JP2023025375A - Photocationic curable composition - Google Patents

Abstract

[Problem] To provide a photocationically curable composition which cures quickly under room temperature conditions and further produces little coloring during curing. [Solution] In a photocationically curable composition containing (a) a cationic polymerizable monomer and (b) a photocationic initiator, the cationic polymerizable monomer (a) is constituted by a specific cationic polymerizable monomer consisting of a compound having in its molecule a partial structure in which a carbonyl group is bonded to an epoxy ring or an oxacene ring via a divalent group having 1 to 3 atoms in the main chain, and a non-specific cationic polymerizable monomer other than the specific cationic polymerizable monomer, and the content of the specific cationic polymerizable monomer based on the total mass of the cationic polymerizable monomer (a) is 1 to 25 mass%. [Selected Figure] None

Description

The present invention relates to photocationically curable compositions. More particularly, it relates to a composition that rapidly photocures and causes little coloration during curing.

In recent years, photocurable resin compositions have been widely used for adhesion of electric/electronic parts, paints, and the like. A photocurable resin composition cures more quickly than heat-curable adhesives. It has many advantages, such as the setting of working time up to curing is arbitrary, and there is no volatilization of solvent or the like during curing.

Photo-curable resin compositions are broadly classified into radical polymerization type and cationic polymerization type, but mainly radical polymerization type using a (meth)acrylic polymerizable compound with good curability. has been developed and used in

Photocurable resin compositions are also used for dental applications. Examples include light-curable filling and restorative materials called composite resins used to restore teeth damaged by caries, fractures, etc., denture base lining materials, and hybrid ceramics for crown restoration. It is widely used due to its ease of operation. Such photocurable dental materials usually consist of a polymerizable monomer and a polymerization initiator, and composite resins and hybrid ceramics contain fillers. As the polymerizable monomer, a (meth)acrylate radically polymerizable monomer is used because of its good photopolymerizability.

However, (meth)acrylate-based radically polymerizable monomers have a problem of large polymerization shrinkage. That is, when a filling restorative material such as a composite resin is filled into a tooth cavity requiring restoration and then polymerized and cured, the surface of the filled restorative material is irradiated with light, but shrinkage due to polymerization occurs. As a result, a stress is exerted that tends to detach from the interface of the tooth, which tends to create a gap between the tooth and the filling restorative material.

In order to solve such problems, cationically curable dental compositions using cationically polymerizable monomers such as epoxy compounds and oxetane compounds with small polymerization shrinkage have been proposed. For example, in Patent Document 1, as a photopolymerizable composition with high sensitivity in the entire "visible light" region, "(a) a cationically polymerizable resin; and (b) a photoinitiator for the cationically polymerizable resin (ii) a visible light sensitizer; and (iii) a 1,4- an electron donor compound having an oxidation potential lower than that of dimethoxybenzene, wherein said photoinitiator system comprises 2.9×10 ⁻⁵ mol/g of hexafluoroantimonic acid in 2-butanone; A photopolymerizable composition having a photo-induced potential lower than that of 3-dimethylaminobenzoic acid in a standard solution containing diphenyliodonium and 1.5×10 ⁻⁵ mol/g of camphorquinone.” is described.

In addition, Patent Document 2 describes a dental curable composition that exhibits extremely small polymerization shrinkage, is free from polymerization inhibition by oxygen, cures in the oral cavity in a short time, and is less likely to be polymerized by water, as "(I) A cationically curable dental composition comprising a cationic polymerization initiator and (II) a cationically polymerizable monomer, wherein the (II) cationically polymerizable monomer has at least one oxetane functional group in its molecule and an epoxy compound having at least one epoxy functional group in the molecule, wherein the amount of the oxetane compound in the mixture is A moles, the amount of the epoxy compound is B moles, and the oxetane compound When the average number of oxetane functional groups per molecule is a and the number of epoxy functional groups per molecule average of the epoxy compound is b, (a × A): (b × B) is 90: A cationically curable dental composition characterized in that it is a mixture in the range of 10-45:55. Also in Patent Document 2, (I) as cationic polymerization initiators, diaryliodonium salt-based compounds, sulfonium salt-based compounds, and compounds having absorption in the near-ultraviolet to visible region from the viewpoint of exhibiting high polymerization activity with visible light. It is preferable to combine with a sensitizer consisting of, and it is preferable to further blend an oxidative photoradical generator.

