Dental resin composition

Abstract

To provide a dental resin composition that exhibits excellent curability and low viscosity, resulting in superior formability when fabricated by stereolithography (liquid bath stereolithography), and also has excellent solubility, making it easy to clean, and whose cured product has excellent strength and repeated fatigue properties. Furthermore, to provide a dental resin composition that is particularly suitable for dental mouthpieces and denture base materials manufactured by stereolithography. [Solution] A dental resin composition containing a monofunctional urethane-(meth)acrylic polymerizable compound (A) and a photopolymerization initiator (B).

Description

Technical Field

[0001] The present invention relates to a dental resin composition. More specifically, the present invention is excellent in curability and has a low viscosity, so it is excellent in formability when shaped by stereolithography (tank lithography), and is excellent in solubility so it is easy to clean. Its cured product is excellent in strength and repeated fatigue characteristics. In particular, it is suitable for dental occlusion splints and denture base materials produced by stereolithography.

Background Art

[0002] A number of proposals have been made regarding a method for manufacturing a three-dimensional object, so-called optical stereolithography, in which a necessary amount of controlled light energy is supplied to a liquid photocurable resin to cure it in a thin layer, and then a liquid photocurable resin is further supplied thereon, followed by irradiating with light under control to cure and laminate in a thin layer, and repeating this process.

[0003] As a typical method for optically manufacturing a three-dimensional object, a computer-controlled ultraviolet laser is selectively irradiated onto the liquid surface of a liquid photocurable resin composition placed in a container so as to obtain a desired pattern, and cured to a predetermined thickness to form a cured layer. Next, a single layer of the liquid photocurable resin composition is supplied onto the cured layer, and similarly irradiated with an ultraviolet laser and cured in the same manner as above to form a continuous cured layer. A method called tank lithography, which repeats this lamination operation to manufacture a three-dimensional object of the final shape, is generally adopted. In the case of this method, even if the shape of the object to be shaped is quite complicated, it is possible to easily and relatively quickly manufacture the target three-dimensional object with high accuracy, and thus it has attracted great attention in recent years.

[0004] And the applications of three-dimensional objects obtained by the stereolithography method have been developed from mere concept models to test models, prototypes, and final products. Especially in the field of dental materials, dental occlusion splints, denture bases, and mouthpiece-shaped sleep disorder treatment materials such as bruxism prevention are expected to apply the stereolithography method because the shapes are different for each patient and the shapes are complicated.

[0005] Dental occlusal splints are devices worn to correct tooth alignment and jaw position, similar to orthodontic mouthpieces or aligners; devices worn to reduce tooth wear caused by teeth grinding; and, as mouthguards, devices worn in the mouth during contact sports to reduce injuries caused by strong external forces applied to the teeth and jawbone during competition, thereby protecting the maxillofacial system and brain. In recent years, their use in orthodontics has rapidly expanded due to their aesthetic appeal and the fact that they can be removed when desired.

[0006] Denture base material is the material used for the gum portion when dentures are fitted due to tooth loss. In recent years, the demand for dentures has increased rapidly due to the growing elderly population.

[0007] Dental occlusal splints and the denture base materials both require strength and repeated fatigue resistance. If strength is compromised, the splint will not serve its purpose. Furthermore, if flexural fatigue resistance is compromised, the splint will become prone to fracture due to repeated deformation during occlusion and wear, necessitating frequent remanufacturing. Generally, improving strength tends to make the material harder and more brittle, making it extremely difficult to achieve both strength and repeated fatigue resistance simultaneously.

[0008] Against this backdrop, as a technology that offers excellent strength and fracture properties in cured products and enables optical three-dimensional fabrication, for example, Patent Document 1 proposes a photopolymerization resin composition made of a specific urethane oligomer that has excellent formability, strength, and toughness, and Patent Document 2 proposes a photopolymerization resin composition made of a urethane oligomer and a nitrogen-containing ring monomer that also has excellent formability, strength, and toughness. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] International Publication No. 2020 / 071552 [Patent Document 2] International Publication No. 2020 / 129736 [Overview of the project] [Problems that the invention aims to solve]

[0010] However, it has become clear that while the toughness described in Patent Documents 1 and 2 can serve as an indicator of fracture characteristics for a single deformation, it does not correlate with repeated deformation, and these technologies have problems with repeated fatigue characteristics. Furthermore, in stereolithography, it is necessary to wash away any excess photopolymerizable resin composition adhering to the fabricated object. However, urethane-based oligomers have low affinity for isopropyl alcohol (IPA) and other cleaning solvents, and their high viscosity makes them even more difficult to dissolve. As a result, the stereolithography resin compositions using urethane-based oligomers described in Patent Documents 1 and 2 have problems with cleanability. Therefore, the present invention aims to provide a dental resin composition that exhibits excellent curability and low viscosity, resulting in excellent formability when fabricated by stereolithography (liquid bath stereolithography), and also has excellent solubility, making it easy to clean, and whose cured product has excellent strength and repeated fatigue properties. Furthermore, the present invention aims to provide a dental resin composition that is particularly suitable for dental mouthpieces and denture base materials manufactured by stereolithography. [Means for solving the problem]

[0011] In other words, the present invention relates to the following invention. [1] Dental resin composition containing a monofunctional urethane-(meth)acrylic polymerizable compound (A) and a photopolymerization initiator (B); [2] The dental resin composition according to [1] further comprising a polyfunctional (meth)acrylic polymerizable compound (C) and / or a monofunctional (meth)acrylic polymerizable compound (D) that does not contain a urethane bond; [3] The dental resin composition according to [1] or [2], wherein the molecular weight of the monofunctional urethane-(meth)acrylic polymerizable compound (A) is 1000 or less; [4] The dental resin composition according to any one of [1] to [3], wherein the polyfunctional (meth)acrylic polymerizable compound (C) contains a polyfunctional (meth)acrylic polymerizable compound (C)-I containing a urethane bond; [5] A dental resin composition according to [4] containing a monofunctional (meth)acrylic polymerizable compound (D) that does not contain urethane bonds; A dental resin composition described in any of [6][1] to [5] is a dental resin composition for use in stereolithography; A dental occlusal splint comprising a cured product of any of the dental resin compositions described in [7][1] to [6]. A denture base material comprising a cured product of any of the dental resin compositions described in [8][1] to [6]. A method for manufacturing a three-dimensional object by optical stereolithography using a dental resin composition described in any of [9][1] to [6]. [Effects of the Invention]

[0012] The dental resin composition of the present invention exhibits excellent curability and low viscosity, resulting in superior formability when fabricated by stereolithography (liquid bath stereolithography). Furthermore, its excellent solubility makes it easy to clean, and the cured product has excellent strength and repeated fatigue properties (resistance to repeated deformation (e.g., bending)). For these reasons, the dental resin composition of the present invention is suitable for dental occlusal splints and denture base materials manufactured by stereolithography. [Modes for carrying out the invention]

[0013] The present invention will be described in detail below using embodiments. In this specification, the upper and lower limits of numerical ranges (content of each component, values ​​calculated from each component, and each physical property, etc.) can be combined as appropriate. For example, in this specification, the lower and upper limits of numerical ranges described in steps can be combined independently. For example, from the description "preferably 0.2 to 8.0 mass%, more preferably 0.5 to 5.0 mass%" for the same item, the "preferred lower limit (0.2 mass%)" and the "more preferred upper limit (5.0 mass%)" can be combined to get "0.2 to 5.0 mass%" or 0.5 to 8.0 mass%. Furthermore, regarding the numerical range, for example, based on the statement "more preferably 12 to 28 mass%, and even more preferably 12.5 to 25 mass%,", the upper limit may not be specifically specified, and only the lower limit may be specified as "12 mass% or more" or "12.5 mass% or more". Similarly, the lower limit may not be specifically specified, and only the upper limit may be specified as "28 mass% or less" or "25 mass% or less". Unless otherwise specified, when a numerical range is simply written as "30~70", it represents the range from 30 to 70. Furthermore, for example, if the numerical range is "25% or more and 75% or less", the boundary of the numerical range can be selected from "greater than 25%", "25% or more", "75% or less", or "less than 75%". Similarly, for example, from the statements "more preferably 0.05 parts by mass or more, and even more preferably 0.1 parts by mass or more" and "more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less" for the same item, it is possible to combine the "more preferred lower limit (0.05 parts by mass or more)" and the "even more preferred upper limit (10 parts by mass or less)" to get "0.05 parts by mass or more and 10 parts by mass or less". Also, similarly, the lower limit can be specified as "0.05 parts by mass or more" or "0.1 parts by mass or more", and similarly, the upper limit can be specified as "15 parts by mass or less" or "10 parts by mass or less". The numerical ranges mentioned above are merely illustrative examples using mass%, and the same applies to molecular weight, flexural strength, flexural modulus, etc. The present invention includes embodiments in which all or part of the embodiments described in this specification are variously combined within the scope of the technical idea of the present invention as long as the effects of the present invention are achieved.

