JP2751453B2 - Photopolymerization initiator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a photopolymerization initiator used for polymerizing an ethylenically unsaturated compound or the like, and more particularly, to a photopolymerization initiator having a wavelength of 350
It relates to a photopolymerization initiator sensitive to light in the range of ~ 700 nm.

<Prior Art> It is known that monomers, dimers, trimers, oligomers and polymers containing an ethylenically unsaturated bond in a molecule undergo photopolymerization in the presence of a photopolymerization initiator. This phenomenon is used in paints, adhesives, printing inks, printing plates, printed wiring plates, and the like, and has recently been applied to medical fields such as dental resin agents.

As the photopolymerization initiator used in the polymerization, various substances have been conventionally known. Actually, for example, benzoin compounds such as benzoin, benzoin methyl ether and benzoin ethyl ether; benzyl, benzophenone, acetophenone, Michler's ketone Azo compounds such as azobisisobutyronitrile and azodibenzoyl; sulfur compounds such as dibenzothiazolyl sulfide and tetrathiuram disulfide; halogen compounds such as carbon tetrachloride and tribromophenyl sulfone; -Benzanthraquinone or the like is used.

<Problems to be Solved by the Invention> However, when the ethylenically unsaturated compound is polymerized by using the photopolymerization initiator, the polymerization is performed by radical polymerization, so that the polymerization is susceptible to polymerization inhibition by oxygen in the air. In order to improve the surface curability, there arise problems such as a need to increase the light irradiation intensity, increase the concentration of the initiator, or increase the irradiation time.

Therefore, an object of the present invention is to initiate photopolymerization upon exposure to a wide range of wavelengths of light, excellent surface curability, deep curing depth,
Another object of the present invention is to provide a photopolymerization initiator having good sensitivity.

<Means for Solving the Problems> According to the present invention, the following general formula (I) (Wherein, R ₁ and R ₂ each represent a hydrogen atom or a lower alkyl group, and R ₃ represents an alkyl group, an ester residue, or an acyl group excluding a benzoyl group). , The following general formula (II) (Wherein R ₄ and R ₆ each represent a tertiary alkyl group having 4 to 8 carbon atoms or a tertiary aralkyl group having 9 to 12 carbon atoms, and R ₅ and R ₇ represent a hydrogen atom and A tertiary alkoxy group of 8 or a tertiary aralkyloxy group of 9 to 12 carbon atoms).

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

The photopolymerization initiator of the present invention contains a specific substituted aromatic amine and a specific benzophenone group-containing polyvalent peroxyester.

The substituted aromatic amines used in the present invention can be represented by the following general formula (I): In the formula, R ₁ and R ₂ each represent a hydrogen atom or a lower alkyl group, and R ₃ represents an alkyl group, an ester residue, or an acyl group excluding a benzoyl group. Examples of the substituted aromatic amine represented by the general formula (I) include N, N-diethylaminobenzoic acid, N, N-dimethylaminobenzoic acid,
Ethyl N, N-dimethylaminobenzoate, ethyl N, N-diethylaminobenzoate, isoamyl N, N-dimethylaminobenzoate, 2-ethylhexyl N, N-dimethylaminobenzoate, N, N-dimethylaminoacetophenone, N, N-
Examples thereof include diethylaminoacetophenone, N, N-dimethylparatoluidine, N, N-diethylparatoluidine, N, N-dimethylaminobenzaldehyde and the like. When used, they can be used alone or as a mixture. More preferably, it is desirable to use a substituted aromatic amine represented by the general formula (I) having an absorption at a wavelength of 300 to 700 nm. To prepare the substituted aromatic amines, for example, when preparing ethyl N, N-dimethylamine benzoate, it can be obtained by a method of reacting N, N-dimethylaminobenzoic acid chloride with ethyl alcohol. it can.

