| PATENT NUMBER | This data is not available for free |
| PATENT GRANT DATE | September 23, 1997 |
| PATENT TITLE |
Aqueous nitrocellulose compositions |
| PATENT ABSTRACT |
The present invention comprises aqueous cellulose solutions and methods of their making. The solutions of the invention provide coatings and can be employed as nail coatings, protective coatings and non-wax polishes. |
| PATENT INVENTORS | This data is not available for free |
| PATENT ASSIGNEE | This data is not available for free |
| PATENT FILE DATE | March 28, 1995 |
| PATENT CT FILE DATE | September 28, 1993 |
| PATENT CT NUMBER | This data is not available for free |
| PATENT CT PUB NUMBER | This data is not available for free |
| PATENT CT PUB DATE | April 14, 1994 |
| PATENT REFERENCES CITED |
Hercules Incorporated, CSL-132C "Nitrocellulose Lacquer Emulsions -Preparation and Performance for Improving Paper and Paper Products" (Apr. 1986). Hercules Incorporated, CSL-142A "Nitrocellulose Improved Water Resistance of Polyvinyl Acetate Coatings" (Apr. 1983). Hercules Incorporated, CSL-225A "Preparation Procedures for Nitrocellulose Waterborne Coatings and Inks" (Jun. 1983). Kintish, L., Soap Cosmetics Chemical Specialties, Jul.;. 29-31, 52-53, 58-59 (1992). |
| PATENT PARENT CASE TEXT | This data is not available for free |
| PATENT CLAIMS |
What is claimed is: 1. A method for preparing an aqueous cellulose composition comprising the following steps: a) mixing water and a cellulose compound selected from the group consisting of nitrocellulose, ethylcellulose and cellulose acetate butyrate in a ratio of from about 2 parts by weight water per part by weight cellulose compound to about 20 parts by weight water per part by weight cellulose compound, thereby forming a water-cellulose mixture; b) adding a glycol ether solvent to the water-cellulose mixture in a ratio of from about 2 parts by weight solvent to about 20 parts by weight solvent per part by weight cellulose compound present in the water-cellulose mixture thereby forming a water-cellulose solvent mixture; and c) mixing the water-cellulose solvent mixture thereby forming an aqueous cellulose solution. 2. The method of claim 1 wherein the step of mixing water and a cellulose compound further comprises adding the water to the cellulose compound in multiple steps. 3. An aqueous nitrocellulose solution obtained by the method of claim 1. 4. An aqueous ethylcellulose solution obtained by the method of claim 1. 5. An aqueous cellulose acetate butyrate solution obtained by the method of claim 1. 6. An aqueous cellulose solution consisting essentially of a cellulose compound selected from the group consisting of nitrocellulose, ethylcellulose and cellulose acetate butyrate, water and glycol ether solvent in a ratio of from about 2 to about 20 parts by weight water and from about 2 to about 20 parts by weight solvent, per part by weight cellulose compound. 7. An aqueous cellulose solution consisting essentially of a cellulose compound selected from the group of nitrocellulose, ethylcellulose and cellulose acetate butyrate, water and glycol ether solvent in a ratio of from about 0.5 to about 4 parts by weight water and from about 1 to about 7 parts by weight solvent, per part by weight cellulose compound. 8. An aqueous cellulose solution comprising a cellulose compound selected from the group consisting of nitrocellulose, ethylcellulose and cellulose acetate butyrate, water and glycol ether solvent in a ratio of from about 2 to about 20 parts by weight water and from about 2 to about 20 parts by weight solvent, per part by weight cellulose compound. 9. An aqueous cellulose solution comprising a cellulose compound selected from the group of nitrocellulose, ethylcellulose and cellulose acetate butyrate, water and glycol ether solvent in a ratio of from about 0.5 to about 4 parts by weight water and from about 1 to about 7 parts by weight solvent, per part by weight cellulose compound. -------------------------------------------------------------------------------- |
| PATENT DESCRIPTION |
FIELD OF THE INVENTION The present invention relates generally to aqueous cellulose compositions and, more particularly, to aqueous cellulose-based coatings and methods of making. BACKGROUND OF THE INVENTION Nitrocellulose has long been used as a base film forming material for various films and coatings. One of its many applications is in lacquer emulsions used in the manufacture of nail coatings or polishes. Nitrocellulose emulsions used in coatings are generally obtained through either direct emulsification or indirectly through various inversion techniques. For example, a conventional lacquer of nitrocellulose and solvent with emulsifiers is emulsified with the addition of water, inverting from a water-in-lacquer to a lacquer-in-water emulsion. Another inversion technique begins with water-wet nitrocellulose which is dissolved in the solvent system, with water from the mixture dispersing throughout the solvent phase. Additional water containing an emulsifying agent is added forming a lacquer-in-water emulsion by inversion. Although many improvements have been made in nail coating performance, conventional nail coatings still employ a relatively high percentage of volatile water-immiscible solvents which are relatively toxic, in order to emulsify the nitrocellulose based material. Water-miscible solvents are not ordinarily used because they promote formation of water-in-lacquer rather than lacquer-in-water emulsions. Due to the high percentage of water-immiscible solvents ordinarily employed to emulsify the nitrocellulose, the resultant coatings are flammable and potentially toxic, with a high rate of volatilization and an unpleasant odor. In addition, some individuals become sensitized and develop reactions to these nail coatings. It is therefore desirable to provide a method for preparing cellulose solutions with less reliance on a high percentage of harsh solvents. It is also desirable to provide cellulose-based compositions which have reduced environmental impact by employing a greater percentage of water. It is further desirable to provide nitrocellulose-based compositions for coatings with a lower percentage of solvent. It is further desirable to provide improved nail coatings with a lower percentage of solvents, but which do not sacrifice durability and hardness characteristics. SUMMARY OF THE INVENTION The present