Conventional nail cosmetic compositions providing a good gloss finish generally contain, as essential components, cellulose derivatives such as nitrocellulose and cellulose acetate, resins such as acrylic resins, acryl resins, and toluenesulfona ide resins, polyvinyl acetates, plasticizers, solvents, matting agents such as silica and, optionally, other conventional additives, such as pigments, dyes, and pearlescents. These types of nail cosmetic compositions have a good coatability or applicability to the nail surfaces and provide a good finish.

In order to maintain the various components in solution and to insure adequate coating and hardening characteristics, coating compositions such as nail coating compositions usually also include significant percentages

of organic solvents in amounts up to and including 80% by total composition volume. Such solvents are generally chosen for their rapid evaporation rates and ability to solubilize the other constituents. Although nail coatings as described above can provide a good finish and can provide aesthetically pleasing shades of color by mixing various pigments, there has been a long felt need in the nail cosmetic industry for a novel and pleasing nail formulation, aside from just different shades of color.

Innon-cosmetic areas, thermochromic compositions have recently been discovered, such as that disclosed in U.S. Patent No. 4,717,710 issued to Shimizu and assigned to the Matsui Shikiso Chemical Company, Ltd. of Japan, which is incorporated herein by reference. This thermochromic composition instantaneously changes color at a certain temperature. The color change is repeatedly reversible. However, the Shimizu reference discloses use of the thermochromic composition only in permanent applications such as printing inks, textiles, injection molded plastics, metallic strips, etc. In all of the listed uses, after application of the thermochromic material, the substance had to be either dried or heat treated for substantial periods of time, or a suitable curing agent had to be admixed with the thermochromic composition. Thus, the disclosure does not teach or suggest, and indeed, for the above reasons, it would appear unfeasible and undesirable to use the thermochromic composition in removable applications, such as in coating formulations for human nails.

U.S. Patent No. 4,920,991 issued to Shibahashi discloses a thermochromic artificial nail having provided thereon a thermochromic layer including a thermochromic material changeable in visible external color in response to a temperature change. However, since the thermochromic material used is formed of microcapsules, these must be dispersed using a suitable dispersing agent and fixed in a

binder in the dispersed state so as to form the thermochromic layer. Further, since the thermochromic layer is applied to an artificial nail which will not generally exhibit a temperature differential between the portion of the nail which is covering the natural nail bed and the free edge portion extending beyond the nail bed, the two portions of the artificial nail will generally be the same shade of color, either before or after the heat responsive color change. In addition to the dispersing agent that must be used, the Shibahashi reference also discloses that an acrylic resin/amine curing agent must be used in order to suitably harden the thermochromic layer.

Even though the above-mentioned thermochromic artificial nail exhibits a novel and desirable color change which can beautify the fingernails, it is undesirable to keep the artificial nails covering the fingernails over extended periods because of harmful effects, such as the suppression of blood circulation in the underlying tissues. Therefore, it is desired for one to remove the artificial nails from the nail surfaces at appropriate intervals, for example, at least once per week. However, due to the expense and time-intensive process involved in preparing and applying artificial nails, most wearers keep these artificial nails on for longer than recommended periods of time.

Thus, it would be desirable to provide a nail coating composition which will respond to temperature by changing color. It would further be desirable to provide such a composition which can quickly and easily be removable, as by suitable and conventionally known nail coating removers. Still further, it would be desirable to provide such a formulation which utilizes thermochromic pigments without the addition of dispersing agents and without having to heat treat or cure the formulation over substantial periods of time. It would further be desirable

to provide a thermochromic nail formulation which can provide a two-toned nail color at certain temperatures.

SUMMARY OF THE INVENTION The present invention addresses and solves all the problems enumerated above by providing a thermochromic nail composition. The composition is a nail lacquer consisting essentially of an alcohol selected from the group consisting of isopropyl alcohol, butyl alcohol and mixtures thereof; a solvent selected from the group consisting of butyl acetate, acetone, toluene, and mixtures thereof; a plasticizer selected from the group consisting of dioctyl phthalate, dioctyl terephthalate, butyl benzyl phthalate, and mixtures thereof; a cellulose derivative selected from the group consisting of nitrocellulose, cellulose acetate propionate, cellulose acetate, ethyl cellulose, and mixtures thereof; a selected pigment not responsive to thermal changes; and a thermochromic pigment consisting essentially of an electron-donating chromogenic material, a 1,2,3-triazole compound, a weakly basic, sparingly soluble azomethine or carboxylic acid primary amine salt, and an alcohol, amide or ester serving as a solvent.