The benzophenone group-containing polyvalent peroxyester used in the present invention can be represented by the following general formula (II): In the formula, R ₄ and R ₆ each represent a tertiary alkyl group having 4 to 8 carbon atoms or a tertiary aralkyl group having 9 to 12 carbon atoms, and R ₅ and R ₇ represent a hydrogen atom and 4 to 8 carbon atoms, respectively. A tertiary alkoxy group or a tertiary aralkyloxy group having 9 to 12 carbon atoms.
When R _{4 to} R ₇ are a tertiary alkyl group or tertiary alkoxy group having 9 or more carbon atoms, a tertiary aralkyl group or tertiary aralkyloxy group having 13 or more carbon atoms, production is difficult. Examples of the benzophenone-containing polyvalent peroxyester represented by the general formula (II) include, for example, 3,3 ′, 4,
4'-tetra (t-butylperoxycarbonyl) benzophenone, 3,3 ', 4,4'-tetra (t-amylperoxycarbonyl) benzophenone, 3,3', 4,4'-tetra (t-hexylperoxycarbonyl ) Benzophenone, 3,3 ', 4,4'-tetra (t-octylperoxycarbonyl) benzophenone, 3,3', 4,4'-tetra (cumylperoisylcarbonyl) benzophenone, 3,3 ', 4,
4'-tetra (p-isopropylcumylperoxycarbonyl) benzophenone, 3,3 '-(di-tert-butylperoxycarbonyl) -4,4'-(dicarboxy) benzophenone or 3,3 '-(di-t -Hexylperoxycarbonyl) -4,4'-dicarboxy) benzophenone and the like, and when used, they can be used alone or as a mixture. To prepare the benzophenone-containing polyvalent peroxyesters, for example, 3,
When preparing 3 ', 4,4'-tetra (t-butyloxycarbonyl) benzophenone, 3,3', 4,4'-tetra (chloroformyl) benzophenone and t-butyl hydroperoxide are dissolved in an aqueous alkaline solution. And the like.

In the present invention, the blending ratio of the substituted aromatic amines and the benzophenone-containing polyvalent peroxyester is, by weight ratio, substituted aromatic amines: benzophenone-containing polyvalent peroxyester, preferably 0.1 to 99. .
The range is from 9: 99.9 to 0.1, particularly preferably from 1 to 90:99:10. If the compounding ratio is out of the above range, excellent effects cannot be obtained, which is not preferable.

In order to prepare the photopolymerization initiator of the present invention, the photopolymerization initiator can be obtained by mixing the substituted aromatic amine with a benzophenone group-containing polyvalent peroxyester. At this time, in addition to the essential components, for example, additives such as a pigment, a filler, a dye, a sensitizer, a thermal polymerization inhibitor, a plasticizer, a solvent, and a binder may be appropriately compounded.

The photopolymerization initiator of the present invention can be preferably used when polymerizing an ethylenically unsaturated compound or the like. Examples of the ethylenically unsaturated compound include all monomers, dimers, trimers, oligomers or polymers containing an ethylenically unsaturated bond in the molecule, such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid. Examples include unsaturated carboxylic acids such as acids and itaconic acids, and unsaturated carboxylic acid derivatives thereof. Specifically, for example, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate,
Monoesters such as 2-ethylhexyl (meth) acrylate, phenyl (meth) acrylate and benzyl (meth) acrylate; hydroxyalkyl esters such as 2-hydroxyethyl (meth) acrylate; ethylene glycol (meth) acrylate and polyethylene glycol diester Polyhydric esters such as (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate; (meth) acrylonitrile; (meth) acrylamide; N-substituted (Meth) acrylamide; vinyl esters such as vinyl acetate, vinyl propionate, vinyl acrylate, and vinyl succinate; vinyl ethers, styrene, alkylstyrene, and halogenated Compounds such as butylated styrene, N-vinylpyrrolidone, diallyl phthalate diallyl maleate, triallyl isocyanate, triallyl phosphate; curable resins having a fumarate group, a maleate group, an allyl group, and a (meth) acrylate group And unsaturated polyesters, unsaturated acrylic resins, isocyanate-modified acrylate oligomers, polyester acryl oligomers, polyether acryl oligomers, and the like. When used, they can be used alone or as a mixture.

In order to use the photopolymerization initiator of the present invention, for example, the photopolymerization initiator of the present invention is mixed with the above-mentioned ethylenically unsaturated compound or the like, and photopolymerization or photocuring can be performed by irradiating light.

The amount of the photopolymerization initiator of the present invention used in the photopolymerization or photocuring, based on 100 parts by weight of the ethylenically unsaturated compound, is preferably 0.01 to 40 parts by weight, particularly preferably 0.1 to 20 parts by weight. Range of parts. If the amount is more than 40 parts by weight, the light transmittance is decreased, unreacted photopolymerization initiator remains, and the physical properties of the obtained polymer may be deteriorated. If the amount is less than 0.01 part by weight, the polymerization reaction is not completely performed, and unreacted ethylenically unsaturated compounds remain, which is not preferable. The light irradiated for performing the photopolymerization or photocuring has a wavelength of 35.
Light from 0 to 700 is preferred. As a usable light source, any light source that emits light having a wavelength within the above range can be used.Specifically, for example, sunlight, a mercury lamp, a hydrogen discharge tube, a quinocene lamp, a flash discharge tube, a tungsten lamp, Examples include a halogen lamp, a metal halide lamp, and a laser.

