Stereolithographic resin composition

Abstract

The present invention provides a stereolithographic resin composition from which a shaped article having excellent strength, toughness, water resistance, and impact resistance is obtained. The present invention pertains to a stereolithographic resin composition containing: a polyfunctional (meth)acrylic polymerizable compound (A) having a molecular weight of less than 1,000; a polyfunctional (meth)acrylic polymerizable compound (B) having a molecular weight of at least 1,000; a monofunctional (meth)acrylic polymerizable compound (C) that does not contain a hydroxyl group and contains a cyclic ether structure; and a photopolymerization initiator (D).

Description

Resin composition for stereolithography

[0001] The present invention relates to a stereolithography resin composition. More specifically, the present invention can produce a three-dimensional object having excellent strength, toughness, water resistance, and impact resistance. The composition is particularly suitable for dental occlusal splints, denture base materials, and treatment devices for sleep apnea syndrome, and is particularly suitable for soft dental occlusal splints.

[0002] Many proposals have been made regarding so-called optical three-dimensional modeling methods, which involve repeating the process of supplying a required amount of controlled light energy to a liquid photocurable resin to harden it into a thin layer, supplying more liquid photocurable resin on top of it, and then irradiating it with light under control to harden the resulting thin layer.

[0003] A typical method for optically producing a three-dimensional object is liquid vat stereolithography, in which the liquid surface of a liquid photocurable resin composition placed in a container is selectively irradiated with a computer-controlled ultraviolet laser to obtain the desired pattern, curing the composition to a predetermined thickness and forming a cured layer. Next, a layer of liquid photocurable resin composition is supplied on top of the cured layer, and similarly irradiated with an ultraviolet laser to cure the composition in the same manner as above, forming successive cured layers. This lamination process is repeated to produce a three-dimensional object of the final shape. This method has attracted considerable attention in recent years because it can produce the desired three-dimensional object easily, in a relatively short time, and with high accuracy, even if the object has a fairly complex shape.

[0004] The applications of three-dimensional objects obtained by stereolithography have expanded from mere concept models to test models, prototypes, and final products. In particular, in the field of dental materials, applications of stereolithography are expected to be expanded for dental occlusal splints, denture bases, and mouthpiece-type sleep disorder treatment materials such as devices for preventing teeth grinding and treating sleep apnea syndrome, because the shapes vary from patient to patient and are complex.

[0005] Dental occlusal splints are devices worn to correct the alignment of teeth and jaw position, such as orthodontic mouthpieces and aligners, devices worn on the teeth to prevent tooth wear due to teeth grinding, and mouthguards worn in the oral cavity to reduce trauma caused by large external forces applied to the teeth and jawbone during contact sports and to protect the stomatognathic system and brain. In recent years, the use of orthodontic devices has rapidly expanded due to their aesthetic appeal and the ability to be removed whenever desired.

[0006] Denture base materials are materials used in the gum area when wearing dentures due to tooth loss. In recent years, the demand for dentures has increased dramatically due to the increase in the elderly population.

[0007] A device for treating sleep apnea syndrome is an apparatus (oral appliance: OA) that is attached to the teeth while sleeping at night to treat obstructive sleep apnea syndrome (OSAS), and its use is rapidly increasing.

[0008] Dental occlusal splints, denture base materials, and OAs all require strength, toughness, water resistance, and impact resistance. Low strength leads to significant deflection and deformation during wear, resulting in an uncomfortable fit. Loss of toughness leads to problems such as breakage due to occlusal loads and deformation during wear, necessitating frequent remaking. Loss of water resistance also leads to problems such as a decline in mechanical properties during use, making the splint more susceptible to deformation and breakage during wear, making it unsuitable for practical use. Furthermore, there is a risk of the splint being accidentally dropped during removal or cleaning, and low impact resistance can easily cause breakage.

[0009] Furthermore, when producing dental occlusal splints, denture base materials, and treatment devices for sleep apnea syndrome, it is usually necessary to take an impression of the oral cavity, but problems have been pointed out, such as the discomfort it causes to the patient and the need for skilled laboratory procedures. In recent years, with the development of digital technology, attempts have been made to apply optical intraoral scanning to impression taking, and optical three-dimensional modeling to molding. Stereolithography resin compositions are used in modeling, but generally, the stronger a resin composition is, the more brittle it tends to become. On the other hand, when attempting to impart toughness, i.e., flexibility, the molecular structure becomes flexible, making it more susceptible to moisture penetration, making it difficult to satisfy all of the strength, toughness, water resistance, and impact resistance requirements.

[0010] Against this background, as a technology for obtaining optically three-dimensional objects having excellent strength, toughness, and impact resistance, for example, Patent Document 1 discloses a resin composition for stereolithography containing, as essential components, a urethane acrylate oligomer having a polyester skeleton, a urethane acrylate oligomer having a polyether skeleton, and a specific di(meth)acrylic acid ester compound having a dioxane skeleton.

[0011] International Publication No. 2020 / 136919

[0012] However, after investigations by the present inventors, it was found that although the cured product of the stereolithography resin composition described in Patent Document 1 is somewhat excellent in strength, toughness, impact resistance, and fatigue properties, there is no mention of water resistance, and after investigations by the present inventors, it was found that there is room for improvement in water resistance.

[0013] Therefore, an object of the present invention is to provide a stereolithography resin composition that is excellent in strength, toughness, water resistance, and impact resistance.

[0014] The present invention encompasses the following inventions: [1] A stereolithography resin composition containing a polyfunctional (meth)acrylic polymerizable compound (A) having a molecular weight of less than 1,000, a polyfunctional (meth)acrylic polymerizable compound (B) having a molecular weight of 1,000 or more, a monofunctional (meth)acrylic polymerizable compound (C) having no hydroxyl group and containing a cyclic ether structure, and a photopolymerization initiator (D); [2] The stereolithography resin composition according to [1], wherein the polyfunctional (meth)acrylic polymerizable compound (A) is a (meth)acrylate having no polymer structure in one molecule; [3] The stereolithography resin composition according to [1] and / or [2], wherein the polyfunctional (meth)acrylic polymerizable compound (A) contains a polyfunctional urethane-modified (meth)acrylic polymerizable compound (A)-I having a urethane bond; [4] The stereolithography resin composition according to any one of [1] to [3], wherein the polyfunctional (meth)acrylic polymerizable compound (B) contains a polyfunctional urethane-modified (meth)acrylic polymerizable compound (B)-I containing a urethane bond; [5] The stereolithography resin composition according to [4], wherein the polyfunctional urethane-modified (meth)acrylic polymerizable compound (B)-I is a (meth)acrylate containing, in one molecule, at least one structure selected from the group consisting of polyester, polycarbonate, polyurethane, polyether, polyconjugated diene, and hydrogenated polyconjugated diene; [6] The stereolithography resin composition according to [5], wherein the polyfunctional urethane-modified (meth)acrylic polymerizable compound (B)-I is a (meth)acrylate containing, in one molecule, at least one polyol moiety selected from the group consisting of polyester, polycarbonate, polyurethane, polyether, polyconjugated diene, and hydrogenated polyconjugated diene, having a structure derived from an aliphatic chain diol unit having 4 to 18 carbon atoms and a branched structure; [7] The stereolithography resin composition according to any one of [1] to [6], wherein the cyclic ether structure of the monofunctional (meth)acrylic polymerizable compound (C) is dioxane; [8] The stereolithography resin composition according to any one of [1] to [7], wherein the monofunctional (meth)acrylic polymerizable compound (C) is mono(meth)acrylate;[9] The stereolithography resin composition according to any one of [1] to [7], wherein the monofunctional (meth)acrylic polymerizable compound (C) is at least one selected from the group consisting of (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, (2-methyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, (2-ethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, 2-((2-methyl-1,3-dioxolan-4-yl)methoxy)ethyl (meth)acrylate, 2-((2-ethyl-1,3-dioxolan-4-yl)methoxy)ethyl (meth)acrylate, and cyclic trimethylolpropane formal (meth)acrylate;

[10] A dental material comprising an article shaped from the stereolithography resin composition according to any one of [1] to [9];

[11] A denture base material comprising an article shaped from the stereolithography resin composition according to any one of [1] to [9];

[12] A dental occlusal splint comprising an article shaped from the stereolithography resin composition according to any one of [1] to [9];

[13] A sleep disorder treatment material comprising an article shaped from the stereolithography resin composition according to any one of [1] to [9];

[14] A method for producing a three-dimensional object by a stereolithography method using the stereolithography resin composition according to any one of [1] to [9];

[0015] The stereolithography resin composition of the present invention provides a molded object with excellent strength, toughness, water resistance, and impact resistance, and is therefore suitable for dental occlusal splints and denture base materials, as well as for use as a material for treatment devices for sleep apnea syndrome.

