Photocurable composition and molded article made from the same

Abstract

To provide a photocurable composition that yields a molded product with excellent mechanical properties.SOLUTION: There is provided a photocurable composition, comprising: an urethane (meth)acrylate oligomer; and as vinyl monomers, a monofunctional first monomer having a glass transition temperature (Tg1) of -100°C or more and 10°C or less; a monofunctional second monomer having a glass transition temperature (Tg2) of 70°C or more and 150°C or less; and a third monomer including a trifunctional or higher functional (meth)acrylate monomer.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a photocurable composition, and more preferably to a photocurable composition that can be suitably used for stereolithography. [Background technology]

[0002] In recent years, three-dimensional additive manufacturing devices (so-called 3D printers) have been put to practical use, which manufacture three-dimensional structures by layering and curing resin based on design data for the three-dimensional structure. Three-dimensional structures manufactured by three-dimensional additive manufacturing devices are generally known to be made of resin.

[0003] For example, Patent Document 1 discloses a rubber composition for three-dimensional additive manufacturing that contains liquid rubber, and this rubber composition can be applied to a three-dimensional additive manufacturing device to suitably produce elastic molded bodies.

[0004] Patent Document 2 describes a polymer composition for stereolithography containing a liquid polymer and a monomer, and the polymer composition for stereolithography is measured using an E-type viscometer under an environment of a temperature of 25°C and a relative humidity of 50% with a cone plate of φ25 mm and a shear rate of 100 sec -1 The present invention discloses a polymer composition for stereolithography having a viscosity of 3,000 mPa·s or less as measured under the conditions above. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2017 / 154335 [Patent Document 2] Patent Publication No. 2021-75044 Summary of the Invention [Problem to be solved by the invention]

[0006] The mechanical properties of the cured products of conventional photocurable compositions used in stereolithography are not sufficient. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a photocurable composition that provides excellent mechanical properties of molded articles. [Means for solving the problem]

[0007] The photocurable composition of the present invention comprises a urethane (meth)acrylate oligomer and As a vinyl monomer, a monofunctional first monomer having a glass transition temperature (Tg1) of -100°C or higher and 10°C or lower; a monofunctional second monomer having a glass transition temperature (Tg2) of 70°C or higher and 150°C or lower; The composition is characterized by containing a third monomer containing a tri- or higher functional (meth)acrylate monomer. [Effects of the Invention]

[0008] The photocurable composition of the present invention can be suitably used for stereolithography. The molded article formed from the photocurable composition of the present invention has excellent mechanical properties. DETAILED DESCRIPTION OF THE INVENTION

[0009] <Photocurable composition> The photocurable composition of the present invention comprises a urethane (meth)acrylate oligomer and The vinyl monomers are characterized by containing a monofunctional first monomer having a glass transition temperature (Tg1) of -100°C or higher and 10°C or lower, a monofunctional second monomer having a glass transition temperature (Tg2) of 70°C or higher and 150°C or lower, and a third monomer containing a trifunctional or higher (meth)acrylate monomer.

[0010] 1. Urethane (meth)acrylate oligomer A urethane (meth)acrylate oligomer is an oligomer having a (meth)acryloyl group and a urethane bond in the molecule. The (meth)acryloyl group is a methacryloyl group and / or an acryloyl group. An oligomer is a molecule formed by bonding multiple compounds. The oligomer is, for example, preferably a polymer formed by bonding about 3 to 100 compounds, more preferably a polymer formed by bonding about 3 to 50 compounds, and even more preferably a polymer formed by bonding about 3 to 40 compounds.

[0011] Examples of urethane (meth)acrylate oligomers include those obtained by reacting a urethane prepolymer having an isocyanate group with a (meth)acrylate monomer having a hydroxy group, those obtained by reacting a urethane prepolymer having a hydroxy group with a (meth)acrylate monomer having an isocyanate group, and those obtained by reacting a urethane prepolymer having an amino group with a (meth)acrylate monomer having an isocyanate group. In the present invention, (meth)acrylate means acrylate and / or methacrylate.

[0012] The urethane prepolymer is preferably formed by the reaction of a polyisocyanate with a polyol. A urethane bond is formed in the molecular chain of the urethane prepolymer by the reaction of the polyisocyanate with the polyol. The urethane prepolymer has an isocyanate group or a hydroxy group at the end of the molecular chain. The urethane prepolymer may also have an amino group at the end of the molecular chain.

[0013] The urethane (meth)acrylate oligomer preferably contains, as constituent components, a polyisocyanate and a polyol derived from a urethane prepolymer, and may contain, as constituent components, a polyisocyanate, a polyol, and a polyamine derived from a urethane prepolymer.

[0014] Examples of the polyol component constituting the urethane (meth)acrylate oligomer include low-molecular-weight polyols having a molecular weight of less than 500 and high-molecular-weight polyols having a number-average molecular weight of 500 or more.

[0015] Examples of the high molecular weight polyols include polyether polyols, polyester polyols, polycaprolactone polyols, polycarbonate polyols, and acrylic polyols. Examples of the polyether polyols include polyoxyethylene glycol (PEG), polyoxypropylene glycol (PPG), and polyoxytetramethylene glycol (PTMG). Examples of the polyester polyols include polyethylene adipate (PEA), polybutylene adipate (PBA), and polyhexamethylene adipate (PHMA). Examples of the polycaprolactone polyols include poly-ε-caprolactone (PCL). Examples of the polycarbonate polyols include polyhexamethylene carbonate. The high molecular weight polyols may be used alone or in combination of two or more.

[0016] The polyol component constituting the urethane (meth)acrylate oligomer preferably contains at least one selected from the group consisting of polyether diol, polyester diol, polycaprolactone diol, and polycarbonate diol.

[0017] The number average molecular weight of the polyol component constituting the urethane (meth)acrylate oligomer is preferably 300 or more, more preferably 500 or more, even more preferably 1000 or more, and is preferably 10000 or less, more preferably 8000 or less, and even more preferably 5000 or less. When the number average molecular weight of the polyol component is 300 or more, flexibility can be imparted to a molded article obtained by curing the photocurable composition. When the number average molecular weight of the polyol component is 10000 or less, hardness can be imparted to a molded article obtained by curing the photocurable composition.