[0014] In this specification, the "polymerizable compound" is used in the sense of a polymerizable compound that is polymerized by a photoinitiator (B) described later. In addition, in this specification, the notation "(meth)acryl" is used to include both "methacryl" and "acryl". The same applies to notations similar to this such as "(meth)acrylate", "(meth)acrylic acid ester", "(meth)acrylamide", "(meth)acryloyloxy", and the like. In addition, in this specification, the "(meth)acrylic polymerizable compound" is used to include both a polymerizable compound having a "(meth)acryloxy group" as a polymerizable group and a polymerizable compound having a "(meth)acrylamide group" as a polymerizable group. In addition, in this specification, "polyfunctional" means that the number of polymerizable groups (preferably, (meth)acryl groups) exceeds 1. In addition, in this specification, "monofunctional" means having one polymerizable group (preferably, (meth)acryl group). In addition, in this specification, the "molecular weight" is a single value calculated from the atomic weight when it does not include an oligomer or polymer structure, and when it includes an oligomer or polymer structure, it is the weight average molecular weight unless otherwise specified, and means the weight average molecular weight in terms of polystyrene determined by gel permeation chromatography (GPC).

[0015] The dental resin composition of the present invention contains a monofunctional urethanized (meth)acrylic polymerizable compound (A) and a photoinitiator (B).

[0016] [Monofunctional urethanized (meth)acrylic polymerizable compound (A)] The monofunctional urethanized (meth)acrylic polymerizable compound (A) is used in the dental resin composition of the present invention to impart curability when combined with a photoinitiator (B) in the dental resin composition, and to impart repeated fatigue characteristics to the cured product. The monofunctional urethanized (meth)acrylic polymerizable compound (A) contains a urethane bond at one end of the molecule. Since the dental resin composition of the present invention is excellent in curability and has a low viscosity, it is excellent in formability when shaped by stereolithography (tank stereolithography), and is excellent in solubility and thus easy to clean. The reason why its cured product is excellent in strength and repeated fatigue characteristics is not clear, but it is推测 as follows. The monofunctional urethanized (meth)acrylic polymerizable compound has a urethane bond only at one end, not at both ends of the molecule. Therefore, it is推测 that an intermolecular bridging structure via hydrogen bonding of the urethane bond is difficult to form, so the viscosity is not likely to increase and the detergency can be kept good. Also, since a (meth)acryloyl group is present at one end of the molecule, a crosslinked structure is not formed after curing. Therefore, a structure that is too rigid is not formed and flexibility is maintained, so it is推测 that it is excellent in repeated fatigue characteristics (especially repeated bending fatigue characteristics). The number of urethane bonds in the monofunctional urethanized (meth)acrylic polymerizable compound (A) is not particularly limited, but from the point of view of making it difficult to form an intermolecular bridging structure via hydrogen bonding of the urethane bond, it is preferably 1.

[0017] The monofunctional urethanized (meth)acrylic polymerizable compound (A) preferably has a molecular weight of 1000 or less, more preferably 750 or less, and even more preferably 500 or less, from the points of view of easily reducing the viscosity of the dental resin composition and excellent detergency. Furthermore, monofunctional urethane-(meth)acrylic polymerizable compound (A) is preferably free of polar functional groups because it is easier to reduce the viscosity of dental resin compositions. Examples of polar functional groups include acidic groups such as hydroxyl groups, carboxyl groups, sulfonic acid groups, sulfinic acid groups, and phosphate groups, as well as halides, primary and secondary amino groups, and their salts. The monofunctional urethane-(meth)acrylic polymerizable compound (A) may be used alone or in combination of two or more types.

[0018] Monofunctional urethane-modified (meth)acrylic polymerizable compound (A) can be easily synthesized by an addition reaction between a (meth)acrylic compound containing a hydroxyl group (-OH) and a monofunctional isocyanate compound having one isocyanate group (-NCO). Alternatively, it can also be easily synthesized by an addition reaction between a compound containing one hydroxyl group (-OH) and a (meth)acrylic compound having one isocyanate group (-NCO). Furthermore, it can be synthesized by an addition reaction between an organic compound containing a hydroxyl group but not a (meth)acrylic group and a polyfunctional isocyanate compound containing multiple isocyanate groups, adjusting the mixing ratio of the organic compound containing a hydroxyl group but not a (meth)acrylic group and the polyfunctional isocyanate compound so that one isocyanate group remains in the polyfunctional isocyanate compound, and then further adding it to a (meth)acrylic compound containing a hydroxyl group (-OH). From the viewpoint of purity and viscosity of the monofunctional (meth)acrylic polymerizable compound (A), a method of reacting with a monofunctional isocyanate compound having one isocyanate group (-NCO) is preferred, and from the viewpoint of the types of monofunctional (meth)acrylic polymerizable compounds (A) that can be synthesized, a method of reacting with a polyfunctional isocyanate compound is preferred. The aforementioned monofunctional isocyanate compound means a compound having one isocyanate group, and the aforementioned polyfunctional isocyanate compound means a compound having two or more isocyanate groups.

[0019] Examples of monofunctional isocyanate compounds having one isocyanate group include methyl isocyanate, ethyl isocyanate, propyl isocyanate, isopropyl isocyanate, allyl isocyanate, n-butyl isocyanate, tert-butyl isocyanate, 3-isocyanate pentane, cyclopentyl isocyanate, n-hexyl isocyanate, cyclohexyl isocyanate, cyclohexylmethyl isocyanate, n-octyl isocyanate, 2-octyl isocyanate, 2-ethylhexyl isocyanate, n-dodecyl isocyanate, n-hexadecyl isocyanate, n-octadecyl isocyanate, 2-chloroethyl isocyanate, 2-bromoethyl isocyanate, 3-chloropropyl isocyanate, methyl isocyanate formate, and chloroacetate. Examples include ethyl isocyanate, trichloroacetyl isocyanate, ethyl formate, ethyl isocyanate, ethyl 3-isocyanate propionate, phenyl isocyanate, tolyl isocyanate, dimethylphenyl isocyanate, tert-butylphenyl isocyanate, methoxyphenyl isocyanate, N,N-dimethylaminophenyl isocyanate, cyanophenyl isocyanate, acetylphenyl isocyanate, benzyl isocyanate, bromobenzyl isocyanate, phenethyl isocyanate, fluorobenzyl isocyanate, chlorobenzyl isocyanate, methoxybenzyl isocyanate, benzoyl isocyanate, naphthyl isocyanate, biphenylyl isocyanate, 1-adamantyl isocyanate, and furfuryl isocyanate.Among these, isopropyl isocyanate, n-butyl isocyanate, tert-butyl isocyanate, cyclopentyl isocyanate, n-hexyl isocyanate, cyclohexyl isocyanate, 2-octyl isocyanate, 2-ethylhexyl isocyanate, phenyl isocyanate, tolyl isocyanate, dimethylphenyl isocyanate, tert-butylphenyl isocyanate, methoxyphenyl isocyanate, N,N-dimethylaminophenyl Socyanates, benzyl isocyanates, phenethyl isocyanates, methoxybenzyl isocyanates, benzoyl isocyanates, 1-adamantyl isocyanates, and furfuryl isocyanates are more preferred, and tert-butyl isocyanates, n-hexyl isocyanates, cyclohexyl isocyanates, 2-ethylhexyl isocyanates, phenyl isocyanates, tert-butylphenyl isocyanates, methoxyphenyl isocyanates, benzyl isocyanates, 1-adamantyl isocyanates, and furfuryl isocyanates are even more preferred.

[0020] Examples of (meth)acrylic compounds having a hydroxyl group include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, glycerin mono(meth)acrylate, and 2-hydroxy-3-acryloyloxypropyl (meth)acrylate. Examples include hydroxy(meth)acrylate compounds such as 2,2-bis[4-(2-hydroxy-3-(meth)acryloyloxypropoxy)phenyl]propane, 1,2-bis[3-(meth)acryloyloxy-2-hydroxypropoxy]ethane, pentaerythritol tri(meth)acrylate, and dipentaerythritol tri or tetra(meth)acrylate; and hydroxy(meth)acrylamide compounds such as N-hydroxyethyl(meth)acrylamide and N,N-bis(2-hydroxyethyl)(meth)acrylamide. If the target monofunctional urethane-based (meth)acrylic polymerizable compound (A) is a (meth)acrylate compound, it can be produced by selecting a hydroxy(meth)acrylate compound.

[0021] Examples of (meth)acrylic compounds containing one isocyanate group include 2-isocyanate ethyl (meth)acrylate and 2-(2-methacryloyloxyethyl oxy)ethyl isocyanate lenses.