invention provides novel aqueous cellulose compositions and methods of making such compositions. The present invention also encompasses the use of aqueous cellulose compositions in coatings and the method of making. The coating compositions are free-flowing liquids which may be either pigmented or non-pigmented and applied to human nails in a conventional manner. The coating compositions may also be employed as polishes and protective coatings. The method for preparing cellulose in water, hereinafter "aqueous cellulose solution," generally comprises the steps of mixing solid nitrocellulose, ethylcellulose or cellulose acetate butyrate and a substantial amount of water, adding more water with continued mixing and adding a small amount of solvent with continued mixing. The water and solvent may also be added simultaneously. The above steps are performed at an elevated temperature of about 95.degree. C. to boiling. The resulting mixture is azeotropic-like. Nitrocellulose-based coatings of the present invention are obtained by mixing a proportional amount of acrylic-based polymers and aqueous nitrocellulose solution. Various additives such as wetting agents, germicides and thickeners may also be added. Pigmented coatings are formed by adding dispersed treated pigments to the nitrocellulose-based coatings. The dispersed treated pigments are obtained by repeatedly mixing the pigments with silanes, and titanates, desiccating and then, milling the treated pigments with a wetting agent and a dispersing surfactant. The nail coatings of the present invention are primarily aqueous rather than solvent-based and employ generally gentler, low volatile organic solvents. The hardness, durability and water resistance of the nail coatings of the invention are equal to or surpass those of nail coatings presently on the market. The coatings of the present invention are also less affected by humidity than solvent-based coatings. In addition, the coatings of the present invention have a high solid content (28%-43% solids), which affords better coverage of imperfections in the nail. The coatings of the present invention do not appear to form a continuous film as do solvent-based coatings and do not easily chip due to their adhesive and flexible qualities. The decrease in the high percentage of solvents reduces solvent-related problems. The coatings of the present invention also more readily permit the exchange of body fluids with the atmosphere, i.e. allowing the nail bed to "breathe." The coatings of the present invention may also be used as a polish on vinyl, leather, finished and unfinished wood, formica and flooring, including linoleum, ceramic tile, marble and mineral flooring and the like. The coatings are also useful as polishes for automobiles. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS I. Preparation of The Aqueous Cellulose Solution The aqueous cellulose solution is made with solvents selectively compatible with polymers to which it will be added, to enhance the properties of the particular polymer being used. The invention can include nitrocellulose, ethylcellulose or cellulose acetate butyrate, although it will be appreciated that in alternative embodiments, other suitable cellulose compounds or complexes may be used. Examples of solvents that may be employed in the present invention include but are not limited to propylene glycol monopropyl ether, ethylene glycol monopropyl ether, ethyl 3-ethoxypropionate, isopropyl or ethyl alcohol (32 g) with ethylene glycol monobutyl ether (26 g), dipropylene glycol monobutyl ether, dipropylene glycol methyl ether, propylene glycol methyl acetate, propylene glycol methyl ether acetate, dipropylene glycol methyl ether acetate, isopropyl acetate, N-methyl-2-pyrrolidone, isopropyl or ethyl alcohol and propylene glycol methyl ether. Examples of preferred solvents include propylene glycol monobutyl ether, ethylene glycol monobutyl acetate, ethylene glycol monobutyl ether and diethylene glycol monoethyl ether. The solvents of the present invention may also act as a freeze-thaw factor. The present invention may also employ surfactants including but not limited to El 620, available from RHONE POULENC of Cranbury, N.J., FC129 FLUORAD, available from 3M of St. Paul, Minn., SURFYNOL S-104E, available from Air Products, Inc. of Allentown, Pa., L-7001, available from Union Carbide Corp. of Danbury, Conn., and A-196, available from American Cyanamid. The invention can also include other additives such as ammonium hydroxide, 28%. The pH of the solution is in the range of from about 2.0 to about 6.0. Nitrocellulose, ethylcellulose and cellulose acetate butyrate (hereinafter referred to generally as "cellulose compounds") were put into aqueous solutions according to the following general technique wherein the amount of distilled water varied from about 2 parts by weight to about 20 parts by weight for every part by weight of cellulose compound (all measurements are based on employing an open vessel in the preparation of the compositions). The nitrocellulose was 80% by weight, water packed. Ethylcellulose and cellulose acetate butyrate were 100% by weight. An example of preferred nitrocellulose is that sold by Aqualon, a Hercules Corporation. An example of preferred ethylcellulose is that sold by Dow Chemical Co. of Midland, Mich. An example of preferred cellulose acetate butyrate is that sold by Eastman Kodak Co. of Rochester, N.Y. The solvents employed range from about 2 parts by weight to about 20 parts by weight for every part by weight of cellulose compound. The surfactants employed vary from about 0.05 g to about 1.0 g without dilution for every part by weight of cellulose compound. The general technique consists of applying heat in the range of from about 70.degree. C. to about boiling, preferably at about 95.degree. C. to about boiling and mixing at a mixer speed of around 8.5 or at a speed great enough to form a vortex in the mixture. The cellulose compound and distilled water are mixed for about five minutes. More water is added and the solution is mixed for about five more minutes. Solvent is added and mixed for about twenty more minutes. Variations of this method may be employed as illustrated by the foregoing examples with similar results obtained. |
| PATENT EXAMPLES | This data is not available for free |
| PATENT PHOTOCOPY | Available on request |
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