CURABLE COMPOSITION

Abstract: A curable composition comprising (A) a monofunctional monomer containing a (meth)acrylate group; (B) a polyfunctional monomer containing a (meth)acrylate group; (C) a acidic group and a (meth)acrylate group containing compound having at least one (meth)acryloyloxyl group; and (D) a trialkylboron or an oxide thereof.

Description: The present invention relates to a curable composition effective for an adhesive for dental use which is superior in the water-resistant bonding and in the low temperature curing performance at around ordinary temperatures and which exhibits a superior bonding performance for natural materials of teeth, such as, enamel and dentine, as well as for dental alloys, without imparting to the dental pulp any defective influence, such as irritation. Hitherto, there have been proposed many adhesive compositions for orthodontic and corrective treatments of human teeth, composed of a monomer polymerizable by radical polymerization, such as, a vinyl monomer based on (meth)acrylate and so on, and of a catalyst. For example, a curable composition composed of a vinyl monomer based on (meth)acrylate, an aromatic carboxylic acid (anhydride) containing (meth)acryloyloxy group, an amine and a sulfinic acid (salt), as disclosed in JP-A-44508/1985; an adhesive composition consisting of an ester of (meth)acrylic acid existing at ordinary temperatures as a liquid, an amine, a sulfinic acid (salt) and a peroxide, as decribed in JP-A-39331/1978; and an adhesive composition consisting of MMA, 4-META and tributyl borane, as reported in the magazine "The Japanese Journal of Conservative Dentistry" 28 , 452-478, (1985) may be of typical. However, it has been very difficult to attain sufficient adhesion onto the natural human teeth, especially onto the dentine treated with a mild etching agent, such as EDTA, using the curable compositions and adhesives of prior art. According to the present invention there is provided a curable composition comprising (A) a (meth)acrylate) monomer containing only one (meth)acryloyloxy group (for convenience referred to herein as a monofunctional (meth)acrylate); (B) a (meth)acrylate monomer containing two or more (meth)acryloyloxy groups (for convenience referred to herein as a polyfunctional (meth)acrylate); (C) a (meth)acrylate compound which is at least one of: (C₁) an aromatic polycarboxylic acid or anhydride thereof having at least one (meth)acryloyloxy group; and (C₂) a partial ester of a phosphoric acid or ester of a sulfonic acid, each having at least one (meth)acryloyloxy group; (D) a trialkylboron wherein each alkyl group contains 2 to 5 carbon atoms or an oxide thereof, the composition comprising from 5 to 95 weight percent (A) and 95 to 5 weight percent (B), each being based on the total weight of (A) + (B), 1 to 50 parts by weight of (C) per 100 parts by weight of (A) + (B), and 2 to 100 parts by weight of (D) per 100 parts by weight of (A) + (B) + (C). The curable composition of the invention has excellent low temperature curability at ordinary temperatures and excellent water-resistant bonding. It exhibits good adhesion to enamel, dentine and various dental alloys. Accordingly it can be used as a dental adhesive in the corrective treatment of human teeth without imparting to the dental pulp any defective influence, such as irritation. The monofunctional (meth)acrylate (A) may contain functional groups other than the (meth)acryloyloxy group. As the monofunctional (meth)acrylate (A), there may be enumerated: (A₁) hydrocarbyl group-containing (meth)acrylates, such as, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, dodecyl (meth)acrylate, lauryl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate and isobornyl (meth)acrylate; (A₂) hydroxyl group-containing (meth)acrylates, such as 2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate; (A₃) ethylene glycol unit-containing (meth)acrylates, such as ethylene glycol monomethyl ether (meth)acrylate, ethylene glycol monoethyl ether (meth)acrylate, ethylene glycol monododecyl ether (meth)acrylate, diethylene glycol monomethyl ether (meth)acrylate, polyethylene glycol monomethyl ether (meth)acrylate and polyethylene glycol monoethyl ether (meth)acrylate; (A₄) fluoro substituent group-containing (meth)acrylates, such as trifluoroethyl(meth)acrylate and