JPH07281434A - Photopolymerizable composition - Google Patents

Abstract

PURPOSE:To attain high sensitivity to visible light, especially light of long wavelength and to ensure superior property of forming a visible image by development by incorporating a specified sensitizer and a specified titanocene compd. into a photopolymn. initiation system. CONSTITUTION:This photopolymerizable compsn. contains at least an addition- polymerizable compd. and a photopolymn. initiation system. The addition- polymerizable compd. has one or more ethylenically unsatd. double bonds and the photopolymn. initiation system contains a sensitizer represented by the formula and a titanocene compd. capable of generating active radicals when irradiated with light under coexistence of the sensitizer. In the formula, each of R<1>-R<3> is H, halogen, alkyl, aryl, aralkyl, etc., R<4> is H, alkyl, aryl, aralkyl, etc., R<5> is H, alkyl, aryl, aralkyl, etc., A is an optronally substd. mono- or bicyclic hydrocarbon ring or an optionally substd. hetero ring and each of X<1> and X<2> is halogen, alkyl, aryl, aralkyl, etc.

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 exhibits extremely high sensitivity to light rays in the visible region and is excellent in visible image development.

[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. And a layer of a photopolymerizable composition is provided between two supports in which at least one of the above-mentioned light-sensitive materials is transparent, and the transparent support side is imagewise 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 adhesion of the photopolymerizable composition layer due to light. Conventionally, benzoyl, 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 have a photopolymerization initiation ability of 4 nm or less in the ultraviolet region of 400 nm or less.
It is significantly lower for light in the visible region above 00 nm and thus has limited the range of applications of photopolymerizable compositions containing them.

In recent years, with the development of image forming technology, there has been a strong demand for a photopolymer having a high adaptability 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 techniques, the plate making method using an oscillation beam of visible light of an argon ion laser is considered to be one of the most promising techniques in the future.

Several proposals have hitherto been made for a photopolymerizable composition containing a photopolymerization initiation system which is 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.
5-37377), a system of hexaarylbiimidazole and (p-dialkylaminobenzylidene) ketone (JP-A-47-2528, JP-A-54-155292).
Each of the above publications), a system of a cyclic cis-α-dicarbonyl compound and a dye (JP-A-48-84183), a system of a substituted triazine and a merocyanine dye (JP-A-54-151024).
No.), a system of ketocoumarin and an activator (JP-A-52-1).
12681, JP-A-58-15503, JP-A-60
-88005), a system of substituted triazine and a sensitizer (JP-A-58-29803, JP-A-58-40302).
Each of the above publications), biimidazole, a styrene derivative, a thiol system (JP-A-59-56403), an organic peroxide-dye system (JP-A-59-140203, JP-A-59-140203).
No. 9-189340), systems using titanocene as a photopolymerization initiation system (JP-A-59-152396, JP-A-61-151197, JP-A-63-10602, JP-A-63-41484). JP-A-2-291, JP-A-3-12403, JP-A-3-20293, and JP-A-3
No. 27393, JP-A-3-52050), a system in which a titanocene, a xanthene dye, and an addition-polymerizable ethylenic saturated double bond-containing compound having an amino group or a urethane group are combined (JP-A-4-221958, JP-A-4-219756), systems of titanocene and 3-ketocoumarin dyes (JP-A-63-221110), and the like.

[0005]

However, although these prior arts are certainly effective for visible light, they have the drawback that they are not very sensitive and still inadequate from a practical point of view. It was

[0006]

Means for Solving the Problems As a result of intensive investigations by the present inventors to overcome such difficulties and obtain an excellent photopolymerizable composition, the present inventors have found that at least a compound capable of addition polymerization and a photopolymerization initiation system are included. A photopolymerizable composition, wherein the addition-polymerizable compound has at least one ethylenically unsaturated double bond, and the photopolymerization initiation system has a sensitizer having a specific skeleton; The present inventors have found that the presence of at least one titanocene compound capable of generating an active radical upon irradiation with light in the coexistence with the sensitizer enhances sensitivity and practicality, and has reached the present invention.

