Photocurable composition and molded article made from the same

Abstract

To provide a photocurable composition, a molded article of which has excellent mechanical characteristics.SOLUTION: Provided is a photocurable composition, comprising: a urethane (meth)acrylate oligomer; and as a vinyl monomer, a first monomer having a glass transition temperature of -100°C to 20°C and a second monomer having a glass transition temperature of more than 20°C and 150°C or less. A content ratio of the urethane (meth)acrylate oligomer is 20 mass% to 80 mass%, a content ratio of the first monomer is 15 mass% to 75 mass%, a content ratio of the second monomer is 5 mass% to 65 mass%, and a total content ratio of the urethane (meth)acrylate oligomer and the vinyl monomer is 100 mass%.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 The vinyl monomers include 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, 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, The total content of the urethane (meth)acrylate oligomer and the vinyl monomer is 100% by mass.

[0008] The cured product (molded article) obtained by curing the photocurable composition of the present invention can have a low glass transition temperature (Tg) and has excellent mechanical properties. [Effects of the Invention]

[0009] 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 strength. DETAILED DESCRIPTION OF THE INVENTION

[0010] 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 (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, 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, The total content of the urethane (meth)acrylate oligomer and the vinyl monomer is 100% by mass.

[0011] 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.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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 500 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 5000 or less, hardness can be imparted to a molded article obtained by curing the photocurable composition.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.).

[0030] 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, it 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, it is one in which an aromatic polyisocyanate is the component.

[0031] 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 −80° C. or higher, and is 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.

[0032] 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.

[0033] 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.

[0034] In the photocurable composition of the present invention, 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.

[0035] If the content of the urethane (meth)acrylate oligomer exceeds 80% by mass, the viscosity of the photocurable composition becomes too high, making stereolithography difficult, while if the content of the urethane (meth)acrylate oligomer is less than 20% by mass, the mechanical strength of the molded article obtained by curing the photocurable composition decreases.

[0036] 2. "Vinyl Monomer" In the present invention, the term "vinyl monomer" refers to a monomer having a radically polymerizable carbon-carbon double bond in the molecule. The vinyl monomer preferably contains a first monomer having a homopolymer glass transition temperature (Tg) of -100°C or higher and 20°C or lower, and a second monomer having a homopolymer glass transition temperature (Tg) of more than 20°C and 150°C or lower. By containing the first monomer having a low glass transition temperature and the second monomer having a high glass transition temperature, the molded article obtained by curing the photocurable composition has excellent mechanical strength.

[0037] The glass transition temperature (Tg) of the first monomer is preferably -100°C or higher, more preferably -70°C or higher, even more preferably -50°C or higher, and is preferably 20°C or lower, more preferably 10°C or lower, even more preferably 0°C or lower, and particularly preferably -20°C or lower.

[0038] The glass transition temperature (Tg) of the second monomer is preferably above 20°C, more preferably 70°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, and even more preferably 110°C or lower.

[0039] 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.

[0040] 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).

[0041] 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.

[0042] 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 base, vinyl monomers containing a heterocycle, vinylamide, vinyl monomers containing an epoxy group, vinyl carboxylate, α-olefin, dienes, and (meth)acrylic monomers.

[0043] 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.

[0044] The vinyl monomer preferably contains (meth)acrylate, since this provides a viscosity suitable for stereolithography and excellent photocuring reactivity.

[0045] 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 monomer include N-diethyl(meth)acrylamide, N,N-dimethylaminopropyl(meth)acrylamide, hydroxybutyl 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).

[0046] 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.

[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] Examples of the first monomer having a glass transition temperature (Tg) of -100°C or higher and 20°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.

[0049] Examples of the second monomer having a glass transition temperature (Tg) of more than 20°C and not more than 150°C include isobornyl acrylate (97°C), t-butyl methacrylate (107°C), methyl methacrylate (105°C), acrylamide (165°C), styrene (100°C), acrylic acid (106°C), and acrylonitrile (97°C).

[0050] 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.

[0051] 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 bis(2,4,6-trimethylbenzoyl)phenylphosphine 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).

[0052] In the stereolithography method, a light source having a peak light intensity wavelength 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 that the radical polymerization of the photocurable composition is initiated by irradiation with light from such a light source. The photopolymerization initiator may be used alone or in combination of two or more.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] The photocurable composition of the present invention may contain a silane coupling agent. When the photocurable composition of the present invention contains a filler, the interfacial strength between the filler and the polymer component is increased. As a result, the effect of the filler in improving physical properties is enhanced.

