The product can be cured by light.

Abstract

Normally, it is difficult to obtain storage stability and light-curing capability by adding a polythiool compound to a compound containing (met)acryloyl groups. The invention relates to a light-curing composition comprising components (A) to (D): Component (A): compound containing (met)acryloyl groups, Component (B): polythiool compound, Component (C): optically active agent, Component (D): storage stabilizer with pKa from 1.0 to 4.0 (excluding component (A)).

Description

photocurable composition

[0001] The present invention relates to a photocurable composition containing a thiol compound.

[0002] It is known that adding a polythiol compound to a compound having a (meth)acryloyl group improves surface curability. Because of its high reactivity, storage stability tends to decrease. By adding a polymerization inhibitor such as that used in International Publication No. 2017 / 154428 (corresponding to the specification of U.S. Patent Application Publication No. 2019 / 0040175), radical polymerization can be suppressed and storage stability can be improved.

[0003] However, at the same time, there is a disadvantage that the photocurability is reduced, and there is a trade-off between storage stability and curability. Conventionally, it has been difficult to achieve both storage stability and photocurability by adding a polythiol compound to a compound having a (meth)acryloyl group.

[0004] Therefore, 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 has both storage stability and photocurability.

[0005] As a result of extensive research conducted by the present inventors to achieve the above object, they have completed the present invention, which is a photocurable composition.

[0006] The gist of the present invention is explained below. A first embodiment of the present invention is a photocurable composition containing components (A) to (D). Component (A): a compound having a (meth)acryloyl group; component (B): a polythiol compound; component (C): a photoinitiator; and component (D): a storage stabilizer having a pKa of 1.0 to 4.0 (not including component (A)).

[0007] A second embodiment of the present invention is the photocurable composition according to the first embodiment, in which the component (D) is a phosphorus compound.

[0008] In a third embodiment of the present invention, the phosphorus compound is a phosphonic acid compound R １ -P(=O)(OR ２ ) ２ (where R １is an organic group that is not bonded to a hydrogen atom or a phosphorus atom via an oxygen atom, and R ２ and each independently represent a hydrogen atom or an organic group.

[0009] A fourth embodiment of the present invention is the photocurable composition according to the first embodiment, wherein the component (D) is at least one selected from the group consisting of phosphoric acid, oxalic acid, 2-ethylhexyl (2-ethylhexyl)phosphonate, phenylphosphonic acid, vinylphosphonic acid, and methylphosphonic acid.

[0010] A fifth embodiment of the present invention is the photocurable composition according to any one of the first to fourth embodiments, wherein the component (D) is contained in an amount of 0.01 to 10.0 mass % relative to the total mass of the composition.

[0011] A sixth embodiment of the present invention is the photocurable composition according to any one of the first to fifth embodiments, wherein the composition does not contain any storage stabilizer other than the component (D).

[0012] A seventh embodiment of the present invention is the photocurable composition according to any one of the first to sixth embodiments, wherein the (B) component is contained in an amount of 0.1 to 50 parts by mass, and the (C) component is contained in an amount of 0.1 to 10 parts by mass, relative to 100 parts by mass of the (A) component.

[0013] An eighth embodiment of the present invention is the photocurable composition according to any one of the first to seventh embodiments, wherein the component (A) comprises a (meth)acrylate oligomer and a (meth)acrylate monomer.

[0014] A ninth embodiment of the present invention is the photocurable composition according to the eighth embodiment, wherein the (meth)acrylate monomer consists solely of a monofunctional (meth)acrylate and / or a difunctional (meth)acrylate.

[0015] A tenth embodiment of the present invention is the photocurable composition according to the ninth embodiment, wherein the monofunctional (meth)acrylate is a monofunctional (meth)acrylate having a hydroxyl group.

[0016] An eleventh embodiment of the present invention is the photocurable composition according to the ninth or tenth embodiment, wherein the bifunctional (meth)acrylate is dimethyloltricyclodecane diacrylate.

[0017] A twelfth embodiment of the present invention is a photocurable composition according to any one of the first to eleventh embodiments, which is used for nails or artificial nails.

[0018] In a thirteenth embodiment of the present invention, the photocurable composition used for a nail or artificial nail according to the twelfth embodiment is a photocurable composition for a top coat (the photocurable composition according to any of the first to eleventh embodiments is a photocurable composition for a top coat used for a nail or artificial nail).

[0019] A first aspect of the present invention relates to a photocurable composition comprising the following components (A) to (D): component (A): a compound having a (meth)acryloyl group; component (B): a polythiol compound; component (C): a photoinitiator; and component (D): a storage stabilizer having a pKa of 1.0 to 4.0 (excluding component (A)).

[0020] According to the above-mentioned configuration, it is possible to provide a photocurable composition containing a compound having a (meth)acryloyl group and a polythiol compound, which has high storage stability while not reducing curability. That is, according to the above-mentioned configuration, it is possible to provide a photocurable composition that has both storage stability and photocurability.

[0021] In this specification, the photocurable composition is also referred to simply as the "composition" or the "composition according to the present invention."

[0022] Preferred embodiments of the present invention will be described below. Note that the present invention is not limited to the following embodiments and can be modified in various ways within the scope of the claims. The embodiments described in this specification can be combined in any way to form other embodiments.

[0023] Furthermore, throughout this specification, singular expressions should be understood to include the plural concept unless otherwise specified. Therefore, singular articles (e.g., "a," "an," "the," etc. in English) should be understood to include the plural concept unless otherwise specified. Furthermore, terms used in this specification should be understood to be used in the sense commonly used in the art unless otherwise specified. Therefore, unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the present specification (including definitions) will prevail.

[0024] As used herein, the term "(meth)acrylic" encompasses both acrylic and methacrylic. Thus, for example, the term "(meth)acrylic acid" encompasses both acrylic acid and methacrylic acid. Similarly, the term "(meth)acryloyl" encompasses both acryloyl and methacryloyl. Thus, for example, the term "(meth)acryloyl group" encompasses both acryloyl and methacryloyl groups.

[0025] In this specification, "A and / or B" means both A and B, or either A or B.

