Photocurable composition

Abstract

To provide a photocurable composition that yields a molded body having excellent mechanical characteristics.SOLUTION: The photocurable composition of the present invention comprises a urethane (meth)acrylate oligomer and, as vinyl monomers, a first monomer having a glass transition temperature (Tg1) of -100°C or more and 10°C or less and a second monomer having a glass transition temperature (Tg2) of 70°C or more and 150°C or less, and contains 15 pts.mass or more to 65 pts.mass or less of inorganic particles having organic groups on the surface thereof with respect to a total of 100 pts.mass of the urethane (meth)acrylate oligomer and the vinyl monomers.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.

[0005] Patent Document 3 discloses a photocurable composition containing a urethane (meth)acrylate oligomer and, as vinyl monomers, a first monomer having a glass transition temperature (Tg) of -100°C or higher and 20°C or lower and a second monomer having a glass transition temperature (Tg) of more than 20°C and 150°C or lower, wherein the content of the urethane (meth)acrylate oligomer is in the range of 20% to 80% by mass, the content of the first monomer is in the range of 15% to 75% by mass, the content of the second monomer is in the range of 5% to 65% by mass, and the total content of the urethane (meth)acrylate oligomer and the vinyl monomer is 100% by mass. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2017 / 154335 [Patent Document 2] Patent Publication No. 2021-75044 [Patent Document 3] Japanese Patent Application Publication No. 2023-46297 Summary of the Invention [Problem to be solved by the invention]

[0007] 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 molded products with excellent mechanical properties. Another object of the present invention is to provide a photocurable composition that maintains a viscosity that allows stereolithography and provides molded products with excellent tear strength. [Means for solving the problem]

[0008] The photocurable composition of the present invention comprises a urethane (meth)acrylate oligomer and The composition is characterized in that it contains, as vinyl monomers, a first monomer having a glass transition temperature (Tg1) of -100°C or higher and 10°C or lower, and a second monomer having a glass transition temperature (Tg2) of 70°C or higher and 150°C or lower, and contains 15 parts by mass or higher and 65 parts by mass or lower of inorganic particles having organic groups on their surfaces per 100 parts by mass of the total of the urethane (meth)acrylate oligomer and the vinyl monomer.

[0009] The present invention uses inorganic particles having organic groups on their surfaces, which allows the amount of inorganic particles to be increased while suppressing an increase in the viscosity of the photocurable composition, thereby providing a photocurable composition that maintains a viscosity suitable for photolithography and exhibits excellent tear strength for molded articles. [Effects of the Invention]

[0010] The photocurable composition of the present invention can be suitably used for stereolithography. The photocurable composition of the present invention maintains a viscosity that allows for stereolithography and provides molded articles with excellent mechanical properties. DETAILED DESCRIPTION OF THE INVENTION

[0011] <Photocurable composition> The photocurable composition of the present invention comprises a urethane (meth)acrylate oligomer and The vinyl monomers include a first monomer having a glass transition temperature (Tg1) of -100°C or higher and 10°C or lower, and a second monomer having a glass transition temperature (Tg2) of 70°C or higher and 150°C or lower, and the composition contains 15 parts by mass or higher and 65 parts by mass or lower of inorganic particles having organic groups on their surfaces per 100 parts by mass of the total of the urethane (meth)acrylate oligomer and the vinyl monomer.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.).

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 2. Vinyl Monomers The photocurable composition of the present invention contains, as vinyl monomers, a first monomer having a glass transition temperature (Tg1) of -100°C or higher and 10°C or lower, and a second monomer having a glass transition temperature (Tg2) of 70°C or higher and 150°C or lower.

[0036] The photocurable composition contains, as the vinyl monomer, a first monomer having a glass transition temperature (Tg1) of -100°C or more and 10°C or less, and a second monomer having a glass transition temperature (Tg2) of 70°C or more and 150°C or less, so that the molded article obtained by curing the composition has excellent mechanical properties.

