Photocurable artificial nail composition, artificial nail, and method for producing same

Abstract

To provide a photocurable artificial nail composition that suppresses heat pain during curing, suppresses yellowing (including yellowing before curing), and has color tone stability.SOLUTION: The photocurable artificial nail composition of the present invention includes a photopolymerization initiator and a polymerizable compound, wherein the photopolymerization initiator contains a compound represented by general formula (1), provided that the composition does not contain an α-hydroxyalkylphenone photopolymerization initiator, and the composition does not contain a peroxide thermal polymerization initiator. (In the general formula (1), R represents a hydrocarbon group having 1 to 5 carbon atoms).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a photocurable artificial nail composition that suppresses thermal pain during curing, suppresses yellowing, and has color stability. [Background technology]

[0002] Among artificial nails such as nail polish, gel nails, and acrylic nails, gel nails are widely used due to their good operability, long-term retention on natural or artificial nails, and low odor. Gel nails are photocurable artificial nail compositions that are applied to and coated on nails using a brush or the like and then cured by exposure to ultraviolet or visible light.

[0003] While gel nails require long-term physical strength and ease of use, there is also a need to shorten the light exposure time, and recently there has been a shift from light exposure devices that use low-intensity fluorescent tube lamps to high-intensity visible light LED lights.When high-intensity visible light LED lights are used as light exposure devices for gel nails, the curing time of the gel nail is shortened, shortening the treatment time, but there is an issue of heat pain felt by the patient due to the curing heat (polymerization heat) generated during light curing.

[0004] Patent Document 1 describes that a photocurable artificial nail composition containing a urethane (meth)acrylate oligomer, a polyfunctional thiol compound, a radical polymerizable compound, a photopolymerization initiator, and a chain transfer agent can suppress thermal pain during curing.

[0005] Patent Document 2 describes that the temperature rise during curing can be adjusted by using a photocurable artificial nail composition that includes a (meth)alkyl ester having a linear or branched alkyl group with 8 to 30 carbon atoms, a radically polymerizable component including a compound having at least one radically polymerizable unsaturated double bond in the molecule, and a polymerization initiator.

[0006] However, when applying a large amount of gel nail polish or creating three-dimensional art, the coating becomes thick and the patient is likely to feel heat pain, so there is still room for improvement in the conventional technology. Additionally, while gel nails are required to have an aesthetic appearance, yellowing due to the photopolymerization initiator during curing has been an issue. Another issue is that some gels have a pale yellow color, which can lead to a poor aesthetic appearance of the gel itself before curing. Conventionally, as shown in Patent Document 3, yellowing (including coloring the gel yellow before curing) has been suppressed by incorporating a certain amount of a purple-blue pigment, which is a complementary color of yellow. However, this has not yet provided a fundamental solution to the problem of yellowing. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2019-6689 [Patent Document 2] Japanese Patent Application Publication No. 2023-170592 [Patent Document 3] Japanese Patent Publication No. 2022-56207 Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide a photocurable artificial nail composition that suppresses heat pain during curing, suppresses yellowing (including those that are colored yellow before curing), and has color stability. [Means for solving the problem]

[0009] Means for solving the above problems include the following aspects. <1> A photocurable artificial nail composition comprising a photopolymerization initiator and a polymerizable compound, The photopolymerization initiator includes a compound represented by the following general formula (1), provided that it does not include an α-hydroxyalkylphenone-based photopolymerization initiator: The photocurable artificial nail composition does not contain a peroxide-based thermal polymerization initiator. [ka] (In the above general formula (1), R represents a hydrocarbon group having 1 to 5 carbon atoms.) <2> The photopolymerization initiator contains only the compound represented by the general formula (1). <1> 1. The photocurable artificial nail composition according to claim 1. <3> The photopolymerization initiator further includes 2,4,6-trimethylbenzoyldiphenylphosphine oxide and / or bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide. <1> The photocurable artificial nail composition according to claim 1. <4> The polymerizable compound includes at least one selected from the group consisting of an oligomer and a polymerizable monomer. <1> ~ <3> 10. The photocurable artificial nail composition according to claim 1, wherein <5> the polymerizable compound contains an oligomer and a polymerizable monomer; <1> ~ <3> 10. The photocurable artificial nail composition according to claim 1, wherein <6> The oligomer includes a urethane di(meth)acrylate oligomer. <4> or <5> The photocurable artificial nail composition according to claim 1. <7> Contains 0.1 to 10 mass % of the compound represented by general formula (1), <1> ~ <6> 10. The photocurable artificial nail composition according to claim 1, wherein <8> The polymerizable compound is contained in an amount of 20% by mass or more. <1> ~ <7> 10. The photocurable artificial nail composition according to claim 1, wherein <9> the content of the oligomer is 50 to 750 parts by mass per 100 parts by mass of the polymerizable monomer; <5> ~ <8> 10. The photocurable artificial nail composition according to claim 1, wherein <10> Viscosity is 1 to 2,000,000 mPa·s, <1> ~ <9> 10. The photocurable artificial nail composition according to claim 1, wherein <11> <1> ~ <10> An artificial nail obtained from the photocurable artificial nail composition according to any one of the preceding items. <12> <1> ~ <10> 1. A method for producing an artificial nail, comprising the steps of applying the photocurable artificial nail composition according to any one of claims 1 to 9 onto a nail or a substrate and curing the composition. <13> A method for forming an artificial nail, comprising applying a photocurable artificial nail composition containing a photopolymerization initiator and a polymerizable compound onto a nail or a substrate and curing the composition, The photopolymerization initiator includes a compound represented by the following general formula (1), provided that it does not include an α-hydroxyalkylphenone-based photopolymerization initiator: The method for forming an artificial nail, wherein the photocurable artificial nail composition does not contain a peroxide-based thermal polymerization initiator. [ka] (In the above general formula (1), R represents a hydrocarbon group having 1 to 5 carbon atoms.) <14> Use of a compound represented by the following general formula (1) for producing a photocurable artificial nail composition comprising a photopolymerization initiator (however, not including an α-hydroxyalkylphenone-based photopolymerization initiator) and a polymerizable compound, but not including a peroxide-based thermal polymerization initiator: [ka] (In the above general formula (1), R represents a hydrocarbon group having 1 to 5 carbon atoms.) [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a photocurable artificial nail composition that suppresses thermal pain during curing, suppresses yellowing (including those that are colored yellow before curing), and has color stability. [Brief explanation of the drawings]