[0022] The addition reaction between a compound having an isocyanate group and a (meth)acrylic compound having a hydroxyl group can be carried out using known methods and conditions, and is not particularly limited; however, from the viewpoint of biological safety, methods that do not use organotin compounds as catalysts are preferred.

[0023] The content of monofunctional urethane-(meth)acrylic polymerizable compound (A) is preferably 5 to 100% by mass of 100% by mass of the total amount of polymerizable compounds. When combined with other components (preferably polyfunctional (meth)acrylic polymerizable compound (C) and / or monofunctional (meth)acrylic polymerizable compound (D) that does not contain urethane bonds), it is more preferably 10 to 80% by mass, even more preferably 15 to 60% by mass, and particularly preferably 20 to 50% by mass, as this can improve the curability, cleanability, strength of molded products, and repeated fatigue characteristics of the dental resin composition. Furthermore, in a preferred embodiment, the content of the monofunctional urethane (meth)acrylic polymerizable compound (A) is preferably 5 to 98% by mass of 100% by mass of the total amount of the dental resin composition, and is more preferably 10 to 80% by mass, even more preferably 15 to 60% by mass, and particularly preferably 18 to 50% by mass, from the viewpoint of superior strength and repeated fatigue characteristics of the cured product when combined with other components (preferably a polyfunctional (meth)acrylic polymerizable compound (C) and / or a monofunctional (meth)acrylic polymerizable compound (D) that does not contain urethane bonds).

[0024] [Photopolymerization initiator (B)] The photopolymerization initiator (B) used in the present invention can be selected from polymerization initiators used in general industry, and among them, photopolymerization initiators used in dental applications are preferred.

[0025] Examples of photopolymerization initiators (B) include (bis)acylphosphine oxides, thioxanthones or quaternary ammonium salts of thioxanthones, ketals, α-diketones, coumarins, anthraquinones, benzoin alkyl ether compounds, and α-aminoketone compounds. One type of photopolymerization initiator (B) may be used alone, or two or more types may be used in combination.

[0026] Among these photopolymerization initiators (B), it is preferable to use at least one selected from the group consisting of (bis)acylphosphine oxides and α-diketones. This results in a dental resin composition that exhibits excellent photocurability in the ultraviolet and visible light regions and shows sufficient photocurability regardless of whether a laser, halogen lamp, light-emitting diode (LED), or xenon lamp is used as the light source.

[0027] Among the (bis)acylphosphine oxides, examples of acylphosphine oxides include ammonium salts such as diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, bis(p-tolyl)(2,4,6-trimethylbenzoyl)phosphine oxide, 2,6-dimethoxybenzoyldiphenylphosphine oxide, 2,6-dichlorobenzoyldiphenylphosphine oxide, (2,4,6-trimethylbenzoyl)methoxyphenylphosphine oxide, (2,4,6-trimethylbenzoyl)ethoxyphenylphosphine oxide, 2,3,5,6-tetramethylbenzoyldiphenylphosphine oxide, benzoyldi(2,6-dimethylphenyl)phosphonate, 2,4,6-trimethylbenzoylphenylphosphine oxide sodium salt, 2,4,6-trimethylbenzoylphenylphosphine oxide potassium salt, and 2,4,6-trimethylbenzoyldiphenylphosphine oxide. Examples of bisacylphosphine oxides include bis(2,6-dichlorobenzoyl)phenylphosphine oxide, bis(2,6-dichlorobenzoyl)-2,5-dimethylphenylphosphine oxide, bis(2,6-dichlorobenzoyl)-4-propylphenylphosphine oxide, bis(2,6-dichlorobenzoyl)-1-naphthylphosphine oxide, bis(2,6-dimethoxybenzoyl)phenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,5-dimethylphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and bis(2,5,6-trimethylbenzoyl)-2,4,4-trimethylpentylphosphine oxide. Furthermore, compounds described in Japanese Patent Publication No. 2000-159621 can also be cited.

[0028] Among these (bis)acylphosphine oxides, it is particularly preferable to use 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(p-tolyl)(2,4,6-trimethylbenzoyl)phosphine oxide, (2,4,6-trimethylbenzoyl)ethoxyphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and 2,4,6-trimethylbenzoylphenylphosphine oxide sodium salt as photopolymerization initiators (B).

[0029] Examples of α-diketones include diacetyl, benzyl, camphorquinone, 2,3-pentadione, 2,3-octadione, 9,10-phenanthrenequinone, 4,4'-oxybenzyl, and acenaphthenequinone. Among these, camphorquinone is particularly preferred when using a light source in the visible light range.

[0030] The content of the photopolymerization initiator (B) in the dental resin composition of the present invention is not particularly limited, but from the viewpoint of the curability of the resulting dental resin composition, the amount of photopolymerization initiator (B) is preferably 0.01 to 20 parts by mass per 100 parts by mass of the total amount of polymerizable compound. If the content of photopolymerization initiator (B) is less than 0.01 parts by mass, polymerization may not proceed sufficiently, and molded articles may not be obtained. The content of photopolymerization initiator (B) is more preferably 0.05 parts by mass or more, even more preferably 0.1 parts by mass or more, and particularly preferably 0.5 parts by mass or more, per 100 parts by mass of the total amount. On the other hand, if the content of photopolymerization initiator (B) exceeds 20 parts by mass, if the solubility of the polymerization initiator itself is low, precipitation from the dental resin composition may occur. The content of photopolymerization initiator (B) is more preferably 15 parts by mass or less, even more preferably 10 parts by mass or less, and particularly preferably 5.0 parts by mass or less, per 100 parts by mass of the total amount.

[0031] [Polyfunctional (meth)acrylic polymerizable compounds (C)] The dental resin composition of the present invention may contain a polyfunctional (meth)acrylic polymerizable compound (C). In the dental resin composition of the present invention, the polyfunctional (meth)acrylic polymerizable compound (C) is used to impart curability to the dental resin composition and to impart strength to the cured product. By combining a polyfunctional (meth)acrylic polymerizable compound (C) with a monofunctional urethane-based (meth)acrylic polymerizable compound (A), curing properties are improved, and moldability and the strength of the cured product can be further enhanced. One preferred embodiment is a dental resin composition containing a monofunctional urethane-(meth)acrylic polymerizable compound (A), a photopolymerization initiator (B), and a polyfunctional (meth)acrylic polymerizable compound (C). In this embodiment, the monofunctional (meth)acrylic polymerizable compound (D) that does not contain urethane bonds may be omitted. In the preferred embodiments described above, the types and contents of the monofunctional urethane-(meth)acrylic polymerizable compound (A), the photopolymerization initiator (B), and the polyfunctional (meth)acrylic polymerizable compound (C), as well as fillers, stabilizers, additives, etc., as needed, can be changed according to the specifications.

[0032] Examples of polyfunctional (meth)acrylic polymerizable compounds (C) include polyfunctional (meth)acrylic polymerizable compound (C)-I containing urethane bonds (hereinafter also simply referred to as "polyfunctional (meth)acrylic polymerizable compound (C)-I") and polyfunctional (meth)acrylic polymerizable compound (C)-II not containing urethane bonds (hereinafter also simply referred to as "polyfunctional (meth)acrylic polymerizable compound (C)-II"). However, from the viewpoint of superior repeated fatigue characteristics of the molded product, it is preferable to include polyfunctional (meth)acrylic polymerizable compound (C)-I.

[0033] Polyfunctional (meth)acrylic compounds (C)-I are broadly classified into polyfunctional (meth)acrylic compounds (C)-I that do not contain polymer structures and polyfunctional (meth)acrylic compounds (C)-I that contain polymer structures. The amounts of these compounds used are not particularly limited and can be used selectively to adjust the physical properties such as the strength and repeated fatigue characteristics of the cured product of dental resin compositions.

[0034] A polyfunctional (meth)acrylic polymerizable compound (C)-I that does not contain a polymer structure can be easily synthesized, for example, by adding a compound having an isocyanate group containing an alkylene or phenylene skeleton to a (meth)acrylic compound having a hydroxyl group (-OH). Examples of compounds having an isocyanate group and (meth)acrylic compounds having a hydroxyl group (-OH) include those similar to those exemplified in the production of the monofunctional urethane-based (meth)acrylic polymerizable compound (A) described above. The addition reaction can be carried out using known methods and conditions, and is not particularly limited.

[0035] Examples of polyfunctional (meth)acrylic polymerizable compounds (C)-I that do not contain a polymer structure include 2,2,4-trimethylhexamethylenebis(2-carbamoyloxyethyl)dimethacrylate (commonly known as UDMA), 2,4-trylenebis(2-carbamoyloxyethyl)di(meth)acrylate, N,N-(2,2,4-trimethylhexamethylene)bis[2-(aminocarboxy)propane-1,3-diol]tetra(meth)acrylate, bishydroxyethyl methacrylate-isophorone diurethane, and polyfunctional urethane-modified (meth)acrylate of 2,4-trylenebis(2-carbamoyloxyethyl)dimethacrylate. These may be used individually or in combination of two or more. Among these, from the viewpoint of the strength of the molded object, 2,2,4-trimethylhexamethylenebis(2-carbamoyloxyethyl)dimethacrylate and N,N-(2,2,4-trimethylhexamethylene)bis[2-(aminocarboxy)propane-1,3-diol]tetra(meth)acrylate are preferred, with 2,2,4-trimethylhexamethylenebis(2-carbamoyloxyethyl)dimethacrylate being preferred.