The nail lacquer of the present invention can be stored, applied and removed as with conventional nail enamels and coatings. When in use on a wearer's nail, when the nail bed is above approximately 86°F and the free edge of the nail is below approximately 86°F _r the nail over the nail bed will have undergone a color change, whereas the free edge will not have, thereby giving a nail having a two-toned effect. Where both the nail bed and the free edge are below approximately 86°F, neither portion of the nail will have undergone any color change, thereby giving the appearance of a solid color. Where both the nail over the nail bed and the free edge are above approximately 86°F _f both portions of the nail will have undergone the color change, also giving the effect of a solid color, yet

in a different shade than in the example cited immediately above.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This invention is predicated on the unexpected discovery that thermochromic compositions such as that disclosed in U.S. Patent No. 4,717,710 can be successfully utilized in a nail coating composition or lacquer, while still retaining its color changing abilities in response to variations in temperature. The present invention comprises a thermochromic composition or lacquer for application on a selected surface, including human or artificial nails. The thermochromic composition consists essentially of an alcohol selected from the group consisting of isopropyl alcohol, butyl alcohol, and mixtures thereof. Preferably, the isopropyl alcohol, when in a basecoat, comprises 5 to 7% of the composition, and when in a color composition, between about 5 and about 8% of the composition; the butyl alcohol, when in a base composition, comprises between about 1 and 3% of the composition, and when in a color composition, comprises between about 1 and 2% of the composition. It is to be understood that any appropriate alcohol may be used having suitable solvent characteristics and a boiling point approximately between 70°C and 130°C. The composition further consists essentially of a solvent selected from the group consisting of butyl acetate, acetone, toluene, and mixtures thereof. Again, it is to be understood that any suitable solvent having characteristics typical of those compounds listed here are contemplated as being successfully employed in the practice of the present invention. Preferably, the butyl acetate, when in a base, comprises between about 26 and about 34% of the composition, and when in a color composition, comprises between about 17% and about 28% of the composition; the acetone, when in a base, comprises between about 7 and about 10% of the composition, and when in a color composition, comprises between about 5 and about 7% of the

composition; the toluene, when in a base composition, comprises between about 26 and about 34% of the composition, and when in a color composition, comprises between about 17% and about 28% of the composition. A plasticizer is admixed in the present composition in an amount sufficient to impart flexibility and wear-resistance to the composition when applied to the selected surface, the plasticizer being selected from the group consisting of dioctyl phthalate, dioctyl terephthalate, dibutyl phthalate, butyl benzyl phthalate, and mixtures thereof. Preferably, the plasticizer used is commercially available from Eastman Chemical Products, Inc. under the trade name KODAFLEX ^® DOP. Also preferable is KODAFLEX ^® DBP; SANTICIZER 160 (butyl benzyl phthalate) commercially available from Monsanto, Inc. However, it is to be understood that any suitable plasticizer may be used. The plasticizer comprises approximately 4 to 8% of the composition when used in a basecoat, and approximately 4 to 7% when used in a color composition. The thermochromic composition further comprises a cellulose derivative- present in an amount sufficient to impart composition hardness upon solidification after the composition has been applied to the selected surface, and to impart resin medium to the composition during storage and application. The cellulose derivative is selected from the group consisting of nitrocellulose, cellulose acetate propionate, cellulose acetate, ethylcellulose, andmixtures thereof. In the basecoat, preferably cellulose acetate propionate is used, commercially available from Eastman Chemical Products, Inc. under the trade name CAP-482-0.5 and CAP 482-20. CAP 482-0.5 has a higher percentage of hydroxyl groups, but a lower viscosity than CAP 482-20. Nitrocellulose resins can be substituted for the CAP's, with adjustment of the amount of plasticizer. However, nitrocellulose resins are more brittle than CAP's, and require stronger solvents for solubility in order to form lacquers. In the base, the CAP 482-0.5 comprises

approximately 14 to 18% of the base, and CAP 482-20 comprises between about 1 and 2% of the composition. In the color compositions, preferably the CAP's are also used, with the CAP 482-0.5 comprising between about 10 and about 14% of the composition, and the CAP 482-20 comprising between about 1 and 2% of the composition. In the color compositions, nitrocellulose is also preferably added, under the trade designation RS 18-25 cps, commercially available from Hercules (30% solids in MEK) . The RS 18-25 cps comprises between about 14% and about 18% of the composition.