[0026] The present invention will be described in detail below. The component (A) that can be used in the present invention can be any compound having a (meth)acryloyl group. Specifically, this refers to compounds such as (meth)acrylates and (meth)acrylamides, and the component (A) also includes (meth)acrylate monomers and (meth)acrylate oligomers. The component (A) is preferably composed of a (meth)acrylate oligomer and a (meth)acrylate monomer, and more preferably composed solely of a (meth)acrylate oligomer and a (meth)acrylate monomer. In the above embodiment, the (meth)acrylate monomer is preferably composed of a monofunctional (meth)acrylate and / or a bifunctional (meth)acrylate, more preferably composed solely of a monofunctional (meth)acrylate and / or a bifunctional (meth)acrylate, and particularly preferably composed solely of a monofunctional (meth)acrylate and a bifunctional (meth)acrylate. Hereinafter, acryloyl and methacryloyl will be collectively referred to as (meth)acryloyl, and a compound having a (meth)acryloyl group will also be referred to as (meth)acrylate. Component (A) is preferably liquid in an atmosphere of 25°C, and can be used as long as it has good compatibility with the following components (B) and (C) of the present invention.

[0027] Specific examples of the (meth)acrylate oligomer include (meth)acrylate oligomers having an ester bond in the molecule, (meth)acrylate oligomers having an ether bond in the molecule, (meth)acrylate oligomers having a urethane bond in the molecule, and epoxy-modified (meth)acrylate oligomers, and the main skeletons thereof include, but are not limited to, bisphenol A, novolac phenol, polybutadiene, polyester, and polyether. Furthermore, the component (A) that can be used in the present invention also includes compounds having one or more epoxy groups and one or more (meth)acryloyl groups in one molecule. To improve surface curability, the component (A) preferably contains a (meth)acrylate oligomer having three or more (meth)acryloyl groups in one molecule (the number of functional groups is three or more). When component (A) contains a (meth)acrylate oligomer having three or more (meth)acryloyl groups (three or more functional groups) per molecule, the upper limit of the number of (meth)acryloyl groups (number of functional groups) per molecule of the (meth)acrylate oligomer is preferably 10 or less.

[0028] As a (meth)acrylate oligomer having an ester bond, a synthesis method in which a polyol and a polycarboxylic acid form an ester bond and acrylic acid is added to unreacted hydroxyl groups is known, but the synthesis method is not limited to this. Specific examples include Aronix M-6100, M-6200, M-6250, M-6500, M-7100, M-7300K, M-8030, M-8060, M-8100, M-8530, M-8560, and M-9050 manufactured by Toagosei Co., Ltd., and UV-3500BA, UV-3520TL, UV-3200B, and UV-3000B manufactured by The Nippon Synthetic Chemical Industry Co., Ltd., but are not limited thereto.

[0029] For (meth)acrylate oligomers having an ether bond, a synthesis method in which acrylic acid is added to the hydroxyl groups of a polyether polyol or to the hydroxyl groups of a polyether polyol having an aromatic group such as bisphenol is known, but the synthesis method is not limited to this. Specific examples include UV-6640B, UV-6100B, and UV-3700B manufactured by Nippon Synthetic Chemical Industry Co., Ltd., Light (meth)acrylate 3EG-A, 4EG-A, 9EG-A, 14EG-A, PTMGA-250, BP-4EA, BP-4PA, and BP-10EA manufactured by Kyoeisha Chemical Co., Ltd., EBECRYL3700 manufactured by Daicel-Cytec Co., Ltd., and KY-11 manufactured by Negami Chemical Industrial Co., Ltd., but are not limited thereto.

[0030] Known examples of (meth)acrylate oligomers having a urethane bond include synthesis in which a urethane bond is formed using a polyol and a polyisocyanate, and then a compound having a hydroxyl group and a (meth)acryloyl group in the molecule or (meth)acryloyl acid is added to the remaining isocyanate group. From the viewpoint of improving durability, it is preferable to add a (meth)acrylate oligomer having a urethane bond. Specific examples include AH-600, AT-600, UA-306H, and UF-8001G manufactured by Kyoeisha Chemical Co., Ltd., and UN-3320HA and UN-904 manufactured by Negami Chemical Industrial Co., Ltd., but are not limited thereto.

[0031] Epoxy-modified (meth)acrylate oligomers can be synthesized by ring-opening polymerization of (meth)acrylic acid or the like with the glycidyl group of a polyfunctional glycidyl ether compound, but are not limited thereto. The main chain of the polyfunctional glycidyl ether can have a variety of skeletons, such as bisphenol A, bisphenol F, and novolac phenol. Specific examples of the epoxy-modified acrylic oligomer include, but are not limited to, Epoxy Ester 3000A and 3002A manufactured by Kyoeisha Chemical Co., Ltd., and EBECRYL 3700 manufactured by Daicel-Allnex Corporation.

[0032] The weight average molecular weight (or molecular weight) of the (meth)acrylate oligomer is preferably 1,000 to 50,000. If it is 1,000 or more, the cured product will exhibit toughness, and if it is 50,000 or less, the viscosity of the composition can be kept low. More preferably, the weight average molecular weight (or molecular weight) of the (meth)acrylate oligomer is more than 1,000 and 10,000 or less, and particularly preferably 1,500 to 5,000. Here, the weight average molecular weight refers to the weight average molecular weight in terms of polystyrene measured by gel permeation chromatography.

[0033] The (meth)acrylate monomer may include monofunctional, difunctional, or trifunctional (meth)acrylate monomers and (meth)acrylamide monomers. A combination of a plurality of other monomers may also be used.

[0034] Specific examples of monofunctional (meth)acrylate monomers include lauryl (meth)acrylate, stearyl (meth)acrylate, ethyl carbitol (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, caprolactone-modified tetrahydrofurfuryl (meth)acrylate, cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, isobornyl (meth)acrylate, benzyl (meth)acrylate, phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxytetraethylene glycol (meth)acrylate, nonylphenoxyethyl (meth)acrylate, nonylphenoxytetraethylene glycol (meth)acrylate, methoxydiethylene glycol (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, Examples of suitable acrylates include, but are not limited to, butoxyethyl (meth)acrylate, butoxytriethylene glycol (meth)acrylate, 2-ethylhexyl polyethylene glycol (meth)acrylate, 4-hydroxybutyl (meth)acrylate, nonylphenyl polypropylene glycol (meth)acrylate, methoxydipropylene glycol (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, glycerol (meth)acrylate, polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, epichlorohydrin-modified butyl (meth)acrylate, epichlorohydrin-modified phenoxy (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, and N,N-diethylaminoethyl (meth)acrylate. Preferably, component (A) contains a monofunctional monomer having a hydroxyl group. That is, in a preferred embodiment of the present invention, the monofunctional (meth)acrylate is a monofunctional (meth)acrylate having a hydroxyl group, and specific examples thereof include, but are not limited to, 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, and 2-hydroxypropyl (meth)acrylate.Preferably, the monofunctional (meth)acrylate is at least one selected from the group consisting of 2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate, more preferably 2-hydroxypropyl acrylate and / or 2-hydroxypropyl methacrylate.