[0037] In the present invention, the term "vinyl monomer" refers to a monomer having a 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] Examples of the vinyl monomer include monofunctional (monofunctional) monomers and polyfunctional monomers (e.g., bifunctional monomers, trifunctional monomers, tetrafunctional monomers, etc.). From the viewpoint of achieving a viscosity suitable for stereolithography and exhibiting excellent properties in the elastic molded article obtained by curing, preferred are monofunctional to tetrafunctional monomers. The use of monofunctional monomers is preferred from the viewpoint of reducing the viscosity of the photocurable composition in a room temperature environment. The use of polyfunctional monomers is also preferred from the viewpoint of exhibiting excellent properties in the molded article.

[0040] The vinyl monomer preferably contains (meth)acrylate, since this provides a viscosity suitable for stereolithography and excellent photocuring reactivity.

[0041] Preferred monofunctional monomers include monofunctional (meth)acrylates. Specific examples of the monofunctional (meth)acrylates include ethoxylated nonylphenol acrylate, methyl-2-allyloxymethyl 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, (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, tricyclodecanyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, cyclohexyl (meth)acrylate, 4-butylcyclohexyl (meth)acrylate, acryloylmorpholine, 2-hydroxyethyl (meth)acrylate, 2-hydroxy Propyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)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 ) acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)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,Examples of the vinyl monomers include N-diethyl(meth)acrylamide, N,N-dimethylaminopropyl(meth)acrylamide, hydroxybutyl vinyl ether, lauryl vinyl ether, cetyl vinyl ether, 2-ethylhexyl vinyl ether, polyoxyethylene nonylphenyl ether (meth)acrylate, and vinyl monomers (such as N-vinylpyrrolidone, N-vinylcaprolactam, vinylimidazole, and vinylpyridine).

[0042] Specific examples of polyfunctional (meth)acrylates include polyethylene glycol di(meth)acrylate, dipropylene glycol diacrylate, propoxylated pentyl glycol diacrylate, propoxylated glyceryl triacrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, and trimethylol Examples of such an acrylate include propane trioxyethyl (meth)acrylate, tris(2-hydroxyethyl) isocyanurate tri(meth)acrylate, tris(acryloyloxy) isocyanurate, bis(hydroxymethyl)tricyclodecane di(meth)acrylate, dipentaerythritol hexa(meth)acrylate, diol di(meth)acrylate which is an adduct of bisphenol A with polyethylene oxide or propylene oxide, diol di(meth)acrylate which is an adduct of hydrogenated bisphenol A with ethylene oxide or propylene oxide, epoxy (meth)acrylate in which a (meth)acrylate is added to a diglycidyl ether of bisphenol A, and triethylene glycol divinyl ether.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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).

[0048] 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 /

[0049] 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 20% by mass or more, more preferably 30% by mass or more, and even more preferably 35% by mass or more, and is preferably 80% by mass or less, more preferably 60% by mass or less, and even more preferably 45% by mass or less.

[0050] When the content of the urethane (meth)acrylate oligomer is 80% 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 20% by mass or more, the mechanical strength of the molded article obtained by curing the photocurable composition is not reduced.

[0051] 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 20% by mass or more, more preferably 40% by mass or more, even more preferably 55% by mass or more, and is preferably 80% by mass or less, more preferably 70% 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.

[0052] When the total content of the urethane (meth)acrylate oligomer and the vinyl monomer is 100% by mass, the content of the first monomer is preferably 15% by mass or more, more preferably 30% by mass or more, even more preferably 40% by mass or more, and preferably 75% by mass or less, more preferably 60% 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.

[0053] 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 10% by mass or more, even more preferably 15% by mass or more, and preferably 65% ​​by mass or less, more preferably 50% by mass or less, and even more preferably 30% by mass or less. When 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).

[0054] It is preferable that the content of the first monomer and the content of the second 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% by mass.

[0055] 3. Inorganic particles with organic groups on the surface The photocurable composition of the present invention contains inorganic particles having organic groups on their surfaces, such as oxides such as silica, alumina, magnesium oxide, titanium oxide, zinc oxide, and ferrite; calcium carbonate; silicates such as talc, mica, clay, and xonotlite; hydroxides such as aluminum hydroxide and magnesium hydroxide; and metal particles such as aluminum powder and tungsten powder.

