JP2012196243A - Nail-coating ink and nail coating method - Google Patents

Abstract

An ink for nail coating that can be stably ejected in ink jet type droplet ejection and can easily apply a dense ejected material (film) to a fingernail or an artificial nail, and a specialty To provide a nail coating method capable of easily applying a dense discharge (film) to fingernails or artificial nails without being at home.
An ink for nail art according to one embodiment of the present invention includes metal particles and a polymerizable compound, and is supplied onto the surface of a nail by ink jet droplet discharge, and is cured by light irradiation. It can fix and form nail art. The contained metal particles preferably have a scale-like shape, and the constituent material is preferably at least one of aluminum, iron, nickel, and silver. In addition, the primary skin irritation index P.I. I. I. The value of is preferably 3 or less.
[Selection figure] None

Description

  The present invention relates to a nail coating ink and a nail coating method.

Nail art refers to the application of makeup by drawing letters or illustrations on the surface of the nails of the limbs.
Conventionally, when nail art is applied to a nail, a paint such as nail polish (nail color) is applied to the surface of the nail with a brush or the like. Nail polish is a paint mainly composed of nitrocellulose, and is commercialized as a nail color of various colors by adding a pigment to the paint.
When applying nail art using such a nail color, it is technically difficult to apply a nail color to one's own nails, so it is common to ask an expert such as a nail artist.

However, expert nail art is expensive and can take hours if the work is long. Moreover, when painting with a brush, it is difficult to carry out fine work, so it is not possible to draw precise illustrations.
Therefore, Patent Document 1 discloses applying nail art by an ink jet printer as a method for applying nail art more easily. With this method, even a non-expert can perform precise nail art, and the work time required for coating can be greatly shortened.

However, water-based nail art inks that can be applied to inkjet printers are known, but they must have low viscosity due to the process characteristics of being ejected from inkjet nozzles. For this reason, it takes a long time for the nail art ink after discharge to solidify, and there is a problem that the nail color discharged during that time is blurred or a sufficient thickness cannot be secured.
Such a problem is not limited to nail art inks, but can also occur in inks for forming a film on nails, such as for nail protection and medical use.

Japanese Patent Laid-Open No. 11-056452

  An object of the present invention is to provide a nail coating ink that can be stably ejected in ink-jet droplet ejection and that can easily apply a dense ejected material (film) to a fingernail or an artificial nail, Another object of the present invention is to provide a nail coating method that allows a precise discharge (coating) to be easily applied to fingernails or artificial nails without being an expert.

Such an object is achieved by the present invention described below.
The nail coating ink of the present invention contains a polymerizable compound,
It is supplied on the surface of the nail by ink jet droplet discharge and is cured by light irradiation.
Thereby, it is possible to obtain nail coating ink that can be stably ejected in ink jet type droplet ejection and that can easily apply a dense ejected material (film) to a fingernail or an artificial nail.

In the nail coating ink of the present invention, the polymerizable compound contains a primary skin irritation index P.I. I. I. The value of is preferably 3 or less.
As a result, even if the nail coating ink is directly supplied to the fingernails and a film is formed, it is difficult to adversely affect the nails and surrounding skin. For this reason, by using the nail coating ink containing such a polymerizable compound, it is possible to form a nail coating film having high biological safety.

The nail coating ink of the present invention preferably contains phenoxyethyl acrylate as the polymerizable compound.
As a result, a nail coating ink excellent in storage stability, reactivity, and quick-drying property can be obtained, and the formed film has excellent abrasion resistance. Further, when the nail coating ink contains metal particles, the dispersibility of the metal particles can be improved, and a nail coating ink capable of forming a coating film having a high aesthetics and texture peculiar to metal can be obtained.

In the nail coating ink of the present invention, as the polymerizable compound, in addition to the phenoxyethyl acrylate, 2- (2-vinyloxyethoxy) ethyl acrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, and 4 It is preferable to contain at least one selected from the group consisting of -hydroxybutyl acrylate.
As a result, a nail coating ink excellent in storage stability, reactivity, and quick-drying property can be obtained, and the formed film has excellent abrasion resistance. Further, when the nail coating ink contains metal particles, the dispersibility of the metal particles can be improved, and a nail coating ink capable of forming a coating film having a high aesthetics and texture peculiar to metal can be obtained.

In the nail coating ink of the present invention, the polymerizable compound preferably contains either dimethylol tricyclodecane diacrylate or amino acrylate.
As a result, a nail coating ink excellent in storage stability is obtained, and the formed film has excellent abrasion resistance. Further, when the nail coating ink contains metal particles, the dispersibility of the metal particles can be improved, and a nail coating ink capable of forming a coating film having a high aesthetics and texture peculiar to metal can be obtained.

The nail coating ink of the present invention preferably further contains metal particles.
Thereby, a nail coating ink capable of forming a dense film having a glossiness peculiar to metal is obtained.
In the nail coating ink of the present invention, the metal particles preferably have a scaly shape.
As a result, the metal particles have a flat surface and are likely to cause total reflection of light. For this reason, when the nail coating ink containing the metal particles having such a shape is supplied onto the surface of the nail, the main surface of the metal particles is directed in various directions, and accordingly, light from various directions is emitted. A film having light reflectivity capable of total reflection is obtained. As a result, a coating film for nail coating having a glitter characteristic of metal is obtained.

In the nail coating ink of the present invention, the constituent material of the metal particles is preferably at least one of aluminum, iron, nickel, and silver.
Thereby, a nail coating ink capable of forming a nail coating film having a particularly high metallic gloss is obtained.
In the nail coating ink of the present invention, the metal particles preferably have an average particle size of 500 nm to 2 μm.
Thereby, the glossiness and high-quality feeling of the film applied using the nail coating ink can be further improved.

The nail coating ink of the present invention preferably further contains a photopolymerization initiator.
Thereby, the polymerization reaction of the polymerizable compound can be promoted.
In the nail coating method of the present invention, the nail coating ink of the present invention is supplied to the surface of a nail of a limb or an artificial nail by ink jet droplet discharge, and then the nail coating ink is cured by light irradiation. Features.
Thereby, even if it is not an expert, a precise | minute discharge (coating) can be easily given with respect to a fingernail or an artificial nail.