That is, it is an object of the present invention to provide a photopolymerizable composition which is more sensitive to long wavelength light such as visible light. Another object of the present invention is, for example, in the case of laser plate making with a YAG laser or an argon ion laser, a higher speed plate making operation using a laser having a lower output, for example, a YAG laser using a semiconductor laser or an air-cooled argon laser. It is to provide a photopolymerizable composition that enables it.

Another object of the present invention is to provide a photopolymerizable composition which enables a plate making operation which is extremely advantageous in terms of cost and time. Therefore, the object of the present invention is to
A photopolymerizable composition comprising at least an addition-polymerizable compound and a photopolymerization initiation system, wherein the addition-polymerizable compound has at least one ethylenically unsaturated double bond,
The photopolymerization initiation system is (a) a sensitizer represented by the following general formula [I] and

[0009]

[Chemical 2]

(In the formula, R ^{1 to} R ³ are each a hydrogen atom, a halogen atom, an alkyl group, an aryl group, an aralkyl group, an acyl group, an alkoxycarbonyl group, a substituted or unsubstituted hydrocarbon ring residue, a substituted or unsubstituted hydrocarbon ring residue, Represents an unsubstituted heterocyclic residue or —SO ₃ —R ⁵ , and R ⁴ represents a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, a cyano group, a substituted or unsubstituted hydrocarbon ring residue or a substituted or unsubstituted Represents a substituted heterocyclic residue, R ⁵ represents a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, an alkali metal atom or a quaternary ammonium group, and ring A represents a substituted or unsubstituted 1
To a dinuclear hydrocarbon ring or a substituted or unsubstituted heterocycle, wherein X ¹ and X ² are each a halogen atom, an alkyl group, an aryl group, an aralkyl group, a substituted or unsubstituted hydrocarbon ring residue or a substituted group. Or represents an unsubstituted heterocyclic residue. )

(B) A photopolymerizable composition characterized by containing a titanocene compound capable of generating an active radical upon irradiation with light in the presence of the sensitizer. The present invention will be described in detail below. The addition-polymerizable compound having at least one ethylenically unsaturated double bond (hereinafter abbreviated as “ethylenic compound”) contained as the first essential component in the photopolymerizable composition of the present invention means photopolymerization. When the photosensitive composition is irradiated with actinic rays, it is a compound having an ethylenically unsaturated double bond that undergoes addition polymerization by the action of a photopolymerization initiation system that is a second essential component and is cured, 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 glycerol acrylate. Methacrylic acid ester replaced, 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.

Other examples of the ethylenic compound used in the present invention include acrylamides such as ethylenebisacrylamide; allyl esters such as diallyl phthalate; and vinyl group-containing compounds such as divinylphthalate. The above-mentioned polymer having an ethylenically unsaturated bond in the main chain is, for example, polyester obtained by polycondensation reaction of unsaturated divalent carboxylic acid and dihydroxy compound, polycondensation reaction of unsaturated divalent carboxylic acid and diamine. And the like. The polymer having an ethylenically unsaturated bond in the side chain is a divalent carboxylic acid having an unsaturated bond in the side chain, for example itaconic acid, propylidene succinic acid,
There is a condensation polymer of ethylidene malonic acid and the like 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.

Among the above-mentioned ethylenic compounds, acrylic acid ester or methacrylic acid ester monomers can be particularly preferably used. Next, the photopolymerization initiation system which is the second essential component of the photopolymerization composition of the present invention will be described. The photopolymerization initiation system of the present invention is composed of a combination of two kinds of components, and the first component thereof is the compound represented by the above general formula [I] represented as (a) in the present invention. These sensitizers include, but are not limited to, for example, after condensation of a corresponding imidazole derivative and a pyrrole derivative as shown in the following reaction formulas (1) to (3),

[0017]

[Chemical 3] U.S. Pat. No. 4,774,339, J. H. Boyer
et al, Heroatom Chemistr
y, Vol. 1,5,389 (1990) and borated [formula (4)] and synthesized.