perfluorooctyl(meth)acrylate; (A₅) silane (meth)acrylates, such as γ-(meth)acryloyloxypropyl trimethoxy silane and γ-(meth)acryloyloxypropyl tri(trimethylsiloxy) silane; and (A₆) tetrahydofurfuryl (meth)acrylate, wherein they may be employed solely or as mixtures of two or more of them. Among them, alkyl (meth)acrylates, such as methyl (meth)acrylate, ethyl (meth)acrylate, hexyl (meth)acrylate and dodecyl (meth)acrylate as well as hydroxyl group-containing (meth)acrylates, such as 2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate are preferable and, especially, methyl methacrylate, n-hexyl methacrylate, 2-hydroxyethyl methacrylate and 2-hydroxypropyl methacrylate are most preferable to use either solely or as mixtures of them; Examples of the polyfunctional (meth)acrylate (B) include: (B₁) poly(meth)acrylates of alkane polyols, such as ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, hexylene glycol di-(meth)acrylate, trimethylolpropane tri(meth)acrylate, glycerol tri(meth)acrylate and pentaerythritol tetra(meth)acrylate; (B₂) poly(meth)acrylates of (poly)oxyalkanepolyols, such as diethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, dibutylene glycol di(meth)acrylate and dipentaerythritol hexa(meth)acrylate; (B₃) epoxy(meth)acrylates, represented by the general formula (I) in which R¹ and R² represent each H or CH₃, n is zero or a positive integer and R³ denotes a divalent aliphatic, cycloaliphatic or aromatic residue which may contain an oxygen or sulfur atom; (B₄) cycloaliphatic or aromatic di(meth)acrylates represented by the general formula (II) in which R¹ and R² stand each for H or CH₃ and R³ denotes a divalent cycloaliphatic or aromatic residue having at least one cyclic group and which may contain an oxygen or sulfur atom; and (B₅) cycloaliphatic di(meth)acrylates expressed by the general formula (III) in which R¹ and R² stand each for H or CH₃ and R³ denotes a divalent cycloaliphatic residue having at least one cyclic group and which may contain an oxygen or sulfur atom. Examples of aliphatic, cycloaliphatic and aromatic residue of R³ in the above general formula (I) include: Examples of cycloaliphatic and aromatic residues of R³ in the above general formula (II) include: Examples of cycloaliphatic residue of R³ in the above general formula (III) include: Among the polyfunctional (meth)acrylates, poly(meth)acrylates of alkanepolyols, poly(meth)acrylates of (poly)oxyalkanepolyols and epoxy (meth)acrylates may preferably be employed and, in particular, ethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, and compounds represented by the formula in which R¹ and R² stand each for H or CH₃, are preferable for use. Examples of polyfunctional (meth)acrylate (B) may further include: (B₆) polyfunctional (meth)acrylates represented by the general formula (IV) in which R¹ and R² stand each for H or CH₃, R³ denotes a divalent aromatic residue having at leat one aromatic ring and which may contain an oxygen or sulfur atom and n and m represent each a positive integer. As the divalent aromatic residue of R³ of the above general formula (IV), there may be exemplified: Among them, are more preferable for the residue of R³ and, in particular, are most preferable. For the polyfunctional (meth)acrylate (B₆) of the general formula (IV), there may be enumerated: in which R¹ and R² stand each for H or CH₃ and m+n = 2 - 20; in which R¹ and R² stand each for H or CH₃ and m+n = 2 - 20; in which R¹ and R² stand each for H or CH₃ and m+n = 2 - 20; in which R¹ and R² stand each for H or CH₃ and m+n = 2 - 20; in which R¹ and R² stand each for H or CH₃ and m+n = 2 - 20; and in which R¹ and R² stand each for H or CH₃ and m+n = 2 - 20; and in particular, in which m+n = 2 - 10 and in which m+n = 2 - 10 are most preferable. As the polyfunctional (meth)acrylate (B), (B₇) polyfunctional (meth)acrylates having in the molecule at least one urethane linkage may also be employed, for example, adducts of one mole of a diisocyanate compound with two moles of a hydroxyl group-containing (metyh)acrylate, such as 2-hydroxyethyl (meth)acrylate. Here, as the diisocyanate compound, aliphatic, cycloaliphatic and aromatic diisocyanate compounds can be employed, such as hexamethylene diisocyanate, lysine diisocyanate, 2,2(4),4-trimethylhexamethylene diisocyanate, dicyclohexyldimethylmethane-p,p'-diisocyanate, isophorone