[0056] The organic group on the surface of the inorganic particles is preferably a monovalent functional group containing carbon and having a polymerizable carbon-carbon double bond that reacts with a urethane (meth)acrylate oligomer or a vinyl monomer. The organic group having a polymerizable carbon-carbon double bond provides a highly polymerizable functional group. Furthermore, this double bond is highly reactive, enabling the formation of polymers with a variety of functions.

[0057] The organic group may be any group as long as it partially contains a polymerizable carbon-carbon double bond, and examples thereof include an alkenyl group, an alkanoyl group, or an organic group in which some of the hydrogen atoms have been substituted. The number of carbon atoms in the organic group is preferably 2 or more and 18 or less, more preferably 10 or less, and even more preferably 5 or less.

[0058] The inorganic particles used in the present invention preferably have an organic group having a polymerizable carbon-carbon double bond and 2 to 18 carbon atoms, more preferably a vinyl group, an isopropenyl group, a 1-propenyl group, a 2-propenyl group, or a (meth)acryloyl group. The (meth)acryloyl group means a methacryloyl group and / or an acryloyl group.

[0059] The organic group can be introduced to the surface of inorganic particles by reacting the hydroxyl group present on the surface of inorganic particles with a silane coupling agent having an organic group. Examples of inorganic particles having a hydroxyl group on the surface include oxides such as silica, alumina, magnesium oxide, zinc oxide, and ferrite; glass beads; silicates such as talc, mica, clay, and xonotlite; and hydroxides such as aluminum hydroxide and magnesium hydroxide.

[0060] The organic groups on the surfaces of the inorganic particles are preferably those introduced onto the silica surface by reacting silanol groups present on the silica surface with a silane coupling agent having an organic group, and more preferably those introduced onto the silica surface by reacting silanol groups present on the silica surface with (meth)acryloxysilane or vinylsilane.

[0061] The silane coupling agent is not particularly limited, but examples thereof include alkylalkoxysilanes such as methyltrimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, and triethoxy-n-octylsilane; vinylsilanes such as vinyltrimethoxysilane and vinyltriethoxysilane; aminosilanes such as γ-aminopropyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, and N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane; and γ-glycidoxypropyltrimethoxysilane. Examples of suitable silanes include epoxy silanes such as 3-methacryloxypropylmethyldimethoxysilane, β-glycidoxypropylmethyldimethoxysilane, methacryloxysilanes such as 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, and 3-methacryloxypropyltriethoxysilane, acryloxysilanes such as 3-acryloxypropyltrimethoxysilane, and mercaptosilanes such as γ-mercaptopropyltrimethoxysilane (3-mercaptopropyltrimethoxysilane).

[0062] The photocurable composition of the present invention preferably contains, as inorganic particles having an organic group, first inorganic particles having a median diameter (50% diameter in cumulative volume distribution) of 0.2 μm or more and 5.0 μm or less.

[0063] The median diameter (50% diameter in cumulative volume distribution) of the first inorganic particles is preferably 0.2 μm or more, more preferably 0.5 μm or more, even more preferably 1.0 μm or more, and is preferably 5.0 μm or less, more preferably 3.0 μm or less, and even more preferably 2.0 μm or less. When the median diameter of the first inorganic particles is within the above range, an increase in viscosity of the photocurable composition can be suppressed, and the mechanical strength of the molded product can be increased.

[0064] The photocurable composition of the present invention preferably contains, in addition to the first inorganic particles, second inorganic particles having a median diameter (50% diameter in cumulative volume distribution) of 0.005 μm to 0.15 μm as inorganic particles having organic groups on their surfaces. By using inorganic particles with different particle diameters, it is possible to increase the content of inorganic particles while suppressing an increase in the viscosity of the photocurable composition. As a result, it is possible to increase the filling rate of inorganic particles in the molded product, and to improve the mechanical strength of the molded product.

