JP7684040B2 - Photoinitiators containing aryl iodonium salts for dental light-curable compositions - Google Patents

Description

The present invention relates to a dental photocurable composition and a photopolymerization initiator used in the dental photocurable composition.

In the dental field, dental photocurable compositions are used for intraoral treatment and are applied in dental adhesives, dental composite resins, dental core construction materials, dental resin cements, dental surface coating materials, dental pit and fissure sealants, dental manicures, etc.

Patent No. 4093974 Patent No. 4596786

However, the photopolymerization initiators used in dental photocurable compositions were not able to provide sufficient physical properties.

Patent Documents 1 and 2 propose a photopolymerization initiator that contains a photoacid generator (a triazine compound or a specific aryl iodonium salt), a sensitizer, and an electron donor compound, but they are unable to obtain sufficient physical properties.

There is a demand for a photopolymerization initiator that exhibits excellent sensitivity to photopolymerization and can ensure sufficient pot life in ambient light, and the objective of the present invention is to provide a dental photocurable composition that contains the photopolymerization initiator.

The present invention relates to a photopolymerization initiator (c) used in a dental photocurable composition,
(c-1) a photosensitizer, (c-2) a polymerization accelerator, and (c-3) a compound of the formula (1):

(wherein R1 represents an organic group bonded to I, R2 represents an alkyl group in which some of the hydrogen atoms are substituted with fluorine atoms, and b represents the number of alkyl groups and is an integer from 1 to 5).

The photopolymerization initiator of the present invention makes it possible to obtain a dental photocurable composition that exhibits excellent sensitivity to irradiated light and ensures a sufficient pot life against ambient light. In addition, a dental photocurable composition containing the photopolymerization initiator of the present invention has excellent bending strength.

In the (c) photopolymerization initiator of the present invention, the formula (1) of (c-3) may be an aryl iodonium salt in which R2 is an alkyl group in which 80% or more of the hydrogen atoms are substituted with fluorine atoms.

The dental photocurable composition may include the photopolymerization initiator (c) and the polymerizable monomer (a).
The dental photocurable composition may include the photopolymerization initiator (c), the polymerizable monomer (a), and the filler (b).

The dental photocurable composition may contain, relative to 100 parts by mass of the polymerizable monomer (a), a photopolymerization initiator (c) of 0.1 to 5 parts by mass of a photosensitizer (c-1), 0.01 to 10 parts by mass of a polymerization accelerator (c-2), and 0.01 to 10 parts by mass of an aryl iodonium salt represented by formula (1) (c-3).
The dental photocurable composition may contain 10 to 1,900 parts by weight of the filler (b) relative to 100 parts by weight of the polymerizable monomer (a).

The dental photocurable composition may be a dental adhesive, a dental composite resin, a dental core construction material, a dental resin cement, a dental surface coating material, a dental pit and fissure sealant, or a dental manicure material.

Each component of the dental photocurable composition of the present invention will be described in detail below.
The present invention relates to a photopolymerization initiator and a dental photocurable composition containing the photopolymerization initiator. The dental photocurable composition of the present invention is used as a dental adhesive, a dental composite resin, a dental core material, a dental resin cement, a dental surface coating material, a dental pit and fissure sealant, and a dental manicure material.

In dental clinical practice, in order to restore the aesthetics and functions of teeth that have been damaged by caries or fractures, direct restoration with dental composite resins or indirect restoration in which a prosthetic device made of ceramics or hard resin is attached using dental resin cement after pretreatment with dental adhesives is performed. Dental composite resins and dental resin cements are prepared by mixing a resin matrix made of several types of polymerizable monomers, various fillers such as inorganic fillers and organic-inorganic composite fillers, and a polymerization initiator to form a uniform paste. Dental filling composite resins are filled into teeth in an uncured paste state, and are then given the anatomical shape of natural teeth with dental instruments or other dental tools, and then hardened by irradiation with light from a dental light irradiator or the like. The light irradiated from the light irradiator is generally a light source with an output of about 100 to 2000 mW/ ^cm2 in the wavelength range of about 360 to 500 nm. On the other hand, dental resin cement is used when bonding a prosthetic device to a cavity or an abutment tooth, and is hardened by irradiating it with light after the prosthetic device is attached to the cavity or the abutment tooth.

As photopolymerization initiators for dental composite resins and dental resin cements, photosensitizers and systems combining photosensitizers with appropriate photopolymerization accelerators are widely used. Acylphosphine oxide compounds and α-diketone compounds are known as photosensitizers, and α-diketone compounds in particular have the ability to initiate polymerization in the visible light wavelength range, which has little effect on the human body. Tertiary amine compounds are also well known as polymerization accelerators to be combined with photosensitizers, and the combination of α-diketone compounds and tertiary amine compounds has high polymerization activity in response to irradiated light, and is therefore used in the field of dental materials. Dental photocurable compositions containing the photopolymerization initiators exhibit excellent mechanical properties, such as hardness, bending strength, and compressive strength, required for dental filling composite resins and dental resin cements.

However, when the combination of the above-mentioned α-diketone compound and tertiary amine compound is used as a photopolymerization initiator, the problem of poor environmental light stability arises. In other words, the procedure is performed under white light (ambient light) such as a dental light that the surgeon uses to illuminate the oral cavity or an indoor light such as a fluorescent lamp. However, when only the above-mentioned combination of the α-diketone compound and tertiary amine compound is used as a photopolymerization initiator, it shows high sensitivity not only to the irradiated light but also to the ambient light, so that during operations such as filling, building up, and fitting, the hardening gradually progresses, causing the viscosity of the paste to increase, making the operation difficult.

In order to solve the above problems, if the amount of photopolymerization initiator added is reduced or the amount of polymerization inhibitor added is increased, the stability against environmental light is improved, but the sensitivity to irradiated light is also reduced at the same time. Therefore, even if irradiated with irradiated light for a long time, sufficient curing does not proceed, and the mechanical strength of the cured body is reduced, or a large amount of unpolymerized surface layer remains, causing problems such as coloring over time in the oral cavity. Another problem is that when a tertiary amine compound is blended as a polymerization accelerator, the cured body is prone to discoloration when exposed to sunlight, etc. When used as a dental adhesive, there are issues such as a decrease in adhesive strength and discoloration of the adhesive layer after curing when subjected to a thermal load simulating the oral cavity. In this way, it was difficult to achieve both characteristics, such as environmental light stability and high polymerization activity against irradiated light.