Hereinafter, preferred embodiments of the present invention will be described in detail.
≪Nail coating ink≫
First, the nail coating ink of the present invention will be described.
The nail coating ink includes nail art ink for making nails, nail protection ink for protecting nails, nail medical ink for treating nails, etc. Ink for forming a film on the surface is mentioned. The coating is not limited to covering the entire surface of the nail with the coating, but includes a case where a part of the surface is covered.

Below, the ink for nail art is demonstrated typically.
The nail art ink as an embodiment of the nail coating ink of the present invention is an ink that can be applied to the surface of the nail and applied with nail art by curing.
Such an ink for nail art which is an embodiment of the present invention contains a polymerizable compound and is supplied to the surface of the nail by ink jet droplet discharge. After the supply, when the nail art ink is irradiated with light, it is cured and fixed on the surface of the nail as a coating. Therefore, it is possible to easily apply nail art without requesting a specialist such as a manicurist. Moreover, according to the ink jet type droplet discharge, the ink for nail art can be supplied at the same speed and the same fineness as ink jet printing on paper or the like, so that an extremely fine nail art can be obtained in an extremely short time. Can be applied. Furthermore, as described above, since the nail art ink of the present invention has photo-curing properties, it can be quickly fixed if it is immediately irradiated with light after being supplied to the surface of the nail. For this reason, it is possible to apply a fine and sufficient nail art in which ink bleeding is suppressed.

Hereinafter, each component of the nail art ink will be described.
(Metal particles)
The ink for nail art according to one embodiment of the present invention may contain metal particles in addition to the polymerizable compound described later.
The metal particles may be any metal-containing particles, and the constituent materials thereof include metals such as aluminum, iron, nickel, chromium, silver, gold, platinum, tin, zinc, indium, titanium, and copper. A single substance, an alloy thereof, or a mixture thereof may be used. Further, the metal particles contained in the nail art ink may be a mixture of two or more kinds of particles.

Among these, the constituent material of the metal particles is preferably at least one of aluminum, iron, nickel, and silver. Since these metal materials are excellent in light reflectivity, nail art inks containing these metal materials can perform nail art with particularly high metallic gloss.
The shape of the metal particles is not particularly limited, and examples thereof include a substantially spherical shape, a scale shape, and a needle shape. Among these, it is preferable that the metal particles contained in the nail art ink have a scaly shape. Since the metal particles having such a shape have a flat surface, they tend to cause total reflection of light. For this reason, when nail art ink containing such shaped metal particles is supplied onto the surface of the nail, the main surface of the metal particles is directed in various directions, and accordingly, light from various directions is emitted. A film having light reflectivity capable of total reflection is obtained. As a result, a nail art having a glitter characteristic of metal can be obtained.

  Further, when the metal particles having such a shape are supplied onto the surface of the nail by the ink jet method, the main surface is naturally easily arranged along the surface of the nail, depending on the supply amount. For this reason, the obtained coating film has high light reflectivity in a predetermined direction based on the metal particles arranged in a certain direction. Such a film can sufficiently reproduce the metallic luster inherent to the metal material, and the obtained nail art is particularly excellent in aesthetics and texture.

In the present invention, the scale-like shape means that the area when observed from a predetermined angle (when viewed in plan) is observed from an angle orthogonal to the observation direction, such as a flat plate shape or a curved plate shape. This refers to a shape larger than the area, in particular, the area S ₁ [μm ² ] when observed from the direction in which the projected area is maximum (when viewed in plan) and the direction orthogonal to the observation direction. The ratio (S ₁ / S ₀ ) to the area S ₀ [μm ² ] when observed from the direction in which the area is maximized is preferably 2 or more, more preferably 5 or more, and still more preferably 8 The shape is the above. In addition, for this value, for example, arbitrary 10 metal particles are evaluated, and an average value thereof is adopted.

Further, the shape of the metal particles in plan view is not particularly limited, and may be a random shape, but may be, for example, a circular shape, a polygonal shape, a star shape, a crescent shape, an annular shape, or the like.
The average particle size of the metal particles is preferably 500 nm or more and 2 μm or less, and more preferably 800 nm or more and 1.8 μm or less. As a result, the gloss and luxury of nail art applied using the nail art ink can be further improved. In the present invention, the average particle diameter means the average particle diameter based on the number, and the average diameter of perfect circles having the same area as the area S ₁ when observed from the direction in which the projected area is maximized. The value.

Further, the metal particles may be obtained by performing various surface treatments on the surfaces of the particles made of the above-described metal material as necessary. Examples of the surface treatment include treatments for bonding various coupling agents and alkoxysilane compounds.
The content of metal particles in the nail art ink is preferably 0.1% by mass or more and 5% by mass or less, and more preferably 0.5% by mass or less and 3% by mass or less. As a result, the gloss and luxury of nail art applied using the nail art ink can be further improved.

  In the photocurable ink, the metal particles have a catalytic function for promoting the curing of the ink. Since this catalytic function becomes more obvious in an oxygen-blocked environment, when the content of metal particles is excessive, the nail art ink is cured when the nail art ink is stored in an airtight container. There is a risk that. If the content of the metal particles in the nail art ink is within the above range, the nail art ink being stored is prevented from being cured without impairing the glossiness and luxury of the nail art. Can do.

  Such metal particles may be produced by any method, for example, a pulverization method for pulverizing a coarse powder obtained by pulverizing an ingot or the like to a desired particle size, a vapor phase such as vapor deposition, etc. A method of peeling and pulverizing a metal film formed on a film by a film forming method or the like (particularly a method of peeling and pulverizing in a liquid and dispersing in the liquid), a chemical granulation method, etc. Although it can manufacture by a method, in this invention, it is preferable that a metal powder is what was manufactured by various atomization methods.

