JPH08100012A - Near-infrared polymerization initiator - Google Patents

Abstract

PURPOSE: To obtain a photopolymerization initiator improved in the rate of polymerization and the ability to polymerize a monomer in the presence of oxygen by using a cationic colorant having an absorption in the region of wavelengths of near-infrared rays and a specified boron-based catalyst as the essential components. CONSTITUTION: This initiator is prepared by mixing a cationic colorant (A) represented by formula I [wherein D<+> is a cation having an absorption in the region of near-infrared rays; and A<-> is a quaternary boron anion represented by formula II (wherein R1 to R4 are each an alkyl, an aryl, a substituted alkyl or the like) or another ion)] with a boron-based catalyst (B) represented by formula III (wherein R5 to R8 are each H, an alkyl, an aryl, a substituted alkyl or the like; and R9 to R12 are each an alkyl, an aryl, a substituted silyl or the like, provided that at least one of them is silyl or substituted silyl). Although the mixing ratio between components A and B may be arbitrary, it is desirably 10:1 to 1:50 (by mole). This initiator is used in such an amount that the amounts of components A and B are each 0.001wt.% or above based on the entire polymerizable composition.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a photopolymerization initiator having an improved polymerization initiation ability. More specifically, it relates to a polymerization initiator using near-infrared light capable of efficiently performing photopolymerization by using a special boron-based catalyst.

[0002]

2. Description of the Related Art Conventionally, photopolymerization is used for curing, drying and printing coatings.
It is used for various applications such as resin convex printing, print substrate making, resist or photomask, black and white or color transfer coloring sheet or making coloring sheet,
In particular, recently, from the viewpoints of global environment problems, energy saving, labor saving in response to rising labor costs, etc., attention has been paid to the features of photopolymerization, such as the fact that polymerization is possible at room temperature, quick drying, and the possibility of solvent-free use. , Is being developed. For example, curing with ultraviolet light is a method in which a polymerizable monomer is rapidly cured by irradiating with ultraviolet light of 200 to 400 nm, and it is put into practical use in various industrial fields. In addition, in recent years, since it is possible to photopolymerize thick film coating that is restricted in use due to its low transmittance of ultraviolet light and a colored coating film containing a pigment with a high hiding ratio, Also, development of a photopolymerization initiator using near infrared light having a long wavelength is underway (for example, JP-A-5-194619).

Among these photopolymerization techniques, a photopolymerization initiator in which a light absorbing dye and a quaternary boron salt substituted with four substituents are combined has attracted attention (for example, Japanese Patent Laid-Open No. 62-62). 143044, JP-A-2-4804). This technology is a system that utilizes radicals generated from a boron compound that is electron-transferred to a dye excited by light to initiate polymerization, and is superior to conventional photopolymerization initiation systems in terms of electron transfer and radical generation efficiency. In addition, there is a feature that any light absorbing compound can be used.
However, there is a drawback that it is not practically sufficient in terms of sensitivity to light, polymerization rate, etc., and as a method for solving these drawbacks, a complex of a near-infrared light absorbing dye and a boron salt having a substituted silyl group is referred to as a complex. A method using a special light-absorbing compound has been proposed (Japanese Patent Laid-Open No. Hei 4 (1999) -264242).
No. 261406), a highly versatile improvement method using a dye that is generally easily available has not been known so far.

[0004]

The present invention provides improved near-infrared photoinitiator systems using commonly available cationic dyes with improved photosensitivity, polymerization rate and in the presence of oxygen. It is an object to provide a polymerization initiator having a polymerization initiation ability.

[0005]

Means for Solving the Problems The inventors of the present invention have repeatedly studied the structure of a boron compound used in combination with a dye that absorbs light energy in order to solve the above problems, and as a result, found that the substituent group bonded to the boron atom When at least one of them is a silyl group or a substituted silyl group, it was found that, when combined with a general cationic dye, a polymerization initiation ability far superior to that of a conventional initiator system is exhibited, and the present invention was completed. It was That is, according to the present invention, a cationic dye having absorption in the near-infrared wavelength region and a boron-based catalyst represented by the general formula (3) are represented by the general formula (3);

[0006]

