Photocurable composition and molded article thereof

Abstract

To provide a photocurable composition from which a shaped product having excellent mechanical properties is obtained.SOLUTION: A photocurable composition comprises: a urethane (meth)acrylate oligomer; vinyl monomers consisting of a first monomer with a glass transition temperature (Tg1) of -100°C or more and 10°C or less and a second monomer with a glass transition temperature (Tg2) of 70°C or more and 150°C or less; and carbon nanotubes, wherein the photocurable composition comprises the carbon nanotubes in an amount of 0.01 to 0.35 pts.mass with respect to 100 pts.mass of the total combined amount 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 in stereolithography. [Background technology]

[0002] In recent years, three-dimensional additive manufacturing equipment (so-called 3D printers) that manufacture three-dimensional structures by layering and curing resin based on design data for three-dimensional structures have been put into practical use. Among the three-dimensional structures manufactured by three-dimensional additive manufacturing equipment, those made of resin are generally well known.

[0003] For example, Patent Document 1 discloses a rubber composition for three-dimensional additive manufacturing containing liquid rubber, and this rubber composition can be applied to a three-dimensional additive manufacturing apparatus to suitably produce an elastic molded body.

[0004] Patent Document 2 describes a polymer composition for photopolymerization comprising a liquid polymer and a monomer, wherein the photopolymerization polymer composition was tested using an E-type viscometer at a temperature of 25°C and a relative humidity of 50%, with a cone plate diameter of φ25 mm and a shear rate of 100 seconds. -1 A polymer composition for photopolymerization is disclosed, having a viscosity of 3,000 mPa·s or less as measured under the specified conditions. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] International Publication No. 2017 / 154335 [Patent Document 2] Japanese Patent Publication No. 2021-75044 [Overview of the project] [Problems that the invention aims to solve]

[0006] The mechanical properties of cured products from conventional photocurable compositions used in stereolithography are not satisfactory. This invention has been made in view of the above circumstances, and aims to provide a photocurable composition that exhibits excellent mechanical properties in molded articles. [Means for solving the problem]

[0007] The photocurable composition of the present invention contains a urethane (meth)acrylate oligomer, a vinyl monomer consisting of 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, and carbon nanotubes, characterized in that it contains 0.01 parts by mass to 0.35 parts by mass of carbon nanotubes per 100 parts by mass of the total content of urethane (meth)acrylate oligomer and vinyl monomer. [Effects of the Invention]

[0008] The photocurable composition of the present invention can be suitably used for stereolithography. Molded articles formed from the photocurable composition of the present invention exhibit excellent mechanical properties. [Modes for carrying out the invention]

[0009] <Photocurable composition> The photocurable composition of the present invention contains a urethane (meth)acrylate oligomer, a vinyl monomer consisting of 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, and carbon nanotubes, characterized in that it contains 0.01 parts by mass to 0.35 parts by mass of carbon nanotubes per 100 parts by mass of the total content of urethane (meth)acrylate oligomer and vinyl monomer.

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

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

[0012] The urethane prepolymer is preferably formed by the reaction of a polyisocyanate and a polyol. Urethane bonds are formed in the molecular chains of the urethane prepolymer by the reaction of the polyisocyanate and the polyol. The urethane prepolymer has an isocyanate group or a hydroxyl group at the end of its molecular chain. The urethane prepolymer may also have an amino group at the end of its molecular chain.

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

[0014] Examples of polyol components that make up urethane (meth)acrylate oligomers include low molecular weight polyols with a molecular weight of less than 500 and high molecular weight polyols with a number average molecular weight of 500 or more.