As a photopolymerization initiator, a photopolymerization initiator containing a specific aryliodonium salt, a sensitizer, and an electron donor compound has been proposed, but sufficient physical properties could not be obtained. Photopolymerization initiators containing aryliodonium salts have the following problems. First, conventional aryliodonium salts have low solubility in polymerizable monomers, and are limited to being mixed at extremely low concentrations due to the risk of precipitation, etc., assuming a clinical use temperature. Therefore, the photopolymerization activity is insufficient. Furthermore, by using aryliodonium salts in combination with a polymerization accelerator such as a tertiary amine compound, the photosensitivity increases, so that the stability to ambient light is low, the operable time is significantly shortened, and discoloration of the cured body when exposed to sunlight, etc. is further promoted.
Although the detailed mechanism by which the discoloration occurs is unknown, it is speculated that the discoloration is promoted by the cationic moiety contained in the structure of the photoacid generator and the polymerization accelerator, such as a tertiary amine compound or an organometallic compound, forming a salt or interacting with each other.

However, according to the inventors' investigations, they found that when a photopolymerization initiator containing an aryl iodonium salt having a specific structure is used in a dental photocurable composition, the solubility in the polymerizable monomer is improved, there is no risk of precipitation, appropriate photosensitivity is exhibited, and discoloration when exposed to sunlight, etc. is significantly reduced, which led to the completion of the present invention.

As described above, the present invention provides a dental photocurable composition that exhibits high polymerization activity in response to irradiated light, and when applied to, for example, dental filling composite resins or dental resin cements, has aesthetic properties and mechanical properties (hardness, bending strength, compressive strength, etc.), and when applied as an adhesive, has durable adhesive strength, as well as excellent long-term storage stability, environmental light stability, and color stability.

<(a) Polymerizable Monomer>
The polymerizable monomer (a) that can be used in the present invention can be any known monofunctional and/or polyfunctional polymerizable monomer that is generally used in the dental field, without any restrictions. A representative example of a polymerizable monomer that is generally preferably used is a (meth)acrylate monomer or a (meth)acryloyl polymerizable monomer having an acryloyl group and/or a methacryloyl group. In the present invention, (meth)acrylate or (meth)acryloyl is used to collectively represent both an acryloyl group-containing polymerizable monomer and a methacryloyl group-containing polymerizable monomer.

Specific examples of (meth)acrylate polymerizable monomers that can be used as the (a) polymerizable monomer are as follows:
Examples of monofunctional monomers include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate (n-butyl (meth)acrylate, i-butyl (meth)acrylate), hexyl (meth)acrylate, dicyclopentenyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, glycidyl (meth)acrylate, lauryl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, and allyl (meth)acrylate. Examples of the suitable alkyl acrylates include (meth)acrylic acid esters such as 2-ethoxyethyl (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, glycerol (meth)acrylate, and isobornyl (meth)acrylate; silane compounds such as γ-(meth)acryloyloxypropyltrimethoxysilane and γ-(meth)acryloyloxypropyltriethoxysilane; and nitrogen-containing compounds such as 2-(N,N-dimethylamino)ethyl (meth)acrylate, N-methylol (meth)acrylamide, and diacetone (meth)acrylamide.

Examples of aromatic bifunctional monomers include 2,2-bis(4-(meth)acryloyloxyphenyl)propane, 2,2-bis(4-(3-(meth)acryloyloxy-2-hydroxypropoxy)phenyl)propane, 2,2-bis(4-(meth)acryloyloxyethoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxydiethoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxytetraethoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxypentaethoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxydipropoxy phenyl)propane, 2(4-(meth)acryloyloxyethoxyphenyl)-2(4-(meth)acryloyloxydiethoxyphenyl)propane, 2(4-(meth)acryloyloxydiethoxyphenyl)-2(4-(meth)acryloyloxytriethoxyphenyl)propane, 2(4-(meth)acryloyloxydipropoxyphenyl)-2(4-(meth)acryloyloxytriethoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxydipropoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxyisopropoxyphenyl)propane, etc.

Examples of aliphatic bifunctional monomers include 2-hydroxy-3-acryloyloxypropyl methacrylate, hydroxypivalic acid neopentyl glycol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, propylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and glycerol di(meth)acrylate.

Examples of trifunctional monomers include trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, trimethylolmethane tri(meth)acrylate, and pentaerythritol tri(meth)acrylate.

Examples of tetrafunctional monomers include pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, etc.

Examples of urethane-based polymerizable monomers include di(meth)acrylates having bifunctional or trifunctional or higher urethane bonds derived from adducts of polymerizable monomers having hydroxyl groups, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 3-chloro-2-hydroxypropyl (meth)acrylate, with diisocyanate compounds, such as methylcyclohexane diisocyanate, methylene bis(4-cyclohexyl isocyanate), hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, isophorone diisocyanate, diisocyanate methylmethylbenzene, and 4,4-diphenylmethane diisocyanate.

There is no restriction on the use of oligomers or prepolymers having at least one polymerizable group in the molecule other than these (meth)acrylate polymerizable monomers. In addition, there is no problem even if the same molecule has a substituent such as a fluoro group.
The above-described polymerizable monomers can be used alone or in combination of two or more.

The (a) polymerizable monomer contained in the dental photocurable composition of the present invention may contain a known acidic group-containing polymerizable monomer in order to impart adhesiveness to tooth structure or prosthetic devices. Specific examples of the acidic group possessed by the acidic group-containing polymerizable monomer include a phosphate group, a pyrophosphate group, a phosphonic acid group, a carboxylic acid group, a sulfonic acid group, a thiophosphate group, etc., and the acidic group-containing polymerizable monomer refers to a polymerizable monomer having at least one of these groups, and is preferably 10-methacryloyloxydecyl dihydrogen phosphate, 6-methacryloxyhexyl phosphonoacetate, or 4-methacryloxyethyl trimellitic acid. From the viewpoint of imparting adhesiveness, the amount of the polymerizable monomer may be 5 to 60 parts by weight, more preferably 10 to 50 parts by weight, out of a total of 100 parts by weight of the polymerizable monomers in the composition.

The dental photocurable composition of the present invention may contain a silane coupling agent to impart adhesion to glass ceramics. Any known silane coupling agent may be used without restriction, but 3-methacryloxypropyltrimethoxysilane may also be used. From the viewpoint of imparting adhesion, the compounding amount may be 0.5 to 10 parts by weight out of 100 parts by weight of the total amount of polymerizable monomers in the composition, for example, 0.5 to 5 parts by weight.

<(b) Filler>
As the filler (b) that can be used in the present invention, any known filler that is generally used in dental composite materials can be used.

(b) Types of fillers include inorganic fillers, organic fillers, and organic-inorganic composite fillers, and they can be used alone or in combination regardless of the type of filler.

The filler is not particularly limited, but may be silica glass, fluoroaluminosilicate glass, fluoroaluminoborosilicate glass, other silicate glasses, zirconium silicate glasses including zirconia, and zirconium silicate may be used.