[0065] The median diameter (50% diameter in the cumulative volume distribution) of the second inorganic particles is preferably 0.005 μm or more, more preferably 0.01 μm or more, even more preferably 0.02 μm or more, and preferably 0.15 μm or less, more preferably 0.1 μm or less, and even more preferably 0.08 μm or less. When the median diameter of the second inorganic particles is within the above range, the content of the inorganic particles can be increased while suppressing an increase in the viscosity of the photocurable composition. As a result, the filling rate of the inorganic particles in the molded body can be increased, and the mechanical strength of the molded body can be improved.

[0066] The ratio (MD2 / MD1) of the median diameter (MD2) of the second inorganic particles to the median diameter (MD1) of the first inorganic particles is preferably 1 / 50 or more, more preferably 1 / 30 or more, even more preferably 1 / 15 or more, and preferably 1 / 5 or less, more preferably 1 / 6 or less, and even more preferably 1 / 7 or less. When the ratio (MD2 / MD1) of the median diameter (MD2) of the second inorganic particles to the median diameter (MD1) of the first inorganic particles is within the above range, the content of the inorganic particles can be increased while suppressing an increase in the viscosity of the photocurable composition. As a result, the filling rate of the inorganic particles in the molded body can be increased, and the mechanical strength of the molded body can be improved.

[0067] The median diameter is measured by dynamic light scattering (DLS). When inorganic particles aggregate, the median diameter is measured in the state of primary particles in which the aggregated particles are dispersed.

[0068] The BET specific surface area of ​​the first inorganic particles is 1 m 2 / g or more is preferable, and 2m 2 / g or more is more preferable, and 3m 2 / g or more is more preferable, and 20m 2 / g or less is preferable, and 15m 2 / g or less is more preferable, and 10m 2 / g or less is more preferable.

[0069] The BET specific surface area of ​​the second inorganic particles is 25 m 2 / g or more is preferable, and 30m 2 / g or more is more preferable, and 50m 2 / g or more is more preferable, and 300m 2 / g or less is preferable, and 200m 2 / g or less is more preferable, and 100m 2 / g or less is more preferable.

[0070] The mass ratio of the second inorganic particles to the first inorganic particles (second inorganic particles / first inorganic particles) is preferably 1 / 200 or more, more preferably 1 / 150 or more, even more preferably 1 / 120 or more, and preferably 1 / 8 or less, more preferably 1 / 15 or less, and even more preferably 1 / 50 or less. When the mass ratio of the second inorganic particles to the first inorganic particles (second inorganic particles / first inorganic particles) is within the above range, the content of the inorganic particles can be increased while suppressing an increase in the viscosity of the photocurable composition. As a result, the filling rate of the inorganic particles in the molded body can be increased, and the mechanical strength of the molded body can be improved.

[0071] The photocurable composition of the present invention preferably contains 15 parts by mass or more, more preferably 20 parts by mass or more, and even more preferably 25 parts by mass or more, and preferably 65 parts by mass or less, more preferably 60 parts by mass or less, and even more preferably 55 parts by mass or less, of inorganic particles having organic groups on their surfaces, relative to 100 parts by mass of the total of the urethane (meth)acrylate oligomer and vinyl monomer. This is because, when the content of the inorganic particles having organic groups on their surfaces in the photocurable composition is within the above range, the mechanical strength of the molded product is improved.

[0072] 4. 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 is subjected to a shear rate of 100 s using an E-type viscometer at a temperature of 25°C and a relative humidity of 50%. -1 The viscosity measured under these conditions is preferably 0.1 Pa·s or more, more preferably 0.5 Pa·s or more, and even more preferably 1 Pa·s or more, and is preferably 6.0 Pa·s or less, more preferably 3.0 Pa·s or less, and even more preferably 1.5 Pa·s or less. When the viscosity of the photocurable composition is within this range, it is possible to provide a viscosity suitable for stereolithography in a room temperature environment, while imparting elasticity to the molded article obtained by curing. Furthermore, when the viscosity of the photocurable composition is within this range, workability is good.

[0080] 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.

[0081] The photocurable composition of the present invention can be suitably used for stereolithography.

[0082] <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."

[0083] 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).