Embedded image

(In the formula, R ₅ , R ₆ , R ₇ and R ₈ are each independently a hydrogen atom, an alkyl group, an aryl group, an allyl group, an aralkyl group, an alkenyl group, an alkynyl group, a heterocyclic group or a substituted alkyl group. Group, a substituted aryl group, a substituted allyl group, a substituted aralkyl group, a substituted alkenyl group, or a substituted alkynyl group, wherein R ₉ , R ₁₀ , R ₁₁ and R ₁₂ are each independently an alkyl group, an aryl group, an allyl group, An aralkyl group, an alkenyl group, an alkynyl group, a silyl group, a heterocyclic group, a halogen atom, a substituted alkyl group, a substituted aryl group, a substituted allyl group, a substituted aralkyl group, a substituted alkenyl group, a substituted alkynyl group or a substituted silyl group, R
_At least one of ₉ , R ₁₀ , R ₁₁ and R ₁₂ is a silyl group or a substituted silyl group. To form a photopolymerization initiator, and a photopolymerization initiator capable of polymerizing a polymerizable unsaturated compound at a practical rate by irradiation with near infrared light is obtained.

The polymerization initiator in the present invention is a photopolymerizable material such as printing ink, resist, adhesive, furniture, electronic material, painting of construction material, carpentry, metal, plastics painting, car body, interior, It can be used for painting bumpers, coating inorganic materials, and the like. When the cationic dye of the general formula (1) and the boron-based catalyst of the general formula (3), which constitute the present invention, are used together, the cationic dye is decomposed by light, and the color of the cationic dye is decolored and radicals are generated. Occurs, and when a polymerizable unsaturated compound coexists, polymerization is initiated. The decoloring reaction of the cationic dye is an irreversible reaction, and the great feature of the present invention is that the color of the cationic dye does not impair the hue of the polymer. When the boron-based compound having a silyl substituent of the present invention is used in place of the conventionally used boron-based catalyst as a measure for improving the polymerization rate while taking advantage of the characteristics of this photopolymerization initiator system, the polymerization rate is significantly improved. The photopolymerization reaction is completed within a practical polymerization time.

In the case of conventionally used boron-based compounds, all the substituents are carbon-based substituents such as alkyl groups and aryl groups, and therefore the radicals generated by photoreaction are alkyl radicals (eg butyl radicals). However, there is a problem in obtaining a practical polymerization initiation rate in terms of stability, polymerization initiation ability, and the like. However, when the silicon-based catalyst having a silyl substituent of the present invention is used, a silyl radical having a free radical on a silicon atom can be generated by a photoreaction, which is superior in stability and the like to conventional alkyl radicals. It is estimated that the polymerization initiation efficiency is improved.

The boron compound having a silyl substituent of the present invention is said to be first synthesized by D. Seyfert et al. (Journal of Organic Chemistry 1961 303.
As an example of application to near-infrared photopolymerization, a combination of a special near-infrared light absorbing dye whose counter anion is a silylboron compound and a silylboron / ammonium complex is disclosed in the above-mentioned JP-A-4-261406. Is described only in the text, and there is no detailed description about the improvement of the polymerizability or the polymerization reaction in the presence of oxygen in the above-mentioned published patent specifications. No example was known that was used for near-infrared photopolymerization in combination with. The boron-based catalyst according to the present invention is represented by the general formula (3), and at least one of the substituents R _{5 to} R ₈ bonded to the boron atom has the general formula (6).
Is a silyl group or a substituted silyl group. Formula _{(6); - SiR 13 R} 14 R 15 ( wherein, R _13, R ₁₄ and R ₁₅ each independently represent a hydrogen atom, an alkyl group, an aryl group, an allyl group, an aralkyl group, an alkenyl group, an alkynyl group, Heterocyclic group, silyl group, substituted alkyl group, substituted aryl group, substituted allyl group,
A substituted aralkyl group, a substituted alkenyl group, a substituted alkynyl group, a substituted heterocyclic group, and a substituted silyl group. )

Specific examples of the boron anion in the boron-based catalyst of the present invention include triphenylsilyltriphenylboron ion, diphenylmethylsilyltriphenylboron ion, dimethylphenylsilyltriphenylboron ion, tritoluylsilyltriphenylboron. Ion, triphenylsilyltrianisylboron ion, di (triphenylsilyl) diphenylboron ion, triphenylsilyltributylboron ion, triphenylsilyltrimethylboron ion, tri-n-butyl (dimethylphenylsilyl) boron ion and the like.