[0016] The present invention will be described in detail below using embodiments. In this specification, the upper and lower limits of numerical ranges (such as the content of each component, values ​​calculated from each component, and physical properties) can be combined as appropriate. For example, in this specification, the lower and upper limits of numerical ranges described in stages can be independently combined. For example, a description of the same item as "preferably 0.2 to 8.0 mass%, more preferably 0.5 to 5.0 mass%" can be combined with the "preferable lower limit (0.2 mass%)" and the "more preferable upper limit (5.0 mass%)" to yield "0.2 to 5.0 mass%" or 0.5 to 8.0 mass%. Furthermore, regarding a numerical range, for example, based on the description "more preferably 12 to 28 mass%, and even more preferably 12.5 to 25 mass%, " the upper limit can be specified without any particular upper limit, and only the lower limit can be specified as "12 mass% or more" or "12.5 mass% or more". Similarly, the lower limit can be specified without any particular lower limit, and only the upper limit can be specified as "28 mass% or less" or "25 mass% or less". Unless otherwise specified, when a numerical range is simply described as "30 to 70", it represents a range of 30 to 70. Furthermore, for example, when the numerical range is "25 mass% or more and 75 mass% or less", the boundary of the numerical range can be selected from any of "more than 25 mass%, "25 mass% or more", "75 mass% or less", and "less than 75 mass%". As above, for example, from the description "more preferably 0.05 parts by mass or more, even more preferably 0.1 parts by mass or more" and the description "more preferably 15 parts by mass or less, even more preferably 10 parts by mass or less" for the same item, the "more preferable lower limit (0.05 parts by mass or more)" and the "more preferable upper limit (10 parts by mass or less)" can be combined to form "0.05 parts by mass or more and 10 parts by mass or less." Also, as above, only the lower limit can be specified as "0.05 parts by mass or more" or "0.1 parts by mass or more," and similarly, only the upper limit can be specified as "15 parts by mass or less" or "10 parts by mass or less." The numerical ranges described above have merely been explained using mass % and parts by mass as examples, and the same applies to molecular weight, etc.

[0017] In this specification, the term "polymerizable compound" refers to a polymerizable compound that is polymerized by the photopolymerization initiator (D) described below. In this specification, the term "(meth)acrylic" encompasses both "methacrylic" and "acrylic." The same applies to similar terms such as "(meth)acrylate," "(meth)acrylic acid ester," "(meth)acrylamide," and "(meth)acryloyloxy." In this specification, the term "(meth)acrylic polymerizable compound" encompasses 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 this specification, the term "multifunctional" refers to a compound having more than one polymerizable group. In this specification, the term "molecular weight" refers to a single value calculated from atomic weights when an oligomer or polymer structure is not included. In the case of an oligomer or polymer structure having two or more repeating units, the term "molecular weight" refers to the weight average molecular weight, unless otherwise specified, and refers to the weight average molecular weight calculated in terms of polystyrene standards by gel permeation chromatography (GPC).

[0018] The stereolithography resin composition of the present invention contains a polyfunctional (meth)acrylic polymerizable compound (A) having a molecular weight of less than 1,000, a polyfunctional (meth)acrylic polymerizable compound (B) having a molecular weight of 1,000 or more, a monofunctional (meth)acrylic polymerizable compound (C) which does not contain a hydroxyl group and contains a cyclic ether structure, and a photopolymerization initiator (D).

[0019] [Polyfunctional (meth)acrylic polymerizable compound (A) having a molecular weight of less than 1000] The polyfunctional (meth)acrylic polymerizable compound (A) having a molecular weight of less than 1000 (hereinafter also simply referred to as "polyfunctional (meth)acrylic polymerizable compound (A)") is used in the stereolithography resin composition of the present invention to impart shapeability to the stereolithography resin composition and to impart strength and toughness to the shaped object.

[0020] From the viewpoint of excellent water resistance, the polyfunctional (meth)acrylic polymerizable compound (A) having a molecular weight of less than 1000 preferably does not contain a polymer structure in one molecule, and more preferably is a (meth)acrylate that does not contain a polymer structure in one molecule. When it does not contain a polymer structure, the content of the repeating unit of the polar functional group per molecule becomes small, so that it tends to have excellent water resistance. Examples of the polymer structure include polyester, polycarbonate, polyurethane, polyether, polyamide, polyimide, polyarylate, polyacrylate, etc.

[0021] Examples of the polyfunctional (meth)acrylic polymerizable compound (A) include a polyfunctional urethane-modified (meth)acrylic polymerizable compound (A)-I containing a urethane bond (hereinafter also simply referred to as "polyfunctional urethane-modified (meth)acrylic polymerizable compound (A)-I"), and a polyfunctional (meth)acrylic polymerizable compound (A)-II not containing a urethane bond (hereinafter also simply referred to as "polyfunctional (meth)acrylic polymerizable compound (A)-II"). From the viewpoint of excellent toughness of a shaped object, it is preferable to contain the polyfunctional urethane-modified (meth)acrylic polymerizable compound (A)-I, and it is more preferable that the polyfunctional urethane-modified (meth)acrylic polymerizable compound (A)-I is a (meth)acrylate that does not contain a polymer structure in one molecule.

[0022] The polyfunctional urethane-modified (meth)acrylic polymerizable compound (A)-I can be easily synthesized, for example, by addition reaction of a compound having an isocyanate group containing an alkylene skeleton or a phenylene skeleton with a (meth)acrylic compound having a hydroxyl group (—OH). Examples of the compound having an isocyanate group and the (meth)acrylic compound having a hydroxyl group (—OH) include the same compounds as those exemplified in the production of the polyfunctional urethane-modified (meth)acrylic polymerizable compound (B)-I described below. The addition reaction can be carried out using known methods and conditions, and is not particularly limited.

[0023] Examples of the polyfunctional urethane-modified (meth)acrylic polymerizable compound (A)-I include 2,2,4-trimethylhexamethylenebis(2-carbamoyloxyethyl)dimethacrylate (commonly known as UDMA), 2,4-tolylenebis(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, 2,4-tolylenebis(2- Examples of suitable urethane-modified (meth)acrylates include polyfunctional urethane-modified (meth)acrylates of 2,2,4-trimethylhexamethylenebis(2-carbamoyloxyethyl)dimethacrylate; phenyl glycidyl ether (meth)acrylate hexamethylene diisocyanate urethane prepolymer, pentaerythritol tri(meth)acrylate hexamethylene diisocyanate urethane prepolymer, pentaerythritol tri(meth)acrylate toluene diisocyanate urethane prepolymer, and pentaerythritol tri(meth)acrylate isophorone diisocyanate urethane prepolymer. These may be used alone or in combination of two or more. Among these, from the viewpoint of the strength and toughness of the shaped object, 2,2,4-trimethylhexamethylenebis(2-carbamoyloxyethyl)dimethacrylate and phenyl glycidyl ether acrylate hexamethylene diisocyanate urethane prepolymer are preferred, and 2,2,4-trimethylhexamethylenebis(2-carbamoyloxyethyl)dimethacrylate is more preferred.

[0024] The content of the polyfunctional urethane-type (meth)acrylic polymerizable compound (A)-I in the polyfunctional (meth)acrylic polymerizable compound (A) is preferably 20% by mass or more, more preferably 40% by mass or more, even more preferably 60% by mass or more, and most preferably 80% by mass or more, based on 100% by mass of the total amount of the polyfunctional (meth)acrylic polymerizable compound (A), from the viewpoint of achieving superior strength and toughness of the shaped object. Furthermore, the content of the polyfunctional urethane-type (meth)acrylic polymerizable compound (A)-I in the polyfunctional (meth)acrylic polymerizable compound (A) may be 100% by mass.

[0025] Examples of the polyfunctional (meth)acrylic polymerizable compound (A)-I include bifunctional (meth)acrylic polymerizable compounds and trifunctional or higher functional (meth)acrylic polymerizable compounds, and from the viewpoint of the toughness and impact resistance of the shaped product, bifunctional (meth)acrylic polymerizable compounds are preferred.