R¹~ R^Five, X¹And X²Is an alkyl group
When it represents, it preferably has 1 to 6 carbon atoms, and
It is particularly preferable that the prime number is 1 to 3, and even if it is a straight chain
It may have a side chain. R¹~ R³Is an aralkyl group,
When representing an acyl group or an alkoxycarbonyl group, and
R^FourAnd R^FiveRepresents a aralkyl group, the carbon
The number of carbon atoms on the chain side is particularly preferably 1 to 3. R¹
~ R³, X¹And X ²Is a halogen atom,
Generally, it is preferably a bromine atom or a chlorine atom,
R^FiveWhen represents an alkali metal atom, it is generally
Is a thium atom, sodium atom or potassium atom
It is preferable. R¹~ R^Four, X¹And X²Carbonized water
A hydrocarbon ring is mononuclear or dinuclear when it represents a radical residue.
It is preferable that the substituent has 1 to 3 carbon atoms.
Particularly preferred is a rukyl group. Also, for heterocyclic groups
The hetero atom contained is generally a nitrogen atom or an oxygen source.
It is preferably a child or a sulfur atom.

In the present invention, the expression "ring A" means, to be exact, a ring composed of carbon atoms at the 4- and 5-positions of the imidazole ring.
Represents a substituted or unsubstituted 1- to 2-nuclear hydrocarbon ring or a substituted or unsubstituted heterocycle, and more preferably a benzene ring or a naphthalene ring. The substituents on these rings are preferably alkyl groups having 1 to 3 carbon atoms. The hetero atom contained in the heterocycle is generally preferably a nitrogen atom, an oxygen atom or a sulfur atom.

Typical examples of the sensitizer represented by the general formula [I] are shown below, but the sensitizer represented by the general formula [I] used in the present invention is not limited to these specific examples. Absent. In the following examples, R ¹ and R ³ represent a methyl group, ring A represents a benzene ring, and X ¹ and X ² represent a fluorine atom, unless otherwise specified. Compound example

[0021]

[Table 1]

In the present invention, at least one of the sensitizers described above is selected and used. The second component constituting the photoinitiating system of the present invention is a titanocene compound capable of generating an active radical when irradiated with light in the coexistence with the sensitizer represented by (b) in the present invention. The titanocene compound is not particularly limited, but for example, JP-A-59-152396 and JP-A-61-1511.
It can be appropriately selected and used from various titanocene compounds described in JP-A-97. More specifically,
Di-cyclopentadienyl-Ti-di-chloride, di-cyclopentadienyl-Ti-bis-phenyl, di-
Cyclopentadienyl-Ti-bis-2,3,4,5,
6-pentafluorophen-1-yl (hereinafter referred to as B-1), dicyclopentadienyl-Ti-bis-2,
3,5,6-Tetrafluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2,4,6-trifluorophen-1-yl, di-cyclopentadienyl-
Ti-bis-2,6-di-fluorophen-1-yl,
Di-cyclopentadienyl-Ti-bis-2,4-di-
Fluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,3,4,5,6-pentafluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2 , 3,5,6-Tetrafluorophen-1-yl, di-methylcyclopentadienyl-Ti
-Bis-2,6-difluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2,6-difluoro-3- (pyr-1-yl) -phen-1-yl (hereinafter B
-2) and the like.

The suitable amounts of the sensitizer and the titanocene compound constituting the photopolymerization initiation system used in the above-described photopolymerizable composition of the present invention are not particularly limited, but 100 parts by weight of the ethylenic compound is used. Sensitizer is 0.05 to 20
It is generally selected from the range of parts by weight, preferably 0.2 to 10 parts by weight, the titanocene compound is 0.5 to 2 parts by weight.
It is generally selected from the range of 0 parts by weight, preferably 0.5 to 10 parts by weight.