[0018] The number average molecular weight of the polyol component may be measured, for example, by gel permeation chromatography (GPC) using polystyrene as a standard substance, tetrahydrofuran as an eluent, and an organic solvent GPC column (for example, "Shodex (registered trademark) KF series" manufactured by Showa Denko KK) as a column.

[0019] The polyol component may contain a low-molecular-weight polyol having a molecular weight of less than 500. Examples of the low-molecular-weight polyol include diols such as ethylene glycol, diethylene glycol, triethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, and 1,6-hexanediol; and triols such as glycerin, trimethylolpropane, and hexanetriol. The low-molecular-weight polyols may be used alone or in combination of two or more.

[0020] The polyamine that can constitute the urethane (meth)acrylate oligomer is not particularly limited as long as it has at least two amino groups. Examples of the polyamine include aliphatic polyamines such as ethylenediamine, propylenediamine, butylenediamine, and hexamethylenediamine; alicyclic polyamines such as isophoronediamine and piperazine; and aromatic polyamines.

[0021] The aromatic polyamine is not particularly limited as long as at least two or more amino groups are directly or indirectly bonded to an aromatic ring. Here, "indirectly bonded" means that the amino group is bonded to the aromatic ring via, for example, a lower alkylene group. The aromatic polyamine may be, for example, a monocyclic aromatic polyamine in which two or more amino groups are bonded to one aromatic ring, or a polycyclic aromatic polyamine containing two or more aminophenyl groups in which at least one amino group is bonded to one aromatic ring.

[0022] Examples of the monocyclic aromatic polyamines include those in which an amino group is directly bonded to an aromatic ring, such as phenylenediamine, toluenediamine, diethyltoluenediamine, and dimethylthiotoluenediamine; and those in which an amino group is bonded to an aromatic ring via a lower alkylene group, such as xylylenediamine. The polycyclic aromatic polyamines may be poly(aminobenzenes) in which at least two aminophenyl groups are directly bonded, or may be those in which at least two aminophenyl groups are bonded via a lower alkylene group or an alkylene oxide group. Among these, diaminodiphenylalkanes in which two aminophenyl groups are bonded via a lower alkylene group are preferred, and 4,4'-diaminodiphenylmethane and its derivatives are particularly preferred.

[0023] Examples of the polyisocyanate component that can constitute the urethane (meth)acrylate oligomer include compounds having at least two isocyanate groups. Examples of the polyisocyanate include aromatic polyisocyanates such as 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, a mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), 1,5-naphthylene diisocyanate (NDI), 3,3'-bitrylene-4,4'-diisocyanate (TODI), xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), and paraphenylene diisocyanate (PPDI); 4,4'-dicyclohexylmethane diisocyanate (H 12 Examples of the polyisocyanate include alicyclic polyisocyanates or aliphatic polyisocyanates such as methyl methyl diisocyanate (MDI), hydrogenated xylylene diisocyanate (H6XDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and norbornene diisocyanate (NBDI); and derivatives of these polyisocyanates. In the present invention, two or more types of polyisocyanates may be used as the polyisocyanate.

[0024] Examples of the polyisocyanate derivatives include adduct-modified products obtained by reacting diisocyanate with polyhydric alcohol; isocyanurate-modified products of diisocyanate; biuret-modified products; and allophanate-modified products, and those from which free diisocyanate has been removed are more preferred.

[0025] The adduct-modified product is a polyisocyanate obtained by reacting a diisocyanate with a polyhydric alcohol. The polyhydric alcohol is preferably a low-molecular-weight triol such as trimethylolpropane or glycerin. Preferred examples of the adduct-modified product include a triisocyanate obtained by reacting a diisocyanate with trimethylolpropane and a triisocyanate obtained by reacting a diisocyanate with glycerin.

[0026] The allophanate is, for example, a triisocyanate obtained by reacting a diisocyanate with a low molecular weight diol to form a urethane bond, and then further reacting the urethane bond with a diisocyanate.

[0027] A urethane (meth)acrylic oligomer having a (meth)acryloyl group can be obtained by reacting a urethane prepolymer having an isocyanate group at the molecular chain terminal with a (meth)acrylate having a hydroxy group. Examples of the (meth)acrylate having a hydroxy group include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.

[0028] A urethane (meth)acrylic oligomer having a (meth)acryloyl group can be obtained by reacting a urethane prepolymer having a hydroxyl or amino group at the molecular chain terminal with a (meth)acrylate having an isocyanate group. Examples of the (meth)acrylate having an isocyanate group include 2-methacryloyloxyethyl isocyanate (trade name "Karenz MOI" manufactured by Showa Denko K.K.), 2-acryloyloxyethyl isocyanate (trade name "Karenz AOI" manufactured by Showa Denko K.K.), and methacryloyloxyethyl isocyanate ethyl ether (trade name "Karenz MOIEG" manufactured by Showa Denko K.K.).

[0029] Examples of urethane (meth)acrylate oligomers include aliphatic urethane (meth)acrylate oligomers and aromatic urethane (meth)acrylate oligomers. An aliphatic urethane (meth)acrylate oligomer is one in which the component constituting the urethane (meth)acrylate oligomer is an aliphatic compound. For example, this is one in which an aliphatic polyisocyanate is the component. An aromatic urethane (meth)acrylate oligomer is one in which the component constituting the urethane (meth)acrylate oligomer is an aromatic compound. For example, this is one in which an aromatic polyisocyanate is the component. These urethane (meth)acrylate oligomers may be used alone or in combination of two or more. In order to better exhibit the effects of the present invention, it is preferable that the urethane (meth)acrylate oligomer contains an aliphatic urethane (meth)acrylate oligomer.