[0035] The monofunctional (meth)acrylate monomer also includes a (meth)acrylate monomer having an acidic group, particularly a carboxylic acid or phosphoric acid having a (meth)acryloyl group in the molecule. Examples of carboxylic acids having a (meth)acryloyl group in the molecule include, but are not limited to, (meth)acryloyl acid, 3-(meth)acryloyloxypropyl succinic acid, 4-(meth)acryloyloxybutyl succinic acid, 2-(meth)acryloyloxyethyl maleic acid, 3-(meth)acryloyloxypropyl maleic acid, 4-(meth)acryloyloxybutyl maleic acid, 2-(meth)acryloyloxyethyl hexahydrophthalic acid, 3-(meth)acryloyloxypropyl hexahydrophthalic acid, 4-(meth)acryloyloxybutyl hexahydrophthalic acid, 2-(meth)acryloyloxyethyl phthalic acid, 3-(meth)acryloyloxypropyl phthalic acid, and 4-(meth)acryloyloxybutyl phthalic acid. Examples of phosphoric acids having a (meth)acryloyl group in the molecule include, but are not limited to, 2-ethylhexyl acid phosphate, 2-hydroxyethyl methacrylate acid phosphate, dibutyl phosphate, etc. In order to improve durability, it is preferable to include a (meth)acrylate monomer having an acidic group.

[0036] Specific examples of bifunctional (meth)acrylate monomers include 1,3-butylene glycol di(meth)acrylate, 1,4-butylene glycol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexane glycol di(meth)acrylate, ethylene glycol diacrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, dimethylol tricyclodecane di(meth)acrylate, and ethylene oxide-modified ethylene glycol diacrylate. Examples of the difunctional (meth)acrylate include, but are not limited to, neopentyl glycol di(meth)acrylate, propylene oxide-modified neopentyl glycol di(meth)acrylate, bisphenol A di(meth)acrylate, ethylene oxide-modified bisphenol A di(meth)acrylate, epichlorohydrin-modified bisphenol A di(meth)acrylate, ethylene oxide-modified bisphenol S di(meth)acrylate, neopentyl glycol-modified trimethylolpropane di(meth)acrylate, dicyclopentenyl di(meth)acrylate, ethylene oxide-modified dicyclopentenyl di(meth)acrylate, and diacryloyl isocyanurate. Considering the improvement of curability, it is preferable to use dimethyloltricyclodecane di(meth)acrylate, and more preferably dimethyloltricyclodecane diacrylate. That is, in a preferred embodiment of the present invention, the bifunctional (meth)acrylate monomer is dimethyloltricyclodecane di(meth)acrylate. In a more preferred embodiment of the invention, the difunctional (meth)acrylate monomer is dimethyloltricyclodecane diacrylate.

[0037] Specific examples of trifunctional (meth)acrylate monomers include trimethylolpropane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, EO-modified trimethylolpropane tri(meth)acrylate, PO-modified trimethylolpropane tri(meth)acrylate, ECH-modified trimethylolpropane tri(meth)acrylate, ECH-modified glycerol tri(meth)acrylate, and tris(acryloyloxyethyl)isocyanurate, but are not limited to these.

[0038] Specific examples of (meth)acrylamide monomers include, but are not limited to, dimethyl(meth)acrylamide, (meth)acryloylmorpholine, and diethyl(meth)acrylamide. Although the exact cause is unknown, from the viewpoint of improving durability, it is preferable that the monomer contains a (meth)acrylamide monomer. In the present invention, specific examples of (meth)acrylamide monomers known include, but are not limited to, DMAA, ACMO, and DEAA manufactured by KJ Chemical Co., Ltd.

[0039] Component (A) preferably contains both a (meth)acrylate oligomer and a (meth)acrylate monomer. When component (A) is composed of a (meth)acrylate oligomer and a (meth)acrylate monomer, the ratio of oligomer to monomer (mass ratio of (meth)acrylate oligomer:(meth)acrylate monomer) is preferably 50:50 to 95:5, and more preferably 55:45 to 65:35 or less. The inclusion of a (meth)acrylate oligomer improves durability. Note that when the (meth)acrylate oligomer is a mixture of two or more types, the above composition refers to the composition of the total amount of (meth)acrylate oligomer. Similarly, when the (meth)acrylate monomer is a mixture of two or more types, the above composition refers to the composition of the total amount of (meth)acrylate monomer.

[0040] Furthermore, the (meth)acrylate monomer is preferably a mixture of monofunctional and difunctional or higher functional monomers, more preferably a mixture of monofunctional and difunctional monomers (i.e., a mixture of monofunctional (meth)acrylate and bifunctional (meth)acrylate), and particularly preferably a mixture consisting solely of monofunctional (meth)acrylate and bifunctional (meth)acrylate. In this case, the mixing ratio of the monofunctional (meth)acrylate to the bifunctional (meth)acrylate (mass ratio of monofunctional (meth)acrylate:bifunctional (meth)acrylate) is preferably 50:50 to 90:10, more preferably 70:30 to 80:20. In addition, when two or more types of monofunctional (meth)acrylates are mixed, the above composition refers to the composition of the total amount of monofunctional (meth)acrylates. Similarly, when two or more types of bifunctional (meth)acrylates are mixed, the above composition refers to the composition of the total amount of bifunctional (meth)acrylates. Furthermore, the above mixing ratio is particularly preferably adopted when component (A) consists only of a (meth)acrylate oligomer and a (meth)acrylate monomer, and the (meth)acrylate monomer consists only of a monofunctional (meth)acrylate and a difunctional (meth)acrylate.

[0041] The component (B) that can be used in the present invention is a polythiol compound. The component (B) is not particularly limited as long as it has two or more thiol groups, and may be used alone or in combination of two or more. Specific examples of the component (B) include, but are not limited to, aliphatic polythiol compounds, aromatic polythiol compounds, and polythiol compounds having sulfide bonds.