[0084] 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 based on design data of the three-dimensional shape.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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).

[0091] 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.

[0092] <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.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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%.

[0097] The tear strength (kN / m) of the cured product and molded article of the present invention is preferably 5 or more, more preferably 10 or more, even more preferably 15 or more, and is preferably 40 or less, more preferably 35 or less, and even more preferably 30 or less. This is because, if the tear strength of the cured product and molded article of the present invention is within the above range, a good balance with other mechanical strengths is achieved.

[0098] The physical properties are values ​​measured by the methods described below. [Example]

[0099] 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.

[0100] 1. Evaluation Method

[0101] (Measurement of Viscosity of Photocurable Composition) The viscosity of the photocurable composition before curing was measured using an Anton Paar E-type viscometer at a temperature of 25°C and a relative humidity of 50%, with a cone plate of φ25 mm and a shear rate of 100 s -1 The measurement was carried out under the following conditions.

[0102] (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.

[0103] (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.

[0104] (Tear strength test of cured product (molded product)) The tear strength (kN / m) of the cured product (molded product) obtained by curing the photocurable composition (uncut angle shape according to JIS K6251:2015) was measured in accordance with the provisions of JIS K6251:2015. The higher the tear strength value, the stronger the cured product (molded product) is, and the better the mechanical properties of the cured product (molded product) are judged to be.

[0105] (3D printer modeling capabilities) If the molded body was completely formed using the 3D printer, it was rated as "OK", but if there was a partial defect or the body could not be formed, it was rated as "NO".

[0106] 2. Preparation of photocurable composition The following materials were mixed and degassed using a rotating / revolving mixer to obtain the blending ratios (parts by mass) shown in Tables 1 to 4, to prepare photocurable compositions. Each component was mixed uniformly. In Tables 1 to 4, "-" indicates that the component was not blended.

[0107] The materials used in Tables 1 to 4 are 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. Silica 1: Admatec SC2500-SMJ (silica with methacryloyl groups, median diameter (primary particle diameter) 500 nm, BET specific surface area 5.2 m 2 / g) Silica 2: Admatec SC5500-SMJ (silica with methacryloyl groups, median diameter (primary particle diameter) 1500 nm, BET specific surface area 3.4 m 2 / g) Silica 3: Nipsil KQ (amorphous silicon dioxide, primary particle size 13.9 nm, BET specific surface area 207 m) manufactured by Tosoh Corporation 2 / g) Silica 4: Nipsil VN3#100 manufactured by Tosoh Corporation (amorphous silicon dioxide, primary particle diameter 17.1 nm, BET specific surface area 192 m) 2 / g) Silica 5: YA050C-SM1 manufactured by Admatec Co., Ltd. (silica with methacryloyl groups, median diameter (primary particle diameter) 50 nm, BET specific surface area 65 m 2 / g) Silane coupling agent: Triethoxy-n-octylsilane (silicon compound alkylsilane, triethoxy-n-octylsilane, molecular weight: 276.5) manufactured by Tokyo Chemical Industry Co., Ltd. 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)

[0108] [Table 1]

[0109] [Table 2]

[0110] [Table 3]

[0111] [Table 4]

[0112] 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 above conditions. Three different shapes were fabricated for each compact. The first was the shape of a φ29 x 12.5 mm test piece according to JIS K6262:2013, which was used in the hardness measurement described above. The second was the shape of a dumbbell-shaped No. 3 test piece according to JIS K6251:2017, which was used in the tensile test described above. The third was the shape of an angled piece without notches according to JIS K6251:2015, which was used in the tear strength test described above.

[0113] The hardness, tensile strength at break, tensile elongation at break, and tear strength of the obtained molded article were measured, and the results are shown in Tables 1 to 4.

[0114] The results in Tables 1 to 3 show that the photocurable composition of the present invention, which contains a urethane (meth)acrylate oligomer and, as vinyl monomers, a first monomer having a glass transition temperature (Tg1) of -100°C or higher and 10°C or lower and a second monomer having a glass transition temperature (Tg2) of 70°C or higher and 150°C or lower, and which contains 15 parts by mass or higher and 65 parts by mass or lower of inorganic particles having organic groups on their surfaces per 100 parts by mass of the total of the urethane (meth)acrylate oligomer and the vinyl monomer, gives molded articles with excellent mechanical properties and has a viscosity range that is suitable for use in stereolithography.