[0030] The glass transition temperature (Tg) of the urethane (meth)acrylate oligomer is not particularly limited, but is preferably −100° C. or higher, more preferably −90° C. or higher, even more preferably −85° C. or higher, and preferably 50° C. or lower, more preferably 10° C. or lower, even more preferably −20° C. or lower, and particularly preferably −50° C. or lower. When the glass transition temperature of the urethane (meth)acrylate oligomer is within the above range, it is possible to achieve mechanical strength while suppressing an increase in the glass transition temperature (Tg) of a molded article obtained by curing the photocurable composition.

[0031] The urethane (meth)acrylate oligomer preferably has two or more (meth)acryloyl groups in the molecule. The number of (meth)acryloyl groups in one molecule is not particularly limited, but is preferably two or more, and is preferably 10 or less, and more preferably 4 or less.

[0032] The number average molecular weight of the urethane (meth)acrylate oligomer is preferably at least 300, more preferably at least 1000, even more preferably at least 3000, and is preferably at most 30000, more preferably at most 20000, and even more preferably at most 15000. When the number average molecular weight of the urethane (meth)acrylate oligomer is within the above range, the workability in stereolithography is good, and the curing shrinkage rate and mechanical strength of a molded article obtained by curing the photocurable composition are excellent.

[0033] 2. Vinyl Monomers The photocurable composition of the present invention contains, as vinyl monomers, a monofunctional first monomer having a glass transition temperature (Tg1) of -100°C or higher and 10°C or lower, a monofunctional second monomer having a glass transition temperature (Tg2) of 70°C or higher and 150°C or lower, and a third monomer containing a trifunctional or higher functional (meth)acrylate monomer.

[0034] The vinyl monomers include a monofunctional first monomer having a glass transition temperature (Tg1) of -100°C or higher and 10°C or lower, a monofunctional second monomer having a glass transition temperature (Tg2) of 70°C or higher and 150°C or lower, and a third monomer containing a trifunctional or higher (meth)acrylate monomer, so that the molded article obtained by curing the photocurable composition has excellent mechanical properties.

[0035] In the present invention, "vinyl monomer" refers to a monomer having a radically polymerizable carbon-carbon double bond in the molecule. "Monofunctional" means having only one radically polymerizable carbon-carbon double bond in the molecule. "Trifunctional or higher" means having three or more radically polymerizable carbon-carbon double bonds in the molecule.

[0036] The first monomer is a monofunctional monomer and has only one radically polymerizable carbon-carbon double bond in the molecule.

[0037] The second monomer is a monofunctional monomer and has only one radically polymerizable carbon-carbon double bond in the molecule.

[0038] Specific examples of vinyl monomers include aromatic vinyl monomers, vinyl monomers having a hydroxy group, vinyl monomers having a carboxyl group, vinyl monomers having a sulfonic acid group, vinyl monomers having a phosphoric acid group, vinyl monomers containing a tertiary amine, vinyl monomers containing a quaternary ammonium salt group, vinyl monomers containing a heterocycle, vinylamide, vinyl monomers containing an epoxy group, vinyl carboxylate, α-olefin, dienes, (meth)acrylic monomers, etc. These vinyl monomers may be used alone or in combination of two or more.

[0039] The vinyl monomer preferably contains (meth)acrylate, since this provides a viscosity suitable for stereolithography and excellent photocuring reactivity.

[0040] Specific examples of monofunctional (meth)acrylates include ethoxylated nonylphenol acrylate, m-phenoxybenzyl acrylate, phenoxyethyl (meth)acrylate, phenoxy-2-methylethyl (meth)acrylate, phenoxyethoxyethyl (meth)acrylate, 3-phenoxy-2-hydroxypropyl (meth)acrylate, 2-phenylphenoxyethyl (meth)acrylate, 4-phenylphenoxyethyl (meth)acrylate, 3-(2-phenylphenyl)-2-hydroxypropyl (meth)acrylate, dimethylaminopropyl (meth)acrylate, (meth)acrylate of p-cumylphenol reacted with ethylene oxide, 2-bromophenoxyethyl (meth)acrylate, 2,4-dibromophenoxyethyl (meth)acrylate, 2,4,6-tribromophenoxyethyl (meth)acrylate, phenoxy (meth)acrylate modified with multiple moles of ethylene oxide or propylene oxide, isobornyl (meth)acrylate, bornyl (meth)acrylate, (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, tricyclodecanyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, cyclohexyl (meth)acrylate, 4-butylcyclohexyl (meth)acrylate, acryloylmorpholine, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate t)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, amyl (meth)acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate acrylate, undecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, butoxyethyl (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, methoxyethylene glycol (meth)acrylate, ethoxyethyl (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, diacetone (meth)acrylamide, isobutoxymethyl (meth)acrylamide, N,N-dimethyl (meth)acrylamide, t-octyl (meth)acrylamide, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, 7-amino-3,7-dimethyloctyl (meth)acrylate, N,N-diethyl (meth)acrylamide, N,N-dimethylaminopropyl (meth)acrylamide, etc.

[0041] Examples of monofunctional vinyl monomers other than (meth)acrylates include hydroxybutyl vinyl ether, lauryl vinyl ether, cetyl vinyl ether, 2-ethylhexyl vinyl ether, and vinyl monomers (such as N-vinylpyrrolidone, N-vinylcaprolactam, vinylimidazole, and vinylpyridine).

[0042] The glass transition temperature (Tg1) of the first monomer is preferably −100° C. or higher, more preferably −70° C. or higher, even more preferably −50° C. or higher, particularly preferably −20° C. or higher, and is preferably 10° C. or lower, more preferably 5° C. or lower, even more preferably 0° C. or lower, particularly preferably −5° C. or lower. The glass transition temperature (Tg1) of the first monomer is the glass transition temperature of a homopolymer of the first monomer.