[0042] Examples of aliphatic polythiol compounds having two thiol groups include 1,2-ethanedithiol, 1,2-propanedithiol, 1,3-propanedithiol, 1,4-butanedithiol, 1,6-hexanedithiol, 1,7-heptanedithiol, 1,8-octanedithiol, 1,9-nonanedithiol, 1,10-decanedithiol, 1,12-dodecanedithiol, 2,2-dimethyl-1,3-propanedithiol, 3-methyl-1,5-pentanedithiol, 2-methyl-1,8-octanedithiol, and 1 ,4-cyclohexanedithiol, 1,4-bis(mercaptomethyl)cyclohexane, 1,1-cyclohexanedithiol, 1,2-cyclohexanedithiol, bicyclo[2,2,1]hepta-exo-cis-2,3-dithiol, 1,1-bis(mercaptomethyl)cyclohexane, bis(2-mercaptoethyl)ether, ethylene glycol bis(2-mercaptoacetate), and ethylene glycol bis(3-mercaptopropionate).

[0043] Aliphatic polythiol compounds having three thiol groups include, but are not limited to, 1,1,1-tris(mercaptomethyl)ethane, 2-ethyl-2-mercaptomethyl-1,3-propanedithiol, 1,2,3-propanetrithiol, trimethylolpropane tris(2-mercaptoacetate), trimethylolpropane tris(3-mercaptopropionate), and tris[(mercaptopropionyloxy)-ethyl]isocyanurate.

[0044] Examples of aliphatic polythiol compounds having four or more thiol groups include, but are not limited to, pentaerythritol tetrakis(2-mercaptoacetate), pentaerythritol tetrakis(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate), and dipentaerythritol hexakis(3-mercaptopropionate).

[0045] Examples of aromatic polythiol compounds include 1,2-dimercaptobenzene, 1,3-dimercaptobenzene, 1,4-dimercaptobenzene, 1,2-bis(mercaptomethyl)benzene, 1,3-bis(mercaptomethyl)benzene, 1,4-bis(mercaptomethyl)benzene, 1,2-bis(2-mercaptoethyl)benzene, 1,3-bis(2-mercaptoethyl)benzene, 1,4-bis(2-mercaptoethyl)benzene, 1,2-bis(2-mercaptoethyleneoxy)benzene, and 1,3-bis(2-mercaptoethyleneoxy)benzene. 1,4-bis(2-mercaptoethyleneoxy)benzene, 1,2,3-trimercaptobenzene, 1,2,4-trimercaptobenzene, 1,3,5-trimercaptobenzene, 1,2,3-tris(mercaptomethyl)benzene, 1,2,4-tris(mercaptomethyl)benzene, 1,3,5-tris(mercaptomethyl)benzene, 1,2,3-tris(2-mercaptoethyl)benzene, 1,2,4-tris(2-mercaptoethyl)benzene, 1,3,5-tris(2-mercaptoethyl)benzene, 1,2,3-tris(2-mercapto 1,2,4-Tris(2-mercaptoethyleneoxy)benzene, 1,3,5-Tris(2-mercaptoethyleneoxy)benzene, 1,2,3,4-tetramercaptobenzene, 1,2,3,5-tetramercaptobenzene, 1,2,4,5-tetramercaptobenzene, 1,2,3,4-tetrakis(mercaptomethyl)benzene, 1,2,3,5-tetrakis(mercaptomethyl)benzene, 1,2,4,5-tetrakis(mercaptomethyl)benzene, 1,2,3,4-tetrakis(2-mercaptoethyl)benzene benzene, 1,2,3,5-tetrakis(2-mercaptoethyl)benzene, 1,2,4,5-tetrakis(2-mercaptoethyl)benzene, 1,2,3,4-tetrakis(2-mercaptoethyleneoxy)benzene, 1,2,3,5-tetrakis(2-mercaptoethyleneoxy)benzene, 1,2,4,5-tetrakis(2-mercaptoethyleneoxy)benzene, 2,2'-mercaptobiphenyl, 4,4'-thiobis-benzenethiol, 4,4'-dimercaptobiphenyl, 4,4'-dimercaptobibenzyl, 2,5-toluenedithiol, 3,4-toluenedithiol, 1,4-naphthalenedithiol, 1,5-naphthalenedithiol, 2,6-naphthalenedithiol, 2,7-naphthalenedithiol, 2,4-dimethylbenzene-1,3-dithiol, 4,5-dimethylbenzene-1,3-dithiol, 9,10-anthracenedimethanethiol, 1,3-bis(2-mercaptoethylthio)benzene, 1,4-bis(2-mercaptoethylthio)benzene, 1,2-bis(2-mercaptoethylthiomethyl)benzene, 1,3-bis(2-mercaptoethylthiomethyl)benzene Examples of the mercaptoethylthio include, but are not limited to, benzene, 1,4-bis(2-mercaptoethylthiomethyl)benzene, 1,2,3-tris(2-mercaptoethylthio)benzene, 1,2,4-tris(2-mercaptoethylthio)benzene, 1,3,5-tris(2-mercaptoethylthio)benzene, 1,2,3,4-tetrakis(2-mercaptoethylthio)benzene, 1,2,3,5-tetrakis(2-mercaptoethylthio)benzene, and 1,2,4,5-tetrakis(2-mercaptoethylthio)benzene.

[0046] Examples of polythiol compounds having a sulfide bond include, but are not limited to, bis(2-mercaptoethyl)sulfide, bis(2-mercaptoethylthio)methane, 1,2-bis(2-mercaptoethylthio)ethane, 1,3-bis(2-mercaptoethylthio)propane, 1,2,3-tris(2-mercaptoethylthio)propane, tetrakis(2-mercaptoethylthiomethyl)methane, 1,2-bis(2-mercaptoethylthio)propanethiol, 2,5-dimercapto-1,4-dithiane, bis(2-mercaptoethyl)disulfide, 3,4-thiophenedithiol, 1,2-bis(2-mercaptoethyl)thio-3-mercaptopropane, and bis-(2-mercaptoethylthio-3-mercaptopropane)sulfide.

[0047] Specific examples of the component (B) having a secondary thiol group include, but are not limited to, pentaerythritol tetrakis(3-mercaptobutyrate), 1,4-bis(3-mercaptobutyryloxy)butane, 1,3,5-tris(3-mercaptobutyryloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, trimethylolpropane tris(3-mercaptobutyrate), trimethylolethane tris(3-mercaptobutyrate), trimethylolpropane tris(3-mercaptobutyrate), and trimethylolethane tris(3-mercaptobutyrate). Commercial examples include, but are not limited to, PEMP manufactured by SC Organic Chemical Co., Ltd. and PE1, BD1, and NR1 of the Karenz MT (registered trademark) series manufactured by Showa Denko K.K.