[0115] The results in Table 4 show that photocurable compositions No. 21 to No. 23, which contain first inorganic particles with a median diameter of 0.2 μm to 5.0 μm and second inorganic particles with a median diameter of 0.005 μm to 0.15 μm as inorganic particles having organic groups on their surfaces, can produce molded articles with improved tear strength while suppressing viscosity increase compared to photocurable composition No. 4, which has the same silica content. [Industrial Applicability]

[0116] The photocurable composition of the present invention is suitable for use in stereolithography.

[0117] A preferred embodiment (1) of the present invention is a photocurable composition comprising a urethane (meth)acrylate oligomer and, as vinyl monomers, a first monomer having a glass transition temperature (Tg1) of −100° C. or higher and 10° C. or lower and a second monomer having a glass transition temperature (Tg2) of 70° C. or higher and 150° C. or lower, and comprising 15 parts by mass or more and 65 parts by mass or less of inorganic particles having organic groups on their surfaces per 100 parts by mass of the urethane (meth)acrylate oligomer and the vinyl monomer combined.

[0118] A preferred embodiment (2) of the present invention is the photocurable composition of embodiment (1), wherein the inorganic particles having organic groups on the surface thereof are first inorganic particles having a median diameter of 0.2 μm to 5.0 μm.

[0119] A preferred embodiment (3) of the present invention is the photocurable composition of embodiment (2), wherein the inorganic particles having organic groups on the surface thereof further contain second inorganic particles having a median diameter of 0.005 μm to 0.15 μm.

[0120] A preferred embodiment (4) of the present invention is the photocurable composition of embodiment (3), in which the ratio (MD2 / MD1) of the median diameter (MD2) of the second inorganic particles to the median diameter (MD1) of the first inorganic particles is 1 / 50 or more and 1 / 5 or less.

[0121] A preferred embodiment (5) of the present invention is the photocurable composition of embodiment (3) or (4), in which the mass ratio of the second inorganic particles to the first inorganic particles (second inorganic particles / first inorganic particles) is 1 / 200 or more and 1 / 8 or less.

[0122] A preferred embodiment (6) of the present invention is the photocurable composition according to any one of embodiments (1) to (5), in which the organic group is an organic group having 2 to 18 carbon atoms and containing a polymerizable carbon-carbon double bond.

[0123] A preferred embodiment (7) of the present invention is the photocurable composition according to any one of embodiments (1) to (6), in which the organic group is a vinyl group, an isopropenyl group, a 1-propenyl group, a 2-propenyl group, or a (meth)acryloyl group.

[0124] A preferred embodiment (8) of the present invention is the photocurable composition according to any one of embodiments (1) to (7), in which the inorganic particles are silica.

[0125] In a preferred embodiment (9) of the present invention, the BET specific surface area of ​​the inorganic particles is 10 m 2 The photocurable composition according to any one of aspects (1) to (8), wherein the .lambda. / g or less.

[0126] A preferred aspect (10) of the present invention is the photocurable composition according to any one of aspects (1) to (9), in which the content of the urethane (meth)acrylate oligomer is in the range of 20% by mass to 80% by mass, the content of the first monomer is in the range of 15% by mass to 75% by mass, the content of the second monomer is in the range of 5% by mass to 65% by mass, and the total content of the urethane (meth)acrylate oligomer and vinyl monomer is 100% by mass.

[0127] A preferred embodiment (11) of the present invention is the photocurable composition according to any one of embodiments (1) to (10), wherein the urethane (meth)acrylate oligomer has a (meth)acryloyl group.

[0128] A preferred embodiment (12) of the present invention is the photocurable composition according to any one of embodiments (1) to (11), wherein the urethane (meth)acrylate oligomer has a glass transition temperature (Tg) of -100°C to 50°C.

