Method of bonding or decorating artificial nail

A method of bonding an artificial nail to a nail with a photocurable cyanoacrylate adhesive or of decorating an artificial nail or a nail using the adhesive. The adhesive comprises (A) an cyanoacrylate monomer, (B) a catalyst selected from the group consisting of a metallocene compound comprising a transition metal of Group VIII of the periodic table and aromatic electron system ligands, and a mixed catalyst consisting of a combination of a cleavage-type photoinitiator and a metallocene compound comprising a transition metal of Group VIII of the periodic table and aromatic electron system ligands, an acetylacetonatoplatinum(II) complex, and a specific metal complex which releases a nucleophilic agent upon light irradiation. The curability of the adhesive of the present invention in the bonding of an artificial nail to a nail or in the bonding of a decorative article to a nail or artificial nail is improved in the case where the adhesive has flowed out of the bonding part or has been applied thickly so as to fill (build up) the recessed part of the joint, etc.

FIELD OF THE INVENTION 
.alpha.-Cyanoacrylate adhesives are used in many applications as 
cold-setting single-liquid type instantaneous adhesives, because they 
rapidly polymerize and cure by the action of a minute amount of the 
adsorption water present on adherend surfaces to extremely tenaciously 
bond the adherends to each other in a short time period. Among those 
applications are the bonding of artificial nails to nails and the bonding 
of various decorative articles to artificial nails. 
BACKGROUND OF THE INVENTION 
Various prior art techniques for the bonding of artificial nails to nails 
with an .alpha.-cyanoacrylate adhesive have been disclosed. For example, 
specific .alpha.-cyanoacrylate adhesive compositions for artificial-nail 
bonding are disclosed in JP-A-58-99908 and JP-A-58-103406. (The term 
"JP-A" as used herein means an "unexamined published Japanese patent 
application.") In JP-A-59-226077 is disclosed an .alpha.-cyanoacrylate 
adhesive composition for artificial-nail bonding which contains poly(vinyl 
acetate) having a weight-average molecular weight of 10,000 or higher. In 
JP-A-6-264034 is disclosed an .alpha.-cyanoacrylate adhesive composition 
for artificial-nail bonding which contains a halogenonitropropane. 
Further, an .alpha.-cyanoacrylate adhesive composition for artificial-nail 
bonding which contains a specific fluorinated alkyl acrylate or 
fluorinated alkyl methacrylate is disclosed in JP-A-7-70519. 
There are several methods for the attachment of an artificial nail. A 
representative method comprises bonding an artificial nail to a nail, 
subsequently filling (building up) the recessed part of the joint between 
the nail and the artificial nail with a resin, smoothing the resin surface 
with a nail file or nail polisher, and then finishing the joint and the 
artificial nail by coating a nail lacquer or a resin. If desired, a 
decorative article is bonded to the surface of the artificial nail. 
However, the .alpha.-cyanoacrylate adhesives have a drawback that the 
curing is very slow when the gap between adherends is wide, when the 
adhesive applied has overflown from the bonding part, or when the adhesive 
applied is not sandwiched between adherends as in coating. Because of 
this, the use of those .alpha.-cyanoacrylate adhesives is basically 
limited to the bonding of artificial nails to nails. 
In the case where an .alpha.-cyanoacrylate adhesive is used for filling 
(building up) the recessed part of the joint between a nail and an 
artificial nail or as a finishing coating agent, the generally employed 
method for curing the adhesive is to use a primer or a curing accelerator. 
In attaching a decorative article to an artificial nail, it is difficult 
to apply the adhesive in a controlled amount so as to prevent the adhesive 
from flowing out of the bonding part because the decorative article is 
small. In this case also, when the adhesive which has flowed out is cured, 
a primer or a curing accelerator is used. However, such methods are 
disadvantageous not only in that the steps are troublesome, but also from 
the standpoint of working environment, for example, because the odor of 
the basic compound used as the main component of the primer or curing 
accelerator and the odor of the solvent make the user unpleasant. 