The above-mentioned (b) filler can be treated with a surface treatment material, typically a silane coupling material, for the purpose of improving the affinity with the polymerizable monomer, the dispersibility in the polymerizable monomer, and the mechanical strength and water resistance of the cured body. Such surface treatment materials and surface treatment methods are not particularly limited, and known methods can be used without limitation. The silane coupling material used for the surface treatment of the filler may be methyltrimethoxysilane, methyltriethoxysilane, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyltris(β-methoxyethoxy)silane, γ-methacryloyloxypropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, or hexamethyldisilazane. In addition to the silane coupling material, the surface treatment of the filler can be performed by a method using a titanate-based coupling material or an aluminate-based coupling material. The amount of surface treatment agent applied to the filler is preferably 0.01 to 30 parts by weight, and more preferably 0.5 to 20 parts by weight, per 100 parts by weight of the filler before treatment.

The shape of the filler is not particularly limited, and amorphous and spherical fillers can be used. The average particle size of the filler is preferably in the range of 0.01 μm to 50 μm, more preferably 0.1 μm to 30 μm, even more preferably 0.5 μm to 20 μm, and even more preferably 0.5 μm to 10 μm.

The amount of the filler (b) per 100 parts by weight of the polymerizable monomer (a) is preferably 10 to 1900 parts by weight, more preferably 30 to 900 parts by weight, and even more preferably 100 to 900 parts by weight. If more than 1900 parts by weight is added, the composition will have a hard paste-like texture and will be difficult to handle.

<(c) Photopolymerization initiator>
<(c-1) Photosensitizer>
The photosensitizer (c-1) used in the dental photocurable composition of the present invention is not particularly limited, and any known compound generally used in the dental field can be used without any restrictions.

Specific examples of photosensitizers include α-diketones such as benzil, camphorquinone, α-naphthyl, acetonaphthene, p,p'-dimethoxybenzyl, p,p'-dichlorobenzylacetyl, pentanedione, 1,2-phenanthrenequinone, 1,4-phenanthrenequinone, 3,4-phenanthrenequinone, 9,10-phenanthrenequinone, and naphthoquinone; benzoin, benzoin methyl ether, and benzoin ethyl ether; thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2-isopropylthioxanthone, 2-methoxythioxanthone, 2-hydroxythioxanthone, 2,4-diethylthioxanthone, and 2,4-diisopropylthioxanthone; benzophenones such as benzophenone, p-chlorobenzophenone, and p-methoxybenzophenone; 2,4,6-trimethylbenzophenone; Examples of the acylphosphine oxides include acylphosphine oxides such as bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, α-aminoacetophenones such as 2-benzyl-dimethylamino-1-(4-morpholinophenyl)-butanone-1 and 2-benzyl-diethylamino-1-(4-morpholinophenyl)-propanone-1, ketals such as benzyl dimethyl ketal, benzyl diethyl ketal, and benzyl (2-methoxyethyl ketal), and titanocenes such as bis(cyclopentadienyl)-bis[2,6-difluoro-3-(1-pyrrolyl)phenyl]-titanium, bis(cyclopentadienyl)-bis(pentanefluorophenyl)-titanium, and bis(cyclopentadienyl)-bis(2,3,5,6-tetrafluoro-4-disiloxyphenyl)-titanium.

The (c-1) photosensitizer used can be appropriately selected depending on the wavelength, intensity, and light exposure time of the light used in the polymerization, as well as the types and amounts of other components to be combined. The photosensitizers can be used alone or in combination of two or more. Among them, α-diketone compounds having a maximum absorption wavelength in the visible light region are preferably used, and camphorquinone may be used in particular.

The amount of the photosensitizer (c-1) is usually preferably 0.01 to 5 parts by weight, more preferably 0.05 to 3 parts by weight, and even more preferably 0.1 to 1 part by weight, per 100 parts by weight of the total amount of the polymerizable monomer (a). If the amount of the photosensitizer is less than 0.01 part by weight, the polymerization activity to the irradiated light is poor and curing is insufficient. If more than 5 parts by weight is used, although sufficient curing properties are obtained, the environmental light stability is shortened and the yellowish color increases.

<(c-2) Polymerization accelerator>
The polymerization accelerator (c-2) used in the dental adhesive composition of the present invention is not particularly limited as long as it has a polymerization accelerator ability, and any known polymerization accelerator generally used in the dental field can be used without any limitation. As the polymerization accelerator, tertiary amine compounds such as aromatic tertiary amine compounds and aliphatic tertiary amine compounds, and organometallic compounds can be used.

Specific examples of the aromatic tertiary amine compounds include N,N-dimethylaniline, N,N-diethylaniline, N,N-di-n-butylaniline, N,N-dibenzylaniline, p-N,N-dimethyl-toluidine, m-N,N-dimethyl-toluidine, p-N,N-diethyl-toluidine, p-bromo-N,N-dimethylaniline, m-chloro-N,N-dimethylaniline, p-dimethylaminobenzaldehyde, p-dimethylaminoacetophenone, p-dimethylaminobenzoic acid, p-di Examples of the compound include methylaminobenzoic acid ethyl ester, p-dimethylaminobenzoic acid amino ester, N,N-dimethylanthranilic acid methyl ester, N,N-dihydroxyethylaniline, p-N,N-dihydroxyethyl-toluidine, p-dimethylaminophenyl alcohol, p-dimethylaminostyrene, N,N-dimethyl-3,5-xylidine, 4-dimethylaminopyridine, N,N-dimethyl-α-naphthylamine, and N,N-dimethyl-β-naphthylamine. In addition, the compound may be, for example, p-N,N-dimethyl-toluidine or p-N,N-dihydroxyethyl-toluidine.

Specific examples of the aliphatic tertiary amine compound include tributylamine, tripropylamine, triethylamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, N,N-dimethylhexylamine, N,N-dimethyldodecylamine, N,N-dimethylstearylamine, N,N-dimethylaminoethyl methacrylate, N,N-diethylaminoethyl methacrylate, 2-(N,N-diisopropylamino)ethyl methacrylate, 2,2'-(n-butylimino)diethanol, N-[3-(dimethylamino)propyl]acrylamide, etc. In addition, for example, N,N-dimethylaminoethyl methacrylate, N,N-diethylaminoethyl methacrylate, or triethanolamine may be used.

The above organometallic compounds are organometallic compounds containing scandium (Sc), titanium (Ti), vanadium (V), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), tin (Sn), zinc (Zn), and zirconia (Zr), and are preferably organometallic compounds containing tin (Sn), vanadium (V), and copper (Cu). Specifically, organometallic compounds containing tin (Sn) include dibutyl-tin-diacetate, dibutyl-tin-dimaleate, dioctyl-tin-dimaleate, dioctyl-tin-dilaurate, dibutyl-tin-dilaurate, dioctyl-tin-diversatate, dioctyl-tin-S,S'-bis-isooctylmercaptoacetate, and tetramethyl-1,3-diacetoxydistannoxane, and organometallic compounds containing vanadium (V) include vanadium acetylacetonate, divana tetroxide, and the like. vanadyl acetylacetonate, vanadium oxide stearate, vanadyl oxalate, vanadyl sulfate, oxo-bis(1-phenyl-1,3-butanedionate)vanadium, bis(maltolato)oxovanadium, vanadium pentoxide, sodium metavanadate, etc., and organometallic compounds containing copper (Cu) include copper acetylacetonate, copper naphthenate, copper octoate, copper acetylacetonate stearate, copper naphthenate, copper octoate, copper stearate, and copper acetate.

