JP7508315B2 - Resin composition for stereolithography - Google Patents

Description

The present invention relates to a resin composition for stereolithography. More specifically, the present invention relates to a resin composition for stereolithography that, when modeled by a stereolithography method (e.g., a suspended liquid tank stereolithography method), is easy to model due to its low viscosity and excellent curing properties, and can give a three-dimensional object that has high strength, high elasticity, and excellent abrasion resistance.

A method for producing a three-dimensional object by repeatedly applying a required amount of controlled light energy to a liquid photocurable resin to harden it into a thin layer, then applying more liquid photocurable resin on top of it and irradiating it with light under controlled conditions to harden it into a thin layer, is known as optical three-dimensional modeling.

A typical method for optically manufacturing a three-dimensional object is a liquid tank photolithography method, 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 a desired pattern, cured to a predetermined thickness, and a cured layer is formed. Next, one layer of liquid photocurable resin composition is supplied onto the cured layer, and the composition is cured in the same manner as above by irradiating the ultraviolet laser to form a continuous cured layer. This lamination process is repeated to manufacture a three-dimensional object of the final shape. This method has attracted much attention in recent years because it can easily and accurately manufacture the desired three-dimensional object in a relatively short time, even if the object has a fairly complex shape. Furthermore, while a method was previously used in which a model was lowered in a container containing a large amount of liquid photocurable resin composition, a lifting method that requires only a small amount of liquid photocurable resin composition and has little loss is becoming mainstream recently.

The uses of the three-dimensional objects obtained by stereolithography have expanded from mere concept models to test models, prototypes, etc., and as a result, there is an increasing demand for these three-dimensional objects to have excellent molding precision. In addition to these properties, they are also required to have excellent properties suited to their intended use. In particular, in the field of dental materials, the application of stereolithography is expected for prosthetics such as crowns and bridges, which have different shapes for each individual patient and are complex in shape, but the molding precision (modeling ability) and mechanical properties required are extremely high. In general, good molding precision is achieved with materials that have high hardening properties and low viscosity. On the other hand, methods for improving the strength and elastic modulus of the cured product generally include the addition of a monomer that exhibits high strength to the resin composition for stereolithography, or the addition of inorganic particles. However, many monomers that exhibit high strength have high viscosity, and when they are mixed into a resin composition for stereolithography, the viscosity increases, making modeling difficult. In addition, when inorganic particles are added, the viscosity also increases, making modeling difficult. In addition, the wear resistance tends to decrease because the filler is more likely to fall off. In addition to the dental material field, in the industrial field, industrial parts that were previously molded by injection molding can now be molded into more complex and highly functional structures by optical stereolithography, and applications are progressing as lightweight and inexpensive mold replacements and model materials. However, these applications often require not only molding precision, but also replacement of metals or engineering plastics, and as a resin material, extremely high levels of physical properties such as strength and wear resistance are required.

Against this background, Patent Document 1 proposes a technology for imparting high molding accuracy to a stereolithography resin composition, which enables low viscosity by blending N-acryloylmorpholine with a urethane acrylate compound having a specific structure. Furthermore, Patent Document 2 proposes a technology for imparting strength and toughness by blending inorganic particles of a specific shape. Meanwhile, Patent Document 3 proposes a technology that blends a urethane acrylate compound of a specific structure with an inorganic filler of a specific particle size, and Patent Document 4 proposes a technology that blends a urethane acrylate compound with an ultraviolet absorbing filler.

Japanese Patent Application Laid-Open No. 7-140651 Japanese Patent Application Laid-Open No. 8-183821 JP 2015-43793 A International Publication No. 2018/074380

The stereolithography resin composition described in Patent Document 1 does not specifically describe the mechanical properties of the object formed therefrom. In addition, the stereolithography resin compositions described in Patent Documents 2 and 3 leave room for improvement in the modulus of elasticity of the object formed therefrom. Furthermore, the stereolithography resin compositions described in Patent Documents 1 to 4 have not been evaluated in any way for the abrasion resistance of the object formed therefrom.

Therefore, the present invention relates to a resin composition for stereolithography that has low viscosity and excellent curing properties, making it easy to mold, and can produce three-dimensional objects that have high strength, high elasticity, and excellent abrasion resistance.

That is, the present invention includes the following inventions.
[1] A composition comprising a urethane-modified (meth)acrylic compound (a) having a weight average molecular weight of 1000 or less, a (meth)acrylamide compound (b), a photopolymerization initiator (c), and spherical inorganic particles (d) having an average particle size of 0.75 to 10 μm,
a content of the spherical inorganic particles (d) being 50 to 400 parts by mass per 100 parts by mass of the total amount of the urethane-modified (meth)acrylic compound (a), the (meth)acrylamide compound (b), and other polymerizable monomers, each having a weight-average molecular weight of 1,000 or less;
[2] The stereolithography resin composition according to [1], wherein the spherical inorganic particles (d) have a sphericity of 0.70 to 0.99;
[3] The stereolithography resin composition according to [1] or [2], wherein the bending strength of a molded object of the stereolithography resin composition is 120 MPa or more and the bending modulus of elasticity is 5.0 GPa or more;
[4] The stereolithography resin composition according to any one of [1] to [3], wherein the weight average molecular weight of the urethane-modified (meth)acrylic compound (a) having a weight average molecular weight of 1,000 or less is 500 or less;
[5] The stereolithography resin composition according to any one of [1] to [4], wherein the (meth)acrylamide compound (b) is a monofunctional (meth)acrylamide compound;
[6] The stereolithography resin composition according to [5], wherein the monofunctional (meth)acrylamide compound is N-acryloylmorpholine;
[7] A dental material comprising a cured product of the stereolithography resin composition according to any one of [1] to [6];
[8] A dental prosthesis comprising a cured product of the stereolithography resin composition according to any one of [1] to [6];
[9] A method for producing a three-dimensional object by a stereolithography method using the stereolithography resin composition according to any one of [1] to [6];
[10] The manufacturing method according to [9], wherein the optical stereolithography is a suspended liquid tank stereolithography.