[0026] Examples of the polyfunctional (meth)acrylic polymerizable compound (A)-II include bifunctional (meth)acrylic polymerizable compounds and trifunctional or higher functional (meth)acrylic polymerizable compounds, and from the viewpoint of the toughness and impact resistance of the shaped product, bifunctional (meth)acrylic polymerizable compounds are preferred.

[0027] Examples of the polyfunctional (meth)acrylic polymerizable compound (A)-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)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)acryloyloxy 2,2-bis(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-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,Examples include 2-bis(3-methacryloyloxy-2-hydroxypropoxy)ethane and tricyclodecane dimethanol di(meth)acrylate.

[0028] Examples of the tri- or higher functional polymerizable compound 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.

[0029] The molecular weight of the polyfunctional urethane-modified (meth)acrylic polymerizable compound (A) must be less than 1,000, and from the viewpoint of strength and impact resistance, it is preferably 250 to 900, more preferably 300 to 800.

[0030] The content of the polyfunctional (meth)acrylic polymerizable compound (A) in the stereolithography resin composition of the present invention is preferably 10 to 80% by mass, based on 100% by mass of the total amount of polymerizable compounds, and from the viewpoint of achieving superior strength, toughness, water resistance, and impact resistance of a molded object when combined with other components, it is more preferably 20 to 70% by mass, even more preferably 30 to 60% by mass, and most preferably 40 to 50% by mass. The polyfunctional (meth)acrylic polymerizable compound (A) may be used alone or in combination of two or more types. Furthermore, the content of the polyfunctional (meth)acrylic polymerizable compound (A) in the stereolithography resin composition of the present invention is preferably 10 to 80 mass%, more preferably 20 to 70 mass%, even more preferably 30 to 60 mass%, and most preferably 40 to 50 mass%, based on the total amount (100 mass) of the stereolithography resin composition, in order to obtain a molded object with superior strength, toughness, water resistance, and impact resistance when combined with other components.

[0031] [Polyfunctional (meth)acrylic polymerizable compound (B) having a molecular weight of 1000 or more] The polyfunctional (meth)acrylic polymerizable compound (B) having a molecular weight of 1000 or more (hereinafter also referred to simply as "polyfunctional (meth)acrylic polymerizable compound (B)") is used in the stereolithography resin composition of the present invention to impart toughness and impact resistance to a molded object.

[0032] The polyfunctional (meth)acrylic polymerizable compound (B) is classified into a polyfunctional (meth)acrylic polymerizable compound containing an oligomer or polymer structure and a polyfunctional (meth)acrylic polymerizable compound not containing an oligomer or polymer structure. However, from the viewpoint of excellent strength, toughness, and impact resistance of a molded object when combined with other components, it is preferable to contain a polyfunctional (meth)acrylic polymerizable compound containing an oligomer or polymer structure. Furthermore, examples of the polyfunctional (meth)acrylic polymerizable compound (B) include a polyfunctional urethane-modified (meth)acrylic polymerizable compound (B)-I containing a urethane bond (hereinafter also simply referred to as "polyfunctional urethane-modified (meth)acrylic polymerizable compound (B)-I") and a polyfunctional (meth)acrylic polymerizable compound (B)-II not containing a urethane bond. However, from the viewpoint of excellent toughness and impact resistance of a molded object, it is preferable to contain a polyfunctional urethane-modified (meth)acrylic polymerizable compound (B)-I.

[0033] The polyfunctional urethane-modified (meth)acrylic polymerizable compound (B)-I containing an oligomer or polymer structure can be easily synthesized by addition reaction of a polyol having a polymer skeleton such as a polymer structure of polyester, polycarbonate, polyurethane, polyether, polydiene, or hydrogenated polydiene, a compound having an isocyanate group (-NCO), and a (meth)acrylic compound having a hydroxyl group (-OH). Alternatively, the compound can be easily synthesized by ring-opening addition reaction of a lactone or alkylene oxide with a (meth)acrylic compound having a hydroxyl group, followed by addition reaction of the resulting compound having a hydroxyl group at one end with a compound having an isocyanate group.

[0034] The polyfunctional urethane-modified (meth)acrylic polymerizable compound (B)-I is preferably a (meth)acrylate containing, in one molecule, at least one structure selected from the group consisting of polyester, polycarbonate, polyurethane, polyether, polyconjugated diene, and hydrogenated polyconjugated diene.

[0035] In the above structure, examples of the polyester include copolymers of dicarboxylic acids (e.g., aromatic dicarboxylic acids such as phthalic acid and isophthalic acid; unsaturated aliphatic dicarboxylic acids such as maleic acid) and aliphatic diols having 2 to 18 carbon atoms, copolymers of dicarboxylic acids (e.g., saturated aliphatic dicarboxylic acids such as adipic acid and sebacic acid) and aliphatic diols having 2 to 18 carbon atoms, β-propiolactone polymers, γ-butyrolactone polymers, δ-valerolactone polymers, ε-caprolactone polymers, and copolymers thereof, and preferred are copolymers of dicarboxylic acids (preferably aromatic dicarboxylic acids, unsaturated aliphatic dicarboxylic acids) and aliphatic diols having 2 to 12 carbon atoms, and copolymers of dicarboxylic acids (preferably saturated aliphatic dicarboxylic acids) and aliphatic glycols 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, with 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 being 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 hydrogenated products thereof. Among these, polyester structures are preferred because of their excellent toughness and water resistance.

[0036] In terms of superior strength, impact resistance, and water resistance, the polyfunctional urethane-modified (meth)acrylic polymerizable compound (B)-I is preferably a (meth)acrylate containing, in one molecule, at least one polyol moiety selected from the group consisting of polyesters, polycarbonates, polyurethanes, polyethers, polyconjugated dienes, and hydrogenated polyconjugated dienes, each having a structure derived from a branched aliphatic chain diol unit having 4 to 18 carbon atoms. Examples of the polyester include copolymers having a structure derived from a branched aliphatic chain diol unit having 4 to 18 carbon atoms and a structure derived from an unbranched aliphatic chain dicarboxylic acid and / or aromatic dicarboxylic acid unit having 4 to 18 carbon atoms. Examples of the polycarbonate include copolymers having a structure derived from a branched aliphatic chain diol unit having 4 to 18 carbon atoms and a structure derived from an unbranched aliphatic chain diol unit having 4 to 18 carbon atoms. Examples of the polyurethane include a polycondensate of a structure derived from a branched aliphatic chain diol unit having 4 to 18 carbon atoms and a diisocyanate compound. Examples of the polyether include a polyether having a structure derived from a branched aliphatic chain diol unit having 4 to 18 carbon atoms, and a polyether having a structure derived from a non-branched aliphatic chain diol unit having 4 to 18 carbon atoms. Examples of the polyconjugated diene include a homopolymer or copolymer of a conjugated diene monomer. Examples of the conjugated diene monomer include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and 1,3-hexadiene. Examples of the hydrogenated polyconjugated diene include hydrogenated polybutadiene, hydrogenated polyisoprene, and hydrogenated polyisobutylene.Among these, in terms of excellent toughness, water resistance, and impact resistance, it is preferable that the polymer skeleton contains at least one structure selected from the group consisting of polyesters, polycarbonates, polyethers, and hydrogenated polyconjugated dienes, it is more preferable that the polymer skeleton contains at least one structure selected from the group consisting of polyesters and polycarbonates, and it is even more preferable that the polymer skeleton contains at least one structure selected from the group consisting of polyesters.

[0037] Examples of diols constituting the aliphatic chain diol unit having 4 to 18 carbon atoms and a branched structure include 2-methyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 1,3-butanediol, 2-methyl-1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2-methyl-1,8-octanediol, 2,7-dimethyl-1,8-octanediol, 2-methyl-1,9-nonanediol, 2,8-dimethyl-1,9-nonanediol, 2-methyl-1,10-decanediol, 2,9-dimethyl-1,10-decanediol, 2-methyl-1,1 Examples of the diol include 1-undecanediol, 2,10-dimethyl-1,11-undecanediol, 2-methyl-1,12-dodecanediol, 2,11-dimethyl-1,12-dodecanediol, 2-methyl-1,13-tridecanediol, 2,12-dimethyl-1,13-tridecanediol, 2-methyl-1,14-tetradecanediol, 2,13-dimethyl-1,14-tetradecanediol, 2-methyl-1,15-pentadecanediol, 2,14-dimethyl-1,15-pentadecanediol, 2-methyl-1,16-hexadecanediol, and 2,15-dimethyl-1,16-hexadecanediol. Among these, from the viewpoint of achieving excellent curability and low viscosity in the stereolithography resin composition, it is preferable to use an aliphatic diol having 5 to 12 carbon atoms and having a methyl group as a side chain, such as 2-methyl-1,4-butanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,8-octanediol, 2,7-dimethyl-1,8-octanediol, 2-methyl-1,9-nonanediol, or 2,8-dimethyl-1,9-nonanediol, as the polyol; 2-methyl-1,4-butanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,8-octanediol, or 2,7-dimethyl-1,8-octanediol are more preferable, and 3-methyl-1,5-pentanediol or 2-methyl-1,8-octanediol are even more preferable.