Japanese Patent Publication No. 2005-523348 JP 2006-008635 A

By the way, when the photo-cationically curable composition is used for dental purposes, its color tone is also an important factor. In general, when a dental material is used for restorative treatment, it is desired that the treated area be inconspicuous, and therefore the dental material needs to exhibit a color close to that of natural teeth after hardening. In the case of a composition whose color tone changes before and after curing, it is difficult to adjust the color tone after curing, so it is desired that the color tone change is small during curing. However, according to the studies of the present inventors, when the above-described photo-cationically polymerizable composition was used, the cured product was sometimes colored.

Accordingly, an object of the present invention is to provide a photo-cationically curable composition that causes little change in color tone upon curing.

The present invention is intended to solve the above problems, and the first form of the present invention is a photocationically curable composition containing (a) a cationic polymerizable monomer and (b) a photocationic initiator,
The (a) cationically polymerizable monomer has the following formula

(In the above formula, * represents a point of attachment to the rest of the molecule, X represents a divalent group having 1 to 3 atoms in the main chain, Y represents a bond or a methylene group, R ¹ represents a hydrogen atom or a hydrocarbyl group having 1 to 12 carbon atoms.)
Consists of a specific cationically polymerizable monomer consisting of a compound containing a partial structure represented by and a non-specific cationically polymerizable monomer other than the specific cationically polymerizable monomer,
The content of the specific cationically polymerizable monomer based on the total weight of the (a) cationically polymerizable monomer is 1 to 25% by mass,
The photo cationic curable composition is characterized by:

In the above-described photocationically curable composition (hereinafter also referred to as "the photocationically curable composition of the present invention"), the (b) photocationic initiator comprises a photoacid generator and a photosensitizer. and / or an electron-donating compound, particularly the photoacid generator is an iodonium salt compound, the photosensitizer is an α-diketone compound, and the electron-donating compound is a polycyclic aromatic compound and / or preferably a thiophene compound. Moreover, it is preferable that the non-specific cationically polymerizable monomer comprises an epoxy compound and/or an oxetane compound.

A second aspect of the present invention is a dental curable composition comprising the photo-cationically curable composition of the present invention.

It is preferable that the dental hardenable composition of the above form (hereinafter also referred to as "the dental hardenable composition of the present invention") further contains a filler.

The photocationically curable composition of the present invention not only has the features of a photocationically curable composition containing a cationic polymerizable monomer and a photocationic polymerization initiator, which are characterized by small polymerization shrinkage, but also It has the property of being capable of rapid curing and having little change in color tone during curing.

In addition, the dental curable composition of the present invention has significantly reduced polymerization shrinkage as compared with radically polymerizable compositions used in general dental materials, and also cures rapidly even at room temperature. , little change in color tone upon curing. Therefore, it can be said that it is particularly suitable for use as a dental restorative material such as a composite resin.

As described above, in conventional general photo-cationic dental curable compositions, the cured product may be colored. The present inventors believe that the cause of such coloration is the rapid heat generation due to the use of a highly active polymerization initiator. Coloration was reduced when an amine compound that inhibits cationic polymerization was added. Therefore, the inventors have made intensive studies on methods for suppressing heat generation without lowering the curing speed. As a result, by making some of the cationic polymerizable monomers into polymerizable monomers with a specific partial structure, it is possible to achieve rapid curing at room temperature, and photo-cationic curing with little change in color tone during curing. The inventors have found that it can be a composition, and have completed the present invention.

Although the present invention is not bound by any logic, the inventors of the present invention presume that the mechanism by which the above effects are obtained is as follows. That is, the specific cationically polymerizable monomer containing the partial structure is nucleophilic due to an intramolecular carbonyl group as shown in the following formula (known as adjacent group participation) during the reaction with the cation. Polymerization is thought to proceed via cationic species (having cationic polymerization ability) generated by the reaction.