[0036] Polyfunctional (meth)acrylic polymerizable compounds (C)-I containing polymer structures can be easily synthesized by adding a polyol having a polymer backbone, such as polyester, polycarbonate, polyurethane, polyether, polydiene, and hydrogenated polydiene, to a compound having an isocyanate group (-NCO) and a (meth)acrylic compound having a hydroxyl group (-OH). Alternatively, they can also be easily synthesized by adding a lactone or alkylene oxide to a (meth)acrylic compound having a hydroxyl group via a ring-opening addition reaction, and then adding the resulting compound having a hydroxyl group at one end to a compound having an isocyanate group.

[0037] The polyfunctional (meth)acrylic polymerizable compound (C)-I containing a polymer structure is preferably a (meth)acrylate containing at least one structure selected from the group consisting of polyester, polycarbonate, polyurethane, polyether, polyconjugated diene, and hydrogenated polyconjugated diene in one molecule.

[0038] In the above structure, for example, the polyester can be a copolymer of a dicarboxylic acid (e.g., aromatic dicarboxylic acids such as phthalic acid and isophthalic acid; unsaturated aliphatic dicarboxylic acid such as maleic acid) and an aliphatic diol having 2 to 18 carbon atoms, a copolymer of a dicarboxylic acid (e.g., saturated aliphatic dicarboxylic acid such as adipic acid and sebacic acid) and an aliphatic diol having 2 to 18 carbon atoms, a polymer of β-propiolactone, a polymer of γ-butyrolactone, a polymer of δ-valerolactone, a polymer of ε-caprolactone, and copolymers thereof. Preferably, the polymer is a copolymer of a dicarboxylic acid (preferably an aromatic dicarboxylic acid or an unsaturated aliphatic dicarboxylic acid) and an aliphatic diol having 2 to 12 carbon atoms, or a copolymer of a dicarboxylic acid (preferably a saturated aliphatic dicarboxylic acid) and an aliphatic glycol having 2 to 12 carbon atoms. Examples of polycarbonates include polycarbonates derived from aliphatic diols having 2 to 18 carbon atoms, polycarbonates derived from bisphenol A, and polycarbonates derived from aliphatic diols having 2 to 18 carbon atoms and bisphenol A. Polycarbonates derived from aliphatic diols having 2 to 12 carbon atoms, polycarbonates derived from bisphenol A, and polycarbonates derived from aliphatic diols having 2 to 12 carbon atoms and bisphenol A are preferred. Examples of polyurethanes include polymers of aliphatic diols having 2 to 18 carbon atoms and diisocyanates having 1 to 18 carbon atoms, with polymers of aliphatic diols having 2 to 12 carbon atoms and diisocyanates having 1 to 12 carbon atoms being preferred. Examples of polyethers include polyethylene glycol, polypropylene glycol, polybutylene glycol, and poly(1-methylbutylene glycol). Examples of polyconjugated dienes and hydrogenated polyconjugated dienes include 1,4-polybutadiene, 1,2-polybutadiene, polyisoprene, poly(butadiene-isoprene), poly(butadiene-styrene), poly(isoprene-styrene), polyfarnesene, and their hydrogenated derivatives. Among these, the polyester structure is preferred in terms of its excellent strength and repeated fatigue properties. Examples of the aforementioned polyconjugated diene include homopolymers or copolymers of conjugated diene monomers. Examples of the aforementioned conjugated diene monomers include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-betanediene, and 1,3-hexadiene. Examples of the hydrogenated polyconjugated dienes include hydrogenated polybutadiene, hydrogenated polyisoprene, and hydrogenated polyisobutylene. Among these, it is preferable to include at least one structure selected from the group consisting of polyester, polycarbonate, polyether, and hydrogenated polyconjugated diene as the polymer backbone, in terms of excellent strength and repeated fatigue characteristics, more preferable to include at least one structure selected from the group consisting of polyester and polycarbonate as the polymer backbone, and even more preferable to include at least one structure selected from the group consisting of polyester as the polymer backbone.

[0039] Examples of compounds having an isocyanate group and (meth)acrylic compounds having a hydroxyl group (-OH) include those similar to those exemplified in the production of the monofunctional urethane-based (meth)acrylic polymerizable compound (A) described above.

[0040] The addition reaction between a compound having an isocyanate group and a (meth)acrylic compound having a hydroxyl group can be carried out using known methods and conditions, and is not particularly limited.

[0041] The content of polyfunctional (meth)acrylic polymerizable compound (C)-I in polyfunctional (meth)acrylic polymerizable compound (C) is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 40% by mass or more, and most preferably 60% by mass or more, based on 100% by mass of the total amount of polyfunctional (meth)acrylic polymerizable compound (C), from the viewpoint of superior strength of the molded product. Alternatively, the content of polyfunctional (meth)acrylic polymerizable compound (C)-I in polyfunctional (meth)acrylic polymerizable compound (C) may be 100% by mass.

[0042] Examples of polyfunctional (meth)acrylic polymerizable compounds (C)-I include difunctional (meth)acrylic polymerizable compounds and trifunctional or more (meth)acrylic polymerizable compounds, but from the viewpoint of repeated fatigue characteristics of the molded product, difunctional (meth)acrylic polymerizable compounds are preferred.

[0043] Examples of polyfunctional (meth)acrylic polymerizable compounds (C)-II include bifunctional (meth)acrylic polymerizable compounds and trifunctional or more (meth)acrylic polymerizable compounds, but bifunctional (meth)acrylic polymerizable compounds are preferred from the viewpoint of repeated fatigue characteristics of the molded product.

[0044] Examples of polyfunctional (meth)acrylic polymerizable compounds (C)-II include 2,2-bis((meth)acryloyloxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxyethoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxydiethoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxypropoxyphenyl)propane, 2,2-bis[4-(2-hydroxy-3-methacryloyloxypropoxy)phenyl]propane (commonly known as "Bis-GMA"), 2,2-bis(4-(meth)acryloyloxytetraethoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxypentaethoxyphenyl) Xyphenyl)propane, 2-(4-(meth)acryloyloxydiethoxyphenyl)-2-(4-(meth)acryloyloxyethoxyphenyl)propane, 2-(4-(meth)acryloyloxydiethoxyphenyl)-2-(4-(meth)acryloyloxytriethoxyphenyl)propane, 2-(4-(meth)acryloyloxydipropoxyphenyl)-2-(4-(meth)acryloyloxytriethoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxyisopropoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxypolyethoxyphenyl)propane (for example, average number of moles of ethoxy groups added: 2.6) 1,4-Bis(2-(meth)acryloyloxyethyl)pyromellitate, glycerol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, 1,3 Examples include butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 2-ethyl-1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, 1,2-bis(3-methacryloyloxy-2-hydroxypropoxy)ethane, and tricyclodecanedimethanol di(meth)acrylate.

[0045] Examples of polymerizable compounds with three or more functionalities include trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, trimethylolmethane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, and 1,7-di(meth)acryloyloxy-2,2,6,6-tetra(meth)acryloyloxymethyl-4-oxaheptane. The polyfunctional (meth)acrylic polymerizable compound (C) may be used alone or in combination of two or more types.

[0046] The content of the polyfunctional (meth)acrylic polymerizable compound (C) in the dental resin composition of the present invention is preferably 5 to 75% by mass of 100% by mass of the total amount of polymerizable compounds, more preferably 10 to 60% by mass, even more preferably 15 to 50% by mass, and particularly preferably 20 to 40% by mass, from the viewpoint of superior moldability, strength of molded products, and repeated fatigue characteristics when combined with other components. Furthermore, the content of the polyfunctional (meth)acrylic polymerizable compound (C) in the dental resin composition of the present invention is preferably 1 to 80% by mass, more preferably 2.5 to 70% by mass, even more preferably 5 to 60% by mass, and particularly preferably 10 to 50% by mass, based on 100% by mass of the total amount of the dental resin composition, from the standpoint of superior moldability, strength of molded products, and repeated fatigue characteristics when combined with other components.

