in the present invention , a compound having at least one radical polymerizable unsaturated double bond in the molecule ( a ) can be used by selected from known monofunctional and polyfunctional polymerizable monomers . typical examples of the compound , which is preferably used , include polymerizable monomers having an acryloyl group and / or a methacryloyl group . in the present invention , both an acryloyl group - containing polymerizable monomer and a methacryloyl group - containing polymerizable monomer are comprehensively represented by ( meth ) acrylate or ( meth ) acryloyl . specific examples thereof include monofunctional monomers such as methoxyethylene glycol ( meth ) acrylate , methoxypolyethylene glycol ( meth ) acrylate , phenoxyethylene glycol ( meth ) acrylate , phenoxypolyethylene glycol ( meth ) acrylate , 2 - hydroxy - 3 - phenoxypropyl ( meth ) acrylate , 2 -( meth ) acryloyloxyethylsuccinic acid , 2 -( meth ) acryloyloxyethylphthalic acid , 2 -( meth ) acryloyloxypropylhexaphthalic acid , stearyl ( meth ) acrylate and 3 - chloro - 2 - hydroxypropyl ( meth ) acrylate ; difunctional monomers such as 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 , polyethylene glycol di ( meth ) acrylate , propylene glycol 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 and tricyclodecanedimethanol di ( meth ) acrylate ; and tri - or higher polyfunctional monomers such as 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 ( meth ) acrylate , dipentaerythritol hexa ( meth ) acrylate and ethoxylated isocyanuric acid tri ( meth ) acrylate . in addition to the above - described ( meth ) acrylate - based polymerizable monomers , other polymerizable monomers , oligomers or polymers of monomers , for example , monomers having at least one polymerizable group in the molecule may be used without any limitation according to the purposes of the artificial nail composition . these monomers may have a substituent such as an acidic group or a fluoro group in the same molecule . in the present invention , a compound having at least one radical polymerizable unsaturated double bond in the molecule ( a ) includes not only a single component , but also a mixture of polymerizable monomers . when the polymerizable monomer has very high viscosity at room temperature or is a solid , it is preferred to use as a mixture of a low - viscosity polymerizable monomer and a polymerizable monomer . not only two or more kinds , but also three or more kinds may be used in combination . furthermore , in order to improve adhesion of the artificial nail composition with a natural nail and / or an artificial nail , it is possible to include an acidic compound having at least one radical polymerizable unsaturated double bond in the molecule as a compound having at least one radical polymerizable unsaturated double bond in the molecule ( a ). specifically , the acidic compound is a compound having a carboxyl group , a sulfonic acid group or a phosphoric acid group , preferably an acidic phosphorus compound having at least one radical polymerizable unsaturated double bond in the molecule , and particularly preferably a compound having a p — oh bond . examples of the substituent include a phosphoric acid monoester group , a phosphoric acid diester group , a phosphonic acid group , a phosphonic acid monoester group , a phosphorous acid monoester group , a phosphinic acid group and a pyrophosphoric acid group . among these groups , a phosphoric acid monoester group , a phosphoric acid diester group and a phosphonic acid group are particularly preferred . in the present invention , the radical polymerization initiator ( b ) can be used in an amount within a range from 0 . 01 to 10 parts by weight , and preferably from 0 . 1 to 5 parts by weight . also , known thermopolymerization initiators and photopolymerization initiators can be used . examples of the photopolymerization initiator include benzoinethers , benzylketals , α - dialkoxyacetophenones , α - hydroxyalkylphenones , α - aminoalkylphenone , acylphosphine oxides , benzophenones , thioxanthones and titanocenes . among these , 2 - hydroxy - 2 - methylpropiophenone and acylphosphine oxides are preferred . it is also preferred to use the above - described photoinitiator in combination with the photopolymerization accelerator . in particular , when tertiary amines are used as the photopolymerization accelerator , it is more preferred to use a compound in which a nitrogen atom is directly substituted on an aromatic group . it is possible to use , as the photopolymerization accelerator , tertiary amines such as 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 - dihydroxyethylaniline , n , n - dihydroxyethyl - p - toluidine , p - dimethylaminophenyl alcohol , p - dimethylaminostyrene , n , n - dimethyl - 3 , 5 - xylidin , 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 ) dimethanol ; barbituric acids such as 5 - butylbarbituric acid and 1 - benzyl - 5 - phenylbarbituric acid , and metal salts thereof such as sodium salts and calcium salts ; and tin compounds such as dibutyl - tin - diacetate , dibutyl - tin - dimaleate , dioctyl - tin - dimaleate , dioctyl - tin - dilaurate , dibutyl - tin - dilaurate , dioctyl - tin - diperacetate , dioctyl - tin - s , s ′- bis - isooctylmercaptoacetate and tetramethyl - 1 , 3 - diacetoxydistanoxane . among these photopolymerization accelerators , at least one kind can be selected and used , and two or more kinds of them can be used in combination . the amount of the above - described initiators and accelerators can be appropriately decided . furthermore , it is effective to add , in addition to tertiary amines , oxycarboxylic acids such as citric acid , malic acid , tartaric acid , glycolic acid , gluconic acid , α - oxyisobutyric acid , 2 - hydroxypropanoic acid , 3 - hydroxypropanoic acid , 3 - hydroxybutanoic acid , 4 - hydroxybutanoic acid and dimethylolpropionic acid so as to improve photopolymerization acceleration ability . specific examples of the thermopolymerization initiator which can be preferably used include organic peroxides such as benzoyl peroxide , parachlorobenzoyl peroxide , 2 , 4 - dichlorobenzoyl peroxide , acetyl peroxide , lauroyl peroxide , tertiary butyl peroxide , cumen hydroperoxide , 2 , 5 - dimethylhexane - 2 , 5 - dihydroperoxide , methyl ethyl ketone peroxide and tertiary butylperoxybenzoate ; and azo compounds such as azobisisobutyronitrile , methyl azobisisobutyrate and azobiscyanovaleric acid . the polymerization can also be performed at normal temperature by using the above - described organic peroxide in combination with an amine compound . it is preferred to use , as the amine compound , a secondary or tertiary amine in which an amine group is bonded with an aryl group in view of curing acceleration . for example , n , n - dimethyl - p - toluidine , n , n - dimethylaniline , n , n - β - hydroxyethyl - aniline , n , n - di ( β - hydroxyethyl )- aniline , n , n - di ( β - hydroxyethyl )- p - toluidine and n - methyl - aniline , n - methyl - p - toluidine are preferred . it is also preferred to use , in addition to a combination of the organic peroxide and the amine compound , sulfinate or borate in combination . examples of sulfinates include sodium benzenesulfonate , lithium benzenesulfinate and sodium p - toluenesulfinate . examples of borates include sodium salts , lithium salts , potassium salts , magnesium salts , tetrabutylammonium salts and tetramethylammonium salts of trialkylphenylboron and trialkyl ( p - fluorophenyl ) boron ( an alkyl group is an n - butyl group , an n - octyl group , n - dodecyl group , etc .). it is also possible to use , as an organometallic polymerization initiator , organoboron compounds capable of reacting with oxygen or water to generate a radical , such as tributylborane and a partial oxide of tributylborane . in the present invention , examples of the organic and / or inorganic colorant utilizing an absorbing and / or scattering phenomenon of light ( c ) include organic colorants such as azo - based pigments , phthalocyanine - based pigments and polycyclic pigments ; and inorganic colorants , for example , typical white pigments such as titanium oxide , rutile titanium , anatase titanium , zinc oxide , aluminum oxide and zinc sulfide . it is possible to use , as the inorganic colorant , yellow iron oxide , color and / or black pigments such as ultramarine blue , blood red , carbon black and graphite in combination . titanium oxide and aluminum oxide are suited as the inorganic colorant . specific examples of the organic colorant include victoria pure blue b , α - phthalocyanine blue , β - phthalocyanine blue , γ - phthalocyanine blue , ε - phthalocyanine blue , naphthol red frr , naphthol as , naphthol red , pyrazolone red b , bona barium lake , bona calcium lake , bona strontium lake , magnesium lake , rhodamine y , thioindigo violet , naphthol red fgr , quinacridone magenta , toluidine red , parachlor red , hanza yellow g , hanza yellow gr , disazo yellow aamx , disazo yellow aaot , vulcan fast yellow 5g , arylide yellow ncg , flavanthron yellow , strontium yellow and antimony yellow . in particular , as a combination of color organic colorants , for example , pigment blue 15 : 2 ( α - phthalocyanine blue ) is suited as a blue organic colorant , pigment red 48 : 2 ( bona calcium lake ) is suited as a red organic colorant , and pigment yellow 14 ( diazo yellow aaot ) is suited as a yellow colorant . in the present invention , the inorganic colorant having at least one kind of an interference color ( d ) is a colorant capable of