In the photopolymerizable composition of the present invention, for the purpose of improving sensitivity or improving storage stability, if necessary, JP-A-59-56403 and JP-A-58-298.
The activator capable of generating radicals other than titanocene described in JP-A No. 03 and an amine compound are ethylenic compounds 10
0.1 to 30 parts by weight, preferably 0.
It can be further added in a proportion of 5 to 20 parts by weight.

Particularly preferred additives include dialkylamine derivatives such as Michler's ketone and ethyl p-diethylaminobenzoate. In the photopolymerizable composition of the present invention, in addition to the above-mentioned core constituents, it is preferable to further add an organic polymer substance as a binder in order to modify the composition and improve physical properties after photocuring. Binders are compatible,
It may be appropriately selected depending on the purpose of improving the film forming property, the developing property, the adhesive property and the like. 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; polyalkyl methacrylate such as polymethylmethacrylate or alkyl polyacrylate; alkyl methacrylate and acrylonitrile, acrylic acid , Copolymers with methacrylic acid, vinyl chloride, vinylidene chloride, styrene, etc .; copolymers of acrylonitrile with vinyl chloride, vinylidene chloride; vinylidene chloride, chlorinated polyolefins, copolymers of vinyl chloride with vinyl acetate; poly Vinyl acetate; Acrylonitrile / styrene copolymer; Acrylonitrile / butadiene / styrene copolymer; Polyvinyl alkyl ether; Polyvinyl alkyl ketone; Polystyrene; Polyamide; Polyurethane; Polyethylene terephthalate Phthalate; acetyl cellulose and polyvinyl butyral, and the like. These binders can be added and mixed in a weight ratio of generally 500% or less, preferably 200% or less with respect to the ethylenic compound.

The photopolymerizable composition of the present invention may further contain a thermal polymerization inhibitor, a coloring agent, 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. ~ 2
0% is preferable.

Examples of the plasticizer include dioctyl phthalate, didodecyl phthalate, triethylene glycol dicaprylate, dimethyl glycol phthalate, tricresyl phosphate, dioctyl adipate, dibutyl sebacate, triacetyl glycerin, and the like. When used, 10% or less of the total weight of the ethylenic compound and the binder can be added.

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,
There are trichloroethane, dimethylformamide, methyl cellosolve, ethyl cellosolve, tetrahydrofuran, bentoxone, propylene glycol monomethyl ether, and the like, and one kind or a combination of two or more kinds can be used.

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, polyvinyl chloride, vinyl chloride-
Polymer sheets such as vinylidene chloride copolymer, polystyrene, 6-nylon, cellulose triacetate, and cellulose acetate butyrate are available.

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 includes carbon arc, high pressure mercury lamp, xenon lamp, metal halide lamp, fluorescent lamp, tungsten lamp, helium cadmium laser, argon ion laser, etc. visible light of 400 nm or more. A general-purpose light source can be used more suitably.

[0032]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples unless it exceeds the gist. (Synthesis of I-3) 2-Cyanomethylbenzimidazole (0.1 mol) and 2,4-dimethyl-3-ethyl-pyrrole (0.1 mol) were dissolved in 150 ml of a dichloromethane solvent, and 1 ml of concentrated hydrochloric acid aqueous solution was dissolved. 1 at 40 ° C after addition
After stirring for 1 hour and returning to room temperature, 1.5 l of petroleum ether was added, and the mixture was allowed to stand for 12 hours and precipitated, hydrochloric acid of a condensation compound of 2-cyanomethylbenzimidazole and 2,4-dimethyl-3-ethyl-pyrrole. The salt was filtered and extracted.