[0011] [Figure 1] Photographs of test specimens for yellowness confirmation in Examples and Comparative Examples (from left: Example 6, Comparative Example 1, Comparative Example 2) DETAILED DESCRIPTION OF THE INVENTION

[0012] 1. Photocurable artificial nail composition The photocurable artificial nail composition of the present invention can provide a photocurable artificial nail composition that suppresses thermal pain during curing, suppresses yellowing (including coloring to yellow before curing), and has color stability.

[0013] The photocurable artificial nail composition of the present invention comprises a photopolymerization initiator and a polymerizable compound, and the photopolymerization initiator comprises a compound represented by the following general formula (1), with the proviso that the composition does not comprise an α-hydroxyalkylphenone-based photopolymerization initiator and does not comprise a peroxide-based thermal polymerization initiator. The photocurable artificial nail composition of the present invention will be described in detail below.

[0014] [Photopolymerization initiator] In the present invention, the photopolymerization initiator includes a compound represented by the following general formula (1). [ka]

[0015] In the general formula (1), R represents a hydrocarbon group having 1 to 5 carbon atoms. The structure of the hydrocarbon group having 1 to 5 carbon atoms is not particularly limited and may be linear, branched, or cyclic. Specific examples of R include alkyl groups such as methyl, ethyl, propyl, isopropyl, cyclopropyl, butyl, isobutyl, cyclobutyl, cyclopropylmethyl, pentyl, isopentyl, cyclopentyl, cyclopropylethyl, cyclopropyldimethyl, and cyclobutylmethyl; alkenyl groups such as vinyl, propenyl, butenyl, and pentenyl; and alkynyl groups such as ethynyl, propynyl, butynyl, and pentynyl. Among these, alkyl groups are preferred, ethyl or propyl groups are more preferred, and ethyl groups are particularly preferred.

[0016] The compound represented by the general formula (1) acts as a radical polymerization initiator. Because the photocurable artificial nail composition of the present invention contains the compound represented by the general formula (1) as a radical polymerization initiator, it is less likely to cause a sudden increase in temperature during curing, which can reduce heat pain in the patient, and it is less likely to exhibit a yellow color before curing and to turn yellow after curing.

[0017] The content of the compound represented by general formula (1) in the photocurable artificial nail composition of the present invention is not particularly limited, but is preferably in the range of 0.1 to 10% by weight, more preferably 0.8 to 8.0% by weight to improve properties such as curability, surface hardness, strength, and durability, and even more preferably 1.6 to 8.0% by weight to improve properties such as curability, surface hardness, strength, durability, and surface curability. It is even more preferably in the range of 2.0 to 6.0% by weight to improve the effects of thermal pain suppression and color stability of the present invention in addition to properties such as curability, surface hardness, strength, durability, and surface curability. It is particularly preferably in the range of 2.4 to 6.0% by weight to improve the effects of thermal pain suppression and color stability of the present invention in addition to properties such as curability, surface hardness, strength, durability, and surface curability. By keeping the content of the compound represented by general formula (1) within the above range, the effects of thermal pain suppression and color stability of the present invention can be improved.

[0018] From the viewpoint of enhancing the effects of the present invention, the photopolymerization initiator preferably contains only the compound represented by the general formula (1), but may also contain 2,4,6-trimethylbenzoyldiphenylphosphine oxide and / or bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide together with the compound represented by the general formula (1). When the photopolymerization initiator contains 2,4,6-trimethylbenzoyldiphenylphosphine oxide and / or bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, the content thereof (total content when two types are included) is, for example, 0.1 to 5 parts by mass per part by mass of the compound represented by the general formula (1). From the viewpoint of enhancing the effects of the present invention, the content is preferably 0.1 to 4 parts by mass, more preferably 0.1 to 3 parts by mass, even more preferably 0.1 to 2 parts by mass, and even more preferably 0.1 to 1 part by mass.

[0019] The photopolymerization initiator may include other photopolymerization initiators besides the above-mentioned compounds, specifically, radical polymerization initiators that generate radicals upon irradiation with energy rays such as visible light, ultraviolet light, X-rays, and electron beams, cationic polymerization initiators that generate cations, and anionic polymerization initiators that generate anions. These photopolymerization initiators may be used alone or in combination of two or more. Of these, radical polymerization initiators are preferred. Examples of radical photopolymerization initiators include benzoin ethers, benzil ketals, α-dialkoxyacetophenones, α-aminoalkylphenones, acylphosphine oxides, benzophenones, thioxanthones, and titanocenes. These radical photopolymerization initiators may be used alone or in combination of two or more.