[0048] The amount of component (B) is preferably 0.1 to 50 parts by mass per 100 parts by mass of component (A). The amount of component (B) is particularly preferably 1 to 30 parts by mass, and most preferably 10 to 20 parts by mass per 100 parts by mass of component (A). When component (B) is present in an amount of 0.1 part by mass or more, surface curability is improved, and when component (B) is present in an amount of 50 parts by mass or less, storage stability is improved. When component (B) is a mixture of two or more types, the above composition refers to the composition of the total amount of component (B).

[0049] The component (C) that can be used in the present invention is a photoinitiator. There are no limitations on the component (C) as long as it is a radical photoinitiator that generates radical species when exposed to energy rays such as visible light, ultraviolet light, X-rays, and electron beams.

[0050] Specific examples of the component (C) include acetophenones such as diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyl dimethyl ketal, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-2-morpholino(4-thiomethylphenyl)propan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone, and 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone oligomer; benzoins such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether; benzophenone, methyl o-benzoylbenzoate, and 4-phenylbenzyl ether; Benzophenones such as benzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, 3,3',4,4'-tetra(t-butylperoxycarbonyl)benzophenone, 2,4,6-trimethylbenzophenone, 4-benzoyl-N,N-dimethyl-N-[2-(1-oxo-2-propenyloxy)ethyl]benzenemethanaminium bromide, and (4-benzoylbenzyl)trimethylammonium chloride; and thioxanthones such as 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone, and 2-(3-dimethylamino-2-hydroxy)-3,4-dimethyl-9H-thioxanthone-9-one mesochloride, but are not limited thereto. Furthermore, multiple components (C) can also be used in combination.

[0051] The amount of component (C) added is 0.1 to 20 parts by mass, more preferably 0.1 to 10 parts by mass, and particularly preferably 2 to 4 parts by mass, per 100 parts by mass of component (A). When the amount of component (C) is more than 0.1 part by mass, photocurability can be maintained. On the other hand, when the amount of component (C) is less than 20 parts by mass, storage stability can be maintained without an increase in viscosity during storage. Note that when component (C) is a mixture of two or more types, the above composition refers to the composition of the total amount of component (C).

[0052] In a preferred embodiment of the present invention, the component (B) is contained in an amount of 0.1 to 50 parts by mass, and the component (C) is contained in an amount of 0.1 to 20 parts by mass, per 100 parts by mass of the component (A). In a more preferred embodiment of the present invention, the component (B) is contained in an amount of 0.1 to 50 parts by mass, and the component (C) is contained in an amount of 0.1 to 10 parts by mass, per 100 parts by mass of the component (A). In a further preferred embodiment of the present invention, the component (B) is contained in an amount of 1 to 30 parts by mass, and the component (C) is contained in an amount of 0.1 to 10 parts by mass, per 100 parts by mass of the component (A). In a particularly preferred embodiment of the present invention, the component (B) is contained in an amount of 10 to 20 parts by mass, and the component (C) is contained in an amount of 2 to 4 parts by mass, per 100 parts by mass of the component (A).

[0053] Furthermore, instead of or in addition to the photoinitiator, it is preferable to include a visible light photoinitiator as component (C). It is more preferable that component (C) includes the photoinitiator and a visible light photoinitiator. It is even more preferable that component (C) consists solely of the photoinitiator and a visible light photoinitiator. In the above embodiment, the visible light photoinitiator is preferably included in the total amount of component (C) from 0 to 70% by mass, more preferably from 40 to 60% by mass, and particularly preferably from 45 to 55% by mass. Alternatively, the visible light photoinitiator is preferably included in an amount of 0.1 to 20 parts by mass, more preferably from 0.1 to 10 parts by mass, and particularly preferably from 2 to 4 parts by mass, per 100 parts by mass of component (A). Within these ranges, the cured product is less likely to yellow. Note that when the visible light photoinitiator is a mixture of two or more types, the above composition refers to the composition of the total amount of visible light photoinitiators. Here, the visible light photoinitiator is a photoinitiator that has the strongest light absorption in the visible light region, and refers to an acylphosphine oxide photopolymerization initiator that mainly contains a phosphorus atom. Specific examples include, but are not limited to, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide.

[0054] The component (D) that can be used in the present invention is a storage stabilizer with a pKa (acid dissociation constant) of 1.0 to 4.0, and does not include components (A) and (C). More specifically, it is an organic or inorganic acid with a pKa of 1.0 to 4.0. Although the exact cause is unknown, adding it to the composition of the present invention improves both storage stability, such as viscosity, and surface curability. pKa is an index that quantitatively represents the strength of an acid (ease of dissociation of hydrogen ions) and is expressed as the negative common logarithm of the equilibrium constant (Ka) of the dissociation reaction in which a proton is released from the acid. The lower the pKa, the stronger the acid. pKa is known to be measured by neutralization titration, absorptiometry, capillary electrophoresis, etc., with neutralization titration being the most accurate. From the perspective of further improving storage stability, the pKa of the storage stabilizer used as component (D) is preferably 1.0 or more but less than 2.3, more preferably 1.50 to 2.20.

