Photocurable composition for nails or artificial nails

Abstract

The purpose of the present invention is to provide a photocurable composition for nails or artificial nails, which has both storage stability and photocurability while suppressing heat generation, and which exhibits gloss on the surface of a cured product. The present invention pertains to a composition containing components (A)-(D), the composition containing 30-70 parts by mass of component (B) and 10-80 parts by mass of component (C) per 100 parts by mass of component (A), the component (A) being a urethane-modified (meth) acrylate oligomer having a weight-average molecular weight of 3000-6000 and containing 3-5 (meth) acryloyl groups per molecule; component (B): a (meth) acrylate containing one or more (meth) acryloyl groups per molecule excluding component (A); component (C): a polythiol compound; component (D): a photoinitiator.

Description

Technical Field

[0001] The present invention relates to a photocurable composition for nails or artificial nails. Background Art

[0002] So-called gel nails have the property of obtaining a cured product that exhibits gloss on the surface by irradiation with light, and thus are used for decoration of nails or artificial nails. For the application of nails or artificial nails, it is carried out by directly or indirectly applying gel nails to a person's natural nails and irradiating them with light to cure them. The invention of gel nails is described in Japanese Patent Application Laid-Open No. 2017-210475. It is known that by adding a polythiol compound to a compound having a (meth)acryloyl group, the photocurability of gel nails is improved, and accordingly, it is difficult to be affected by oxygen inhibition even at the interface in contact with oxygen and the surface curability is improved. Summary of the Invention

[0003] However, when gel nails contain a polythiol compound, it has been found that it is difficult to make the surface of the cured product exhibit gloss or maintain the durability of the gloss. In addition, it is known that since the photocurability increases due to the inclusion of a polythiol compound in gel nails, the viscosity of gel nails tends to increase and the storage stability decreases when placed before application. Adding a polymerization inhibitor or the like can improve the storage stability, but there is a problem of affecting the surface gloss of the cured product. Further, at the stage of light irradiation during nail application, there is a case where gel nails generate heat together with photocuring, and the subject feels a sense of pressure due to the heat.

[0004] Therefore, an object of the present invention is to provide a photocurable composition for nails or artificial nails that has storage stability and photocurability while suppressing heat generation (curing heat) and exhibits gloss on the surface of the cured product.

[0005] The inventors of the present invention conducted intensive studies to achieve the above object, and as a result, completed the present invention as a photocurable composition.

[0006] The gist of the present invention will be described below. The first embodiment of the present invention is a photocurable composition for nails or artificial nails, which contains components (A) to (D), and contains 30 to 70 parts by mass of component (B) and 10 to 80 parts by mass of component (C) with respect to 100 parts by mass of component (A).

[0007] (A) component: a urethane-modified (meth)acrylate oligomer having a weight average molecular weight of 3000 to 6000 and containing 3 to 5 (meth)acryloyl groups per molecule;

[0008] (B) component: a (meth)acrylate having one or more (meth)acryloyl groups per molecule (excluding component (A));

[0009] (C) Component: Polythiol compound;

[0010] (D) Component: Photoinitiator.

[0011] In the second embodiment of the present invention, regarding the photocurable composition for nails or artificial nails described in the first embodiment, the (A) component has a polyether backbone.

[0012] In the third embodiment of the present invention, regarding the photocurable composition for nails or artificial nails described in the first embodiment or the second embodiment, the (B) component is composed only of monofunctional (meth)acrylate and / or difunctional (meth)acrylate.

[0013] In the fourth embodiment of the present invention, regarding the photocurable composition for nails or artificial nails described in the third embodiment, the monofunctional (meth)acrylate is a monofunctional (meth)acrylate having a hydroxyl group.

[0014] In the fifth embodiment of the present invention, regarding the photocurable composition for nails or artificial nails described in the third embodiment or the fourth embodiment, the difunctional (meth)acrylate is dimethylol tricyclodecane diacrylate.

[0015] In the sixth embodiment of the present invention, regarding the photocurable composition for nails or artificial nails described in any one of the first to fifth embodiments, a phosphorus compound is further contained as a storage stabilizer.

[0016] In the seventh embodiment of the present invention, regarding the photocurable composition for nails or artificial nails described in the sixth embodiment, the phosphorus compound is a phosphonic acid compound.

[0017] In the eighth embodiment of the present invention, regarding the photocurable composition for nails or artificial nails according to any one of the first to seventh embodiments, the photocurable composition for nails or artificial nails is used to form a top coat.

[0018] Through the present invention, a photocurable composition can be provided that has storage stability and photocurability while suppressing heat generation (curing heat) and exhibits gloss on the surface of the cured product. Detailed Embodiments

[0019] The embodiments of the present invention will be described below. It should be noted that the present invention is not limited to the following embodiments. In addition, in this specification, unless otherwise specified, the operations and the measurement of physical properties are carried out under the conditions of room temperature (20°C or more and 25°C or less) / relative humidity of 40% RH or more and 50% RH or less. In addition, "A and / or B" means including each of A and B and all combinations of one or more, specifically, it means at least one of A and B, and means the combination of A, B, and A and B. It should be noted that in this specification, "X to Y" means that the values (X and Y) described before and after are used as the lower limit value and the upper limit value, and means "X or more and Y or less". When there are multiple "X to Y" described, for example, when described as "X1 to Y1, or X2 to Y2", each value is disclosed as the upper limit, each value is disclosed as the lower limit, and the combinations of their upper limits and lower limits are all disclosed (that is, it becomes a legal basis for amendment). Specifically, amendments of X1 or more, amendments of Y2 or less, amendments of X1 or less, amendments of Y2 or more, amendments of X1 to X2, amendments of X1 to Y2, etc. are all necessarily regarded as legal.

[0020] In one aspect of the present invention, there is provided a photocurable composition for nails or artificial nails, which contains components (A) to (D), and contains 30 to 70 parts by mass of component (B) and 10 to 80 parts by mass of component (C) with respect to 100 parts by mass of component (A).

[0021] Component (A): A urethane-modified (meth)acrylate oligomer having a weight average molecular weight of 3000 to 6000 and containing 3 to 5 (meth)acryloyl groups per molecule.

[0022] Component (B): A (meth)acrylate having one or more (meth)acryloyl groups per molecule (excluding component (A)).

[0023] Component (C): A polythiol compound.

[0024] Component (D): A photoinitiator. Thus, it is possible to provide a photocurable composition containing a compound having a (meth)acryloyl group and a polythiol compound, which has storage stability and photocurability while suppressing heat generation during photocuring and exhibits gloss on the surface of the cured product. That is, the photocurable composition of the present invention suppresses heat generation during photocuring, has excellent storage stability, high photocurability, and exhibits high glossiness on the surface of the cured product. It should be noted that in the present invention, "gloss" means exceeding 80% in the measurement of glossiness described later. In contrast, "luster" means that when visually confirming the surface from multiple directions, the surface is flat and smooth from any direction, indicating a state where gloss can be confirmed from any direction.

[0025] The present invention will be described in detail below. As the component (A) that can be used in the present invention, it is a urethane-modified (meth)acrylate oligomer having a weight-average molecular weight of 3,000 to 6,000 and containing 3 to 5 (meth)acryloyl groups per molecule. Hereinafter, acryloyl group and methacryloyl group are collectively referred to as (meth)acryloyl group. Here, in the present specification, the weight-average molecular weight refers to the weight-average molecular weight in terms of polystyrene measured by gel permeation chromatography.