[0020] When the photopolymerization initiator contains other photopolymerization initiators other than the compound represented by the general formula (1), the total content of the other photopolymerization initiators is preferably 80% by mass or less, more preferably 75% by mass or less, even more preferably 50% by mass or less, and particularly preferably 25% by mass or less, based on the total amount of the photopolymerization initiator. By keeping the total content of the other photopolymerization initiators within the above range, the effects of thermal pain suppression and color stability of the present invention can be further improved.

[0021] However, in the present invention, the photopolymerization initiator does not include an α-hydroxyalkylphenone-based photopolymerization initiator in order to obtain the effects of suppressing heat pain and stabilizing color tone of the present invention.

[0022] Examples of the α-hydroxyalkylphenone photopolymerization initiator include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-[4-(2-hydroxymethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-[4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl]-2-methyl-propan-1-one, 1-(4-(phenylthio)-2,2-(O-benzoyloxime))1-hydroxycyclohexyl phenyl ketone, and 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one.

[0023] Furthermore, the photocurable artificial nail composition of the present invention does not contain a peroxide-based thermal polymerization initiator in order to obtain the effects of suppressing thermal pain and stabilizing color tone of the present invention. Furthermore, the photocurable artificial nail composition of the present invention preferably does not contain a thermal polymerization initiator in order to improve the effects of suppressing thermal pain and stabilizing color tone of the present invention.

[0024] Examples of peroxide-based thermal polymerization initiators include t-butyl hydroperoxide, cumene hydroperoxide, diacetyl peroxide, didecanoyl peroxide, di-t-butyl peroxide, methyl ethyl ketone peroxide, cyclohexanone peroxide, dicumyl peroxide, di(3,5,5-trimethylhexanoyl) peroxide, 2,5-dimethylhexane-2,5-dihydroperoxide, dilauroyl peroxide, disuccinic acid peroxide, dibenzoyl peroxide, parachlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, t-butyl peroxypivalate, t-butyl peroxybenzoate, t-hexyl peroxide parethate, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate ... ester, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, n-butyl-4,4-di(t-butylperoxy)valerate, 1,1-di(t-butylperoxy)cyclohexane, 1,1-di(t-hexylperoxy)cyclohexane, 2,2-bis(4,4-di-t-butylperoxycyclohexyl)propane, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane Examples of peroxycarbonates include hexane, 2,2-bis(t-butylperoxy)butane, 2,2-bis(t-butylperoxy)octane, dicetyl peroxydicarbonate, t-hexylperoxyisopropyl monocarbonate, diisopropyl peroxydicarbonate, t-butylperoxyisopropyl carbonate, di(4-t-butylcyclohexyl)peroxydicarbonate, and di(2-ethylhexyl)peroxydicarbonate.

[0025] [Polymerizable compound] The polymerizable compound contained in the photocurable artificial nail composition of the present invention is a substance that reacts with light or heat to form a polymer. The polymerizable compound imparts properties such as curability, surface hardness, strength, flexibility, durability, and removability to the photocurable artificial nail composition of the present invention. The polymerizable compound is not particularly limited as long as it is a compound (e.g., polymerizable monomer, oligomer, polymer, etc.) having at least one ethylenically unsaturated group as a polymerizable functional group, and known polymerizable compounds can be used. Specific examples of ethylenically unsaturated groups include, but are not limited to, (meth)acryloyl groups, (meth)acryloyloxy groups, (meth)acrylamide groups, vinyl groups, vinyl ether groups, methyl vinyl ether groups, allyl groups, allyl ether groups, and maleimide groups. The ethylenically unsaturated group may be one type or two or more types. Among these, at least one type selected from the group consisting of (meth)acryloyl groups and (meth)acryloyloxy groups is preferred from the viewpoints of curability, surface hardness, and durability.

[0026] In this specification, the term (meth)acryloyl includes both acryloyl and methacryloyl, the term (meth)acrylate includes both acrylate and methacrylate, the term (meth)acryloyloxy includes both acryloyloxy and methacryloyloxy, and the term (meth)acrylamide includes both acrylamide and methacrylamide.

[0027] Examples of polymerizable compounds having one ethylenically unsaturated group per molecule include methacrylic acid, acrylic acid, urethane (meth)acrylate, methoxyethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, phenoxyethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 2-(meth)acryloyloxyethyl succinate, 2-(meth)acryloyloxyethyl phthalate, 2-(meth)acryloyloxypropyl hexaphthalate, stearyl (meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, 3-chloro-2-hydroxypropyl Examples of polymerizable monomers include, but are not limited to, polymerizable monomers such as methylol (meth)acrylamide, dimethyl (meth)acrylamide, (meth)acryloylmorpholine, and vinyl chloride; oligomers of the above polymerizable monomers; and polymers of the above polymerizable monomers. The oligomers and polymers may contain one or more of the above-listed polymerizable monomers.

[0028] In this specification, the term "oligomer" means a polymer formed by polymerizing two to several tens of polymerizable monomers, and the term "polymer" means a polymer other than an oligomer formed by polymerizing several tens or more of polymerizable monomers.

[0029] Examples of polymerizable compounds having two ethylenically unsaturated groups in one molecule include urethane di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 2-methyl-1,8-octanediol di(meth)acrylate, glycerin di(meth)acrylate, ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, and propylene glycol di(meth)acrylate. Examples of polymerizable monomers include, but are not limited to, polymerizable monomers such as bisphenol A di(meth)acrylate, polypropylene glycol di(meth)acrylate, ethoxylated polypropylene glycol di(meth)acrylate, ethoxylated propylene glycol di(meth)acrylate, ethoxylated bisphenol A di(meth)acrylate, propoxylated bisphenol A di(meth)acrylate, propoxylated ethoxylated bisphenol A di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, and bis[2-(methacryloyloxy)ethyl]phosphate; oligomers of the above polymerizable monomers; and polymers of the above polymerizable monomers. The oligomers and polymers may contain one or more of the above-exemplified polymerizable monomers.