There has hence been a desire for a cyanoacrylate adhesive which retains 
the excellent features of instantaneous adhesives, i.e., cold-setting and 
single-liquid type, and which is usable not only as an adhesive for 
bonding a nail to an artificial nail, but also as an improved filling 
(building up) material to be applied to the recessed part of the joint 
between the nail and the artificial nail, as a coating agent for 
finishing, or as an adhesive for bonding a decorative article to an 
artificial nail. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide a method of bonding an 
artificial nail to a nail with an adhesive or of decorating an artificial 
nail or a nail using an adhesive to overcome the above-described problems 
in the prior art. 
To accomplish the above object, the problems described above were 
eliminated by bonding an artificial nail to a nail with a photocurable 
cyanoacrylate adhesive or by bonding a decorative article to an artificial 
nail with the adhesive. 
The present inventors have found that the above object is achieved with the 
following embodiments: 
(1) A method of bonding an artificial nail to a nail with an adhesive or of 
decorating an artificial nail or a nail using an adhesive, said adhesive 
being a photocurable cyanoacrylate adhesive. 
(2) The method of bonding an artificial nail to a nail with an adhesive or 
of decorating an artificial nail or a nail using an adhesive according to 
the embodiment (1), which comprises applying a photocurable cyanoacrylate 
adhesive to a bonding surface of the nail or artificial nail or to a 
bonding surface of a decorative article or of the nail or artificial nail, 
subsequently superposing the adherends on each other, and then irradiating 
the superposed adherends with light to cure the adhesive and complete the 
bonding. 
(3) The method of bonding an artificial nail to a nail with an adhesive or 
of decorating an artificial nail or a nail using an adhesive according to 
the embodiment (1) or (2), wherein the photocurable cyanoacrylate adhesive 
comprises: 
(A) an .alpha.-cyanoacrylate and 
(B) a metallocene compound comprising a transition metal of Group VIII of 
the periodic table and aromatic electron system ligands. 
(4) The method of bonding an artificial nail to a nail with an adhesive or 
of decorating an artificial nail or a nail using an adhesive according to 
the embodiment (3), wherein each of the aromatic electron system ligands 
in the metallocene compound (B) is a .pi.-arene, indenyl, or 
.eta.-cyclopentadienyl. 
(5) The method of bonding an artificial nail to a nail with an adhesive or 
of decorating an artificial nail or a nail using an adhesive according to 
the embodiment (3), wherein the metallocene compound (B) comprising a 
transition metal of Group VIII of the periodic table and aromatic electron 
system ligands is represented by the following formula (1): 
##STR1## 
(wherein M represents a transition metal of Group VIII of the periodic 
table; R represents a halogen atom, a hydrocarbon group having 1 to 20 
carbon atoms, a halogenated hydrocarbon group having 1 to 20 carbon atoms, 
or a silicon-atom containing, oxygen-atom containing, sulfur-atom 
containing, or phosphorus-atom containing group having 1 to 20 carbon 
atoms, provided that the R's may be the same or different and may be 
crosslinked to each other; symbol a represents an integer of from 0 to 5; 
and the groups R.sub.a --Cp! (Cp represents .eta.-cyclopentadienyl) may 
be the same or different). 
(6) The method of bonding an artificial nail to a nail with an adhesive or 
of decorating an artificial nail or a nail using an adhesive according to 
the embodiment (3), wherein the transition metal of Group VIII of the 
periodic table in the metallocene compound (B) is a transition metal 
selected from the group consisting of iron, osmium, ruthenium, cobalt and 
nickel. 
(7) The method of bonding an artificial nail to a nail with an adhesive or 
of decorating an artificial nail or a nail using an adhesive according to 
any of the embodiments (3) to (6), wherein the photocurable cyanoacrylate 
adhesive further comprises (C) a cleavage-type photoinitiator. 
(8) The method of bonding an artificial nail to a nail with an adhesive or 
of decorating an artificial nail or a nail using an adhesive according to 
the embodiment (1) or (2), wherein the photocurable cyanoacrylate adhesive 
comprises: 
(A) an .alpha.-cyanoacrylate and 
(B) an acetylacetonatoplatinum(II) complex. 
(9) The method of bonding an artificial nail to a nail with an adhesive or 
of decorating an artificial nail or a nail using an adhesive according to 
the embodiment (1) or (2), wherein the photocurable cyanoacrylate adhesive 
comprises: 
(A) an .alpha.-cyanoacrylate and 
(B) a metal complex which releases a nucleophilic agent upon light 
irradiation. 
