Photopolymerization initiator, photocurable composition, and dental material

Abstract

This photopolymerization initiator comprises: an ionic boron compound including a boron-containing anion and a counter-cation for the boron-containing anion; and a photosensitizer (1) that is at least one compound selected from the group consisting of 1,2-diketone compounds and compounds represented by formula (A). In formula (A), R1A and R2A are each independently an optionally substituted aromatic hydrocarbon group.

Description

Photopolymerization initiator, photocurable composition, and dental material

[0001] The present disclosure relates to photopolymerization initiators, photocurable compositions, and dental materials.

[0002] Photopolymerization initiators have been used in various fields in recent years. For example, in the dental field, photopolymerization initiators are often used for the polymerization of dental curable compositions such as composite resins for repairing dental defects. Photopolymerization initiators in the dental field often contain photoradical generators such as camphorquinone (hereinafter also referred to as "CQ"), photobase generators, etc. In particular, the combination of "CQ" and a tertiary amine is one of the commonly used forms of dental photopolymerization initiators.

[0003] For example, Patent Document 1 discloses a combination of an α / diketone such as camphorquinone (CQ) and an aromatic hydrocarbon amine compound such as ethyl N,N-dimethylaminobenzoate as an example of a photopolymerization initiator used in dental restorative compositions such as the above-mentioned dental composite resin (hardenable composition).

[0004] Patent Document 1: Japanese Patent Application Laid-Open No. 2016-8211

[0005] There are cases where a photocurable composition is required to have excellent polymerization depth (i.e., excellent polymerization properties (i.e., curing properties) from the surface layer including the light-irradiated surface to the deep portion). For example, when a photocurable composition as a dental composite resin is used to fill a deep defect in a tooth, the photocurable composition may be required to have excellent polymerization depth in order to sufficiently photocure the composition from the surface layer including the light-irradiated surface to the deep portion.

[0006] On the other hand, there are cases where it is required to substantially not use an aromatic hydrocarbon amine compound (for example, the aromatic hydrocarbon amine compound described in Patent Document 1) as a component of a photopolymerization initiator, or to reduce the amount used.

[0007] Therefore, an object of one embodiment of the present disclosure is to provide a photopolymerization initiator that can improve the polymerization depth of a photocurable composition even when an aromatic hydrocarbon amine compound is not substantially used or the amount used is reduced as a component of the photopolymerization initiator; a photocurable composition containing this photopolymerization initiator; and a dental material that contains at least one of the photocurable composition and a cured product thereof.

[0008] Specific means for solving the above problems include the following aspects: <1> A photopolymerization initiator comprising: an ionic boron compound containing a boron-containing anion and a counter cation for the boron-containing anion; and a photosensitizer (1) which is at least one selected from the group consisting of 1,2-diketone compounds and compounds represented by the following formula (A):

[0009]

[0010] In formula (A), R １Ａ and R ２Ａ are each independently an aromatic hydrocarbon group which may have a substituent.

[0011] <2> The photopolymerization initiator according to <1>, wherein the boron-containing anion is an anion represented by the following formula (B):

[0012]

[0013] In formula (B), R １Ｂ , R ２Ｂ , R ３Ｂ , and R ４Ｂ are each independently a monovalent organic group.

[0014] <3> R １Ｂ , R ２Ｂ , R ３Ｂ , and R ４Ｂ <4> The photopolymerization initiator according to any one of <1> to <3>, wherein the counter cation is a quaternary ammonium cation. <5> The photopolymerization initiator according to any one of <1> to <4>, wherein the 1,2-diketone compound is camphorquinone. <6> The photopolymerization initiator according to <1> to <4>, wherein the R in formula (A) is an alkyl group. １Ａ and the R２Ａ are each independently a phenyl group having at least one substituent containing a heteroatom. <7> The photopolymerization initiator according to any one of <1> to <6>, wherein the content of the photosensitizer (1) relative to the total content of the ionic boron compound and the photosensitizer (1) is 5% by mass to 40% by mass. <8> A photocurable composition containing the photopolymerization initiator according to any one of <1> to <7> and a monomer. <9> The photocurable composition according to <8>, further containing a filler. <10> The photocurable composition according to <8> or <9>, which does not contain an aromatic hydrocarbon amine compound, or, if it contains one, the content of the aromatic hydrocarbon amine compound relative to the total amount of the photocurable composition is less than 0.01% by mass. <11> The photocurable composition according to any one of <8> to <10>, which is a photocurable composition for dental use. <12> A dental material comprising at least one of the photocurable composition according to any one of <8> to <11> and a cured product of the photocurable composition.