At this time, since the number of atoms in the main chain of X is any one of 1 to 3, the generated cation has a relatively stable 5- to 7-membered ring structure, and the rate of cationic polymerization decreases. By including the specific cationically polymerizable monomer having such properties, the effect is exhibited even if the amount is not so large, for example, about 1% by mass. This is because the amount of H ⁺ generated by the photocationic initiator is small (e.g., 1%) relative to the substance amount of the polymerizable monomer. is likely to pass through this reaction system. It is thought that local heat generation due to rapid cationic polymerization was suppressed, and coloration during curing was reduced because the reaction would be slowed down at that stage if it was passed through even once. On the other hand, with respect to polymerizability, unlike the case where cationic species are captured by a basic substance, the generated cationic species are active, and the content of specific cationic polymerizable monomers is also limited. It is presumed that the rapid curability was maintained even in the state.

In addition, as shown in Comparative Examples described later, when using a cationic polymerizable monomer having no structure in which a cyclic ether moiety and a carbonyl group are adjacent (for example, Comparative Example 1), or when having such a structure Coloring cannot be prevented if a cationic species having a 5- to 7-membered ring structure stabilized by the participation of adjacent groups is not generated (Comparative Example 3).

Thus, the main feature of the cationic photocurable composition of the present invention is that (a) the cationic polymerizable monomer contains 1 to 25% by mass of the specific cationic polymerizable monomer. It is in. Each component constituting the photo-cationically curable composition of the present invention, including the specific cationically polymerizable monomer, will be described below.

1. (a) Cationic polymerizable monomer In the composition of the present invention, the polymerizable component (a) cationic polymerizable monomer is a compound polymerized by active species generated by decomposition of the photocationic initiator. Since the above-mentioned photocationic initiator generates acid and radicals by decomposition, compounds having a cationically polymerizable functional group and/or a radically polymerizable functional group that are polymerized by an acid are applicable. Hereinafter, the (a) cationically polymerizable monomer is classified into a specific cationically polymerizable monomer and a non-specific cationically polymerizable monomer for explanation.

(1) Specific cationically polymerizable monomer The specific cationically polymerizable monomer means a cationically polymerizable monomer comprising a compound having a partial structure represented by the following formula in the molecule.

Here, * in the formula represents the point of attachment to other parts of the molecule. Also, X represents a divalent group having a main chain of 1 to 3 atoms. Examples of groups suitable for X include -O-, -C-O-, -C-O-C-, etc. Among them, 6, which is easily available and particularly stable in reaction with cationic species, -C-O- is preferred because it can form a membered ring. Y represents a bond or a methylene group: —CH ₂ —, and when Y is a bond, it forms an epoxy ring, and when it is a methylene group, it forms an oxacene ring. R ¹ represents a hydrogen atom or a hydrocarbyl group having 1 to 12 carbon atoms. Suitable examples of hydrocarbyl groups having 1 to 12 carbon atoms include methyl group, ethyl group, propyl group, isopropyl group, vinyl group, allyl group, phenyl group, etc., and they are said to be readily available. For this reason, it is preferably a methyl group or an ethyl group.

The specific cationically polymerizable monomer is not particularly limited as long as it is a compound having the above partial structure and exhibiting cationic polymerizability, and has a radically polymerizable functional group such as a vinyl group, an acryloyl group, or a methacryloyl group. may be However, from the viewpoint of not inhibiting cationic polymerization, it is preferable not to have a basic site such as an amine site.

Specific examples of specific cationic polymerizable monomers that can be preferably used include glycidyl acetate, glycidyl benzoate, glycidyl acrylate, glycidyl methacrylate, diglycidyl glutarate, diglycidyl 1,2-cyclohexanedicarboxylate, (3-ethyl Oxetan-3-yl)methyl acetate, (3-ethyloxetan-3-yl)methyl acrylate, (3-ethyloxetan-3-yl)methyl methacrylate, bis[(3-ethyl-3-oxetanyl)methyl]isophthalate , bis[(3-ethyl-3-oxetanyl)methyl]terephthalate, and the like.

These specific cationic polymerizable monomers may be used alone or in combination of two or more.

In order to obtain the effect of the present invention, it is necessary that 1 to 25% by mass of the total mass of the cationic polymerizable monomer (a) is composed of the specific cationic polymerizable monomer. (a) If the content of the specific cationically polymerizable monomer in the cationically polymerizable monomer is less than 1% by mass, a sufficient adhesion prevention effect cannot be obtained, and the content is less than 25% by mass. If it exceeds, sufficient curability cannot be obtained. From the viewpoint of ensuring sufficient curability and obtaining a high anti-coloring effect, the content of the specific cationically polymerizable monomer is preferably 2 to 20% by mass, more preferably 5 to 15% by mass. is particularly preferred.