[0043] Examples of the first monomer having a glass transition temperature (Tg1) of -100°C or higher and 10°C or lower include methyl acrylate (8°C), ethyl acrylate (-24°C), 2-ethylhexyl acrylate (-70°C), 2-ethylhexyl methacrylate (-10°C), isodecyl methacrylate (-41°C), n-lauryl methacrylate (-65°C), 2-hydroxyethyl acrylate (-15°C), 2-hydroxypropyl acrylate (-7°C), and the like. °C), phenoxyethyl acrylate (-22 °C), lauryl acrylate (-3 °C), isoamyl acrylate (-45 °C), butyl acrylate (-55 °C), ethyl acrylate (-24 °C), ethoxy-diethylene glycol acrylate (-70 °C), methoxy-triethylene glycol acrylate (-50 °C), (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate (-7 °C), and the like.

[0044] The glass transition temperature (Tg2) of the second monomer is preferably 70° C. or higher, more preferably 75° C. or higher, even more preferably 80° C. or higher, particularly preferably 90° C. or higher, and is preferably 150° C. or lower, more preferably 130° C. or lower, even more preferably 110° C. or lower, particularly preferably 100° C. or lower. The glass transition temperature (Tg2) of the second monomer is the glass transition temperature of a homopolymer of the second monomer.

[0045] The difference (Tg2-Tg1) between the glass transition temperature (Tg2) of the second monomer and the glass transition temperature (Tg1) of the first monomer is preferably 60°C or higher, more preferably 80°C or higher, even more preferably 90°C or higher, particularly preferably 100°C or higher, and is preferably 250°C or lower, more preferably 200°C or lower, even more preferably 150°C or lower, particularly preferably 120°C or lower.

[0046] Examples of the second monomer having a glass transition temperature (Tg2) of 70°C or higher and 150°C or lower include isobornyl acrylate (97°C), t-butyl methacrylate (107°C), methyl methacrylate (105°C), styrene (100°C), acrylic acid (106°C), and acrylonitrile (97°C).

[0047] The glass transition temperature (Tg) of the vinyl monomer can be determined from the glass transition temperatures disclosed on the following websites, for example: https: / / www.saiden-chem.co.jp / t_sekkei_ema.html https: / / www.kyoeisha.co.jp / product / kinou / lightester.php https: / / www.kyoeisha.co.jp / product / kinou / lightacrylate.php https: / / www.nitto.com / jp / ja / rd / base / adhesive / specificat /

[0048] The third monomer contains a tri- or higher functional (meth)acrylate monomer. "Tri- or higher functional (meth)acrylate monomer" refers to an acrylate monomer having three or more (meth)acryloyl groups in the molecule. The (meth)acryloyl groups are methacryloyl groups and / or acryloyl groups. By containing a tri- or higher functional (meth)acrylate monomer as the third monomer, the photocurable composition of the present invention can provide a molded product with improved mechanical properties (particularly a good balance between tensile break elongation and tensile break strength).

[0049] The third monomer preferably contains a compound represented by formula (1) or formula (2) as a trifunctional (meth)acrylate. [ka] [In formula (1), R 1 ~R 3 are the same or different and each is an alkylene group having 2 to 6 carbon atoms. 4 is a methacryloyl group or an acryloyl group. X, Y, and Z each represent an integer of 0 to 10, and the sum of X, Y, and Z is 0 to 20.]

[0050] [ka] [In formula (2), R 1 ~R 3 are the same or different and each is an alkylene group having 2 to 6 carbon atoms. 4 is a methacryloyl group or an acryloyl group. X, Y, and Z each represent an integer of 0 to 10, and the sum of X, Y, and Z is 0 to 20.]

[0051] In formula (1) and formula (2), R 1 ~R 3 Examples of the alkylene group having 2 to 6 carbon atoms represented by the formula (I) include an ethylene group, a propylene group, a butylene group, a pentylene group, and a hexylene group, and an ethylene group or a propylene group is preferred.

[0052] In formula (1) and formula (2), R 4 is a methacryloyl group (CH2=C(CH3)-C(=O)-) or an acryloyl group (CH2=CH-C(=O)-).

[0053] In formula (1) and formula (2), X, Y, and Z are the same or different and each represent an integer of 0 to 10, preferably an integer of 1 to 8. The sum of X, Y, and Z is preferably 0 to 20, more preferably 1 to 15, and even more preferably 3 to 15.

[0054] The trifunctional (meth)acrylate used in the present invention is a compound represented by the formula (1), in which X=Y=Z=0 and R 4 is a methacryloyl group or an acryloyl group, or a compound in which X=Y=Z=1 and R 1 ~R 3 is an ethylene group or a propylene group, and R 4 is preferably a methacryloyl group or an acryloyl group.

[0055] In addition, in formula (1), X = Y = Z = 0, and R 4 When R is a methacryloyl group, it is trimethylolpropane trimethacrylate, and R 4 If the group is an acryloyl group, the compound becomes trimethylolpropane triacrylate.

[0056] The trifunctional (meth)acrylate used in the present invention is a compound represented by the formula (2), in which X=Y=Z=0 and R 4 is a methacryloyl group or an acryloyl group, or a compound in which X=Y=Z=1 and R 1 ~R 3 is an ethylene group or a propylene group, and R 4 is a methacryloyl group or an acryloyl group, and X=Y=Z=1, and R 1 ~R 3 is a propylene group, and R 4 is an acryloyl group is more preferred.

[0057] In formula (2), X=Y=Z=0, and R 4 When R is a methacryloyl group, it is glyceryl trimethacrylate, and R 4 If is an acryloyl group, it becomes glyceryl triacrylate.

[0058] Specific examples of trifunctional (meth)acrylate monomers include trimethylolpropane tri(meth)acrylate, alkoxylated (e.g., ethoxylated or propoxylated) trimethylolpropane tri(meth)acrylate, glyceryl tri(meth)acrylate, alkoxylated (e.g., ethoxylated or propoxylated) glyceryl tri(meth)acrylate, pentaerythritol tri(meth)acrylate, tris(2-(meth)acryloyloxyethyl)isocyanurate, etc. These trifunctional (meth)acrylate monomers may be used alone or in combination of two or more.

[0059] In order to more effectively exert the effects of the present invention, the trifunctional (meth)acrylate monomer preferably contains an alkoxylated glyceryl tri(meth)acrylate, and more preferably contains a propoxylated glyceryl tri(meth)acrylate.