The photocurable cyanoacrylate adhesive composition for use in the present 
invention is generally obtained from a composition consisting mainly of an 
.alpha.-cyanoacrylate monomer represented by formula (2): 
EQU H.sub.2 C.dbd.C(CN)--COOR (2) 
(wherein R represents an ester residue, examples of which include an alkyl 
group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group, an 
alkynyl group, and an aryl group, and which usually has from 1 to 8 carbon 
atoms, although the number of carbon atoms thereof is not particularly 
limited; the ester residue may be a substituted hydrocarbon group such as 
an alkoxyalkyl group or a trialkylsilylalkyl group) by adding to the 
composition a catalyst capable of polymerizing and curing the 
.alpha.-cyanoacrylate monomer with the aid of light irradiation. Examples 
of the photocurable cyanoacrylate adhesive composition according to the 
present invention include the following compositions 1) to 4). 
1) A cyanoacrylate adhesive composition comprising the following 
ingredients (A) and (B): 
(A) an .alpha.-cyanoacrylate and 
(B) a metallocene compound comprising a transition metal of Group VIII of 
the periodic table and aromatic electron system ligands. 
2) A cyanoacrylate adhesive composition comprising the following 
ingredients (A) to (C): 
(A) an .alpha.-cyanoacrylate, 
(B) a metallocene compound comprising a transition metal of Group VIII of 
the periodic table and aromatic electron system ligands, and 
(C) a cleavage-type photoinitiator. 
3) A cyanoacrylate adhesive composition comprising the following 
ingredients (A) and (B): 
(A) an .alpha.-cyanoacrylate and 
(B) an acetylacetonatoplatinum(II) complex. 
4) A cyanoacrylate adhesive composition comprising the following 
ingredients (A) and (B): 
(A) an .alpha.-cyanoacrylate and 
(B) a specific metal complex which releases a nucleophilic agent upon light 
irradiation.

DETAILED DESCRIPTION OF THE INVENTION 
The .alpha.-cyanoacrylate monomer contained in the photocurable 
cyanoacrylate adhesive composition for use in the present invention is 
then explained below in detail. The .alpha.-cyanoacrylate is a monomer 
represented by formula (2): 
EQU H.sub.2 C.dbd.C(CN)--COOR (2) 
(wherein R represents an ester residue, examples of which include an alkyl 
group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group, an 
alkynyl group, and an aryl group, and which usually has from 1 to 8 carbon 
atoms, although the number of carbon atoms thereof is not particularly 
limited; the ester residue may be a substituted hydrocarbon group such as 
an alkoxyalkyl group or a trialkylsilylalkyl group). Examples of the 
.alpha.-cyanoacrylate monomer include alkyl and cycloalkyl 
.alpha.-cyanoacrylates such as methyl .alpha.-cyanoacrylate, ethyl 
.alpha.-cyanoacrylate, propyl .alpha.-cyanoacrylate, butyl 
.alpha.-cyanoacrylate, and cyclohexyl .alpha.-cyanoacrylate; alkenyl and 
cycloalkenyl .alpha.-cyanoacrylates such as allyl .alpha.-cyanoacrylate, 
methallyl .alpha.-cyanoacrylate, and cyclohexenyl .alpha.-cyanoacrylate; 
alkynyl .alpha.-cyanoacrylates such as propargyl .alpha.-cyanoacrylate; 
aryl .alpha.-cyanoacrylates such as phenyl .alpha.-cyanoacrylate and tolyl 
.alpha.-cyanoacrylate; heteroatom-containing .alpha.-cyanoacrylates such 
as methoxyethyl .alpha.-cyanoacrylate, ethoxyethyl .alpha.-cyanoacrylate, 
and furfuryl .alpha.-cyanoacrylate; and silicon atom-containing 
.alpha.-cyanoacrylates such as trimethylsilylmethyl .alpha.-cyanoacrylate, 
trimethylsilylethyl .alpha.-cyanoacrylate, trimethylsilylpropyl 
.alpha.-cyanoacrylate, and dimethylvinylsilylmethyl .alpha.-cyanoacrylate. 