[0015] According to one embodiment of the present disclosure, there are provided a photopolymerization initiator that can improve the polymerization depth of a photocurable composition even when an aromatic hydrocarbon amine compound is not substantially used or the amount used is reduced as a component of the photopolymerization initiator; a photocurable composition containing this photopolymerization initiator; and a dental material that contains at least one of the photocurable composition and a cured product thereof.

[0016] In the present disclosure, a numerical range indicated using "to" means a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in stages in the present disclosure, the upper or lower limit value described in a certain numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in the numerical ranges described in the present disclosure, the upper or lower limit value described in a certain numerical range may be replaced with a value shown in the Examples. In the present disclosure, a combination of two or more preferred embodiments is a more preferred embodiment. In the present disclosure, when multiple substances corresponding to each component are present, the amount of each component refers to the total amount of multiple substances unless otherwise specified. In the present disclosure, "(meth)acrylic" means acrylic and methacrylic, and "(meth)acryloyl" means acryloyl and methacryloyl.

[0017] [Photopolymerization Initiator] The photopolymerization initiator of the present disclosure comprises: an ionic boron compound containing a boron-containing anion and a counter cation for the boron-containing anion; and a photosensitizer (1) that is at least one selected from the group consisting of 1,2-diketone compounds and compounds represented by formula (A) described below. When contained as a component of a photocurable composition, the photopolymerization initiator of the present disclosure can improve the polymerization depth of the photocurable composition. This effect can be achieved even when an aromatic hydrocarbon amine compound is substantially not used as a component of the photopolymerization initiator, or when the amount used is reduced. This is thought to be because the ionic boron compound in the photopolymerization initiator of the present disclosure has a function similar to that of the aromatic hydrocarbon amine compound in conventional photopolymerization initiators (e.g., the photopolymerization initiator described in Patent Document 1, which is a combination of an α-diketone and an aromatic hydrocarbon amine compound).

[0018] <Ionic boron compound> The photopolymerization initiator of the present disclosure includes at least one ionic boron compound. The ionic boron compound includes a boron-containing anion and a counter cation for the boron-containing anion.

[0019] (Boron-containing anion) The ionic boron compound contains a boron-containing anion. The boron-containing anion is not particularly limited as long as it is an anion containing boron. The boron-containing anion is preferably an anion represented by the following formula (B):

[0020]

[0021] In formula (B), R １Ｂ , R ２Ｂ , R ３Ｂ , and R ４Ｂ are each independently a monovalent organic group.

[0022] In formula (B), R １Ｂ ~R ４Ｂ The monovalent organic group represented by the formula (I) is preferably a hydrocarbon group, more preferably an alkyl group or an aromatic hydrocarbon group.

[0023] R １Ｂ ~R ４Ｂ The number of carbon atoms in the hydrocarbon group as the monovalent organic group represented by the formula (I) is preferably 1 to 20, more preferably 1 to 12, even more preferably 1 to 10, and still more preferably 2 to 8.

[0024] R １Ｂ ~R ４Ｂ The number of carbon atoms in the alkyl group as a monovalent organic group represented by the formula (I) is preferably 1 to 20, more preferably 1 to 12, even more preferably 1 to 10, and still more preferably 2 to 8.