  In the atomization method, molten metal (molten metal) is made to collide with a coolant such as water or gas and pulverize to manufacture. For this reason, metal particles having a uniform particle diameter can be obtained. Therefore, by using the metal particles produced by the atomizing method, a nail art ink capable of performing highly uniform nail art can be obtained. Further, in the atomization method, since coarse particles are hardly generated, the ejection stability of the nail art ink can be further improved.

Among the atomizing methods, metal particles produced by a water atomizing method using water as a coolant are preferably used. In the water atomization method, when the molten metal collides with water, the surface of the finely divided molten metal is rapidly and uniformly oxidized. As a result, a uniform oxide film is formed on the surface of the obtained metal particles, and the above-described catalytic function by the metal particles is suppressed. In addition, since the contact time with water is a moment and the formed oxide film is extremely thin, the oxide film hardly affects the glossiness of the metal particles. For this reason, the metal atom which can form the nail art excellent in the glossiness while contributing to the storage stability of the ink for nail art by the water atomization method can be obtained.
Moreover, in order to make a metal particle into a scaly shape, after manufacturing a metal particle by the atomizing method, what is necessary is just to give a rolling process. As the rolling process, for example, a process using roll rolling, a ball mill, a stamp mill, or the like is used.

(Color material)
The nail coating ink of the present invention may contain a commonly used color material. Commonly used color materials include dyes and pigments that can be dissolved or dispersed in a photopolymerizable compound. As the pigment, organic pigments, inorganic pigments and the like can be used. When the ink is a color ink containing a color material, the color can be imparted to the nail by the ink.
When no color material is contained, the nail coating ink is a so-called clear ink. In the case of clear ink, a protective layer utilizing the original color of the nail or a film that imparts a clear feeling to the nail can be formed.

(Polymerizable compound)
As described above, the nail art ink according to one embodiment of the present invention includes a polymerizable compound that is a component that is polymerized and cured by light irradiation. By including such components, the nail art formed using the nail art ink can be excellent in abrasion resistance, water resistance, solvent resistance, and the like.

The polymerizable compound is in a liquid form and preferably functions as a dispersion medium for dispersing metal particles in the nail art ink. Thereby, it is not necessary to use a dispersion medium that is separately removed (evaporated) in the nail art formation process, and a process for removing the dispersion medium becomes unnecessary, so that the nail art can be formed in a shorter time. Further, since it is not necessary to include an organic solvent that is generally used as a dispersion medium, generation of a volatile organic compound (VOC) can be prevented, which is useful from the viewpoint of environmental protection or safety. The organic solvent used as a dispersion medium is generally slightly irritating to the skin, and therefore it is desirable for the nail art ink to be supplied directly to the nail surface because it does not contain this.
Moreover, the adhesiveness of the nail art with respect to the foundation | substrate can be made excellent by including a polymeric compound. For this reason, nail art inks containing a polymerizable compound are suitable not only for fingernails, but also for nail art that is difficult to peel not only on the protective film covering the surface of the nail art but also on the surface of artificial nails made of various materials. Can be formed.

  The polymerizable compound may be any component that can be polymerized by light irradiation. For example, various monomers and various oligomers (including dimers, trimers, etc.) can be used. Nail art inks are polymerizable. The compound preferably contains at least a monomer component. Since the monomer is generally a low viscosity component compared to the oligomer component or the like, it is advantageous for making the ejection stability of the nail art ink particularly excellent.

  Specifically, those containing unsaturated carboxylic acids such as (meth) acrylic acid, itaconic acid, crotonic acid, isocrotonic acid and maleic acid are preferably used. More specifically, isobornyl acrylate, 4-hydroxybutyl acrylate, lauryl acrylate, 2-methoxyethyl acrylate, phenoxyethyl acrylate, isooctyl acrylate, stearyl acrylate, cyclohexyl acrylate, 2-ethoxyethyl acrylate, benzyl acrylate, 1H, 1H, 5H-octafluoropentyl acrylate, 1H, 1H, 5H-octafluoropentyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, isobutyl acrylate, t-butyl acrylate, tetrahydrofurfuryl acrylate, ethyl carbitol acrylate 2,2,2-trifluoroethyl acrylate, 2,2,2-trifluoroethyl meta Chlorate, 2,2,3,3-tetrafluoropropyl acrylate, methoxytriethylene glycol acrylate, methoxytriethylene glycol acrylate, PO-modified nonylphenol acrylate, EO-modified nonylphenol acrylate, EO-modified 2-ethylhexyl acrylate, EO-modified nonylphenol acrylate, phenylglycidyl Ether acrylate, phenoxydiethylene glycol acrylate, EO modified phenol acrylate, phenoxyethyl acrylate, EO modified phenol acrylate, EO modified cresol acrylate, methoxypolyethylene glycol acrylate, dipropylene glycol acrylate, dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate 2-n-butyl-2-ethyl-1,3-propanediol diacrylate, tripropylene glycol diacrylate, tetraethylene glycol diacrylate, 1,9-nonanediol diacrylate, 1,4-butanediol diacrylate Bisphenol A EO modified diacrylate, 1,6-hexanediol diacrylate, polyethylene glycol 200 diacrylate, polyethylene glycol 300 diacrylate, neopentyl glycol hydroxypiparate diacrylate, 2-ethyl-2-butyl-propanediol diacrylate , Polyethylene glycol 400 diacrylate, polyethylene glycol 600 diacrylate, polypropylene glycol diacrylate, 1,9-nonanedioldia Relate, 1,6-hexanediol diacrylate, bisphenol A EO modified diacrylate, bisphenol A EO modified diacrylate, bisphenol A EO modified diacrylate, PO modified bisphenol A diacrylate, EO modified hydrogenated bisphenol A diacrylate, dipropylene Glycol diacrylate, polypropylene glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, trimethylolpropane EO-modified triacrylate, glycerin PO-added triacrylate, trisacryloyloxyethyl phosphate, pentaerythritol tetraacrylate, PO-modified trimethylol Propane triacrylate, PO-modified trimethylol proppant Acrylate, tris (acryloxyethyl) isocyanurate, pentaerythritol triacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, acrylic acid 2- (2-vinyloxy ethoxy) ethyl and the like.