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

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

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

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

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

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

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

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

[0023] Examples of polyisocyanate components that can constitute the urethane (meth)acrylate oligomer include compounds having at least two isocyanate groups. Examples of the polyisocyanates 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'-vitrylene-4,4'-diisocyanate (TODI), xylylene diisocyanate (XDI), tetramethyl xylylene diisocyanate (TMXDI), and paraphenylenedi diisocyanate (PPDI); and 4,4'-dicyclohexylmethane diisocyanate (H 12 Examples include alicyclic polyisocyanates or aliphatic polyisocyanates such as MDI, hydrogenated xylylene diisocyanate (H6XDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), norbornene diisocyanate (NBDI); and derivatives of these polyisocyanates. In the present invention, two or more polyisocyanates may be used as the polyisocyanate.

[0024] Examples of the polyisocyanate derivatives include adduct-modified compounds obtained by reacting diisocyanate with a polyhydric alcohol; isocyanurate-modified compounds of diisocyanate; biuret-modified compounds; and alohanate-modified compounds, with those from which free diisocyanate has been removed being more preferable.

[0025] The adduct-modified product is a polyisocyanate obtained by reacting a diisocyanate with a polyhydric alcohol. The polyhydric alcohol is preferably a low molecular weight triol such as trimethylolpropane or glycerin. The adduct-modified product is preferably, for example, a triisocyanate obtained by reacting a diisocyanate with trimethylolpropane; or a triisocyanate obtained by reacting a diisocyanate with glycerin.

[0026] The aforementioned allohanate 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 diisocyanate with the urethane bond.

[0027] By reacting a urethane prepolymer having isocyanate groups at the ends of its molecular chains with a (meth)acrylate having a hydroxyl group, a urethane (meth)acrylic oligomer having a (meth)acryloyl group can be obtained. Examples of (meth)acrylates having a hydroxyl group include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.

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

[0029] Examples of urethane (meth)acrylate oligomers include aliphatic urethane (meth)acrylate oligomers and aromatic urethane (meth)acrylate oligomers. An aliphatic urethane (meth)acrylate oligomer is one in which the constituent components of the urethane (meth)acrylate oligomer are aliphatic compounds. For example, this is the case when aliphatic polyisocyanates are used as constituent components. An aromatic urethane (meth)acrylate oligomer is one in which the constituent components of the urethane (meth)acrylate oligomer are aromatic compounds. For example, this is the case when aromatic polyisocyanates are used as constituent components.

[0030] The glass transition temperature (Tg) of the urethane (meth)acrylate oligomer is not particularly limited, but is preferably -100°C or higher, more preferably -90°C or higher, even more preferably -80°C or higher, 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. If the glass transition temperature of the urethane (meth)acrylate oligomer is within the above range, it is possible to achieve mechanical strength while suppressing the rise in the glass transition temperature (Tg) of the molded article obtained by curing the photocurable composition.

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

[0032] The number-average molecular weight of the urethane (meth)acrylate oligomer is preferably 300 or more, more preferably 1000 or more, even more preferably 3000 or more, preferably 30000 or less, more preferably 20000 or less, and even more preferably 15000 or less. If the number-average molecular weight of the urethane (meth)acrylate oligomer is within the above range, the workability in photopolymerization is good, and the curing shrinkage rate and mechanical strength of the molded article obtained by curing the photocurable composition are superior.

[0033] When the total content of urethane (meth)acrylate oligomer and vinyl monomer is set to 100% by mass, the content of urethane (meth)acrylate oligomer is preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 35% by mass or more, preferably 80% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less.

[0034] If the urethane (meth)acrylate oligomer content is 80% by mass or less, the viscosity of the photocurable composition will not be too high, making stereolithography easier. Furthermore, if the urethane (meth)acrylate oligomer content is 20% by mass or more, the mechanical strength of the molded article obtained by curing the photocurable composition will not decrease.

[0035] The content of the urethane (meth)acrylate oligomer is preferably selected from the above range such that the total content of the urethane (meth)acrylate oligomer and vinyl monomer is 100% by mass.

[0036] 2. Vinyl monomer In the present invention, "vinyl monomer" refers to a monomer having a carbon-carbon double bond in its molecule that is capable of radical polymerization. Preferably, the vinyl monomer contains a first monomer having a homopolymer glass transition temperature (Tg1) of -100°C or higher and 10°C or lower, and a second monomer having a homopolymer glass transition temperature (Tg2) of 70°C or higher and 150°C or lower. By containing a first monomer with a low glass transition temperature and a second monomer with a high glass transition temperature, the molded article obtained by curing the photocurable composition has excellent mechanical properties.