(2) Non-specific cationically polymerizable monomer A non-specific cationically polymerizable monomer means a cationically polymerizable monomer composed of a compound other than the specific cationically polymerizable monomer. In addition, the non-specific cationically polymerizable monomer accounts for the remainder other than the specific cationically polymerizable monomer in (a) the cationically polymerizable monomer, and the total amount of the (a) cationically polymerizable monomer The content based on mass is 100% by mass minus the content of non-specific cationic polymerizable monomer (% by mass).

Examples of non-specific cationic polymerizable monomers include cations such as epoxy compounds, oxetane compounds, cyclic ether compounds, vinyl ether compounds, bicyclic orthoester compounds, cyclic acetal compounds, bicyclic acetal compounds, and cyclic carbonate compounds that satisfy the above conditions. Polymerizable monomers can be used without any particular limitation. Epoxy compounds and/or oxetane compounds are preferably used from the viewpoints of easy availability, small volume shrinkage, and rapid polymerization reaction. However, from the viewpoint of not inhibiting cationic polymerization, it is preferable not to have a basic site such as an amine site.

Specific examples of epoxy compounds that can be suitably used as non-specific cationic polymerizable monomers include 1,2-epoxypropane, methylglyzidyl ether, cyclohexene oxide, exo-2,3-epoxynorbornene, and 4-vinyl. -Those having one epoxy functional group such as 1-cyclohexene-1,2-epoxide, limonene oxide, α-pinene oxide, styrene oxide, (2,3-epoxypropyl)benzene, phenylglycidyl ether; 1,3- Butadiene dioxide, ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, triethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, diglycidyl glutarate, 4-vinyl-1-cyclohexene diepoxide, limonene diepoxide , compounds having two epoxy functional groups such as methylbis[2-(7-oxabicyclo[4.1.0]hept-3-yl)ethyl]phenylsilane; glycerol triglycidyl ether, trimethylolpropane triglycidyl ether, Those having three or more epoxy functional groups such as pentaerythritol triglycidyl ether, pentaerythritol tetraglycidyl ether, dipentaerythritol hexaglycidyl ether, etc., compounds with cyclic siloxane and silsesquioxane structures such as the compounds shown below, and epoxy those having a functional group, and the like.

In the following structural formulas (excluding structural formulas specifying R), the bond marked with *1 indicates that it is bonded to the O atom of the adjacent repeating structural unit, and the bond marked with *2 A hand indicates a bond with the Si atom of the adjacent repeating unit.

Specific examples of oxetane compounds that can be suitably used as non-specific cationic polymerizable monomers include trimethylene oxide, 3-methyl-3-oxetanylmethanol, 3-ethyl-3-oxetanylmethanol, 3-ethyl -Compounds having one oxetane ring such as 3-phenoxymethyloxetane, 3,3-diethyloxetane, 3-ethyl-3-(2-ethylhexyloxy)oxetane; 1,4-bis(3-ethyl-3-oxetanyl) methyloxy)benzene, 4,4'-bis(3-ethyl-3-oxetanylmethyloxy)biphenyl, 4,4'-bis(3-ethyl-3-oxetanylmethyloxymethyl)biphenyl, ethylene glycol bis(3- Ethyl-3-oxetanylmethyl) ether, diethylene glycol bis(3-ethyl-3-oxetanylmethyl) ether, and compounds having two or more oxetane rings such as the compounds shown below can be mentioned.

In the structural formulas shown below, the bond marked with *1 in the structural formula on the left side of the bottom row indicates that it is bonded to the O atom of the adjacent repeating structural unit, and the bond marked with *2 is It indicates that it is bonded to the Si atom of the adjacent repeating structural unit.

2. (b) Photocationic Initiator (1) Photoacid Generator In the composition of the present invention, the (b) photocationic initiator is not particularly limited as long as it is a compound that produces a strong acid by a reaction caused by light irradiation. Salt compounds, sulfonium salt compounds, bismuthonium salt compounds, pyridinium salt compounds, and the like, which are used as photoacid generators in conventional photocationically curable compositions, can be used without particular limitation. It is preferable to use iodonium salt compounds because they are readily available and have high polymerization activity. Also, the (b) photocationic initiator may be used alone or in combination of two or more as needed.