  Among them, 4-hydroxybutyl acrylate, phenoxyethyl acrylate, phenoxyethyl acrylate, dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate, tripropylene glycol diacrylate, tetraethylene glycol diacrylate, dipropylene glycol diacrylate, trimethylolpropane tri Preferred are acrylate, trimethylolpropane EO-modified triacrylate, pentaerythritol tetraacrylate, pentaerythritol triacrylate, and 2- (2-vinyloxyethoxy) ethyl acrylate.

In particular, the nail art ink preferably contains phenoxyethyl acrylate as a polymerizable compound. As a result, the storage stability of the nail art ink is excellent, the reactivity of the nail art ink after ejection by the ink jet method is particularly excellent, and the quick drying property of the nail art is particularly excellent. In addition, it is possible to make the nail art formed have particularly excellent abrasion resistance and the like.
The polymerizable compound is excellent in the dispersibility of the metal particles and the color developability when a colorant is added. For this reason, the nail art with particularly high aesthetics and texture can be obtained by uniformly dispersing the metal particles uniformly while coloring the original vivid color of the colorant.

In addition, nail art ink has a polymerizable compound, in addition to phenoxyethyl acrylate, 2- (2-vinyloxyethoxy) ethyl acrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, and 4-hydroxybutyl. It is preferable that it contains at least one selected from the group consisting of acrylates. As a result, the storage stability of the nail art ink is excellent, the reactivity of the nail art ink after ejection by the ink jet method is particularly excellent, and the quick drying property of the nail art is particularly excellent. In addition, it is possible to make the nail art formed have particularly excellent abrasion resistance and the like.
Moreover, these polymerizable compounds can particularly enhance the dispersibility of metal particles and the color developability when a colorant is added by being used together with phenoxyethyl acrylate. For this reason, the nail art with particularly high aesthetics and texture can be obtained by uniformly dispersing the metal particles uniformly while coloring the original vivid color of the colorant.

The nail art ink may contain an oligomer in addition to the monomer as the polymerizable compound. In particular, those containing polyfunctional oligomers are preferred. As a result, the storage stability of the nail art ink can be made excellent, and the rub resistance of the formed pattern can be made particularly excellent. In the present invention, among polymerizable compounds, those having a repeating structure in the molecular skeleton and having a molecular weight of 600 or more are called oligomers. As the oligomer, a urethane oligomer whose repeating structure is urethane, an epoxy oligomer whose repeating structure is epoxy, and the like are preferably used.
In addition, the nail art ink preferably contains one of dimethylol tricyclodecane diacrylate and amino acrylate as the polymerizable compound. As a result, the storage stability of the nail art ink can be further improved, and the abrasion resistance and the like of the formed nail art can be further improved.

Further, these polymerizable compounds can particularly enhance the dispersibility of the metal particles and the color developability when a colorant is added. For this reason, the nail art with particularly high aesthetics and texture can be obtained by uniformly dispersing the metal particles uniformly while coloring the original vivid color of the colorant.
The content of the polymerizable compound in the nail art ink is preferably 40% by mass or more and 80% by mass or less, and more preferably 45% by mass or more and 75% by mass or less.

  In addition, the nail art ink which is an embodiment of the present invention may be supplied directly to the surface of the fingernail, so that it is preferable to have low irritation to the nail or skin. Specifically, the polymerizable compound in the nail art ink has a skin primary irritation index P.I. which is an index of chemical skin irritation. I. I. The value of (Primary Skin Irritation Index) is preferably 3 or less, more preferably 2 or less, and even more preferably 1 or less. P. of the polymerizable compound. I. I. Is within the above range, even if the nail art ink is directly supplied to the fingernails to form the nail art, the nails and the surrounding skin are hardly adversely affected. For this reason, it becomes possible to form nail art with high biological safety by using a nail art ink containing such a polymerizable compound.

The skin primary irritation index P.I. I. I. Is evaluated by a test according to Federal Register (1972).
P.P. I. I. The polymerizable compound having a value of 3 or less is preferably 50% by mass or more, and more preferably 60% by mass or more, based on the total amount of the polymerizable compound of the nail art ink. As a result, the characteristics of the polymerizable compound of the nail art ink are low. I. I. It will be dominated by the thing, especially the negative effects on the nails and the surrounding skin will be suppressed. As a result, a nail art ink having particularly high biosafety can be obtained.

(Other ingredients)
The ink for nail art which is an embodiment of the present invention may contain components other than those described above (other components). Such components include, for example, photopolymerization initiators, colorants, slip agents (leveling agents), dispersants, polymerization accelerators, polymerization inhibitors, penetration enhancers, wetting agents (humectants), fixing agents, anti-blocking agents. Examples include glazes, preservatives, antioxidants, chelating agents, thickeners, and sensitizers (sensitizing dyes).

  The photopolymerization initiator is not particularly limited as long as it can be activated by irradiation with energy rays such as ultraviolet rays to generate active species such as radicals and cations and initiate a polymerization reaction of the polymerizable compound. . As the photopolymerization initiator, a radical photopolymerization initiator or a cationic photopolymerization initiator can be used, but it is preferable to use a radical photopolymerization initiator. When using a photopolymerization initiator, the photopolymerization initiator preferably has an absorption peak in the ultraviolet region.

Examples of the photo radical polymerization initiator include aromatic ketones, acylphosphine oxide compounds, aromatic onium salt compounds, organic peroxides, thio compounds (thioxanthone compounds, thiophenyl group-containing compounds, etc.), hexaarylbiimidazole compounds, Examples thereof include ketoxime ester compounds, borate compounds, azinium compounds, metallocene compounds, active ester compounds, compounds having a carbon halogen bond, and alkylamine compounds.
Among these, at least one selected from an acylphosphine oxide compound and a thioxanthone compound is preferable from the viewpoint of solubility in a polymerizable compound and curability, and it is more preferable to use an acylphosphine oxide compound and a thioxanthone compound in combination.