[0060] For example, in the case of propoxylated (3) glyceryl tri(meth)acrylate, the number "3" in parentheses means that the total number of oxypropylene groups in the molecule is 3 (the total number of X, Y, and Z is 3).

[0061] Examples of tetrafunctional or higher (meth)acrylates include ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, (di)pentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, pentaerythritol hexa(meth)acrylate, 1,2,3-cyclohexane tetramethacrylate, tripentaerythritol hexatriacrylate, and 1,2,4-cyclohexane tetra(meth)acrylate.

[0062] The glass transition temperature (Tg) of the homopolymer of the tri- or higher functional (meth)acrylate monomer is not particularly limited, but is preferably higher than 10° C., more preferably higher than 12° C., even more preferably higher than 15° C., and is preferably lower than 70° C., more preferably lower than 50° C., and even more preferably lower than 30° C. This is because, when the glass transition temperature of the trifunctional (meth)acrylate monomer is within the above range, the mechanical properties of the molded article obtained by curing the photocurable composition are further improved.

[0063] When the total content of the urethane (meth)acrylate oligomer and the vinyl monomer is taken as 100% by mass, the content of the urethane (meth)acrylate oligomer is preferably 30% by mass or more, more preferably 32% by mass or more, and even more preferably 35% by mass or more, and is preferably 75% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less.

[0064] When the content of the urethane (meth)acrylate oligomer is 75% by mass or less, the viscosity of the photocurable composition is not too high, making stereolithography easier. Also, when the content of the urethane (meth)acrylate oligomer is 30% by mass or more, the mechanical strength of the molded article obtained by curing the photocurable composition is not reduced.

[0065] When the total content of the urethane (meth)acrylate oligomer and the vinyl monomer is taken as 100% by mass, the content of the vinyl monomer is preferably 25% by mass or more, more preferably 40% by mass or more, even more preferably 50% by mass or more, and is preferably 70% by mass or less, more preferably 68% by mass or less, and even more preferably 65% ​​by mass or less. When the content of the vinyl monomer is within the above range, the effects of the present invention can be more effectively exhibited.

[0066] When the total content of the urethane (meth)acrylate oligomer and the vinyl monomer is taken as 100% by mass, the content of the first monomer is preferably 15% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, and preferably 60% by mass or less, more preferably 55% by mass or less, and even more preferably 50% by mass or less. If the content of the first monomer is within the above range, the glass transition temperature (Tg) of the molded article obtained by curing the photocurable composition can be lowered while maintaining mechanical strength.

[0067] When the total content of the urethane (meth)acrylate oligomer and the vinyl monomer is taken as 100% by mass, the content of the second monomer is preferably 5% by mass or more, more preferably 8% by mass or more, even more preferably 10% by mass or more, and preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less. If the content of the second monomer is within the above range, the molded article obtained by curing the photocurable composition can have sufficient mechanical strength while suppressing an increase in the glass transition temperature (Tg).

[0068] The mass ratio of the first monomer to the second monomer (first monomer / second monomer) is preferably 0.5 or more, more preferably 1.0 or more, and even more preferably 2.0 or more, and is preferably 15 or less, more preferably 10 or less, and even more preferably 5 or less. When the mass ratio (first monomer / second monomer) is within the above range, the effects of the present invention are better.

[0069] When the total content of the urethane (meth)acrylate oligomer and the vinyl monomer is taken as 100% by mass, the content of the third monomer is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 3% by mass or more, and is preferably less than 20% by mass, more preferably 18% by mass or less, and even more preferably 15% by mass or less.

[0070] When the content of the third monomer is 1% by mass or more, the effect of adding the trifunctional or higher functional (meth)acrylate monomer can be more effectively exhibited. When the content of the third monomer is less than 20% by mass, the tensile strength and tensile elongation at break of the molded article obtained by curing the photocurable composition can be well balanced.

[0071] It is preferable that the content of the urethane (meth)acrylate oligomer, the content of the first monomer, the content of the second monomer, and the content of the third monomer are each appropriately selected from the above ranges so that the total content of the urethane (meth)acrylate oligomer and the vinyl monomer is 100 mass%.

[0072] 3. Other ingredients The photocurable composition of the present invention preferably contains a photopolymerization initiator. By containing the photopolymerization initiator, the curing of the photocurable composition can be promoted. The photopolymerization initiator is not particularly limited, and any known photopolymerization initiator that generates radicals upon irradiation with light can be used.

[0073] Examples of the photopolymerization initiator include alkylphenones such as 2-hydroxy-2-methylpropiophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, 2-(4-(methylthio)benzoyl)-2-(4-morpholinyl)propane, 2-(dimethylamino)-1-(4-morpholinophenyl)-2-benzyl-1-butanone, and 2-(dimethylamino)-2-(4-methylbenzyl)-1-(4-morpholinophenyl)butan-1-one; Acylphosphine oxides such as phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide and 2,4,6-trimethylbenzoyldiphenylphosphine oxide; Examples include oxime esters such as 1,2-octanedione, 1-(4-(phenylthio)-, 2-(O-benzoyloxime)), ethanone, 1-(9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl)-, 1-(O-acetyloxime).

[0074] In the stereolithography method, a light source having a peak light intensity wavelength in the wavelength range of 390 nm to 410 nm, particularly a light source having a peak light intensity wavelength of 405 nm, is mainly used. It is preferable to initiate radical polymerization of the photocurable composition by irradiating it with light from such a light source. The photopolymerization initiator may be used alone or in combination of two or more.

[0075] In stereolithography using the above-described light source, from the viewpoint of favorably curing the photocurable composition, the photocurable composition of the present invention preferably contains at least two or more photopolymerization initiators with different absorption bands. For example, it is preferable to use a photopolymerization initiator having an absorption band in the 405 nm wavelength region and a photopolymerization initiator having an absorption band in the 300 to 380 nm wavelength region in combination. In the present invention, it is preferable to use an alkylphenone-based photopolymerization initiator and an acylphosphine oxide-based photopolymerization initiator in combination as the photopolymerization initiator.