The type of polymerization accelerator (c-2) used can be appropriately selected depending on the type and amount of other components to be combined. The polymerization accelerator can be used alone or in combination of two or more types.

The amount of polymerization accelerator (c-2) is usually preferably 0.01 to 10 parts by weight, more preferably 0.05 to 5 parts by weight, per 100 parts by weight of the total amount of polymerizable monomer (a). If the amount of polymerization accelerator is less than 0.01 part by weight, the polymerization promotion ability is poor and curing is likely to be insufficient. If more than 10 parts by weight is used, sufficient curing ability is obtained, but the environmental light stability is shortened and discoloration of the cured product increases.

<(c-3) Aryliodonium Salt>
The aryl iodonium salt (c-3) used in the dental adhesive composition of the present invention is an aryl iodonium salt represented by formula (1).

In the formula, [(R1) ₂ I] ⁺ is the cationic portion, and [(R2) _b PF _6-b ] ^- is the anionic portion. "In the formula, R1 represents an organic group bonded to I, R2 represents an alkyl group in which some of the hydrogen atoms have been replaced with fluorine atoms, and b represents the number of alkyl groups, an integer between 1 and 5."

In formula (1), R1 represents an organic group bonded to I, and R1 may be the same or different. R1 represents an aryl group having 6 to 30 carbon atoms, a heterocyclic group having 4 to 30 carbon atoms, an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 2 to 30 carbon atoms, or an alkynyl group having 2 to 30 carbon atoms, which may be substituted with at least one selected from the group consisting of alkyl, hydroxy, alkoxy, alkylcarbonyl, arylcarbonyl, alkoxycarbonyl, aryloxycarbonyl, arylthiocarbonyl, acyloxy, arylthio, alkylthio, aryl, heterocyclic, aryloxy, alkylsulfinyl, arylsulfinyl, alkylsulfonyl, arylsulfonyl, alkyleneoxy, amino, cyano, nitro, and halogen.

In the above, examples of the aryl group having 6 to 30 carbon atoms include monocyclic aryl groups such as phenyl group, and condensed polycyclic aryl groups such as naphthyl, anthracenyl, phenanthrenyl, pyrenyl, chrysenyl, naphthacenyl, benzanthracenyl, anthraquinolyl, fluorenyl, naphthoquinone, and anthraquinone.

Heterocyclic groups having 4 to 30 carbon atoms include rings containing 1 to 3 heteroatoms such as oxygen, nitrogen, and sulfur, which may be the same or different. Specific examples include monocyclic heterocyclic groups such as thienyl, furanyl, pyranyl, pyrrolyl, oxazolyl, thiazolyl, pyridyl, pyrimidyl, and pyrazinyl, and condensed polycyclic heterocyclic groups such as indolyl, benzofuranyl, isobenzofuranyl, benzothienyl, isobenzothienyl, quinolyl, isoquinolyl, quinoxalinyl, quinazolinyl, carbazolyl, acridinyl, phenothiazinyl, phenazinyl, xanthenyl, thianthrenyl, phenoxazinyl, phenoxathiinyl, chromanyl, isochromanyl, dibenzothienyl, xanthonyl, thioxanthonyl, and dibenzofuranyl.

Examples of alkyl groups having 1 to 30 carbon atoms include linear alkyl groups such as methyl, ethyl, propyl, butyl, hexadecyl, and octadecyl; branched alkyl groups such as isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, neopentyl, tert-pentyl, and isohexyl; and cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl. Examples of alkenyl groups having 2 to 30 carbon atoms include linear or branched groups such as vinyl, allyl, 1-propenyl, isopropenyl, 1-butenyl, 2-butenyl, 3-butenyl, and 1-methyl-1-propenyl. Examples of alkynyl groups having 2 to 30 carbon atoms include linear or branched groups such as ethynyl, 1-propynyl, 2-propynyl, 1-butynyl, 2-butynyl, 3-butynyl, 1-methyl-1-propynyl, and 1-methyl-2-propynyl.

The above aryl group having 6 to 30 carbon atoms, heterocyclic group having 4 to 30 carbon atoms, alkyl group having 1 to 30 carbon atoms, alkenyl group having 2 to 30 carbon atoms, or alkynyl group having 2 to 30 carbon atoms may have at least one type of substituent, and examples of the substituent include linear alkyl groups having 1 to 18 carbon atoms such as methyl, ethyl, propyl, butyl, and octadecyl; branched alkyl groups having 1 to 18 carbon atoms such as isopropyl, isobutyl, sec-butyl, and tert-butyl; cycloalkyl groups having 3 to 18 carbon atoms such as cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl; hydroxy groups; linear or branched alkoxy groups having 1 to 18 carbon atoms such as methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, sec-butoxy, tert-butoxy, and dodecyloxy; Straight-chain or branched alkylcarbonyl groups having 2 to 18 carbon atoms, such as acetyl, propionyl, butanoyl, 2-methylpropionyl, heptanoyl, 2-methylbutanoyl, 3-methylbutanoyl, and octanoyl; arylcarbonyl groups having 7 to 11 carbon atoms, such as benzoyl and naphthoyl; straight-chain or branched alkoxycarbonyl groups having 2 to 19 carbon atoms, such as methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, isopropoxycarbonyl, butoxycarbonyl, isobutoxycarbonyl, sec-butoxycarbonyl, and tert-butoxycarbonyl; aryloxycarbonyl groups having 7 to 11 carbon atoms, such as phenoxycarbonyl and naphthoxycarbonyl; arylthiocarbonyl groups having 7 to 11 carbon atoms, such as phenylthiocarbonyl and naphthoxythiocarbonyl; linear or branched acyloxy groups having 2 to 19 carbon atoms, such as acetoxy, ethylcarbonyloxy, propylcarbonyloxy, isobutylcarbonyloxy, sec-butylcarbonyloxy, tert-butylcarbonyloxy, and octadecylcarbonyloxy; arylthio groups having 6 to 20 carbon atoms, such as phenylthio, biphenylylthio, methylphenylthio, chlorophenylthio, bromophenylthio, fluorophenylthio, hydroxyphenylthio, methoxyphenylthio, naphthylthio, 4-[4-(phenylthio)benzoyl]phenylthio, 4-[4-(phenylthio)phenoxy]phenylthio, 4-[4-(phenylthio)phenyl]phenylthio, 4-(phenylthio)phenylthio, 4-benzoylphenylthio, 4-benzoyl-chlorophenylthio, 4-benzoyl-methylthiophenylthio, 4-(methylthiobenzoyl)phenylthio, and 4-(p-tert-butylbenzoyl)phenylthio; linear or branched alkylthio groups having 1 to 18 carbon atoms, such as methylthio, ethylthio, propylthio, tert-butylthio, neopentylthio, dodecylthio, etc.; aryl groups having 6 to 10 carbon atoms, such as phenyl, tolyl, dimethylphenyl, naphthyl, etc.; heterocyclic groups having 4 to 20 carbon atoms, such as thienyl, furanyl, pyranyl, xanthenyl, chromanyl, isochromanyl, xanthonyl, thioxanthonyl, dibenzofuranyl, etc.; aryloxy groups having 6 to 10 carbon atoms, such as phenoxy, naphthyloxy, etc.; linear or branched alkylsulfinyl groups having 1 to 18 carbon atoms, such as methylsulfinyl, ethylsulfinyl, propylsulfinyl, tert-pentylsulfinyl, octylsulfinyl, etc.; arylsulfinyl groups having 6 to 10 carbon atoms, such as phenylsulfinyl, tolylsulfinyl, naphthylsulfinyl, etc.; Examples of such groups include linear or branched alkylsulfonyl groups having 1 to 18 carbon atoms, such as methylsulfonyl, ethylsulfonyl, propylsulfonyl, isopropylsulfonyl, butylsulfonyl, and octylsulfonyl; arylsulfonyl groups having 6 to 10 carbon atoms, such as phenylsulfonyl, tolylsulfonyl (tosyl group), and naphthylsulfonyl; alkyleneoxy groups; cyano groups; nitro groups; and halogens such as fluorine, chlorine, bromine, and iodine.