Specific examples of (b) photocationic initiators that are preferably used include onium salt compounds having the following cations and anions.

[Cation]
Diphenyliodonium, bis(p-chlorophenyl)iodonium, ditolyliodonium, bis(p-tert-butylphenyl)iodonium, p-isopropylphenyl-p-methylphenyliodonium, bis(m-nitrophenyl)iodonium, p-tert- Butylphenylphenyliodonium, p-methoxyphenylphenyliodonium, bis(p-methoxyphenyl)iodonium, p-octyloxyphenylphenyliodonium, p-phenoxyphenylphenyliodonium, bis(p-dodecylphenyl)iodonium, triphenylsulfonium, tri tolylsulfonium, p-tert-butylphenyldiphenylsulfonium, diphenyl-4-phenylthiophenylsulfonium, diphenyl-2,4,6-trimethylphenylsulfonium, tetraphenylbismutonium, triphenyl-2,4,6-trimethylphenyl bismuthonium, 1-methylpyridinium, 1-methyl-2-chloropyridinium and the like.

[Anion]
tetrakispentafluorophenylborate, tetra(nonafluoro-tert-butoxy)aluminate, hexafluorophosphate, hexafluoroantimonate, hexafluoroarsenate, tetrafluoroborate, trifluoromethanesulfonate, perchlorate and the like.

(b) The amount of the photocationic initiator used is not particularly limited as long as it is an amount that can initiate polymerization by light irradiation, but an appropriate rate of progress of polymerization and various physical properties of the resulting cured product (e.g., In order to achieve both weather resistance and hardness), it is generally sufficient to use 0.01 to 20 parts by mass, preferably 0.05 to It is preferable to use 10 parts by mass.

(b) The photocationic initiator preferably contains a photosensitizer and/or an electron-donating compound because the photocationic initiator has high polymerization activity and the effect of the present invention (especially the effect of preventing coloration) is remarkable.

(2) Photosensitizer The photosensitizer is not particularly limited as long as it absorbs light energy and accelerates the decomposition of the photoacid generator. Ketone compounds (especially α-diketone compounds), coumarin dyes , cyanine-based dyes, merocyanine-based dyes, thiazine-based dyes, azine-based dyes, acridine-based dyes, xanthene-based dyes, squalium-based dyes, pyrylium salt-based dyes, and the like can be used. Among these, camphorquinone, benzyl, diacetyl, acetylbenzoyl, 2,3-pentadione, 2,3-octadione, 4,4'-dimethoxybenzyl, and 4,4'-oxybenzyl are used because they suppress the coloring of the cured product. , 9,10-phenanthrenequinone, acenaphthenequinone and the like are preferably used, and camphorquinone is particularly preferably used.

The photosensitizers described above may be used singly or in combination of two or more as needed. The amount of the photosensitizer used varies depending on the other components to be combined and the type of the polymerizable monomer, but usually 0.001 to 10 parts by weight per 100 parts by weight of the cationic polymerizable monomer (a). Any amount may be used, preferably 0.01 to 5 parts by mass.

(3) Electron donating compound The electron donating compound is not particularly limited as long as it improves the efficiency of generating cationic species, and aromatic amines, polycyclic aromatic compounds, thiophene compounds, etc. can be used. . However, from the viewpoint of cationic polymerization reaction rate, it is preferable to use a polycyclic aromatic compound and/or a thiophene compound.

Specific examples of polycyclic aromatic compounds that can be suitably used include 9,10-dimethylanthracene, 2-ethyl-9,10-dimethoxyanthracene, 9,10-dibutoxyanthracene, 1,8-dimethylphenanthrene, 7,12-dimethylbenz (a) anthracene and the like.

Specific examples of thiophene compounds that can be preferably used include 2,5-diphenylthiophene, 2,3,4,5-tetraphenylthiophene, 2,2′-bithiophene, and 5-hexyl-2,2′-bithiophene. , 5-octyl-2,2′-bithiophene, 3,3′-dihexyl-2,2′-bithiophene, 4,4′-dihexyl-2,2′-bithiophene, 5,5′-dihexyl-2,2 '-bithiophene, 2,2':5',2''-terthiophene, 5,5''-dibromo-2,2':5',2''-terthiophene, 4H-cyclopenta[2,1- b:3,4-b']dithiophene, dithieno[3,2-b:2',3'-d]thiophene, and the like.