The stereolithography resin composition of the present invention has low viscosity and high curing property, making it easy to mold, and can produce three-dimensional objects with high strength, high elasticity, and excellent abrasion resistance. Therefore, it can be suitably used for various dental materials, various industrial parts, and especially dental prostheses.

The resin composition for stereolithography of the present invention contains (a) a urethane-modified (meth)acrylic compound having a weight-average molecular weight of 1000 or less, (b) a (meth)acrylamide compound, (c) a photopolymerization initiator, and (d) spherical inorganic particles having an average particle size of 0.75 to 10 μm. In this specification, the upper and lower limits of the numerical ranges (contents of each component, values calculated from each component, and each physical property, etc.) can be appropriately combined. In this specification, "stereolithography" is also referred to as "optical three-dimensional modeling".

[Urethane-modified (meth)acrylic compound (a) having a weight-average molecular weight of 1,000 or less]
The urethane-modified (meth)acrylic compound (a) having a weight-average molecular weight of 1000 or less (hereinafter also simply referred to as "urethane-modified (meth)acrylic compound (a)") is used in the stereolithography resin composition of the present invention to improve the strength, elasticity, molding accuracy and abrasion resistance of an object molded from the stereolithography resin composition. Examples of the urethane-modified (meth)acrylic compound (a) having a weight-average molecular weight of 1000 or less include urethane-modified (meth)acrylic compounds that do not contain a polymer structure and urethane-modified (meth)acrylic compounds that contain a polymer structure.

The urethane-modified (meth)acrylic compound (a) can be easily synthesized, for example, by addition reaction of a compound containing an isocyanate having an alkylene skeleton or a phenylene skeleton with a (meth)acrylic compound having a hydroxyl group (-OH). On the other hand, when the urethane-modified (meth)acrylic compound (a) having a weight average molecular weight of 1000 or less is a urethane-modified (meth)acrylic compound containing a polymer structure, the weight average molecular weight must be 1000 or less from the viewpoint of excellent strength. In addition, when the urethane-modified (meth)acrylic compound (a) does not contain a polymer structure, there is no concept of weight average molecular weight, so the molecular weight is applied instead of the weight average molecular weight. When the weight average molecular weight exceeds 1000, the molded object tends to have low elasticity. From the viewpoint of strength and elastic modulus, the weight average molecular weight is preferably 750 or less, more preferably 700 or less, and even more preferably 500 or less. Furthermore, it is preferable that the compound does not contain a polymer structure such as polyester, polycarbonate, polyurethane, polyether, etc., and when these structures are contained, the molded object tends to have low elasticity. In particular, from the viewpoint of water resistance, it is more preferable that the number of urethane bonds in one molecule is 3 or less, and even more preferable that the number is 2 or less. Note that the weight average molecular weight in this invention means the weight average molecular weight calculated in terms of polystyrene as determined by gel permeation chromatography (GPC).

Examples of compounds having an isocyanate group include methylene diisocyanate (MDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), trimethylhexamethylene diisocyanate (TMHMDI), tricyclodecane diisocyanate (TCDDI), adamantane diisocyanate (ADI), tolylene diisocyanate (TDI), xylylene diisocyanate (XDI), and diphenylmethane diisocyanate (MDI). These may be used alone or in combination of two or more. Among these, from the viewpoint of increasing the strength and elasticity of the object molded from the stereolithography resin composition of the present invention, HDI, IPDI, TMHMDI, and TCDDI are preferred, and IPDI and TMHMDI are more preferred.

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, N-hydroxyethyl (meth)acrylamide, N,N-bis(2-hydroxyethyl) (meth)acrylamide, 2-hydroxy hydroxy(meth)acrylate compounds such as 1,2-bis[4-[3-(meth)acryloyloxy-2-hydroxypropoxy]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. These may be used alone or in combination of two or more. Among these, from the viewpoint of excellent curing properties of the stereolithography resin composition of the present invention, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxy-3-acryloyloxypropyl (meth)acrylate, and N-hydroxyethyl (meth)acrylamide are preferred, and 2-hydroxyethyl (meth)acrylate is more preferred.

The addition reaction between a compound having an isocyanate group and a (meth)acrylic compound having a hydroxyl group can be carried out according to a known method, and there are no particular limitations.

Examples of urethane-modified (meth)acrylic compounds (a) that do not contain a polymer structure include bifunctional or higher urethane-modified (meth)acrylic compounds such as 2,2,4-trimethylhexamethylenebis(2-carbamoyloxyethyl)dimethacrylate (commonly known as UDMA), 2,4-tolylenebis(2-carbamoyloxyethyl)dimethacrylate, bishydroxyethylmethacrylate-isophoronediurethane, 2,4-tolylenebis(2-carbamoyloxyethyl)dimethacrylate, N,N'-(2,2,4-trimethylhexamethylene)bis[2-(aminocarboxy)propane-1,3-diol]tetramethacrylate, hexamethylenebis{2-carbamoyloxy-3-phenoxypropyl}diacrylate, and 2,4-tolylenebis(2-carbamoyloxyethyl)hexaacrylate. These may be used alone or in combination of two or more. Among these, from the viewpoint of strength and elasticity, 2,2,4-trimethylhexamethylene bis(2-carbamoyloxyethyl) dimethacrylate and N,N'-(2,2,4-trimethylhexamethylene) bis[2-(aminocarboxy)propane-1,3-diol]tetramethacrylate are preferred, and 2,2,4-trimethylhexamethylene bis(2-carbamoyloxyethyl) dimethacrylate is more preferred.

The content of the urethane-modified (meth)acrylic compound (a) in the stereolithography resin composition of the present invention is preferably 10 to 99 parts by mass per 100 parts by mass of the total amount of the urethane-modified (meth)acrylic compound (a), the (meth)acrylamide compound (b) and other polymerizable monomers, and from the viewpoint of superior curability, strength of the molded object, molding precision and abrasion resistance, it is more preferably 30 to 90 parts by mass, and even more preferably 50 to 80 parts by mass.