In particular, the stability of the generated silyl radical,
Considering the polymerization initiation ability and the like, at least one of the substituents of the silyl group is preferably an aryl group such as a phenyl group, a toluyl group, a naphthyl group or a substituted aryl group. Further, considering the ease of production and the like, triphenylsilyl group, tritoluylsilyl group, diphenylmethylsilyl group and the like are particularly preferable as the substituted silyl group. Further, in consideration of the stability of the compound, the ease of production, etc., the substituent of the boron atom is preferably a compound in which one of the substituents is substituted with a silyl group, and more preferably three (substituted) aryl groups and one Is a triarylsilylboron compound substituted with the silyl group of. The counter ion has the general formula (7);

[0013]

[Chemical 6]

(Wherein R ₅ , R ₆ , R ₇ and R ₈ are each independently a hydrogen atom, an alkyl group, an aryl group, an allyl group, an aralkyl group, an alkenyl group, an alkynyl group, a heterocyclic group or a substituted alkyl group. Group, a substituted aryl group, a substituted allyl group, a substituted aralkyl group, a substituted alkenyl group, or a substituted alkynyl group.).

The cation dye represented by the general formula (1) of the present invention may be any dye having an absorption in the near infrared wavelength region, and specifically, a cation having an absorption in the wavelength region of 700 nm or more. It is a compound having absorption in a wavelength region of 780 nm or more. Since near-infrared light has a longer wavelength and is superior in light transmittance to ultraviolet light or visible light that is generally used in the past, it is difficult to use conventional ultraviolet light to add various pigments with high light hiding property. Good photopolymerization can be carried out even for the composition, the thick composition and the like.

The cation (D ⁺ ) of the present invention is not particularly limited as long as it has absorption in a wavelength region of 700 nm or more, but preferable examples include cyanine, xanthene, oxazine, thiazine, diarylmethane and triaryl. Examples include methane and cations of pyrylium cation dyes. Typical examples of such cation dyes include cations as shown in Table 1.

[0017]

[Table 1]

[0018]

[Table 1]

The counter anion A ^- is a quaternary boron anion represented by the general formula (2) or any anion other than the boron anion, for example, a sulfonate anion such as p-toluenesulfonate. ClO ₄ anion, SbF ₆ anion, PF ₆ anion, halogen anions such as chlorine and bromine, various carboxylate anions such as acetic acid and benzoic acid, nitrate ions, various sulfate anions,
Examples thereof include phosphate anions, and metal anions such as tungstic acid, titanic acid, and zirconic acid. Among them, the quaternary boron anion of the general formula (2), p-toluenesulfonate anion, ClO ₄ , and halogen anion are particularly preferable. General formula (2);

[0020]

[Chemical 7]

(Wherein R ₁ , R ₂ , R ₃ and R ₄ are each independently an alkyl group, an aryl group, an allyl group, an aralkyl group, an alkenyl group, an alkynyl group, a heterocyclic group, a halogen atom or a substituted alkyl group. Group, substituted aryl group, substituted allyl group, substituted aralkyl group, substituted alkenyl group, and substituted alkynyl group.)

Specific examples of the quaternary boron anion include n-
Butyltriphenylboron ion, n-octyltriphenylboron ion, n-butyltrianisylboron ion, di-n-dodecyldiphenylboron ion, tetraphenylboron ion, triphenylnaphthylboron ion, tetrabutylboron ion, BF ₄ anion And the like. More specifically, the anions and the like described in the patent specification filed by the present inventors earlier (JP-A-6-75374) can be mentioned.

The photopolymerization initiator of the present invention is generally used as a photopolymerizable composition in combination with a polymerizable unsaturated compound. The polymerizable unsaturated compound used at that time includes a polymerizable oligomer and a polymerizable monomer, and as the polymerizable oligomer, a urethane acrylate resin, a polyester acrylate resin, an unsaturated polyester resin, an epoxy acrylate resin, a silicone acrylate resin, a melamine acrylate resin. And (meth) acrylic functional polyorganosilsesquioxane disclosed in JP-A-4-28722. These oligomers have various compounds produced by various manufacturers and are easily available. The above-mentioned polymerizable oligomer is the main component that determines the physical properties of the polymerization product, and is selected according to the physical properties required for various applications such as hardness, strength, durability, adhesion, etc., and is mixed in an arbitrary amount.

As the polymerizable monomers, esterified products of (meth) acrylic acid and monohydric alcohol, vinylbenzenes such as styrene, vinyltoluene and chlorostyrene, vinyl ethers such as vinyl isobutyl ether and 2-ethylhexyl vinyl ether, (Meth) acrylonitrile, (meth) acrylamide, (meth) acrylic compounds such as methylenebisacrylamide, vinyl acetates such as vinyl acetate, vinyl propionate, vinyl benzoate, allyl alcohol, allyl acetate, diallyl phthalate, etc. Examples thereof include monomers containing an allyl group.