[0037] 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, preferably 10°C or lower, more preferably 5°C or lower, even more preferably 0°C or lower, and particularly preferably -5°C or lower.

[0038] 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, preferably 150°C or lower, more preferably 130°C or lower, and even more preferably 110°C or lower.

[0039] The difference between the glass transition temperature (Tg2) of the second monomer and the glass transition temperature (Tg1) of the first monomer (Tg2-Tg1) 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, preferably 250°C or lower, more preferably 200°C or lower, even more preferably 150°C or lower, and particularly preferably 120°C or lower.

[0040] When the total content of urethane (meth)acrylate oligomer and 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, 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, it is possible to lower the glass transition temperature (Tg) of the molded article obtained by curing the photocurable composition while obtaining mechanical strength.

[0041] When the total content of urethane (meth)acrylate oligomer and vinyl monomer is 100% by mass, the content of the second monomer is preferably 5% by mass or more, more preferably 8% by mass or more, even more preferably 10% by mass or more, preferably 65% ​​by mass or less, more preferably 50% by mass or less, and even more preferably 30% by mass or less. If the content of the second monomer is within the above range, the molded article obtained by curing the photocurable composition can have mechanical strength while suppressing the rise in glass transition temperature (Tg).

[0042] The content of the first monomer and the content of the second monomer are preferably selected from the above range such that the total content of urethane (meth)acrylate oligomer and vinyl monomer is 100% by mass.

[0043] The mass ratio of the first monomer to the second monomer (first monomer / second monomer) is preferably 0.5 or higher, more preferably 1.0 or higher, even more preferably 2.0 or higher, preferably 15 or lower, more preferably 10 or lower, and even more preferably 5 or lower. If the mass ratio (first monomer / second monomer) is within the above range, the effects of the present invention can be obtained more favorably.

[0044] Specific examples of vinyl monomers include aromatic vinyl monomers, vinyl monomers having hydroxyl groups, vinyl monomers having carboxyl groups, vinyl monomers having sulfonic acid groups, vinyl monomers having phosphate groups, vinyl monomers containing tertiary amines, vinyl monomers containing quaternary ammonium bases, vinyl monomers containing heterocycles, vinyl amides, vinyl monomers containing epoxy groups, vinyl carboxylates, α-olefins, dienes, (meth)acrylic monomers, and the like.

[0045] Examples of the vinyl monomer include monofunctional monomers and polyfunctional monomers (e.g., difunctional monomers, trifunctional monomers, tetrafunctional monomers, etc.). From the viewpoint of achieving a viscosity suitable for stereolithography while exhibiting excellent properties in the elastic molded article obtained by curing, monofunctional to tetrafunctional monomers are preferred. The use of monofunctional monomers is preferred from the viewpoint of reducing the viscosity of the photocurable composition at room temperature. The use of polyfunctional monomers is preferred from the viewpoint of exhibiting excellent properties in the molded article.

[0046] The vinyl monomer preferably contains (meth)acrylate because it has a viscosity suitable for stereolithography while exhibiting excellent photocuring reactivity.

[0047] Preferred monofunctional monomers include monofunctional (meth)acrylates. Specific examples of 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, and 3-(2-phenyl (Phenyl)-2-hydroxypropyl (meth)acrylate, (meth)acrylate of p-cumylphenol obtained by reacting with ethylene oxide, 2-bromophenoxyethyl (meth)acrylate, 2,4-dibromophenoxyethyl (meth)acrylate, 2,4,6-tribromophenoxyethyl (meth)acrylate, phenoxy(meth)acrylate obtained by molar modification of ethylene oxide or propylene oxide, isobornyl (meth)acrylate, bornyl (meth)acrylate, 2-methyl-2-ethyl-1,3-Dioxolan-4-yl)methyl (meth)acrylate, tricyclodecanyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, cyclohexyl (meth)acrylate, 4-butylcyclohexyl (meth)acrylate, acryloylmorpholine, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate t-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, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate Rate, 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,N-diethyl (meth)acrylamide, N,Examples include 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 (e.g., N-vinylpyrrolidone, N-vinylcaprolactam, vinylimidazole, vinylpyridine, etc.).