[(Meth)acrylamide compound (b)]
The (meth)acrylamide compound (b) is used in the stereolithography resin composition of the present invention to reduce the viscosity of the stereolithography resin composition and to impart curability and abrasion resistance. Furthermore, in the present invention, relatively large inorganic particles are blended for the purpose of high strength and high elasticity, but when a filler with a large particle size and a spherical shape is blended, the filler tends to fall off, and the abrasion resistance decreases. However, (meth)acrylamide (b) is copolymerized with urethane-modified (meth)acrylic compound (a) to give a cured product that is strong and has a strong interaction with the filler, and therefore, it is presumed that a cured product with excellent abrasion resistance can be obtained by increasing the strength and elasticity while suppressing the fall-off of the filler.

Examples of (meth)acrylamide compounds (b) include monofunctional (meth)acrylamide compounds such as N-acryloylmorpholine, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-di-n-propyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N,N-di-n-butyl(meth)acrylamide, N,N-di-n-hexyl(meth)acrylamide, N,N-di-n-octyl(meth)acrylamide, N,N-di-2-ethylhexyl(meth)acrylamide, N-(2-hydroxyethyl)(meth)acrylamide, and N,N-bis(2-hydroxyethyl)(meth)acrylamide. These may be used alone or in combination of two or more. Among these, N-acryloylmorpholine, N,N-dimethyl(meth)acrylamide, and N,N-diethyl(meth)acrylamide are more preferred, and N-acryloylmorpholine is even more preferred, because they have good miscibility with the urethane-modified (meth)acrylic compound (a), and have excellent curability of the stereolithography resin composition and abrasion resistance of the cured product.

The content of (meth)acrylamide compound (b) is preferably 5 to 80 parts by mass per 100 parts by mass of the total amount of urethane-type (meth)acrylic compound (a), (meth)acrylamide compound (b) and other polymerizable monomers, and is more preferably 10 to 60 parts by mass, and even more preferably 15 to 40 parts by mass, in terms of superior curability, strength of the molded product, molding precision and abrasion resistance.

The stereolithography resin composition of the present invention may contain other polymerizable monomers (hereinafter simply referred to as "other polymerizable monomers") other than the urethane-modified (meth)acrylic compound (a) and the (meth)acrylamide compound (b) having a weight-average molecular weight of 1000 or less.

As the other polymerizable monomer, a radical polymerizable monomer is preferably used. Specific examples of radical polymerizable monomers include (meth)acrylate-based polymerizable monomers; esters such as α-cyanoacrylic acid, (meth)acrylic acid, α-halogenated acrylic acid, crotonic acid, cinnamic acid, sorbic acid, maleic acid, and itaconic acid; vinyl esters; vinyl ethers; mono-N-vinyl derivatives; and styrene derivatives. Among these, (meth)acrylate-based polymerizable monomers are preferred from the viewpoint of curability. These may be used alone or in combination of two or more.

(Meth)acrylate polymerizable monomers include monofunctional polymerizable monomers having one polymerizable group, and polyfunctional polymerizable monomers having multiple polymerizable groups.

Monofunctional (meth)acrylate polymerizable monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, propylene glycol mono(meth)acrylate, glycerol mono(meth)acrylate, erythritol mono(meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, ) acrylate, sec-butyl (meth)acrylate, t-butyl (meth)acrylate, isobutyl (meth)acrylate, n-hexyl (meth)acrylate, cyclohexyl (meth)acrylate, lauryl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, isobornyl (meth)acrylate, benzyl (meth)acrylate, phenyl (meth)acrylate, 2,3-dibromopropyl (meth)acrylate, 3-(meth)acryloyloxypropyltrimethoxysilane, 11-(meth)acryloyloxyundecyltrimethoxysilane, (meth)acrylamide, etc.

Examples of polyfunctional polymerizable monomers include bifunctional polymerizable monomers of aromatic compounds, bifunctional polymerizable monomers of aliphatic compounds, and trifunctional or higher polymerizable monomers.

Examples of aromatic bifunctional polymerizable monomers include 2,2-bis((meth)acryloyloxyphenyl)propane, 2,2-bis[4-(3-acryloyloxy-2-hydroxypropoxy)phenyl]propane, 2,2-bis[4-(3-methacryloyloxy-2-hydroxypropoxy)phenyl]propane (commonly known as "Bis-GMA"), 2,2-bis(4-(meth)acryloyloxyethoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxypolyethoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxydiethoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxytetraethoxyphenyl)propane, and 2,2-bis(4-(meth)acryloyloxypentaethoxyphenyl)propane. , 2,2-bis(4-(meth)acryloyloxydipropoxyphenyl)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)acryloyloxypropoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxyisopropoxyphenyl)propane, 1,4-bis(2-(meth)acryloyloxyethyl)pyromellitate, and the like. These may be used alone or in combination of two or more. Among these, 2,2-bis[4-(3-methacryloyloxy-2-hydroxypropoxy)phenyl]propane and 2,2-bis(4-(meth)acryloyloxypolyethoxyphenyl)propane are preferred due to their excellent curability and strength of the cured product. Among 2,2-bis(4-(meth)acryloyloxypolyethoxyphenyl)propane, 2,2-bis(4-methacryloyloxypolyethoxyphenyl)propane (a compound with an average number of moles of ethoxy groups added of 2.6 (commonly known as "D-2.6E")) is preferred.

Examples of aliphatic compound-based bifunctional polymerizable monomers include 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, 1,2-bis(3-methacryloyloxy-2-hydroxypropoxy)ethane, and the like. Among these, triethylene glycol dimethacrylate is preferred because of its excellent curability and strength of the cured product. These may be used alone or in combination of two or more.

Examples of trifunctional or higher polymerizable monomers 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, N,N'-(2,2,4-trimethylhexamethylene)bis[2-(aminocarboxy)propane-1,3-diol]tetra(meth)acrylate, 1,7-diacryloyloxy-2,2,6,6-tetra(meth)acryloyloxymethyl-4-oxaheptane, etc. Among these, N,N'-(2,2,4-trimethylhexamethylene)bis[2-(aminocarboxy)propane-1,3-diol]tetramethacrylate and 1,7-diacryloyloxy-2,2,6,6-tetraacryloyloxymethyl-4-oxaheptane are preferred due to their excellent curability and strength of the cured product.