Further, as the monomer, a hydroxyl group-containing monomer such as 2-hydroxyethyl (meth) acrylate or 2-hydroxypropyl (meth) acrylate; an adduct of polyisocyanate such as butyl isocyanate or phenyl isocyanate with the above hydroxyl group-containing monomer;
An addition product of phosphoric acid and the above-mentioned hydroxyl group-containing monomer; nitrogen-containing unsaturated monomers such as N-vinylpyrrolidone, N-vinylcarbazole, N-vinylacetamide and vinylpyridines can also be used. Further, as the monomer, di-, tri- or tetravinyl compounds such as diethylene glycol diacrylate, 1,6-hexanediol dimethacrylate, trimethylolpropane triacrylate, pentaerythritol trimethacrylate and pentaerythritol tetraacrylate; A product obtained by reacting (meth) acrylic acid with an adduct of ethylene oxide and ethylene oxide; A product obtained by reacting (meth) acrylic acid with an adduct of polyhydric alcohol and propylene oxide; A product obtained by reacting (meth) acrylic acid with an adduct with ε-caprolactone; a phosphorus-containing polymerizable unsaturated monomer and the like are included. A more detailed specific example was filed earlier (Japanese Patent Laid-Open No. 6-75).
No. 374).

The polymerization reaction of the composition containing the polymerization initiator, the polymerizable unsaturated compound and the like of the present invention is achieved by light irradiation with a light generating device having a spectral distribution in the near infrared region.
For example, a halogen lamp, a xenon lamp, sunlight, etc. In the case of ultraviolet light that has been used in the past, relatively expensive irradiation devices such as high-pressure mercury lamps and metal halide lamps are required, and there are practical problems in terms of safety such as ozone generation and the possibility of skin cancer. However, in the case of near infrared light, a relatively inexpensive irradiation device can be used, and it is also characterized by high safety.

In the photopolymerization reaction, it is preferable to irradiate with light under a low oxygen concentration in order to reduce polymerization inhibition by oxygen. For example, it is desirable to blow the above-mentioned inert gas onto the surface of the cured product in an atmosphere of an inert gas such as nitrogen, argon, carbon dioxide or the like to reduce the oxygen concentration and accelerate the polymerization. As described above, the polymerization initiator containing the boron-based catalyst of the present invention is superior in the polymerization initiation ability in the presence of oxygen as compared with the case of using the conventional boron-based catalyst,
The polymerization reaction can be performed even in the presence of a high concentration of oxygen.

When the near infrared photopolymerization initiator of the present invention is used, conventionally known oxygen scavengers, various polymerization accelerators and the like can be used in combination. As an oxygen scavenger, phosphine, phosphite, phosphonate, various reducing agents, singlet oxygen quencher, etc.
-A variety of compounds known as chain transfer agents such as phenylglycine, pentamethylaniline, 2-mercaptobenzothiazole, photoacid generators such as naphthoquinonediazide compounds, triazine compounds, aromatic onium compounds, and bisimidazole compounds Examples thereof include electron-accepting substances.

The cationic dye represented by the general formula (1) and the boron-based catalyst represented by the general formula (2) in the present invention can be used in an arbitrary ratio, and generally 10: 1 to 1:50.
Although it is used in a (molar ratio) ratio, it is preferable to use the boron-based catalyst in a larger amount than the cationic dye. That is,
The range of 1: 1 to 1:10 (molar ratio) is particularly preferable. The cationic dye and the boron-based catalyst of the present invention may be used in an amount of 1
It is also possible to use one kind or a mixture of two or more kinds. That is, two or more kinds of cation dyes having different absorption wavelengths can be used together to utilize irradiation light over a wide range, and the boron-based catalyst is not limited to being used alone. It may be used in combination with a conventionally used boron-based catalyst that does not contain a conventional silyl group in consideration of cost, solubility, polymerization activity and the like.