[0025] R １Ｂ ~R ４Ｂ The number of carbon atoms in the aromatic hydrocarbon group as the monovalent organic group represented by the formula (I) is preferably 6 to 20, more preferably 6 to 16, and even more preferably 6 to 12. The aromatic hydrocarbon group is preferably a phenyl group or a naphthyl group.

[0026] R １Ｂ , R ２Ｂ , R ３Ｂ , and R ４Ｂ It is preferable that at least one of R is an alkyl group. More preferably, R １Ｂ , R ２Ｂ , R ３Ｂ, and R ４Ｂ one of which is an alkyl group, and R １Ｂ , R ２Ｂ , R ３Ｂ , and R ４Ｂ The remainder of the above are each independently an alkyl group or an aromatic hydrocarbon group.

[0027] Specific examples of boron-containing anions are shown below, but the boron-containing anions are not limited to these examples. In the specific examples, "n-" means normal, and "n-C ４ H ９ " means a normal butyl group.

[0028]

[0029] (Counter Cation) The ionic boron compound contains a counter cation for the boron-containing anion. Examples of the counter cation include an alkyl metal ion, an alkaline earth metal ion, a quaternary ammonium cation, and a quaternary phosphonium cation. The counter cation is preferably a sodium ion, a lithium ion, a potassium ion, a magnesium ion, a calcium ion, a strontium ion, a quaternary ammonium ion, or a quaternary phosphonium cation, more preferably a quaternary ammonium cation, and even more preferably a quaternary ammonium cation represented by the following formula (X):

[0030]

[0031] In formula (X), R １Ｘ , R ２Ｘ , R ３Ｘ , and R ４Ｘ are each independently a monovalent organic group.

[0032] In formula (X), R １Ｘ ~R ４Ｘ The monovalent organic group represented by the formula (I) is preferably a hydrocarbon group, more preferably an alkyl group or an aromatic hydrocarbon group.

[0033] R １Ｘ ~R ４ＸThe number of carbon atoms in the hydrocarbon group as the monovalent organic group represented by the formula (I) is preferably 1 to 20, more preferably 1 to 12, even more preferably 1 to 10, and still more preferably 2 to 8.

[0034] R １Ｘ ~R ４Ｘ The number of carbon atoms in the alkyl group as a monovalent organic group represented by the formula (I) is preferably 1 to 20, more preferably 1 to 12, even more preferably 1 to 10, and still more preferably 2 to 8.

[0035] R １Ｘ ~R ４Ｘ The number of carbon atoms in the aromatic hydrocarbon group as the monovalent organic group represented by the formula (I) is preferably 6 to 20, more preferably 6 to 16, and even more preferably 6 to 12. The aromatic hydrocarbon group is preferably a phenyl group or a naphthyl group.

[0036] R １Ｘ , R ２Ｘ , R ３Ｘ , and R ４Ｘ It is preferable that at least one of R is an alkyl group. More preferably, R １Ｘ , R ２Ｘ , R ３Ｘ , and R ４Ｘ All of the groups are alkyl groups.

[0037] The ionic boron compound may contain elements other than the boron-containing anion and the counter cation. The total proportion of the boron-containing anion and the counter cation in the ionic boron compound is preferably 80% by mass or more, more preferably 90% by mass or more. The total proportion of the boron-containing anion and the counter cation in the ionic boron compound may be 100% by mass.

[0038] <Photosensitizer (1)> The photopolymerization initiator of the present disclosure contains a photosensitizer (1). The photosensitizer (1) is at least one selected from the group consisting of 1,2-diketone compounds and compounds represented by the formula (A) described below.

[0039] (1,2-diketone compounds) Examples of 1,2-diketone compounds include camphorquinone (hereinafter also referred to as "CQ"), benzil, 2,3-pentanedione, 1,2-indandione, etc. As the 1,2-diketone compound, camphorquinone is particularly preferred.

[0040] (Compound Represented by Formula (A)) Formula (A) is as follows.

[0041]

[0042] In formula (A), R １Ａ and R ２Ａ are each independently an aromatic hydrocarbon group which may have a substituent.