In formula (1), R2 represents an alkyl group substituted with a fluorine atom, and may have 1 to 4 carbon atoms. Specific examples of the alkyl group include linear alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, and octyl; branched alkyl groups such as isopropyl, isobutyl, sec-butyl, and tert-butyl; and cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl. R2 may be an alkyl group in which 80% or more of the hydrogen atoms are substituted with fluorine atoms. Furthermore, R2 may be an alkyl group in which 90% or more of the hydrogen atoms are substituted with fluorine atoms. Furthermore, R2 may be an alkyl group in which 100% or more of the hydrogen atoms are substituted with fluorine atoms. If the hydrogen atoms in the alkyl group are not substituted with fluorine atoms, discoloration occurs after exposure to sunlight, etc.

The incorporation of an aryliodonium salt represented by formula (1) inhibits discoloration after exposure and ensures sufficient pot life under ambient light. The mechanism behind this is presumed to be as follows, although the present invention is not limited to a specific theory. The introduction of an alkyl group substituted with a fluorine atom increases the hydrophobicity of the aryliodonium salt. This is also true in the excited state, and since the interaction between the excited aryliodonium salt and the polymerization accelerator is reduced, when the aryliodonium salt itself is excited or is in an excited state due to the energy obtained from the photosensitizer, the transfer of energy or electrons to the polymerization accelerator is suppressed, which is presumed to inhibit discoloration after exposure to sunlight, etc., and ensure sufficient pot life under ambient light.

Particularly preferably, R2 is a straight-chain or branched alkyl group having 1 to 4 carbon atoms in _which all of the hydrogen atoms in the alkyl group are substituted with fluorine _atoms , and specific examples include _CF3 , _CF3CF2 , _{( CF3 ) 2CF} , _CF3CF2CF2 , _CF3CF2CF2CF2 , ( _{CF3 ) 2CFCF2 , CF3CF2} ( _{CF3 )} CF, _and ( _CF3 ) _3C .

In formula (1), the number b of R2 is an integer of 1 to 5, preferably 2 to 4, and particularly preferably 2 or 3. The b R2s may be the same or different.

Specific examples of preferred anion moieties include [( _CF3CF2 ) _3PF3 ] ^- , _[ ( _CF3CF2CF2 ) _{3PF3 ]} ^- , [(( _CF3 ) _2CF ) _{3PF3 ]} - _, [( _{( CF3} ) _2CF ) _2PF4 ] ^- , [(( _CF3 ) _{2CFCF2 ) 3PF3} ] ^{- ,} and [ _{( ( CF3} ) _{2CFCF2 ) 2PF4 ]} - _.

The aryl iodonium salts represented by formula (1) have excellent solubility in polymerizable monomers and polymerization promoting ability, and examples of such salts include diphenyliodonium tris(pentafluoroethyl)trifluorophosphate, ditolyliodonium tris(pentafluoroethyl)trifluorophosphate, bis(4-dodecylphenyl)iodonium tris(pentafluoroethyl)trifluorophosphate, bis(4-methoxyphenyl)iodonium, (4-octyloxyphenyl)phenyliodonium tris(pentafluoroethyl)trifluorophosphate, and bis(4-decyloxy)phenyliodonium tris(pentafluoroethyl)trifluorophosphate. iodonium tris(pentafluoroethyl)trifluorophosphate, 4-(2-hydroxytetradecyloxy)phenylphenyliodonium tris(pentafluoroethyl)trifluorophosphate, 4-isopropylphenyl(p-tolyl)iodonium tris(pentafluoroethyl)trifluorophosphate, 4-isobutylphenyl(p-tolyl)iodonium tris(pentafluoroethyl)trifluorophosphate, bis(4-tert-butylphenyl)iodonium tris(pentafluoroethyl)trifluorophosphate, and bis(4-tert-butylphenyl)iodonium tris(pentafluoropropyl)trifluorophosphate may also be used.

The amount of the aryl iodonium salt (c-3) is usually preferably 0.01 to 10 parts by weight, more preferably 0.05 to 5 parts by weight, or may be, for example, 0.5 to 3 parts by weight, per 100 parts by weight of the total amount of the polymerizable monomer (a). If the amount of the aryl iodonium salt is less than 0.01 parts by weight, the polymerization promotion ability is poor and curing is insufficient. If more than 10 parts by weight is used, although sufficient curing properties are obtained, the environmental light stability is shortened and discoloration increases, such as the cured product taking on a brownish color.

These photopolymerization initiators can be used alone or in combination of two or more kinds. Furthermore, these polymerization initiators can be subjected to secondary treatment such as encapsulation in microcapsules as necessary without any problems. Furthermore, these various types of photopolymerization initiators can be used alone or in combination of two or more kinds, regardless of the polymerization mode or polymerization method.

The dental photocurable composition of the present invention may contain a chemical polymerization initiator in addition to the photopolymerization initiator (c), and any known chemical polymerization initiator may be used without restriction. As the chemical polymerization initiator, thiourea derivatives, organic peroxides having a hydroperoxide group, and sulfinates may be used alone or in combination.