The polymerization initiator of the present invention can achieve the object of the present invention by using a cationic dye and a boron catalyst in an amount of 0.001% by weight or more based on the whole polymerizable composition. If it is less than that, the polymerization may not be performed sufficiently. It is preferably in the range of 0.01 to 10% by weight.
It is not preferable from the economical point of view to use too much.
Further, optional additives and fillers can be added to the polymerizable composition containing the initiator of the present invention. Examples of the additive here include a thickener, a leveling agent, a thixotropic agent, a dispersant and the like which are generally used as an additive for paints, and the filler includes an organic substance, an inorganic substance, or a mixture thereof. Examples include composites and mixtures. Further, as described above, since the polymerization initiator of the present invention uses a cationic dye having absorption in a long wavelength region as compared with ultraviolet light which has been conventionally used, carbon black or the like having low light transmittance is used. Even if it contains a black pigment, a metallic pigment such as aluminum or titanium, photopolymerization can be caused, and various pigments thereof can be added.

As described above, the photopolymerization initiator of the present invention is suitable as a polymerization initiator for photocurable materials such as paints, inks and adhesives. These photo-curable materials can be used as solvent-free materials and are expected to contribute to the improvement of the global environment. Conventional reaction curable compositions required a large amount of solvent to dissolve the polymer component before curing, but photo-curable materials can use a reactive compound as a diluent, so essentially solvent-free is possible. Therefore, it becomes possible to eliminate the solvent or to drastically reduce the amount of the solvent.

Of course, there is no problem even if it is used in a form diluted with a conventional solvent, but the amount of solvent used is as small as possible from the viewpoints of resource saving from the viewpoint of global environment, prevention of environmental damage and cost. Is desirable. As the solvent that can be used at that time, as long as it is a compound that does not impair the chemical stability of the cationic dye and the boron-based catalyst, a general solvent that has been conventionally used for paints, for example, an aromatic solvent such as toluene or xylene. Hydrocarbons, aliphatic hydrocarbons such as heptane, hexane and pentane, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, ethers such as diethylene glycol dimethyl ether and triethylene glycol dimethyl ether, esters such as ethyl acetate, butyl acetate and amyl acetate. And monoethers of ethylene glycol such as methyl cellosolve and ethyl cellosolve can be used. These solvents can be used alone or in combination of two or more. Further, it is also possible to use water as a solvent or a dispersion medium.

[0033]

EXAMPLES The present invention will be described below with reference to examples. (Example 1) Pentaerythritol triacrylate-
Hexamethylene diisocyanate-urethane prepolymer 70 g, nonaethylene glycol diacrylate 30
g, and 30 g of acetone were thoroughly mixed, and then 0.1 g of a near-infrared light absorbing cation dye (complex No. 3 in Table 1, anion is n-butyltriphenylboron anion) and a silylboron catalyst (tetrabutylammonium). Triphenylsilyltriphenylboron) 0.3 g was dissolved and sample 1
And

(Example 2) Sample 2 was prepared in the same manner as in Example 1 except that the boron-based catalyst was changed to tetramethylammoniumtriphenylsilyltriphenylboron.

Example 3 Sample 3 was prepared in the same manner as in Example 1 except that the boron-based catalyst was changed to tetrabutylammonium (phenyldimethylsilyl) triphenylboron.

Example 4 Sample 4 was prepared in the same manner as in Example 1 except that the boron-based catalyst was changed to tetrabutylammonium (diphenylmethylsilyl) triphenylboron.

Example 5 Sample 5 was prepared in the same manner as in Example 1 except that the counter anion of the near infrared absorbing dye was changed to the paratoluene sulfonate anion.

Comparative Example 1 Comparative sample 1 was prepared in exactly the same manner as in Example 1 except that the boron-based catalyst was changed to tetrabutylammonium n-butyltriphenylboron.

Example 6 Sample 6 was prepared in exactly the same manner as in Example 1 except that the cation dye was changed from No. 3 in Table 1 to the dye of No. 1 (anion is n-butyltriphenylboron anion).

Comparative Example 2 Comparative sample 2 was prepared in exactly the same manner as in Example 6 except that the boron-based catalyst was changed to tetrabutylammonium n-butyltriphenylboron.

Example 7 Sample 7 was prepared in exactly the same manner as in Example 1 except that the cation dye was changed to the dye of Table 1 No. 2 (the anion is n-butyltriphenylboron anion). (Comparative Example 3) Comparative Sample 3 was prepared in exactly the same manner as in Example 7 except that the boron-based catalyst was changed to tetrabutylammonium n-octyltriphenylboron. (Example 8) Sample 8 was prepared in exactly the same manner as in Example 1 except that the cation dye was changed to the dye of Table 1 No. 5 (the anion was n-butyltriphenylboron anion). (Comparative Example 4) Example 8 except that the boron-based catalyst was changed to tetrabutylammonium n-butyltriphenylboron.
Comparative sample 4 was prepared in exactly the same manner as.