[0048] Furthermore, 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 include propanetrioxyethyl (meth)acrylate, tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, tris(acryloyloxy)isocyanurate, bis(hydroxymethyl)tricyclodecane di(meth)acrylate, dipentaerythritol hexa(meth)acrylate, di(meth)acrylate of diols which are adducts of bisphenol A to polyethylene oxide or propylene oxide, di(meth)acrylate of diols which are adducts of hydrogenated bisphenol A to ethylene oxide or propylene oxide, epoxy(meth)acrylate obtained by adding (meth)acrylate to diglycidyl ether of bisphenol A, and triethylene glycol divinyl ether.

[0049] As the glass transition temperature (Tg) of the vinyl monomer, for example, the glass transition temperature disclosed on the following website can be taken into consideration. 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 /

[0050] Examples of first monomers with 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), and 2-hydroxypropyl acrylate (-7°C). Examples include 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), and (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate (-7°C).

[0051] Examples of secondary monomers with 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).

[0052] 3. Carbon nanotubes Carbon nanotubes (CNTs) are carbon materials in which, for example, graphene sheets are wound to form a hollow tubular structure. Examples of carbon nanotubes include single-walled carbon nanotubes (SWCNTs) consisting of a single graphene sheet, and multi-walled carbon nanotubes (MWCNTs) consisting of two or three or more graphene sheets. These can be used individually or in combination of two or more types. In the present invention, it is preferable that the carbon nanotubes include single-walled carbon nanotubes.

[0053] The carbon nanotube content is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, even more preferably 0.10 parts by mass or more, preferably 0.35 parts by mass or less, more preferably 0.30 parts by mass or less, and even more preferably 0.25 parts by mass or less, based on 100 parts by mass of the total content of urethane (meth)acrylate oligomer and vinyl monomer. If the carbon nanotube content is 0.01 parts by mass or more, the mechanical properties of the molded article obtained by curing the photocurable composition are improved, and if it is 0.35 parts by mass or less, the increase in viscosity of the photocurable composition is suppressed, making it easier to shape the molded article.

[0054] 4. Other ingredients The photocurable composition of the present invention preferably contains a photopolymerization initiator. The inclusion of a photopolymerization initiator can accelerate the curing of the aforementioned photocurable composition. The photopolymerization initiator is not particularly limited; known initiators that generate radicals upon light irradiation can be used.

[0055] Examples of the photopolymerization initiators include alkylphenones such as 2-hydroxy-2-methylpropiophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenyl 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; Acyl phosphine 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-benzoyl oxime)), and ethanone, 1-(9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl)-,1-(O-acetyl oxime).

[0056] In stereolithography, light sources with peak wavelengths in the range of 390 nm to 410 nm, particularly those with peak wavelengths at 405 nm, are mainly used. It is preferable to initiate the 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 types.

[0057] In photopolymerization using the light source described above, from the viewpoint of suitably curing the photocurable composition, the photocurable composition of the present invention preferably contains at least two types of photopolymerization initiators with different absorption bands. For example, it is preferable to use in combination 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 the present invention, it is preferable to use in combination an alkylphenone-based photopolymerization initiator and an acylphosphine oxide-based photopolymerization initiator as the photopolymerization initiator.

[0058] The content of the photopolymerization initiator is preferably 1 part by mass or more, more preferably 1.5 parts by mass or more, even more preferably 2 parts by mass or more, 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, based on the total content of urethane (meth)acrylate oligomer and vinyl monomer per 100 parts by mass.