[0076] The content of the photopolymerization initiator is preferably 1 part by mass or more, more preferably 1.5 parts by mass or more, and even more preferably 2 parts by mass or more, relative to 100 parts by mass of the total content of the urethane (meth)acrylate oligomer and the vinyl monomer; and is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, even more preferably 10 parts by mass or less, and particularly preferably 5 parts by mass or less.

[0077] When an alkylphenone-based photopolymerization initiator and an acylphosphine oxide-based photopolymerization initiator are used in combination, the mass ratio thereof (alkylphenone-based / acylphosphine oxide-based) is preferably 0.2 or more, more preferably 0.5 or more, and even more preferably 0.8 or more, and is preferably 5 or less, more preferably 3 or less, and even more preferably 2 or less.

[0078] The photocurable composition of the present invention may further contain various additives as long as the effects of the present invention are not impaired. Examples of additives include silane coupling agents, diluent polymers, photosensitizers, fillers, UV blocking agents, dyes, pigments, leveling agents, flowability modifiers, antifoaming agents, plasticizers, polymerization inhibitors, flame retardants, dispersion stabilizers, storage stabilizers, antioxidants, metals, metal oxides, metal salts, and ceramics. The photocurable composition may contain one type of additive or two or more types of additives.

[0079] The photocurable composition of the present invention can be easily produced by mixing a urethane (meth)acrylate oligomer, a vinyl monomer, and, if necessary, a photopolymerization initiator and various additives.

[0080] The photocurable composition of the present invention can be suitably used for stereolithography.

[0081] <Method for manufacturing 3D objects using stereolithography> The present invention includes a method for producing a three-dimensional object by stereolithography using the photocurable composition of the present invention. The method for producing a three-dimensional object by stereolithography of the present invention preferably includes a step of curing the photocurable composition of the present invention by irradiating it with light, and a step of forming the cured photocurable composition into a three-dimensional shape. In the present invention, a three-dimensional object produced by stereolithography may be simply referred to as a "molded product."

[0082] As a method for manufacturing the molded body of the present invention, various types of stereolithography methods can be used, such as the SLA method (stereolithography laser method: stereolithography apparatus), the DLP method (digital light processing method: stereolithography projector (surface exposure) method), and the LCD method (liquid crystal display method: stereolithography liquid display).

[0083] The method of manufacturing a three-dimensional object by the stereolithography of the present invention preferably includes, for example, the following first to Nth steps.

[0084] In the first step, the photocurable composition of the present invention is supplied onto a modeling table, and the photocurable composition is irradiated with light to cure the photocurable composition, thereby forming a first layer of a cured product. The photocurable composition is preferably supplied in the form of a layer onto the modeling table. The photocurable composition only needs to be applied to a position on the modeling table that corresponds to the final three-dimensional shape, and is not necessarily applied to the entire surface of the modeling table.

[0085] In the second step, a photocurable composition is applied onto the cured product of the first layer, and the photocurable composition is irradiated with light to cure the photocurable composition, thereby forming a second layer made of the cured product. The photocurable composition is preferably applied in a layer form onto the first layer. The photocurable composition only needs to be applied to a position on the first layer that corresponds to the final three-dimensional shape, and is not necessarily applied to the entire surface of the first layer.

[0086] It is preferable to repeat the second step up to an Nth step (N is a natural number of 3 or more). In the Nth step, a photocurable composition is supplied onto the cured product of the (N-1)th layer, and the photocurable composition is irradiated with light to cure the photocurable composition, thereby forming an Nth layer made of a cured product. It is preferable that the photocurable composition is supplied in the form of a layer on the (N-1)th layer. The photocurable composition only needs to be applied to a position on the (N-1)th layer that corresponds to the final three-dimensional shape, and is not necessarily applied to the entire surface of the (N-1)th layer.

[0087] By carrying out the first step to the Nth step, the photocurable composition is molded into a three-dimensional object in which the cured product is layered.

[0088] In the method for manufacturing a three-dimensional object by the stereolithography of the present invention, it is preferable to use a known 3D printer. As the 3D printer, a commercially available product can be used.

[0089] In the stereolithography method, the thickness of one layer when the photocurable composition is cured is preferably, for example, about 0.01 mm to 0.5 mm. The light to be irradiated is generally ultraviolet light, and preferably contains light with a wavelength of 405 nm. The illuminance of the irradiated light is 0.1 mW / cm in the measurement wavelength range of 405 nm. 2 ~100mW / cm 2 The light irradiation time when curing one layer of the photocurable composition varies depending on the type of stereolithography method used and is adjusted appropriately. For example, in the case of the DLP method, it is about 1 to 60 seconds. The molded article of the present invention is preferably produced in an environment at about room temperature (for example, 20°C to 30°C).

[0090] Furthermore, after the above-mentioned stereolithography, general secondary treatments such as high-pressure mercury lamp irradiation, metal halide lamp irradiation, UV-LED irradiation, and heating can be performed as needed. These secondary treatments can modify the surface after modeling, improve strength, and accelerate hardening. Although it is not always necessary as it may not be necessary depending on the stereolithography conditions, secondary treatments can be performed in conjunction with stereolithography.

[0091] <Molded body and cured product> The present invention includes a cured product and a molded article obtained by curing the photocurable composition of the present invention.

[0092] The cured product and molded article of the present invention preferably have rubber elasticity as a mechanical property. For example, the cured product and molded article of the present invention preferably have the following mechanical properties.

[0093] The hardness of the cured product and molded article of the present invention is preferably 20 or more, more preferably 25 or more, and even more preferably 30 or more, in Shore A hardness, and is preferably 100 or less, more preferably 90 or less, and even more preferably 80 or less. This is because, when the hardness of the cured product and molded article of the present invention is within the above range, they serve as a substitute for the required rubber elasticity.