[0030] Examples of the polymerizable compound having three or more ethylenically unsaturated groups in one molecule include urethane tri(meth)acrylate, urethane tetra(meth)acrylate, urethane penta(meth)acrylate, urethane hexa(meth)acrylate, trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, ethoxylated glycerin tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, propoxylated pentaerythritol tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, dipentaerythritol Examples of polymerizable monomers include, but are not limited to, polymerizable monomers such as thritol hexa(meth)acrylate, ethoxylated isocyanuric acid tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, caprolactone-modified pentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and caprolactone-modified pentaerythritol hexa(meth)acrylate; oligomers of the above polymerizable monomers; and polymers of the above polymerizable monomers. The oligomers and polymers may contain one or more of the above-exemplified polymerizable monomers.

[0031] The molecular weight of the polymerizable monomer is not particularly limited, but is preferably less than 1,000. The weight-average molecular weight (Mw) of the oligomer is also not particularly limited, but is, for example, 200 to 100,000, preferably 200 to 50,000, more preferably 300 to 30,000, and particularly preferably 700 to 10,000. Within this range, properties such as curability, surface hardness, strength, flexibility, durability, and removability can be improved. In this specification, the weight-average molecular weight (Mw) is a value measured by gel permeation chromatography (GPC) using polystyrene as a standard substance.

[0032] The polymerizable monomer is preferably liquid and has fluidity at 23° C. Specifically, the polymerizable monomer is preferably liquid at 23° C. and a shear rate of 10 s as measured using a rheometer, which is a dynamic viscoelasticity measuring device. -1 The viscosity at 23°C is preferably 20,000 mPa·s or less, more preferably 10,000 mPa·s or less, even more preferably 5,000 mPa·s or less, and particularly preferably 1,000 mPa·s or less. The oligomer may or may not have fluidity in an atmosphere at 23°C. Specifically, the oligomer has a viscosity at 23°C, a shear rate of 10 s, as measured using a rheometer, which is a dynamic viscoelasticity measuring device. -1 The viscosity at 23°C is preferably 9,000 mPa·s or more, more preferably 9,000 to 3,000,000 mPa·s, still more preferably 9,000 to 2,500,000 mPa·s, and particularly preferably 9,000 to 2,200,000 mPa·s. The polymer may or may not have fluidity in an atmosphere at 23°C.

[0033] Two or more polymerizable compounds may be selected to form a photocurable artificial nail composition. Among the above-listed compounds, it is preferable to use at least one selected from the group consisting of methacrylic acid, acrylic acid, urethane (meth)acrylate, urethane di(meth)acrylate, urethane tri(meth)acrylate, urethane tetra(meth)acrylate, urethane penta(meth)acrylate, urethane hexa(meth)acrylate, isobornyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, hydroxypropyl (meth)acrylate, triethylene glycol di(meth)acrylate, (meth)acryloylmorpholine, bis[2-(methacryloyloxy)ethyl]phosphate, trimethylolpropane tri(meth)acrylate, oligomers thereof, and polymers thereof. The oligomers and polymers may contain one or more of the above-listed polymerizable monomers as structural units. Furthermore, the polymerizable compound more preferably contains the oligomer and the polymerizable monomer, and further preferably contains at least one oligomer selected from the group consisting of urethane (meth)acrylate oligomers, urethane di(meth)acrylate oligomers, and urethane hexa(meth)acrylate oligomers, and at least one polymerizable monomer selected from the group consisting of isobornyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, hydroxypropyl (meth)acrylate, triethylene glycol di(meth)acrylate, (meth)acryloylmorpholine, and trimethylolpropane tri(meth)acrylate, and particularly preferably contains a urethane di(meth)acrylate oligomer and at least one polymerizable monomer selected from the group consisting of isobornyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, and trimethylolpropane tri(meth)acrylate. When the polymerizable compound contains the oligomer and the polymerizable monomer, it is possible to improve properties such as flexibility, durability, removability, curability, surface hardness, and strength.

[0034] Although there are no particular limitations on the content of the polymerizable compound, the content of the polymerizable compound relative to the total amount of the composition is preferably 20% by mass or more, more preferably in the range of 30 to 99.2% by mass, even more preferably in the range of 30 to 98.4% by mass, even more preferably in the range of 40 to 97.6% by mass, even more preferably in the range of 60 to 96% by mass, and particularly preferably in the range of 80 to 96% by mass. By keeping the content of the polymerizable compound within the above range, properties such as flexibility, durability, removability, curability, surface hardness, and strength can be improved.

[0035] When the polymerizable compound contains an oligomer and a polymerizable monomer, the content of the oligomer is typically about 10 to 1,000 parts by weight per 100 parts by weight of the polymerizable monomer. From the viewpoint of improving properties such as flexibility, durability, removability, curability, surface hardness, and strength, the content is preferably 50 to 750 parts by weight. From the viewpoint of achieving not only properties such as flexibility, durability, removability, curability, surface hardness, and hardness, but also the effects of thermal pain suppression and color stability of the present invention, the content is more preferably 100 to 350 parts by weight, even more preferably 150 to 300 parts by weight, and particularly preferably 150 to 250 parts by weight. Furthermore, when the photocurable artificial nail composition contains a polymerizable curing accelerator, as described below, the preferred content of the oligomer is calculated as the content relative to the total content of the polymerizable monomer and the curing accelerator. Thermal pain due to curing heat tends to be more pronounced with thicker coating films and higher ethylenically unsaturated group equivalents. When the content of oligomer relative to the total amount of polymerizable compounds is high, the viscosity of the photocurable artificial nail composition increases and the coating film becomes thicker, but the ethylenically unsaturated group equivalent decreases. On the other hand, when the content of polymerizable monomer relative to the total amount of polymerizable compounds is high, the viscosity of the photocurable artificial nail composition decreases and the coating film becomes thinner, but the ethylenically unsaturated group equivalent increases. By setting the content of oligomer per 100 parts by mass of polymerizable monomer within the above range, the thermal pain suppression effect of the present invention can be further enhanced.