[0047] [Monofunctional (meth)acrylic polymerizable compounds (D) that do not contain urethane bonds] The dental resin composition of the present invention may contain a monofunctional (meth)acrylic polymerizable compound (D) that does not contain urethane bonds (hereinafter also simply referred to as "monofunctional (meth)acrylic polymerizable compound (D)") for the purpose of improving cleanability and adjusting the strength and repeated fatigue characteristics of the cured product. Furthermore, when combined with monofunctional (meth)acrylic polymerizable compound (D), the cured product exhibits superior strength and superior moldability when fabricated by stereolithography (liquid bath stereolithography). One preferred embodiment is a dental resin composition containing a monofunctional urethane-(meth)acrylic polymerizable compound (A), a photopolymerization initiator (B), and a monofunctional (meth)acrylic polymerizable compound (D) that does not contain urethane bonds. In this embodiment, the polyfunctional (meth)acrylic polymerizable compound (C) may not be included. In the above-described preferred embodiments, the monofunctional urethane-(meth)acrylic polymerizable compound (A), the photopolymerization initiator (B), and the monofunctional (meth)acrylic polymerizable compound (D) that does not contain urethane bonds, as well as the types and contents of fillers, stabilizers, additives, etc., as needed, can be changed according to the specifications.

[0048] Examples of monofunctional (meth)acrylic polymerizable compounds (D) include (meth)acrylic acid ester compounds containing aromatic rings, alicyclic (meth)acrylic acid ester compounds, heterocyclic (meth)acrylic acid ester compounds, and cyclic (meth)acrylamide compounds. Examples of (meth)acrylic acid ester compounds containing aromatic rings include o-phenylphenyl (meth)acrylate, m-phenylphenyl (meth)acrylate, p-phenylphenyl (meth)acrylate, ethoxylated-o-phenylphenol (meth)acrylate, ethoxylated-m-phenylphenol (meth)acrylate, ethoxylated-p-phenylphenol (meth)acrylate, propoxylated-o-phenylphenol (meth)acrylate, propoxylated-m-phenylphenol (meth)acrylate, propoxylated-p-phenylphenol (meth)acrylate, butoxylated-o-phenylphenol (meth)acrylate, butoxylated-m-phenylphenol (meth)acrylate, butoxylated-p-phenylphenol (meth)acrylate, diphenylmethyl (meth)acrylate, 4-(1-methyl-1-phenylethyl)(meth)acrylate, triphenylmethyl (meth)acrylate, o- Phenoxyphenyl (meth)acrylate, m-phenoxyphenyl (meth)acrylate, p-phenoxyphenyl (meth)acrylate, o-phenoxybenzyl (meth)acrylate, m-phenoxybenzyl (meth)acrylate, p-phenoxybenzyl (meth)acrylate, 2-(o-phenoxyphenyl)ethyl (meth)acrylate, 2-(m-phenoxyphenyl)ethyl (meth)acrylate, 2-(p-phenoxyphenyl)ethyl (meth) (meth)acrylic acid ester compounds containing two or more aromatic rings, such as acrylate, 3-(o-phenoxyphenyl)propyl (meth)acrylate, 3-(m-phenoxyphenyl)propyl (meth)acrylate, 3-(p-phenoxyphenyl)propyl (meth)acrylate, 9-(meth)acryloyloxyfluorene, 9-(meth)acryloyloxymethylfluorene, N-(meth)acryloylcarbazole, and N-(meth)acryloylmethylcarbazole;Examples include (meth)acrylic acid ester compounds containing one aromatic ring, such as phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxybutyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, 4-methylphenyl (meth)acrylate, 4-n-butylphenyl (meth)acrylate, 4-t-butylphenyl (meth)acrylate, 4-nonylphenyl (meth)acrylate, (meth)acrylic acid-o-2-propenylphenyl, benzhydrol (meth)acrylate, and cumylphenol (meth)acrylate. Examples of alicyclic (meth)acrylic acid ester compounds include saturated alicyclic (meth)acrylic acid ester compounds such as 1-adamantyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, 2-ethyl-2-adamantyl (meth)acrylate, and 2-isopropyl-2-adamantyl (meth)acrylate. Examples of heterocyclic (meth)acrylic acid ester compounds include nitrogen atom-containing cyclic (meth)acrylic acid ester compounds such as pentamethylpiperidinyl (meth)acrylate, tetramethylpiperidinyl (meth)acrylate, and 4-(pyrimidine-2-yl)piperazin-1-yl (meth)acrylate. Examples of cyclic (meth)acrylamide compounds include N-(meth)acryloylmorpholine, N-(meth)acryloylpyrrolidine, N-(meth)acryloylpiperidine, N-(meth)acryloyl-2-methylpiperidine, and N-(meth)acryloyl-2,2,6,6-tetramethylpiperidine. The monofunctional (meth)acrylic polymerizable compound (D) may be used alone or in combination of two or more types. As the monofunctional (meth)acrylic polymerizable compound (D), a monofunctional (meth)acrylic polymerizable compound that does not contain hydroxyl groups may be used, from the viewpoint of easily suppressing the deterioration of the physical properties of the cured product of the dental resin composition. Among these, from the viewpoint of the dental resin composition having excellent curability and the cured product having excellent repeated fatigue properties, (meth)acrylic acid ester compounds containing two or more aromatic rings, alicyclic (meth)acrylic acid ester compounds, and nitrogen atom-containing cyclic (meth)acrylic acid ester compounds are preferred, including ethoxylated-o-phenylphenol (meth)acrylate, ethoxylated-m-phenylphenol (meth)acrylate, ethoxylated-p-phenylphenol (meth)acrylate, and o-phenoxybenzyl (meth)acrylate. (T) acrylate, m-phenoxybenzyl (meth)acrylate, p-phenoxybenzyl (meth)acrylate, 2-(o-phenoxyphenyl)ethyl (meth)acrylate, 2-(m-phenoxyphenyl)ethyl (meth)acrylate, 2-(p-phenoxyphenyl)ethyl (meth)acrylate, 1-adamantyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, 2-ethyl-2-adamantyl (meth)acrylate, 2-isopropyl-2-adamantyl (meth)acrylate (T)acrylate, pentamethylpiperidinyl (meth)acrylate, tetramethylpiperidinyl (meth)acrylate, 4-(pyrimidine-2-yl)piperazin-1-yl (meth)acrylate are more preferred, ethoxylated-o-phenylphenol (meth)acrylate, m-phenoxybenzyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, 2-ethyl-2-adamantyl (meth)acrylate, 2-isopropyl-2-adamantyl (meth)acrylate, pen Tamethylpiperidinyl (meth)acrylate and tetramethylpiperidinyl (meth)acrylate are more preferred, m-phenoxybenzyl (meth)acrylate, 2-ethyl-2-adamantyl (meth)acrylate, 2-isopropyl-2-adamantyl (meth)acrylate, and pentamethylpiperidinyl (meth)acrylate are particularly preferred, and m-phenoxybenzyl methacrylate, 2-isopropyl-2-adamantyl methacrylate, and pentamethylpiperidinyl methacrylate are most preferred.

[0049] The content of the monofunctional (meth)acrylic polymerizable compound (D) in the dental resin composition of the present invention is preferably 1.0 to 60% by mass of 100% by mass of the total amount of polymerizable compounds, more preferably 2.5 to 50% by mass, even more preferably 5 to 45% by mass, and particularly preferably 10 to 40% by mass, from the viewpoint of superior curability, washability, and repeated fatigue characteristics of the cured product. Furthermore, in a preferred embodiment, the content of the monofunctional (meth)acrylic polymerizable compound (D) is preferably 5 to 80% by mass, more preferably 8 to 70% by mass, even more preferably 10 to 60% by mass, and particularly preferably 12 to 50% by mass, based on 100% by mass of the total amount of the dental resin composition, from the standpoint of superior strength and repeated fatigue characteristics of the cured product when combined with other components.

[0050] One preferred embodiment, which is superior in terms of the effects of the present invention, is a dental resin composition containing a monofunctional urethane-(meth)acrylic polymerizable compound (A), a photopolymerization initiator (B), a polyfunctional (meth)acrylic polymerizable compound (C), and a monofunctional (meth)acrylic polymerizable compound (D) that does not contain urethane bonds. In the above preferred embodiment, a dental resin composition is provided in which, based on 100% by mass of the total amount of the dental resin composition, the content of a monofunctional urethane-(meth)acrylic polymerizable compound (A) is 10 to 80% by mass, the content of a polyfunctional (meth)acrylic polymerizable compound (C) is 10 to 70% by mass, and the content of a monofunctional (meth)acrylic polymerizable compound (D) that does not contain urethane bonds is 5 to 50% by mass. In any of the preferred embodiments described above, the monofunctional urethane-(meth)acrylic polymerizable compound (A), the photopolymerization initiator (B), the polyfunctional (meth)acrylic polymerizable compound (C), and the monofunctional (meth)acrylic polymerizable compound (D) that does not contain urethane bonds, as well as the types and contents of fillers, stabilizers, additives, etc., as needed, can be changed according to the specifications.