[0038] Examples of compounds having an isocyanate group include hexamethylene diisocyanate (HDI), tolylene diisocyanate (TDI), xylylene diisocyanate (XDI), diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI), trimethylhexamethylene diisocyanate (TMHMDI), tricyclodecane diisocyanate (TCDDI), and adamantane diisocyanate (ADI).

[0039] Examples of the (meth)acrylic compound 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. hydroxy(meth)acrylate compounds such as dipentaerythritol, 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.

[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] Examples of the polyfunctional urethane-modified (meth)acrylic polymerizable compound (B)-I that does not contain a polymer structure include dipentaerythritol penta(meth)acrylate hexamethylene diisocyanate urethane prepolymer.

[0042] The molecular weight of the polyfunctional urethane-modified (meth)acrylic polymerizable compound (B)-I must be 1,000 or more, and from the viewpoint of strength and impact resistance, it is preferably 1,500 to 5,000, more preferably 2,000 to 3,000.

[0043] Examples of the polyfunctional urethane-modified (meth)acrylic polymerizable compound (B)-I include bifunctional (meth)acrylic polymerizable compounds and trifunctional or higher functional (meth)acrylic polymerizable compounds.

[0044] The content of the polyfunctional urethane-type (meth)acrylic polymerizable compound (B)-I in the polyfunctional (meth)acrylic polymerizable compound (B) is preferably 20% by mass or more, more preferably 40% by mass or more, even more preferably 60% by mass or more, and most preferably 80% by mass or more, based on 100% by mass of the total amount of the polyfunctional (meth)acrylic polymerizable compound (B), in order to obtain a shaped object having superior strength, water resistance, toughness, and impact resistance when combined with other components. Furthermore, the content of the polyfunctional urethane-type (meth)acrylic polymerizable compound (B)-I in the polyfunctional (meth)acrylic polymerizable compound (B) may be 100% by mass.

[0045] In some embodiments, the content of the polyfunctional urethane-type (meth)acrylic polymerizable compound (B)-I is preferably 1 to 70% by mass, more preferably 5 to 60% by mass, even more preferably 10 to 50% by mass, and most preferably 20 to 40% by mass, relative to 100% by mass of the total amount of the polymerizable compounds, in order to provide a shaped object with better strength, water resistance, toughness, and impact resistance when combined with other components.

[0046] Examples of the polyfunctional (meth)acrylic polymerizable compound (B)-II that does not contain a urethane bond include bifunctional (meth)acrylic polymerizable compounds and trifunctional or higher functional (meth)acrylic polymerizable compounds.

[0047] Examples of the polyfunctional (meth)acrylic polymerizable compound (B)-II not containing a urethane bond include 2,2-bis(4-(meth)acryloyloxypolyethoxyphenyl)propane (for example, average number of moles of ethoxy groups added: 25 or more), polyethylene glycol di(meth)acrylate, and the like.

[0048] The content of the polyfunctional (meth)acrylic polymerizable compound (B) in the stereolithography resin composition of the present invention is preferably 1 to 80% by mass, more preferably 5 to 70% by mass, even more preferably 10 to 60% by mass, and most preferably 20 to 50% by mass, based on 100% by mass of the total amount of the polymerizable compounds, in order to obtain a molded object with superior strength, toughness, water resistance, and impact resistance when combined with other components. The polyfunctional (meth)acrylic polymerizable compound (B) may be used alone or in combination of two or more types. Furthermore, the content of the polyfunctional (meth)acrylic polymerizable compound (B) in the stereolithography resin composition of the present invention is preferably 10 to 60 mass %, more preferably 15 to 65 mass %, even more preferably 20 to 50 mass %, and most preferably 25 to 45 mass %, based on the total amount (100 mass %) of the stereolithography resin composition, in order to obtain a molded object with superior strength, toughness, water resistance, and impact resistance when combined with other components.

[0049] [Monofunctional (meth)acrylic polymerizable compound (C) containing no hydroxyl group and having a cyclic ether structure] The monofunctional (meth)acrylic polymerizable compound (C) containing no hydroxyl group and having a cyclic ether structure (hereinafter also simply referred to as "monofunctional (meth)acrylic polymerizable compound (C)") is used in the stereolithography resin composition of the present invention to reduce viscosity and impart strength, impact resistance, toughness, and water resistance to the shaped object.

[0050] The monofunctional (meth)acrylic polymerizable compound (C) is composed of one polymerizable group, a spacer group, and a ring structure having one or more ether groups. In other words, one polymerizable group is bonded to a ring structure having one or more ether groups via a spacer group. Therefore, compounds having a structure in which one polymerizable group is bonded directly to a ring structure having one or more ether groups without a spacer group (e.g., N-acryloylmorpholine, etc.) are not included in the monofunctional (meth)acrylic polymerizable compound (C). The polymerizable group of the monofunctional (meth)acrylic polymerizable compound (C) is preferably a (meth)acryloxy group. The spacer group is preferably a linear or branched alkylene group having 1 to 10 carbon atoms. Examples of the alkylene group include a methylene group, an ethylene group, an n-propylene group, an isopropylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group, a heptamethylene group, and an octamethylene group. The number of carbon atoms in the spacer group is preferably 1 to 8, more preferably 1 to 6, still more preferably 1 to 4, and particularly preferably 1 to 3.

[0051] The monofunctional (meth)acrylic polymerizable compound (C) does not contain a hydroxyl group because, if it contains a hydroxyl group, the glass transition temperature (Tg) of the homopolymer tends to be high and the water resistance is poor. Furthermore, if the (meth)acrylic polymerizable compound that does not contain a hydroxyl group and does not contain a cyclic ether structure is bifunctional or higher in relation to other components, sufficient toughness, water resistance, and impact resistance cannot be obtained.

[0052] The cyclic ether structure possessed by the monofunctional (meth)acrylic polymerizable compound (C) is not particularly limited as long as it is a ring structure having one or more ether groups (—O—). However, a ring structure having no unsaturated bond is preferred. A heterocyclic structure containing an oxygen atom and a nitrogen atom may also be used. However, from the viewpoint of superior water resistance, a ring structure composed of an oxygen atom and a carbon atom and having no unsaturated bond is more preferred. Specifically, an oxacycloalkane is preferred. Examples of oxacycloalkanes include ring structures containing one or more oxygen atoms, such as oxacyclopropane (oxirane), oxacyclobutane (oxetane), oxacyclopentane (tetrahydrofuran), oxacyclohexane (tetrahydropyran), dioxacyclohexane (dioxane), and trioxacyclohexane rings. From the viewpoint of superior strength, impact resistance, and water resistance of the cured product of the stereolithography resin composition of the present invention, a ring structure containing two or more atoms is preferred, and a ring structure containing two oxygen atoms is more preferred. Furthermore, a five-membered or larger ring is preferred, and a five- to eight-membered ring is more preferred as the ring structure. These ring structures may contain a substituent, such as an alkyl group having 1 to 5 carbon atoms. On the other hand, in order to prevent the effects of the cyclic ether structure (particularly water resistance) from being impaired, it is preferable that the ring structure not be directly bonded to an oxo group, a nitroso group, a nitro group, or the like. A preferred embodiment includes a stereolithography resin composition in which the cyclic ether structure possessed by the monofunctional (meth)acrylic polymerizable compound (C) is a ring structure that does not contain an oxo group. For example, when dioxolane or dioxane contains an oxo group, a carbonate group (—O—(C═O)—O—) is formed, resulting in excessive polarity and significantly reduced water resistance. The number of heteroatoms possessed by the ring structure may be one or more, and may be two or more. However, two is preferred in terms of lowering the boiling point of the compound, making it easier to suppress odor generation, and providing excellent impact resistance.Among these, from the viewpoint of achieving superior strength and impact resistance of the cured product of the stereolithography resin composition of the present invention when combined with other components, dioxolane (1,2-dioxolane, 1,3-dioxolane, etc.), oxacyclopentane (tetrahydrofuran), oxacyclohexane (tetrahydropyran), and dioxacyclohexane (dioxane) are preferred, dioxane is more preferred, dioxolane and dioxane are even more preferred, and dioxane is particularly preferred from the viewpoint of achieving particularly superior impact resistance. The position of the oxygen atom in these rings is not particularly limited, and the dioxane may be any of 1,2-dioxane, 1,3-dioxane, and 1,4-dioxane.