  Specific examples of the photo radical polymerization initiator include acetophenone, acetophenone benzyl ketal, 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-2-phenylacetophenone, xanthone, fluorenone, benzaldehyde, fluorene, anthraquinone, triphenylamine. , Carbazole, 3-methylacetophenone, 4-chlorobenzophenone, 4,4′-dimethoxybenzophenone, 4,4′-diaminobenzophenone, Michler's ketone, benzoin propyl ether, benzoin ethyl ether, benzyldimethyl ketal, 1- (4-isopropylphenyl) ) -2-Hydroxy-2-methylpropan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, thioxanthone, diethyl Oxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one, bis (2,4,6-trimethylbenzoyl) -phenyl Phosphine oxide, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, 2,4-diethylthioxanthone, bis- (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, etc. 1 type or 2 types or more selected from these can be used in combination.

The content of the photopolymerization initiator in the nail art ink is preferably 0.5% by mass or more and 10% by mass or less. When the content of the photopolymerization initiator is in the above range, the curing rate is sufficiently high, and the undissolved residue of the photopolymerization initiator and the color derived from the photopolymerization initiator are almost eliminated.
Further, as described above, pigments, dyes and the like are used as the colorant. The content is preferably about 0.5% by mass or more and 10% by mass or less. When the content of the colorant is within the above range, a nail art ink capable of forming a nail art excellent in quick-drying and coloring properties can be obtained.

  In addition, when supplying nail art ink to the surface of the nail by ejecting ink jet droplets, usually three types of nail art to which three kinds of colorants prepared according to the three primary colors are added respectively. Ink is prepared. In addition, if necessary, a nail art ink to which a colorant of other colors is added and a nail art ink (clear ink) not containing a colorant are also prepared. By supplying these nail art inks to a droplet discharge device (inkjet printer), a full color nail art can be formed. At this time, when the nail coating ink of the present invention containing metal particles is applied to at least one nail art ink, the obtained nail art has a glossiness peculiar to metal and has a particularly high aesthetics and texture. It will be a thing.

When the nail art ink contains a slip agent, the surface of the recorded matter becomes smooth due to the leveling action, and the abrasion resistance is improved.
Although it does not specifically limit as a slip agent, For example, silicone type surfactants, such as polyester modified silicone and polyether modified silicone, can be used, It is preferable to use polyether modified polydimethylsiloxane or polyester modified polydimethylsiloxane. .

  When the nail art ink contains a dispersant, the dispersibility of the metal particles can be made excellent, and the storage stability and ejection stability of the nail art ink can be made particularly excellent. The dispersant is not particularly limited, and examples thereof include polyoxyalkylene polyalkylene polyamines, vinyl polymers and copolymers, acrylic polymers and copolymers, polyesters, polyamides, polyimides, polyurethanes, amino polymers, silicon-containing polymers, and sulfur-containing polymers. , Fluorine-containing polymers, epoxy resins and the like.

When the nail art ink contains a polymerization inhibitor, the nail art ink being stored exhibits an inhibitory effect on the polymerization reaction of the polymerizable compound, and the storage stability can be improved.
The polymerization inhibitor is not particularly limited, for example, phenol-based polymerization inhibitors such as p-hydroquinone and p-methoxyphenol, quinone-based compounds such as p-benzoquinone and 2,5-di-tert-butylbenzoquinone. A polymerization inhibitor or the like can be used.
The content of the polymerization inhibitor in the nail art ink is preferably 0.05% by mass or more and 1% by mass or less, and more preferably 0.1% by mass or more and 0.5% by mass or less. When the content of the polymerization inhibitor is within the above range, the polymerization reaction during storage can be reliably suppressed, while the curing rate when cured after printing can be prevented from being significantly reduced.

Note that oxygen is often required in order for the polymerization inhibitor to exert a polymerization inhibition effect. Therefore, when the nail art ink containing the polymerization inhibitor is stored in a state avoiding contact with air, the polymerization inhibiting action is not exhibited, and the nail art ink is cured during storage. On the other hand, by dissolving oxygen at a concentration described later in the nail art ink containing a polymerization inhibitor, not only the action of suppressing the catalytic function by the metal particles but also the polymerization inhibition action by the polymerization inhibitor is exhibited over a long period of time. The nail art ink that has been subjected to deaeration treatment can be stored particularly stably in an airtight container.
As described above, the nail coating ink of the present invention preferably does not contain an organic solvent that is removed (evaporated) in the process of forming the nail coating film. Thereby, generation | occurrence | production of the problem of a volatile organic compound (VOC) can be prevented effectively.

The viscosity at room temperature (20 ° C.) of the nail coating ink of the present invention is preferably 20 mPa · s or less, more preferably 3 mPa · s or more and 15 mPa · s or less. Thereby, the droplet discharge by an inkjet method can be performed suitably. The viscosity is a value measured using a rheometer MCR300 manufactured by DKSH Japan.
The nail coating ink of the present invention preferably has dissolved oxygen. Thereby, even when the nail coating ink is stored in the airtight container, it is possible to prevent the ink from being cured and becoming unsuitable for droplet discharge. This is because when the nail coating ink contains metal particles, the metal particles function as a catalyst for promoting the polymerization reaction of the polymerizable compound. This is because the effect of inhibiting the catalytic function (polymerization inhibition effect) is brought about. Therefore, when oxygen is dissolved in the nail coating ink, the catalytic function of the metal particles is suppressed, and the curing of the nail coating ink during storage can be suppressed. It can be suitably performed.

  The dissolved oxygen concentration in the nail coating ink is preferably from 0.1 ppm to 25 ppm, more preferably from 1 ppm to 20 ppm, and even more preferably from 3 ppm to 15 ppm at 25 ° C. By setting the dissolved oxygen concentration in the above range, the storage stability and ejection stability of the nail coating ink can be highly compatible. That is, if the dissolved oxygen concentration is below the lower limit, the effect of inhibiting the polymerization by oxygen becomes insufficient, and the viscosity of the nail coating ink during storage may increase. On the other hand, when the dissolved oxygen concentration exceeds the upper limit, dissolved oxygen becomes too much and bubbles are likely to be generated, and the discharge stability may be lowered.