[0059] When using an alkylphenone-based photopolymerization initiator and an acylphosphine oxide-based photopolymerization initiator in combination, the mass ratio of these (alkylphenone-based / acylphosphine oxide-based) is preferably 0.2 or higher, more preferably 0.5 or higher, even more preferably 0.8 or higher, preferably 5 or lower, more preferably 3 or lower, and even more preferably 2 or lower.

[0060] The photocurable composition of the present invention may further contain various additives as long as they do not impair the effects of the present invention. Examples of additives include silane coupling agents, diluent polymers, photosensitizers, fillers (excluding carbon nanotubes), UV blocking agents, dyes, pigments, leveling agents, fluidity modifiers, defoaming agents, plasticizers, polymerization inhibitors, flame retardants, dispersion stabilizers, preservation stabilizers, antioxidants, metals, metal oxides, metal salts, and ceramics. The photocurable composition may contain one or more additives.

[0061] Silica is preferred as the filler. The filler content is preferably 1 part by mass or more, more preferably 5 parts by mass or more, preferably 50 parts by mass or less, and more preferably 30 parts by mass or less, based on 100 parts by mass of the total content of urethane (meth)acrylate oligomer and vinyl monomer. By setting the filler content within the above range, it is possible to achieve the mechanical strength of the molded article obtained by curing the photocurable composition while suppressing an increase in the viscosity of the photocurable composition.

[0062] The silane coupling agent is not particularly limited, but examples 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).

[0063] The photocurable composition of the present invention can be easily produced by mixing a urethane (meth)acrylate oligomer, a vinyl monomer, carbon nanotubes, and, if necessary, a photopolymerization initiator and various additives.

[0064] The photocurable composition of the present invention was tested using an E-type viscometer at a temperature of 25°C and a relative humidity of 50%, with a cone plate diameter of φ25 mm and a shear rate of 100 seconds. -1 The viscosity measured under these conditions is preferably 1,000 mPa·s or more, more preferably 1,500 mPa·s or more, even more preferably 2,000 mPa·s or more, preferably 6,000 mPa·s or less, more preferably 5,500 mPa·s or less, and even more preferably 5,000 mPa·s or less. If the viscosity of the photocurable composition is within the above range, it is possible to impart elasticity to the molded article obtained by curing while maintaining a viscosity suitable for stereolithography at room temperature. Furthermore, if the viscosity of the photocurable composition is within the above range, the workability is good.

[0065] The photocurable composition of the present invention can be suitably used for stereolithography.

[0066] <Method for manufacturing three-dimensional objects using stereolithography> The present invention includes a method for manufacturing a three-dimensional object by stereolithography using the photocurable composition of the present invention. Preferably, the method for manufacturing a three-dimensional object by stereolithography of the present invention comprises the steps of curing the photocurable composition of the present invention by irradiating it with light and forming the cured photocurable composition into a three-dimensional shape. In the present invention, a three-dimensional object manufactured by stereolithography may be simply referred to as a "molded body".

[0067] As a method for manufacturing the molded article of the present invention, various stereolithography methods such as SLA (Stereolithography Appratus), DLP (Digital Light Processing), and LCD (Liquid Crystal Display) can be employed.

[0068] The method for manufacturing a three-dimensional object using the stereolithography method of the present invention preferably comprises, for example, the following steps 1 to N.

[0069] In the first step, the photocurable composition of the present invention is supplied onto the build plate, and light is irradiated onto the photocurable composition to cure it and form a first layer consisting of a cured material. Preferably, the photocurable composition is supplied in layers onto the build plate. The photocurable composition only needs to be applied to the position on the build plate corresponding to the final three-dimensional shape, and does not necessarily need to be applied to the entire surface of the build plate.

[0070] In the second step, a photocurable composition is supplied onto the cured first layer, and the photocurable composition is irradiated with light to cure it, thereby forming a second layer consisting of the cured material. Preferably, the photocurable composition is supplied in layers on the first layer. The photocurable composition only needs to be applied to the position on the first layer corresponding to the final three-dimensional shape, and does not necessarily need to be applied to the entire surface of the first layer.