The electron-donating compounds described above may be used singly or in combination of two or more as needed. The amount of the electron-donating compound used varies depending on the other components to be combined and the type of the polymerizable monomer. Well, preferably 0.01 to 5 parts by mass is used.

3. Other components In the photo-cationically curable composition of the present invention, (a) a cationic polymerizable monomer and (b ) “Other components” other than the photocationic initiator may be included. "Other components" will be described below.

(1) Radically polymerizable monomer As described above, the photocationic initiator used in the present invention simultaneously generates radical species, so that the polymerization of the radically polymerizable monomer also proceeds at the same time. From the viewpoint of polymerization rate, the photocationically curable composition of the present invention preferably uses a radically polymerizable monomer, particularly a radically polymerizable monomer having a meth(acryloyl) group as a radically polymerizable functional group. is.

Specific examples of radically polymerizable monomers that can be preferably used include methyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, 2-hydroxyethyl (meth) acrylate, ethylene glycol di (meth) acrylate, and diethylene glycol. di(meth)acrylate, triethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 2,2 - bis(4-methacryloyloxyphenyl)propane, 2,2-bis(4-methacryloyloxypolyethoxyphenyl)propane, 2,2-bis[4-(2-hydroxy-3-methacryloyloxypropoxy)phenyl]propane, trimethylolpropane trimethacrylate and the like.

The radically polymerizable monomers described above may be used singly or in combination of two or more as needed. However, from the viewpoint of keeping the polymerization shrinkage rate low, the amount of the radically polymerizable monomer used is preferably 25 parts by mass or less with respect to 100 parts by mass of the cationic polymerizable monomer (a), and is preferably 15 parts by mass. Part or less is more preferable.

(2) Filler When the photo-cationically curable composition of the present invention is used as a dental filling and restorative material, it is preferable to incorporate a filler.

As the filler, any of organic, inorganic or organic-inorganic composite fillers that are blended in dental filling and restorative materials can be blended. Examples of organic fillers include polymethyl methacrylate, polyethyl methacrylate, Methyl methacrylate-ethyl methacrylate copolymer, crosslinked polymethyl methacrylate, crosslinked polyethyl methacrylate, ethylene-vinyl acetate copolymer, styrene-butadiene copolymer, acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer Particles composed of organic macromolecules, such as coalescence, can be mentioned.

Specific examples of inorganic fillers include inorganic particles such as quartz, silica, alumina, silica titania, silica zirconia, lanthanum glass, barium glass, and strontium glass. Examples of the organic-inorganic composite filler include granular organic-inorganic composite particles obtained by mixing these inorganic particles and a polymerizable monomer in advance, forming a paste, polymerizing the paste, and pulverizing the paste. X-ray opacity can be imparted by using an inorganic filler containing a heavy metal such as zirconia.

The particle size and shape of these fillers are not particularly limited, and spherical or amorphous particles having an average particle size of 0.01 μm to 100 μm, which are generally used as dental materials, may be appropriately used depending on the purpose. Just do it. Also, the refractive index of these fillers is not particularly limited, and those in the range of 1.4 to 1.7, which fillers of general dental curable compositions have, can be used without limitation.

The amount of the above-mentioned filler to be added to the photocationically curable composition of the present invention is not particularly limited as long as the composition becomes a paste. Employing an inorganic and/or organic-inorganic composite filler, it is 50 to 1500 parts by mass, preferably 70 to 1000 parts by mass, relative to 100 parts by mass of the cationic polymerizable monomer (a). preferable.

Further, these fillers such as inorganic fillers and organic-inorganic composite fillers may be used alone, or plural kinds of fillers having different materials, particle diameters, shapes, etc. may be used in combination. When used as a dental filling and restorative material, it is particularly preferable to use an inorganic filler as the main material because of its excellent mechanical properties after curing.

(3) Various Additives Additives such as UV absorbers, dyes, antistatic agents, pigments, perfumes, organic solvents, and thickeners may be added to the cationic photocurable composition of the present invention.