Examples of catalysts usable for imparting photocurability to the 
.alpha.-cyanoacrylate monomer described above include: 
(a) a metallocene compound comprising a transition metal of Group VIII of 
the periodic table and aromatic electron system ligands, 
(b) a mixed catalyst consisting of a combination of a cleavage-type 
photoinitiator and a metallocene compound comprising a transition metal of 
Group VIII of the periodic table and aromatic electron system ligands, 
(c) an acetylacetonatoplatinum(II) complex, and 
(d) a specific metal complex which releases a nucleophilic agent upon light 
irradiation. 
The above described (a) metallocene compounds comprising a transition metal 
of Group VIII of the periodic table and aromatic electron system ligands 
are represented by the following formula (1): 
##STR2## 
(In the formula, M represents a transition metal of Group VIII of the 
periodic table. R represents a halogen atom, a hydrocarbon group having 1 
to 20 carbon atoms, a halogenated hydrocarbon group having 1 to 20 carbon 
atoms, or a silicon atom-containing, oxygen atom-containing, sulfur 
atom-containing, or phosphorus atom-containing group having 1 to 20 carbon 
atoms, provided that the R's may be the same or different and may be 
crosslinked to each other. Symbol a represents an integer of from 0 to 5.) 
In formula (1), the groups R.sub.a --Cp! (Cp represents 
.eta.-cyclopentadienyl) may be the same or different. 
The metallocene compound comprising a transition metal of Group VIII of the 
periodic table and aromatic electron system ligands is not particularly 
limited in its aromatic electron system ligands. Preferable examples of 
the ligands include .pi.-arenes, indenyl, and .eta.-cyclopentadienyl. 
Particularly preferred of these is .eta.-cyclopentadienyl. Examples of 
substituents which may be bonded to each ligand include halogen atoms, 
hydrocarbon groups having 1 to 20 carbon atoms, halogenated hydrocarbon 
groups having 1 to 20 carbon atoms, and silicon atom-containing, oxygen 
atom-containing, sulfur atom-containing, and phosphorus atom-containing 
groups having 1 to 20 carbon atoms. Each ligand may have the same or 
different substituents, and the substituents may be crosslinked to each 
other. 
Preferable transition metals for the metallocene compound comprising a 
transition metal of Group VIII of the periodic table and aromatic electron 
system ligands include iron, osmium, ruthenium, cobalt and nickel. 
Examples of the metallocene compound comprising a transition metal of 
Group VIII of the periodic table and aromatic electron system ligands for 
use in the present invention are shown below. These compounds may be used 
either alone or as a mixture of two or more thereof. 
(e) Examples of compounds having one or more halogen atom substituents 
include 4-acetyl-1'-bromo-1,2-diethylferrocene, 
1'-bromo-1,2,3-triethylferrocene, 1-acetyl-1'-bromo-2,3-diethylferrocene, 
1-iodo-1'-(4-methoxyphenyl)ferrocene, and 
1-bromo-1'-(ethoxycarbonyl)ferrocene. 
(f) Examples of compounds having one or more hydrocarbon group substituents 
having 1 to 20 carbon atoms include 1,1'-dimethylferrocene, 
1,1'-di-n-butylferrocene, bis(pentamethylcyclopentadienyl)iron, 
1,1'-diethylferrocene, 1,1-dipropylferrocene, 1,1'-di-n-pentylferrocene, 
1,1'-di-n-hexylferrocene, 1,1',2-trimethylferrocene, 
1,1',2-triethylferrocene, 1,1',2-tripropylferrocene, 
1,1',2-tri-n-butylferrocene, 1,1',2-tri-n-pentylferrocene, 
1,1',2-tri-n-hexylferrocene, 1,1',3-trimethylferrocene, 
1,1',3-triethylferrocene, 1,1',3-tripropylferrocene, 
1,1',3-tri-n-butylferrocene, 1,1',3-tri-n-pentylferrocene, 
1,1',3-tri-n-hexylferrocene, 1,1',2,3'-tetramethylferrocene, 
1,1',2,3'-tetraethylferrocene, 1,1',2,3'-tetrapropylferrocene, and 
1,1',2,3'-tetra-n-butylferrocene. 