diisocyanate, tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate and naphthalene diisocyanate. As examples of polyfunctional (meth)acrylates (B₇) there may be enumerated: in which R¹ and R² stand each for H or CH₃; in which R¹ and R² stand each for H or CH₃; in which R¹, R², R³ and R² stand each for H or CH₃; in which R¹ and R² stand each for H or CH₃; in which R¹ and R² stand each for H or CH₃; in which R¹ and R² stand each for H or CH₃; in which R¹ and R² stand each for H or CH₃; in which R¹ and R² stand each for H or CH₃; and in which R¹ and R² stand each for H or CH₃. Among these polyfunctional (meth)acrylates (B₇) the aliphatic and cycloaliphatic ones are preferred and, and are most preferable. The polyfunctional (meth)acrylates (B) can be used singly or as mixtures of two or more of them. Concrete examples for the aromatic polycarboxylic acid or anhydride thereof (C₁) include those which have a molecular structure, in which at least one hydroxyl group of an alkane polyol having at least two hydroxyl groups and which may contain an oxygen atom is esterified with (meth)acrylic acid and at least one other hydroxyl group thereof is esterified with one carboxyl group of an aromatic polycarboxylic acid having at least three carboxyl groups. An aromatic polycarboxylic acid having at least three carboxyl groups in which at least two carboxyl groups are combined to neighboring carbon atoms in the aromatic nucleus is preferable, for example, hemimellitic acid, trimellitic acid, prehnitic acid, mellophanic acid or pyromellitic acid. Examples of (C₁) include 4-(meth)acryloyloxymethoxycarbonyl phthalic acid and its anhydride, 4-(meth)acryloyloxyethoxycarbonyl phthalic acid and its anhydride, 4-(meth)acryloyloxybutoxycarbonyl phthalic acid and its anhydride, compounds represented by the formulae in which n is an integer of 6 - 12 and R stands for H or CH₃, in which n is an integer of 2 - 50 and R stands for H or CH₃, and in which n is an integer of 1 - 50 and R stands for H or CH₃; and further 4-[2-hydroxy-3-(meth)acryloyloxypropoxycarbonyl] phthalic acid and its anhydride, 2,3-bis(3,4-dicarboxybenzoyloxy)propyl (meth)acrylate and its anhydride, 2-(3,4-dicarboxybenzoyloxy)-1,3-dimethacryloyloxy propane and anhydride thereof. Concrete examples of a compound (C₂) which is a partial ester of phosphoric acid, namely a mono- or diester of phosphoric and mixture of them, or a sulfonate, namely an ester of sulfonic acid, each having in the molecule at least one (meth)acryloyloxyl group include 2-(meth)acryloyloxyethylphenyl acid phosphate, bis-[2-(meth)acryloyloxyethyl] acid phosphate, bis-[3-(meth)acryloyloxypropyl] acid phosphate, 2-(meth)acryloyloxyethyl-phenylphosphonate, compounds represented by the formulae The acid group-containing monomers (C₁) based on (meth)acrylate and each having in the molecule at least one (meth)acryloyloxyl group also can be employed solely or in mixture of two or more of them. Among them, aromatic polycarboxylic acids and their anhydrides (C₁) having in the molecule at least one acryloyloxy group are preferred and, in particular, 4-(meth)acryloyloxyethoxycarbonyl phthalic acid and its anhydride are most preferable. Particularly, the use of 4-methacryloyloxyethoxycarbonyl phthalic acid anhydride improves the adhesion onto teeth and the durability in aqueous media. Concrete examples of the trialkylboron or oxide thereof (D) to be employed in the curable composition according to the present invention include triethylboron, tripropylboron, triisopropylboron, tri-n-butylboron, tri-n-amylboron, triisoamylboron and tri-sec-amylboron and oxides of these trialkylborons, in which these compounds are partly oxidized. The trialkylboron or oxide thereof (D) can also be employed solely or in a mixture of two or more of them. Among these, tri- n-butylboron and its oxide are preferable. Preferred formulations contain 10 - 95 % by weight of monofunctional (meth)acrylate (A) and 90 - 5 % by weight of polyfunctional (meth)acrylate (B) and, most preferably, 25 - 90 % by weight of (A) and 75 - 10 % by weight of (B), based on the total weight of (A) + (B). Within the ranges given above, a curable composition according to the present invention will exhibit good adhesion to dentine and excellent durability in aqueous media and, in particular, high bonding strength and