[0036] [Other ingredients] The photocurable artificial nail composition of the present invention may contain other components in addition to the photopolymerization initiator and the polymerizable compound, provided that the effects of the present invention are not impaired. Examples of such other components include solvents, adjuvants, additives, colorants, leveling agents, plasticizers, antioxidants, thermal polymerization initiators (other than peroxide-based thermal polymerization initiators) that initiate polymerization reactions when heated to a certain temperature or higher, chemical polymerization initiators that initiate polymerization reactions by mixing specific substances together, polymerization accelerators, polymerization inhibitors, coalescing agents, preservatives, waxes, thickeners, fragrances, UV filters, diffusing agents, antifoaming agents, dispersants, fillers, surfactants, pigments, dyes, excipients, ion-releasing agents, and silane coupling agents, all of which are commonly used in photocurable artificial nail compositions. These may be used alone or in combination.

[0037] As the polymerization accelerator, a polyfunctional thiol compound having two or more thiol groups in one molecule can be used. By using a polyfunctional thiol compound, the curing reaction proceeds without being inhibited by oxygen. Specific examples of polyfunctional thiol compounds include 1,2-ethanedithiol, 1,2-propanedithiol, 1,3-propanedithiol, 1,3-butanedithiol, 2,3-butanedithiol, 1,5-pentanedithiol, 1,6-hexanedithiol, 1,8-octanedithiol, 1,9-nonanedithiol, 1,10-decanedithiol, 1,2-benzenedithiol, 1,3-benzenedithiol, 1,4-benzenedithiol, and 3,6-dichloro-1,2-benzenedithiol. ethanol, toluene-3,4-dithiol, 1,5-naphthalenedithiol, ethylene glycol bis(thioglycolate), ethylene glycol bis(3-mercaptopropionate), 1,4-butanediol bisthioglycolate, tetraethylene glycol bis(3-mercaptopropionate), trimethylolpropane tris(thioglycolate), trimethylolpropane tris(3-mercaptopropionate), trimethylolpropane tris(3-mercaptobutyrate), tris[( 3-mercaptopropionyloxy)-ethyl]isocyanurate, pentaerythritol tetrakis(thioglycolate), pentaerythritol tetrakis(3-mercaptopropionate), dipentaerythritol hexakis(3-mercaptopropionate), 1,4-bis(3-mercaptobutyryloxy)butane, pentaerythritol tetrakis(3-mercaptobutyrate), pentaerythritol tetrakis(3-mercaptobutyrate), 1,3,5-tris(3-mercaptobutyrate) (peroxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, dimercaptodiethyl sulfide, 1,8-dimercapto-3,6-dithiaoctane, 1,2-bis[(2-mercaptoethyl)thio]-3-mercaptopropane, tetrakis(7-mercapto-2,5-dithiaheptyl)methane, trithiocyanuric acid, 1,2-benzenedimethane, thiol, 4,4'-thiobisbenzenethiol, 2-di-n-butylamino-4,6-dimercapto-s-triazine, 2,5-Dimercapto-1,3,4-thiadiazole, 1,8-dimercapto-3,6-dioxaoctane, 1,5-dimercapto-3-thiapentane, Trimercaptopropionic acid tris(2-hydroxyethyl) isocyanurate, 1,4-dimethylmercaptobenzene, 2,4,6-trimercapto-s-triazine, 2-(N,N-dibutylamino)-4,6-dimercapto-s-triazine Triazine, bis(4-(2-mercaptopropoxy)phenyl)methane, 1,1-bis(4-(2-mercaptopropoxy)phenyl)ethane, 2,2-bis(4-(2-mercaptopropoxy)phenyl)propane, 2,2-bis(4-(2-mercaptopropoxy)phenyl)butane, 1,1-bis(4-(2-mercaptopropoxy)phenyl)isobutane, 2,2-bis(4-( Examples of the alkyl vinyl ether adducts include, but are not limited to, 2-mercaptopropoxy)-3-methylphenyl)propane, 2,2-bis(4-(2-mercaptopropoxy)-5-methylphenyl)propane, bis(2-(2-mercaptopropoxy)-5-methylphenyl)methane, 2,2-bis(4-(2-mercaptopropoxy)-3-t-butylphenyl)propane, tris(4-(2-mercaptopropoxy)phenyl)methane, 1,1,1-tris(4-(2-mercaptopropoxy)phenyl)ethane, bis(4-(2-mercaptobutoxy)phenyl)methane, 2,2-bis(4-(2-mercaptobutoxy)phenyl)propane, tris(4-(2-mercaptobutoxy)phenyl)methane, 1,3,5-triazine-2,4,6-trithiol, and alkyl vinyl ether adducts thereof. These polymerization accelerators may be used alone or in combination of two or more.