(g) Examples of compounds having one or more halogenated hydrocarbon group 
substituents having 1 to 20 carbon atoms include 
1-methyl-1'-(chloromethyl)ferrocene, 1-chloro-1'-(chloromethyl)ferrocene, 
1-methyl-1'-(bromomethyl)ferrocene, 1-methyl-1'-(iodomethyl)ferrocene, 
1,1'-di(chloromethyl)ferrocene, 1,1',2-tri(chloromethyl)ferrocene, 
1,1',2,2'-tetra(chloromethyl)ferrocene, 
bis(pentachloromethylcyclopentadienyl)iron, and 
bis(pentabromomethylcyclopentadienyl)iron. 
(h) Examples of compounds having one or more silicon atom-containing group 
substituents having 1 to 20 carbon atoms include 
1-methyl-1'-(trimethylsilylmethyl)ferrocene, 
1-methyl-1'-(trimethylsilylethyl)ferrocene, 
1-methyl-1'-(trimethylsilylpropyl)ferrocene, 
1,1'-di(trimethylsilylmethyl)ferrocene, 
1,1'-di(trimethylsilylethyl)ferrocene, 
1,1'-di(dimethylsilylmethyl)ferrocene, 
1-acetyl-1'-(trimethylsilylmethyl)ferrocene, 
1,1'-diacetyl-2-(trimethylsilylmethyl)ferrocene, and 
1,1'-diacetyl-3-(trimethylsilylmethyl)ferrocene. 
(i) Examples of compounds having one or more oxygen atom-containing group 
substituents having 1 to 20 carbon atoms include 
1,1'-di(acetylcyclopentadienyl)iron, 1,1'-dibenzoylferrocene, 
1,1'-bis(1-oxonyl)ferrocene, 1,1'-bis(1-oxooctadecyl)ferrocene, 
1,1'-bis(1-oxohexyl)ferrocene, 1-acetyl-1'-ethynylferrocene, ferrocenyl 
vinyl ketone, ferrocenylmethyl methacrylate, and ferrocenyl vinyl ether. 
(j) Examples of compounds having one or more sulfur atom-containing group 
substituents having 1 to 20 carbon atoms include 
1,1'-bis(4-mercapto-1-oxobutyl)ferrocene, 
1-(2-phenylethyl)-1'-(2-thienylcarbonyl)ferrocene, 
1-ethyl-3-(1-hydroxyethyl)-1'-(2-thienylcarbonyl)ferrocene, 
1-(phenylacetyl)-1'-(2-thienylcarbonyl)ferrocene, 
1-benzoyl-1'-(2-thienylcarbonyl)ferrocene, 
1-acetyl-1'-(methoxysulfonyl)ferrocene, and 1-acetyl-1'-sulfoferrocene. 
(k) Examples of compounds having one or more phosphorus atom-containing 
group substituents having 1 to 20 carbon atoms include 
1,1'-bis(diphenylphosphino)ferrocene, 
1-acetyl-1'-((diphenylphosphino)acetyl)ferrocene, 
1,1'-bis((diphenylphosphino)acetyl)ferrocene, 
1-(diphenylphosphino)-1'-formylferrocene, 
1-acetyl-1'-(diphenylphosphino)ferrocene, and 
1-acetyl-1'-(diphenylphosphinyl)ferrocene. 
(l) Examples of compounds having substituents crosslinked to each other 
include 1,1'-diacetyl-2,3'-(1,3-propanediyl)ferrocene, 
1,2-diacetyl-1,4'-(1,4-butanediyl)ferrocene, 
1,1'-bis(methoxycarbonyl)-2,2'-(oxybis(methylene))ferrocene, and 
1,1'-bis(ethoxycarbonyl)-2,2'-(oxybis(methylene))ferrocene. 
In the mixed catalyst (b) for use in the present invention, which consists 
of a combination of a cleavage-type photoinitiator (accelerator) and a 
metallocene compound comprising a transition metal of Group VIII of the 
periodic table and aromatic electron system ligands, the metallocene 
compound comprising a transition metal of Group VIII of the periodic table 
and aromatic electron system ligands is the same as described above with 
regard to (a). Examples of the cleavage-type photoinitiator include the 
photoinitiators enumerated below under (i) to (iii). These photoinitiators 
may be used either alone or as a mixture of two or more thereof. 