[0051] The dental resin composition of the present invention may contain other polymerizable compounds other than monofunctional (meth)acrylic polymerizable compound (A), polyfunctional (meth)acrylic polymerizable compound (C), and monofunctional (meth)acrylic polymerizable compound (D) (hereinafter also simply referred to as "other polymerizable compounds"). Other polymerizable compounds include (meth)acrylamide oligomers (for example, those with a molecular weight of 1000 or less, those with a molecular weight of 1000 or more, etc.). In one preferred embodiment, it is preferable that the product is substantially free of (meth)acrylamide oligomers (e.g., those with a molecular weight of 1000 or less, those with a molecular weight of 1000 or more, etc.). In another preferred embodiment, a dental resin composition is provided that is substantially free of other polymerizable compounds. "Substantially free of (meth)acrylamide oligomers" means that the content of (meth)acrylamide oligomers is less than 5% by mass of the total amount of the dental resin composition, preferably less than 1% by mass, more preferably less than 0.1% by mass, and even more preferably less than 0.01% by mass. The phrase "substantially free of other polymerizable compounds" has the same meaning as "substantially free of (meth)acrylamide oligomers" in terms of the content of other polymerizable compounds.

[0052] The dental resin composition of the present invention may contain a polymerization accelerator for the purpose of improving photocurability, without sacrificing the spirit of the present invention. While the polymerization accelerator is not particularly limited, considering that the dental resin composition of the present invention is used in oral cavity applications, polymerization accelerators used in dental applications can be suitably utilized. Preferred polymerization accelerators used in known dental applications include amines. Examples of amines include aliphatic amines and aromatic amines. The polymerization accelerator may be used alone or in combination of two or more types. Examples of aromatic amines include ethyl 4-(N,N-dimethylamino)benzoate, methyl 4-(N,N-dimethylamino)benzoate, n-butoxyethyl 4-(N,N-dimethylamino)benzoate, 2-(methacryloyloxy)ethyl 4-(N,N-dimethylamino)benzoate, 4-(N,N-dimethylamino)benzophenone, and butyl 4-(N,N-dimethylamino)benzoate. Among these, at least one selected from the group consisting of ethyl 4-(N,N-dimethylamino)benzoate, n-butoxyethyl 4-(N,N-dimethylamino)benzophenone is preferably used from the viewpoint of imparting excellent curability to dental resin compositions.

[0053] The dental resin composition of the present invention may further contain fillers to adjust its liquid properties or to increase the mechanical strength of the cured product of the dental resin composition. Examples of fillers include organic fillers, inorganic fillers, and organic-inorganic composite fillers. Fillers may be used individually or in combination of two or more types.

[0054] Examples of organic filler materials include polymethyl methacrylate, polyethyl methacrylate, methyl methacrylate-ethyl methacrylate copolymer, crosslinked polymethyl methacrylate, crosslinked polyethyl methacrylate, polyester, polyamide, polycarbonate, polyphenylene ether, polyoxymethylene, polyvinyl chloride, polystyrene, polyethylene, polypropylene, chloroprene rubber, nitrile rubber, ethylene-vinyl acetate copolymer, styrene-butadiene copolymer, acrylonitrile-styrene copolymer, and acrylonitrile-styrene-butadiene copolymer. The organic filler may be used alone or in combination of two or more types. The shape of the organic filler is not particularly limited, and the particle size of the filler can be appropriately selected.

[0055] Examples of inorganic filler materials include quartz, silica, alumina, silica-titania, silica-titania-barium oxide, silica-zirconia, silica-alumina, lanthanum glass, borosilicate glass, soda glass, barium glass, strontium glass, glass ceramics, aluminosilicate glass, barium boroaluminosilicate glass, strontium boroaluminosilicate glass, fluoroaluminosilicate glass, calcium fluoroaluminosilicate glass, strontium fluoroaluminosilicate glass, barium fluoroaluminosilicate glass, and strontium calcium fluoroaluminosilicate glass. Inorganic fillers may be used individually or in combination of two or more types. The shape of the inorganic filler is not particularly limited, and irregularly shaped fillers or spherical fillers can be selected and used as appropriate. The inorganic filler content is not particularly limited as long as it does not impair the spirit of the present invention, however, since there is a concern that dental materials such as denture base materials and dental occlusal splints, and sleep disorder treatment materials may become brittle, it is generally preferable that the inorganic filler content be 50 parts by mass or less, more preferably 25 parts by mass or less, and even more preferably 10 parts by mass or less, per 100 parts by mass of the total amount of polymerizable compound.

[0056] Polymers may be added to the dental resin composition of the present invention for the purpose of modifying flexibility, fluidity, etc., as long as the spirit of the present invention is not impaired. For example, natural rubber, synthetic polyisoprene rubber, liquid polyisoprene rubber and its hydrogenated products, polybutadiene rubber, liquid polybutadiene rubber and its hydrogenated products, styrene-butadiene rubber, chloroprene rubber, ethylene-propylene rubber, acrylic rubber, isoprene-isobutylene rubber, acrylonitrile-butadiene rubber, or styrene-based elastomers can be added. Specific examples of other polymers that can be added include polystyrene-polyisoprene-polystyrene block copolymer, polystyrene-polybutadiene-polystyrene block copolymer, poly(α-methylstyrene)-polybutadiene-poly(α-methylstyrene) block copolymer, poly(p-methylstyrene)-polybutadiene-poly(p-methylstyrene) block copolymer, or hydrogenated products thereof.

[0057] The dental resin composition of the present invention may optionally contain a softening agent. Examples of softening agents include petroleum-based softening agents such as paraffin-based, naphthenic, and aromatic process oils, and vegetable oil-based softening agents such as paraffin, peanut oil, and rosin. These softening agents may be used individually or in combination of two or more. The content of the softening agent is not particularly limited as long as it does not impair the spirit of the present invention, but is usually 200 parts by mass or less, preferably 100 parts by mass or less, per 100 parts by mass of the total amount of polymerizable compound.

[0058] Furthermore, the dental resin composition of the present invention may contain known stabilizers for the purpose of suppressing degradation or adjusting photocurability. Examples of such stabilizers include polymerization inhibitors, ultraviolet absorbers, and antioxidants. The aforementioned stabilizers may be used individually or in combination of two or more types.

[0059] Examples of polymerization inhibitors include hydroquinone, hydroquinone monomethyl ether, dibutylhydroquinone, dibutylhydroquinone monomethyl ether, 4-t-butylcatechol, 2-t-butyl-4,6-dimethylphenol, 2,6-di-t-butylphenol, and 3,5-di-t-butyl-4-hydroxytoluene. The polymerization inhibitor content is preferably 0.001 to 5.0 parts by mass per 100 parts by mass of the total amount of polymerizable compound.

[0060] Furthermore, known additives may be added to the dental resin composition of the present invention for the purpose of adjusting the color tone or paste properties. Examples of such additives include pigments, dyes, organic solvents, and thickeners. The aforementioned additives may be used individually or in combination of two or more.

[0061] The dental resin composition of the present invention exhibits excellent curability, cleanability, and also superior strength and repeated fatigue characteristics of the cured product. Therefore, the dental resin composition of the present invention can be applied to applications where these advantages can be utilized, and is particularly suitable for intraoral applications. Examples of intraoral applications include dental materials such as denture base materials and dental occlusal splints; and materials for treating sleep disorders (especially devices for treating sleep apnea syndrome). The dental resin composition of the present invention is particularly suitable for denture base materials, dental occlusal splints, and devices for treating sleep apnea syndrome.

[0062] The shape of the cured product using the dental resin composition of the present invention can be changed according to each application. Furthermore, the dental resin composition of the present invention can be adjusted as needed for each application, such as denture base material, dental occlusal splint, and treatment device for sleep apnea syndrome, by adjusting the type and content of monofunctional (meth)acrylic polymerizable compounds (A), polyfunctional (meth)acrylic polymerizable compounds (C), monofunctional (meth)acrylic polymerizable compounds (D) that do not contain urethane bonds, polymerization initiators (B), and various optional components (polymerization accelerators, fillers, polymers, softeners, stabilizers, additives, etc.).

[0063] The dental resin composition of the present invention can be used in a variety of applications, taking advantage of its properties, particularly its ability to produce molded or three-dimensional objects, as well as other cured products, with low volume shrinkage, excellent dimensional accuracy, and superior strength and repeated fatigue characteristics when cured with light. For example, it can be used in the manufacture of three-dimensional objects by optical stereolithography, the manufacture of various molded products such as films or molded objects by casting or other methods, and in coatings, vacuum forming molds, etc.

[0064] Among these, the dental resin composition of the present invention is suitable for use in the optical three-dimensional molding method described above. In this case, it is possible to smoothly manufacture three-dimensional objects that have excellent molding accuracy, excellent cleanability, and excellent strength and repeated fatigue characteristics while keeping the volume shrinkage rate during photocuring low. Therefore, the dental resin composition of the present invention can be suitably used as a dental resin composition for stereolithography.