[0043] In formula (A), R １Ａ and R ２Ａ The aromatic hydrocarbon group in the aromatic hydrocarbon group represented by each of the following formulae, which may have a substituent, is preferably a phenyl group or a naphthyl group, and more preferably a phenyl group.

[0044] In formula (A), R １Ａ and R ２Ａ As the substituent in the aromatic hydrocarbon group represented by each of the formulas below, which may have a substituent, a substituent containing a heteroatom and a carbon atom is preferred. The heteroatom is preferably an oxygen atom or a sulfur atom. As the substituent containing a heteroatom and a carbon atom, an alkoxy group having 1 to 6 carbon atoms or an alkylthio group having 1 to 6 carbon atoms is more preferred, an alkoxy group having 1 to 3 carbon atoms or an alkylthio group having 1 to 3 carbon atoms is even more preferred, and a methoxy group or a methylthio group is even more preferred.

[0045] In formula (A), R １Ａ and R ２Ａ The aromatic hydrocarbon group represented by each of the following formulas, which may have a substituent, is preferably an aromatic hydrocarbon group having at least one substituent, and more preferably an aromatic hydrocarbon group having at least one substituent containing a hetero atom. １Ａ or R ２ＡWhen is an aromatic hydrocarbon group having two or more substituents, the two substituents may be bonded to each other to form a ring (for example, a heterocycle).

[0046] R in formula (A) １Ａ and R ２Ａ are each preferably independently a phenyl group having at least one heteroatom-containing substituent, and more preferably a phenyl group having one heteroatom-containing substituent, or a phenyl group having two heteroatom-containing substituents which are bonded to each other to form a heterocycle. １Ａ and R ２Ａ are particularly preferably each independently a methoxyphenyl group, a methylthiophenyl group, or a benzodioxolyl group.

[0047] The photosensitizer (1) preferably contains a 1,2-diketone compound, more preferably camphorquinone. In this case, the proportion of the 1,2-diketone compound (preferably camphorquinone) in the entire photosensitizer (1) is preferably 50% by mass to 100% by mass, more preferably 60% by mass to 100% by mass, and even more preferably 80% by mass to 100% by mass.

[0048] In the photopolymerization initiator of the present disclosure, the content of the photosensitizer (1) relative to the total content of the ionic boron compound and the photosensitizer (1) is preferably 3% by mass to 50% by mass, more preferably 5% by mass to 40% by mass, even more preferably 10% by mass to 30% by mass, and still more preferably 15% by mass to 25% by mass.

[0049] The photopolymerization initiator of the present disclosure may or may not contain components other than the ionic boron compound and the photosensitizer (1). The total proportion of the ionic boron compound and the photosensitizer (1) in the entire photopolymerization initiator of the present disclosure is preferably 50% by mass to 100% by mass, more preferably 60% by mass to 100% by mass, and even more preferably 80% by mass to 100% by mass.

[0050] <Preferred Uses> The use of the photopolymerization initiator of the present disclosure is not particularly limited, and it can be applied to any use in which an improvement in the polymerization depth of a photocurable composition is required. For example, the photopolymerization initiator of the present disclosure is preferably a photopolymerization initiator for dental materials (i.e., a photopolymerization initiator contained in a photocurable composition for dental materials).

[0051] [Photocurable Composition] The photocurable composition of the present disclosure contains the photopolymerization initiator of the present disclosure and a monomer, and therefore has an excellent polymerization depth of the monomer.

[0052] <Photopolymerization initiator> The photocurable composition of the present disclosure contains the photopolymerization initiator of the present disclosure described above. The photocurable composition of the present disclosure may contain only one type of photopolymerization initiator of the present disclosure, or two or more types of photopolymerization initiators. The content of the photopolymerization initiator of the present disclosure contained in the photocurable composition of the present disclosure is preferably 1% by mass to 30% by mass, more preferably 2% by mass to 25% by mass, and even more preferably 3% by mass to 20% by mass, based on the total amount of monomers.