(i) Examples of acetophenone photoinitiators include 
4-phenoxydichloroacetophenone, 4-t-butyldichloroacetophenone, 
4-t-butyltrichloroacetophenone, diethoxyacetophenone, 
2-hydroxy-2-methyl-1-phenylpropan-1-one, 
1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 
1-(4-dodecylphenyl)-2-hydroxy-2-methylpropan-1-one, 
4-(2-hydroxyethoxy)phenyl (2-hydroxy-2-propyl) ketone, 1-hydroxycyclohexyl 
phenyl ketone, and 
2-methyl-1-(4-(methylthio)phenyl)-2-morpholinopropane-1. 
(ii) Examples of benzoin photoinitiators include benzoin, benzoin methyl 
ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl 
ether, and benzoin methyl ketal. 
(iii) Examples of other photoinitiators include .alpha.-acyloxime esters, 
acylphosphine oxides, methylphenyl glyoxylate, 3,3',4,4'-tetra(t-butyl 
peroxycarbonyl)benzophenone, and 2,2'-azobis(2-methylbutyronitrile). 
Examples of the acetylacetonatoplatinum(II) complex for use in imparting 
photocurability to a cyanoacrylate adhesive composition include 
Pt(acac).sub.2. 
Examples of the specific metal complex releasing a nucleophilic agent upon 
light irradiation which is usable for imparting photocurability to a 
cyanoacrylate adhesive composition include the following compounds: 
trans-Cr(NH.sub.2).sub.2 (NCS).sub.4 !.sup.- 
trans-Cr(en).sub.2 (NCS).sub.2 !.sup.+ 
trans-Co(en).sub.2 Cl.sub.2 !.sup.+ 
trans-Cr(cyclam)Cl.sub.2 !.sup.+ 
trans-Cr(cyclam)(NCS).sub.2 !.sup.+ 
trans-Co(cyclam)Cl.sub.2 !.sup.+ 
wherein en represents ethylenediamine and cyclam represents 
1,4,8,11-tetraazacyclotetradecane. 
The mixing ratio of the photocurable cyanoacrylate adhesive composition of 
the present invention and the above described catalyst is not particularly 
limited as long as the amount of the catalyst is enough to photopolymerize 
the cyanoacrylate monomer. For example, in the case of using (a) the 
metallocene compound comprising a transition metal of Group VIII of the 
periodic table and aromatic electron system ligands, the metallocene 
compound is added in an amount of 10 to 100,000 ppm by weight, preferably 
30 to 50,000 ppm by weight based on the weight of the cyanoacrylate 
monomer. In the case of using (b) cleavage-type photoinitiator, the 
photoinitiator is added, in general, in an amount of 100 to 20,000 ppm by 
weight, preferably 300 to 15,000 ppm by weight based on the weight of the 
cyanoacrylate monomer, although the suitable addition amount varies 
depending on kinds and the addition amount of the metallocene compound. 
The photocurable cyanoacrylate adhesive composition for use in the present 
invention may be used in combination with a radical-polymerizable compound 
such as acrylate ester. Furthermore, the photocurable cyanoacrylate 
adhesive composition may, if necessary, further contain one or more of 
known specific additives such as anionic-polymerization inhibitors, 
radical-polymerization inhibitors, thickening agents, curing accelerators, 
plasticizers, tougheners, perfumes, dyes, pigments, fillers, and heat 
stabilizers. 
A radical-polymerizable compound such as an acrylic ester, can be added to 
the photocurable composition of the present invention. Even if a 
radical-polymerizable compound is added, the photocurable composition of 
the present invention can be rapidly cured owing to the cleavage-type 
photoinitiator. 
An anionic-polymerization inhibitor may be added in order to enhance the 
storage stability of the composition. Known examples thereof include 
sulfur dioxide, sulfur trioxide, nitrogen oxide, hydrogen fluoride, and 
p-toluenesulfonic acid. The anionic-polymerization inhibitor may be added 
in an amount of 0.1 to 10,000 ppm by weight based on the weight of the 
.alpha.-cyanoacrylate. 