The thermochromic composition further comprises a thermochromic pigment present in an amount sufficient to visibly change the color of the applied composition at and above a predetermined temperature, the thermochromic pigment consisting essentially of an electron-donating chromogenic material, a 1,2,3-triazole compound, a weakly basic, sparingly soluble azomethine or carboxylic acid primary amine salt, and an alcohol, amide or ester serving as a solvent. The thermochromic pigment of choice is commercially available from Matsui International Company, Inc., under the trade designation CHROMIC COLOR "HISTORY" TYPE heat sensitive convertible colorants. These are available in a variety of colors, with all colors changing from color to color, or color to colorless, at predetermined temperatures. The thermochromic pigment, in the color compositions, can comprise between about 1% and 2% of the composition, or between about 2% and about 4% of the composition. It is to be understood that any number of the thermochromic pigments may be used in a color composition according to the present invention, in appropriate percentages.

The thermochromic composition may optionally consist essentially of a non-thermochromic pigment present in an amount sufficient to impart visible color to the composition at any temperature. Preferable examples of these are Pearl Pigment 159 and Pearl Pigment 225, both

commercially available from EM Industries, Inc. , an associate of E. Merk, Darmstadt, West Germany. These pigments, in the color compositions, can comprise between about 2% and about 4% of the composition. Other suitable examples comprise Aurora Pink T-ll, commercially available from Day-Glo Color Corporation, and Naphthanil Red RT-531- D, commercially available from Heubach Incorporated. Other suitable pigments which can be successfully substituted for the Pearl Pigments 159 and 225 are commercially available from Kemira Oy Company, under the trade name FLONAC Luster Colors.

The resulting thermochromic composition can change from a first color to a second color, or from a color to colorless at a specific predetermined temperature. The temperature will depend upon the temperature range of the pigment type. The composition may undergo an instantaneous color change. Due to external variations in temperature in relation to body temperature and the like, the entire nail may be the first color or the second color, and portions of the nail (i.e. the nail covering the nail bed and the free edge of the nail extending beyond the finger) may be the first color, while other portions may be the second color, thereby giving a two- or multiple-toned effect. While preferred forms and arrangements of parts have been discussed, it is to be understood that various changes in detail for application to various surfaces are to be considered within the scope and spirit of this disclosure. To further illustrate the composition, the following examples are given. It is to be understood that these examples are provided for illustrative purposes and are not to be construed as limiting the scope of the present invention.

EXAMPLE I A lacquer base was prepared by admixing the following materials, given in weight percentages: 6.45% isopropyl alcohol; 29.69% butyl acetate; 30.49% toluene; 9.10% acetone; 1.16% butyl alcohol; 6.45% DOP plasticizer commercially available from Eastman Chemical Products, Inc. under the trade name KODAFLEX ^® DOP; 16.13% cellulose acetate propionate commercially available from Eastman Chemical Products, Inc. under the trade name CAP-482-0.5; 0.53% cellulose acetate propionate commercially available from Eastman Chemical Products, Inc. under the trade name CAP-482-20.

The resulting material was a clear lacquer which was decanted into a suitable storage vessel. The lacquer was usable as a colorless basecoat for application to human or artificial nails. Upon application to a human nail, the lacquer exhibited good wearability, spread evenly, and exhibited superior chip resistance to other clear lacquers now available on the market. EXAMPLE II

A thermochromic color lacquer was prepared by admixture of the following materials, given in weight percentages: 5.0% isopropyl alcohol; 23.0% butyl acetate; 23.23% toluene; 7.05% acetone; 0.90% butyl alcohol; 5.0% DOP plasticizer, commercially available from Eastman Chemical Products, Inc. under the trade name KODAFLEX ^® DOP; 17.62% nitrocellulose (30% solids in methylethylketone) commercially available from Hercules under the trade designation RS 18-25 cps; 2.64% Pearl Pigment 159, commercially available from EM Industries, Inc. , an associate of E. Merk, Darmstadt, West Germany; 2.64% thermochromic magenta, commercially available from Matsui International Company, Inc.; 12.50% CAP 482-0.5; 0.42% CAP 482-20. The resulting nail color lacquer was applied to a human nail. At temperatures below about 86°F, the nail appeared a light pink color. When the portion of the nail

covering the nail bed was above approximately 86°F, that portion of the nail appeared pearl white. When the free edge portion of the nail was still below approximately 86°F, it remained the light pink color, thereby giving the nail a two-toned effect. When both portions of the nail were above approximately 86°F, the entire nail appeared pearl white.