For the measurement of the dissolved oxygen concentration, for example, a measurement method such as an iodine titration method, a modified mirror method, or a diaphragm electrode method can be used. In particular, a dissolved oxygen meter (for example, DOA-32A manufactured by Toa DKK Co., Ltd.) can be measured relatively easily.
The dissolved oxygen concentration of the nail coating ink of the present invention is preferably 1% or more and 70% or less of the saturated dissolved oxygen concentration, more preferably 5% or more and 65% or less, and more preferably 10% or more and 60%. More preferably, it is as follows. Thereby, generation | occurrence | production of a bubble can be suppressed reliably, ensuring the polymerization prohibition effect by oxygen sufficiently. As a result, the storage stability and ejection stability of the nail coating ink can be made highly compatible.

In order to set the dissolved oxygen concentration of the nail coating ink within a predetermined range, the following method may be used.
First, when the dissolved oxygen concentration of the nail coating ink is lowered, for example, various deaeration processes are performed on the nail coating ink to discharge the dissolved oxygen out of the ink. In the deaeration process, one or more of various deaeration processes such as an ultrasonic deaeration process, a reduced pressure deaeration process, and a centrifugal deaeration process can be used in combination. In some cases, the deaeration process is performed while heating the nail coating ink. As a result, oxygen dissolved in the nail coating ink can be taken out as bubbles, and the dissolved oxygen concentration can be reliably lowered.

  On the other hand, when increasing the dissolved oxygen concentration of the nail coating ink, for example, oxygen-containing gas is bubbled in the nail coating ink. Thereby, oxygen can be reliably dissolved in the nail coating ink. Further, when bubbling, the nail coating ink is once cooled, sealed in an airtight container, and then returned to room temperature, so that more oxygen can be dissolved.

≪Nail coating method≫
Next, the nail coating method of the present invention will be described.
The nail coating method is a method of forming nail art, a protective film, a medical film, or the like on the surface of a fingernail or an artificial nail. Hereinafter, a method for applying nail art will be described as a representative.
In this nail art method, the nail art ink as described above is supplied onto the surface of a fingernail or artificial nail, and then the supplied nail art ink is fixed by irradiating light. How to get. By such a method, even if it is not an expert like a manicurist, precise nail art corresponding to a complicated design can be easily applied.

Hereinafter, this nail art method will be described in detail.
First, a base film (undercoat) is formed on the surface of a fingernail or an artificial nail (hereinafter simply referred to as “nail”). This base film is provided as necessary and can be omitted.
The constituent material of the base film may be any material as long as it has adhesion between the nail and the nail art, and examples thereof include hydrophilic resins such as polyvinyl alcohol, polyvinyl pyrrolidone, and methyl parahydroxybenzoate. When these resins are used, a liquid material is prepared by diluting with a solvent as required, and this is applied by various application methods, and then solidified to obtain a base film. As the coating method, for example, a spray method, a dipping method, a brush coating method, or the like is used.

Further, those obtained by excluding metal particles from the nail art ink described above are also preferably used. By using this ink, the ink for the base film can be supplied onto the surface of the nail using the droplet discharge device, as in the case of the nail art ink described later. As a result, a base film having a uniform thickness can be easily formed in a short time.
Note that the base film preferably has a color with higher brightness than the color of the nail as the base. Thereby, the coloring property and glossiness of the nail art layered on the base film can be enhanced, and the aesthetics can be improved. In order to increase the brightness of the base film, a colorant having a high brightness such as white may be added to the base film.

  Next, nail art ink is supplied onto the base film. The supply of the nail art ink can be performed using a known ink jet type droplet discharge device (ink jet printer). At this time, a full-color pattern can be drawn on the base film by supplying nail art ink exhibiting colors corresponding to the three primary colors as described above to the droplet discharge device.

Next, light is applied to the supplied nail art ink. As a result, the nail art ink is cured and fixed as a coating on the underlying film. As a result, a nail art having a pattern formed by the droplet discharge device is formed.
The light to be irradiated is not particularly limited as long as it is light having an energy capable of causing a polymerization reaction in the polymerizable compound. For example, ultraviolet light is preferably used. Further, the wavelength of light is preferably about 200 nm to 450 nm, and more preferably about 350 nm to 450 nm. When the wavelength of the light is in the above range, sufficient biosafety can be ensured while preventing the curing time of the nail art ink from being significantly increased.

The irradiation intensity at the irradiated portion is preferably at 10 mW / cm ² or more 2000 mW / cm ² or less, more preferably 20 mW / cm ² or more 1500 mW / cm ² or less. If the irradiation intensity is within the above range, the nail art ink can be cured uniformly and surely without unevenness. The light irradiation is usually started immediately after the ejection of the nail art ink. At that time, by reducing the irradiation intensity within the above range, the irradiation time can be increased accordingly. This ensures the time required for the metal particles to be oriented in the discharged nail art ink. As a result, for example, the principal surface of the scale-like metal particles is oriented along the surface of the nail, and the light reflectivity of nail art can be enhanced. The irradiation time varies depending on the irradiation intensity, but is preferably about 0.1 second to 60 seconds, more preferably about 0.5 seconds to 30 seconds.

  When the time until the nail art ink is cured is 1, the irradiation intensity is set so that the irradiation time is less than 0.5, whereby the metal particles are randomly oriented without being oriented in a certain direction. The tendency to orientate. For this reason, the obtained nail art has a characteristic of reflecting light from various directions and has a glossy feeling like a star. On the other hand, by setting the irradiation intensity so that the irradiation time becomes 0.5 or more, the metal particles tend to be oriented in a certain direction. For this reason, the obtained nail art has a characteristic of reflecting light from a certain direction with high reflectance, and has a glossy feeling like a flat mirror. As described above, according to the nail art ink which is an embodiment of the present invention, it is possible to supply a low-viscosity ink with a constant thickness. Therefore, the nail art obtained can be obtained simply by setting the irradiation time. This is useful in that it is easy to control the light reflection characteristics.