[0071] It is preferable to repeat the above second step up to the Nth step (where N is a natural number of 3 or more). In the Nth step, a photocurable composition is supplied onto the cured material of the (N-1)th layer, and the photocurable composition is irradiated with light to cure the photocurable composition and form the Nth layer consisting of the cured material. It is preferable that the photocurable composition is supplied in layers on the (N-1)th layer. The photocurable composition only needs to be applied to a position on the (N-1)th layer corresponding to the final three-dimensional shape, and does not necessarily need to be applied to the entire surface of the (N-1)th layer.

[0072] By performing steps 1 through N, the photocurable composition is formed into a three-dimensional object in which the cured material is layered.

[0073] In the method for manufacturing a three-dimensional object using the stereolithography method of the present invention, it is preferable to use a known 3D printer. A commercially available 3D printer can be used as the 3D printer.

[0074] In stereolithography, the thickness of a single layer when curing the photocurable composition is preferably about 0.01 mm to 0.5 mm. The irradiated light is generally ultraviolet light, preferably including light with a wavelength of 405 nm. The irradiated light intensity is 0.1 mW / cm² in the measurement wavelength range of 405 nm. 2 ~100mW / cm 2 A certain degree is preferable. The light irradiation time when curing a single layer of photocurable composition varies depending on the stereolithography method and should be adjusted as appropriate. For example, in the DLP method, it is about 1 to 60 seconds. The molded articles of the present invention are preferably manufactured in an environment of room temperature (e.g., 20°C to 30°C).

[0075] Furthermore, after the stereolithography process described above, additional 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 of the fabricated object, improve its strength, or accelerate hardening. While these secondary treatments are not always necessary and may not be required depending on the stereolithography conditions, they can be performed in conjunction with the stereolithography process.

[0076] <Molded articles and cured products> The present invention includes cured products and molded articles obtained by curing the photocurable composition of the present invention.

[0077] 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.

[0078] The hardness of the cured product and molded article of the present invention is preferably 20 or higher, more preferably 25 or higher, even more preferably 30 or higher, preferably 100 or lower, more preferably 80 or lower, and even more preferably 70 or lower, on a Shore A hardness scale. This is because if the hardness of the cured product and molded article of the present invention falls within the above range, it can serve as a substitute for the rubber elasticity required.

[0079] The tensile breaking strength of the cured product and molded article of the present invention is preferably 2.0 MPa or higher, more preferably 3.0 MPa or higher, and even more preferably 4.0 MPa or higher. This is because if the tensile breaking strength of the cured product and molded article of the present invention is within the above range, it can serve as a substitute for the rubber elasticity required. The upper limit of the tensile breaking strength is not particularly limited, but is usually 50.0 MPa.

[0080] The tensile elongation at break of the cured product and molded article of the present invention is preferably 280% or more, more preferably 290% or more, and even more preferably 300% 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 can serve as a substitute for the rubber elasticity required. The upper limit of the tensile elongation at break is not particularly limited, but is usually 500%.

[0081] The aforementioned physical properties are values ​​measured by the method described below. [Examples]

[0082] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples, and any modifications and embodiments that do not depart from the spirit of the present invention are all included within the scope of the present invention.

[0083] 1. Evaluation Method (Viscosity of photocurable composition) For the photocurable composition, under conditions of 25°C (with an error of ±2°C) and 50% relative humidity, an E-type viscometer (MCR301 manufactured by Anton-Paar) was used with a φ25mm cone plate and a shear rate of 100 seconds. -1 The viscosity was measured under the following conditions.

[0084] (Hardness of the cured product (molded body)) The Shore A hardness of the cured product (molded body) obtained by curing the photocurable composition (in the shape of a compressed ball with a diameter of φ29 × 12.5 mm as specified in JIS K6262:2013) was measured in accordance with the method specified in JIS K6253-3:2012.