[0055] Particularly preferred as component (D) are phosphorus compounds as storage stabilizers. Here, phosphonic acid and phosphoric acid are collectively referred to as phosphorus compounds. The most preferred are phosphonic acid compounds. The phosphonic acid compounds are those having the formula R １ -P(=O)(OR ２ ) ２ where R １ is an organic group that is not bonded to a hydrogen atom or a phosphorus atom via an oxygen atom, and R ２ are each independently a hydrogen atom or an organic group. ２ may be the same or different. １ is R ２ That is, in a preferred embodiment of the present invention, the component (D) is a phosphorus compound, and the phosphorus compound is represented by the formula: R １ -P(=O)(OR ２ ) ２ (where R １ is an organic group that is not bonded to a hydrogen atom or a phosphorus atom via an oxygen atom, and R ２are each independently a hydrogen atom or an organic group). In the above formula, examples of the organic group include aromatic groups such as a phenyl group and a naphthyl group, and hydrocarbon groups, but are not limited to these. Examples of the hydrocarbon group include an alkyl group, an alkenyl group, and an alkynyl group. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a tert-pentyl group, a neopentyl group, a 1,2-dimethylpropyl group, an n-hexyl group, an isohexyl group, a 1,3-dimethylbutyl group, a 1-isopropylpropyl group, a 1,2-dimethylbutyl group, an n-heptyl group, a 1,4-dimethylpentyl group, a 3-ethylpentyl group, and a 2-methyl-1-isopropylpropyl group. Examples of the alkenyl group include vinyl, 1-ethyl-3-methylbutyl, n-octyl, 2-ethylhexyl, 3-methyl-1-isopropylbutyl, 2-methyl-1-isopropyl, 1-tert-butyl-2-methylpropyl, n-nonyl, 3,5,5-trimethylhexyl, n-decyl, isodecyl, n-undecyl, 1-methyldecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, and n-octadecyl groups. Examples of the alkenyl group include vinyl, allyl, 1-propenyl, 2-butenyl, 1,3-butadienyl, 2-pentenyl, and isopropenyl groups. Examples of the alkynyl group include ethynyl and propargyl groups. The hydrocarbon group may have any substituent such as a halogen atom, an amino group, a cyano group, a nitro group, or a hydroxy group. The most preferred component (D) is phenylphosphonic acid. The component (D) may be used alone or in combination, but it is preferred that the composition does not contain any storage stabilizer other than the component (D). Usually, phosphoric acid is P(=O)(OH) ３ and phosphonic acid H-P(=O)(OH) ２ It is different from.

[0056] Specific examples of component (D) include phosphoric acid, oxalic acid, and phosphonic acid compounds. In particular, phosphonic acid compounds include 2-ethylhexyl (2-ethylhexyl)phosphonate, phenylphosphonic acid, vinylphosphonic acid, and methylphosphonic acid, but are not limited to these. A particularly preferred component (D) is a phosphonic acid compound. Component (D) may be used alone or in combination with multiple types. Furthermore, in order to avoid reducing storage stability in terms of viscosity, etc., it is preferable not to use an organic acid or inorganic acid with a pKa greater than 4.0 in combination with component (D). That is, in a preferred embodiment of the present invention, the composition does not contain an organic acid or inorganic acid with a pKa greater than 4.0.

[0057] That is, in a preferred embodiment of the present invention, component (D) is at least one selected from the group consisting of phosphoric acid, oxalic acid, 2-ethylhexyl (2-ethylhexyl)phosphonate, phenylphosphonic acid, vinylphosphonic acid, and methylphosphonic acid. In a more preferred embodiment of the present invention, component (D) is at least one selected from the group consisting of 2-ethylhexyl (2-ethylhexyl)phosphonate, phenylphosphonic acid, vinylphosphonic acid, and methylphosphonic acid. In a further preferred embodiment of the present invention, component (D) is at least one selected from the group consisting of phenylphosphonic acid, vinylphosphonic acid, and methylphosphonic acid. In a particularly preferred embodiment of the present invention, component (D) is phenylphosphonic acid.

[0058] The amount of component (D) added per 100 parts by mass of component (A) is preferably 0.01 to 5.0 parts by mass, more preferably 0.01 to 2.0 parts by mass, and most preferably 0.05 to 1.5 parts by mass. When the amount of component (D) is 0.01 part by mass or more, viscosity change is suppressed, and when the amount is 5.0 parts by mass or less, surface curability is maintained. Furthermore, particularly from the viewpoint of further improving storage stability (further suppressing viscosity change), the amount of component (D) added per 100 parts by mass of component (A) is preferably less than 1.5 parts by mass, more preferably 0.05 to 1.0 part by mass.

[0059] The content of component (D) is preferably 0.01 to 10.0% by mass, more preferably 0.1 to 5.0% by mass, and particularly preferably 0.04 to 1.5% by mass, of the entire composition. From the viewpoint of further improving storage stability (further suppressing viscosity change), the content of component (D) is preferably less than 1.00% by mass, and more preferably 0.04 to 0.82% by mass, of the entire composition.

[0060] The present invention may contain additives such as coupling agents, inorganic or organic fillers, colorants such as pigments and dyes, antioxidants, polymerization inhibitors, antifoaming agents, leveling agents, rheology control agents, slip agents, etc. in appropriate amounts within the range that does not impair the properties of the present invention. The addition of these additives can provide a composition or a cured product thereof that is excellent in resin strength, adhesive strength, workability, storage stability, etc.

[0061] In the present invention, a coupling agent can be added as long as it does not impair the properties of the present invention. Examples of coupling agents include, but are not limited to, silane coupling agents having both an epoxy group, a vinyl group, an acryloyl group, or a methacryloyl group and a hydrolyzable silane group, polyorganosiloxanes having a phenyl group and a hydrolyzable silyl group, and / or polyorganosiloxanes having an epoxy group and a hydrolyzable silyl group. Specific examples of silane coupling agents include, but are not limited to, allyltrimethoxysilane, vinyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, and 3-chloropropyltrimethoxysilane.

[0062] In the present invention, fillers such as inorganic fillers and organic fillers can be appropriately added as long as the properties of the present invention are not impaired. Adding a filler can adjust not only the viscosity and thixotropy but also the curing property and toughness. Examples of inorganic fillers include, but are not limited to, alumina, silica, and amorphous silica. Examples of organic fillers include, but are not limited to, styrene fillers, rubber fillers, and core-shell acrylic fillers. Specific examples of silica products include FUSELEX E-1 manufactured by Tatsumori Co., Ltd. and AO-802 manufactured by Adma Fine Co., Ltd. Examples of amorphous silica products include, but are not limited to, the Aerosil series manufactured by Nippon Aerosil Japan Co., Ltd., such as 200 (untreated), R972 (dimethyldichlorosilane-treated), R976 (dimethyldichlorosilane-treated), RY200 (dimethylsilicone-treated), RX200 (hexamethyldisilazane-treated), and R800 (octylsilane-treated).

[0063] In the present invention, a slip agent can be added within a range that does not impair the characteristics of the present invention. When a slip agent is included, the surface becomes smooth due to a leveling action, and abrasion resistance is improved. The slip agent is not particularly limited, but for example, a silicone surfactant such as polyester-modified silicone or polyether-modified silicone can be used, and it is preferable to use polyether-modified polydimethylsiloxane or polyester-modified polydimethylsiloxane.

[0064] When the composition contains a slip agent, the content of the slip agent is preferably 0.01 to 5.0 parts by mass, and more preferably 0.1 to 1.0 part by mass, per 100 parts by mass of component (A).