[0057] 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; epoxysilanes such as γ-glycidoxypropyltrimethoxysilane and β-glycidoxypropylmethyldimethoxysilane; methacryloxysilanes such as γ-methacryloxypropyltrimethoxysilane and γ-methacryloxypropylmethyldimethoxysilane; and mercaptosilanes such as γ-mercaptopropyltrimethoxysilane (3-mercaptopropyltrimethoxysilane).

[0058] 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 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.

[0059] The filler is preferably silica. The content of the filler is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and preferably 50 parts by mass or less, more preferably 30 parts by mass or less, per 100 parts by mass of the total content of the urethane (meth)acrylate oligomer and the vinyl monomer. By setting the content of the filler within the above range, it is possible to suppress an increase in the viscosity of the photocurable composition while ensuring the mechanical strength of a molded article obtained by curing the photocurable composition.

[0060] 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 100 mPa·s or more, more preferably 500 mPa·s or more, even more preferably 1,000 mPa·s or more, and preferably 6,000 mPa·s or less, more preferably 3,000 mPa·s or less, and even more preferably 1,500 mPa·s or less. When the viscosity of the photocurable composition is within the above 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 the above range, workability is good.

[0061] The photocurable composition of the present invention can be suitably used for stereolithography.

[0062] <Method of manufacturing molded body> The method for producing a molded article of the present invention is characterized in that the photocurable composition of the present invention is irradiated with light to cure it and form a three-dimensional shape.

[0063] 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).

[0064] The molded article of the present invention is preferably produced by a method for producing a three-dimensional molded article (stereolithography) by repeating the steps of supplying the photocurable composition of the present invention onto a modeling table, irradiating the photocurable composition with light, and curing the photocurable composition to form a first-layer cured product, supplying a photocurable composition that forms a second-layer cured product on the first-layer cured product, irradiating the photocurable composition with light, and curing the photocurable composition to form a second-layer cured product, and forming up to N layers, similar to the step of forming the second-layer cured product. A known 3D printer can be used for the stereolithography method, and commercially available 3D printers can also be used.

[0065] 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 to 30°C).

[0066] 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.

[0067] (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.

[0068] When the photocurable composition of the present invention is cured, a cured product and a molded article having a low glass transition temperature (Tg) are obtained. The glass transition temperature (Tg) of the cured product and the molded article of the photocurable composition of the present invention is preferably −70° C. or higher, more preferably −60° C. or higher, and even more preferably −50° C. or higher, and is preferably 20° C. or lower, more preferably 10° C. or lower, and even more preferably 0° C. or lower. When the glass transition temperature (Tg) of the cured product and the molded article of the photocurable composition is within the above range, the cured product and the molded article obtained by curing can be endowed with mechanical strength and elasticity.

[0069] The cured product and molded article of the present invention preferably have rubber elasticity as a mechanical property. The cured product and molded article of the present invention preferably have the following mechanical properties, for example.

[0070] The hardness of the cured product and molded article of the present invention is preferably 10 or more, more preferably 20 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 can serve as a substitute for the required rubber elasticity.

[0071] The tensile strength at break of the cured product and molded article of the present invention is preferably 0.5 MPa or more, more preferably 1 MPa or more, even more preferably 2 MPa or more, and preferably 30 MPa or less, more preferably 25 MPa or less, and even more preferably 20 MPa or less, because if the tensile strength at break of the cured product and molded article of the present invention is within the above range, they will serve as a substitute for the required rubber elasticity.

[0072] The tensile breaking elongation of the cured product and molded article of the present invention is preferably 100% or more, more preferably 150% or more, and even more preferably 200% or more, because when the tensile breaking elongation 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.

[0073] The compression set of the cured product and molded article of the present invention is preferably 5% or less, more preferably 3% or less, and even more preferably 1% or less, because if the compression set of the cured product and molded article of the present invention is within this range, they can serve as a substitute for the required rubber elasticity.

[0074] The cyclic fatigue (cycles / mm) of the cured product and molded article of the present invention is preferably 5000 or more, more preferably 6000 or more, and even more preferably 7000 or more, because if the cyclic fatigue of the cured product and molded article of the present invention is within the above range, they will function as a substitute for the required rubber elasticity. [Example]

[0075] 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.

[0076] 1. Evaluation Method (Viscosity of Photocurable Composition) The photocurable composition was measured at a temperature of 25°C (with an error of ±2°C) and a relative humidity of 50% using an E-type viscometer (MCR301 manufactured by Anton-Paar) with a cone plate of φ25 mm and a shear rate of 100 seconds. -1 The viscosity was measured under the following conditions.