Further, the irradiation energy by light irradiation (integrated quantity of light) is preferably at 5 mJ / cm ² or more 1000 mJ / cm ² or less, more preferably 10 mJ / cm ² or more 800 mJ / cm ² or less. If the irradiation energy is within the above range, nail art having sufficient adhesion and abrasion resistance can be obtained.
As the light source, for example, a mercury lamp, a metal halide lamp, an ultraviolet light emitting diode (UV-LED), an ultraviolet laser diode (UV-LD), or the like is used. Among these, ultraviolet light emitting diodes (UV-LED) and ultraviolet laser diodes (UV-LD) are preferably used from the viewpoints of small size, long life, high efficiency, and low cost.

Next, a coating film is formed so as to cover the obtained nail art. This coating film imparts weather resistance, abrasion resistance, and the like to the nail art, but is provided as necessary and can be omitted.
As a constituent material of the coating film, any material may be used as long as it has adhesion to nail art, weather resistance, abrasion resistance, and the like. For example, cellulose acetate butyrate, toluenesulfonamide resin, acetic acid Examples thereof include sucrose-based resins such as sucrose isobutyrate and sucrose benzoate. Further, when these resins are used, a coating material is obtained by preparing a liquid material by diluting with a solvent as necessary, applying the material by various application methods, and then solidifying the material. Examples of the solvent include acetone, methyl ethyl ketone, propyl acetate, isopropyl acetate, isobutyl acetate, methanol, ethanol, n-propanol, isopropanol, n-butanol, ethyl cellosolve, ethylene glycol derivatives such as butyl cellosolve, ethyl carbitol, butyl carbonate. Examples include diethylene glycol derivatives such as bitol, and one or more of these can be used in combination.

In addition, when nail art ink containing metal particles is used for forming nail art, nail coating ink for forming a coating film is obtained by excluding metal particles from the nail art ink. Preferably used. By using this ink, the adhesion between the nail art and the coating film can be enhanced.
As described above, a precise nail art is obtained.

  In addition, according to the nail | claw coating | coated method of this invention, it can replace with the nail | claw of a finger | toe and can also perform a nail art on the surface of an artificial nail (fake nail | claw). Examples of the constituent material of the artificial nail include various thermoplastic resins such as polymethyl methacrylate, polystyrene, polycarbonate, polyvinyl chloride, polyethersulfone, polyethylene terephthalate, polyamide, and ABS resin.

The artificial nail may be hard or soft. The soft artificial nail is a so-called nail film, and is used by applying nail art to the surface and then sticking it to the fingernail. Examples of the constituent material of the nail film include polyester, nylon, polypropylene, and polyethylene.
As mentioned above, although this invention was demonstrated based on suitable embodiment, this invention is not limited to these.

Next, specific examples of the present invention will be described.
1. Nail Art Formation (Example 1)
First, aluminum powder was manufactured by the water atomization method. Next, the obtained aluminum powder was put into a planetary ball mill using zirconia beads (diameter: 5 mm), and the aluminum powder was processed into a scaly shape.

Next, a nail art ink containing the following components was prepared.
<Ink composition for nail art>
Metal particles: flat aluminum particles (average particle size D50: 0.8 μm)
Polymerizable compound: Phenoxyethyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.)
: 2- (2-vinyloxyethoxy) ethyl acrylate (manufactured by Nippon Shokubai Co., Ltd.)
: Tripropylene glycol diacrylate: Dipropylene glycol diacrylate: 4-hydroxybutyl acrylate

Photopolymerization initiator: bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide (Ciba Japan Co., Ltd., IRGACURE 819)
: 2,4,6-trimethylbenzoyldiphenylphosphine oxide (Lambson, speedcure TPO)
: 2,4 diethylthioxanthone (Lambson, speedcure DETX)
-Polymerization inhibitor: p-methoxyphenol-Leveling agent: Silicone surface conditioner (by Big Chemie Japan, UV-3500)

Next, the nail art ink was degassed and sealed in an airtight container so as not to entrain air. As a result, an ink pack was obtained.
Next, the ink pack was loaded into a droplet discharge device, and striped nail art having a line width of 100 μm and a pitch of 100 μm was drawn on the surface of a polypropylene artificial nail.
Next, ultraviolet rays having a peak wavelength of 365 nm were irradiated at an irradiation intensity of 100 mW / cm ² and an integrated light amount of 200 mJ / cm ² to cure the nail art.

(Examples 2 to 14)
Nail art was obtained in the same manner as in Example 1, except that the types and ratios of the raw materials used for preparing the nail art ink in the ink pack were changed as shown in Table 1 or Table 2, respectively.

In Tables 1 and 2, phenoxyethyl acrylate (PII: 1.7) is “PEA”, 2- (2-hydroxyethoxy) ethyl acrylate is “VEEA”, tripropylene glycol diacrylate (PII: 1). .6) “TPGDA”, dipropylene glycol diacrylate “DPGDA”, N-vinylcaprolactam “VC”, benzyl methacrylate “BM”, dimethylol tricyclodecane diacrylate “DMTCDDA”, amino acrylate “ "AA", urethane acrylate "UA", Irgacure 819 (Ciba Japan) "ic819", Speedcure TPO (ACETO) "scTPO", Speedcure DETX (Lambson) "scDETX", UV 3500 (manufactured by BYK-Chemie GmbH) to "UV3500", the p- methoxyphenol "pMP", 4-hydroxybutyl acrylate: showed (PII 3) in "HBA".
Moreover, about Example 10, it replaced with the water atomizing method and used the aluminum powder manufactured by the gas atomizing method.
In Example 14, the shape processing process of the aluminum powder by the planetary ball mill was omitted.