[0094] The tensile strength at break of the cured product and molded article of the present invention is preferably 1.5 MPa or more, more preferably 2.0 MPa or more, and even more preferably 3.0 MPa or more. This is because, as long as the tensile strength at break of the cured product and molded article of the present invention is within the above range, they can serve as a substitute for the required rubber elasticity. The upper limit of the tensile strength at break is not particularly limited, but is usually 50.0 MPa.

[0095] The tensile elongation at break of the cured product and molded article of the present invention is preferably 50% or more, more preferably 80% or more, and even more preferably 100% or more. This is because, if the tensile elongation at break of the cured product and molded article of the present invention is within the above range, it will serve as a substitute for the required rubber elasticity. The upper limit of the tensile elongation at break is not particularly limited, but is usually 500%.

[0096] The physical properties are values ​​measured by the methods described below. [Example]

[0097] The present invention will be described in detail below with reference to examples. However, the present invention is not limited to the following examples, and all modifications and embodiments that do not deviate from the spirit of the present invention are included within the scope of the present invention.

[0098] 1. Evaluation Method (Hardness of cured product (molded product)) The Shore A hardness of the cured product (molded product) obtained by curing the photocurable composition (in the shape of a compressed ball of φ29 × 12.5 mm according to JIS K6262:2013) was measured in accordance with the method specified in JIS K6253-3:2012.

[0099] (Tensile test of cured product (molded product)) The cured product (molded product) obtained by curing the photocurable composition (shape of a dumbbell-shaped No. 3 test piece according to JIS K6251:2017) was measured for tensile strength and elongation at break according to the specifications of JIS K6251:2017. The higher the tensile strength at break, the stronger the cured product (molded product), and the higher the tensile elongation at break, the easier it is to elongate, which indicates that the cured product (molded product) has good mechanical properties.

[0100] 2. Preparation of photocurable composition The following materials were mixed and degassed using a rotating / revolving mixer in the blending ratios (parts by mass) shown in Table 1 to prepare photocurable compositions. Each component was mixed so that it was homogeneous. In Table 1, "-" indicates that the component was not blended.

[0101] The materials used in Table 1 were as follows: Urethane (meth)acrylate oligomer: Arkema CN8899NS (aliphatic urethane acrylate oligomer, viscosity at 60°C: 25,000 mPa·s-35,000 mPa·s, glass transition temperature: -80°C) First vinyl monomer: MEDOL-10 (2-methyl-2-ethyl-1,3-dioxolan-4-yl) methyl acrylate manufactured by Osaka Organic Chemical Industry Co., Ltd., molecular weight: 200.2, viscosity at 25°C: 5.1 mPa·s, glass transition temperature: -7°C) Secondary vinyl monomer: IBXA (isobornyl acrylate, molecular weight: 208.3, viscosity at 25°C: 7.7 mPa·s, glass transition temperature: 97°C) manufactured by Osaka Organic Chemical Industry Co., Ltd. Trifunctional (meth)acrylate monomer: SR9020NS (propoxylated (3) glyceryl triacrylate manufactured by Arkema (a compound represented by formula (2) in which X = Y = Z = 1, R 1 ~R 3 = propylene group, R 4 = acryloyl group), molecular weight: 428.5, viscosity at 25°C: 95 mPa s, glass transition temperature: 18°C Photopolymerization initiator 1: Omnirad 819 manufactured by IGM Resins BV (acylphosphine oxide photopolymerization initiator, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, molecular weight: 418.5) Photopolymerization initiator 2: Omnirad 1173 manufactured by IGM Resins BV (alkylphenone photopolymerization initiator, 2-hydroxy-2-methylpropiophenone, molecular weight: 164.2, viscosity at 25°C: 25 mPa·s)

[0102] [Table 1]

[0103] 3. Manufacturing of molded bodies (three-dimensional objects) The photocurable composition was used to form a molded article by DLP stereolithography. Specifically, a 3D printer equipped with a light source (UV-LED) with a peak wavelength of 405 nm was used, and the temperature was 23°C, the layer pitch was 0.1 mm, the irradiation time was 20 seconds per layer, and the illuminance at the wavelength of 405 nm was 5.0 mW / cm. 2 The samples were molded into compacts under the conditions shown above. Two different shapes were fabricated for each compact. The first was the shape of the φ29 x 12.5 mm test piece specified in JIS K6262:2013 used in the hardness measurement described above, and the second was the shape of the dumbbell-shaped No. 3 test piece specified in JIS K6251:2017 used in the tensile test described above.

[0104] The hardness, tensile strength at break, and tensile elongation at break of the obtained molded body were measured. The results are shown in Table 1.

[0105] The results in Table 1 show that photocurable compositions of the present invention, which contain a urethane (meth)acrylate oligomer and vinyl monomers including a monofunctional first monomer with a glass transition temperature (Tg1) of -100°C or higher and 10°C or lower, a monofunctional second monomer with a glass transition temperature (Tg2) of 70°C or higher and 150°C or lower, and a third monomer containing a trifunctional or higher (meth)acrylate monomer, produce molded articles with excellent mechanical properties and are suitable for use in stereolithography. In particular, molded articles obtained by curing photocurable compositions Nos. 3 to 6 have a rubber-like tensile break elongation of 50% or higher, yet a tensile break strength of 1.5 MPa or higher, demonstrating a good balance between tensile break elongation and tensile break strength. [Industrial Applicability]

[0106] The photocurable composition of the present invention is suitable for use in stereolithography.

[0107] A preferred embodiment (1) of the present invention is a photocurable composition comprising a urethane (meth)acrylate oligomer and, as vinyl monomers, a monofunctional first monomer having a glass transition temperature (Tg1) of -100°C or higher and 10°C or lower, a monofunctional second monomer having a glass transition temperature (Tg2) of 70°C or higher and 150°C or lower, and a third monomer containing a trifunctional or higher (meth)acrylate monomer.

[0108] A preferred embodiment (2) of the present invention is the photocurable composition according to embodiment (1), in which the content of the urethane (meth)acrylate oligomer is 30% by mass or more, when the total content of the urethane (meth)acrylate oligomer and the vinyl monomer is 100% by mass.