[0026] The urethane-modified (meth)acrylate oligomer is a (meth)acrylate oligomer having a urethane bond, and any oligomer having at least one urethane bond and at least one (meth)acryloyl group can be used. When the urethane (meth)acrylate oligomer is added, the adhesion to nails or artificial nails is improved, and the curability and strength of the photocurable composition (coating film) are improved. An "oligomer" refers to a polymer (a polymer having a molecular weight exceeding 1,000) in which monomer units (including monomer units other than (meth)acrylate monomers) are repeated about 2 to several tens of times. The urethane-modified (meth)acrylate oligomer can be synthesized by a known method. For example, a method of forming a urethane bond from a polyol and a polyisocyanate and attaching a compound having a hydroxyl group and a (meth)acryloyl group or (meth)acrylic acid to the remaining isocyanate group is known. Based on the component (A) of the present invention, it is a urethane-modified acrylate oligomer having a weight-average molecular weight of 3,000 to 6,000 and containing 3 to 5 acryloyl groups per molecule. Thereby, the durability of the gloss of the cured product obtained by curing the photocurable composition is improved, and the photocurability becomes good.

[0027] As the polyol, a polyol compound having two or more hydroxyl groups in the molecule can be mentioned. Specifically, examples of the polyol include polyether polyol, polyester polyol, caprolactone diol, bisphenol polyol, polyisoprene polyol, hydrogenated polyisoprene polyol, polybutadiene polyol, hydrogenated polybutadiene polyol, castor oil polyol, polycarbonate diol, etc. Among them, from the viewpoint of exhibiting glossiness, since a polyether skeleton is introduced into the component (A), the above polyol is preferably a polyether diol. They can be used alone or in combination of two or more. In one embodiment, the above polyol may have three or more, four or more, or five or more hydroxyl groups in the molecule, and may have ten or less, eight or less, six or less, four or less, or three or less hydroxyl groups.

[0028] As the polyisocyanate, compounds having two or more isocyanate groups in the molecule can be mentioned. Specifically, aromatic polyisocyanates, alicyclic polyisocyanates, and aliphatic polyisocyanates can be mentioned, but are not limited thereto. As the aromatic polyisocyanate, 2,4-benzylidene diisocyanate, 2,6-benzylidene diisocyanate, 1,3-benzenedimethyl diisocyanate, 1,4-benzenedimethyl diisocyanate, tetramethylbenzenedimethyl diisocyanate, diphenylmethane diisocyanate, naphthalene-1,5-diisocyanate, triphenylmethane triisocyanate, etc. can be mentioned. As the alicyclic polyisocyanate, isophorone diisocyanate, bis(4-isocyanatocyclohexyl)methane, 1,3-bis(isocyanatomethyl)cyclohexane, 1,4-bis(isocyanatomethyl)cyclohexane, norbornane diisocyanate, bicycloheptane triisocyanate, etc. can be mentioned. As the aliphatic polyisocyanate, hexamethylene diisocyanate, 1,3,6-hexamethylene triisocyanate, 1,6,11-undecatriisocyanate, etc. can be mentioned. Among them, diisocyanates such as isophorone diisocyanate and hexamethylene diisocyanate are preferred. In this specification, "aromatic polyisocyanate" means a polyisocyanate having an aromatic ring in the structure. In this specification, "alicyclic polyisocyanate" means a polyisocyanate having an alicyclic structure in the structure. In this specification, "aliphatic polyisocyanate" means a polyisocyanate in which the structure other than the isocyanate structure is composed of linear or branched aliphatic groups.

[0029] Examples of the compound having a hydroxyl group and a (meth)acryloyl group include mono(meth)acrylates of diols such as ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, and polyethylene glycol, and mono(meth)acrylates or di(meth)acrylates of triols such as trimethylolethane, trimethylolpropane, and glycerin. They can be used alone or in combination of two or more.

[0030] As the component (A), a polyether backbone urethane (meth)acrylate oligomer is preferably used, and a polyether backbone difunctional urethane (meth)acrylate oligomer is more preferably used. However, other urethane (meth)acrylate oligomers such as polyester backbone urethane (meth)acrylate oligomers, polycaprolactone backbone urethane (meth)acrylate oligomers, and polycarbonate backbone urethane (meth)acrylate oligomers can also be used in combination.

[0031] (Component (A) contains 3 to 5 (meth)acryloyl groups per molecule and has a weight-average molecular weight of 3000 to 6000. Thus, it does not generate heat during photocuring and can be cured rapidly. Furthermore, no stickiness remains on the surface of the cured product while presenting luster. In one embodiment, component (A) contains 3 to 4 (meth)acryloyl groups per molecule. In one embodiment, component (A) contains 3 to 5, or 3 to 4 methacryloyl groups per molecule. In one embodiment, the weight-average molecular weight of component (A) is 4000 to 5500, or 4900 to 5500. In one embodiment, component (A) has a polyether backbone in its structure. These component (A)s can be used alone as one kind, or in combination of two or more kinds. In the case of using two or more kinds in combination, the content of component (A) is the total amount.)

[0032] In one embodiment, the 3 to 5 (meth)acryloyl groups contained in component (A) are located at both ends sandwiching the repeating structure. In one embodiment, the (meth)acryloyl groups contained in component (A) are 3 or 4. In one embodiment, component (A) is a compound represented by the following Chemical Formula 1:

[0033] [Chemical Formula 1]

[0034]

[0035] In the formula,

[0036] L 1 is a group of alkylene, cycloalkylene, arylene, or a combination thereof,

[0037] L 2 is alkylene, arylene, polyoxyalkylene (*-[A 1 -O] n2 -A 1 -*), poly(oxycarbonylalkylene) group, poly(oxycarbonyloxyalkylene) group, or a combination thereof,

[0038] At this time, A 1 is ethylene, propylene, trimethylene, or tetramethylene, n2 is an integer from 0 to 100,

[0039] X 1 and X 2 are each independently the structure shown below,

[0040] [Chemical Formula 2]

[0041]

[0042] In the formula,

[0043] R 1 ~R 3and R 5 are each independently a hydrogen atom or a methyl group,

[0044] R 4 is a hydrogen atom, a methyl group, or an ethyl group,

[0045] A 2 is ethylene, propylene, trimethylene, or tetramethylene,

[0046] When either one of X 1 and X 2 has the structure represented by any one of (2) and (4), the other is the structure represented by (3),

[0047] n 1 is an integer from 1 to 100.

[0048] In one embodiment, L in the above chemical formula (1) 2 contains a polyoxyalkylene group. When the component (A) contains a molecule having such a structure, the cured product obtained by photocuring the photocurable composition has a glossy surface. In one embodiment, L in the above chemical formula (1) 2 is composed only of a polyoxyalkylene group.

[0049] In the present specification, * represents a bonding site to other atoms or atomic groups. In the present specification, "alkylene" means a substituted or unsubstituted alkylene group having 1 to 20 carbon atoms, 1 to 15 carbon atoms, 1 to 10 carbon atoms, 2 to 8 carbon atoms, or 2 to 4 carbon atoms. Examples of the alkylene group include, but are not limited to, methylene, ethylene, propylene, trimethylene, tetramethylene, pentamethylene, and hexamethylene.

[0050] In the present specification, "oxyalkylene" means a group represented by the following formula (5),

[0051] [Chemical formula 3]

[0052] *-O-A 3 -* (5)

[0053] In the formula, A 3 is an alkylene group. Examples of the oxyalkylene group include, but are not limited to, oxyethylene, oxypropylene, oxytrimethylene, and oxytetramethylene.

