JPH06329711A - Photopolymerization initiator and photopolymerizable composition - Google Patents

Abstract

PURPOSE:To obtain a photopolymn. initiator which can easily photopolymerize a pigment-contg. compsn. formerly difficult to photopolymerize by compounding a specific boron compd. with a light-absorbing pigment. CONSTITUTION:A photopolymn. initiator is prepd. by compounding a boron compd. of the formula wherein R1, R2, R3, and R4 are each alkyl, aryl, allyl, aralkyl, alkenyl, alkynyl, silyl, heterocyclic, etc.; and Z<+> is a quaternary ammonium cation, a quaternary pyridinium cation, a quaternary quinolinium cation, a phosphonium cation, or a metal cation (e.g. tetrabutylammonium n- butyltriphenylborate) with a light-absorbing pigment (e.g. an anthraquinone pigment). A photopolymerizable compsn. is prepd. by compounding a polymerizable unsatd. compd. (e.g. styrene), the boron compd., and the light- absorbing pigment.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a photopolymerization initiator and a photopolymerizable composition which can be used in a novel polymerization initiation system.
More specifically, it relates to a photopolymerization initiator in which a specific boron compound and a light absorbing pigment are combined, and a photopolymerizable composition obtained by adding a polymerizable unsaturated compound to the above polymerization initiator.

[0002]

2. Description of the Related Art Conventionally, photopolymerization has been applied to various fields such as curing and printing of coating film, resin convex printing, print substrate preparation, resist or photomask, black and white or color transfer coloring sheet or coloring sheet preparation. It is used, especially from the viewpoint of global environmental problems, energy saving, labor saving in response to rising labor costs, etc., which is a feature of photopolymerization, that it can be polymerized at room temperature, quick-drying, solvent-free, etc. Has been noticed and is being developed.

In the development of printing inks, ultraviolet curable inks have been studied for the purpose of solventlessness, improvement of productivity by rapid curing, or improvement of physical properties of cured films (for example, Japanese Patent Laid-Open No. 1-229084). Kaihei 1-271
469 and JP-A-2-22370). As for the development of paints, rapid drying and curing of colored coating films have been studied (for example, JP-A-52-135341 and JP-A-5-135341).
No. 2-152436, JP-A-2-296875 and JP-A-3-6265), and JP-A-52-152436 disclose pigments or pigments in a system containing a polymerizable unsaturated resin and a photopolymerization initiator. A method for forming a colored cured coating film containing a dye having a high hiding rate is disclosed.

However, curing by ultraviolet light is 200
The polymerizable monomer is rapidly cured by cation polymerization or radical polymerization by irradiating with ultraviolet light of ~ 400 nm, and the thickness of the composition increases even with a colored coating film containing a pigment with a high hiding rate or a transparent material. In addition, there is a problem in that the transmittance of ultraviolet light is hindered by the absorption of ultraviolet light by the organic compound contained in the composition and the coating film does not cure. Further, as an example of performing a polymerization reaction using visible light having a wavelength longer than ultraviolet light, near infrared light, etc., irradiation with visible light, near infrared light, etc. by using a light-absorbing dye and a boron-based compound Example in which photo-curing is possible by
2-143044, JP-A-2-4804, etc.), but all of them use soluble dyes, that is, organic dyes such as cyanine dyes, aniline dyes, rhodamine dyes, etc. There is a problem and it cannot be said that the method is sufficient in terms of versatility, and no photopolymerizable composition containing an insoluble pigment has been known at all.

[0005]

DISCLOSURE OF THE INVENTION The present invention is capable of polymerizing a composition containing a pigment, which has been difficult by conventional photopolymerization. It is an object of the present invention to provide a polymerization initiator and a photopolymerizable composition by combining a light absorbing pigment.

[0006]

That is, according to the present invention, a tetraalkylboron compound represented by the general formula (1), a general formula (1);

[0007]

[Chemical 2] A photopolymerization initiator can be obtained by combining the compound and a light absorbing pigment, and a photopolymerizable composition can be obtained by further adding a polymerizable unsaturated compound.