[0129] A preferred embodiment (13) of the present invention is the photocurable composition according to any one of embodiments (1) to (12), wherein the vinyl monomer is at least one selected from the group consisting of a monofunctional vinyl monomer, a difunctional vinyl monomer, a trifunctional vinyl monomer, and a tetrafunctional vinyl monomer.

[0130] A preferred embodiment (14) of the present invention is the photocurable composition according to any one of embodiments (1) to (13), in which the vinyl monomer comprises a (meth)acrylate.

[0131] A preferred embodiment (15) of the present invention is a method for producing a cellulose acetate copolymer having a viscosity (temperature 25°C, shear rate 100 s -1 ) is 6.0 Pa·s or less.

[0132] A preferred embodiment (16) of the present invention is the photocurable composition according to any one of embodiments (1) to (15), which is for use in stereolithography.

Claims

1. a urethane (meth)acrylate oligomer; As a vinyl monomer, a first monomer having a glass transition temperature (Tg1) of −100° C. or higher and 10° C. or lower; a second monomer having a glass transition temperature (Tg2) of 70°C or higher and 150°C or lower; A photocurable composition comprising 15 parts by mass or more and 65 parts by mass or less of inorganic particles having organic groups on their surfaces, per 100 parts by mass of a total of a urethane (meth)acrylate oligomer and a vinyl monomer.

2. 2. The photocurable composition according to claim 1, wherein the inorganic particles having an organic group on the surface thereof are first inorganic particles having a median diameter of 0.2 μm to 5.0 μm.

3. 3. The photocurable composition according to claim 2, further comprising second inorganic particles having a median diameter of 0.005 μm to 0.15 μm as the inorganic particles having organic groups on the surface thereof.

4. The photocurable composition according to claim 3, wherein the ratio (MD2 / MD1) of the median diameter (MD2) of the second inorganic particles to the median diameter (MD1) of the first inorganic particles is 1 / 50 or more and 1 / 5 or less.

5. The photocurable composition according to claim 3 , wherein the mass ratio of the second inorganic particles to the first inorganic particles (second inorganic particles / first inorganic particles) is 1 / 200 or more and 1 / 8 or less.

6. 4. The photocurable composition according to claim 1, wherein the organic group is an organic group having 2 to 18 carbon atoms and containing a polymerizable carbon-carbon double bond.

7. 4. The photocurable composition according to claim 1, wherein the organic group is a vinyl group, an isopropenyl group, a 1-propenyl group, a 2-propenyl group, or a (meth)acryloyl group.

8. 4. The photocurable composition according to claim 1, wherein the inorganic particles are silica particles.

9. The BET specific surface area of ​​the first inorganic particles is 10 m ２ The photocurable composition according to claim 1, wherein the viscosity is 1 / g or less.

10. The content of the urethane (meth)acrylate oligomer is in the range of 20% by mass to 80% by mass, the content of the first monomer is in the range of 15% by mass to 75% by mass, the content of the second monomer is in the range of 5% by mass to 65% by mass, 4. The photocurable composition according to claim 1, wherein the total content of the urethane (meth)acrylate oligomer and the vinyl monomer is 100% by mass.

11. 4. The photocurable composition according to claim 1, wherein the urethane (meth)acrylate oligomer has a (meth)acryloyl group.

12. 4. The photocurable composition according to claim 1, wherein the urethane (meth)acrylate oligomer has a glass transition temperature (Tg) of -100°C to 50°C.

13. 4. The photocurable composition according to claim 1, wherein the vinyl monomer is at least one selected from the group consisting of a monofunctional vinyl monomer, a difunctional vinyl monomer, a trifunctional vinyl monomer, and a tetrafunctional vinyl monomer.

14. The photocurable composition according to claim 1 or 3, wherein the vinyl monomer comprises a (meth)acrylate.

15. Viscosity (temperature 25°C, shear rate 100 s －１ 4. The photocurable composition according to claim 1, wherein the viscosity is 6.0 Pa·s or less.

16. The photocurable composition according to claim 1 or 3, which is used for photolithography.

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