyl group at the 4,4 ', 5,5' position.

Typical examples of the biimidazole compound represented by the general formula [II] are shown below, but the compounds used in the present invention are not limited to these specific examples unless the gist thereof is exceeded.

[0024]

TABLE 2 [Compound Example] _{b-1│X 1: -COOC 2 H} 5, X 2: a hydrogen atom _{b-2│X 1: -COOC 3 H} 7, X 2: a hydrogen atom b-3│X _{1 : -COOC 4 H 9, X 2} : a hydrogen atom b-4│X _1: chlorine atom, X _2: a chlorine atom b-5│X _1: chlorine atom, X _2: a hydrogen atom

The above-mentioned biimidazole compound represented by the general formula [II] can be easily prepared by a conventional method, for example, from the corresponding benzyl compound or benzaldehyde compound. As described above, the photopolymerization initiation system of the present invention is preferably a system in which the above-mentioned two components (a) and (b) are combined. However, if desired, the heterocyclic thiol compound represented by the general formula [III] is further used. Can be added. Specifically, this is a 2-mercaptobenzothiazole, 2
-Mercaptobenzoxazole, 2-mercaptobenzimidazole. The addition of these compounds often leads to advantageous sensitivity and other properties.

The above-mentioned photopolymerization initiating system component is preferably used in an amount of 0.05 to 20 parts by weight, more preferably 0.1 to 15 parts by weight of the sensitizer (a) per 100 parts by weight of the ethylenic compound. And the biimidazole compound (b) is 0.5 to 8
It is 0 part by weight, more preferably 1 to 50 parts by weight. The heterocyclic thiol optionally used can be preferably used in an amount of 50 parts by weight or less based on the above-mentioned equivalent amount.

In the photopolymerizable composition of the present invention, in addition to the above-mentioned components, an organic polymer substance may be further added as a binder in order to modify the composition and improve the physical properties after photocuring. it can. The binder may be appropriately selected depending on the improvement purpose such as compatibility, film forming property, developability, and adhesiveness. Specifically, for example, to improve the water-based developability, acrylic acid copolymer, methacrylic acid copolymer, itaconic acid copolymer, partially esterified maleic acid copolymer, acidic cellulose modified product having a carboxyl group in the side chain, Examples include polyethylene oxide and polyvinylpyrrolidone. To improve the film strength and adhesion, a polyether of epichlorohydrin and bisphenol A; soluble nylon; polyalkylmethacrylate such as polymethylmethacrylate or alkylpolyacrylate; alkylmethacrylate and acrylonitrile, acrylic acid, methacrylic acid , Copolymers with vinyl chloride, vinylidene chloride, styrene, etc .; Copolymers with acrylonitrile and vinyl chloride, vinylidene chloride; Vinylidene chloride, chlorinated polyolefins, copolymers with vinyl chloride and vinyl acetate; Polyvinyl acetate Copolymer of acrylonitrile and styrene; Copolymer of acrylonitrile, butadiene and styrene; Polyvinyl alkyl ether; Polyvinyl alkyl ketone; Polystyrene; Polyamide; Polyurethane; Polyethylene terephthalate isophthalate Mention may be made of acetyl cellulose and polyvinyl butyral, and the like. The weight ratio of these binders to the ethylenic compound is preferably 500% or less, more preferably 200% or less.
It can be added and mixed in the range of not more than%.

The photopolymerizable composition of the present invention may further contain a thermal polymerization inhibitor, a colorant, a plasticizer, a surface protective agent, a smoothing agent, if necessary.
Coating aids and other additives can be added. Examples of the thermal polymerization inhibitor include hydroquinone, p-methoxyphenol, pyrogallol, catechol, 2,6-di-
There are t-butyl-p-cresol, β-naphthol, and the like. Examples of the colorant include phthalocyanine pigments, azo pigments, carbon black, pigments such as titanium oxide, ethyl violet, crystal violet, azo dyes, anthraquinone dyes. , There are cyanine dyes. When the binder is used, the thermal polymerization inhibitor and the colorant are added in an amount of 0.01% to 3% of the thermal polymerization inhibitor and 0.1% of the colorant with respect to the total weight of the ethylenic compound and the binder.
1% to 20% is preferred.

Examples of the plasticizer include dioctyl phthalate, didodecyl phthalate, triethylene glycol dicaprylate, dimethyl glycol phthalate, tricresyl phosphate, dioctyl adipate, dibutyl sebacate, triacetyl glycerin, etc. When used, 20% or less can be added to the total weight of the ethylenic compound and the binder.

When using the photopolymerizable composition of the present invention,
The light-sensitive material can be prepared by forming the light-sensitive material without a solvent or dissolving it in a suitable solvent to form a solution, which is applied on a support and dried. Examples of the solvent include methyl ethyl ketone, cyclohexanone, butyl acetate, amyl acetate, ethyl propionate, toluene, xylene, monochlorobenzene, carbon tetrachloride, trichloroethylene,
Examples include trichloroethane, dimethylformamide, methyl cellosolve, ethyl cellosolve, tetrahydrofuran and bentoxone.