As the thiourea derivative, any known thiourea derivative can be used without any restrictions. Specific examples of thiourea derivatives include dimethylthiourea, diethylthiourea, tetramethylthiourea, (2-pyridyl)thiourea, N-methylthiourea, ethylenethiourea, N-allylthiourea, N-allyl-N'-(2-hydroxyethyl)thiourea, N-benzylthiourea, 1,3-dicyclohexylthiourea, N,N'-diphenylthiourea, 1,3-di(p-tolyl)thiourea, 1-methyl-3-phenylthiourea, N-acetylthiourea, N-benzoylthiourea, diphenylthiourea, dicyclohexylthiourea, etc. Among these, N-acetylthiourea and N-benzoylthiourea may be used. A plurality of types of these thiourea derivatives may be used in combination as necessary. The amount of thiourea derivative to be blended is preferably 0.1 to 4 parts by weight based on the total amount of all polymerizable monomers; if it is less than 0.1 part by weight, the polymerization promotion ability will be insufficient, and if it exceeds 4 parts by weight, storage stability may decrease.

As the organic peroxide having a hydroperoxide group, any known organic peroxide having a hydroperoxide group can be used without limitation. Specific examples of organic peroxides include t-butyl hydroperoxide, cyclohexyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, p-menthane hydroperoxide, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, etc., and cumene hydroperoxide may be used from the viewpoint of reactivity. A combination of multiple types of these organic peroxides may be used as necessary. The amount of the organic peroxide having a hydroperoxide group is preferably 0.1 to 4 parts by weight based on the total amount of all polymerizable monomers. If it is less than 0.1 part by weight, the ability as a polymerization promoter is insufficient, and if it exceeds 4 parts by weight, storage stability may decrease.

Examples of sulfinic acid derivatives include salts (which may be of alkali metals or alkaline earth metals) of p-toluenesulfinic acid, benzenesulfinic acid, 2,4,6-trimethylbenzenesulfinic acid, 2,4,6-triethylbenzenesulfinic acid, 2,4,6-triisopropylbenzenesulfinic acid, etc., and specific examples of salt compounds of these sulfinic acids include sodium p-toluenesulfinate and sodium benzenesulfinate.

<(d) Solvent>
The solvent (d) that can be used in the present invention can be any known solvent used in the dental field without any restrictions. Representative examples of solvents that can be used include water and organic solvents. Among organic solvents, water-soluble volatile organic solvents having a boiling point of 100° C. or less under normal pressure are preferred. Specific examples of such organic solvents include ethanol, methanol, 1-propanol, isopropyl alcohol, acetone, methyl ethyl ketone, 1,2-dimethoxyethane, 1,2-diethoxyethane, and tetrahydrofuran, and water, acetone, and ethanol are particularly preferred. The amount of the solvent (d) may be 1 to 300 parts by weight, for example, 50 to 300 parts by weight, or 100 to 250 parts by weight, based on the total amount of all polymerizable monomers.

<Other ingredients>
In addition, the dental photocurable composition of the present invention may contain components other than the above components (a) to (d) as long as the effects of the present invention are not impaired. For example, components such as excipients typified by fumed silica, benzophenone-based and benzotriazole-based ultraviolet absorbers, polymerization inhibitors such as hydroquinone, hydroquinone monomethyl ether, and 2,5-ditertiarybutyl-4-methylphenol, chain transfer agents such as mercaptan compounds such as α-alkylstyrene compounds, n-butyl mercaptan, and n-octyl mercaptan, terpenoid compounds such as limonene, myrcene, α-terpinene, β-terpinene, γ-terpinene, terpinolene, β-pinene, and α-pinene, metal capture agents such as aminocarboxylic acid-based chelating agents and phosphonic acid-based chelating agents, discoloration inhibitors, antibacterial agents, coloring pigments, water and solvents that can be mixed with water in any ratio, and other conventionally known additives can be added as necessary.

The method for preparing the dental photocurable composition of the present invention is not particularly limited. Typical methods for producing dental photocurable compositions include a method in which a binder resin is prepared by mixing (a) a polymerizable monomer and (c) a photopolymerization initiator in advance, and then this binder resin is kneaded with (b) a filler and air bubbles are removed under vacuum to prepare a uniform paste-like composition, and a method in which (a) a polymerizable monomer, (c) a photopolymerization initiator, and (d) a solvent are mixed to prepare a homogeneous liquid composition. In the present invention, the composition can be produced without any problems using the above-mentioned production method.

In the dental field, dental photocurable compositions are used for intraoral treatment and have potential for industrial applications, as they are applied to dental adhesives, dental composite resins, dental abutment construction materials, dental resin cements, dental surface coating materials, dental pit and fissure sealants, dental manicure materials, etc.

The following describes specific examples of the present invention, but the present invention is not limited to these examples.

The materials used in the examples and comparative examples and their abbreviations are shown below.
[(a) Polymerizable Monomer]
Bis-GMA: 2,2-bis[4-(3-methacryloyloxy-2-hydroxypropoxy)phenyl]propane 2.6E: 2,2-bis(4-(meth)acryloyloxypolyethoxyphenyl)propane with an average added mole number of ethoxy groups of 2.6 UDMA: N,N-(2,2,4-trimethylhexamethylene)bis[2-(aminocarboxy)ethanol]methacrylate TEGDMA: Triethylene glycol dimethacrylate GDMA: Glycerol dimethacrylate 2-HEMA: 2-hydroxyethyl methacrylate MDP: 10-methacryloyloxydecyl dihydrogen phosphate 6-MHPA: 6-methacryloxyhexyl phosphonoacetate 4-MET: 4-methacryloxyethyl trimellitic acid

[(c) Polymerization initiator]
(c-1) Photosensitizer CQ: α-camphorquinone

(c-2) Polymerization accelerator Aromatic tertiary amine compound DMBE: N,N-dimethylaminobenzoic acid ethyl Aliphatic tertiary amine compound DMAEMA: N,N-dimethylaminoethyl methacrylate Organometallic compound SnL: Dioctyl-tin-dilaurate

(c-3) Diaryliodonium Salt IPIFP: 4-isopropylphenyl(p-tolyl)iodonium tris(pentafluoroethyl)trifluorophosphate

tBIFP: bis(4-tert-butylphenyl)iodonium tris(pentafluoropropyl)trifluorophosphate

・DPIHP: Diphenyliodonium hexafluorophosphate

(d) Solvent: Water, Acetone

[(b) Filler]
The manufacturing method of each filler used in the preparation of the dental photocurable composition is shown below.