[0085] (Tensile test of cured material (molded body)) The tensile breaking strength and tensile elongation were measured for the cured product (molded body) obtained by curing the photocurable composition (in the shape of a dumbbell-shaped test specimen No. 3 according to JIS K6251:2017) in accordance with the provisions of JIS K6251:2017. A higher tensile breaking strength indicates higher strength of the cured product (molded body), and a higher tensile elongation indicates greater elongation, indicating good mechanical properties of the cured product (molded body).

[0086] 2. Manufacture of photocurable compositions Using the following materials, a photocurable composition was prepared by mixing and degassing in a rotary and orbiting stirrer to the proportions (parts by mass) shown in Table 1. The viscosity of the prepared photocurable composition was measured and the results are shown in Table 1. Each component was mixed to ensure uniformity. In Table 1, "-" indicates that the component was not included.

[0087] The following materials were used as shown in Table 1. • Urethane (meth)acrylate oligomer: Arkema CN8899NS (aliphatic urethane acrylate oligomer, viscosity at 60°C: 25000 mPa·s-35000 mPa·s, glass transition temperature: -80°C) • Vinyl monomer 1: 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) • Second 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. • Carbon nanotube 1: OCSiAl TUBALL (single-walled carbon nanotube, average outer diameter: 1.6 ± 0.4 nm, length: 5 μm or more, surface area: 300 m²) 2 / g or more, G / D ratio: 90 or more) • Carbon nanotube 2: Manufactured by Fujifilm Wako Chemical Co., Ltd. (Multiwall carbon nanotube, diameter: 20-30 nm, CAS registry number: 308068-56-6) • Photopolymerization initiator 1: Omnirad 819 (acyl phosphine oxide type photopolymerization initiator, phenylbis(2,4,6-trimethylbenzoyl) phosphine oxide, molecular weight: 418.5) manufactured by IGM Resins BV. • Photopolymerization initiator 2: Omnirad 1173 (alkylphenone-based photopolymerization initiator, 2-hydroxy-2-methylpropiophenone, molecular weight: 164.2, viscosity at 25°C: 25 mPa·s) manufactured by IGM Resins BV.

[0088] [Table 1]

[0089] 3. Manufacturing of molded products (objects with three-dimensional shapes) A photocurable composition was used to fabricate a molded body using DLP (Digital Light Purification) stereolithography. Specifically, a 3D printer equipped with a light source (UV-LED) with a peak wavelength of 405 nm was used, with a temperature of 23°C, a layer thickness of 0.05 mm, an irradiation time of 20 seconds per layer, and an illuminance of 5.0 mW / cm² at a wavelength of 405 nm. 2 The molded bodies were created under the specified conditions. Two different shapes were produced for each type of molded body. The first was the shape of the φ29×12.5mm test specimen according to JIS K6262:2013, which was used in the hardness measurement mentioned above, and the second was the shape of the dumbbell-shaped No. 3 test specimen according to JIS K6251:2017, which was used in the tensile test mentioned above.

[0090] Table 1 shows the results of measuring the hardness, tensile strength, and tensile elongation of the obtained molded articles.

[0091] The results in Table 1 show that the photocurable composition of the present invention, which contains a urethane (meth)acrylate oligomer, a first monomer with a glass transition temperature (Tg1) of -100°C or higher and 10°C or lower as a vinyl monomer, a second monomer with a glass transition temperature (Tg2) of 70°C or higher and 150°C or lower, and carbon nanotubes, and contains 0.01 to 0.35 parts by mass of carbon nanotubes per 100 parts by mass of the total content of urethane (meth)acrylate oligomer and vinyl monomer, provides a molded article with excellent mechanical properties. It can be seen that the photocurable composition of the present invention is suitable for use in stereolithography. [Industrial applicability]

[0092] The photocurable composition of the present invention is suitable for use in stereolithography.