[0054] In the present specification, "arylene" means a substituted or unsubstituted arylene group having 6 to 30 carbon atoms, 6 to 20 carbon atoms, 6 to 15 carbon atoms, or 6 to 10 carbon atoms. Examples of the arylene group include, but are not limited to, phenylene, tolylene, xylylene, and naphthylene.

[0055] In this specification, "substituted" means that a hydrogen atom is replaced by another atom or substituent. As the above-mentioned atom or substituent, unless otherwise defined, a halogen atom can be mentioned; an alkyl group having 1 to 20 carbon atoms, 1 to 10 carbon atoms, or 1 to 6 carbon atoms; an alkoxy group having 1 to 20 carbon atoms, 1 to 10 carbon atoms, or 1 to 6 carbon atoms; an aryl group having 6 to 30 carbon atoms, 6 to 20 carbon atoms, 6 to 15 carbon atoms, or 6 to 10 carbon atoms; or a combination thereof, but is not limited to these.

[0056] As a specific example, Art Resin KY-11 manufactured by Negami Kogyo Co., Ltd. etc. can be mentioned, but is not limited to these.

[0057] In one embodiment, regarding the photocurable composition for nails or artificial nails, the content of the component (A) relative to the total mass of the photocurable composition for nails or artificial nails is 30% by mass or more, 40% by mass or more, or 45% by mass or more. In one embodiment, the content of the component (A) relative to the total mass of the photocurable composition for nails is 70% by mass or less, 60% by mass or less, 55% by mass or less, or 51% by mass or less. For example, the content of the component (A) relative to the total mass of the photocurable composition for nails or artificial nails is preferably 30% by mass or more and 65% by mass or less, more preferably 35% by mass or more and 60% by mass or less, and further preferably 40% by mass or more and 56% by mass or less.

[0058] The component (B) that can be used in the present invention is a (meth)acrylate containing one or more (meth)acryloyl groups per molecule. However, the component (A) is excluded. As the component (B), any compound having a (meth)acryloyl group can be used. Specifically, as the compound having a (meth)acryloyl group, it refers to a (meth)acrylate monomer or a (meth)acrylate oligomer. In one embodiment, the molecular weight of the monomer is 1000 or less. In the present specification, an "oligomer" refers to a compound having a structure in which a plurality of repeating units are bonded and having a molecular weight or a weight-average molecular weight exceeding 1000. Unless otherwise specified, even if the compound itself further forms a polymer by polymerization or the like, it is not called a "monomer" but an "oligomer". The molecular weight of the monomer used as the component (B) can be 1000 or less, 800 or less, 500 or less, or 400 or less. In one embodiment, the weight-average molecular weight (or molecular weight) of the oligomer used as the component (B) can be 2000 or more, 3000 or more, 4000 or more, 5000 or more, 6000 or more, 7000 or more, 10000 or more, 20000 or more, or 30000 or more, and can be 500000 or less, 300000 or less, 200000 or less, or 100000 or less. The component (B) is preferably liquid at 25°C in an atmosphere, and can be used as long as it has good compatibility with the components (A) and (C) of the present invention.

[0059] As specific examples of the (meth)acrylate oligomer used as the component (B), there can be mentioned a urethane-modified (meth)acrylate oligomer other than the component (A), a (meth)acrylate oligomer having an ester bond in the molecule, a (meth)acrylate oligomer having an ether bond in the molecule, an epoxy-modified (meth)acrylate oligomer, etc. The main skeletons can include bisphenol A, novolac phenol, polybutadiene, polyester, polyether, etc., but are not limited thereto. In one embodiment, the main skeleton of the (meth)acrylate oligomer used as the component (B) contains structures such as bisphenol A, novolac, polybutadiene, polyester, polyether, etc., but is not limited thereto. In addition, the component (A) that can be used in the present invention also includes a compound having one or more epoxy groups and one or more (meth)acryloyl groups in one molecule.

[0060] In one embodiment, the (meth)acrylate oligomer used as the component (B) contains one or two acryloyl groups in one molecule. In one embodiment, the (meth)acrylate oligomer used as the component (B) can contain two or more, three or more, six or more, or eight or more acryloyl groups in one molecule, and can contain 30 or less, 20 or less, or 15 or less acryloyl groups.

[0061] Regarding the urethane-modified (meth)acrylate oligomer other than the component (A) used as the component (B), it is a urethane-modified (meth)acrylate oligomer having a weight-average molecular weight lower than 3000 or higher than 6000, or less than 3 or more than 5 (meth)acryloyl groups per molecule.

[0062] Regarding the (meth)acrylate oligomer having an ester bond used as the component (B), the synthesis of adding acrylic acid to the unreacted hydroxyl group by forming an ester bond from a polyol and a polycarboxylic acid is known, but the synthesis method is not limited to this. Specifically, examples include Aronix (registered trademark, the same in this specification) M-6100, M-6200, M-6250, M-6500, M-7100, M-7300K, M-8030, M-8060, M-8100, M-8530, M-8560, M-9050, etc. manufactured by Toagosei Co., Ltd., and UV-3500BA, UV-3520TL, UV-3200B, UV-3000B, etc. manufactured by Nippon Synthetic Chemical Industry Co., Ltd., but are not limited to these.

[0063] Regarding the (meth)acrylate oligomer having an ether bond used as the component (B), a synthesis method of adding acrylic acid to the hydroxyl group of a polyether polyol or the hydroxyl group of a polyether polyol having an aromatic such as bisphenol is known, but the synthesis method is not limited to this. In addition, it may have an ether bond and a urethane bond in the molecule, and may be a urethane-modified (meth)acrylate oligomer having an ether bond. As specific examples, there are UV-6640B, UV-6100B, UV-3700B, etc. manufactured by Nippon Synthetic Chemical Industry Co., Ltd., Light (Meth)acrylates 3EG-A, 4EG-A, 9EG-A, 14EG-A, PTMGA-250, BP-4EAL, BP-4PA, BP-10EA, etc. manufactured by Kyoeisha Chemical Co., Ltd., and EBECRYL3700, etc. manufactured by Daicel-Allnex Co., Ltd., but are not limited to these.

[0064] Regarding the epoxy-modified (meth)acrylate oligomer used as the component (B), it can be synthesized by ring-opening polymerization of the glycidyl group of a polyfunctional glycidyl ether compound with (meth)acrylic acid or the like, but is not limited to these. As the main chain of the polyfunctional glycidyl ether, various skeletons such as bisphenol A type, bisphenol F type, and novolac type can be used. As specific examples of the epoxy-modified acrylic oligomer, there are Epoxy Esters3000A, 3002A, etc. manufactured by Kyoeisha Chemical Co., Ltd., and EBECRYL3700, etc. manufactured by Daicel Corporation, but are not limited to these.

[0065] Regarding the (meth)acrylate monomer used as the component (B), monofunctional, difunctional, and trifunctional (meth)acrylate monomers may be included. In addition, as the component (B), a single monomer or a combination of multiple monomers may be used. Herein, in this specification, the term "functional group", unless otherwise specified, refers to a group containing a (meth)acryloyl group. For example, the terms "monofunctional", "difunctional", and "trifunctional" respectively refer to terms used to modify a compound having 1, 2, or 3 groups containing a (meth)acryloyl group in the molecule. In one embodiment, the group containing a (meth)acryloyl group may be a (meth)acryloyloxy group.