(Example 15)
Nail art was obtained in the same manner as in Example 1 except that the addition of metal particles was omitted and the types and ratios of the raw materials were as shown in Table 2.
(Comparative Example 1)
A nail art was obtained in the same manner as in Example 1 except that an aqueous ink containing metal particles was prepared and used as an ink for nail art. The nail art was solidified by blowing warm air at 40 ° C. for 5 minutes instead of ultraviolet irradiation.
The composition of the water-based ink is a mixture of flat aluminum particles (average particle diameter D50: 0.8 μm), 2-pyrrolidone 50 g, ethylene glycol 20 g, rosin resin 5 g, and water 400 g, and the content of the flat aluminum particles Was 2.0 mass%.
(Comparative Example 2)
A nail art was obtained in the same manner as in Comparative Example 1 except that the addition of metal particles was omitted.

2. Evaluation of nail art 2.1. Fineness Evaluation The fineness of the nail art obtained in each Example and each Comparative Example was evaluated as follows.
First, the nail art was observed with an optical microscope, the line widths at 10 locations were measured, and the average value was calculated. And it evaluated based on the following evaluation criteria.

<Fineness evaluation criteria>
A: The amount of deviation from the set value (100 μm) of the line width is less than 10 μm B: The amount of deviation from the set value of the line width (100 μm) is 10 μm or more and less than 20 μm C: The set value of the line width (100 μm) The amount of deviation from 20 μm or more and less than 30 μm D: The amount of deviation from the set value of line width (100 μm) is 30 μm or more and less than 40 μm E: The amount of deviation from the set value of line width (100 μm) is 40 μm or more F: The amount of deviation from the set value (100 μm) of the line width is 50 μm or more.

2.2. Glossiness Evaluation About the nail art obtained in each Example and each Comparative Example, the glossiness at a turning angle of 60 ° was measured using the glossiness meter (MINOLTA MULTI GLOSS 268) and evaluated according to the following criteria. In addition, it can be said that this glossiness is so excellent that the beauty as a nail art is high.

<Evaluation criteria for glossiness>
A: Glossiness of 300 or more (particularly good aesthetics)
B: Glossiness is 200 or more and less than 300 (aesthetics are slightly good)
C: Glossiness of 100 or more and less than 200 (Aesthetic feeling is slightly poor)
D: Glossiness is less than 100 (aesthetics are poor)

2.3. Stability evaluation in droplet discharge (discharge stability evaluation)
For the nail art inks obtained in each Example and each Comparative Example, the stability in droplet ejection was evaluated as follows.
First, each ink pack was heated at a temperature of 60 ° C. for 5 days.
Next, a droplet discharge device is installed in the chamber (thermal chamber), and each sample No. heated is heated. Ink packs were prepared. Then, after optimizing the driving waveform of the piezo element of the droplet discharge device, 25,000 (2 million droplets) of nail art ink liquid from the nozzle of the droplet discharge head in an environment of 25 ° C. and 55% RH. Drops were continuously discharged. Then, the average value of the deviation amounts d from the center aiming position of the center positions of the respective droplets landed was obtained, and the average value of the deviation amounts d was evaluated according to the following five-stage criteria. In addition, it can be said that generation | occurrence | production of a flight curve is prevented effectively and the discharge stability is so high that this value is small.

<Evaluation criteria for ejection stability>
A: The average value of the deviation amount d is less than 0.09 μm B: The average value of the deviation amount d is 0.09 μm or more and less than 0.15 μm C: The average value of the deviation amount d is 0.15 μm or more and 0.18 μm D: The average value of the deviation amount d is 0.18 μm or more and less than 0.22 μm. E: The average value of the deviation amount d is 0.22 μm or more. As described above, the evaluation results of 2.1 to 2.3 are obtained. Table 3 shows.

  As shown in Table 3, it was recognized that the nail art obtained in each example was a dense nail art excellent in gloss. This is because the nail art ink obtained in each example was able to be cured immediately after being discharged (excellent in quick-drying), so that the metal particles are easily arranged in a random state, As a result, it is assumed that the light reflectivity in all directions is increased and bleeding is suppressed.

Further, in the nail art obtained in Example 15, no glossiness was obtained, but no bleeding was observed.
On the other hand, in the nail art obtained in Comparative Example 1, although light reflection in a predetermined direction was recognized, light reflection in the measurement direction was low. In Comparative Examples 1 and 2, the occurrence of bleeding was observed.

  Further, the nail art inks obtained in the respective Examples and Comparative Example 2 were all excellent in ejection stability, but the nail art ink obtained in Comparative Example 1 had low ejection stability. This result is presumed to be due to the fact that the metal particles were not sufficiently dispersed in the nail art ink obtained in Comparative Example 1 and thus had an adverse effect on the ink ejection behavior and flight behavior. Is done.

Claims (11)

Containing a polymerizable compound,
An ink for nail coating, which is supplied onto the surface of a nail by ink jet droplet discharge and is cured by light irradiation.   The polymerizable compound has a skin primary irritation index P.I. I. I. The nail coating ink according to claim 1, wherein the value of is n or less.   The nail coating ink according to claim 1 or 2, comprising phenoxyethyl acrylate as the polymerizable compound.   In addition to the phenoxyethyl acrylate, the polymerizable compound is selected from the group consisting of 2- (2-vinyloxyethoxy) ethyl acrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, and 4-hydroxybutyl acrylate The nail coating ink according to claim 3, comprising at least one selected from the above.   The nail coating ink according to any one of claims 1 to 4, wherein the polymerizable compound contains one of dimethylol tricyclodecane diacrylate and amino acrylate.   The nail coating ink according to any one of claims 1 to 5, wherein the nail coating ink further contains metal particles.   The nail coating ink according to claim 6, wherein the metal particles have a scaly shape.   The nail coating ink according to claim 6 or 7, wherein a constituent material of the metal particles is at least one of aluminum, iron, nickel, and silver.   The nail coating ink according to any one of claims 6 to 8, wherein an average particle diameter of the metal particles is 500 nm or more and 2 µm or less.   The nail coating ink according to any one of claims 1 to 9, further comprising a photopolymerization initiator.   The nail coating ink according to any one of claims 1 to 10 is supplied to the surface of a nail of a limb or an artificial nail by ink jet droplet discharge, and then the nail coating ink is cured by light irradiation. A nail coating method characterized by the above.