[0053] <Monomer> The photocurable composition of the present disclosure contains a monomer. The photocurable composition of the present disclosure may contain only one type of monomer, or two or more types of monomers.

[0054] As the monomer, a compound containing a radical polymerizable group is preferably used. As the radical polymerizable group, a group containing an ethylenic double bond is preferred, and a (meth)acryloyl group is particularly preferred.

[0055] The monomer preferably contains at least one (meth)acrylate compound. In this case, the proportion of the (meth)acrylate compound in the monomer is preferably 60% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more.

[0056] Examples of the (meth)acrylate compound include monofunctional (meth)acrylate compounds and difunctional or higher functional (meth)acrylate compounds. The (meth)acrylate compound preferably contains a difunctional or higher functional (meth)acrylate compound, more preferably contains a difunctional to hexafunctional (meth)acrylate compound, even more preferably contains a difunctional to tetrafunctional (meth)acrylate compound, and particularly preferably contains a difunctional (meth)acrylate compound (i.e., a di(meth)acrylate compound).

[0057] The bifunctional (meth)acrylate compound (i.e., di(meth)acrylate compound) is not particularly limited, and examples thereof include urethane di(meth)acrylate, neopentyl di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,8-octanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetrapropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 2,2-bis[4-(3-(meth)acryloyloxy-2-hydroxypropoxy)phenyl]propane, ethylene oxide-modified bisphenol A di(meth)acrylate, propylene oxide-modified bisphenol A di(meth)acrylate, and the like.

[0058] The proportion of the di(meth)acrylate compound in the monomer is preferably 60% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more.

[0059] The proportion of the di(meth)acrylate compound in the (meth)acrylate compound is preferably 60% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more.

[0060] The urethane di(meth)acrylate is preferably a reaction product of an isocyanate having two or more isocyanate groups and a (meth)acrylate having a hydroxy group (for example, hydroxyethyl methacrylate (HEMA)). The isocyanate having two or more isocyanate groups is preferably at least one selected from the group consisting of hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, pentamethylene diisocyanate, m-xylylene diisocyanate, 1,3-tetramethylxylylene diisocyanate, isophorone diisocyanate, bis(isocyanatemethyl)cyclohexane, bis(isocyanatecyclohexyl)methane, 2,5-bis(isocyanatemethyl)bicyclo-[2.2.1]-heptane, 2,6-bis(isocyanatemethyl)bicyclo-[2.2.1]-heptane, tolylene diisocyanate, phenylene diisocyanate, and 4,4'-diphenylmethane diisocyanate. The (meth)acrylate having a hydroxy group is preferably at least one selected from the group consisting of 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 1,4-cyclohexanedimethanol mono(meth)acrylate.

[0061] For example, a urethane di(meth)acrylate that is the reaction product of a mixture of 2,2,4-trimethylhexamethylene diisocyanate and 2,4,4-trimethylhexamethylene diisocyanate with hydroxyethyl methacrylate (HEMA) is sometimes referred to as di-HEMA trimethylhexyl dicarbamate or di-HEMA trimethylhexyl dicarbamate.

[0062] The proportion of urethane di(meth)acrylate in the monomers is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 80% by mass or more.

[0063] For the monomer, for example, JP-A-11-315059, JP-A-2001-70437, JP-A-2011-105722, JP-A-2000-204069, JP-T-2013-544823, WO 2016 / 125758, WO 2015 / 119163 and other known documents may be referred to as appropriate.

[0064] The content of the monomer in the photocurable composition according to the present disclosure is preferably 10% by mass or more, more preferably 10% by mass to 80% by mass, even more preferably 15% by mass to 60% by mass, and still more preferably 15% by mass to 50% by mass, relative to the total amount of the photocurable composition.

[0065] <Filler> The photocurable composition of the present disclosure may contain a filler as needed. As the filler, for example, a general filler used in the dental field can be used. Fillers are generally broadly classified into organic fillers and inorganic fillers.