[0008]

[Chemical 3] A quaternary ammonium cation or a quaternary pyridinium cation, a quaternary quinolinium cation, a phosphonium cation, an alkali metal ion such as sodium, potassium and lithium, a metal cation such as an alkaline earth metal ion such as magnesium and calcium Ion and the like,

Specific examples of the boron compound which is the initiator of the present invention include monoalkyltriphenylboron (wherein the alkyl group is n-butyl group, n-octyl group, n-dodecyl group, naphthyl group, etc.). Sodium salt, potassium salt, lithium salt, magnesium salt, calcium salt, tetramethyl ammonium salt, tetraethyl ammonium salt, tetrabutyl ammonium salt, trimethyl hydrogen ammonium salt, triethyl hydrogen ammonium salt, tetrahydrogen ammonium salt, methyl pyridinium salt, ethyl pyri Dium salt,

Butylpyridinium salt, methylquinolinium salt, ethylquinolinium salt, butylquinolinium salt,
Sodium salt, potassium salt, lithium salt, magnesium salt, calcium salt, tetramethylammonium salt, tetraethylammonium salt, tetrabutylammonium salt, trimethylhydrogenammonium salt, triethylhydrogen of monoalkyltrianisylboron (the alkyl group is the same as above). Ammonium salt, tetrahydrogen ammonium salt, methylpyridinium salt,

Ethylpyridinium salt, butylpyridinium salt, methylquinolinium salt, ethylquinolinium salt,
Butylquinolinium salt, sodium salt, potassium salt, lithium salt, magnesium salt, calcium salt, tetramethylammonium salt, tetraethylammonium salt, tetrabutylammonium salt, methylpyridinium salt of dialkyldiphenylboron (the alkyl group is the same as above) , Methylquinolinium salt,

Sodium salt, potassium salt, lithium salt, magnesium salt, calcium salt, tetramethylammonium salt, tetraethylammonium salt, tetrabutylammonium salt, methylpyridinium salt, methyl of dialkyldianisylboron (the alkyl group is the same as above). Quinolinium salt, sodium salt of tetraphenylboron, potassium salt, lithium salt, magnesium salt, calcium salt, tetramethylammonium salt, tetraethylammonium salt, tetrabutylammonium salt,

Tetraanisylboron sodium salt, lithium salt, tetramethylammonium salt, tetraethylammonium salt, tetrabutylammonium salt, tetra-n-butylboron sodium salt, lithium salt, magnesium salt, tetramethylammonium salt, tetraethylammonium salt Salt, tetrabutylammonium salt, methylpyridinium salt, ethylpyridinium salt, butylpyridinium salt, methylquinolinium salt,

Ethylquinolinium salt, butylquinolinium salt, tetra-n-butyl (triphenylsilyl) boron tetramethylammonium salt, tetraethylammonium salt, tetrabutylammonium salt, tri-n-butyl (dimethylphenylcinnyl) boron Tetramethylammonium salt, tetraethylammonium salt, tetrabutylammonium salt, tetramethylammonium salt of n-octyldiphenyl (di-n-butylphenylsilyl) boron, tetraethylammonium salt, tetrabutylammonium salt, dimethylphenyl (trimethylsilyl) boron , Tetramethylammonium salt, tetraethylammonium salt, tetrabutylammonium salt and the like. These boron compounds may be used alone or in combination of two or more.

The light-absorbing pigment in the present invention means that it does not dissolve in the composition and exists in a solid state.
A pigment that absorbs visible light or near infrared light. It is generally known that a coloring substance absorbs light having a wavelength having a color complementary to its color (for example, "Dye Chemistry" Kyoritsu Publishing Co., Ltd. 1985). That is, the yellow pigment absorbs the wavelength light of the complementary blue color (about 450 nm), and the red pigment absorbs the wavelength light of the blue green color (about 50 nm).