4. A method for producing a cationic photocurable composition of the present invention The photocationically curable composition of the present invention comprises a cationic polymerizable monomer, a photoacid generator, It can be suitably produced by a method such as weighing a predetermined amount of other compounding ingredients that are blended as necessary and mixing them to form a paste. The photocationically curable composition of the present invention thus produced is stored in the dark until use.

5. Application and curing method of the photo-cationically curable composition of the present invention The photo-cationically curable composition of the present invention is not limited to dental applications, and can be used for adhesives, paints, etc., particularly dental filling and restorative materials. It is suitable as

As a means for curing the cationic photocurable composition of the present invention, a known polymerization means may be appropriately adopted according to the polymerization initiation mechanism of the photoacid generator type photopolymerization initiator used. Light irradiation by a light source such as arc, xenon lamp, metal halide lamp, tungsten lamp, fluorescent lamp, sunlight, helium cadmium laser, argon laser, or heating using a heat polymerization device, or a combination of these methods, etc. used without When polymerizing by light irradiation, the irradiation time varies depending on the wavelength and intensity of the light source, and the shape and material of the cured product. It is preferable to adjust the mixing ratio of the various components so that the time is in the range of about 5 to 60 seconds.

EXAMPLES The present invention will be specifically illustrated by examples below, but the present invention is not limited to these examples.

1. Abbreviations of Compounds Compounds used in Examples and Comparative Examples and their abbreviations are shown below.

(1) (a) Cationic Polymerizable Monomer [Specific Cationic Polymerizable Monomer]
・ EP-1: Glycidyl methacrylate (manufactured by Kyoei Co., Ltd.)
・ OX-1A: a compound represented by the following formula (manufactured by Osaka Organic Chemical Co., Ltd.)
· OX-1B: a compound represented by the following formula (manufactured by Ube Industries)

[Non-specific cationic polymerizable monomer]
・ EP-2A: a compound represented by the following formula (manufactured by Shin-Etsu Chemical Co., Ltd.)
・ EP-2B: a compound represented by the following formula (manufactured by Daicel)
· OX-2: a compound represented by the following formula (manufactured by Toagosei)

(2) Radically polymerizable monomer MA-A: a compound represented by the following formula (manufactured by Shin-Nakamura Chemical)

(3) (b) Photo cationic initiator [photoacid generator]
DPIB: iodonium salt with tetrakispentafluorophenylborate as a counter anion represented by the following formula (manufactured by Tokyo Chemical Industry Co., Ltd.)

[Photosensitizer]
・CQ: Camphorquinone (manufactured by Tokyo Chemical Industry Co., Ltd.)

[Electron donating compound]
・DMAn: 9,10-methyl-anthracene (manufactured by Tokyo Chemical Industry Co., Ltd.)
・ O-2T: 5-octyl-2,2′-bithiophene (manufactured by Tokyo Chemical Industry Co., Ltd.)
The structural formula of the electron-donating compound is shown below.

2. Examples and Comparative Examples Example 1
A cationic polymerizable unit consisting of 1 part by mass of OX-1A as a specific cationic polymerizable monomer, 60 parts by mass of EP-2A as a non-specific cationic polymerizable monomer, and 39 parts by mass of OX-2 A photo cationic initiator consisting of 1.0 parts by weight of DPIB, 0.2 parts by weight of CQ, and 0.05 parts by weight of DMAn is added to 100 parts by weight of the polymer, and stirred for 6 hours under red light. to prepare a photo-cationically curable composition.

The surface hardness, color and degree of coloring at curing of the resulting photo-cationically curable composition were evaluated by the following methods. Table 1 shows the results.

(1) Surface Hardness and Color of Cured Product The prepared photo-cationically curable composition was filled in a polyacetal mold having a hole of 7 mmφ×1.0 mm and pressed with a polypropylene film. Then, using a dental light irradiator (Tokuso Power Light, manufactured by Tokuyama Corporation), light irradiation was performed for 10 seconds (light intensity on irradiated surface: 800 mW/cm ² ). Immediately after the light irradiation, the state of the filling was checked to confirm whether or not the entire composition was cured. When the composition as a whole is cured, the obtained cured product is removed from the mold, and is subjected to a microhardness tester (MMT-X7 type, manufactured by Matsuzawa Seiki Co., Ltd.) using a Vickers indenter with a load of 100 gf and a load retention time of 30. The surface hardness was obtained from the diagonal length of the depressions formed in the test piece in seconds. Also, the color of the obtained cured product was visually evaluated.