[0065] Before applying the composition of the present invention, it is preferable to sand the surface of a human nail with a file or the like, and then remove dust, oil, moisture, etc. with a nail-specific solvent containing ethanol as the main ingredient. When applying the composition of the present invention, a coating film having a thickness of 100 to 300 μm before curing can be formed using a brush or paintbrush. A primer may be used before application. The method for curing the composition of the present invention is preferably to cure the composition by irradiating it with active energy rays. Commercially available UV lamps or LED lamps can be used as irradiators for curing. The irradiation time is 15 to 120 seconds, and, considering the effects on the fingers, is preferably 20 to 70 seconds. The integrated light dose is preferably 1 to 30 kJ / m. ２ is.

[0066] In compounds having a (meth)acryloyl group, polymerization is inhibited in areas exposed to oxygen due to oxygen inhibition. The present invention is less susceptible to oxygen inhibition and is rapidly curable upon light irradiation, making it suitable for nails or artificial nails, particularly top coats for nails or artificial nails. That is, in one aspect of the present invention, the photocurable composition of the present invention is used for nails or artificial nails. In one aspect of the present invention, the photocurable composition of the present invention is used for nails or artificial nails and is used as a top coat (the photocurable composition of the present invention is a photocurable composition for a top coat used for nails or artificial nails).

[0067] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0068] [Examples 1 to 11, Comparative Examples 1 to 14, Reference Examples 1 to 3] The following components were prepared to prepare photocurable compositions. (Hereinafter, the photocurable compositions may also be simply referred to as compositions.)) Component (A): Compound having a (meth)acryloyl group - Polyether-based urethane acrylate oligomer having a weight average molecular weight of 5000 and a functionality of 3 (KY-11 manufactured by Negami Chemical Industrial Co., Ltd.) (liquid at 25°C) - Urethane acrylate oligomer having a weight average molecular weight of 1500 and a functionality of 6 (UN-3320HA manufactured by Negami Chemical Industrial Co., Ltd.) (liquid at 25°C) - Urethane acrylate oligomer having a weight average molecular weight of 4900 and a functionality of 10 (UN-904 manufactured by Negami Chemical Industrial Co., Ltd.) (liquid at 25°C) - Polycarbonate-based urethane acrylate oligomer having a weight average molecular weight of 4500 and a functionality of 2 (UF-8001G manufactured by Kyoeisha Chemical Co., Ltd.) (liquid at 25°C) - Dimethyloltricyclodecane diacrylate (light acrylate DCP-A Component (B): Polythiol compound; Trimethylolpropane tris(3-mercaptopropionate) (TMMP-20P, manufactured by SC Organic Chemical Co., Ltd.); Component (C): Photoinitiator; 1-hydroxycyclohexyl phenyl ketone (invisible light photoinitiator) (IRGACURE184, manufactured by BASF); 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (visible light photoinitiator) (LUCIRIN TPO, manufactured by BASF); Component (D): Phosphorus compound as storage stabilizer; Phenylphosphonic acid (reagent); Vinylphosphonic acid (reagent); Methylphosphonic acid (reagent); Phosphoric acid (reagent); Oxalic acid (reagent). Component (D'): Storage stabilizers other than component (D): Acetic acid (reagent), acrylic acid (reagent), benzoic acid (reagent), dibutylhydroxytoluene (BHT) (reagent) (antioxidant), 4-methoxyphenol (MEHQ) (reagent) (polymerization inhibitor), hindered phenol antioxidant with a molecular weight of 1,178 (ADK STAB AO-60, manufactured by ADEKA Corporation), dilauryl thiodipropionate (DLTP "Yoshitomi", manufactured by API Corporation) (antioxidant), and others: Polyether-modified silicone (LS-480, manufactured by Kusumoto Chemicals Co., Ltd.).

[0069] Examples 1 to 5 and Comparative Examples 1 to 3 were prepared. The compositions were prepared by weighing component (A), component (B), component (D) (or component (D')), and other components into a stirring vessel and stirring for 30 minutes. The mixture was then stirred for 30 minutes while being degassed under vacuum. Finally, component (C) was weighed and added to the stirring vessel, followed by stirring for 30 minutes. Detailed amounts prepared are shown in Table 1, and all values ​​are expressed in parts by mass.

[0070]

[0071] Viscosity measurement, surface curability confirmation, and surface condition confirmation of the cured product were carried out for Examples 1 to 5 and Comparative Examples 1 to 3 according to the following methods. The results are summarized in Table 2.

[0072] [Viscosity Measurement] 0.5 ml of the composition was collected and dispensed into a measuring cup. Viscosity measurements were performed using an EHD viscometer (manufactured by Toki Sangyo Co., Ltd.) under the following conditions. The results were recorded as "viscosity (Pa s)." This was taken as the initial viscosity. The composition was then filled into a plastic container and left in a hot air drying oven at 60°C for two days, and the viscosity was measured. If the composition was gelled when the container was opened, it was recorded as "gelled" and viscosity measurement was not performed. If the components were not dissolved, it was recorded as "insoluble" and viscosity measurement was not performed. Considering handling during application and flowability, the viscosity (initial) is preferably 10 Pa s or less, more preferably 5 Pa s or less. The rate of change is preferably 20% or less, more preferably 5.0% or less, and particularly preferably 3.0% or less. Measurement conditions: Cone rotor: 3°×R14 Rotation speed: 100 rpm Measurement time: 3 minutes Measurement temperature: 25° C. (temperature controlled by a thermostatic bath).

[0073] [Confirmation of Surface Curability] The composition was applied with a brush to a thickness of approximately 300 μm on an acrylic plate measuring 2.0 mm thick x 25 mm wide x 100 mm long. The composition was cured by irradiating it with a nail UV lamp (rated voltage: 100-110 V, 50-60 Hz, power consumption: 36 W, wavelength: 350-400 nm) for 30 seconds. The surface condition of the cured product was then visually inspected by touching the surface with a polytetrafluoroethylene rod according to the following evaluation criteria, and this was designated as "surface curability." Evaluation criteria: ◯: No tack of the components occurred on the surface; ×: Tack of the components occurred on the surface.

[0074] [Confirmation of surface condition of cured product] Before checking the surface curability, the surface was visually confirmed by reflecting it on an LED stand according to the following evaluation criteria, and the "surface of the cured product" was determined. Evaluation criteria: ◯: The surface is glossy; ×: The surface is not glossy.