[0066] Specific examples of the monofunctional (meth)acrylate monomer used as the component (B) include lauryl (meth)acrylate, stearyl (meth)acrylate, ethyl carbitol (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, caprolactone-modified tetrahydrofurfuryl (meth)acrylate, cyclohexyl (meth)acrylate, dicyclopentyl (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, 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 (or also referred to as 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, N,N-diethylaminoethyl (meth)acrylate, etc., but are not limited thereto. It is preferred to include a monofunctional monomer having a hydroxyl group in one molecule of the compound used as the component (B). Specifically, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, etc. may be mentioned, but are not limited thereto.

[0067] Regarding the monofunctional (meth)acrylate monomer used as the component (B), (meth)acrylate monomers having an acidic group can also be mentioned. In one embodiment, the (meth)acrylate monomer having an acidic group refers to, in particular, carboxylic acids, phosphoric acids, etc. having a (meth)acryloyl group in the molecule. Examples of the carboxylic acid having a (meth)acryloyl group in the molecule include (meth)acrylic 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, 4-(meth)acryloyloxybutyl phthalic acid, etc. Examples of the phosphoric acid having a (meth)acryloyl group in the molecule include 2-ethylhexyl acid phosphate, 2-hydroxyethyl (methacrylate) acid phosphate, dibutyl phosphate, etc., but are not limited thereto. For the purpose of improving durability, it is preferable to contain a (meth)acrylate monomer having an acidic group.

[0068] As specific examples of the difunctional (meth)acrylate monomer used as the component (B), 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol 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, ethylene oxide-modified 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, diacryloyl isocyanurate, etc. can be mentioned, but are not limited thereto. The difunctional (meth)acrylate monomer used as the component (B) includes compounds having a ring structure and compounds not having a ring structure. In one embodiment, the difunctional (meth)acrylate monomer used as the component (B) has a ring structure. As the ring structure, an alicyclic structure, an aromatic hydrocarbon ring structure, a heterocyclic structure, etc. can be mentioned. If the improvement of curability is considered, it is preferable to contain a difunctional (meth)acrylate monomer having an alicyclic structure. As the alicyclic structure, a monocyclic structure or a polycyclic structure can be mentioned. The polycyclic structure includes a ring-fused structure, and as the difunctional (meth)acrylate monomer used as the component (B), a monomer having a ring-fused structure can be preferably used. As the difunctional (meth)acrylate monomer having an alicyclic structure, dimethylol tricyclodecane di(meth)acrylate is preferably used. Here, the alicyclic structure means the structure of a cyclic aliphatic hydrocarbon, and specifically, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, butylhexyl, methylcyclohexyl, dimethylcyclohexyl, cycloheptyl, methylcycloheptyl, cyclooctyl, cyclononyl, cyclodecyl and other cycloalkyl groups, hydronaphthyl, 1-adamantyl, 2-adamantyl, norbornyl, methylnorbornyl, isobornyl, dicyclopentenyl, dicyclopentyl, dicyclopentenyl oxyethyl, tricyclodecane, etc. can be mentioned.

[0069] As specific examples of the trifunctional (meth)acrylate monomer, 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, tris(acryloyloxyethyl)isocyanurate, etc. can be cited, but are not limited thereto.

[0070] From the viewpoint of imparting surface curability and gloss, the monofunctional (meth)acrylate monomer preferably contains a monofunctional (meth)acrylate having a hydroxyl group, and the difunctional (meth)acrylate monomer preferably contains dimethyloltricyclodecane diacrylate.

[0071] Component (B) preferably contains a monofunctional (meth)acrylate and / or a difunctional (meth)acrylate, more preferably consists only of a monofunctional (meth)acrylate and / or a difunctional (meth)acrylate, and most preferably consists only of a monofunctional (meth)acrylate and a difunctional (meth)acrylate. Further, from the viewpoint of suppressing heat generation (curing heat) during the treatment, component (B) preferably does not contain a (meth)acrylate having three or more functional groups.

[0072] Component (B) can be used alone as one kind, or two or more kinds can be used in combination. In one embodiment, component (B) contains a compound having one or two (meth)acryloyl groups in one molecule. Component (B) can consist only of a compound having one and / or two (meth)acryloyl groups in one molecule. Component (B) can consist only of monomers, or can also be a mixture of monomers and oligomers. As the monomers used as component (B), one kind can be used alone, or two or more kinds can be used in combination. As the oligomers used as component (B), one kind can be used alone, or two or more kinds can be used in combination. In the case of using two or more kinds in combination, the content of component (B) refers to the total amount.

[0073] In a preferred embodiment, component (B) contains a (meth)acrylate monomer having 1 to 3 (meth)acryloyl groups per molecule. As the (meth)acrylate monomer, a (meth)acrylate monomer having 1 or 2 (meth)acryloyl groups per molecule is preferred. The (meth)acrylate monomer preferably contains at least one selected from the group consisting of a (meth)acrylate monomer having a hydroxyl group, a (meth)acrylate monomer having an acidic group, and a (meth)acrylate monomer having an alicyclic structure. Further, the (meth)acrylate monomer more preferably contains at least one selected from the group consisting of a (meth)acrylate monomer having a hydroxyl group and a (meth)acrylate monomer having an alicyclic structure. That is, component (B) preferably contains at least one selected from the group consisting of a (meth)acrylate monomer having a hydroxyl group and having 1 or 2 (meth)acryloyl groups and a (meth)acrylate monomer having an alicyclic structure and having 1 or 2 (meth)acryloyl groups.

[0074] When component (B) contains a (meth)acrylate monomer (b1) having a hydroxyl group and having 1 or 2 (meth)acryloyl groups and a (meth)acrylate monomer (b2) having an alicyclic structure and having 1 or 2 (meth)acryloyl groups, the mass ratio (b1:b2) of (b1) and (b2) is preferably from 99:1 to 50:50, more preferably from 95:5 to 65:45, and still more preferably from 90:10 to 70:30.

[0075] In a preferred embodiment, component (B) contains a urethane-modified (meth)acrylate oligomer other than component (A). As the urethane-modified (meth)acrylate oligomer, a urethane-modified (meth)acrylate oligomer having a weight average molecular weight of less than 3000 or more than 6000 and having less than 3 or more than 5 (meth)acryloyl groups per molecule is preferred; a urethane-modified (meth)acrylate oligomer having a weight average molecular weight of more than 6000 and having 1 or 2 (meth)acryloyl groups per molecule is more preferred.

[0076] As an embodiment, the component (B) contains at least one selected from the group consisting of a urethane-modified (meth)acrylate oligomer having a weight-average molecular weight of more than 6,000 and having one or two (meth)acryloyl groups per molecule, and a (meth)acrylate monomer having one or two (meth)acryloyl groups per molecule. In this case, the content of the urethane-modified (meth)acrylate oligomer is preferably 0.1 to 15 parts by weight, more preferably 0.5 to 10 parts by weight, still more preferably 1 to 8 parts by weight, and particularly preferably 1.5 to 5 parts by weight relative to 100 parts by weight of the component (A). Further, the content of the (meth)acrylate monomer is preferably 1 to 80 parts by weight, more preferably 5 to 70 parts by weight, still more preferably 10 to 65 parts by weight, and particularly preferably 20 to 60 parts by weight relative to 100 parts by weight of the component (A). When the component (B) contains a urethane-modified (meth)acrylate oligomer and a (meth)acrylate monomer, the mass ratio of the urethane-modified (meth)acrylate oligomer to the (meth)acrylate monomer is preferably 1:99 to 20:80, more preferably 2:98 to 15:85, still more preferably 3:97 to 10:90.