[Photopolymerization initiator (c)]
The photopolymerization initiator (c) used in the present invention can be selected from photopolymerization initiators used in general industrial fields, and among them, photopolymerization initiators used for dental purposes are preferably used.

Examples of photopolymerization initiators (c) include (bis)acylphosphine oxides, thioxanthones or quaternary ammonium salts of thioxanthones, ketals, α-diketones, coumarins, anthraquinones, benzoin alkyl ether compounds, α-aminoketone compounds, etc. These may be used alone or in combination of two or more.

Among these photopolymerization initiators (c), it is preferable to use at least one selected from the group consisting of (bis)acylphosphine oxides and their salts, and α-diketones. This results in a stereolithography resin composition that has excellent photocurability in the ultraviolet and visible light regions and exhibits sufficient photocurability when using any light source, such as a laser such as an Ar laser or a He-Cd laser; or lighting such as a halogen lamp, a xenon lamp, a metal halide lamp, a light-emitting diode (LED), a mercury lamp, or a fluorescent lamp.

Among the (bis)acylphosphine oxides used as the photopolymerization initiator (c), 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-trimethylbenzoyldiphenylphosphine oxide potassium salt, and 2,4,6-trimethylbenzoyldiphenylphosphine oxide ammonium salt. 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. Further examples include compounds described in JP-A-2000-159621.

Among these (bis)acylphosphine oxides, 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 are particularly preferred.

Examples of α-diketones used as the photopolymerization initiator (c) include diacetyl, benzil, camphorquinone, 2,3-pentadione, 2,3-octadione, 9,10-phenanthrenequinone, 4,4'-oxybenzil, and acenaphthenequinone. Among these, camphorquinone is particularly preferred when using a light source in the visible light region.

From the viewpoint of the curability of the resulting stereolithography resin composition, the content of the photopolymerization initiator (c) in the stereolithography resin composition of the present invention is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 7.5 parts by mass, and even more preferably 1.0 to 5.0 parts by mass, per 100 parts by mass of the total of the urethane-modified (meth)acrylic compound (a), the (meth)acrylamide compound (b), and other polymerizable monomers. If the content of the photopolymerization initiator (c) exceeds 10 parts by mass per 100 parts by mass of the total of the urethane-modified (meth)acrylic compound (a), the (meth)acrylamide compound (b), and other polymerizable monomers, and if the solubility of the photopolymerization initiator itself is low, precipitation from the stereolithography resin composition may occur.

[Spherical inorganic particles (d)]
The spherical inorganic particles (d) are used in the stereolithography resin composition of the present invention in a specific content to increase the elasticity without impairing the moldability. That is, when the spherical inorganic particles (d) are spherical, the frictional resistance or interaction between the particles is reduced when shear stress is applied to the stereolithography resin composition, and the stereolithography resin composition has a low viscosity, resulting in excellent moldability. In addition, by making the particle size specific, the particles are densely packed while suppressing an increase in viscosity, so that the rigidity of the inorganic particles is expressed in the molded object and the elasticity is increased. However, when the particle size of the inorganic particles is too small, the interaction between the particles is increased, and not only the viscosity is increased, but also the rigidity of the inorganic particles is difficult to be expressed. On the other hand, when the particle size of the inorganic particles is too large, the composition is difficult to be densely packed and becomes non-uniform, so that the elasticity is difficult to be increased. In addition, the spherical inorganic particles (d) impart abrasion resistance to the cured product of the stereolithography resin composition.

Examples of the spherical inorganic particles (d) used in the present invention include quartz, silica, titanium oxide, zirconium oxide (zirconia), zinc oxide, cerium oxide, aluminum oxide (alumina), silica-titania, silica-titania-barium oxide, silica-zirconia, silica-alumina, aluminosilicate 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. Among these, quartz, silica, alumina, zirconia, barium glass, and fluoroaluminosilicate glass are preferably used, more preferably silica and barium glass, and even more preferably silica, in terms of the excellent elastic modulus of the cured product of the stereolithography resin composition obtained.

From the viewpoint of the modeling property of the photo-molding resin composition and the mechanical properties of the cured product, the average particle diameter of the spherical inorganic particles (d) must be 0.75 to 10 μm, preferably 0.8 to 5.0 μm, more preferably 0.85 to 2.5 μm, and even more preferably 0.9 to 2.0 μm. If the average particle diameter of the spherical inorganic particles (d) is less than 0.75 μm, the viscosity of the photo-molding resin composition tends to increase and the molding accuracy tends to decrease, and the elastic modulus of the cured product of the photo-molding resin composition tends to decrease, and the resin (polymer) contained in the photo-molding resin composition tends to be strongly influenced and the abrasion resistance tends to decrease. On the other hand, if the average particle diameter of the spherical inorganic particles (d) is greater than 10 μm, the irradiated light tends to be scattered, so the molding accuracy tends to decrease, and the inorganic particles tend to fall off first due to the force of abrasion, and the abrasion resistance of the cured product of the photo-molding resin composition tends to decrease. In one preferred embodiment, the stereolithography resin composition contains a urethane-modified (meth)acrylic compound (a), a (meth)acrylamide compound (b), a photopolymerization initiator (c), and spherical inorganic particles (d) having an average particle size of 0.75 to 10 μm, but does not contain inorganic particles having an average particle size of less than 0.75 μm. In another preferred embodiment, the stereolithography resin composition does not contain inorganic fiber whiskers as inorganic particles.

The average particle size of the spherical inorganic particles (d) is the average primary particle size, and can be determined by a laser diffraction scattering method. The laser diffraction scattering method can be performed, for example, by a laser diffraction particle size distribution measuring device (SALD-2300: manufactured by Shimadzu Corporation) using a 0.2% aqueous solution of sodium hexametaphosphate as a dispersion medium, and can be measured on a volume basis.

The shape of the spherical inorganic particles (d) must be spherical in order to provide excellent fluidity. The sphericity of the spherical inorganic particles (d) is preferably 0.70 to 0.99, more preferably 0.80 to 0.99, and even more preferably 0.90 to 0.99.