[0093] A preferred embodiment (1) of the present invention is a photocurable composition containing a urethane (meth)acrylate oligomer, a first monomer having a glass transition temperature (Tg1) of -100°C or higher and 10°C or lower as a vinyl monomer, a second monomer having a glass transition temperature (Tg2) of 70°C or higher and 150°C or lower, and carbon nanotubes, wherein the carbon nanotubes are contained in an amount of 0.01 parts by mass to 0.35 parts by mass per 100 parts by mass of the total content of the urethane (meth)acrylate oligomer and vinyl monomer.

[0094] A preferred embodiment (2) of the present invention is a photocurable composition according to embodiment (1), wherein, when the total content of urethane (meth)acrylate oligomer and vinyl monomer is 100% by mass, 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, and the content of the second monomer is in the range of 5% to 65% by mass.

[0095] A preferred embodiment (3) of the present invention is the photocurable composition according to embodiment (1) or (2), wherein the urethane (meth)acrylate oligomer has a (meth)acryloyl group.

[0096] A preferred embodiment (4) of the present invention is a photocurable composition according to any one of embodiments (1) to (3), 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.

[0097] A preferred embodiment (5) of the present invention is a photocurable composition according to any one of embodiments (1) to (4), wherein the vinyl monomer comprises (meth)acrylate.

[0098] A preferred embodiment (6) of the present invention is a photocurable composition according to any one of embodiments (1) to (5) above, which contains (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methacrylate as the first monomer.

[0099] A preferred embodiment (7) of the present invention is the photocurable composition according to any one of the above embodiments (1) to (6), which contains isobornyl acrylate as the second monomer.

[0100] A preferred embodiment (8) of the present invention is the photocurable composition according to any one of the above embodiments (1) to (7), having a viscosity (at a temperature of 25 °C and a shear rate of 100 s -1 ) of 6,000 mPa·s or less.

[0101] A preferred embodiment (9) of the present invention is the photocurable composition according to any one of the above embodiments (1) to (8), which is for optical molding.

[0102] A preferred embodiment (10) of the present invention is a cured product obtained by curing the photocurable composition according to any one of the above embodiments (1) to (9).

[0103] A preferred embodiment (11) of the present invention is a molded article obtained by producing the photocurable composition according to any one of the above embodiments (1) to (9) by an optical molding method.

[0104] A preferred embodiment (12) of the present invention is a method for producing a three-dimensional shaped object by an optical molding method using the photocurable composition according to any one of the above embodiments (1) to (9).

Claims

1. Urethane (meth)acrylate oligomer and The vinyl monomer contains a first monomer with a glass transition temperature (Tg1) of -100°C or higher and 10°C or lower, a second monomer with a glass transition temperature (Tg2) of 70°C or higher and 150°C or lower, and carbon nanotubes. The vinyl monomer consists solely of monofunctional vinyl monomers. The first monomer contains an acrylate monomer having a heterocycle, When the total content of urethane (meth)acrylate oligomer and vinyl monomer is set to 100% by mass, The content of the urethane (meth)acrylate oligomer is in the range of 20% by mass to 50% 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 characterized by containing 0.01 to 0.35 parts by mass of carbon nanotubes per 100 parts by mass of the total content of urethane (meth)acrylate oligomer and vinyl monomer.

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

3. The photocurable composition according to claim 1, comprising (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate as the first monomer.

4. The photocurable composition according to claim 1, comprising (meth)acrylate as the second monomer.

5. The photocurable composition according to claim 1, comprising isobornyl acrylate as the second monomer.

6. Viscosity (at 25°C, shear rate 100 seconds) －１ The photocurable composition according to claim 1, wherein the pressure is 6,000 mPa·s or less.

7. A photocurable composition according to any one of claims 1 to 6, for use in stereolithography.

8. A cured product obtained by curing the photocurable composition according to any one of claims 1 to 6.

9. A molded article obtained by producing a photocurable composition according to any one of claims 1 to 6 by stereolithography.

10. A method for manufacturing a three-dimensional object by stereolithography using a photocurable composition according to any one of claims 1 to 6.

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