100.0 g of zirconium silicate filler (average particle size 2.2 μm: zirconia 90 wt%, silica 10 wt%) was mixed with 50.0 g of water, 35.0 g of ethanol, and 3.0 g of 3-methacryloyloxypropyltrimethoxysilane as a silane coupling agent, stirred at room temperature for 2 hours, to obtain a silane coupling treatment liquid, which was then added and stirred for 30 minutes. After that, heat treatment was performed at 140°C for 15 hours to obtain Filler 1.

100.0 g of zirconium silicate filler (average particle size 0.8 μm: zirconia 85 wt%, silica 15 wt%) was mixed with 50.0 g of water, 35.0 g of ethanol, and 5.0 g of 3-methacryloyloxypropyltrimethoxysilane as a silane coupling agent, stirred at room temperature for 2 hours, and the resulting silane coupling treatment liquid was added and mixed for 30 minutes. After that, heat treatment was performed at 140°C for 15 hours to obtain filler 2.

Chemical polymerization initiator Thiourea derivatives BTU: N-benzoylthiourea Organic peroxides with hydroperoxide groups CHP: Cumene hydroperoxide

UV absorber ・BT: 2-(2-hydroxy-5-methylphenyl)benzotriazole polymerization inhibitor ・BHT: 2,6-di-t-butyl-4-methylphenol

<Method of producing dental photocurable composition (dental filling composite resin)>
The polymerizable monomer (a), polymerization initiator (c), and other ingredients shown in Table 1 were mixed for 24 hours at 100 rpm using a VMRC-5 mix rotor to obtain a binder resin in which each ingredient was uniformly dissolved. The binder resin and filler (b) were then added to a kneader, uniformly stirred, and degassed under vacuum to prepare dental photocurable compositions of Examples 1 to 12 and Comparative Examples 1 and 2.

<Method for producing dental photocurable composition (dental resin cement)>
The polymerizable monomer (a), polymerization initiator (c), and other materials shown in Table 2 were mixed for 24 hours at 100 rpm using a VMRC-5 mix rotor to obtain a binder resin in which each material was uniformly dissolved. The binder resin and filler (b) were then placed in a kneader and uniformly stirred, and then degassed under vacuum to obtain pastes 1 and 2. These were then filled into a Mixpack double syringe (5 mL) to prepare the dental photocurable compositions of Examples 13 to 22 and Comparative Examples 3 and 4.

<Production method of dental photocurable composition>
The polymerizable monomer (a), polymerization initiator (c), and other components shown in Table 3 were mixed for 24 hours at 100 rpm using a mix rotor VMRC-5, and the dental photocurable compositions of Examples 23 to 28 and Comparative Examples 5 to 8 were prepared in which each material was uniformly dissolved.

<Method for producing dental photocurable composition (dental adhesive)>
(a) Polymerizable monomer, (c) photopolymerization initiator, and (d) solvent shown in Table 4 were mixed using a Turbula Mixer T2F (Shinmaru Enterprises, Inc.) to prepare homogeneous liquid dental photocurable compositions, which were then filled into light-shielding plastic containers to prepare the dental photocurable compositions of Examples 29 to 36 and Comparative Examples 9 to 10.

The test methods used in the examples and comparative examples are as follows. The dental filling composite resin and dental resin composition were directly collected, and the dental resin cement was prepared by mixing pastes 1 and 2 using a mixing tip manufactured by Mixpack.

(1) Bending strength The prepared dental photocurable composition was filled into a stainless steel mold, cover glass was placed on both sides, and the composition was pressed with a glass plate. Then, light was irradiated for 10 seconds at 5 locations using a photopolymerization irradiator (Blue Shot: manufactured by Matsukaze) to cure the composition. After curing, the cured product was removed from the mold, and the back side was irradiated with light in the same manner, to obtain a test specimen (25 x 2 x 2 mm: rectangular parallelepiped type). The test specimen was immersed in water at 37°C for 24 hours, and then a bending test was performed.
The bending test was carried out using an Instron universal testing machine (manufactured by Instron Corporation) with a support distance of 20 mm and a crosshead speed of 1 mm/min.

(2) Ambient light stability Using an illuminometer, adjust the height of a dental lamp (Luna-Vue S, Morita Seisakusho) so that light with an illuminance of 8000±1000 lx hits the sample mounting area. After placing a slide glass (26×16 mm, thickness 2 mm) on a glass mixing board with non-glossy black paper laid on it, about 30 mg of sample was taken on it. After exposing the sample to light for 60±5 seconds on the sample mounting area, the sample was removed from the sample mounting area, and another slide glass was immediately pressed against the sample to form a thin layer. If the state of the sample at this time was not physically uniform, it was judged that curing had started, and the time until curing was evaluated in 5-second increments. The longer this time, the better the ambient light stability.

(3) Discoloration of the cured product a) Dental photocurable compositions (excluding dental adhesives)
The dental photocurable compositions thus prepared were filled into stainless steel molds (15φ×1 mm: disk-shaped), and then a cover glass was placed on top and pressed with a glass plate. The cover glass was irradiated with light for 1 minute using a photopolymerization irradiator (Grip Light II: Matsukaze Co., Ltd.) to cure the composition. The cured product was removed from the mold, the cover glass was removed, and the color tone of the test specimen was measured.
The color measurement was performed by placing the test specimen on a background of a standard white plate (D65/10°X=81.07, Y=86.15, Z=93.38) and using a spectrophotometer (manufactured by BYK-Chemie) under a certain set of conditions (light source: C, viewing angle: 2°, measurement area: 11 mm). After that, the test specimen was exposed to light for 24 hours using a xenon lamp light exposure tester (Suntest CPS+), and the color tone of the test specimen was measured again, and the difference in color change was expressed as ΔE calculated by the following formula.
ΔE={(ΔL*) ² + (Δa*) ² + (Δb*) ² } ^1/2
ΔL*=L1*-L2*
Δa*=a1*-a2*
Δb*=b1*-b2*
Here, L1* is the lightness index before light exposure, L2* is the lightness index after light exposure, a1* and b1* are color quality indices before light exposure, and a2* and b2* are color quality indices after light exposure.
b) Dental photocurable composition (dental adhesive)
A polyethylene frame of 50 μm in thickness is fixed on a glass plate, the dental photocurable composition prepared is applied in the frame, and the operation of air drying is repeated until the liquid surface does not move. When the thickness reaches 50 μm or more, the glass plate is pressed and cured by irradiating light for 1 minute using a photopolymerization irradiator (Grip Light II: manufactured by Matsukaze). After removing the cured product from the frame, the cover glass is removed, and the color tone of this test specimen is measured. The color measurement is performed by placing the test specimen on the background of a standard white plate (D65/10°X=81.07, Y=86.15, Z=93.38) and using a spectrophotometer (manufactured by BYK-Chemie) under a certain predetermined condition (light source: C, viewing angle: 2°, measurement area: 11 mm). After that, the test specimen is immersed in water at 37°C for 2 months, and the color tone of the test specimen is measured again, and the difference in color change is expressed as ΔE calculated by the following formula.
ΔE={(ΔL*) ² + (Δa*) ² + (Δb*) ² } ^1/2
ΔL*=L1*-L2*
Δa*=a1*-a2*
Δb*=b1*-b2*
Here, L1* is the lightness index before immersion, L2* is the lightness index after immersion, a1* and b1* are color quality indices before immersion, and a2* and b2* are color quality indices after immersion.