[0077] As an embodiment, the component (B) contains at least one selected from the group consisting of a urethane-modified (meth)acrylate oligomer having a weight-average molecular weight of more than 6,000 and having one or two (meth)acryloyl groups per molecule, a (meth)acrylate monomer having a hydroxyl group and having one or two (meth)acryloyl groups; and a (meth)acrylate monomer having an alicyclic structure and having one or two (meth)acryloyl groups.

[0078] In the photocurable composition of the present invention, the content of the component (B) is 30 to 70 parts by weight relative to 100 parts by weight of the component (A), and most preferably the content of the component (B) is 40 to 60 parts by weight. When the content of the component (B) is 30 parts by weight or more, the viscosity of the composition is reduced and the application is easy, and when the content of the component (B) is 70 parts by weight or less, the curability is good. When the component (B) contains a monofunctional (meth)acrylate and a difunctional (meth)acrylate, the mass ratio of the monofunctional (meth)acrylate to the difunctional (meth)acrylate is preferably 1:1 to 4:1, more preferably 2:1 to 3:1.

[0079] In the photocurable composition of the present invention, the content of the (meth)acrylate oligomer used as the component (B) may be 0 to 20% by mass or 5 to 10% by mass relative to the total mass of the component (B). The content of the (meth)acrylate oligomer used as the component (B) may be 0 to 10% by mass, 0.5 to 5% by mass, or 1 to 3% by mass relative to the total mass of the photocurable composition.

[0080] In the photocurable composition of the present invention, the content of the monofunctional (meth)acrylate monomer used as the component (B) can be 50 to 100% by mass or 60 to 80% by mass based on the total mass of the component (B). The content of the monofunctional (meth)acrylate monomer used as the component (B) can be 10 to 30% by mass or 15 to 25% by mass based on the total mass of the photocurable composition.

[0081] The content of the difunctional (meth)acrylate monomer used as the component (B) can be 0 to 40% by mass or 10 to 30% by mass based on the total mass of the component (B). The content of the difunctional (meth)acrylate monomer used as the component (B) can be 0 to 30% by mass or 5 to 20% by mass based on the total mass of the photocurable composition.

[0082] The component (C) that can be used in the present invention is a polythiol compound. The component (C) is not particularly limited as long as it has two or more thiol groups in one molecule. It can be used alone, or two or more kinds can be used in combination. In one embodiment, the component (C) has two or three or four or more thiol groups in one molecule. From the viewpoint of improving the surface curability, the component (C) preferably has three thiol groups in one molecule or preferably has four or more thiol groups. In addition, from the viewpoint of improving the storage stability, the component (C) preferably has two or three thiol groups in one molecule. Specific examples of the component (C) include aliphatic polythiol compounds, aromatic polythiol compounds, polythiol compounds having a sulfide bond, etc., but are not limited thereto. When the component (C) is an aliphatic polythiol group, it has a primary thiol group, a secondary thiol group, and / or a tertiary thiol group. From the viewpoint of improving the surface curability, it preferably has a primary thiol group and / or a secondary thiol group, and more preferably has a primary thiol group. In one embodiment, all the thiol groups in the component (C) are primary thiol groups and / or secondary thiol groups, and preferably all are primary thiol groups.

[0083] Examples of the aliphatic polythiol compound having two thiol groups include, but are not limited to, 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, 1,4-cyclohexanedithiol, 1,4-bis(mercaptomethyl)cyclohexane, 1,1-cyclohexanedithiol, 1,2-cyclohexanedithiol, bicyclo[2,2,1]heptane-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).

[0084] Examples of the aliphatic polythiol compound 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.

[0085] Examples of the aliphatic polythiol compound having four or more thiol groups include, but are not limited to, pentaerythritol tetra(2-mercaptoacetate), pentaerythritol tetra(3-mercaptopropionate), pentaerythritol tetra(3-mercaptobutyrate), and dipentaerythritol hexa-3-mercaptopropionate.

[0086] Examples of the aromatic polythiol compounds include, but are not limited to, 1,2-benzenedithiol, 1,3-benzenedithiol, 1,4-benzenedithiol, 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-mercaptovinyloxy)benzene, 1,3-bis(2-mercaptovinyloxy)benzene, 1,4-bis(2-mercaptovinyloxy)benzene, 1,2,3-benzenetrithiol, 1,2,4-benzenetrithiol, 1,3,5-benzenetrithiol, 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-mercaptovinyloxy)benzene, 1,2,4-tris(2-mercaptovinyloxy)benzene, 1,3,5-tris(2-mercaptovinyloxy)benzene, 1,2,3,4-benzenetetrathiol, 1,2,3,5-benzenetetrathiol, 1,2,4,5-benzenetetrathiol, 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, 1,2,3,5-tetrakis(2-mercaptoethyl)benzene, 1,2,4,5-tetrakis(2-mercaptoethyl)benzene, 1,2,3,4-tetrakis(2-mercaptovinyloxy)benzene, 1,2,3,5-tetrakis(2-mercaptovinyloxy)benzene, 1,2,4,5-tetrakis(2-mercaptovinyloxy)benzene, 2,2'-thiobiphenyl, 4,4'-thiobis-benzenethiol, 4,4'-dithiobiphenyl, 4,4'-dithiobibenzyl, 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, 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, etc.

[0087] Examples of the polythiol compound having a thioether 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.

[0088] Examples of the product of component (C) having a primary thiol group include, but are not limited to, PEMP, TMMP, TMMP-20P, DPMP, TEMPIC, etc. manufactured by SC Organic Chemistry Co., Ltd.

[0089] Specific examples of the component (C) having a secondary thiol group include, but are not limited to, pentaerythritol tetra(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 tri(3-mercaptobutyrate), trimethylolethane tri(3-mercaptobutyrate), trimethylolpropane tri(3-mercaptobutyrate), trimethylolethane tri(3-mercaptobutyrate), etc. Examples of the product include, but are not limited to, PEMP, etc. manufactured by SC Organic Chemistry Co., Ltd., and PE1, BD1, NR1, etc. of the KarenzMT (registered trademark) series manufactured by Showa Denko K.K.

[0090] The content of component (C) is 10 to 80 parts by mass, preferably 10 to 70 parts by mass, more preferably 15 to 65 parts by mass, further preferably 20 to 60 parts by mass, particularly preferably 22 to 55 parts by mass, and most preferably 25 to 50 parts by mass with respect to 100 parts by mass of component (A). When the content of component (C) is 10 parts by mass or more, the surface curability is improved, and when the content is 80 parts by mass or less, the storage stability is improved. When the content of component (C) is less than 10 parts by mass, the surface curability is insufficient, and when it exceeds 80 parts by mass, curing heat is generated, which may cause oppression to the user. In addition, the content of component (C) is preferably more than 8% and less than 30% by mass based on the total mass of the composition. When two or more kinds are used in combination, the content of component (C) is the total amount.

[0091] The component (D) that can be used in the present invention is a photoinitiator (that is, a photopolymerization initiator, which can be referred to as a "photoinitiator" in this specification). As the component (D), there is no limitation as long as it is a free radical photoinitiator that generates free radical species due to energy rays such as visible light, ultraviolet rays, X-rays, and electron rays. In one embodiment, the component (D) contains an ultraviolet type photoinitiator and / or a visible light type photoinitiator. Here, the ultraviolet type photoinitiator refers to a photopolymerization initiator that generates free radical species by absorbing ultraviolet rays, and the visible light type photoinitiator refers to a photoinitiator with the strongest light absorption in the visible light region.