Examples of radical-polymerization inhibitors include quinone, 
hydroquinone, t-butylcatechol, and p-methoxyphenol. The 
radical-polymerization inhibitor may be added in an amount of 0.1 to 
10,000 ppm by weight based on the weight of the .alpha.-cyanoacrylate. 
A thickening agents may be added in order to heighten the viscosity of the 
composition. Examples thereof include poly(methyl methacrylate), 
methacrylate copolymers, acrylic rubbers, cellulose derivatives, 
poly(vinyl acetate), and poly(.alpha.-cyanoacrylate)s. 
Many kinds of polymeric additives may be added usually for toughening. 
Examples thereof include acrylic elastomers, acrylonitrile copolymer 
elastomers, fluoroelastomers, and a fine silica filler. These substances 
function also as thickening agents. 
EXAMPLES 
The present invention will be explained below by reference to Examples and 
Comparative Examples, but the invention should not be construed as being 
limited to these Examples. The parts as used in the Examples and 
Comparative Examples and values as used in the table are by weight unless 
otherwise specified. 
In the Examples and Comparative Examples, Three Bond 1743 (product of Three 
Bond Co., Ltd.; main component: ethyl .alpha.-cyanoacrylate; hereinafter 
abbreviated as TB1743) was used as an .alpha.-cyanoacrylate. 
For the evaluation of photocurability, a 4-kw high-pressure mercury lamp 
(manufactured by ORC Manufacturing Co., Ltd.) was used as an ultraviolet 
irradiator. The photocurability of each of the compositions was evaluated 
by placing 1 g of a sample in a polyethylene tray with an inner diameter 
of 30 mm and irradiating the sample with light from a distance of 15 cm to 
measure the integrated quantity of light needed for curing. The results of 
a photocurability test shown in the Examples and Comparative Examples are 
given in terms of the integral of the quantity of light needed for 
complete photocuring. 
The following abbreviations are used in the following Examples and 
Comparative Example. 
Transition metal metallocene compounds: 
______________________________________ 
Ferrocene Cp.sub.2 Fe 
1,1'-Diacetylferrocene (AcCp).sub.2 Fe 
Bis(pentamethylcyclopentadienyl)osmium 
(Me.sub.5 Cp).sub.2 Os 
Ruthenocene Cp.sub.2 Ru 
Cleavage-type photoinitiator: 
Acylphosphine oxide APO 
Irgacure 184 (Ciba-Geigy Ltd.) 
Irg184 
______________________________________ 
TABLE 1 
______________________________________ 
Comp. 
Ex. 1 
Ex. 2 Ex. 3 Ex. 4 Ex. 5 
Ex. 6 
Ex. 1 
______________________________________ 
TB1743 100 100 100 100 100 100 100 
Cp.sub.2 Fe 
5 0.5 0.5 
(AcCp).sub.2 Fe 0.1 
(Me.sub.5 Cp).sub.2 Os 0.1 
Cp.sub.2 Ru 0.01 
APO 0.1 
Irg184 1 
Photocurability 
2000 1000 1000 2000 1000 2000 30000&lt; 
______________________________________ 
Examples 1 to 4 
Samples each consisting of TB1743 and any of various transition metal 
metallocene compounds were prepared according to formulations shown in 
Table 1 as follows. A hundred grams of TB1743 was placed in a 200-ml 
beaker, and the contents were stirred with Three-One Motor at 300 rpm. 
Thereto was added the given amount of each of the transition metal 
metallocene compounds little by little. Each resulting mixture was 
continuously stirred at room temperature for 1 hour to dissolve the 
metallocene compound. These samples were prepared in a dark room, and were 
stored in light-shielded containers. 