high water-fastness will be attained even when etching dentine with a mild acid, such as EDTA. The amount of the acidic group-containing monomer (C) in the curable composition according to the present invention is from 1 to 50 parts by weight, preferably from 3 to 30 parts by weight, especially from 5 to 15 parts by weight, based on 100 parts by weight of (A) + (B). The amount of trialkylboron or oxide (D) in the curable composition according to the present invention is from 2 to 100 parts by weight, preferably from 5 to 70 parts by weight and, most preferably, from 5 to 50 parts by weight, based on 100 parts by weight of (A) + (B) + (C). For the practical use of the conposition according to the present invention, the trialkylboron or oxide (D) is mixed with a premix of the monomers (A), (B) and (C) of the composition from a separately reserved stock directly before the practical application, since the polymerization reaction will start within a period of from several seconds to several tens minutes after the mixing with the premix. The curable composition according to the present invention may include beside the above described essential components other additives, for example, powdery inorganic filler, organic polymer substances and polymerization retarders. Examples of powdery inorganic filler are kaolin, talc, clay, calcium carbonate, silica powder, powdered silica-alumina, pulverous alumina, titanium oxide, calcium phosphate, pulverized glass and quartz powder. Examples of organic polymer substance include waxes, copolymer of ethylene/vinyl acetate, polymethyl acrylate, polymethyl methacrylate and copolymers of these. These additives may be incorporated in an adequate amount. The curable composition according to the present invention exhibits superior low temperature curing and excellent water-resistant bonding performance together with superior adhesion onto teeth materials, such as enamel and dentine without causing any irritation to the dental pulp, so that it can be used for various applications, such as, for bonding agent, for composite resins and hard resins for dental uses and as composite resinous mass for accuracy work in various fields other than dental uses. An application for bonding agent for the composite resin in dental use may be most preferable. In the following, the present invention will further be described concretely by way of Examples. Also Application Examples of the composition for preparation of light-curable dental composite resin and dental filling mass are given. In the Examples and Comparison Examples, compounds used are denoted by each specific abbreviation as recited below: MMA : Methyl methacrylate HMA : n-Hexyl methacrylate HEMA : 2-Hydroxyethyl methacrylate HPMA : 2-Hydroxypropyl methacrylate NPG : Neopentyl glycol dimethacrylate 2G : Diethylene glycol dimethacrylate PMMA : Polymethyl methacrylate BIS-GMA: DPEMA : 2,6E : in which m+n = 2.6 (average), RDMA : UDMA : GUMM : HEIP : 4-META: 4-MET : TBB·O : A partial oxidation product of tri-n-butylboron BPO : Benzoyl peroxide DEPT : Diethanol-p-toluidine PTSNa : Sodium paratoluenesulfinate HQME : Hydroquinone monomethyl ether For evaluating the bonding strength of the compositions tested, the following procedures were employed: A front tooth of a cattle was polished on its enamel face or its dentine face with a #600 emery paper to smooth the surface. The tooth was then subjected to an etching treatment with 65 % by weight aqueous solution of phosphoric acid for 30 seconds for the enamel and with 0.3 M aqueous EDTA·2Na - 0.2 M aqueous EDTA·Fe·Na (pH 7.4) for 60 seconds for the dentine. After a sufficient water wash, the etched surface was dried by blowing air. Then a sheet of cellophane tape (about 13 mm x 13 mm) having a circular cut off of a diameter of 5 mm was sticked thereon. A bonding agent for use for each Example or Comparison Example was coated on the exposed tooth surface in the cut off of the tape and the coated layer was blown briefly with air. On the other hand, a cylindrical Teflon (trademark) mold having a mold recess with a diameter of 5 mm and a depth of 2 mm as corresponding to the cut off circle of the tape was charged with a light-curable dental composite resin as explained afterwards and the so charged layer was covered by a cellophane paper. The resin layer was then irradiated