[0109] A preferred embodiment (3) of the present invention is the photocurable composition according to embodiment (1) or (2), in which the content of the third monomer is less than 20% by mass when the total content of the urethane (meth)acrylate oligomer and the vinyl monomer is taken as 100% by mass.

[0110] A preferred embodiment (4) of the present invention is the photocurable composition according to any one of embodiments (1) to (3), in which the urethane (meth)acrylate oligomer includes an aliphatic urethane (meth)acrylate oligomer.

[0111] A preferred aspect (5) of the present invention is the photocurable composition according to any one of aspects (1) to (4), wherein the third monomer contains a compound represented by formula (1) or formula (2) as a trifunctional (meth)acrylate. [ka] [In formula (1), R 1 ~R 3 are the same or different and each is an alkylene group having 2 to 6 carbon atoms. 4 is a methacryloyl group or an acryloyl group. X, Y, and Z each represent an integer of 0 to 10, and the sum of X, Y, and Z is 0 to 20.] [ka] [In formula (2), R 1 ~R 3 are the same or different and each is an alkylene group having 2 to 6 carbon atoms. 4 is a methacryloyl group or an acryloyl group. X, Y, and Z each represent an integer of 0 to 10, and the sum of X, Y, and Z is 0 to 20.]

[0112] A preferred embodiment (6) of the present invention is the photocurable composition according to any one of embodiments (1) to (5), which is for use in stereolithography.

[0113] A preferred embodiment (7) of the present invention is a cured product obtained by curing the photocurable composition according to any one of embodiments (1) to (5).

[0114] A preferred embodiment (8) of the present invention is a molded article obtained by producing the photocurable composition according to any one of embodiments (1) to (5) by a stereolithography method.

[0115] A preferred embodiment (9) of the present invention is a method for producing a three-dimensional object by stereolithography using the photocurable composition according to any one of embodiments (1) to (5).

Claims

1. a urethane (meth)acrylate oligomer; As a vinyl monomer, a monofunctional first monomer having a glass transition temperature (Tg1) of −100° C. or higher and 10° C. or lower; a monofunctional second monomer having a glass transition temperature (Tg2) of 70°C or higher and 150°C or lower; and a third monomer containing a tri- or higher functional (meth)acrylate monomer, a mass ratio of the first monomer to the second monomer (first monomer / second monomer) is 1.6 or more and 15 or less; When the total content of the urethane (meth)acrylate oligomer and the vinyl monomer is taken as 100% by mass, the content of the urethane (meth)acrylate oligomer is 30% by mass or more and 75% by mass or less, the content of the first monomer is 15% by mass or more and 60% by mass or less, the content of the second monomer is 5% by mass or more and 50% by mass or less, the content of the third monomer is 1% by mass or more and less than 20% by mass, the first monomer comprises a (meth)acrylate containing a heterocycle, the second monomer comprises a (meth)acrylate; The photocurable composition for stereolithography, wherein the third monomer contains a compound represented by formula (1) or (2) as a trifunctional (meth)acrylate. 【Chemistry 1】 [In formula (1), R 1 to R 3 are the same or different and each represent an alkylene group having 2 to 6 carbon atoms. R 4 is a methacryloyl group or an acryloyl group. X, Y, and Z each represent an integer of 0 to 10, and the sum of X, Y, and Z is 0 to 20.] 【Chemistry 2】 [In formula (2), R 1 to R 3 are the same or different and each represent an alkylene group having 2 to 6 carbon atoms. R 4 is a methacryloyl group or an acryloyl group. X, Y, and Z each represent an integer of 0 to 10, and the sum of X, Y, and Z is 0 to 20.]

2. The first monomer contains (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate as a (meth)acrylate containing a heterocycle, the second monomer comprises isobornyl acrylate; The photocurable composition for stereolithography according to claim 1, wherein the third monomer is a trifunctional (meth)acrylate compound represented by formula (1) or (2), in which R 1 to R 3 are ethylene groups or propylene groups, R 4 is a methacryloyl group or acryloyl group, and X = Y = Z = 1.

3. A photocurable composition for photopolymerization as described in claim 1, wherein the mass ratio of the first monomer to the second monomer (first monomer / second monomer) is 1.6 or more and 5 or less.

4. The photocurable composition for stereolithography described in claim 1, wherein the third monomer is a compound represented by formula (2), R 1 to R 3 are propylene groups, and R 4 is a methacryloyl group or an acryloyl group.

5. The photocurable composition for stereolithography according to claim 1 , wherein the urethane (meth)acrylate oligomer includes an aliphatic urethane (meth)acrylate oligomer.

6. The first monomer comprises (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate; The photocurable composition for stereolithography according to claim 4 , wherein the second monomer is isobornyl acrylate.

7. When the total content of the urethane (meth)acrylate oligomer and the vinyl monomer is taken as 100% by mass, the content of the first monomer is 25% by mass or more and 50% by mass or less, the content of the second monomer is 10% by mass or more and 20% by mass or less, The photocurable composition for stereolithography according to claim 1 , wherein the content of the third monomer is 3% by mass or more and 15% by mass or less.

8. The photocurable composition for stereolithography according to claim 1, further comprising, as photopolymerization initiators, an alkylphenone-based photopolymerization initiator and an acylphosphine oxide-based photopolymerization initiator in a mass ratio (alkylphenone-based photopolymerization initiator / acylphosphine oxide-based photopolymerization initiator) of 0.2 or more and 5 or less.

9. A photocurable composition for photopolymerization according to any one of claims 1 to 8, wherein the hardness of the cured product is 20 or more and 100 or less in Shore A hardness, the tensile breaking strength of the cured product is 1.5 MPa or more and 50.0 MPa or less, and the tensile breaking elongation of the cured product is 50% or more and 500% or less.

10. A cured product obtained by curing the photocurable composition for stereolithography according to any one of claims 1 to 8.

11. A method for producing a three-dimensional object by a stereolithography method, using the photocurable composition for stereolithography according to any one of claims 1 to 8.

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