(4) Evaluation of storage stability The prepared dental photocurable composition was stored in a thermostatic chamber set at 50°C under shielding, and after 90 days, (3) the same test for discoloration of the cured product was performed to check for precipitation of aryl iodonium salt. The storage stability was evaluated based on the change over time between the initial value and the value after 90 days at 50°C. Regarding precipitation, the paste was discharged from the syringe and the presence or absence of precipitation was confirmed. Those with no precipitation at all were rated A, those with slight precipitation were rated B, and those with obvious precipitation were rated C. In addition, dental photocurable compositions without aryl iodonium salt were prepared as reference samples for each composition, and it was confirmed that there was no precipitation in any of them.

(5) Evaluation of Durable Adhesive Strength The crown of an extracted mandibular permanent central incisor was cut and the bovine tooth was embedded in small pieces of epoxy resin. The embedded bovine tooth was exposed to the dentin with #600 waterproof abrasive paper under water injection, washed with water and dried.
A double-sided tape with a hole of 4 mm in diameter is applied to the exposed dentin to define the adhesive surface. A plastic mold (inner diameter 4 mm, height 2 mm or 4 mm) is fixed to the defined surface, and a dental hardening composition is applied to the adhesive surface, and the composition is cured by irradiating light for 20 seconds using a photopolymerization irradiator (Grip Light II: manufactured by Matsufu). Then, dental composite resin "Beauty Fill Flow Plus" (Matsufu Co., Ltd.) is filled into the mold, and the composition is cured by irradiating light for 20 seconds again. The plastic mold is removed to prepare an adhesive test specimen. This adhesive test specimen is immersed in distilled water at 37°C for 24 hours, and then a dentin adhesion test is performed using an Instron universal testing machine (Instron 5567, manufactured by Instron Co., Ltd.) at a crosshead speed of 1 mm/min to measure the initial adhesive strength.
In addition, adhesion test specimens were prepared and immersed in distilled water at 37°C for 24 hours, after which they were subjected to 10,000 thermal cycles (alternate immersion at 55°C for 30 seconds and 5°C for 30 seconds) to perform a dentin adhesion test, and the results were recorded as durable adhesive strength.

[Examples 1 to 12]
The dental photocurable compositions of Examples 1 to 12 exhibited high bending strength, excellent environmental light stability, and high discoloration resistance. In addition, even after 90 days at 50°C, there was almost no decrease in discoloration resistance or precipitation, and the compositions had excellent storage stability.

[Comparative Examples 1 to 2]
The dental photocurable composition of Comparative Example 1 had low environmental light stability, and was significantly discolored, and precipitation of aryl iodonium salt was observed. The dental photocurable composition of Comparative Example 2 was confirmed to have low bending strength and significant discoloration.

The evaluation results for the dental photocurable compositions (dental resin cements) of the Examples and Comparative Examples are shown in Table 5.

[Examples 13 to 22]
The dental photocurable compositions of Examples 13 to 22 exhibited high bending strength, excellent environmental light stability, and high discoloration resistance. In addition, even after 90 days at 50°C, there was almost no decrease in discoloration resistance or precipitation, and the compositions had excellent storage stability.

Comparative Examples 3 to 4
The dental photocurable composition of Comparative Example 3 showed significant discoloration and precipitation of aryl iodonium salt was observed. It was confirmed that the dental photocurable composition of Comparative Example 4 had low bending strength and significant discoloration.

The evaluation results for the dental photocurable compositions of the Examples and Comparative Examples are shown in Table 6.

[Examples 23 to 28]
The dental photocurable compositions of Examples 23 to 28 exhibited high bending strength and excellent stability to environmental light, and no precipitation of the aryliodonium salt was observed even after 90 days at 50° C., demonstrating excellent storage stability.

Comparative Examples 5 to 8
The dental photocurable compositions of Comparative Examples 5 and 6 had low bending strength and low environmental light stability, and precipitation of aryl iodonium salts was observed after 90 days at 50° C. The dental photocurable compositions of Comparative Examples 7 and 8 had low bending strength, and Comparative Example 8 was also confirmed to have low environmental light stability.

In Table 7, "-" indicates that no aryliodonium salt is included.

[Examples 29 to 36]
The dental photocurable compositions of Examples 29 to 36 had high adhesive strength, particularly high durable adhesion, and no precipitation of aryliodonium salt was observed even after 90 days at 50°C. Discoloration after immersion in water was extremely low, indicating excellent storage stability.

[Comparative Examples 9 and 10]
The dental photocurable compositions of Comparative Examples 9 and 10 had low adhesive strength and color stability, and precipitation of the aryl iodonium salt was observed after 90 days at 50° C. These results demonstrated the effectiveness of the aryl iodonium salt of a specific structure.

In the above examples, a dental filling composite resin, a dental resin cement, and a dental adhesive were described, but the present invention can be used with other dental photocurable compositions without any restrictions.

Claims (5)

( a) a polymerizable monomer ; and
(c-1) a photosensitizer,
(c-2) a polymerization accelerator, and
(c-3) Formula (1):

(wherein R1 represents an aryl group having 6 to 30 carbon atoms which may have at least one substituent and is bonded to I, R2 represents an alkyl group in which some of the hydrogen atoms are substituted with fluorine atoms, and b represents the number of alkyl groups and is an integer of 1 to 5).
(c) a photopolymerization initiator comprising
Including,
The (a) polymerizable monomer is a (meth)acrylate monomer having an acryloyl group and/or a methacryloyl group or a (meth)acryloyl polymerizable monomer.
Dental photocurable composition. The dental light-curable composition of claim 1 , further comprising: (b) a filler. (c) a photopolymerization initiator,
(a) relative to 100 parts by mass of the polymerizable monomer,
(c-1) photosensitizer: 0.1 to 5 parts by mass,
(c-2) a polymerization accelerator: 0.01 to 10 parts by mass, and (c-3) an aryl iodonium salt represented by formula (1): 0.01 to 10 parts by mass
The dental photocurable composition according to claim 1 or 2 , comprising : (a) relative to 100 parts by mass of the polymerizable monomer,
4. The dental photocurable composition according to claim 3 , wherein the filler (b) is contained in an amount of 10 to 1,900 parts by weight. 5. The dental photocurable composition according to any one of claims 1 to 4 , which is a dental adhesive, a dental composite resin, a dental abutment construction material, a dental resin cement, a dental surface coating material, a dental pit and fissure sealant, and/or a dental manicure material.