The shape of the spherical inorganic particles (d) can be measured from images taken by a scanning electron microscope (hereinafter referred to as SEM). The average particle size and sphericity can be determined by processing SEM photographs with an image analyzer. The number of samples to be image-processed is 200 or more, and the average value is used. The "sphericity" defined here is substituted for the circularity determined by image processing of the SEM image. The circularity is expressed by the following formula. Circularity=1 represents a perfect circle.
Circularity=(4·π·S)/(L ² )
(In the formula, S represents the area of the particle obtained by image processing, and L represents the perimeter of the particle.)
The particle diameter used to calculate the circularity was determined as the circle equivalent diameter (diameter when assumed to be a perfect circle)=(4·S/π) ^1/2 .

The content of the spherical inorganic particles (d) in the stereolithography resin composition of the present invention must be 50 to 400 parts by mass, preferably 75 to 300 parts by mass, and more preferably 100 to 200 parts by mass, per 100 parts by mass of the total amount of the urethane-modified (meth)acrylic compound (a), the (meth)acrylamide compound (b) and other polymerizable monomers, from the viewpoints of the consistency of the resulting stereolithography resin composition, the molding accuracy and the mechanical properties of the cured product. If the content of the spherical inorganic particles (d) is less than 50 parts by mass, sufficient mechanical properties cannot be obtained in the three-dimensional object. On the other hand, if the content of the spherical inorganic particles (d) exceeds 400 parts by mass, the viscosity of the stereolithography resin composition increases, making it difficult to mold the object.

In order to adjust the miscibility with the total amount of 100 parts by mass of the urethane-modified (meth)acrylic compound (a), the (meth)acrylamide compound (b) and other polymerizable monomers, it is preferable to preliminarily surface-treat the spherical inorganic particles (d) with a known surface treatment agent such as an organic compound containing an acidic group; a fatty acid amide such as a saturated fatty acid amide, an unsaturated fatty acid amide, a saturated fatty acid bisamide, an unsaturated fatty acid bisamide; or an organic silicon compound such as a silane coupling agent. In order to increase the chemical bonding between the urethane-modified (meth)acrylic compound (a), the (meth)acrylamide compound (b) and other polymerizable monomers and the spherical inorganic particles (d) to improve the strength and abrasion resistance of the cured product, it is preferable to surface-treat the spherical inorganic particles (d) with an organic compound containing an acidic group. Examples of the acidic group-containing organic compound include organic compounds having at least one acidic group such as a phosphoric acid group, a pyrophosphoric acid group, a thiophosphoric acid group, a phosphonic acid group, a sulfonic acid group, or a carboxylic acid group, and an organic compound having at least one phosphoric acid group is preferable. When two or more types of surface treatment agents are used, the surface treatment agent layer may be a mixture of two or more types of surface treatment agents, or a multi-layer structure in which multiple surface treatment agent layers are laminated may be used.

Examples of acidic group-containing organic compounds that contain phosphoric acid groups include 2-ethylhexyl acid phosphate, stearyl acid phosphate, 2-(meth)acryloyloxyethyl dihydrogen phosphate, 3-(meth)acryloyloxypropyl dihydrogen phosphate, 4-(meth)acryloyloxybutyl dihydrogen phosphate, 5-(meth)acryloyloxypentyl dihydrogen phosphate, 6-(meth)acryloyloxyhexyl dihydrogen phosphate, 7- (Meth)acryloyloxyheptyl dihydrogen phosphate, 8-(meth)acryloyloxyoctyl dihydrogen phosphate, 9-(meth)acryloyloxynonyl dihydrogen phosphate, 10-(meth)acryloyloxydecyl dihydrogen phosphate, 11-(meth)acryloyloxyundecyl dihydrogen phosphate, 12-(meth)acryloyloxydodecyl dihydrogen phosphate, 16-(meth)acryloyloxyhexadecyl dihydrogen phosphate dihydrogen phosphate, 20-(meth)acryloyloxyicosyl dihydrogen phosphate, bis[2-(meth)acryloyloxyethyl]hydrogen phosphate, bis[4-(meth)acryloyloxybutyl]hydrogen phosphate, bis[6-(meth)acryloyloxyhexyl]hydrogen phosphate, bis[8-(meth)acryloyloxyoctyl]hydrogen phosphate, bis[9-(meth)acryloyloxynonyl]hydrogen phosphate, bis[1 Examples include bis[2-(meth)acryloyloxydecyl]hydrogen phosphate, 1,3-di(meth)acryloyloxypropyl dihydrogen phosphate, 2-(meth)acryloyloxyethylphenyl hydrogen phosphate, 2-(meth)acryloyloxyethyl-2-bromoethyl hydrogen phosphate, bis[2-(meth)acryloyloxy-(1-hydroxymethyl)ethyl]hydrogen phosphate, and their acid chlorides, alkali metal salts, and ammonium salts.

As an acidic group-containing organic compound having an acidic group such as a pyrophosphate group, a thiophosphate group, a phosphonate group, a sulfonic acid group, or a carboxylic acid group, for example, those described in International Publication No. 2012/042911 can be suitably used.

Examples of saturated fatty acid amides include palmitic acid amide, stearic acid amide, and behenic acid amide. Examples of unsaturated fatty acid amides include oleic acid amide and erucic acid amide. Examples of saturated fatty acid bisamides include ethylene bispalmitic acid amide, ethylene bisstearic acid amide, and hexamethylene bisstearic acid amide. Examples of unsaturated fatty acid bisamides include ethylene bisoleic acid amide, hexamethylene bisoleic acid amide, and N,N'-dioleylsebacic acid amide.

An example of the organosilicon compound is a compound represented by R ¹ _n SiX _4-n , where R ¹ is a substituted or unsubstituted hydrocarbon group having 1 to 12 carbon atoms, X is an alkoxy group having 1 to 4 carbon atoms, a hydroxyl group, a halogen atom or a hydrogen atom, and n is an integer from 0 to 3, and when there are multiple R ^1s and multiple Xs, they may be the same or different.