[0066] Examples of organic fillers include fine powders of polymethyl methacrylate, polyethyl methacrylate, methyl methacrylate-ethyl methacrylate copolymer, crosslinked polymethyl methacrylate, crosslinked polyethyl methacrylate, ethylene-vinyl acetate copolymer, styrene-butadiene copolymer, and the like.

[0067] Examples of inorganic fillers include fine powders of various glasses (mainly composed of silicon dioxide and optionally containing oxides of heavy metals, boron, aluminum, etc.), various ceramics, diatomaceous earth, kaolin, clay minerals (montmorillonite, etc.), activated clay, synthetic zeolite, mica, calcium fluoride, ytterbium fluoride, calcium phosphate, barium sulfate, zirconium dioxide, titanium dioxide, hydroxyapatite, etc. Specific examples of such inorganic fillers include barium borosilicate glass (Kimble Raysorb T3000, Schott 8235, Schott GM27884, Schott GM39923, etc.), strontium boroaluminosilicate glass (Raysorb T4000, Schott G018-093, Schott GM32087, etc.), lanthanum glass (Scott GM31684, etc.), fluoroaluminosilicate glass (Scott G018-091, Schott G018-117, etc.), and boroaluminosilicate glass containing zirconium, cesium, etc. (Scott G018-307, G018-308, G018-310, etc.).

[0068] Alternatively, an organic-inorganic composite filler may be used which is obtained by adding a monomer to an inorganic filler in advance, forming a paste, polymerizing and curing it, and then pulverizing it.

[0069] Furthermore, a photocurable composition containing microfillers with a particle size of 0.1 μm or less is one of the preferred embodiments for use as a photocurable composition for dental materials. Preferred materials for such small particle size fillers include silica (e.g., Aerosil), alumina, zirconia, and titania.

[0070] These fillers may be surface-treated with a surface treatment agent such as a silane coupling agent depending on the purpose. Examples of the surface treatment agent include known silane coupling agents, such as methacryloxyalkyltrimethoxysilane (number of carbon atoms between the methacryloxy group and the silicon atom: 3 to 12), methacryloxyalkyltriethoxysilane (number of carbon atoms between the methacryloxy group and the silicon atom: 3 to 12), vinyltrimethoxysilane, vinylethoxysilane, vinyltriacetoxysilane, and other organosilicon compounds.

[0071] The content of the filler in the photocurable composition according to the present disclosure is preferably 10% by mass or more, more preferably 30% by mass or more, and even more preferably 50% by mass, based on the total amount of the photocurable composition. The upper limit of the filler content, depending on the content of other components, is, for example, 90% by mass or less, 80% by mass or less, or 70% by mass or less, based on the total amount of the photocurable composition.

[0072] <Other Components> The photocurable composition of the present disclosure may contain other components in addition to the components described above, as necessary. Examples of other components include polymerization inhibitors, non-polymerizable diluents (e.g., water), colorants (e.g., pigments or dyes), reinforcing materials (e.g., fibers), bactericides, disinfectants, stabilizers, preservatives, etc. For other components, reference may be made to the descriptions in known documents such as JP-A-11-315059, JP-A-2001-70437, JP-A-2011-105722, JP-A-2000-204069, JP-A-2013-544823, WO 2016 / 125758, and WO 2015 / 119163, as appropriate.