developing a different color due to the fact that since light travels in a wave form , the light reflected by the surface when light contacts a thin film having a thickness which is nearly equal to the wavelength of visible rays interferes with the light reflected by the inside or reflected on the back surface and thus causes amplification or cancellation . specifically , the inorganic colorant having an interference color is an inorganic colorant having an interference color in which an anatase type titanium oxide , a rutile type titanium oxide , a pseudobrookite type titanium oxide or tin oxide are uniformly coated on a base material such as a glass flake or aluminum oxide . an inorganic colorant comprising an aluminum oxide as the base material , and titanium oxide and tin oxide coated on the aluminum oxide is particularly preferred . in the present invention , a contrast ratio gives a measure of transparency . the contrast ratio is a measure of transparency and is calculated using a y value relating to brightness in a tristimulus value of a xyz color system determined by jis z8701 . specifically , a black background or a white background is contacted with a 200 μm cured artificial nail composition . standard light c is irradiated , and a y value in the reflected light is read . the contrast ratio ( c ) is determined from yb / yw where yb denotes y having a black background and yw denotes y having a white background . as the value c approaches 1 , the cured body approaches an opaque cured body , while as the value c approaches 0 , the cured body approaches a transparent cured body . the present invention will be described in detail by way of examples , but the invention is not limited to the following examples . ( a ) compound having at least one radical polymerizable unsaturated double bond in the molecule udma : dimethacryloxyethyl - 2 , 2 , 4 - trimethylhexamethylene diurethane bisgma : bisphenol a - diglycidyl methacrylate 14g : tetradecaethylene glycol dimethacrylate bismep : bis [ 2 -( methacryloxy ) ethyl ] phosphate 4aet : 4 - acryloxyethyltrimellitic acid ( c ) organic and / or inorganic colorant utilizing an absorbing and / or scattering phenomenon of light blue 5050a : fastogen blue 5050a ( manufactured by dainippon ink and chemicals , incorporated .) red 3013 : symuler red 3013 ( manufactured by dainippon ink and chemicals , incorporated .) yellow 5gf : symuler fast yellow 5gf ( manufactured by dainippon ink and chemicals , incorporated .) ( d ) inorganic colorant having at least one kind of interference color ultraviolet polymerization apparatus : akzentz uv lamp ( model uvl - 92 , manufactured by takigawa co ., ltd .) methods for preparation of materials and evaluation methods used in examples of the present invention will be described below . raw materials ( a ) and ( b ) were weighed in accordance with the formulation shown in table 1 , mixed under atmospheric pressure at 60 ° c . for 3 hours and then mixed under atmospheric pressure at 23 ° c . for 12 hours . raw materials ( c ) and ( d ), and additives were weighed and then additive raw materials were dispersed using an autorotation / revolution type mixer . after degassing under 40 to 45 torr , a high - viscosity transparent liquid was obtained . a ring type stainless steel mold having measuring 30 mm in diameter ( inner diameter ) and 200 μm in thickness was filled with the artificial nail composition . the shape was modified and the surface to be irradiated with light was shielded from air by pressure welding using glass in a vertical direction . using an ultraviolet polymerization apparatus ( akzentz uv lamp ), photopolymerization of upper and lower surfaces was performed for 3 minutes respectively to produce a disk - shaped cured body of the artificial nail composition . this resultant disk - shaped cured body was used as a disk - shaped specimen for colorimetry . colorimetry was performed in accordance with jis z8722 : 2000 . the measurement conditions are described below . a ) illuminant and color system : an auxiliary illuminant was used and an xyz color system was used . b ) the measurement was carried out by a reflection measuring method . c ) geometrical / optical conditions defined in jis z 8722 used for measurement : conditions c [ 8 / 0 ] d ) model and name of test apparatus : spectrophotometer ( model cm - 2002 , manufactured by konica minolta holdings , inc .) e ) back surface of specimen : optical trap free from transmissiveness and internal reflection was used . from the resultant xyz values , cie1976ab chroma ( may be abbreviated to c * in this example ) was obtained by a calculation formula described in jis z8729 : 2004 . the resultant cie1976ab chroma is shown in table 1 . furthermore , spectral reflectance graphs obtained under the calorimetric conditions