That is, coloring pigments other than metallic pigments such as aluminum that reflect light absorb light of wavelengths having a complementary color relationship. Further, it is known that titanium white (titanium oxide), which is a white pigment that does not absorb visible light, absorbs ultraviolet light (410 nm or less) and functions as a semiconductor photocatalyst (for example, “Modern Chemistry”, January 1981, 52).
page). Specific examples of these light-absorbing pigments include black pigments such as carbon black and titanium black as inorganic pigments, white pigments such as titanium white, and phthalocyanines such as phthalocyanine blue and phthalocyanine green which are condensed polycyclic pigments as organic pigments. Pigments, quinacridone,

Thioindigo, isoindolinone, dioxazine, perylene, phthaloperinone, quinophthalone, etc.
Azo pigments, β-naphthol pigments (Table 1-1), pyrazolone pigments (Table 1-2), acetoacetic acid allylide pigments
(Table 1-3), anthrapyrimidine which is a quinone pigment,
Anthraquinone pigments such as indanthrene, flavantron, pyrantrone, iobiolantrone,
2-dihydroxy anthraquinone, 1,4-dihydroxy anthraquinone and the like can be mentioned. An example of the light absorbing pigment of the present invention is “Latest Pigment Dispersion Technology” published by Technical Information Association (199
3 years), "Functional pigment application technology" published by CMC (issued in 1991), etc.

[0018]

[Table 1]

Conventionally, photopolymerization initiators in which a boron compound and a cationic dye are combined are known, but those cationic dyes are limited to solvent-soluble dyes, and the stability of the dye remaining in the polymer and the stability of the hue are stable. However, there was a problem in the storage stability of the polymer itself and the storage stability of the polymer itself. Further, no example has been known in which an insoluble pigment dye is used as a photopolymerization initiator in combination with a boron compound.

As a result of intensive investigations by the present inventors regarding a polymerization initiator containing a pigment, surprisingly, in the presence of a polymerizable unsaturated compound, a specific boron compound was not dissolved in the polymerization system. The present invention was completed by finding that a polymer having a fastness was obtained by combining a solid pigment and irradiating light having a wavelength in the spectral range in which the pigment can be absorbed to obtain a polymer having excellent fastness. Came to do. It was difficult to photo-cure the pigmented composition due to insufficient light transmission in conventional ultraviolet light curing, but the photo-polymerizable composition of the present invention has a long wavelength visible light, near red light. Since external light or the like can be used, it is possible to polymerize even in a polymerization system to which a pigment is added.

Pigments that have been added for improving the cosmetic properties, fastness, hiding power, or the like of conventional compositions or for coloring are considered as light-absorbing compounds, and are made to function as an essential requirement for photopolymerization initiators. There is a great feature of the present invention. The light used in the present invention is appropriately selected according to the absorption wavelength of the light absorbing pigment, and the light source may be a mercury lamp, a metal halide lamp, a halogen lamp, a xenon lamp or the like. In order to increase the efficiency of the polymerization reaction, it is important to select a light source having a spectrum that matches the maximum absorption of the light absorbing pigment.

Although the mechanism of initiation of polymerization is not always clear, in the case of organic pigments such as phthalocyanine,
It is considered that electron transfer occurs from the coexisting boron compound to the pigment molecule excited by the absorbed light energy, and further the alkyl (or aryl) radical is cleaved from the boron compound which becomes a radical by one electron transfer to function as a polymerization initiation species. To be In the case of inorganic pigments such as titanium white (titanium oxide), charge separation occurs on the pigment surface that has absorbed light energy (electrons and holes),
After that, it is considered that the electron transfer from the boron compound occurs in the same manner as in the case of the organic pigment to generate the polymerization initiation species.

The polymerizable unsaturated compound used in the present invention is a polymerizable unsaturated monomer, a polymerizable unsaturated oligomer, or a polymer, or a mixture thereof, and is disclosed in, for example, JP-A-4-362935 and Japanese Patent Application No. 4-362935. 17576
Those described in No. 7 specification can be mentioned. These polymerizable monomers, oligomers, polymers and the like can be used alone or in admixture of two or more.

Examples of the polymerizable unsaturated monomer include
An esterified product of (meth) acrylic acid and a 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, methylenebisacrylamide and other (meth) acrylic compounds, vinyl acetate, vinyl propionate, vinyl benzoate and other vinyl esters, allyl alcohol, allyl acetate, diallyl phthalate and other allyl groups The monomer etc. which are contained are mentioned. Furthermore, as the monomer, 2-hydroxyethyl
(Meth) acrylate, 2-hydroxypropyl (meth)
Hydroxyl group-containing monomers such as acrylates; Addition products of polyisocyanates such as butyl isocyanate and phenyl isocyanate with the above hydroxyl group-containing monomers; Addition products of phosphoric acid and the above hydroxyl group-containing monomers; N-vinylpyrrolidone, N-vinylcarbazole, N- Nitrogen-containing unsaturated monomers such as vinylacetamide and vinylpyridines can also be used.