[0053] The glass transition temperature (Tg) of the homopolymer of the monofunctional (meth)acrylic polymerizable compound (C) is preferably 50°C or lower, more preferably 45°C or lower, and even more preferably 40°C or lower. The glass transition temperature (Tg) of the homopolymer of the monofunctional (meth)acrylic polymerizable compound (C) is preferably −20°C or higher, more preferably −15°C or higher, and even more preferably 5°C or higher. Furthermore, when the glass transition temperature (Tg) of the homopolymer of the monofunctional (meth)acrylic polymerizable compound (C) is close to the actual use temperature of the shaped object, for example, in the case of intraoral use (preferably dental material use), the homopolymer tends to have particularly excellent impact resistance when the glass transition temperature (Tg) is in the range from near room temperature to a temperature corresponding to body temperature, specifically 15°C to 40°C. The glass transition temperature (Tg) of the homopolymer can be measured by a conventionally known method using, for example, a viscoelasticity measuring device (rheometer) or a differential scanning calorimeter (DSC). Specifically, the Tg of the homopolymer can be determined by measuring the dynamic viscoelasticity of the homopolymer of the monofunctional (meth)acrylic polymerizable compound (C) using a rotational rheometer ("AR2000" manufactured by TA Instruments Japan Inc.), and in this dynamic viscoelasticity measurement, the frequency is set to 10 Hz, the load is set to 10 N, the displacement is set to 0.1%, and the torque is set to 20 μNm, and the temperature at which tan δ reaches a peak can be determined as the glass transition temperature Tg.

[0054] Examples of the monofunctional (meth)acrylic polymerizable compound (C) containing a cyclic ether structure include epoxy group-containing (meth)acrylates such as glycidyl (meth)acrylate, 2-epoxyethyl (meth)acrylate, 3-epoxypropyl (meth)acrylate, 4-epoxybutyl (meth)acrylate, 5-epoxypentyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, and 3,4-epoxycyclohexylethyl (meth)acrylate; furan ring-containing (meth)acrylates such as tetrahydrofurfuryl (meth)acrylate; oxetane ring-containing (meth)acrylates such as (3-ethyloxetan-3-yl)methyl (meth)acrylate; and (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate. dioxolane ring-containing (meth)acrylates such as (2-methyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, (2-ethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, 2-((2-methyl-1,3-dioxolan-4-yl)methoxy)ethyl (meth)acrylate, and 2-((2-ethyl-1,3-dioxolan-4-yl)methoxy)ethyl (meth)acrylate; dioxane ring-containing (meth)acrylates such as cyclic trimethylolpropane formal (meth)acrylate (also known as (5-ethyl-1,3-dioxan-5-yl)methyl (meth)acrylate); and mono(meth)acrylates of tetrahydropyran ring-containing (meth)acrylates such as 2-[(2-tetrahydropyranyl)oxy]ethyl (meth)acrylate.Among these, from the viewpoint of excellent strength and impact resistance of the cured product of the stereolithography resin composition of the present invention, tetrahydrofurfuryl (meth)acrylate, (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, (2-methyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, (2-ethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, 2-((2-methyl-1,3-dioxolan-4-yl)methoxy)ethyl (meth)acrylate, 2-((2-ethyl-1,3-dioxolan-4-yl)methoxy)ethyl (meth)acrylate, cyclic trimethylolpropane formal (meth)acrylate, 2-[(2-tetrahydropyranyl ) oxy]ethyl (meth)acrylate is preferred, and (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, (2-methyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, (2-ethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, 2-((2-methyl-1,3-dioxolan-4-yl)methoxy)ethyl (meth)acrylate, 2-((2-ethyl-1,3-dioxolan-4-yl)methoxy)ethyl (meth)acrylate, and cyclic trimethylolpropane formal (meth)acrylate are more preferred, and cyclic trimethylolpropane formal (meth)acrylate is even more preferred from the viewpoint of particularly excellent impact resistance.

[0055] The content of the monofunctional (meth)acrylic polymerizable compound (C) in the stereolithography resin composition of the present invention is preferably 1.0 to 60% by mass, based on 100% by mass of the total amount of polymerizable compounds. From the viewpoints of being able to achieve a low viscosity of the stereolithography resin composition when combined with other components without impairing the strength, toughness, and water resistance, and of achieving excellent strength and impact resistance of the molded object, the content is more preferably 5.0 to 50% by mass, even more preferably 10 to 40% by mass, and most preferably 15 to 30% by mass. The monofunctional (meth)acrylic polymerizable compound (C) may be used alone or in combination of two or more types.

[0056] In some embodiments, the content of the monofunctional (meth)acrylic polymerizable compound (C) is preferably 1.0 to 60% by mass, more preferably 5.0 to 50% by mass, even more preferably 10 to 40% by mass, and most preferably 15 to 30% by mass, based on 100% by mass of the total amount of the stereolithography resin composition, in order to obtain a molded object having superior strength, water resistance, and impact resistance when combined with other components.

[0057] In another preferred embodiment, the mass ratio of the content of the monofunctional (meth)acrylic polymerizable compound (C) to the content of the polyfunctional (meth)acrylic polymerizable compound (A) is preferably (A) / (C)>1. When the content of the polyfunctional (meth)acrylic polymerizable compound (A) is greater than the content of the monofunctional (meth)acrylic polymerizable compound (C), the strength, water resistance, and impact resistance of a shaped object are improved when combined with other components. Furthermore, in another preferred embodiment, the mass ratio of the content of the monofunctional (meth)acrylic polymerizable compound (C) to the content of the polyfunctional (meth)acrylic polymerizable compound (B) is preferably (B) / (C)>1. When the content of the polyfunctional (meth)acrylic polymerizable compound (B) is greater than the content of the monofunctional (meth)acrylic polymerizable compound (C), the strength, water resistance, and impact resistance of a shaped object are improved when combined with other components. Furthermore, in another preferred embodiment, the mass ratio of the content of the monofunctional (meth)acrylic polymerizable compound (C) to the total content of the polyfunctional (meth)acrylic polymerizable compound (A) and the polyfunctional (meth)acrylic polymerizable compound (B) is preferably ((A) + (B)) / (C) > 1. When the total content of the polyfunctional (meth)acrylic polymerizable compound (A) and the polyfunctional (meth)acrylic polymerizable compound (B) is greater than the content of the functional (meth)acrylic polymerizable compound (C), the strength, toughness, water resistance, and impact resistance of the shaped object are superior. The mass ratio ((A) + (B)) / (C) is more preferably 1.5 or greater, even more preferably 2 or greater, and most preferably 3 or greater. The mass ratio ((A) + (B)) / (C) is preferably 20 or less, more preferably 15 or less, even more preferably 10 or less, and most preferably 6 or less.