through the cellophane paper by a visible light using a visible light projector Translux (trademark of the firm Kulzer) for 30 seconds to harden the composite resin. Then, an acryl resin rod was bonded onto the so hardened surface of the composite resin with an adhesive Super-Bond C&B (trademark, a product of the firm Sun Medical) to prepare a test piece for testing bonding strength. After storage for 30 minutes at room temperature, the test piece was immersed in water at 37°C for 24 hours and then taken out and kept in air at 23°C for 10 minutes, before it was subjected to a tensile test at 23 °C at a rate of 2 mm/min. The rupture face of the test piece after the tensile test was found as consisting of either the material of the sample tooth, material of composite resin resulting from an aggregation rupture or interface between the composite resin layer and dentine layer. Preparation Example I Preparation of a Light-Curable Composite Resin In a two-roll kneader, 7.5 g of triethylene glycol dimethacrylate, 7.5 g of 1,3-bis-(methacryloxyethoxy)-benzene, 15 g of an adduct of one mole of 2,2,4-trimethyl hexamethylenediamine diisocyanate with 2 moles of 2-hydroxyethyl methacrylate, 40 g of composite filler powder synthesized by the method explained afterwards, 30 g of Micropowder Silica RM-50 (fine powder silica product of the firm Nippon Aerosil K.K.) and 4 mg of hydroquinone monomethyl ether were kneaded to prepare a mixture. 10 g of this mixture were mixed with 45 mg of camphorquinone and 45 mg of 4-diethylaminobezoic acid using a spatula sufficiently to prepare a light-curable composition. Preparation Example II Preparation of Composite Filler Powder 0.1 g of benzoyl peroxide was dissolved in 10 g of trimethacrylate of trimethylolpropane and the solution was placed in an agate mortar and thereto was admixed fine pulverous silica Aerosil R972 (trademark of Nippon Aerosil K.K., average particle size of 16 mµ) in small portions. The consistency increased gradually until a state of a sticky aggregated powdery mass is obtained. The resulting mixture was transferred in a small rubber roll kneader and thereto was further added powdery silica in portions in an amount of total of 9.5 g. The so obtained paste was taken out of the roll kneader and was molded on a press at a temperature of 120 °C under a pressure of 150 - 200 Kg/cm² for 10 minutes to effect heat curing thereof. The hardened product was crushed in a ball mill and was then sieved. 18.0 g of composite filler powder of an undersize of 230-mesh were obtained. The average particle size of this powder was 11 µm. Example 1 6 g of MMA, 3 g of NPG, 1 g of 4-META, namely 4-methacryloxyethoxycarbonyl phthalic anhydride, and 2 mg of HQME were mixed together at room temperature to prepare a liquid monomer mixture (A). To 2 parts by weight of this liquid mixture, there was admixed 1 part by weight of TBB·O (a partial oxidation product of tri-n-butylboron marketed from the firm Sun Medical) to prepare a curable composition. This mixture was coated on a test sample of cattle tooth using a painting brush in a thin coating layer, whereupon a test piece for testing the bonding strength as described above was prepared by the procedures described previously. The results are summarized in Table 1. Examples 2 - 8, Comparison Example 1 and Comparison Examples 3 - 4 A liquid monomer mixture (A) was prepared as in Example 1 using the monomer components in amounts as given in Table 1. By mixing the liquid mixture (A) with TBB·O (product of Sun Medical) in the proportion given in Table 1, each curable test composition was prepared. Using this curable composition, the test piece for testing the bonding strength was prepared in the manner as given in Example 1. Results are summarized also in Table 1. Comparison Example 2 Using 100 parts by weight of MMA, 11 parts by weight of 4-META, 80 parts by weight of PMMA (for Super-Bond C&B of Sun Medical) and 2 mg of hydroquinone monomethyl ether, a liquid monomer mixture (A) was prepared. By mixing this liquid mixture (A) with TBB·O in a proportion as given in Table 1, a curable composition was prepared. The preparation of test piece was effected in the manner as given in Comparison Example 1. Results are summarized also in Table 1. Comparison Example 5 6 g of MMA, 3 g of NPG, 1 g of 4-META, 0.2 g of BPO and 2 mg of HQME