[0073] The photocurable composition of the present disclosure may not contain an aromatic hydrocarbon amine compound, or if it does contain an aromatic hydrocarbon amine compound, the content of the aromatic hydrocarbon amine compound relative to the total amount of the photocurable composition may be less than 0.01% by mass (or less than 0.001% by mass). Even in these cases, as described above, the photocurable composition of the present disclosure exhibits excellent polymerization depth due to the action of the ionic boron compound in the photopolymerization initiator. In the present disclosure, "aromatic hydrocarbon amine compound" refers to an amine containing an aromatic hydrocarbon structure. Examples of the aromatic hydrocarbon amine compound include aniline, toluidine, N-methylaniline, N-methyl-p-toluidine, N-phenylglycine, N-tolylglycine, N,N-(3-methacryloyloxy-2-hydroxypropyl)phenylglycine (NPG-GMA), N,N-dimethylaniline, N,N-dibenzylaniline, N,N-dimethyl-p-toluidine, N,N-diethyl-p-toluidine, N,N-di(2-hydroxyethyl)-p-toluidine, N,N-dimethyl-p-ethylaniline, N,N-dimethyl-p-isopropylaniline, N,N-dimethyl-p-tert-butylaniline, N,N-dimethylanisidine, N,N-dimethylxylidine, N,N-dimethyl-3,5-di-t-butylaniline, N,N-dimethyl-p-chloroaniline, and N,N-dimethyl-p-fluoroaniline.

[0074] <Preferred Uses> There are no particular limitations on the uses of the photocurable composition of the present disclosure. The photocurable composition of the present disclosure can be used, for example, as a paint, a coating film-forming composition, a dental material, or a component in a dental material.

[0075] The photocurable composition of the present disclosure is preferably a photocurable composition for use as a dental material. Here, the photocurable composition for use as a dental material means a photocurable composition used as a dental material or as a component in a dental material.

[0076] [Dental Material] The dental material of the present disclosure includes at least one of the above-described photocurable composition of the present disclosure and a cured product of the photocurable composition. The dental material of the present disclosure may also include other components as necessary.

[0077] Examples of dental materials disclosed herein include dental restorative composite resins, denture base resins, denture base lining materials, impression materials, luting materials (resin cements, resin-added glass ionomer cements, etc.), dental adhesives (orthodontic adhesives, cavity application adhesives, etc.), fissure sealants, CAD / CAM resin blocks, temporary crowns, artificial tooth materials, etc. Examples of dental restorative composite resins include dental crown composite resins, caries cavity filling composite resins, abutment buildup composite resins, filling and restorative composite resins, etc.

[0078] The dental material of the present disclosure is particularly preferably a dental restorative composite resin. As described above, the photocurable composition of the present disclosure has excellent polymerization depth. Therefore, when the dental material of the present disclosure is a dental restorative composite resin, excellent curing performance (particularly curing performance when irradiated with visible light) is exhibited from the surface to the deep portion of the dental restorative composite resin filled in a tooth defect or the like.

[0079] Examples of the present disclosure will be shown below, but the present disclosure is not limited to the following examples. Each component used in the examples is shown below (where appropriate, the structure of the compound is also shown).

[0080] <Monomers> SR540: Epoxidized (4) bisphenol A dimethacrylate UDMA: Dicarbamic acid di-HEMA trimethylhexyl

[0081] <Polymerization inhibitor> BHT: dibutylhydroxytoluene

[0082] <Non-polymerizable diluent> H ２ O: water

[0083] <Filler> YBF100: ytterbium fluoride manufactured by SG Japan, median diameter 100 nm GM27884: barium borosilicate glass manufactured by Shott, median diameter 1.5 μm

[0084] <Photosensitizer (1)> CQ: camphorquinone MOB-AC: bis(methoxyphenyl)pentadienone MTB-AC: bis((methylthio)phenyl)pentadienone BDO-AC: bis(benzodioxoleyl)pentadienone

[0085]

[0086] <Ionic boron compounds> N3B: Karenz (registered trademark) N3B, an organic boron compound manufactured by Resonac, tetrabutylammonium butyltrinaphthyl borate P3B: Karenz (registered trademark) P3B, an organic boron compound manufactured by Resonac, tetrabutylammonium butyltriphenyl borate

[0087]

[0088] <Comparative Compounds> MBI: mercaptobenzimidazole

[0089] Examples 1 to 7 and Comparative Examples 1 to 4 Preparation of Photocurable Compositions Photocurable compositions of Examples 1 to 7 and Comparative Examples 1 to 4 were prepared using the components shown in Tables 1 to 5. The numbers in the component columns shown in Tables 1 to 5 indicate the amount (parts by mass) of each component. Blank cells in Tables 1 to 5 indicate that the corresponding component was not contained.