Further, as the monomer, a di-, tri- or tetravinyl compound such as diethylene glycol diacrylate, 1,6-hexanediol dimethacrylate, trimethylolpropane triacrylate, pentaerythritol trimethacrylate or pentaerythritol tetraacrylate; A product obtained by reacting an adduct of a polyhydric alcohol with ethylene oxide with acrylic acid and / or methacrylic acid; a product obtained by reacting the adduct of a polyhydric alcohol with propylene oxide with acrylic acid and / or methacrylic acid A product obtained by reacting acrylic acid and / or methacrylic acid with an adduct of the above polyhydric alcohol and ε-caprolactone; a phosphorus-containing polymerizable unsaturated monomer and the like are included,

Specific examples of the polymerizable unsaturated polymer include a resin obtained by condensation of polyester (meth) acrylic acid, an ethylenically unsaturated group-containing polyurethane resin, an ethylenically unsaturated group-containing epoxy resin, and an ethylenically unsaturated group. Examples thereof include phosphorus-containing epoxy resin, ethylenically unsaturated group-containing acrylic resin, ethylenically unsaturated group-containing silicone resin, ethylenically unsaturated group-containing melamine resin and the like. In particular, the (meth) acrylic functional polyorganosilsesquioxane disclosed in JP-A-4-28722 is suitable.

In the photopolymerizable composition of the present invention, in addition to the light absorbing pigment forming the photopolymerization initiator, any pigment, coloring dye or the like can be added. Specific examples include various commercially available pigments including metal pigments such as aluminum powder, aluminum paste, gold powder, and silver powder, as well as various documents (eg, “Handbook of Dyes” edited by the Society of Synthetic Organic Chemistry, Showa 4).
The publicly known ones described in "The latest pigment handbook" edited by Japan Pigment Technology Association, published in 1976) can be used.

It is also possible to add a conventionally known light absorbing dye such as a cyanine dye or a rhodamine dye to the polymerization initiator and the photopolymerizable composition of the present invention to enhance the light absorption efficiency and increase the polymerization rate. It is possible. The rate of polymerization can also be increased by heating. Further, the polymerization reaction may be carried out under an atmosphere of an inert gas such as nitrogen or under reduced pressure for the purpose of preventing polymerization inhibition by oxygen in the air.

Further, the photopolymerizable composition of the present invention may contain any additives, fillers and the like within a range not departing from the gist of the present invention. Examples of the additive here include thickeners, leveling agents, thixotropic agents, dispersants,
Examples include plasticizers, antioxidants, UV inhibitors, lubricants and the like, and examples of the filler include organic substances, inorganic substances, or their composites and mixtures. Examples of the organic filler include those obtained by finely pulverizing a polymer,
Further, as the inorganic filler, silica, silica-alumina, alumina, quartz, glass, calcium carbonate, kaolin, talc, mica, aluminum sulfate, valium sulfate,
Examples thereof include powders of calcium sulfate, calcium phosphate and the like, and those obtained by coating the surfaces of the powders with a polyfunctional (meth) acrylate monomer or a silane coupling agent. Examples of the composite include those obtained by mixing the above-mentioned inorganic filler with an ethylenically unsaturated compound, polymerizing and curing it, and then finely pulverizing it. Further, two or more different kinds of fillers may be added separately, or may be added after mixing, without any problem.

The object of the present invention can be achieved by using the boron compound represented by the general formula (1) in the present invention in an amount of 0.001 weight% or more of the curable compound. If it is less than that, the polymerization may not be sufficiently performed, and the curing may be insufficiently completed. The preferred range is 0.01 to 10% by weight. It is not preferable from the economical point of view to use too much. Further, the light absorbing pigment of the present invention can be added in an arbitrary amount, generally 0.1% by weight or more based on the whole composition.