[0077] (Glass transition temperature Tg of cured product (molded product)) The glass transition temperature Tg of the cured product (molded product) obtained by curing the photocurable composition was measured using a differential scanning calorimeter (DSC7000X manufactured by Hitachi High-Tech Science Corporation) in accordance with the method specified in JIS K6240:2011.

[0078] (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.

[0079] (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.

[0080] (Compression set) The cured product (molded product) obtained by curing the photocurable composition (shaped like a compressed ball of φ29 × 12.5 mm as specified in JIS K6262:2013) was compressed by 25% for 22 hours at 23°C in accordance with the provisions of JIS K6262:2013, and the compression set was measured 0.5 hours after the compression was released. The smaller the compression set value, the better the recovery force of the cured product (molded product).

[0081] (cyclic fatigue test) The photocurable composition was cured to obtain a cured product (molded article) (JIS K6260:2017 test piece (dimensions: length 150 mm, width 25 mm, radius of curvature of the central groove 2.38 mm, thickness 6.3 mm)) and subjected to a cyclic fatigue test using a de Mattia flexural tester in accordance with the JIS K6260:2017 standard. A notch was made in the central groove of the test piece, and the degree of crack growth was measured when the specimen was repeatedly flexed at 5 Hz and with a strain of 50% on the central groove. The crack growth rate (cycles / mm) was calculated using the following formula: The number of flexions required for the crack to grow 1 mm was counted. The higher the value, the longer it took for the crack to grow 1 mm, and the cyclic fatigue test results (flexural crack growth resistance) were deemed good. Crack growth rate (times / mm) = number of flexions (times) / crack length (mm)

[0082] 2. Preparation of photocurable composition Photocurable compositions were prepared using the following materials in the blending ratios (parts by mass) shown in Tables 1 and 2, by mixing and degassing using a stirrer capable of rotation and revolution. The viscosity of the prepared photocurable compositions was measured, and the results are shown in Tables 1 and 2. Each component was mixed so that it was homogeneous. In Tables 1 and 2, "-" indicates that the component was not blended.

[0083] The materials used in Tables 1 and 2 are as follows: Urethane (meth)acrylate oligomer 1: EBECRYL230 (aliphatic urethane acrylate oligomer, number average molecular weight: 5,000, viscosity at 25°C: 40,000 mPa·s, glass transition temperature: -55°C) manufactured by Daicel Allnex Co., Ltd. Urethane (meth)acrylate oligomer 2: EBECRYL9270 (aliphatic urethane acrylate oligomer (low viscosity type), number average molecular weight: 1,000, viscosity at 25°C: 7,500 mPa·s, glass transition temperature: 2°C) manufactured by Daicel Allnex Co., Ltd. Second 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, Ltd. First Monomer A: 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) First monomer B: 2-ethylhexyl acrylate manufactured by Tokyo Chemical Industry Co., Ltd. (molecular weight: 184.3, viscosity at 25°C: 3 mPa·s, glass transition temperature: -70°C) Photopolymerization initiator 1: BASF Omnirad819 (acylphosphine oxide photopolymerization initiator, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, molecular weight: 418.5) Photopolymerization initiator 2: BASF Omnirad 1173 (alkylphenone photopolymerization initiator, 2-hydroxy-2-methylpropiophenone, molecular weight: 164.2, viscosity at 25°C: 25 mPa·s) Silica: Nipsil KQ manufactured by Tosoh Corporation (amorphous silicon dioxide, primary particle size 14 nm, BET specific surface area 220 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.

[0084] [Table 1]

[0085] [Table 2]

[0086] 3. Manufacturing of molded bodies 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 0.05 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 dumbbell-shaped No. 3 test piece according to JIS K6251:2017 used in the tensile test described above. The second was the shape of a φ29 x 12.5 mm compression ball according to JIS K6262:2013 used in the hardness and compression set measurements described above. The third was the JIS K6260:2017 test piece (dimensions: length 150 mm, width 25 mm, radius of curvature of the central groove 2.38 mm, thickness 6.3 mm) used in the cyclic fatigue test described above.

[0087] The obtained molded article was subjected to measurements of hardness, tensile strength at break, tensile elongation at break, compression set, and repeated fatigue test. The results are shown in Tables 1 and 2.