Examples 5 and 6 
Samples each consisting of TB1743, Cp.sub.2 Fe, and a cleavage-type 
photoinitiator were prepared according to formulations shown in Table 1 as 
follows. A hundred grams of TB1743 was placed in a 200-ml beaker, and the 
contents were stirred with Three-One Motor at 300 rpm. A cleavage-type 
photoinitiator was added thereto and dissolved with stirring. In the case 
where the cleavage-type photoinitiator was APO, it was dissolved by 
stirring the mixture first at 50.degree. C. for 8 hours and then at room 
temperature overnight. In the case where the cleavage-type photoinitiator 
was Irg184, it was dissolved by stirring the mixture at room temperature 
for 1 hour. Subsequently, the given amount of Cp.sub.2 Fe was added to 
each solution little by little, and was dissolved by continuously stirring 
each resulting mixture at room temperature for 1 hour. These samples were 
prepared in a dark room, and were stored in light-shielded containers. 
Comparative Example 1 
As a comparative example, results of the evaluation of TB1743 alone are 
shown. 
Subsequently, each of the adhesive compositions shown in Examples 1 to 6 
and Comparative Example 1 was used for the bonding of an artificial nail 
(product of Lee Pharmaceuticals Co., U.S.A.) to a nail to measure the 
curing time. Each adhesive composition was further evaluated for 
suitability for the building up of the adhesive at the joint between the 
nail and the artificial nail as follows. Each adhesive composition was 
applied to the joint between the nail and artificial nail, and the applied 
composition was irradiated with light to measure the time required for the 
adhesive to cure. As light sources were used a 100-W high-pressure mercury 
lamp spot irradiator (QRU-2266, manufactured by Oak Manufacturing Co., 
Ltd.) and a metal halide illuminant spot irradiator having an illuminance 
of 1,400,000 1.times. (ML60, manufactured by HOYA-SCHOTT Co.). The results 
obtained are shown in Table 2. 
TABLE 2 
______________________________________ 
Comp. 
Ex. 1 
Ex. 2 Ex. 3 Ex.4 Ex. 5 
Ex. 6 
Ex. 1 
______________________________________ 
Nail/artificial 
5-10 5-10 5-10 5-10 5-10 5-10 5-10 
nail banding 
time (sec) 
Curing time in 
15 10 10 15 10 15 uncured 
joint filling in 300 
(sec) 
High-pressure 
mercury lamp 
Metal halide 
90 60 60 70 60 70 uncured 
illuminant in 300 
______________________________________ 
Table 2 shows that the photocurable .alpha.-cyanoacrylate adhesives 
according to the present invention had the same nail/artificial nail 
bonding performance as the conventional .alpha.-cyanoacrylate adhesive and 
were capable of being rapidly cured by light irradiation. Therefore, the 
adhesives according to the present invention can also be used not only for 
the filling (or building up) of the recessed part of the a nail/artificial 
nail joint but as a coating agent for finishing or as an adhesive for 
bonding a decorative article for an artificial nail, for which the 
conventional .alpha.-cyanoacrylate adhesive has been unusable. 
The photocurable cyanoacrylate adhesive according to the present invention 
applied for bonding a nail to an artificial nail or for bonding a 
decorative article to a nail or artificial nail can be cured speedily even 
when it has been applied thickly (for building up) or has flowed out of 
the bonding part, in which case conventional cyanoacrylate adhesives 
require much time for curing. This is because the adhesive according to 
the present invention which has been applied in such a manner that rapid 
curing is difficult for conventional cyanoacrylate adhesives can be cured 
in an extremely short time period by irradiation with light. The 
photocurable cyanoacrylate adhesive according to the present invention has 
an excellent effect that it is usable not only as an adhesive for 
nail/artificial nail bonding, but also for the filling (or building up) of 
the recessed part of a nail/artificial nail joint, as a coating agent for 
finishing, or as an adhesive for bonding a decorative article to an 
artificial nail, while retaining the excellent features of the 
instantaneous adhesive, i.e., cold-setting and single-liquid type. Due to 
the above, the whole process for artificial-nail attachment beginning with 
the bonding of an artificial nail and ending with finishing can be carried 
out with only one .alpha.-cyanoacrylate adhesive, in contrast to the 
conventional process for artificial-nail attachment in which two or more 
adhesives should be used according to uses. As a result, the 
troublesomeness of artificial-nail attachment can be eliminated and the 
efficiency of the procedure can be greatly improved. 
While the invention has been described in detail and with reference to 
specific embodiments thereof, it will be apparent to one skilled in the 
art that various changes and modifications can be made therein without 
departing from the spirit and scope thereof.