[0038] As the polymerization accelerator, in addition to polyfunctional thiol compounds, tertiary amines can also be used. Specific examples of tertiary amines include N,N-dimethylaniline, N,N-diethylaniline, N,N-di-n-butylaniline, N,N-dibenzylaniline, N,N-dimethyl-p-toluidine, N,N-dimethyl-m-toluidine, N,N-diethyl-p-toluidine, p-bromo-N,N-dimethylaniline, m-chloro-N,N-dimethylaniline, p-dimethylaminobenzaldehyde, p-dimethylaminoacetophenone, p-dimethylaminobenzoic acid, p-dimethylaminobenzoic acid ethyl ester, p-dimethylaminobenzoic acid amino ester, N,N-dimethylanthranilic acid methyl ester, N,N-dihydroxybenzoic acid, N,N-dimethylbenzoic acid methyl ester ... Examples of polymerization accelerators include diethylaniline, N,N-dihydroxyethyl-p-toluidine, p-dimethylaminophenyl alcohol, p-dimethylaminostyrene, N,N-dimethyl-3,5-xylidine, 4-dimethylaminopyridine, N,N-dimethyl-α-naphthylamine, N,N-dimethyl-β-naphthylamine, tributylamine, tripropylamine, triethylamine, N-methyldiethanolamine, N-ethyldiethanolamine, N,N-dimethylhexylamine, N,N-dimethyldodecylamine, N,N-dimethylstearylamine, N,N-dimethylaminoethyl methacrylate, N,N-diethylaminoethyl methacrylate, and 2,2'-(n-butylimino)diethanol. However, these are not limited to these. These polymerization accelerators may be used alone or in combination of two or more.

[0039] Some polymerization accelerators undergo a polymerization reaction with a polymerizable compound. Such polymerization accelerators are considered to be polymerizable compounds even if they do not have an ethylenically unsaturated group in their structure. Therefore, when calculating the preferred content of the oligomer in the case where the polymerizable compound contains an oligomer and a polymerizable monomer, 100 parts by weight of the polymerizable monomer means the total amount of the polymerizable monomer and the polymerizable polymerization accelerator, and the calculation is based on this.

[0040] When a polymerization accelerator is included, its content is not particularly limited, but is preferably 4% by mass or more, more preferably 6% by mass or more, even more preferably 11% by mass or more, and particularly preferably 15% by mass or more, relative to the total amount of the composition. On the other hand, the upper limit of the content is also not particularly limited, but is preferably 80% by mass or less, more preferably 70% by mass or less, even more preferably 60% by mass or less, and particularly preferably 30% by mass or less. By keeping the content of the polymerization accelerator within the above range, properties such as flexibility, durability, removability, curability, surface hardness, and strength can be improved, and good surface curability can be achieved without polymerization inhibition by oxygen.

[0041] [Method of use, characteristics, form, etc. of the photocurable artificial nail composition] The photocurable artificial nail composition of the present invention can be applied to substrates such as, but not limited to, natural nails, nails on which a coating film of the artificial nail composition has been formed, artificial resin tips, resin films, and resin sheets. Application methods include, but are not limited to, methods using a brush, sponge, spray, inkjet, air knife, and roll.

[0042] Although there is no particular limitation on the viscosity of the photocurable artificial nail composition of the present invention, from the viewpoint of ease of use, it is preferable that the composition has fluidity at 23°C. Specifically, the viscosity of the photocurable artificial nail composition is preferably at 23°C and a shear rate of 10 s as measured using a rheometer, which is a dynamic viscoelasticity measuring device. -1The viscosity at 2000,000 mPa·s or less is preferably 2,000,000 mPa·s or less, more preferably 1,000,000 mPa·s or less, even more preferably 500,000 mPa·s or less, still more preferably 200,000 mPa·s or less, even more preferably 100,000 mPa·s or less, and particularly preferably 50,000 mPa·s or less. On the other hand, there is no particular lower limit to the viscosity, but it is preferably 1 mPa·s or more, more preferably 500 mPa·s or more, even more preferably 1,000 mPa·s or more, and particularly preferably 5,000 mPa·s or more. Specific examples of the viscosity of the photocurable artificial nail composition of the present invention include 1,000 to 2,000,000 mPa·s, 5,000 to 2,000,000 mPa·s, 5,000 to 1,000,000 mPa·s, 5,000 to 500,000 mPa·s, and 5,000 to 200,000 mPa·s. Viscosities of less than 1 mPa·s are low, resulting in phenomena such as the applied photocurable artificial nail composition dripping from the surface, preventing the formation of a uniform coated surface, and resulting in poor operability of the photocurable artificial nail composition. The thermal pain caused by curing heat tends to be more pronounced the thicker the coating film, and the thickness of the coating film tends to increase as the viscosity of the photocurable artificial nail composition increases. When the viscosity of the photocurable artificial nail composition is low, the coating film becomes thinner and the thermal pain is less noticeable, but this can have a negative impact on operability, such as the photocurable artificial nail composition flowing to unintended locations after application. On the other hand, when the viscosity of the photocurable artificial nail composition is high, the coating film becomes thicker and the thermal pain is more noticeable, but this can have a positive impact on operability, such as making it possible to apply three-dimensional art. By setting the viscosity of the photocurable artificial nail composition within the above range, the thermal pain-reducing effect of the present invention can be further enhanced while maintaining good operability suitable for various purposes. The viscosity of the photocurable artificial nail composition of the present invention can be changed by appropriately adjusting the type and content of the polymerizable compound.