[0075]

[0076] When Examples 1 to 5 containing storage stabilizers with pKa of 1.0 to 4.0 are compared with Comparative Examples 1 to 3 having a pKa greater than 4.0, it is clear that there is no difference in the effect of surface curing, but there is a large difference in storage stability.

[0077] Examples 6 to 11 and Comparative Examples 4 to 14 were prepared. The compositions were prepared by weighing component (A), component (B), component (D) (or component (D')), and other components into a stirring vessel and stirring for 30 minutes. The mixture was then stirred for 30 minutes while being degassed under vacuum. Finally, component (C) was weighed and added to the stirring vessel, followed by stirring for 30 minutes. Detailed amounts prepared are shown in Table 3, and all values ​​are expressed in parts by mass.

[0078]

[0079]

[0080] Viscosity measurements and surface curability confirmation were carried out for Examples 1, 6 to 11 and Comparative Examples 4 to 14 according to the following methods. The results are summarized in Table 4.

[0081] [Viscosity Measurement] 0.5 ml of the composition was sampled and dispensed into a measuring cup. Viscosity measurements were performed using an EHD viscometer (manufactured by Toki Sangyo Co., Ltd.) under the following conditions. The results were recorded as "viscosity (Pa s)." This was taken as the initial viscosity. The composition was then filled into a plastic container and left in a hot air drying oven at 40°C for 21 days, and the viscosity was measured. If the composition was gelled when the container was opened, it was recorded as "gelled" and viscosity measurement was not performed. If the components were not dissolved, it was recorded as "insoluble" and viscosity measurement was not performed. Considering handling during treatment and flowability, the viscosity (initial) is preferably 10 Pa s or less, more preferably 5 Pa s or less. The rate of change is preferably 20% or less, more preferably less than 10.0%. Measurement Conditions: Cone rotor: 3° x R14; Rotation speed: 100 rpm; Measurement time: 3 minutes; Measurement temperature: 25°C (temperature controlled using a thermostatic bath).

[0082] [Confirmation of surface curability] The composition was applied with a brush to a thickness of approximately 300 μm on an acrylic plate measuring 2.0 mm thick x 25 mm wide x 100 mm long. The composition was cured by irradiating it with a nail UV lamp (rated voltage: 100-110 V 50-60 Hz, power consumption: 36 W, wavelength: 350-400 nm) for 30 seconds. The surface condition of the cured product was then visually inspected by touching the surface with a polytetrafluoroethylene rod according to the following evaluation criteria, and this was designated as "surface curability". Evaluation criteria: ◯: No tack of the components occurs on the surface ×: Tack of the components occurs on the surface

[0083]

[0084] In Examples 1 and 6 to 11, phenylphosphonic acid was added as component (D), and the viscosity change rate after 21 days at 40°C was low, indicating that the surface curability was rated "Good." On the other hand, in Comparative Examples 4 to 14, components used as polymerization inhibitors or antioxidants were used, but the polymerization could not be suppressed in a 40°C atmosphere, resulting in gelation, or the polymerization was suppressed too strongly, resulting in a surface curability rating of "Poor." From these results, it was discovered that the component (D) of the present invention uniquely achieves both storage stability and surface curability.

[0085] Reference Examples 1 to 3 were prepared using different oligomers. The compositions were prepared by weighing components (A), (B), (D), and others into a stirring vessel and stirring for 30 minutes. The mixture was then stirred for 30 minutes while vacuum degassing. Finally, component (C) was weighed and added to the stirring vessel, followed by stirring for 30 minutes. Detailed amounts are shown in Table 5, with all values ​​expressed in parts by mass. The results of the surface curability test are also shown below.

[0086]

[0087] Comparing Example 6 with Reference Examples 1 to 3, it is clear that, with regard to surface curing properties, it is preferable for the urethane acrylate oligomer to contain three or more functional groups per molecule.

[0088] The present invention provides a photocurable composition that contains a polythiol compound and yet has both surface curability and storage stability (suppression of viscosity change). In particular, since viscosity change affects application in nail treatments, the present invention allows stable application and can be used, particularly as a top coat.

[0089] This application is based on Japanese Patent Application No. 2021-184527, filed on November 12, 2021, the disclosure of which is hereby incorporated by reference in its entirety.

Claims

1. A photocurable composition containing components (A) to (D). Component (A): A compound having a (meth)acryloyl group. Component (B): A polythiol compound. Component (C): A photoinitiator. Component (D): A preservative stabilizer having a pKa of 1.0 to 4.0 (not containing component (A)).

2. The photocurable composition according to claim 1, wherein the component (D) is a phosphorus compound.

3. The phosphorus compound is a phosphonic acid compound R １ -P(=O)(OR ２ ) ２ (wherein R １ is hydrogen or an organic group not bonded to a phosphorus atom by an oxygen atom, and R ２ are each independently hydrogen or an organic group) The photocurable composition according to claim 2.

4. The photocurable composition according to claim 1, wherein the component (D) is at least one selected from the group consisting of phosphoric acid, oxalic acid, 2-ethylhexyl (2-ethylhexyl) phosphonate, phenylphosphonic acid, vinylphosphonic acid, and methylphosphonic acid.

5. The photocurable composition according to claim 1, wherein the component (D) is contained in an amount of 0.01 to 10.0% by mass based on the entire composition.

6. The photocurable composition according to claim 1, which does not contain a preservative stabilizer other than the component (D) in the composition.

7. The photocurable composition according to claim 1, wherein the component (B) is contained in an amount of 0.1 to 50 parts by mass and the component (C) is contained in an amount of 0.1 to 10 parts by mass with respect to 100 parts by mass of the component (A).

8. The photocurable composition according to claim 1, wherein the component (A) consists of a (meth)acrylate oligomer and a (meth)acrylate monomer.

9. The photocurable composition according to claim 8, wherein the (meth)acrylate monomer consists only of a monofunctional (meth)acrylate and / or a difunctional (meth)acrylate.

10. The photocurable composition according to claim 9, wherein the monofunctional (meth)acrylate is a monofunctional (meth)acrylate having a hydroxyl group.

11. The photocurable composition according to claim 9, wherein the bifunctional (meth)acrylate is dimethyloltricyclodecane diacrylate.

12. The photocurable composition according to claim 1, which is a photocurable composition used for nails or artificial nails.

13. The photocurable composition used for nails or artificial nails according to claim 12, which is a photocurable composition for a top coat.