[0092] As specific examples of the ultraviolet light initiator used as the component (D), there may be mentioned acetophenone-based compounds such as diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethyl 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, 2-hydroxy-2-methyl-1-[4-(1-methylethenyl)phenyl]acetone oligomer; benzoin-based compounds such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether; benzophenone-based compounds such as benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, 3,3',4,4'-tetrakis(tert-butylperoxycarbonyl)benzophenone, 2,4,6-trimethylbenzophenone, 4-benzoyl-N,N-dimethyl-N-[2-(1-oxo-2-propanoyloxy)ethyl]benzammonium bromide, (4-benzoylbenzyl)trimethylammonium chloride; thioxanthone-based compounds such as 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone, 2-(3-dimethylamino-2-hydroxy)-3,4-dimethyl-9H-thiothioxanthone-9-one-mesochloride, etc., but are not limited thereto. In addition, the visible light initiator used as the component (D) is an acylphosphine oxide-based photopolymerization initiator mainly containing a phosphorus atom. Specifically, there may be mentioned 2,4,6-trimethylbenzoyl-diphenyl-oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, etc., but are not limited to these. The component (D) may be used alone in one kind, or two or more kinds may be used in combination. In addition, when two or more kinds are used in combination, the component (D) may be used in combination of an ultraviolet light initiator and a visible light initiator. When two or more kinds are used in combination, the content of the component (D) is the total amount.

[0093] With respect to 100 parts by mass of component (A), the content of component (D) is preferably 0.1 to 20 parts by mass, more preferably 1 to 18 parts by mass, and still more preferably 5 to 15 parts by mass. When the content of component (D) is 0.1 part by mass or more, the photocurability can be maintained. On the other hand, when the content of component (D) is 20 parts by mass or less, thickening can be avoided during storage and the storage stability can be maintained. The visible light type photoinitiator is preferably contained in an amount of 0 to 70% by mass based on the total mass of component (D), and the cured product is less likely to yellow. In one embodiment, the visible light type photoinitiator is preferably contained in an amount of 10 to 60% by mass based on the total mass of component (D), and more preferably 30 to 50% by mass.

[0094] In the present invention, within the range not impairing the characteristics of the present invention, additives such as (meth)acrylamide monomers, storage stabilizers, coupling agents, inorganic fillers, organic fillers, colorants such as pigments and dyes, antioxidants, polymerization inhibitors, defoamers, leveling agents, and rheology control agents can be appropriately blended. By adding them, a composition or its cured product having excellent resin strength, workability, storage stability, etc. can be obtained.

[0095] In the present invention, (meth)acrylamide monomers can be added within the range not impairing the characteristics of the present invention. Specific examples include dimethyl(meth)acrylamide, (meth)acryloylmorpholine, diethyl(meth)acrylamide, etc., but are not limited to these. Although the exact reason is unknown, from the viewpoint of improving durability, the monomer preferably contains (meth)acrylamide monomers. In the present invention, as specific examples of the (meth)acrylamide monomer, DMAA, ACMO, DEAA, etc. manufactured by KJ CHEMICALS Co., Ltd. are known, but are not limited to these.

[0096] In the present invention, a storage stabilizer can be added within the range not impairing the characteristics of the present invention. The storage stabilizer is a storage stabilizer having a pKa (acid dissociation constant) of 1.0 to 4.0 and does not contain component (A) and component (B). More specifically, it is an inorganic acid and / or an organic acid having a pKa of 1.0 to 4.0. From the viewpoint of compatibility with other components, the storage stabilizer is preferably an organic acid. Although the exact reason is unknown, by adding it to the composition of the present invention, both the storage stability such as viscosity and the surface curability are improved. pKa is one of the indexes for quantitatively expressing the strength of an acid (the ease of dissociation of hydrogen ions), and the lower the pKa, the stronger the acid. pKa is known to be measurable by methods such as neutralization titration, spectrophotometry, capillary electrophoresis, etc. Among them, neutralization titration has high accuracy. A phosphorus compound as a storage stabilizer is particularly preferably used as the storage stabilizer. Here, phosphonic acid and phosphoric acid are collectively referred to as phosphorus compounds, but component (D) is excluded. The most preferred is a phosphonic acid compound. The phosphonic acid compound is represented by R 1-P(=O)(OR 2 ) 2 represents, where R 1 is hydrogen or an organic group not linked to the phosphorus atom through an oxygen atom, and R 2 are each independently hydrogen or an organic group. As the organic group, an alkyl group having 1 to 20 carbon atoms and an aromatic group having 6 to 20 carbon atoms can be mentioned. For example, a phenyl group, a hydrocarbon group, etc. can be mentioned, but it is not limited to these. The most preferred storage stabilizer is phenylphosphonic acid. The storage stabilizer can be used alone or in combination of multiple kinds. It is preferred that the composition does not contain storage stabilizers other than the above-mentioned storage stabilizer. Generally, phosphoric acid is represented as P(=O)(OH) 3 , which is different from H-P(=O)(OH) as phosphonic acid 2 .

[0097] As a specific example of the storage stabilizer, phosphoric acid (pKa = 1.83), oxalic acid (pKa = 1.04), phosphonic acid compounds. Particularly, as phosphonic acid compounds, phenylphosphonic acid (pKa = 1.83), vinylphosphonic acid (pKa = 2.11), methylphosphonic acid (pKa = 2.38), etc. can be mentioned, but it is not limited to these. The storage stabilizer can be used alone or in combination of multiple kinds. In addition, in order to avoid the reduction of storage stability due to viscosity, etc., it is preferred not to use organic acids with pKa greater than 4.0 in combination with the above-mentioned storage stabilizer other than the storage stabilizer

[0098] Relative to 100 parts by mass of component (A), it is preferred to add 0.01 to 5.0 parts by mass of the storage stabilizer, and particularly most preferably 0.01 to 2.0 parts by mass. When the content of the storage stabilizer is 0.01 part by mass or more, the viscosity change is suppressed, and when it is 5.0 parts by mass or less, the surface curability can be maintained. In addition, relative to the total mass of the composition, the content of the storage stabilizer is preferably 0.01 to 10.0 mass%. In the case of using two or more kinds in combination, the content of the storage stabilizer is the total amount

[0099] In the present invention, a coupling agent can be added within the range that does not impair the characteristics of the present invention. As the coupling agent, a silane coupling agent having both an epoxy group, a vinyl group, an acryloyl group or a methacryloyl group and a hydrolyzable silyl group, a polyorganosiloxane having a phenyl group and a hydrolyzable silyl group, and / or a polyorganosiloxane having an epoxy group and a hydrolyzable silyl group, etc. can be mentioned, but it is not limited to these. As a specific example of the silane coupling agent, allyltrimethoxysilane, vinyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-chloropropyltrimethoxysilane, etc. can be mentioned, but it is not limited to these

[0100] In the present invention, fillers such as inorganic fillers and organic fillers can be appropriately added within the range that does not impair the characteristics of the present invention. By adding fillers, not only can the viscosity / thixotropy be adjusted, but also the curability and toughness can be adjusted. Examples of inorganic fillers include alumina, silica, amorphous silica, etc., but are not limited thereto. On the other hand, examples of organic fillers include styrene fillers, rubber fillers, core-shell acrylic fillers, etc., but are not limited thereto. Specific products include FUSELEX E-1 manufactured by Ryosen Co., Ltd. as silica, AO-802 manufactured by Admafine Co., Ltd., etc., and Aerosil series such as 200 (untreated), R972 (dimethyl dichlorosilane-treated), R976 (dimethyl dichlorosilane-treated), RY200 (dimethyl silicone-treated), RX200 (hexamethyldisilazane-treated), R800 (octylsilane-treated), etc. manufactured by Nippon Aerosil Co., Ltd. of Japan as amorphous silica, but are not limited thereto.