Specific examples include methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, isobutyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(β-methoxyethoxy)silane, 3,3,3-trifluoropropyltrimethoxysilane, methyl-3,3,3-trifluoropropyldimethoxysilane, and β-(3,4-epoxycyclohexyl)ethyl Trimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-methacryloyloxypropylmethyldimethoxysilane, γ-methacryloyloxypropylmethyldiethoxysilane, N-β(aminoethyl)γ-aminopropylmethyldimethoxysilane, N-β(aminoethyl)γ-aminopropyltrimethoxysilane, N-β(aminoethyl)γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane silane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, trimethylsilanol, methyltrichlorosilane, methyldichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, vinyltrichlorosilane, trimethylbromosilane, diethylsilane, vinyltriacetoxysilane, ω-(meth)acryloyloxyalkyltrimethoxysilane [number of carbon atoms between the (meth)acryloyloxy group and the silicon atom: 3 to 12, e.g., γ-methacryloyloxyalkyltrimethoxysilane, Examples of such silanes include ω-(meth)acryloyloxyalkyltriethoxysilane [number of carbon atoms between the (meth)acryloyloxy group and the silicon atom: 3 to 12, e.g., γ-methacryloyloxypropyltriethoxysilane], hexaethyldisilazane, hexa-n-propyldisilazane, hexaisopropyldisilazane, 1,1,2,2-tetramethyl-3,3-diethyldisilazane, 1,1,3,3-tetramethyldisilazane, 1,1,1,3,3,3-hexamethyldisilazane, and 1,1,1,3,3-pentamethyldisilazane.

Among these, silane coupling agents having a functional group capable of copolymerizing with a polymerizable monomer, such as ω-(meth)acryloyloxyalkyltrimethoxysilane [number of carbon atoms between the (meth)acryloyloxy group and the silicon atom: 3 to 12], ω-(meth)acryloyloxyalkyltriethoxysilane [number of carbon atoms between the (meth)acryloyloxy group and the silicon atom: 3 to 12], vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, γ-glycidoxypropyltrimethoxysilane, etc. are preferred.

The surface treatment method can be any known method without any particular limitation, and examples of such methods include a method in which the surface treatment agent is sprayed onto the spherical inorganic particles (d) while vigorously stirring the particles, and a method in which the spherical inorganic particles (d) and the surface treatment agent are dispersed or dissolved in a suitable solvent, and then the solvent is removed.

The amount of the surface treatment agent used is not particularly limited, and is preferably, for example, 0.1 to 50 parts by mass per 100 parts by mass of the spherical inorganic particles (d).

The stereolithography resin composition of the present invention may contain a known stabilizer to suppress deterioration or adjust photocurability. Examples of the stabilizer include polymerization inhibitors, ultraviolet absorbers, antioxidants, chelating agents, and pH adjusters. One type of stabilizer may be used alone, or two or more types may be used in combination.

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 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 urethane-modified (meth)acrylic compound (a), the (meth)acrylamide compound (b), and other polymerizable monomers.

In addition, known additives can be blended into the stereolithography resin composition of the present invention for the purpose of adjusting the color tone or the paste properties. Examples of the additives include colorants (pigments, dyes), organic solvents, thickeners, surfactants, etc. Additives may be used alone or in combination of two or more. Examples of pigments include inorganic pigments and organic pigments. Examples of inorganic pigments include carbon blacks (C.I. Pigment Black 7) such as furnace black, lamp black, acetylene black, and channel black, and iron oxide. Examples of organic pigments include azo pigments such as insoluble azo pigments, condensed azo pigments, azo lakes, and chelate azo pigments; polycyclic pigments such as phthalocyanine pigments, perylene and perinone pigments, anthraquinone pigments, quinacridone pigments, dioxane pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone pigments; dye chelates (e.g., basic dye chelates, acid dye chelates, etc.); dye lakes (basic dye lakes, acid dye lakes); nitro pigments; nitroso pigments; aniline black; and daylight fluorescent pigments. The pigment may be an ultrafine particle having an average primary particle size of less than 0.10 μm.

The stereolithography resin composition of the present invention has low viscosity and is easy to mold, and the cured product has high strength, high elasticity, and excellent abrasion resistance. Therefore, the stereolithography resin composition of the present invention can be used in applications that utilize these advantages, for example, for various three-dimensional objects manufactured by optical three-dimensional modeling methods. In particular, it can be used favorably for dental materials and industrial parts, and is particularly suitable for dental prostheses.

Another embodiment of the present invention is a method for producing a three-dimensional object by a conventionally known optical three-dimensional modeling method (e.g., a suspended liquid tank stereolithography method) using any of the above-mentioned stereolithography resin compositions.

When performing a conventionally known optical three-dimensional modeling method (e.g., a suspended liquid tank stereolithography method) using the stereolithography resin composition of the present invention, any conventionally known optical three-dimensional modeling method and device (e.g., a stereolithography machine such as DIGITALWAX (registered trademark) 028J-Plus manufactured by DWS) can be used. Among them, in the present invention, it is preferable to use active energy rays as the light energy for curing the resin. In the present invention, "active energy rays" refers to energy rays that can cure 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 410 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 using a laser as the light source, it is possible to increase the energy level and shorten the modeling time, and by taking advantage of the excellent focusing properties of the laser beam, it is possible to obtain a three-dimensional object with high modeling accuracy.

As described above, when performing optical three-dimensional modeling using the stereolithography resin composition of the present invention, any of the conventionally known methods (e.g., suspended liquid tank stereolithography) and conventionally known stereolithography system devices can be used without any particular limitations. A representative example of an optical three-dimensional modeling method preferably used in the present invention is a method in which a stereolithography resin composition is selectively irradiated with active energy rays to form a cured layer so as to obtain a cured layer having a desired pattern, and then an uncured liquid stereolithography resin composition is further supplied to the cured layer, and similarly irradiated with active energy rays to form a new cured layer continuous with the cured layer, and the steps are repeated to finally obtain the desired three-dimensional object. The three-dimensional object obtained by this method may be used as it is, or, in some cases, may be used after further post-curing by irradiation with light or post-curing by heat to further improve its mechanical properties or shape stability.

The present invention includes embodiments that combine the above configurations in various ways within the scope of the technical concept of the present invention, as long as the effects of the present invention are achieved.

Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to these examples in any way, and many modifications within the scope of the technical concept of the present invention are possible by those with ordinary knowledge in this field. Each component used in the stereolithography resin composition according to the examples or comparative examples is explained below together with its abbreviation.

[Urethanized (meth)acrylic compound (a) having a weight average molecular weight of 1,000 or less]
UDMA: 2,2,4-trimethylhexamethylenebis(2-carbamoyloxyethyl)dimethacrylate (manufactured by Kyoeisha Chemical Co., Ltd., molecular weight: 471)
U4TH: N,N'-(2,2,4-trimethylhexamethylene)bis[2-(aminocarboxy)propane-1,3-diol]tetramethacrylate (manufactured by Kyoeisha Chemical Co., Ltd., molecular weight: 673)

[(Meth)acrylamide compound (b)]
ACMO: N-acryloylmorpholine (KJ Chemicals Co., Ltd.)
DEAA: N,N-diethylacrylamide (KJ Chemicals Co., Ltd.)

[Photopolymerization initiator (c)]
TPO: 2,4,6-trimethylbenzoyldiphenylphosphine oxide BAPO: bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide

[Spherical inorganic particles (d) having an average particle size of 0.75 to 10 μm]
Spherical inorganic particles (d)-1: γ-methacryloyloxypropyltrimethoxysilane-treated silica (product name "ADMAFINE (registered trademark) SO-C4", manufactured by Admatechs Co., Ltd., average particle size: 1.0 μm, sphericity: 0.96)
Spherical inorganic particles (d)-2: γ-methacryloyloxypropyltrimethoxysilane-treated silica (product name "ADMAFINE (registered trademark) SO-C6", manufactured by Admatechs Co., Ltd., average particle size: 2.0 μm, sphericity: 0.97)

[Other polymerizable monomers]
Bis-GMA: 2,2-bis[4-(3-methacryloyloxy-2-hydroxypropoxy)phenyl]propane (manufactured by Shin-Nakamura Chemical Co., Ltd.)
TEGDMA: Triethylene glycol dimethacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.)

[Stabilizer]
BHT: 3,5-di-t-butyl-4-hydroxytoluene

(Examples 1 to 7 and Comparative Examples 1 to 5)
The components shown in Tables 1 and 2 were mixed at room temperature (20°C ± 15°C, JIS (Japanese Industrial Standards) Z 8703:1983) in the amounts shown in Tables 1 and 2 to prepare inks as stereolithography resin compositions according to Examples 1 to 7 and Comparative Examples 1 to 5.

<Formability>
1. Possibility of modeling For the inks of each Example and Comparative Example, a stereolithography machine (DIGITALWAX (registered trademark) 020D manufactured by DWS) was used to manufacture a cubic three-dimensional object with a side length of 10.000 mm at a modeling pitch of 50 μm and a laser scanning speed of 4300 mm/sec. The stereolithography machine was equipped with a tray and a base whose surface was treated with a coating material. The three-dimensional object being modeled did not fall off the base equipped with the stereolithography machine, the modeling was interrupted, the container was destroyed (damage to the coating material of the tray filled with the resin composition), etc., and it was visually observed whether it was possible to model (n = 5). If even one of them could not be modeled, it was marked as "not possible to model".
2. Fluidity A PET film having a square base with a side length of 50 mm and a thickness of 0.05 mm was placed on a flat surface, and 0.5 ml of the ink of each Example and Comparative Example was dropped at the center of the film, and the film was left to stand for 10 minutes in a thermostatic chamber at 25°C. Next, the maximum diameter (long diameter) and the minimum diameter (short diameter) of the ink that spread in a circle were averaged to calculate the diameter of the ink. For each Example and Comparative Example, three samples were measured by this method to calculate the diameter of the ink (n=3). The average of the calculated values is shown in Tables 1 and 2. Furthermore, the average value of the three measurements was taken as the measured value of fluidity. The greater the fluidity, the easier the ink flows and the better the shape. In this test, a viscosity of 30 mm or more has high fluidity and excellent shapeability, and a viscosity of 40 mm or more is more preferable.
3. Molding accuracy For the inks of each Example and Comparative Example, a stereolithography machine (DIGITALWAX (registered trademark) 020D manufactured by DWS) was used to manufacture a cubic three-dimensional object with a side length of 10.000 mm at a modeling pitch of 50 μm and a laser scanning speed of 4300 mm/sec. The obtained three-dimensional object was washed with ethanol to remove unpolymerized polymerizable monomer, and then the dimensions (unit: mm) were measured using a micrometer, and the molding error for molding accuracy was calculated using the following formula (n=5). The average values of the measured values are shown in Tables 1 and 2. When the molding error is 1.0% or less, the molding accuracy is excellent, and when a crown or bridge is molded in dental applications, it is likely to be excellent in compatibility, and a molding error of 0.80% or less is preferable.

<Flexural strength and flexural modulus>
For the compositions described in Tables 1 and 2 of each Example and Comparative Example, a rectangular parallelepiped object having a length of 25.0 mm, width of 2.0 mm, and thickness of 2.0 mm was manufactured at a modeling pitch of 50 μm and a laser scanning speed of 4300 mm/sec using a stereolithography machine (DIGITALWAX (registered trademark) 028J-Plus manufactured by DWS). The obtained object was washed with methanol to remove unpolymerized polymerizable monomer, and then polymerized by a light irradiation machine (Otoflash (registered trademark) G171 manufactured by EnvisionTEC) to obtain a cured product. The obtained cured product was polished with silicon carbide paper No. 300, and then the bending strength (three-point bending strength) and bending modulus were measured using a precision universal testing machine (manufactured by Shimadzu Corporation, product name "AG-I 100N") at a support distance of 20 mm and a crosshead speed of 1 mm/min (n=5). The average values of the measured values are shown in Tables 1 and 2. A cured product having a flexural strength of 120 MPa or more and a flexural modulus of 5.0 GPa or more has excellent mechanical strength, and a cured product having a flexural strength of 140 MPa or more and a flexural modulus of 6.0 GPa or more has even better mechanical strength.