[0043] The form of the photocurable artificial nail composition of the present invention is not particularly limited and can be, for example, nail polish, gel nail, or acrylic nail. Nail polish is a nail coating also known as nail lacquer, nail enamel, or nail polish, and is a composition that forms a coating film with an excellent aesthetic appearance by drying the solvent contained therein. Gel nails are materials containing a resin component that cures under ultraviolet or visible light. They are compositions that form an excellent coating film with an excellent aesthetic appearance when applied to natural or artificial nails and then cured by irradiation with ultraviolet or visible light. Acrylic nails are powder-liquid materials containing polymer beads and polymerizable monomers. After mixing the powder and liquid, the polymerization of the polymerizable monomer is initiated by the polymerization initiator contained in the polymer beads, and the composition hardens. Acrylic nails are characterized by the ability to be applied and built up, and are often used primarily for nail lengthening. Among these, the photocurable artificial nail composition of the present invention is preferably provided in the form of gel nails. By forming it into a gel nail form, it is possible to provide a photocurable artificial nail composition that reduces heat pain during curing, suppresses yellowing (including those that are colored yellow before curing), and has color stability.

[0044] Gel nails generally have a coating film formed by laminating a base layer, a color layer, and a top coat layer in this order on a natural nail or substrate. There are no particular limitations on the method of application of the photocurable artificial nail composition of the present invention, and the composition can be any of the base layer, color layer, and top coat layer. Because gel nails tend to cause thermal pain when applied directly to fingernails or toenails, the photocurable artificial nail composition of the present invention is preferably used as a base layer. Furthermore, because gel nails require curability, surface strength, and durability, the photocurable artificial nail composition of the present invention is more preferably used as a top coat layer, which requires the incorporation of a large amount of components that tend to require high curing heat or that develop a strong yellowish tint before and after curing.

[0045] Gel nails include those for hands that are applied to fingernails, those for feet that are applied to toenails, and those for animals that are applied to animal nails. There are no particular limitations on the use of the photocurable artificial nail composition of the present invention, and it can be used for any of hands, feet, animals, etc.

[0046] 2. Artificial nails and their manufacturing method The artificial nail of the present invention is obtained from the photocurable artificial nail composition of the present invention. The artificial nail of the present invention can be formed, for example, by applying the photocurable artificial nail composition of the present invention to a natural nail, a nail on which a coating film of the photocurable artificial nail composition has been formed, or a substrate such as an artificial resin tip, resin film, or resin sheet, and then curing the composition. The application method is not particularly limited, and examples thereof include application methods using a brush, sponge, spray, inkjet, air knife, and roll. The curing method is not particularly limited, and examples thereof include a method of curing by irradiation with ultraviolet or visible light, and a method of curing by heating. From the viewpoint of rapid curing, a method of curing by irradiation with ultraviolet or visible light is preferred. [Example]

[0047] Examples and comparative examples of the present invention will be specifically described below, but the present invention is not limited to these examples.

[0048] [Ingredients used in preparing the photocurable artificial nail composition] The components used in preparing the photocurable artificial nail compositions of the Examples and Comparative Examples are shown below. The weight-average molecular weight (Mw) was measured by gel permeation chromatography (GPC) using a GPC measuring device (Shimadzu Corporation, product name: Nexera GPC System) and a column (Waters Corporation, product name: Styragel HR), tetrahydrofuran as an eluent, and polystyrene as a standard.

[0049] The abbreviations shown in Tables 1 to 5 are as follows. A1: Urethane diacrylate oligomer (weight average molecular weight: 8400) A2: Urethane diacrylate oligomer (weight average molecular weight: 740) A3: Isobornyl methacrylate A4: Trimethylolpropane triacrylate A5: Acrylic acid A6: Methacrylic acid A7: Bis[2-(methacryloyloxy)ethyl]phosphate Compound 1: (2,4,6-trimethylbenzoyl)phenylethoxyphosphine oxide (a compound represented by the general formula (1) above in which R is an ethyl group) Compound 2: 2,4,6-trimethylbenzoyldiphenylphosphine oxide Compound 3: Bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide

[0050] [Preparation of Photocurable Artificial Nail Composition] Each component was calculated according to the blending ratios shown in Tables 1 to 5, and mixed under atmospheric pressure using a planetary centrifugal mixer (Thinky Corporation, product name: ARV-310P) until a uniform liquid was formed, thereby preparing the photocurable artificial nail compositions of the Examples and Comparative Examples.

[0051] The photocurable artificial nail compositions of the Examples and Comparative Examples were evaluated as follows: Unless otherwise specified, the evaluations were carried out at room temperature of 23±2°C, humidity of 50±10%, and under indoor LED lighting.

[0052] [Unpolymerized rate measurement] The photocurable artificial nail compositions of the Examples and Comparative Examples were applied to a glass plate at a thickness of 0.2 mm, weighed, and then cured by irradiating with light for 20 seconds using a commercially available gel nail light (PRESTO LED light, manufactured by Nail Labo Co., Ltd.). After removing the unpolymerized surface layer of the photocurable artificial nail composition using an ethanol-soaked wipe, the weight was measured again and the unpolymerization rate was calculated using the following formula (2). From the viewpoints of ease of use, curability, and surface hardness, the unpolymerization rate of the photocurable artificial nail composition of the present invention is preferably 15.0 wt% or less, more preferably 13.5 wt% or less, even more preferably 11.0 wt% or less, and particularly preferably 9.0 wt% or less. Unpolymerized rate (wt%)=(ab) / a×100 (2) where: a: Weight of the photocurable artificial nail composition before curing b: Weight of the photocurable artificial nail composition after removing the surface unpolymerized layer

[0053] [Curing heat measurement] 50 mg of the photocurable artificial nail compositions of the Examples and Comparative Examples were uniformly applied to a commercially available plastic plate (PRESTO Clear Palette, manufactured by Nail Labo) within a specified Φ14 mm area. A thin temperature sensor (Rika Kogyo Co., Ltd., model ST-50) connected to a portable thermometer (Rika Kogyo Co., Ltd., model DP-700) was then attached to the back of the plastic plate, and the plate was irradiated with light from a commercially available gel nail light (PRESTO LED light, manufactured by Nail Labo) for 20 seconds. The temperature change of the photocurable artificial nail composition during the curing process was recorded. The maximum temperature was recorded as the curing heat, and the time from the start of light irradiation until the maximum temperature was reached was recorded as the maximum temperature arrival time.