[0101] There is no particular limitation on the method for preparing the nail photocurable composition of the present invention, and a conventionally well-known method can be appropriately adopted. For example, for the components (A), (B), (C), (D), and any optionally added components, a specified amount is weighed respectively, and then added to a mixing kettle successively or simultaneously in any order, and then mixed using a mixing means such as a planetary mixer, preferably while performing vacuum degassing. The preferred addition order is to add the component (D) last. By adding the component (D) last, the photopolymerization reaction can be prevented from occurring at an undesirable stage. At this time, there is no particular limitation on the manufacturing conditions, but it is preferably carried out under light-shielded conditions. The mixing temperature is preferably a temperature of 10 to 50°C, and further, the mixing time is preferably 0.1 to 5 hours.

[0102] When the nail or artificial nail photocurable composition of the present invention is used as a so-called gel nail, the treatment is performed according to the following steps. Before the treatment, the surface of a person's nail is polished with a file or the like, and dust, grease, moisture, etc. are removed using a nail-specific solvent mainly composed of ethanol. When applying the present invention, a coating film with a thickness of 100 to 300 μm in the uncured state is formed using a brush, a paintbrush, etc. A primer can be used in advance during the coating. As the irradiation device during curing, a commercially available LED lamp for gel nails or the like is used. In one embodiment, the wavelength of the light used for irradiating the light can be 200 to 800 nm, 250 to 700 nm, 280 to 600 nm, 300 to 500 nm, or 350 to 400 nm. The irradiation time is 15 seconds to 120 seconds, and preferably 20 to 70 seconds considering the influence on the fingers.

[0103] The photocurable composition for nails or artificial nails of the present invention preferably has a viscosity at 25°C of 10 Pa·s or less, more preferably 5 Pa·s or less, in consideration of the coatability during the application.

[0104] The photocurable composition for nails or artificial nails of the present invention can suppress heat generation (curing heat) during photocuring, that is, during the light irradiation process, and the subject receiving the treatment does not feel a sense of pressure due to heat. In one embodiment, the heat generation (curing heat) of the photocurable composition for nails or artificial nails of the present invention during the light irradiation process is evaluated by a sensitivity test. The sensitivity test can be carried out, for example, by the above-mentioned subject receiving the treatment according to the evaluation criteria of three stages of "no heat sensation", "slight heat", and "heat". In one embodiment, the temperature after rising due to heat generation (curing heat) during the light irradiation of the photocurable composition for nails or artificial nails of the present invention is preferably 50°C or less, more preferably less than 45°C, further preferably 40°C or less, and even more preferably 36°C or less. The above temperature can be measured by a non-contact thermometer, for example.

[0105] When a compound having a (meth)acryloyl group is polymerized by generating free radical species due to energy rays, it is known that the polymerization in the region in contact with oxygen is inhibited under the inhibitory action of oxygen. At this time, uncured components remain on the surface of the cured product, so in most cases, a rag or the like is used to wipe the uncured components after photocuring during the application to make it shiny. In particular, this tendency is strong in the top coat used for the outermost surface. However, the photocurable composition based on the present invention is hardly affected by oxygen inhibition during photocuring, so it is suitable for a wipe-free top coat with no uncured components remaining on the surface after curing.

[0106] The cured product obtained by photocuring the photocurable composition for nails or artificial nails according to the present invention preferably has an initial glossiness of 85% or more, more preferably 87% or more, and further preferably 88% or more. In addition, for the cured product obtained by photocuring the photocurable composition for nails or artificial nails according to the present invention, the glossiness after the abrasion test is preferably 83% or more, more preferably 85% or more, and further preferably 88% or more. At this time, the change in glossiness before and after the abrasion test is preferably 5.8% or less, more preferably 4.0% or less, further preferably 3.0% or less, and even more preferably 2.0% or less. In this specification, the abrasion test is carried out by the method described in the examples. In this specification, the measurement of glossiness can be obtained by the method described in the examples.

[0107] It should be noted that in the present invention, the value obtained by measuring the glossiness using a high-glossiness detector manufactured by Horiba, Ltd. serves as a reference for the glossiness of the cured product. However, whether there is gloss after visually evaluating the entire surface of the cured product can be regarded as a clear evaluation of the actual glossiness. Thus, whether the result of the surface gloss based on visual inspection is ○ or × is preferentially considered as the gloss evaluation. For example, when comparing the glossiness of multiple cured products with an ○ evaluation, the glossiness calculated by the high-glossiness detector becomes an index, and the degree of gloss can be compared. Similarly, when comparing the glossiness of multiple cured products with an × evaluation, the glossiness calculated by the high-glossiness detector becomes an index, and the degree of gloss can be compared.

[0108] Embodiment

[0109] Next, examples are given to illustrate the present invention in more detail, but the present invention is not limited to these examples.

[0110] [Examples 1 to 6, Comparative Examples 1 to 4]

[0111] To prepare the photocurable composition, the following components were prepared. (Hereinafter, the photocurable composition for nails or artificial nails will also be simply referred to as the composition.)

[0112] (A) component: a urethane-modified (meth)acrylate oligomer having a weight average molecular weight of 3000 to 6000 and containing 3 to 5 (meth)acryloyl groups per molecule

[0113] ■ Weight average molecular weight: 5000, polyether-based urethane acrylate oligomer with 3 functional groups (manufactured by Negami Kogyo Co., Ltd., ArtResin KY-11)

[0114] Urethane-modified (meth)acrylate oligomers other than the (A) component

[0115] ■ Weight average molecular weight: 38000, polyether urethane acrylate with 2 functional groups (Mitsubishi Chemical Corporation, UV-3700B Violet)

[0116] ■ Weight average molecular weight: 3500, polyether urethane acrylate with 2 functional groups (manufactured by Negami Kogyo Co., Ltd., Art Resin UN-6303)

[0117] ■ Weight average molecular weight: 4900, urethane acrylate oligomer with 10 functional groups (manufactured by Negami Kogyo Co., Ltd., Art Resin UN-904)

[0118] (B) component: (meth)acrylate having one or more (meth)acryloyl groups per molecule (excluding the (A) component)

[0119] ■ 2-Hydroxypropyl methacrylate (manufactured by Nippon Shokubai Co., Ltd., HPMA)

[0120] ■ Dicyclopentanyl dimethacrylate (manufactured by Kyoeisha Chemical Co., Ltd., Light Acrylate DCP-A)

[0121] (C) Component: Polythiol compound

[0122] ■ Trimethylolpropane tris(3-mercaptopropionate) (manufactured by SC Organic Chemicals Co., Ltd., TMMP-20P)

[0123] (D) Component: Photoinitiator

[0124] ■ 1-Hydroxycyclohexyl phenyl ketone (non-visible light type photoinitiator) (IRGACURE 184, manufactured by BASF)

[0125] ■ 2,4,6-Trimethylbenzoyl-diphenyl-phosphine oxide (visible light type photoinitiator) (LUCIRIN TPO, manufactured by BASF)

[0126] Storage stabilizer

[0127] ■ Phenylphosphonic acid (reagent)

[0128] Preparation Examples 1 to 6 and Comparative Examples 1 to 4. The composition was prepared by weighing the (A) component (and other oligomers), (B) component, (C) component, and storage stabilizer, charging them into a stirring kettle, and stirring for 30 minutes. Subsequently, stirring was carried out while performing vacuum degassing for 30 minutes. Finally, the (D) component was weighed and added to the stirring kettle, and stirring was carried out for 30 minutes. The detailed preparation amounts are shown in Table 1, and all values are expressed in parts by mass.