[0058] In a preferred embodiment, the composition contains a polyfunctional (meth)acrylic polymerizable compound (A) having a molecular weight of less than 1000, a polyfunctional (meth)acrylic polymerizable compound (B) having a molecular weight of 1000 or more, a monofunctional (meth)acrylic polymerizable compound (C) having no hydroxyl group and containing a cyclic ether structure, and a photopolymerization initiator (D), wherein the polyfunctional (meth)acrylic polymerizable compound (A) contains a polyfunctional urethane-modified (meth)acrylic polymerizable compound (A)-I containing a urethane bond, the functional urethane-modified (meth)acrylic polymerizable compound (A)-I is a (meth)acrylate containing no polymer structure in one molecule, and the polyfunctional (meth)acrylic polymerizable compound (B) contains a polyfunctional urethane-modified (meth)acrylic polymerizable compound (B)-I containing a urethane bond, The stereolithography resin composition may be such that the polyfunctional urethane-modified (meth)acrylic polymerizable compound (B)-I is a (meth)acrylate containing, in one molecule, at least one structure selected from the group consisting of polyester, polycarbonate, polyurethane, polyether, polyconjugated diene, and hydrogenated polyconjugated diene, and the cyclic ether structure of the monofunctional (meth)acrylic polymerizable compound (C) is dioxane. In the preferred embodiment, the functional (meth)acrylic polymerizable compound (C) is preferably a mono(meth)acrylate containing dioxane as the cyclic ether structure. Furthermore, in the preferred embodiment, the polyfunctional urethane-modified (meth)acrylic polymerizable compound (B)-I is preferably a (meth)acrylate containing, in one molecule, at least one polyol moiety selected from the group consisting of polyester, polycarbonate, polyurethane, polyether, polyconjugated diene, and hydrogenated polyconjugated diene, each of which has a structure derived from an aliphatic chain diol unit having 4 to 18 carbon atoms and a branched structure. In any of the preferred embodiments described above, it is preferable that the composition is substantially free of (meth)acrylamide oligomers (for example, those having a molecular weight of 1000 or less, those having a molecular weight of 1000 or more, etc.)."Substantially free of (meth)acrylamide oligomers" means that the content of (meth)acrylamide oligomers is less than 5% by mass, preferably less than 1% by mass, more preferably less than 0.1% by mass, and even more preferably less than 0.01% by mass, based on 100% by mass of the total amount of the stereolithography resin composition. In any of the preferred embodiments described above, the type and content of each component can be changed as appropriate based on the description in this specification.

[0059] [Photopolymerization initiator (D)] The photopolymerization initiator (D) used in the present invention can be selected from polymerization initiators used in general industry, and among them, photopolymerization initiators used for dental purposes are preferred.

[0060] Examples of the photopolymerization initiator (D) include (bis)acylphosphine oxides, thioxanthones or quaternary ammonium salts of thioxanthones, ketals, α-diketones, coumarins, anthraquinones, benzoin alkyl ether compounds, α-aminoketone compounds, etc. One type of photopolymerization initiator (D) may be used alone, or two or more types may be used in combination.

[0061] Among these photopolymerization initiators (D), it is preferable to use at least one selected from the group consisting of (bis)acylphosphine oxides and α-diketones, which allows for the production of a stereolithography resin composition that is excellent in photocurability in the ultraviolet and visible light regions and exhibits sufficient photocurability when using any of the light sources, including lasers, halogen lamps, light-emitting diodes (LEDs), and xenon lamps.

[0062] Among the (bis)acylphosphine oxides, examples of the acylphosphine oxides include 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,6-dimethoxybenzoyldiphenylphosphine oxide, 2,6-dichlorobenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylmethoxyphenylphosphine oxide, 2,4,6-trimethylbenzoylethoxyphenylphosphine 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 ammonium salt of 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, bis(2,5,6-trimethylbenzoyl)-2,4,4-trimethylpentylphosphine oxide, etc. Further examples include the compounds described in JP-A-2000-159621.

[0063] Among these (bis)acylphosphine oxides, it is particularly preferable to use 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylmethoxyphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and 2,4,6-trimethylbenzoylphenylphosphine oxide sodium salt as the photopolymerization initiator (D).

[0064] 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 a light source in the visible light range is used.

[0065] The content of the photopolymerization initiator (D) in the stereolithography resin composition of the present invention is not particularly limited. However, from the viewpoint of the curability of the resulting stereolithography resin composition, the content of the photopolymerization initiator (D) is preferably 0.01 to 20 parts by mass per 100 parts by mass of the total polymerizable compounds. If the content of the photopolymerization initiator (D) is less than 0.01 parts by mass, polymerization may not proceed sufficiently, and a molded product may not be obtained. The content of the photopolymerization initiator (D) 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. On the other hand, if the content of the photopolymerization initiator (D) exceeds 20 parts by mass, if the solubility of the polymerization initiator itself is low, precipitation from the stereolithography resin composition may occur. The content of the photopolymerization initiator (D) 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.

[0066] The stereolithography resin composition of the present invention is not particularly limited as long as it contains the above-mentioned polyfunctional (meth)acrylic polymerizable compound (A) having a molecular weight of less than 1000, polyfunctional (meth)acrylic polymerizable compound (B) having a molecular weight of 1000 or more, monofunctional (meth)acrylic polymerizable compound (C) containing a cyclic ether structure, and photopolymerization initiator (D), and may contain, for example, other components. The method for producing the stereolithography resin composition of the present invention is not particularly limited, and the stereolithography resin composition of the present invention can be produced in accordance with known methods for producing stereolithography resin compositions.

[0067] The stereolithography resin composition of the present invention may contain a polymerization accelerator for the purpose of improving photocurability, as long as the accelerator does not impair the scope of the present invention. Examples of polymerization accelerators 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)benzoate, and 4-(N,N-dimethylamino)benzophenone is preferred from the viewpoint of imparting excellent curability to the stereolithography resin composition.

[0068] The stereolithography resin composition of the present invention may further contain a filler in order to adjust the paste properties or to increase the mechanical strength of an object molded from the stereolithography resin composition. Examples of the filler include organic fillers, inorganic fillers, and organic-inorganic composite fillers. One type of filler may be used alone, or two or more types may be used in combination.

[0069] Examples of organic filler materials include polymethyl methacrylate, polyethyl methacrylate, methyl methacrylate-ethyl methacrylate copolymer, cross-linked polymethyl methacrylate, cross-linked 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. These may be used alone or in combination of two or more. The shape of the organic filler is not particularly limited, and the particle size of the filler can be appropriately selected and used.

[0070] 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 ceramic, aluminosilicate glass, barium boroaluminosilicate glass, strontium boroaluminosilicate glass, fluoroaluminosilicate glass, calcium fluoroaluminosilicate glass, strontium fluoroaluminosilicate glass, barium fluoroaluminosilicate glass, and strontium calcium fluoroaluminosilicate glass. These may also be used alone or in combination of two or more. The shape of the inorganic filler is not particularly limited, and irregular fillers, spherical fillers, etc. may be appropriately selected and used.

[0071] Polymers can be added to the stereolithography resin composition of the present invention to improve flexibility, fluidity, etc., within the scope of the present invention. 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 copolymers, polystyrene-polybutadiene-polystyrene block copolymers, poly(α-methylstyrene)-polybutadiene-poly(α-methylstyrene) block copolymers, poly(p-methylstyrene)-polybutadiene-poly(p-methylstyrene) block copolymers, and hydrogenated products thereof.

[0072] The stereolithography resin composition of the present invention may contain a softener, if necessary. Examples of softeners include petroleum-based softeners such as paraffinic, naphthenic, and aromatic process oils, and vegetable oil-based softeners such as paraffin, peanut oil, and rosin. These softeners may be used alone or in combination. The content of the softener is not particularly limited as long as it does not impair the spirit of the present invention, but is typically 200 parts by mass or less, and preferably 100 parts by mass or less, per 100 parts by mass of the total amount of polymerizable compounds.

[0073] The stereolithography resin composition of the present invention may further contain a known stabilizer for the purpose of suppressing deterioration or adjusting photocurability. Examples of the stabilizer include a polymerization inhibitor, an ultraviolet absorber, and an antioxidant.

[0074] Examples of the polymerization inhibitor 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 content of the polymerization inhibitor is preferably 0.001 to 5.0 parts by mass per 100 parts by mass of the total amount of the polymerizable compounds.

[0075] The stereolithography resin composition of the present invention may further contain known additives, such as pigments, dyes, organic solvents, and thickeners, for the purpose of adjusting the color tone or paste properties.

[0076] The stereolithography resin composition of the present invention not only has excellent shaping properties, but also produces shaped objects with excellent strength, toughness, water resistance, and impact resistance. Therefore, the stereolithography resin composition of the present invention can be used in applications that utilize these advantages, such as intraoral applications. Examples of intraoral applications include denture base materials, dental materials such as dental occlusal splints, and materials for treating sleep disorders (particularly, devices for treating sleep apnea syndrome). The stereolithography resin composition of the present invention is particularly suitable for dental occlusal splints, denture base materials, and devices for treating sleep apnea syndrome.

[0077] The shape of an object molded using the stereolithography resin composition of the present invention can be changed depending on the intended use. Furthermore, the types and contents of the polyfunctional (meth)acrylic polymerizable compound (A), the polyfunctional (meth)acrylic polymerizable compound (B), the monofunctional (meth)acrylic polymerizable compound (C), the photopolymerization initiator (D), and various optional components (polymerization accelerator, filler, polymer, softener, stabilizer, additive, etc.) can be adjusted as needed for each intended use, such as a dental occlusal splint, a denture base material, or a treatment device for sleep apnea syndrome.