are shown in fig1 to 15 . in the present invention , a contrast ratio gives a measure of transparency . the contrast ratio is a measure of transparency and is calculated by a y value relating to brightness in the tristimulus values of a xyz color system . specifically , a black background or a white background is contacted with a 200 μm thick cured artificial nail composition , standard light c is irradiated and the y value in reflected light is read . the contrast ratio ( c ) is determined from yb / yw where yb denotes y having a black background and yw denotes y having a white background . as the value c approaches 1 , the cured body approaches an opaque cured body , while as the value c approaches 0 , the cured body approaches a transparent cured body . the resultant contrast ratio is shown in table 1 . as is apparent from the results shown in fig8 , fig9 , fig1 and fig7 , in examples 1 to 12 , spectra of spectral reflectances each having a peak at about 450 nm were obtained and the resultant cured compositions were cured compositions each having a blue interference color . the cured compositions of examples 1 to 12 developed a violetish red and were excellent in appearance . as is apparent from the results shown in fig7 and fig8 , in comparative examples 22 to 25 , spectra of spectral reflectances each having a peak at about 450 nm were obtained and the resultant cured compositions were cured compositions each having a blue interference color . however , as is apparent from the results shown in table 1 , a contrast ratio of the cured compositions was 0 . 6 or more and an interference color giving beautiful appearance was decreased by scattering caused by the component ( c ), and the resultant cured compositions were inferior in appearance . similarly , as is apparent from the results shown in fig6 , in examples 13 to 14 , spectra of spectral reflectances each having a peak at about 450 nm were obtained and the resultant cured compositions were cured compositions each having a blue interference color . the cured compositions of examples 13 to 14 developed a violetish red and were excellent in appearance . however , as is apparent from the results shown in fig5 and fig6 , in comparative examples 26 to 29 , spectra of spectral reflectances each having a peak at about 450 nm were obtained and the resultant cured compositions were cured compositions each having a blue interference color . however , as is apparent from the results shown in table 1 , a contrast ratio of the cured compositions was 0 . 6 or more and an interference color giving beautiful appearance was decreased by scattering caused by the component ( c ), and the resultant cured compositions were inferior in appearance . the compositions of comparative examples 1 to 21 are compositions containing no component ( d ). as is apparent from the results shown in fig1 to 15 , spectral reflectances with a color tone derived from the component ( d ) were obtained . when compared with the cured compositions containing a component ( d ) of examples , as is apparent from the results shown in table 1 , the compositions showed low cie1976ab chroma at the same contrast ratio and were inferior in appearance because a vivid color was not obtained . as is apparent from the results shown in fig1 to 4 , in examples 15 to 26 , the spectra of spectral reflectances each having a peak at about 610 to 750 nm were obtained and the resultant cured compositions were cured compositions each having a red interference color . the cured compositions of examples 15 to 26 were excellent in appearance . however , in comparative examples 30 to 33 , spectra of spectral reflectances each having a broad peak at about 610 to 750 nm were obtained and the resultant cured compositions were cured compositions each having a red interference color . as is apparent from the results shown in table 1 , a contrast ratio of the cured compositions was 0 . 6 or more and an interference color giving beautiful appearance was decreased by scattering caused by the component ( c ), and the resultant cured compositions were inferior in appearance .
the present invention provides an artificial nail composition which can easily impart a special appearance to the tip of the finger , and which is an artificial nail material coated on a natural or artificial nail , and is used by coating on the surface of a natural or artificial nail followed by polymerization and , more particularly , an artificial nail composition which is vivid and has a natural color tone having a transparent sensation , that cannot be achieved by a conventionally used artificial nail composition containing an organic and / or inorganic colorant utilizing absorption and / or a scattering phenomenon of light , and imparts special appearance by an interference color .