<Abrasion resistance (Taber abrasion test)>
For the compositions shown in Tables 1 and 2 of each Example and Comparative Example, a sheet-shaped object having a length of 11 cm, a width of 11 cm, and a thickness of 0.5 cm was produced using a stereolithography machine (DIGITALWAX (registered trademark) 028J-Plus manufactured by DWS) at a modeling pitch of 50 μm and a laser scanning speed of 4,300 mm/sec. The resulting object was washed with methanol to remove unpolymerized polymerizable monomer, and then subjected to drive-in polymerization using a photoirradiator (Otoflash (registered trademark) G171 manufactured by EnvisionTEC) to obtain a cured product. A circular test piece with a diameter of 10.5 cm was cut from the sheet, and the Taber abrasion amount was measured (n=2) according to JIS K 6264-2:2005 (Lambourn abrasion test) using an H-22 abrasive wheel (manufactured by TABER INDUSTRIES) as the abrasive wheel under the conditions of a load of 1 kg and 1000 revolutions. The average values of the measured values are shown in Tables 1 and ^2. If the abrasion amount in this test is 55 mm3 or less, the abrasion resistance is excellent, and if it is ⁵⁰ mm3 or less, the abrasion resistance is even better.

無機粒子１：γ－メタクリロイルオキシトリメトキシシラン処理シリカ（商品名「アドマファイン（登録商標）ＳＯ－Ｃ１」、株式会社アドマテックス製、平均粒子径：３００ｎｍ、真球度：０．９６）
無機粒子２：石英（ＭＡＲＵＷＡ ＱＵＡＲＴＺ製）をボールミルで粉砕し、平均粒子径が約２．８μｍの石英粉を得た後、この石英粉１００質量部に対して、通法により３質量部の３－メタクリロイルオキシプロピルトリメトキシシランで表面処理を行った破砕状無機粒子。
ウレタンアクリレート１：ポリエーテル系ウレタンジアクリレート（新中村化学工業株式会社製 分子量１４００）

Inorganic particle 1: γ-methacryloyloxytrimethoxysilane-treated silica (product name "ADMAFINE (registered trademark) SO-C1", manufactured by Admatechs Co., Ltd., average particle size: 300 nm, sphericity: 0.96)
Inorganic particles 2: Quartz (manufactured by Maruwa Quartz) is pulverized in a ball mill to obtain quartz powder with an average particle size of about 2.8 μm, and then 100 parts by mass of this quartz powder is surface-treated with 3 parts by mass of 3-methacryloyloxypropyltrimethoxysilane in a conventional manner to obtain crushed inorganic particles.
Urethane acrylate 1: Polyether-based urethane diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., molecular weight 1400)

As shown in Tables 1 and 2, the stereolithography resin compositions in Examples 1 to 7 had a viscosity that allowed modeling and excellent molding accuracy. In addition, the cured products had excellent bending strength, bending modulus, and abrasion resistance. The composition of Comparative Example 1 that did not contain a urethane-modified (meth)acrylic compound (A) with a weight average molecular weight of 1000 or less, and the composition of Comparative Example 5 that contained crushed inorganic particles instead of spherical inorganic particles, were not capable of modeling. The composition of Comparative Example 2 that contained a urethane-modified (meth)acrylic compound with a weight average molecular weight of more than 1000, and the composition of Comparative Example 3 that did not contain a (meth)acrylamide compound (b) had high viscosity and poor molding accuracy, and the cured products had poor bending strength, modulus, and abrasion resistance. The composition of Comparative Example 4 that contained spherical inorganic particles with an average particle size of less than 0.75 had poor abrasion resistance.

When the stereolithography resin composition of the present invention is used for stereolithography (e.g., suspended liquid tank stereolithography), it is easy to mold because of its low viscosity and excellent curing properties, and the molded objects have high strength, high elasticity, and excellent abrasion resistance, making it suitable for various dental materials and industrial parts, especially dental prostheses.

Claims (10)

The composition comprises a urethane-modified (meth)acrylic compound (a) having a weight-average molecular weight of 1000 or less, a (meth)acrylamide compound (b), a photopolymerization initiator (c), and spherical inorganic particles (d) having an average particle size of 0.75 to 10 μm,
the content of the urethane-modified (meth)acrylic compound (a) is 30 to 90 parts by mass per 100 parts by mass of the total amount of the urethane-modified (meth)acrylic compound (a), the (meth)acrylamide compound (b) and other polymerizable monomers;
the content of the (meth)acrylamide compound (b) is 10 to 60 parts by mass per 100 parts by mass of the total amount of the urethane-modified (meth)acrylamide compound (a), the (meth)acrylamide compound (b) and other polymerizable monomers,
The content of the spherical inorganic particles (d) is 50 to 400 parts by mass per 100 parts by mass of the total amount of the urethane-modified (meth)acrylic compound (a), the (meth)acrylamide compound (b), and other polymerizable monomers, each having a weight-average molecular weight of 1,000 or less. The stereolithography resin composition according to claim 1, wherein the spherical inorganic particles (d) have a sphericity of 0.70 to 0.99. The stereolithography resin composition according to claim 1 or 2, wherein the bending strength of the object molded from the stereolithography resin composition is 120 MPa or more and the bending modulus of elasticity is 5.0 GPa or more. The stereolithography resin composition according to any one of claims 1 to 3, wherein the weight average molecular weight of the urethane-modified (meth)acrylic compound (a) having a weight average molecular weight of 1000 or less is 500 or less. The stereolithography resin composition according to any one of claims 1 to 4, wherein the (meth)acrylamide compound (b) is a monofunctional (meth)acrylamide compound. The stereolithography resin composition according to claim 5, wherein the monofunctional (meth)acrylamide compound is N-acryloylmorpholine. A dental material comprising a cured product of the stereolithography resin composition according to any one of claims 1 to 6. A dental prosthesis made of a cured product of the stereolithography resin composition according to any one of claims 1 to 6. A method for producing a three-dimensional object by a photolithography method using the photolithography resin composition according to any one of claims 1 to 6. The manufacturing method according to claim 9, wherein the stereolithography is a suspended liquid tank stereolithography method.