[Polymerization test and evaluation of polymerizability of sample] The prepared sample was placed on an aluminum substrate by an applicator to 1
It is applied to a thickness of 00 μm, and the wavelength is 800-
A halogen lamp with an output of 1500 W having a spectral distribution in the range of 950 nm was irradiated for 3 minutes. The obtained coating film was peeled off and the residual double bond was quantified by FT-IR. Table 2 shows the results. The less residual double bonds, the more the polymerization is progressing. In the photo-curing reaction, it is generally said that 20-40% of double bonds remain even after the reaction is completed, and when the photopolymerization initiator of the present invention is used, the photo-reaction is almost completed by irradiation with light for 3 minutes. I understand. On the other hand, when a conventional boron-based catalyst is used, 50% or more of the residual double bonds remain in the simultaneous light irradiation, and the photoreaction is not completed.

[0043]

[Table 2]

(Example 9) Polymerization reaction in the presence of oxygen As in the above polymerization test, the substrate coated with the composition of Example 1 was irradiated with the halogen lamp for 10 minutes in an atmosphere having an oxygen concentration of 0.5%. . The surface of the coating film was sufficiently cured and no surface tack was observed.

(Comparative Example 5) Similar to Example 9, Comparative Example 1
The substrate coated with the above composition was irradiated with the halogen lamp for 10 minutes in an atmosphere with an oxygen concentration of 0.5%. The surface of the coating film did not seem to be cured at all, and the composition adhered to the finger when touched with the finger.

[0046]

INDUSTRIAL APPLICABILITY The present invention provides a photopolymerization initiator having improved polymerization rate and polymerizability in the presence of oxygen.

Claims (3)

[Claims] 1. A near-infrared photopolymerization initiator comprising a cationic dye represented by the general formula (1) and a boron-based catalyst represented by the general formula (3) as essential components. General formula (1); D ⁺ · A ⁻ (In the formula, D ⁺ is a cation having an absorption in the near infrared light region, and A ⁻ is a quaternary boron anion represented by the general formula (2). Or various anions other than boron anion) General formula (2); (In the formula, R ₁ , R ₂ , R ₃ and R ₄ are each independently an alkyl group, an aryl group, an allyl group, an aralkyl group, an alkenyl group, an alkynyl group, a heterocyclic group, a halogen atom,
A substituted alkyl group, a substituted aryl group, a substituted allyl group, a substituted aralkyl group, a substituted alkenyl group or a substituted alkynyl group is shown. ) General formula (3); (In the formula, R ₅ , R ₆ , R ₇ and R ₈ are each independently a hydrogen atom, an alkyl group, an aryl group, an allyl group, an aralkyl group, an alkenyl group, an alkynyl group, a heterocyclic group, a substituted alkyl group, a substituted alkyl group, An aryl group, a substituted allyl group, a substituted aralkyl group, a substituted alkenyl group, or a substituted alkynyl group, wherein R ₉ , R ₁₀ , R ₁₁ and R ₁₂ are each independently an alkyl group, an aryl group, an allyl group, an aralkyl group, An alkenyl group, an alkynyl group, a silyl group, a heterocyclic group, a halogen atom, a substituted alkyl group, a substituted aryl group, a substituted allyl group, a substituted aralkyl group, a substituted alkenyl group, a substituted alkynyl group or a substituted silyl group, R ₉ , R ₁₀ , R
_At least one substituent of ₁₁ and R ₁₂ is a silyl group or a substituted silyl group. ) 2. The photopolymerization initiator according to claim 1, wherein the boron-based catalyst is represented by the following general formula (4). General formula (4); (In the formula, R _{5 to} R ₁₁ are the same as in the general formula (3), R ₁₃ and R ₁₄
And R ₁₅ are each independently a hydrogen atom, an alkyl group, an aryl group, an allyl group, an aralkyl group, an alkenyl group, an alkynyl group, a heterocyclic group, a silyl group, a substituted alkyl group, a substituted aryl group, a substituted allyl group, a substituted aralkyl group. , A substituted alkenyl group, a substituted alkynyl group, a substituted heterocyclic group or a substituted silyl group. ) 3. The photopolymerization initiator according to claim 1, wherein the boron-based catalyst is represented by the following general formula (5). General formula (5); (In the formula, R _{5 to} R ₈ and R _{13 to} R ₁₅ are the same as in the general formula (4), and Ar is an allyl group or a substituted aryl group.)