[0065] Another embodiment of the present invention is a method for manufacturing a three-dimensional object by optical stereolithography using any of the dental resin compositions described above. The optical 3D fabrication method is not particularly limited, and liquid-bath photopolymerization methods such as laser-based SLA (Stereolithography Apparatus) and DLP (digital light processing)-based SLA can be used. Low-force stereolithography (LFS) can also be used as an SLA method.

[0066] When performing optical three-dimensional fabrication using the dental resin composition of the present invention, any known optical three-dimensional fabrication method and apparatus (for example, a stereolithography machine such as the DIGITALWAX® 028J-Plus manufactured by DWS Corporation) can be used. Among these, in the present invention, it is preferable to use active energy rays as the light energy for curing the resin. "Active energy rays" refers to energy rays that can cure dental resin compositions, such as ultraviolet rays, electron beams, X-rays, radiation, and high-frequency waves. For example, the active energy ray may be ultraviolet rays having a wavelength of 300 to 400 nm. Examples of light sources for active energy rays include lasers such as Ar lasers and He-Cd lasers; and lighting such as halogen lamps, xenon lamps, metal halide lamps, LEDs, mercury lamps, and fluorescent lamps, with lasers being particularly preferred. When a laser is used as the light source, it is possible to increase the energy level and shorten the fabrication time, and moreover, by utilizing the good focusing ability of the laser beam, it is possible to obtain three-dimensional fabricated objects with high fabrication accuracy.

[0067] As described above, when performing optical three-dimensional fabrication using the dental resin composition of the present invention, any known method or known stereolithography system apparatus can be used and is not particularly limited. However, a representative example of an optical three-dimensional fabrication method preferably used in the present invention is a method in which the desired three-dimensional object is finally obtained by repeating the steps of: selectively irradiating the dental resin composition with active energy light to form a hardened layer so that a hardened layer having a desired pattern is obtained; then supplying an uncured liquid dental resin composition to the hardened layer and similarly irradiating it with active energy light to form a new hardened layer continuous with the hardened layer; and so on. Furthermore, the three-dimensional object obtained therefrom can be used as is, or, in some cases, post-curing by light irradiation or heat may be performed to further improve its mechanical properties or shape stability before use.

[0068] The structure, shape, size, etc., of the three-dimensional objects obtained by optical three-dimensional printing are not particularly limited and can be determined according to their respective applications. Typical application fields of the optical three-dimensional printing method of the present invention include the creation of models for verifying the external design during the design process; models for checking the functionality of parts; resin molds for making castings; base models for making molds; and direct molds for prototype molds. More specifically, examples include the production of models or processing models for precision parts, electrical and electronic components, furniture, building structures, automobile parts, various containers, castings, molds, matrices, etc. Taking advantage of the excellent strength and toughness of the dental resin composition, it can be used very effectively for applications such as cushioning materials with complex shapes in structures (for example, building structures) and vacuum forming molds. [Examples]

[0069] Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited in any way by these examples, and many modifications can be made by those with ordinary skill in the art within the scope of the technical idea of ​​the present invention.

[0070] The components used in the polymerizable compositions of the examples or comparative examples are described below, along with their abbreviations.

[0071] [Monofunctional (meth)acrylic polymerizable compound containing urethane bonds (A)] Monofunctional (meth)acrylic polymerizable compound containing a urethane bond (A)-1: Urethane acrylate (manufactured by Daicel Ornex Co., Ltd., trade name "KRM9276", molecular weight: 215, number of polymerizable groups (acrylic groups): 1) (referred to as "(A)-1" in the table).

[0072] <Synthesis Example 1> [Monofunctional (meth)acrylic polymerizable compound containing urethane bonds (A)-2] (1) 167 g of 2-methoxyphenyl isocyanate and 0.15 g of di-n-butyltin dilaurate were added to a 5 L four-necked flask equipped with a stirrer, temperature controller, thermometer, and condenser, and heated to 70°C with stirring. (2) Next, 150 g of 2-hydroxypropyl acrylate and 0.4 g of hydroquinone monomethyl ether, which had been added to another dropping funnel, were uniformly dissolved in the solution. This solution was then added dropwise at a constant rate to the flask from (1) over 2 hours while maintaining the internal temperature of the flask at 55-65°C. The mixture was then allowed to react for 4 hours while maintaining the temperature of the solution in the flask at 70-80°C to obtain a monofunctional (meth)acrylic polymerizable compound (A)-2 (molecular weight: 279) (referred to as "(A)-2" in the table) containing one urethane bond at one end of the molecule.

[0073] <Synthesis Example 2> [Monofunctional (meth)acrylic polymerizable compound (A)-3 containing urethane bonds] (1) 174 g of 2-ethylhexyl isocyanate and 0.15 g of di-n-butyltin dilaurate were added to a 5 L four-necked flask equipped with a stirrer, temperature controller, thermometer, and condenser, and heated to 70°C with stirring. (2) Next, 130 g of 2-hydroxyethyl acrylate and 0.4 g of hydroquinone monomethyl ether, which had been added to another dropping funnel, were uniformly dissolved in the solution. This solution was then added dropwise at a constant rate to the flask from (1) over 2 hours while maintaining the internal temperature of the flask at 55-65°C. The mixture was then allowed to react for 4 hours while maintaining the temperature of the solution in the flask at 70-80°C to obtain a monofunctional (meth)acrylic polymerizable compound (A)-3 (molecular weight: 271) (referred to as "(A)-3" in the table) containing one urethane bond at one end of the molecule.

[0074] <Synthesis Example 3> [Monofunctional (meth)acrylic polymerizable compound (A)-4 containing urethane bonds] (1) 1120 g of Uniox M1000 (polyethylene glycol monomethyl ether, molecular weight: 1000) and 0.15 g of di-n-butyltin dilaurate were added to a 5 L four-necked flask equipped with a stirrer, temperature controller, thermometer, and condenser, and the mixture was heated to 70°C with stirring. (2) Next, 174 g of 2-isocyanate ethyl methacrylate (Karenz MOI, manufactured by Karenz) and 0.4 g of hydroquinone monomethyl ether, which had been added to another dropping funnel, were uniformly dissolved in the solution. This solution was then added dropwise at a constant rate to the flask from (1) over 2 hours while maintaining the internal temperature of the flask at 55-65°C. The solution was then allowed to react for 4 hours while maintaining the temperature of the solution in the flask at 70-80°C to obtain a monofunctional (meth)acrylic polymerizable compound (A)-4 (referred to as "(A)-4" in the table) containing one urethane bond at one end of the molecule. The weight-average molecular weight Mw of the monofunctional (meth)acrylic polymerizable compound (A)-4, determined by GPC analysis, was 1100. The weight-average molecular weight (Mw) of the compounds synthesized above refers to the weight-average molecular weight in polystyrene terms, determined by gel permeation chromatography (GPC).

[0075] [Photopolymerization initiator (B)] BAPO: Bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (manufactured by IGM Resins BV (NL), "Omnirad 819") TEO: (2,4,6-trimethylbenzoyl)ethoxyphenylphosphine oxide (manufactured by Tokyo Chemical Industry Co., Ltd.)

[0076] [Polyfunctional (meth)acrylic polymerizable compound (C)-I containing urethane bonds] UDMA: 2,2,4-trimethylhexamethylenebis(2-carbamoyloxyethyl) dimethacrylate (manufactured by Kyoeisha Chemical Co., Ltd.)

[0077] <Synthesis Example 4> [Preparation of (C)-I-1, a polyfunctional (meth)acrylic polymerizable compound containing urethane bonds] (1) 250 g of isophorone diisocyanate and 0.15 g of di-n-butyltin dilaurate were added to a 5 L four-necked flask equipped with a stirrer, temperature controller, thermometer, and condenser, and heated to 70°C with stirring. (2) Meanwhile, 1200 g of polyester polyol (Kuraray Polyol® P-2050, manufactured by Kuraray Co., Ltd.; a polyol composed of sebacic acid and 3-methyl-1,5-pentanediol, weight-average molecular weight Mw2000) was added to a dropping funnel with a side tube, and the liquid from this dropping funnel was added dropwise to the flask from (1) above. The solution in the flask from (1) above was stirred, and the addition was carried out dropwise at a constant rate over 4 hours while maintaining the internal temperature of the flask at 65-75°C. After the addition was completed, the mixture was stirred at the same temperature for 2 hours to allow the reaction to proceed. (3) Next, 130 g of 2-hydroxyethyl acrylate and 0.4 g of hydroquinone monomethyl ether, which had been added to another dropping funnel, were uniformly dissolved in the solution. This solution was then added dropwise at a constant rate to the flask from (2) over 2 hours while maintaining the internal temperature of the flask at 55-65°C. The mixture was then allowed to react for 4 hours while maintaining the temperature of the solution in the flask at 70-80°C to obtain the polyfunctional (meth)acrylic polymerizable compound (C)-I-1. The weight-average molecular weight Mw of the polyfunctional (meth)acrylic polymerizable compound (C)-I-1, as determined by GPC analysis, was 2500. The weight-average molecular weight (Mw) of the compounds synthesized above refers to the weight-average molecular weight in polystyrene terms, determined by gel permeation chromatography (GPC).