[0054] [Yellowness confirmation test] The photocurable artificial nail compositions of the Examples and Comparative Examples were filled into a spherical silicone mold with a diameter of 12 mm and cured by irradiating them with light for 20 seconds using a commercially available gel nail light (PRESTO LED light, manufactured by Nail Labo Co., Ltd.) to produce spherical cured products. The results were evaluated according to the following criteria before curing, immediately after curing, and one day after curing. <Evaluation criteria> 1: Strong coloring 2: Coloring is permitted but usable 3: Slight coloring is observed 4: No coloring and almost transparent 5: Transparent and uncolored

[0055] [Heat pain test] The treatment was performed by a nail technician certified by the Japan Nail Technician Association on 10 subjects according to the treatment method below, and a heat pain test was conducted. <Treatment method> Step 1: Sand the natural nail surface with a sponge file. Step 2: Wipe away oil and dust with a wipe soaked in nail cleanser. Step 3: Apply the light-curable artificial nail composition of the example or comparative example. Step 4: Irradiate with a commercially available gel nail light (PRESTO LED light, manufactured by Nail Labo) for 20 seconds to allow photopolymerization. In the above treatment process, the thermal pain felt by the subjects during photopolymerization was evaluated sensorily and rated according to the following criteria, and the average value of the evaluation scores of 10 people (rounded to the nearest whole number) was used. <Evaluation criteria> 1: Severe fever and pain 2: Slight heat and pain 3: Hardening heat is felt but no pain is associated with it 4: No curing heat is felt

[0056] [Tensile test] The photocurable artificial nail compositions of the Examples and Comparative Examples were cured by irradiating them with a commercially available gel nail light (PRESTO LED light, manufactured by Nail Lab Co., Ltd.) for 20 seconds to prepare dumbbell-shaped test specimens with a thickness of 1.9 mm, a total length of 28.6 mm, a tab-to-tab distance of 25.0 mm, a parallel portion length of 15.0 mm, a shoulder radius of 7.0 mm, and a parallel portion width of 2.0 mm. These were used as test specimens for measuring tensile strength. After leaving the specimens to stand overnight, the tensile strength and breaking strain were measured using an Instron universal testing machine (manufactured by Instron, model: Instron 5943) at a crosshead speed of 10 mm / min.

[0057] [Viscosity measurement] The viscosity of the photocurable artificial nail compositions of the Examples and Comparative Examples was measured using a rheometer (manufactured by Anton Paar, model: Physica MCR 301), a dynamic viscoelasticity measuring device, under the following measurement conditions: shear rate 10 s -1 The measured value at this point was taken as the viscosity. (Measurement conditions) Measurement jig: Parallel plate PP20 Shear rate: 0.1 to 100 s -1

[0058] [Table 1]

[0059] [Table 2]

[0060] [Table 3]

[0061] [Table 4]

[0062] [Table 5] [Industrial Applicability]

[0063] According to the present invention, it is possible to provide a photocurable artificial nail composition that suppresses thermal pain during curing, suppresses yellowing (including those that are colored yellow before curing), and has color stability.

Claims

1. A photocurable artificial nail composition comprising a photopolymerization initiator and a polymerizable compound, The photopolymerization initiator includes a compound represented by the following general formula (1), provided that it does not include an α-hydroxyalkylphenone-based photopolymerization initiator: The photocurable artificial nail composition does not contain a peroxide-based thermal polymerization initiator. 【Chemical 1】 (In the above general formula (1), R represents a hydrocarbon group having 1 to 5 carbon atoms.)

2. The photocurable artificial nail composition according to claim 1 , wherein the photopolymerization initiator contains only the compound represented by general formula (1).

3. 2. The photocurable artificial nail composition according to claim 1, wherein the photopolymerization initiator further comprises 2,4,6-trimethylbenzoyldiphenylphosphine oxide and / or bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

4. 2. The photocurable artificial nail composition according to claim 1, wherein the polymerizable compound comprises at least one selected from the group consisting of an oligomer and a polymerizable monomer.

5. The photocurable artificial nail composition according to claim 1 , wherein the polymerizable compound comprises an oligomer and a polymerizable monomer.

6. The photocurable artificial nail composition according to claim 4 or 5, wherein the oligomer comprises a urethane di(meth)acrylate oligomer.

7. 2. The photocurable artificial nail composition according to claim 1, comprising 0.1 to 10% by mass of the compound represented by general formula (1).

8. The photocurable artificial nail composition according to claim 1 , comprising 20% ​​by mass or more of the polymerizable compound.

9. 6. The photocurable artificial nail composition according to claim 5, wherein the content of the oligomer is 50 to 750 parts by mass per 100 parts by mass of the polymerizable monomer.

10. 2. The photocurable artificial nail composition according to claim 1, which has a viscosity of 1 to 2,000,000 mPa·s.

11. An artificial nail obtained from the photocurable artificial nail composition according to claim 1.

12. A method for producing an artificial nail, comprising the steps of applying the photocurable artificial nail composition according to claim 1 onto a nail or a substrate and curing the composition.

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