<Effect of the Invention> The photopolymerization initiator of the present invention is sensitive to light having a wavelength in the range of 350 to 700 nm, and has excellent surface curability and light transmittance, etc., and a deep curing depth can be obtained. By combining with a compound, it can be used to cure paints, adhesives, printing inks, printing boards, printed wiring boards, dental resin materials, etc., and it is also possible to polymerize and cure thick films and molded products. . In addition, the photopolymerization initiator of the present invention has higher sensitivity than conventional ultraviolet initiators, and thus is excellent in workability and economic efficiency, and furthermore, visible light that is harmless to the human body can be used. It is also excellent in safety.

<Examples> Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

Examples 1 to 5 Substituted aromatic amines and peroxyesters were mixed at the mixing ratios shown in Table 1 to prepare photopolymerization initiators. Next, the obtained photopolymerization initiator was added and dissolved in a mixture of 100 parts of dipentaerythritol hexaacrylate and 100 parts of methyl methacrylate to obtain a photopolymerization composition. The obtained photopolymerizable composition was applied to a commercially available acrylic plate using a bar coater so that the cured film became about 20 μm, and then irradiated with a halogen lamp so that the average illuminance was about 20 mw / cm ² . After the light irradiation for 10 minutes, the pencil height of the coating film surface was measured by JIS K5400, and the surface curability was evaluated. Table 1 shows the results.

Comparative Examples 1 to 5 Table 1 shows substituted aromatic amines or peroxyesters.
The procedure was performed in the same manner as in Example 1 except for using as shown in Table 1. Table 1 shows the results.

From the results in Table 1, it can be seen that the photopolymerization initiator of the present invention improves the surface curability of the obtained cured product.

Examples 6 to 11 and Comparative Example 6 Substituted aromatic amines and peroxyesters were mixed at the mixing ratios shown in Table 2 to prepare photopolymerization initiators. Next, the obtained photopolymerization initiator was dissolved in an ethylenically unsaturated compound shown in Table 2 to obtain a photosensitive solution. The obtained photosensitive solution was filled in a polyethylene cylinder having an inner diameter of 10 mm and a depth of 10 mm, and irradiated with light from above the cylinder with a halogen lamp (15 V-150 w) to be polymerized and cured. In Examples 7 to 11 and Comparative Example 6, in order to clarify the effect of the emission wavelength, a colored glass filter manufactured by Toshiba Corp.
9 "or" Y-45 "was set, and light was irradiated from the halogen lamp to perform polymerization and curing.

Incidentally, the radiation intensity in the cylindrical upper part of the case not including the color glass filter was measured by d shake Sir mobile, but was 50 mW / cm ^2, in case of installing the color glass filter, the radiation intensity 1 / It decreased to 2/3 or less.
The initiation efficiency of the photopolymerization initiator was determined by taking out the cured polymer from the cylinder, removing the unreacted material, and measuring the curing depth of the photosensitive solution using a micrometer. Table 2 shows the results.

As is clear from the results in Table 2, the photopolymerization initiator of the present invention can efficiently polymerize and cure the ethylenically unsaturated compound by irradiating visible light with a halogen lamp for a short time of about 30 to 60 seconds. It has been found that a cured product having a high curing depth can be obtained because of its excellent light transmittance. In addition, from the results when the glass filters of the respective colors were installed, it was found that polymerization curing was effectively performed even with long-wavelength light, although the radiation intensity was reduced to 1/2 to 1/3 or less.

Comparative Examples 7 to 10 Photosensitive liquids were prepared and tested in the same manner as in Examples 6 to 11 and Comparative Example 6, except that the photopolymerization initiator and the ethylenically unsaturated compound shown in Table 3 were used. Table 3 shows the results.

From the results in Table 3, it can be seen that the substituted aromatic amines or the benzophenone group-containing polyhydric peroxyesters alone did not cure sufficiently, and that even when a general tertiary amine and a benzophenone group-containing peroxyester were used in combination, they cured sufficiently. Turned out not to.

Claims (1)

(57) [Claims] 1. A compound represented by the following general formula (I) (Wherein, R ₁ and R ₂ each represent a hydrogen atom or a lower alkyl group, and R ₃ represents an alkyl group, an ester residue, or an acyl group excluding a benzoyl group). , The following general formula (II) (Wherein R ₄ and R ₆ each represent a tertiary alkyl group having 4 to 8 carbon atoms or a tertiary aralkyl group having 9 to 12 carbon atoms, and R ₅ and R ₇ represent a hydrogen atom and A tertiary alkoxy group of 8 or a tertiary aralkyloxy group having 9 to 12 carbon atoms).