Upon application to a human nail, the lacquer exhibited good wearability, spread evenly, and exhibited superior chip resistance to other color lacquers now available on the market.

EXAMPLE III A thermochromic color lacquer is prepared by admixture of the following materials, given in weight percentages: 5.0% isopropyl alcohol; 23.0% butyl acetate; 23.63% toluene; 7.05% acetone; 0.90% butyl alcohol; 5.0% KODAFLEX ^® DOP; 17.72% RS 18-25 cps nitrocellulose; 2.66% Pearl Pigment 225 commercially available from EM Industries, Inc., an associate of E. Merk, Darmstadt, West Germany; 1.77% thermochromic magenta and 0.35% thermochromic blue, both commercially available from Matsui International Company, Inc.; 12.50% CAP 482-0.5; 0.42% CAP 482-20.

The resulting nail color lacquer is applied to a human nail. At temperatures below about 86°F, the nail appears a purple color. When the portion of the nail covering the nail bed is above approximately 86°F, that portion of the nail appears bluish pearl. When the free edge portion of the nail is still below approximately 86°F, it remains the purple color, thereby giving the nail a two- toned effect. When both portions of the nail are above approximately 86°F, the entire nail appears bluish pearl.

EXAMPLE IV A thermochromic color lacquer is prepared by admixture of the following materials, given in weight percentages: 5.0% isopropyl alcohol; 23.0% butyl acetate; 22.09% toluene; 7.05% acetone; 0.90% butyl alcohol; 5.0%

KODAFLEX ^® DOP plasticizer; 17.50% RS 18-25 cps nitrocellulose; 6.23% thermochromic magenta commercially available from Matsui International Company, Inc.; 12.50% CAP 482-0.5; 0.42% CAP 482-20; 0.31% Aurora Pink T-ll, commercially available from Day-Glo Color Corporation.

The resulting nail color lacquer is applied to a human nail. At temperatures below about 86°F, the nail appears a dark magenta color. When the portion of the nail covering the nail bed is above approximately 86°F, that portion of the nail appears light pink. When the free edge portion of the nail is still below approximately 86°F, it remains the dark magenta color, thereby giving the nail a two-toned effect. When both portions of the nail are above approximately 86°F, the entire nail appears light pink. EXAMPLE V

A thermochromic color lacquer is prepared by admixture of the following materials, given in weight percentages: 4.70% isopropyl alcohol; 21.66% butyl acetate; 22.25% toluene; 6.64% acetone; 0.85% butyl alcohol; 4.70% KODAFLEX ^® DOP plasticizer; 13.0% RS 18r25 cps nitrocellulose; 11.78% CAP 482-0.5; 0.39% CAP 482-20; 6.87% thermochromic yellow and 1.50% thermochromic orange, both commercially available from Matsui International Company, Inc.; 0.94% of a dark magenta thermochromic nail lacquer as prepared according to EXAMPLE IV above; 4.72% of an extender, commercially available from KMG Minerals, Inc. under the trade name micromica C-3000.

The resulting nail color lacquer is applied to a human nail. At temperatures below about 86°F, the nail appears a peach color. When the portion of the nail covering the nail bed is above approximately 86°F, that portion of the nail appears light beige. When the free edge portion of the nail is still below approximately 86°F, it remains the peach color, thereby giving the nail a two- toned effect. When both portions of the nail are above

approximately 86°F, the entire nail appears light beige.

EXAMPLE VI A thermochromic color lacquer is prepared by admixture of the following materials, given in weight percentages: 5.82% isopropyl alcohol; 26.83% butyl acetate; 27.55% toluene; 8.22% acetone; 1.05% butyl alcohol; 5.83% KODAFLEX ^® DOP plasticizer; 5.95% RS 18-25 cps nitrocellulose; 1.43% thermochromic magenta and 1.78% thermochromic blue, both commercially available fromMatsui International Company, Inc.; 14.58% CAP 482-0.5; 0.48% CAP 482-20; and 0.48% Napthanil Red RT-531-D, commercially available from Heubach,. Inc.

The resulting nail color lacquer is applied to a human nail. At temperatures below about 86°F, the nail appears a burgundy color. When the portion of the nail covering the nail bed is above approximately 86°F, that portion of the nail appears light red. When the free edge portion of the nail is still below approximately 86°F, it remains the burgundy color, thereby giving the nail a two- toned effect. When both portions of the nail are above approximately 86°F, the entire nail appears light red.