[0078] [Polyfunctional (meth)acrylic polymerizable compound (C)-II that does not contain urethane bonds] D2.6E: 2,2-Bis(4-methacryloyloxypolyethoxyphenyl)propane (average number of moles of ethoxy groups added: 2.6, manufactured by Shin-Nakamura Chemical Industry Co., Ltd., "BPE-100")

[0079] [Monofunctional (meth)acrylic polymerizable compound (D)] POBMA: m-Phenoxybenzyl methacrylate (manufactured by Kyoeisha Chemical Co., Ltd.) PMPMA: Pentamethylpiperidinyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.)

[0080] [Polymerization inhibitor] BHT: 3,5-di-t-butyl-4-hydroxytoluene

[0081] [Examples 1-12 and Comparative Examples 1-5] The components were mixed in the quantities (parts by mass) shown in Tables 1 and 2 at room temperature (20°C ± 15°C, JIS (Japanese Industrial Standards) Z 8703:1983) to prepare pastes as dental resin compositions according to Examples 1 to 12 and Comparative Examples 1 to 5.

[0082] <Modeling accuracy> For each dental resin composition described in Tables 1 and 2 of the Examples and Comparative Examples, the dimensions (in mm) of the cubic test specimens were measured using a micrometer in the x, y, and z axes. After calculating the arithmetic mean of the three directions, the molding error was calculated using the following formula (n=1). This method results in superior molding accuracy when the molding error is 5.0% or less, and when fabricating aligners, denture bases, etc., it tends to produce products with excellent fit. Forming error (%) = |(measured dimensions) - 10.0| × 100 Those that could not be created were marked with an "X".

[0083] <Cleaning properties> For each example and comparative example, one 10.0 mm cube was fabricated using a stereolithography machine (DIGITALWAX® 028J-Plus, manufactured by DWS) with a 50 μm pitch and a light irradiation time of 0.6 seconds per layer. The resulting fabricated object was placed in a 300 ml glass beaker, 200 ml of isopropanol was poured in, and the object was washed for the first time in an ultrasonic cleaner for 5 minutes. After discarding the isopropanol, 200 ml of fresh isopropanol was poured in, and a second ultrasonic cleaning was performed (first pass). The fabricated object was removed from the glass beaker and allowed to air dry for 30 minutes, after which its cleanability was evaluated by touch by 10 subjects (n=1). If eight or more of the ten subjects reported no stickiness after the first wash, the cleaning was considered sufficient and the cleaning performance was rated as "A". In all other cases, after the first wash, the printed object was placed in a 300 ml glass beaker, 200 ml of isopropanol was poured in, and it was washed in an ultrasonic cleaner for 5 minutes. After washing, the printed object was removed from the glass beaker and allowed to air dry for 30 minutes, and the cleanability was evaluated again by touch (second wash). If, after the second round of washing, eight or more of the ten subjects reported no stickiness, the washing was deemed acceptable and the washing performance was rated as "B". If, even after the second round of washing, the evaluation was anything other than "B" and stickiness was reported, the washing was deemed inadequate and rated as "C".

[0084] <Strength (flexural strength, flexural modulus)> Using a stereolithography machine (DIGITALWAX® 020D, manufactured by DWS), test specimens (length 64.0 mm, width 10.0 mm, thickness 3.3 mm) with dimensions specified in JIS T 6501:2012 (Acrylic resins for denture bases) were fabricated with a pitch of 100 μm and a light irradiation time of 1.3 seconds per layer. Next, the fabricated specimens were placed in a 300 ml glass beaker, 200 ml of isopropanol was poured in, and the first ultrasonic cleaning was performed for 5 minutes. After discarding the isopropanol, 200 ml of fresh isopropanol was poured in, and a second ultrasonic cleaning was performed. The cleaned specimens were heated in a 60°C constant temperature bath for 20 minutes, then immediately removed and irradiated 6,000 times over 10 minutes at 25°C using a light curing machine (Otoflash® G171, manufactured by EnvisionTEC). The material was then immediately placed in a 60°C constant temperature bath and heated for 20 minutes to complete the secondary polymerization process, obtaining a test specimen. This specimen was then used as a molded object of the dental resin composition for a bending test. For each example and comparative example, the molded objects of the dental resin compositions were stored in air for one day, and then their strength (flexural modulus, flexural strength) and toughness (displacement at the bending fracture point) were measured. The measurements were performed using a universal testing machine (Shimadzu Corporation, Autograph AG-I 100kN) at a crosshead speed of 5 mm / min (n=5). The arithmetic mean values ​​of the measured values ​​are shown in Tables 1 and 2. In terms of flexural modulus, from the viewpoint of fit and usability as a denture base material or dental occlusal splint, a range of 200 to 4000 MPa is preferred, a range of 400 to 3500 MPa is more preferred, and a range of 600 to 3000 MPa is even more preferred. The bending strength is preferably 15 to 150 MPa, more preferably 20 to 125 MPa, and even more preferably 25 to 100 MPa.

[0085] <Repeated fatigue characteristics> Using the same method as the bending test described above, test specimens (60.0 mm in length, 10.0 mm in width, and 1.0 mm in thickness) were fabricated from the obtained dental resin composition. Subsequently, the specimens were washed and subjected to secondary polymerization treatment, similar to the strength test specimens described above. These specimens were then used as fabricated objects of the dental resin composition, and repeated bending fatigue tests were conducted to evaluate their repeated fatigue properties. Under room temperature conditions of 25°C, the long sides of the molded dental resin compositions according to each example and comparative example were held with the thumb and index finger, and the ends were bent until they touched. Then the force was released, and this process was repeated up to 20 times, and the number of times until breakage was evaluated (n=3). In this test, those that did not break were evaluated as having excellent repeated fatigue properties and were given an "A" rating. Those that broke at least once during 10 to 20 cycles were evaluated as having repeated fatigue properties and were given a "B" rating. Those that broke at least once during fewer than 10 cycles were evaluated as having insufficient fatigue properties and were given a "C" rating.

[0086] [Table 1]

[0087] [Table 2]

[0088] As shown in Table 1, the dental resin compositions in Examples 1 to 12 exhibited excellent molding accuracy and cleanability, and the molded objects had excellent strength and repeated fatigue characteristics. In comparison with Tables 1 and 2, the moldability of the dental resin compositions in Examples 1 to 12 was particularly superior to that of the resin composition in Comparative Example 1. Furthermore, a comparison with Tables 1 and 2 showed that the cleaning properties of the dental resin compositions in Examples 1 to 12 were superior to those of the resin compositions in Comparative Examples 2, 3, and 5. Furthermore, a comparison with Tables 1 and 2 shows that the strength of the molded objects produced by the dental resin compositions of Examples 1 to 12 was superior to that of the resin compositions of Comparative Examples 2 and 3. Furthermore, a comparison with Tables 1 and 2 shows that the repeated fatigue characteristics of the dental resin compositions used in Examples 1 to 12 were superior to those of the resin compositions used in Comparative Examples 3 and 4. [Industrial applicability]

[0089] The dental resin composition of the present invention is excellent in terms of cleanability, molding accuracy, strength of molded objects, and repeated fatigue characteristics, making it suitable for oral applications such as various dental materials (especially denture base materials and dental occlusal splints) or various sleep disorder treatment materials (especially treatment devices for sleep apnea syndrome).

Claims

1. A dental resin composition containing a monofunctional urethane-based (meth)acrylic polymerizable compound (A) and a photopolymerization initiator (B).

2. The dental resin composition according to claim 1, further comprising a polyfunctional (meth)acrylic polymerizable compound (C) and / or a monofunctional (meth)acrylic polymerizable compound (D) that does not contain a urethane bond.

3. The dental resin composition according to claim 1 or 2, wherein the molecular weight of the monofunctional urethane-(meth)acrylic polymerizable compound (A) is 1000 or less.

4. The dental resin composition according to claim 1 or 2, wherein the polyfunctional (meth)acrylic polymerizable compound (C) contains a polyfunctional (meth)acrylic polymerizable compound (C)-I containing a urethane bond.

5. The dental resin composition according to claim 4, comprising a monofunctional (meth)acrylic polymerizable compound (D) that does not contain urethane bonds.

6. A dental resin composition according to claim 1 or 2, wherein the dental resin composition is for use in stereolithography.

7. A dental occlusal splint comprising a cured product of the dental resin composition according to claim 1 or 2.

8. A denture base material comprising a cured product of the dental resin composition according to claim 1 or 2.

9. A method for manufacturing a three-dimensional object by optical stereolithography using the dental resin composition described in claim 1 or 2.

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