[0078] The stereolithography resin composition of the present invention can be used in a variety of applications by taking advantage of its properties, particularly the property that when cured with light, it can produce molded products or three-dimensional objects, as well as other objects, that have a small volumetric shrinkage rate and excellent dimensional accuracy, and that the strength, toughness, water resistance, and impact resistance of the objects are excellent.For example, it can be used in the production of three-dimensional objects by optical stereolithography, the production of various molded products such as film-like objects or molded objects by casting or casting, and in coating and vacuum forming molds, etc.

[0079] Among these, the resin composition for photopolymerization of the present invention is suitable for use in the above-mentioned optical three-dimensional modeling method, and in this case, it is possible to smoothly produce three-dimensional objects that have excellent dimensional accuracy, toughness, and mechanical properties while maintaining a small volume shrinkage rate during photocuring.

[0080] The stereolithography resin composition of the present invention has excellent strength, toughness, water resistance, and impact resistance, and has moderate flexibility without being too high in mechanical properties. Therefore, among intraoral applications, it can be particularly suitably used as orthodontic mouthpieces or aligners for the purpose of correcting the tooth alignment and / or jaw position, or soft dental splints such as sports mouthguards.

[0081] Another embodiment of the present invention is a method for producing a three-dimensional object by a stereolithography method using any of the stereolithography resin compositions described above. The stereolithography method is not particularly limited, and a liquid vat photopolymerization method such as a laser-type stereolithography apparatus (SLA) or a digital light processing (DLP)-type SLA can be used. Examples of SLA include low force stereolithography (LFS).

[0082] When performing stereolithography using the stereolithography resin composition of the present invention, any known stereolithography method and device (e.g., a stereolithography machine such as the DIGITALWAX (registered trademark) 028J-Plus manufactured by DWS) 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 capable of curing the stereolithography resin composition, such as ultraviolet rays, electron beams, X-rays, radiation, and high frequency waves. For example, the active energy rays 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. Lasers are particularly preferred. When a laser is used as a light source, it is possible to increase the energy level and shorten the modeling time, and the excellent focusing properties of the laser beam can be utilized to obtain a three-dimensional object with high modeling accuracy.

[0083] As described above, when performing stereolithography using the stereolithography resin composition of the present invention, any known method and known stereolithography system may be used, and there are no particular limitations. However, a representative example of a stereolithography method preferably used in the present invention is a method in which a stereolithography resin composition is selectively irradiated with an active energy ray to form a cured layer having a desired pattern, followed by a lamination step of supplying an uncured liquid stereolithography resin composition to the cured layer and similarly irradiating it with an active energy ray to form a new cured layer continuous with the cured layer, thereby finally obtaining the desired three-dimensional object. The three-dimensional object thus obtained may be used as is, or, in some cases, may be further post-cured by light irradiation or heat to further improve its mechanical properties or shape stability before use.

[0084] The structure, shape, size, etc. of a three-dimensional object obtained by the optical three-dimensional modeling method are not particularly limited and can be determined depending on the respective applications. Typical applications of the optical three-dimensional modeling method of the present invention include the production of models for verifying the appearance design during the design process, models for checking the functionality of parts, resin molds for producing casting molds, base models for producing metal molds, and direct molds for prototype molds. More specifically, examples include the production of models for precision parts, electrical and electronic parts, furniture, architectural structures, automotive parts, various containers, castings, metal molds, master molds, etc., or models for processing. In particular, the excellent strength and toughness of the objects produced by the stereolithography resin composition can be utilized to extremely effectively apply to applications such as cushioning materials with complex shapes in structures (e.g., architectural structures), vacuum molding molds, etc.

[0085] Next, the present invention will be explained in more detail by way of examples, but the present invention is not limited to these examples in any way, and many modifications can be made by a person having ordinary skill in the art within the scope of the technical idea of ​​the present invention.

[0086] Each component used in the polymerizable composition according to the Examples or Comparative Examples will be explained below together with its abbreviation.

[0087] [Polyfunctional urethanized (meth)acrylic polymerizable compound (A)-I] UDMA: 2,2,4-trimethylhexamethylenebis(2-carbamoyloxyethyl)dimethacrylate (manufactured by Kyoeisha Chemical Co., Ltd., molecular weight: 471) AH-600: phenyl glycidyl ether acrylate hexamethylene diisocyanate urethane prepolymer (manufactured by Kyoeisha Chemical Co., Ltd., molecular weight: 612) U4TH: N,N'-(2,2,4-trimethylhexamethylene)bis[2-(aminocarboxy)propane-1,3-diol]tetramethacrylate (manufactured by Kyoeisha Chemical Co., Ltd., molecular weight: 673) [Polyfunctional (meth)acrylic polymerizable compound (A)-II not containing a urethane bond] D2.6E: 2,2-bis(4-methacryloyloxypolyethoxyphenyl)propane (average number of moles of ethoxy groups added: 2.6, "BPE-100" manufactured by Shin-Nakamura Chemical Co., Ltd., molecular weight: approximately 478)

[0088] [Polyfunctional urethanized (meth)acrylic polymerizable compound (B)-I] <Synthesis Example 1> [Production of polyfunctional urethanized (meth)acrylic polymerizable compound (B)-I-1] (1) 250 g of isophorone diisocyanate and 0.15 g of di-n-butyltin dilaurate were added to a 5 L four-neck flask equipped with a stirrer, a temperature regulator, a thermometer, and a condenser, and the mixture was heated to 70° C. with stirring. (2) Meanwhile, 2500 g of polyester polyol ("Kuraray Polyol (registered trademark) P-2050" manufactured by Kuraray Co., Ltd.; a polyol composed of sebacic acid and 3-methyl-1,5-pentanediol, weight average molecular weight Mw: 2000) was added to a dropping funnel equipped with a side tube, and the liquid in the dropping funnel was added dropwise to the flask (1) above. The solution in the flask (1) was added dropwise at a constant rate over 4 hours while stirring and 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, a solution prepared by uniformly dissolving 150 g of 2-hydroxyethyl acrylate and 0.4 g of hydroquinone monomethyl ether in a separate dropping funnel was added dropwise at a constant rate over 2 hours to the flask (2) while maintaining the internal temperature of the flask at 55-65°C. The reaction was then continued for 4 hours while maintaining the temperature of the solution in the flask at 70-80°C, yielding a urethane-modified (meth)acrylic polymerizable compound (B)-I-1. The weight-average molecular weight Mw of the polyfunctional urethane-modified (meth)acrylic polymerizable compound (B)-I-1 was determined by GPC analysis to be 2600.

[0089] The weight average molecular weight Mw of the compound synthesized above means the weight average molecular weight in terms of polystyrene determined by gel permeation chromatography (GPC).

[0090] Multifunctional urethane-modified (meth)acrylic polymerizable compound (B)-I-2: polyether-based urethane acrylate, molecular weight: 1600, "NK Oligo UA-160™" manufactured by Shin-Nakamura Chemical Co., Ltd.

[0091] [Polyfunctional (meth)acrylic polymerizable compound (B)-II) not containing a urethane bond] A-BPE-30: 2,2-bis(4-methacryloyloxypolyethoxyphenyl)propane (average number of moles of ethoxy groups added: 30, "A-BPE-30" manufactured by Shin-Nakamura Chemical Co., Ltd., molecular weight: approximately 1656)

[0092] [Monofunctional (meth)acrylic polymerizable compound (C)] CTMPFA: cyclic trimethylolpropane formal acrylate (manufactured by SARTOMER, Tg of homopolymer: 32°C) MEDOMA: (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate ("MEDOL-10" manufactured by Osaka Organic Chemical Industry Ltd., Tg of homopolymer: -7°C)

[0093] [Photopolymerization initiator (D)] TPO: 2,4,6-trimethylbenzoyldiphenylphosphine oxide

[0094] [Polymerization inhibitor] BHT: 3,5-di-t-butyl-4-hydroxytoluene

[0095] [Examples 1 to 9 and Comparative Examples 1 to 5] The components were mixed at room temperature (20°C ± 15°C, JIS (Japanese Industrial Standards) Z 8703:1983) in the amounts (parts by mass) shown in Tables 1 and 2 to prepare pastes as stereolithography resin compositions according to Examples 1 to 9 and Comparative Examples 1 to 5.