[0088] The results in Tables 1 and 2 show that the photocurable composition of the present invention, which contains a urethane (meth)acrylate oligomer and a vinyl monomer, a first monomer having a glass transition temperature (Tg) of -100°C or higher but 20°C or lower and a second monomer having a glass transition temperature (Tg) of more than 20°C but 150°C or lower, in which the content of the urethane (meth)acrylate oligomer is 20% to 80% by mass, the content of the first monomer is 15% to 75% by mass, and the content of the second monomer is 5% to 65% by mass, and the total content of the urethane (meth)acrylate oligomer and vinyl monomer is 100% by mass, produces molded articles with excellent mechanical properties. It can be seen that the photocurable composition of the present invention is suitable for use in stereolithography.

[0089] Due to its high viscosity, photocurable composition No. 17 could not be molded into a molded product under the above conditions. Therefore, we lowered the apparent viscosity by increasing the temperature of the composition liquid to 40-80°C, and we also increased the stage lift distance to approximately 10 times the normal distance when creating one layer, allowing layers to be formed at 1 / 10 the normal speed. However, it is difficult to produce a molded product using such conditions when using a commercially available 3D printer. Furthermore, since the upper temperature limit of commercially available 3D printers is approximately 30°C, it is difficult to stereolithograph photocurable composition No. 17 using a commercially available 3D printer. [Industrial Applicability]

[0090] The photocurable composition of the present invention is suitable for use in stereolithography.

[0091] The photocurable composition of the present invention (1) contains 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.

[0092] The present invention (2) is the photocurable composition according to the present invention (1), wherein the urethane (meth)acrylate oligomer has a (meth)acryloyl group.

[0093] The present invention (3) is the photocurable composition according to the present invention (1) or (2), wherein the glass transition temperature (Tg) of the urethane (meth)acrylate oligomer is -100°C to 50°C.

[0094] The present invention (4) is the photocurable composition according to any one of the present inventions (1) to (3), 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.

[0095] The present invention (5) is the photocurable composition according to any one of the present inventions (1) to (4), wherein the vinyl monomer contains a (meth)acrylate.

[0096] The present invention (6) is the photocurable composition according to any one of the present inventions (1) to (5), which contains 2-ethylhexyl acrylate and / or (2-methyl-2-ethyl-1,3-dioxolan-4-yl) methacrylate as the first monomer.

[0097] The present invention (7) is the photocurable composition according to any one of the present inventions (1) to (6), which contains isobornyl acrylate as the second monomer.

[0098] The present invention (8) is a viscosity (temperature 25°C, shear rate 100 sec -1 ) is 6,000 mPa·s or less.

[0099] The present invention (9) is the photocurable composition according to any one of the present inventions (1) to (8), which is used for stereolithography.

[0100] The present invention (10) is a cured product of the photocurable composition according to any one of the present inventions (1) to (9), which has a glass transition temperature (Tg) of 20° C. or lower.

[0101] The present invention (11) is a molded article obtained by curing the photocurable composition according to any one of the present inventions (1) to (9).

[0102] The present invention (12) is a method for producing a molded article, characterized in that the photocurable composition according to any one of the present inventions (1) to (9) is irradiated with light to cure the composition and form a three-dimensional shape.

Claims

1. a urethane (meth)acrylate oligomer; A photocurable composition containing, as vinyl monomers, a first monomer having a glass transition temperature (Tg) of -100°C or more and 20°C or less, and a second monomer having a glass transition temperature (Tg) of more than 20°C and 150°C or less, the viscosity of the photocurable composition (at 25°C and a shear rate of 100 sec-1) is 500 mPa·s or more and 6,000 mPa·s or less; the compression set of the cured product of the photocurable composition is 5% or less; the first monomer comprises (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate; 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, A photocurable composition comprising a urethane (meth)acrylate oligomer and a vinyl monomer in a total content of 100 mass %.

2. 2. The photocurable composition according to claim 1, wherein the urethane (meth)acrylate oligomer has two or more (meth)acryloyl groups in the molecule.

3. 2. 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.

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

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

6. A photocurable composition as described in claim 1, wherein the content of the urethane (meth)acrylate oligomer is in the range of 35% by mass to 80% by mass.

7. The photocurable composition according to claim 1 , wherein the second monomer is isobornyl acrylate.

8. The photocurable composition according to claim 1, wherein the glass transition temperature (Tg) of the urethane (meth)acrylate oligomer is -100°C to 10°C.

9. The photocurable composition according to claim 1, which is used for stereolithography.

10. A cured product of the photocurable composition according to any one of claims 1 to 9, having a glass transition temperature (Tg) of 20°C or lower.

11. A molded article obtained by curing the photocurable composition according to any one of claims 1 to 9.

12. A method for producing a molded article, comprising irradiating the photocurable composition according to any one of claims 1 to 9 with light to cure the composition and form a three-dimensional shape.

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