[0090] <Evaluation of Polymerization Depth> The polymerization depth of each of the photocurable compositions of Examples 1 to 7 and Comparative Examples 1 to 4 was evaluated using the following method. A metal mold with a hole 4 mm in diameter and 15 mm in depth was prepared, and the photocurable composition was poured into the hole. The exposed surface of the photocurable composition poured into the hole (i.e., the surface in contact with air) was covered with a 50 μm thick PET film (polyethylene terephthalate film), and the photocurable composition was irradiated with ultraviolet light through the PET film for 20 seconds. The ultraviolet light irradiation was performed using a Kulzer Translux 2wave. In this manner, the photocurable composition was cured by polymerizing the monomers in the photocurable composition, yielding a cured product. The resulting cured product was removed from the hole, and the length (mm) of the removed cured product was measured with a vernier caliper. The measured length (mm) of the cured product was taken as the polymerization depth (mm) of the photocurable composition. The results are shown in Table 1.

[0091] Furthermore, for Examples 1 to 5, the ratio of the polymerization depth to that of the corresponding Comparative Example is shown. Here, the Comparative Example corresponding to each Example means a Comparative Example in which the ionic boron compound in each Example is replaced with a Comparative Compound. The ratio of the polymerization depth to that of the corresponding Comparative Example indicates the extent to which the polymerization depth is improved by replacing the Comparative Compound in the corresponding Comparative Example with the ionic boron compound.

[0092]

[0093]

[0094]

[0095]

[0096]

[0097] As shown in Tables 1 to 5, each of the Examples in which an ionic boron compound was used as a component of the photopolymerization initiator showed an improved polymerization depth compared to the corresponding Comparative Example (i.e., an Example in which the ionic boron compound was replaced with a comparative compound).

[0098] The disclosure of Japanese Patent Application No. 2023-127364, filed on August 3, 2023, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. A photopolymerization initiator comprising: an ionic boron compound containing a boron-containing anion and a counter cation for the boron-containing anion; and a photosensitizer (1) which is at least one selected from the group consisting of 1,2-diketone compounds and compounds represented by the following formula (A): [In formula (A), R １Ａ and R ２Ａ each independently represents an aromatic hydrocarbon group which may have a substituent.

2. The photopolymerization initiator according to claim 1, wherein the boron-containing anion is an anion represented by the following formula (B): [In formula (B), R １Ｂ , R ２Ｂ , R ３Ｂ , and R ４Ｂ are each independently a monovalent organic group.

3. R １Ｂ , R ２Ｂ , R ３Ｂ , and R ４Ｂ The photopolymerization initiator according to claim 2 , wherein at least one of the following is an alkyl group:

4. The photopolymerization initiator according to claim 1, wherein the counter cation is a quaternary ammonium cation.

5. The photopolymerization initiator according to claim 1, wherein the 1,2-diketone compound is camphorquinone.

6. The R in the formula (A) １Ａ and the R ２Ａ The photopolymerization initiator according to claim 1 , wherein each of the is independently a phenyl group having at least one substituent containing a heteroatom.

7. The photopolymerization initiator according to claim 1, wherein the content of the photosensitizer (1) relative to the total content of the ionic boron compound and the photosensitizer (1) is 5% by mass to 40% by mass.

8. A photocurable composition comprising the photopolymerization initiator according to any one of claims 1 to 7 and a monomer.

9. The photocurable composition according to claim 8, further comprising a filler.

10. The photocurable composition according to claim 8, which does not contain an aromatic hydrocarbon amine compound, or if it contains an aromatic hydrocarbon amine compound, the content of the aromatic hydrocarbon amine compound relative to the total amount of the photocurable composition is less than 0.01 mass%.

11. The photocurable composition according to claim 8, which is a dental material.

12. A dental material comprising at least one of the photocurable composition according to claim 8 and a cured product of said photocurable composition.

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