The support applied when preparing a light-sensitive material using the photopolymerizable composition of the present invention may be any of those usually used. For example, a sheet of metal such as aluminum, magnesium, copper, zinc, chromium, nickel, iron or an alloy containing them as a main component; high-quality paper, art paper,
Papers such as release paper; inorganic sheets such as glass and ceramics; polyethylene terephthalate, polyethylene, polymethylmethacrylate, vinyl chloride, vinyl chloride-vinylidene chloride copolymer, polystyrene, 6-nylon, cellulose triacetate, cellulose acetate butyrate, etc. Polymer sheets, etc.

Further, the photopolymerizable composition of the present invention is further provided with a known technique for preventing adverse effects such as sensitivity decrease and storage stability deterioration due to oxygen, for example, providing a peelable transparent cover sheet on the photosensitive layer. Wax-like substance with low oxygen permeability,
It is also possible to provide a coating layer made of a water-soluble polymer or the like.
The exposure light source that can be applied to the composition of the present invention is not particularly limited, but carbon arc, high pressure mercury lamp, xenon lamp, metal halide lamp, fluorescent lamp, tungsten lamp, helium cadmium laser, argon ion laser and the like visible light of 400 nm or more. A general-purpose light source including can be used more suitably.

[0033]

EXAMPLES The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples as long as the gist thereof is not exceeded. In addition,
The following symbols used in the comparative examples indicate the corresponding compounds.

[0034]

[Chemical 6]

[Examples 1 to 8 and Comparative Examples 1 to 3] Methyl methacrylate / methacrylic acid copolymer (weight average molecular weight 4
5,000, copolymerization ratio 85/15) 5 g, trimethylolpropane triacrylate 5 g, 2-mercaptobenzthiazole 1 g, Victoria Pure Blue BOH60
mg was completely dissolved in 50 g of methyl ethyl ketone.
Then, 200 mg of the sensitizer (a) and 1.2 g of biimidazole (b) shown in Table 1 were added, and the mixture was stirred and dissolved at 25 ° C. to obtain a photosensitive solution. At that time, the criteria for determining the solubility of the components (a) and (b) were as follows.

[0036]

[Table 3] "Good" ... Total dissolution within 1 hour "Slightly bad" ... Total dissolution after a long time "Poor" ... Partially insoluble even after a long time

The sensitivity measurement with respect to the light of 488 nm was carried out by the following method. First, if a non-solution remains, the photosensitive solution obtained by the above-mentioned method is filtered off, and then a dry film thickness of 2 μm is formed on an aluminum sheet which is grained and anodized. The coating was dried for 5 minutes at 70 ° C. Then, an overcoat layer having a dry film thickness of 3 μm was provided. After exposing the obtained light-sensitive material using a diffraction spectrum irradiator (RM-23, RM-23),
Butyl cellosolve 9% by weight, sodium silicate 1% by weight
Was developed with an alkaline aqueous developing solution containing, and the amount of light required for photocuring corresponding to a light beam of 488 nm was determined, and the amount of energy was expressed as a sensitivity.

[0038]

[Table 4]

[Examples 9 to 12 and Comparative Examples 4 and 5] The light-sensitive materials prepared by the same method as in Example 1 were allowed to stand in an oven at 55 ° C for 6 days to measure the sensitivity retention rate. The photosensitive materials were prepared by using the components (a) and (b) shown in Table 2 in Example 1.
It has the same configuration except that the same amount was added. The "sensitivity retention rate (%)" used in Examples and Comparative Examples is a value calculated by the following equation.

[0040]

[Equation 1]

[0041]

[Table 5]

[0042]

INDUSTRIAL APPLICABILITY The photopolymerizable composition of the present invention is a photopolymerizable composition having high sensitivity properties, excellent solubility and storage stability, and excellent in practicality.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location G03F 7/038

Claims (2)

[Claims] 1. A photopolymerizable composition comprising an addition-polymerizable compound having at least one ethylenically unsaturated double bond and a photopolymerization initiation system, wherein the photopolymerization initiation system is (a) ] A sensitizer represented by (In the formula, R ¹ represents an alkyl group having 2 to 6 carbon atoms, and A 1
Represents a naphthalene ring or a benzene ring optionally substituted with a chlorine atom or a methyl group. ) And (b) a biimidazole compound represented by the following general formula [II]: (Where X ¹ Represents a —COOR ² group or a chlorine atom, and X ² Represents a hydrogen atom or a chlorine atom, and R ² represents an alkyl group having 2 to 4 carbon atoms. ) Is contained, The photopolymerizable composition characterized by the above-mentioned. 2. The heterocyclic thiol compound represented by the following general formula [III] is further contained in the photopolymerizable composition. (In formula, Y represents -S-, -O-, or -NH-.), The photopolymerizable composition of Claim 1 characterized by the above-mentioned.