[0096] The resulting stereolithography resin composition was used to create a test piece (length 64.0 mm, width 10.0 mm, thickness 3.3 mm) with dimensions specified in JDMAS 253:2020 (Photopolymerizable resin for 3D printers for dental hard splints) 6.4 using a stereolithography machine (DIGITALWAX® 020D manufactured by DWS). Various tests were performed on this test piece as a cured product of the stereolithography resin composition.

[0097] <Strength (Flexural Modulus, Flexural Strength), Toughness (Flexural Displacement at Break)> For the cured products of the stereolithography resin compositions according to each Example and Comparative Example, after one day of storage in air, the strength (flexural modulus, flexural strength) and toughness (flexural displacement at break) were measured. Measurements were performed in accordance with JDMAS 253:2020 (Photopolymerizable Resins for 3D Printers for Dental Hard Splints) 6.4 using a universal testing machine (Shimadzu Corporation, Autograph AG-I 100kN) at a support distance of 50 mm and a crosshead speed of 5 mm / min (n = 5). The average values ​​of the measured values ​​are shown in Tables 1 and 2. The flexural modulus is preferably in the range of 300 MPa or more but less than 1500 MPa, more preferably 400 MPa or more but less than 1000 MPa, and even more preferably 500 MPa or more but less than 750 MPa, since it is particularly suitable for use as a dental soft splint. The bending strength (three-point bending strength) is preferably 10 MPa or more, more preferably 15 MPa or more, and even more preferably 20 MPa or more. The bending strength is preferably less than 50 MPa, as this is particularly suitable for use as a dental soft splint. As for the displacement at break, it is preferable that there is no break. The displacement at break was evaluated according to the following criteria, with "A" (good toughness) and "B" (moderate toughness) being considered acceptable. <Evaluation criteria> A: The cured product broke with a displacement of 15 mm or more. B: The cured product broke with a displacement of more than 10 mm but less than 15 mm. C: The cured product broke with a displacement of 10 mm or less.

[0098] <Water Resistance> For the cured products of the stereolithography resin compositions according to each Example and Comparative Example, after immersion in water at 37°C for 168 hours, the flexural strength was measured in the same manner as in the flexural strength test described above (n=5). The average values ​​of the measured values ​​are shown in Tables 1 and 2. When the measurement result of the flexural strength for the above toughness is taken as the initial flexural strength, if the rate of change (decrease) in flexural strength shown below is 20% or less, the product has excellent water resistance. In Tables 1 and 2, the flexural strength after immersion in water at 37°C for 168 hours is referred to as "flexural strength after immersion." Rate of change (decrease) in flexural strength (%) = [{initial flexural strength (MPa) - flexural strength after immersion in water at 37°C for 168 hours (MPa)} / initial flexural strength (MPa)] x 100

[0099] <Impact Resistance> For the cured products of the stereolithography resin compositions according to each Example and Comparative Example, the cured products were placed on two test piece supports of a bending test jig, and a φ5 / 8 inch SUS304 steel ball (stainless steel ball, model number: SUS-5 / 8, available from the ASONE Research Equipment Catalog) was allowed to freely drop from a height of 80 cm or 60 cm to impact the center of the cured product. It is preferable that the cured product does not break in this test. Impact resistance was evaluated according to the following criteria, with "A" (particularly good impact resistance) and "B" (good impact resistance) being considered acceptable. <Evaluation Criteria> A: The cured product did not break when the steel ball was dropped from a height of 80 cm. B: The cured product did not break when the steel ball was dropped from a height of 60 cm, but broke when the steel ball was dropped from a height of 80 cm. C: The cured product broke when the steel ball was dropped from a height of 60 cm.

[0100]

[0101]

[0102] As shown in Tables 1 and 2, the objects molded using the stereolithography resin compositions of Examples 1 to 9 were excellent in strength, toughness, water resistance, and impact resistance due to the integration of each component. In particular, the strength and water resistance of the objects molded using the stereolithography resin compositions of Examples 1 to 9 were superior to those of the resin compositions of Comparative Examples 1 and 4. Furthermore, the toughness of the objects molded using the stereolithography resin compositions of Examples 1 to 9 was superior to those of the resin compositions of Comparative Examples 2 and 5. Furthermore, the impact resistance of the objects molded using the stereolithography resin compositions of Examples 1 to 9 was superior to those of the resin compositions of Comparative Examples 2 and 5.

[0103] Comparison of Example 1 with Comparative Examples 1 and 4 confirmed that a combination of components in a stereolithography resin composition that does not contain a polyfunctional (meth)acrylic polymerizable compound (A) does not provide sufficient strength. Comparison of Example 1 with Comparative Example 2 confirmed that a combination of components in a stereolithography resin composition that does not contain a polyfunctional (meth)acrylic polymerizable compound (B) does not provide both toughness and impact resistance. Comparative Example 3 confirmed that a resin composition that does not contain a monofunctional (meth)acrylic polymerizable compound (C) could not be molded. As shown in Comparative Example 5, it was confirmed that a combination of components using dioxane di(meth)acrylate described in Patent Document 1 does not provide sufficient toughness, water resistance, and impact resistance for intraoral use.

[0104] The stereolithography resin composition of the present invention has excellent strength, toughness, water resistance, and impact resistance in the molded objects, and is therefore suitable for intraoral applications such as various dental materials (particularly dental occlusal splints and denture base materials) and various sleep disorder treatment materials (particularly treatment devices for sleep apnea syndrome), and is particularly ideal for soft dental occlusal splints used in orthodontic mouthpieces, sports mouthguards, etc.

Claims

1. A resin composition for stereolithography, comprising (A) a polyfunctional (meth)acrylic polymerizable compound having a molecular weight of less than 1,000, (B) a polyfunctional (meth)acrylic polymerizable compound having a molecular weight of 1,000 or more, (C) a monofunctional (meth)acrylic polymerizable compound which does not contain a hydroxyl group and contains a cyclic ether structure, and (D) a photopolymerization initiator.

2. The stereolithography resin composition according to claim 1, wherein the polyfunctional (meth)acrylic polymerizable compound (A) is a (meth)acrylate that does not contain a polymer structure within one molecule.

3. The stereolithography resin composition according to claim 1 or 2, wherein the polyfunctional (meth)acrylic polymerizable compound (A) contains a polyfunctional urethane-modified (meth)acrylic polymerizable compound (A)-I containing a urethane bond.

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

5. The stereolithography resin composition according to claim 4, wherein the polyfunctional urethane-type (meth)acrylic polymerizable compound (B)-I is a (meth)acrylate containing, in one molecule, at least one structure selected from the group consisting of polyester, polycarbonate, polyurethane, polyether, polyconjugated diene, and hydrogenated polyconjugated diene.

6. The stereolithography resin composition according to claim 5, wherein the polyfunctional urethane-type (meth)acrylic polymerizable compound (B)-I is a (meth)acrylate containing at least one polyol moiety selected from the group consisting of polyesters, polycarbonates, polyurethanes, polyethers, polyconjugated dienes, and hydrogenated polyconjugated dienes, each of which has a structure derived from an aliphatic chain diol unit having 4 to 18 carbon atoms and a branched structure in one molecule.

7. The stereolithography resin composition according to claim 1 or 2, wherein the cyclic ether structure of the monofunctional (meth)acrylic polymerizable compound (C) is dioxane.

8. The stereolithography resin composition according to claim 1 or 2, wherein the monofunctional (meth)acrylic polymerizable compound (C) is a mono(meth)acrylate.

9. The stereolithography resin composition according to claim 1 or 2, wherein the monofunctional (meth)acrylic polymerizable compound (C) is at least one selected from the group consisting of (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, (2-methyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, (2-ethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, 2-((2-methyl-1,3-dioxolan-4-yl)methoxy)ethyl (meth)acrylate, 2-((2-ethyl-1,3-dioxolan-4-yl)methoxy)ethyl (meth)acrylate, and cyclic trimethylolpropane formal (meth)acrylate.

10. A dental material comprising an object molded from the stereolithography resin composition according to claim 1 or 2.

11. A denture base material comprising an object molded from the stereolithography resin composition according to claim 1 or 2.

12. A dental occlusal splint comprising an object molded from the stereolithography resin composition according to claim 1 or 2.

13. A material for treating sleep disorders, comprising an object molded from the stereolithography resin composition according to claim 1 or 2.

14. A method for producing a three-dimensional object by optical three-dimensional modeling using the resin composition for stereolithography according to claim 1 or 2.

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