The polymerizable composition of the present invention can be used as a solventless curable composition and is expected to contribute to the improvement of the global environment. Of course, it may be used in a form diluted with a conventional solvent. Examples of the solvent that can be used at that time include general solvents used for conventional paints, such as aromatic hydrocarbons such as toluene and xylene, aliphatic hydrocarbons such as heptane, hexane, and pentane, acetone, and methyl ethyl ketone. , Ketones such as 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 ethylene glycol monoethers such as methyl cellosolve and ethyl cellosolve can be used. These solvents are 1
One kind or a mixture of two or more kinds can be used. These solvents also have a function of adjusting the viscosity of the material, compatibility of the composition, improvement of workability, etc., so that an appropriate amount can be added depending on the situation.

[0032]

EXAMPLES The present invention will be described below with reference to examples. Curing in the evaluation of the cured product means a state in which the surface of the coating film after curing and the inner surface of the coating film damaged by the cutter knife are visually observed and touched by hand, and there is no tackiness or tack at all.

Example 1 10 g of pentaerythritol triacrylate, 2 g of titanium white (Taipaque CR-90 manufactured by Ishihara Sangyo Co., Ltd.) and 0.1 g of tetrabutylammonium n-butyltriphenylboron were thoroughly mixed, and sample 1 was prepared. And

Example 2 Sample 2 was prepared in the same manner as in Example 1 except that triethylene glycol diacrylate was used instead of pentaerythritol triacrylate.

Example 3 Sample 3 was prepared in the same manner as in Example 1 except that carbon black (trade name: Printex95 manufactured by Degussa Co.) was used instead of titanium white.

Example 4 Sample 4 was prepared in the same manner as in Example 1 except that phthalocyanine blue (trade name L-7072D manufactured by BASF) was used in place of titanium white.

Example 5 Instead of titanium white, a red pigment (trade name Lionol Red 7BFC-4417 manufactured by Toyo Ink Co., Ltd.) was used.
Sample 5 was prepared in the same manner as in Example 1 except that (X) was used.

Example 6 Tetrabutylammonium n
Sample 6 was synthesized in the same manner as in Example 1 except that ethylpyridinium n-butyltriphenylboron was used instead of -butyltriphenylboron.

Example 7 Tetrabutylammonium n
Sample 7 was prepared in the same manner as in Example 1 except that tetrabutylammonium di-n-butyldiphenylboron was used instead of -butyltriphenylboron.

Comparative Example 1 Tetrabutylammonium n
Sample a was prepared in the same manner as in Example 1 except that -butyltriphenylboron was not added.

(Comparative Example 2) Sample b was prepared in the same manner as in Example 1 except that titanium white was not added.

[Curing Test 1] A sample prepared with the above composition was applied to an aluminum plate of 2.5 × 7.0 cm to a thickness of 250 μm. The test piece thus obtained was irradiated with a halogen lamp with an output of 1500 W having a spectral distribution in the wavelength range of 800 nm to 950 nm for 5 minutes in a nitrogen atmosphere. All the samples of the examples were cured, but the samples of comparative examples a and b were not cured and remained liquid.

(Example 8) A mixture (Sample 1) having the same composition as in Example 1 was diluted with an equal amount of toluene, and the composition was spray-coated on the steel sheet so that the composition would be deposited at 50 g / m ² . After drying this sample at 80 ° C. for 30 minutes, it was irradiated with a halogen lamp as in the curing test 1. The sample was cured.

[0044]

The present invention provides a polymerization initiator and a photopolymerizable composition capable of polymerizing a composition containing a pigment which has been difficult to photopolymerize in the past.

Claims (3)

[Claims] 1. A photopolymerization initiator comprising a boron compound represented by the general formula (1) and a light absorbing pigment. General formula (1); 2. The photopolymerization initiation according to claim 1, wherein the light absorbing pigment is one selected from condensed polycyclic pigments, azo pigments, quinone pigments, anthraquinone pigments, carbon black and titanium white. Agent. 3. A photopolymerizable composition comprising a polymerizable unsaturated compound, a boron compound represented by the general formula (1) according to claim 1 and a light absorbing pigment.