were mixed at room temperature to prepare a liquid monomer mixture (A). On the other hand, another liquid mixture was prepared from 0.1 g of DEPT, 0.4 g of PTSNa and 9.5 g of 99 % ethanol. By mixing the above liquid mixtures (A) and (B) in equal amount, a cuarable composition was obtained. This composition was coated on the sample tooth using a painting brush. The preparation of test piece for testing the bonding strength was effected in the manner as given in Example 1. Results are summarized also in Table 1. Example 9 8 g of MMA, 1 g of RDMA, namely 1,3-bis-(methacryloxyethoxy) benzene, 1 g of 4-META, 0.1 g of PMMA and 2 mg of HQME were mixed at room temperature to prepare a liquid monomer mixture (A). To 2 parts by weight of this liquid mixture, there was admixed 1 part by weight of TBB·O to prepare a curable composition. This mixture was coated on the test sample of cattle tooth using a painting brush, whereupon a test piece for testing the bonding strength as described previously was prepared by the procedures set forth previously. The results are summarized in Table 2. Examples 10 - 12 and Comparison Examples 6 - 7 A test piece for testing the bonding strength was prepared in the manner as given in Example 9, except that monomer compositions given in Table 2 were used instead of using those of Example 9. Results are summarized also in Table 2. Example 13 - 16 and Comparison Example 8 A liquid monomer mixture (A) was prepared as in Example 9 using the monomer components of Table 2 in amounts as given therein. By mixing the liquid mixture (A) with TBB·O in the proportion given in Table 2, each curable test composition was prepared. Using this curable composition, the test piece for testing bonding strength was prepared in the manner as given in Example 9. Results are summarized also in Table 2. Comparison Example 9 2.7 g of HEMA, 6.3 g of 2,6E, 1 g of 4-META, 0.1 g of BPO and 2 mg of HQME were mixed at room temperature to prepare a liquid monomer mixture (A). On the other hand, a liquid mixture (B) was prepared from 0.05 g of DEPT, 0.2 g of PTSNa and 9.75 g of 99 % ethanol. By mixing the above liquid mixtures (A) and (B) in equal amount, a cuarable composition was obtained. This composition was coated on the sample tooth using a painting brush. The preparation of test piece for testing the bonding strength was effected in the manner as explained previously. Results are summarized also in Table 2. Example 17 8 g of MMA, 1 g of UDMA, 1 g of 4-META, 0.1 g of PMMA and 2 mg of HQME were mixed at room temperature to prepare a liquid monomer mixture (A). To 2 parts by weight of this liquid mixture, there was admixed 1 part by weight of TBB·O to prepare a curable composition. This mixture was coated on the test sample of cattle tooth using a painting brush, whereupon a test piece for testing the bonding strength as described previously was prepared by the procedures set forth previously. The results are summarized in Table 3. Examples 18 - 20 and Comparison Example 10 A test piece for testing bonding strength was prepared in the manner as given in Example 17, except that monomer compositions given in Table 3 were used instead of using those of Example 17. Results are summarized also in Table 3. Examples 21 - 24 and Comparison Example 11 A liquid monomer mixture (A) was prepared as in Example 17 using the monomer components of Table 3 in amounts as given therein. By mixing the liquid mixture (A) with TBB·O in the proportion given in Table 3, each curable test composition was prepared. Using this composition, the test piece for testing the bonding strength was prepared. Results are summarized also in Table 3. Comparison Example 12 2.7 g of HEMA, 6.3 g of HEIP, 1 g of 4-META, 0.1 g of BPO and 2 mg of HQME were mixed at room temperature to prepare a liquid monomer mixture (A). On the other hand, a liquid mixture (B) was prepared from 0.05 g of DEPT, 0.2 g of PTSNa and 9.75 g of 99 % ethanol. By mixing the above liquid mixtures (A) and (B) in equal amount, a cuarable composition was obtained. This composition was coated on the sample tooth using a painting brush and the coating layer was then blown by air briefly to evaporate off ethanol. The preparation of test piece for testing the bonding strength was effected in the manner as explained previously. Results are summarized also in Table 3.