Next, the hydrochloride (0.024 mol) was added to 60
Triethylamine (0.113 mol) was added to 0 ml of toluene while stirring with dispersion, and then the mixture was stirred at room temperature for 15 minutes, and further boron trifluoride etherite (0.16 mol) was added.
3 mol), stirred at 80 ° C. for 15 minutes, cooled to 40 ° C., and washed the reaction solution with 100 ml of hot water three times,
After drying over magnesium sulfate and concentration by evaporation, a silica gel column (100 mesh, ethyl acetate-
I-3 was separated and purified with n-hexane 1: 9 solvent). I
The infrared absorption spectrum of -3 is shown in FIG. 1, and the absorption spectrum is shown in FIG.

Examples 1 to 4 and Comparative Examples 1 and 2 Using a whirler, a photosensitive composition coating solution having the following composition was coated on a grained and anodized aluminum sheet to a dry film thickness of 2 μm. Then, a polyvinyl alcohol aqueous solution was applied on the surface so that the dry film thickness was 3 μm to prepare a photosensitive material sample.

Next, a xenon lamp; UI-501C manufactured by USHIO INC. Was used as a sample of this photosensitive material, and the abscissa axis represents wavelength and the ordinate axis decreased logarithmically the light intensity by a spectral sensitivity measurement apparatus manufactured by Narumi. For 10 seconds. The exposed sample was developed with an aqueous solution containing 2% by weight of butyl cellosolve and 1% by weight of sodium silicate, and the minimum exposure amount required for forming a photocured image was calculated from the height of the obtained cured image. And the sensitivity. Further, the development visual image quality was visually evaluated under a commonly used yellow light. The results are shown in Table-1.

[0036]

[Table 2] [Photosensitive composition coating liquid] Methyl methacrylate / methacrylic acid copolymer: 50 parts (weight average molecular weight: 45,000, copolymerization ratio: 85/15) Trimethylolpropane triacrylate: 50 parts Methyl cellosolve: 800 parts Tetrahydrofuran ... 50 parts Sensitizer (listed in Table-1) Titanocene compound (listed in Table-1)

[0037]

[Table 3] In Table-1, [S-1] and [S-2] are respectively [S-
1] Eosin yellowish, [S-2]

[0038]

[Chemical 4] Represents

[0039]

The photopolymerizable composition of the present invention is
In particular, it has extremely high sensitivity to long-wavelength light and has excellent visual development visibility. Therefore, the composition is useful in a wide range of applications, such as lithographic, intaglio,
It can be used industrially because it can be used for making printing plates such as letterpress, photoresist for making printed wiring and IC, dry film, image formation such as relief image and image duplication, photocurable ink, paint, adhesive, etc. Extremely useful.

[Brief description of drawings]

FIG. 1 shows an infrared absorption spectrum of I-3 by a KBr method.

FIG. 2 shows an absorption spectrum of I-3 in tetrahydrofuran.

Claims (1)

[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 comprises (a) the following general formula: A sensitizer represented by [I] and (In the formula, R ^{1 to} R ³ are each a hydrogen atom, a halogen atom, an alkyl group, an aryl group, an aralkyl group, an acyl group, an alkoxycarbonyl group, a substituted or unsubstituted hydrocarbon ring residue, a substituted or unsubstituted hydrocarbon ring residue, Heterocyclic residue or -SO
₃ represents a -R ^5, R ⁴ represents a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, a cyano group, a substituted or unsubstituted hydrocarbon ring residue or a substituted or unsubstituted heterocyclic residue, R ⁵ represents a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, an alkali metal atom or a quaternary ammonium group, and ring A is a substituted or unsubstituted 1 to 2 nucleus hydrocarbon ring or a substituted or unsubstituted heterocycle. Represents X ¹
And X ² each represent a halogen atom, an alkyl group, an aryl group, an aralkyl group, a substituted or unsubstituted hydrocarbon ring residue or a substituted or unsubstituted heterocyclic residue. (B) A photopolymerizable composition containing a titanocene compound capable of generating an active radical upon irradiation with light in the presence of the sensitizer.