[0129] [Table 1]

[0130]

[0131] For Examples 1 to 6 and Comparative Examples 1 to 4, confirmation of storage stability, confirmation of the surface state of the cured product, confirmation of surface curability, measurement of glossiness, wear test, and confirmation of heat generation during treatment were carried out. The results are summarized in Table 2.

[0132] [Confirmation of storage stability]

[0133] 100 g of the composition was filled into a glass container, covered with a lid to make it airtight, and placed in a hot air drying oven at 60 °C for 3 days. Subsequently, the properties of the composition were visually confirmed according to the following evaluation criteria as "storage stability".

[0134] Evaluation criteria

[0135] 〇: Tilt the container to make it flowable

[0136] ×: Tilt the container to make it non-flowable (in the gelling state).

[0137] [Confirmation of the surface state of the cured product]

[0138] Coat a 2.0 mm thick × 25 mm wide × 100 mm long acrylic plate with a brush so that the thickness of the composition is 300 μm. Cure the composition by irradiating it with a nail UV lamp (rated voltage: 100 - 110V, 50 - 60Hz, power consumption: 36W, wavelength: 350 - 400 nm) for 30 seconds. Visually confirm the reflection on the LED stand according to the following evaluation criteria as "surface gloss".

[0139] Evaluation criteria

[0140] 〇: The surface has luster

[0141] ×: The surface has no luster.

[0142] [Confirmation of surface curability]

[0143] Coat a 2.0 mm thick × 25 mm wide × 100 mm long acrylic plate with a brush so that the thickness of the composition is 300 μm. Cure the composition by irradiating it with a nail UV lamp (rated voltage: 100 - 110V, 50 - 60Hz, power consumption: 36W, wavelength: 350 - 400 nm) for 30 seconds. Touch the surface with a cotton swab and visually confirm the state of the surface of the cured product at this time according to the following evaluation criteria as "surface curability".

[0144] Evaluation criteria

[0145] 〇: No stickiness of the components is generated on the surface

[0146] ×: Stickiness of the components is generated on the surface.

[0147] [Gloss measurement]

[0148] Using a test piece (size: thickness 0.8 mm × width 70 mm × length 150 mm) with a transparent amino alkyd coating electrodeposited on one side of SPCC-SD as the base material, apply the composition to the electrodeposited surface with a thickness of 100 μm, and irradiate it with a UV lamp for nails (rated voltage: 100 - 110V 50 - 60Hz power consumption: 36W, wavelength: 350 - 400 nm) for 30 seconds to cure the composition and make a test piece. Use a high gloss meter manufactured by Horiba, Ltd. to measure the "initial gloss (%)" of the surface of the test piece at an incident angle of 60° and a light receiving angle of 60°. For the appearance to have luster, the initial gloss is preferably 85% or more.

[0149] [Wear test]

[0150] For the test piece after the measurement in the gloss measurement, wipe the surface 100 times with a rag, and conduct the same measurement as the gloss measurement again as the "gloss after wear (%)". In addition, calculate the "gloss change rate (%)" through "gloss change rate (%)" = ("gloss after wear (%)" - "initial gloss (%)") / "initial gloss (%)" × 100. From the perspective of durability, the gloss after wear is preferably 85% or more. In addition, the gloss change rate is preferably -6.0 to 0.0%, and most preferably -3.0 to 0.0%.

[0151] [Confirmation of heat generation during treatment]

[0152] After filing the nails, remove the dust and grease on the nail surface with a nail-specific solvent (mainly ethanol). Apply the primer at a wet coating thickness of approximately 100 μm. The application is carried out with a brush. Subsequently, irradiate it with an LED lamp for nails (rated voltage: 100 - 110V 50 - 60Hz power consumption: 36W, wavelength: 350 - 400 nm) for 30 seconds to cure the composition. In the same way, apply the color coating agent and the top coating agent in sequence on the surface of the primer layer and cure them in sequence under the same conditions. The color coating agent uses Super Color EX manufactured by PREGEL (color: pastel peach), and the top coating layer uses each composition. For the fingernails of the same person (10), evaluate the "heat generation during treatment" according to the following evaluation criteria. Considering the pressing feeling of the subject, "〇" is preferred. Here, "during treatment" refers to the period of light irradiation for curing each composition to form the top coating layer.

[0153] Evaluation criteria

[0154] 〇: No heat sensation

[0155] △: Slight heat

[0156] ×: Heat

[0157] [Table 2]

[0158]

[0159] Comparing Examples 1 to 6 with Comparative Examples 1 and 2, it can be seen that the surface curability is improved by making the content of component (C) 10 to 80 parts by mass relative to 100 parts by mass of component (A). In addition, in Examples 1 to 6, a urethane-modified (meth)acrylate oligomer having a weight average molecular weight of 3000 to 6000 and containing 3 to 5 (meth)acryloyl groups per molecule was used as component (A), and compared with Comparative Examples 3 and 4 using urethane-modified (meth)acrylate oligomers other than this, the heat generation during the procedure was suppressed. Furthermore, in Examples 1 to 6, a lower change rate of gloss after wear was more likely to be seen compared with Comparative Example 2.

[0160] Industrial Applicability

[0161] The present invention is a photocurable composition that has both surface curability and storage stability despite containing polythiol. Particularly, when there is a viscosity change during the procedure in the nail art field, it can affect the coatability, but the photocurable composition based on the present invention enables a stable procedure. In addition, the present invention does not generate heat during the procedure and furthermore has good surface curability, and thus can be used as a non-wipe topcoat.

[0162] This application is based on Japanese Patent Application No. 2022-177268 filed on November 4, 2022, the entire disclosure of which is incorporated herein by reference.

Claims

1. A photocurable composition for nails or artificial nails, wherein, it contains components (A) to (D), and relative to 100 parts by mass of component (A), it contains 30 to 70 parts by mass of component (B) and 10 to 80 parts by mass of component (C), (A) component: a urethane-modified (meth)acrylate oligomer having a weight-average molecular weight of 3000 to 6000 and containing 3 to 5 (meth)acryloyl groups per molecule; (B) component: a (meth)acrylate having one or more (meth)acryloyl groups per molecule, and excluding component (A); (C) component: a polythiol compound; (D) component: a photoinitiator.

2. The photocurable composition for nails or artificial nails according to claim 1, wherein, the component (A) has a polyether backbone.

3. The photocurable composition for nails or artificial nails according to claim 1, wherein, the component (B) is composed only of a monofunctional (meth)acrylate and / or a difunctional (meth)acrylate.

4. The photocurable composition for nails or artificial nails according to claim 3, wherein, the monofunctional (meth)acrylate is a monofunctional (meth)acrylate having a hydroxyl group.

5. The photocurable composition for nails or artificial nails according to claim 3, wherein, the difunctional (meth)acrylate is dimethyloltricyclodecane diacrylate.

6. The photocurable composition for nails or artificial nails according to claim 1, wherein, further contains a phosphorus compound as a storage stabilizer.

7. The photocurable composition for nails or artificial nails according to claim 6, wherein, the phosphorus compound is a phosphonic acid compound.

8. The photocurable composition for nails or artificial nails according to claim 1, wherein, the photocurable composition for nails or artificial nails is used to form a top coat.

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