Claims: A curable composition comprising (A) a (meth)acrylate monomer containing only one (meth)acryloyloxy group; (B) a (meth)acrylate) monomer containing two or more (meth)acryloyloxy groups; (C) a (meth)acrylate which is at least one of: (C₁) an aromatic polycarboxylic acid or anhydride thereof having at least one (meth)acryloyloxy group; and (C₂) a partial ester of a phosphoric acid or ester of a sulfonic acid, each having at least one (meth)acryloyloxy group; (D) a trialkylboron wherein each alkyl group contains 2 to 5 carbon atoms or an oxide thereof, the composition comprising from 5 to 95 weight percent (A) and 95 to 5 weight percent (B), each being based on the total weight of (A) + (B), 1 to 50 parts by weight of (C) per 100 parts by weight of (A) + (B), and 2 to 100 parts by weight of (D) per 100 parts by weight of (A) + (B) + (C). A curable composition according to claim 1 wherein (A) is at least one of: (A₁) a (meth)acrylate containing a hydrocarbyl group of up to 12 carbon atoms; (A₂) a hydroxyl group-containing (meth)acrylate; (A₃) an ethylene glycol unit-containing (meth)acrylate; (A₄) a fluoro substituent group-containing (meth)acrylate; (A₅) a silane (meth)acrylate; and (A₆) tetrahydrofurfuryl (meth)acrylate. A curable composition according to claim 1 or 2 wherein (B) is at least one of: (B₁) a poly(meth)acrylate of an alkane polyol; (B₂) a poly(meth)acrylate of a (poly)oxyalkanepolyol; (B₃) an epoxy(meth)acrylate of formula (I): in which R¹ and R² each independently is H or CH₃, n is zero or a positive integer, and R³ is a divalent aliphatic, cycloaliphatic or aromatic residue of 2 to 15 carbon atoms which may or may not contain an oxygen or sulfur atom; (B₄) a cycloaliphatic or aromatic (di(meth)acrylate of formula (II): in which: R¹ and R² each independently is H or CH₃; and R³ is a divalent cycloaliphatic or aromatic residue of 6 to 15 carbon atoms which may or may not contain therein a oxygen or sulfur atom; (B₅) a cycloaliphatic di(meth)acrylate of formula (III): in which: R¹ and R² each independently is H or CH₃; and R³ is a divalent cycloaliphatic residue of 6 to 15 carbon atoms which may or may not contain an oxygen or sulfur atom; (B₆) a compound of formula (IV): in which R¹ and R² each independently is H or CH₃; R³ is a divalent aromatic residue of 6 to 15 carbon atoms which may or may not contain therein an oxygen or sulfur atom; and n and m each independently is a positive integer with n + m = 2 to 20; and (B₇) a polyfunctional monomer based on a (meth)acrylate having at least one urethane linkage. A curable composition according to claim 1, 2 or 3 wherein (D) is at least one of triethylboron, tri-n-propylboron, triisopropylboron, tri-n-butyl-boron, tri-n-amylboron, triisoamylboron, tri-sec-amylboron and oxidation product thereof. Use of a curable composition as claimed in any one of the preceding claims for preparing a dental adhesive. Articles obtained by shaping and curing a composition as claimed in any one of claims 1 to 4.

Inventors: ARATA, MASAMI, SAKASHITA, TAKESHI, YAMAMOTO, TAKASHI
Applicants: MITSUI PETROCHEMICAL INDUSTRIES, LTD.
Application year: 1987
Main classification: A61K6
IPC codes: C08F220, A61K6