(2) Degree of coloration during curing The prepared photo-cationically curable composition was filled in a polyacetal mold having holes of 7 mmφ×1.0 mm and pressed with a polypropylene film. The portion of the hole filled with the photo cationic curable composition was measured with a spectrocolorimeter (SE7700, manufactured by Nippon Denshoku Industries Co., Ltd.) with a white standard plate as a background (this measured value is referred to as "before curing color tone”). After completion of the color tone measurement, the photo-cationically curable composition was irradiated with light for 10 seconds using a dental light irradiator (Tokuso Power Light, manufactured by Tokuyama Corporation) (light intensity on the irradiated surface: 800 mW/cm ² ). . The photocurable composition immediately after light irradiation was measured in the same manner as the color tone before curing (this measured value is referred to as "color tone after curing"). The color difference ΔE ^* between the color tone before curing and the color tone after curing was taken as the value of the degree of coloring at the time of curing.

Examples 2-10 and Comparative Examples 1-6
A photo cationic curable composition was prepared in the same manner as in Example 1 except that the composition was changed as shown in Table 1, and the surface hardness, color and degree of coloring at curing of the cured body were prepared in the same manner as in Example 1. evaluated. The results are also shown in Table 1.

As shown in Examples 1 to 10 in Table 1 above, any composition in which the blending amount of the polymerizable monomer is within the range specified in the present invention can be cured under the light irradiation conditions of this time, and the surface The hardness showed a value of 8HV or more. The color of the resulting cured product is pale yellow, and the value of the coloration degree ΔE ^* at the time of curing has a C class tolerance (6.5 to 13.0) or a D class tolerance (13.0 to 25.0 ). That is, it can be said that the color tone of the composition did not change significantly during curing. On the other hand, when the specific cationically polymerizable monomer was not contained, although the photocurability was good, the cured product was relatively strongly colored, and the value of the coloration degree ΔE ^* at the time of curing did not exceed the D class tolerance. , and a relatively large change in color tone was confirmed during curing. (Comparative Examples 1 to 4). In Comparative Example 3, although 5 parts by mass of EP-2B, which is a cationic polymerizable monomer having a carbonyl group, was contained, the coloring was large as described above. This is probably because the epoxy group and carbonyl group of EP-2B are separated from each other, and stable cationic species are not generated due to the participation of neighboring groups. Moreover, when the content of the specific cationically polymerizable monomer exceeds the range specified in the present invention, the photocurability is low, and a cured product could not be obtained under the photoirradiation conditions of this time. (Comparative Examples 5 and 6)

Claims (6)

(a) a cationically polymerizable monomer and (b) a photocationically curable composition containing a photocationic initiator,
The (a) cationically polymerizable monomer has the following formula

(In the above formula, * represents a point of attachment to the rest of the molecule, X represents a divalent group having 1 to 3 atoms in the main chain, Y represents a bond or a methylene group, R ¹ represents a hydrogen atom or a hydrocarbyl group having 1 to 12 carbon atoms.)
Consists of a specific cationically polymerizable monomer consisting of a compound containing a partial structure represented by and a non-specific cationically polymerizable monomer other than the specific cationically polymerizable monomer,
The content of the specific cationically polymerizable monomer based on the total weight of the (a) cationically polymerizable monomer is 1 to 25% by mass,
The photo cationic curable composition characterized by: 2. The photocationically curable composition according to claim 1, wherein the (b) photocationic initiator comprises a photoacid generator, a photosensitizer and/or an electron-donating compound. Photocationic curing according to claim 2, wherein the photoacid generator is an iodonium salt compound, the photosensitizer is an α-diketone compound, and the electron donating compound is a polycyclic aromatic compound and/or a thiophene compound. sex composition. 4. The photocationically curable composition according to any one of claims 1 to 3, wherein said non-specific cationically polymerizable monomer comprises an epoxy compound and/or an oxetane compound. A dental curable composition comprising the photo-cationically curable composition according to any one of claims 1 to 4. 6. A dental hardenable composition according to claim 5, further comprising a filler.