Cleaning and liquid contact with solids – Processes – Paints – varnishes – lacquers – or enamels – removal
Reexamination Certificate
2000-11-01
2002-11-19
Gupta, Yogendra N. (Department: 1751)
Cleaning and liquid contact with solids
Processes
Paints, varnishes, lacquers, or enamels, removal
C510S174000, C510S201000, C510S202000, C510S407000, C510S493000
Reexamination Certificate
active
06482270
ABSTRACT:
BACKGROUND OF INVENTION
This invention relates to compositions for paint and coating removal. More particularly, this invention relates to compositions containing a carbonate such as alkylene carbonate or dialkyl carbonate or both, dibasic ester and a mono-ester.
Paint removing compositions are commonly used in industry, such as for stripping paint from airplane fuselages. Conventional paint remover compositions include methylene chloride, phenol, or caustic. Each of these materials, however, has inherent problems during use. While methylene chloride based compositions are very effective as paint removers, methylene chloride is a highly volatile material which is considered toxic. Similarly, phenol is highly toxic. Furthermore, caustic causes burns and attacks aluminum. Due to the deficiencies and disadvantages of conventional paint removing compositions, new paint removing compositions are highly desirable.
SUMMARY OF INVENTION
The invention provides a solution to one or more of the problems and disadvantages discussed above.
In one broad respect, this invention is a composition useful as a paint remover, comprising: a carbonate, a dibasic ester and a mono-ester. In one embodiment, the composition may also contain an organic sulfur-containing compound, a glycol ether, a ketone, or combination thereof.
In another broad respect, this invention is a process for removing paint, comprising: applying a composition to a painted surface for a time and under conditions effective to cause blistering or bubbling of the paint, wherein the composition comprises a carbonate, a dibasic ester and a mono-ester.
In another broad respect, this invention is a process for removing a coating from a surface, comprising: providing a composition containing a carbonate, a dibasic ester and a mono-ester; adding a thickening agent to the composition and mixing the resulting composition to form a thickened composition; applying the thickened composition to a coated surface for a time sufficient and under conditions effective to separate at least a portion of the coating from the surface; and removing the coating and thickened composition from the surface.
In another broad respect, this invention is a process of the manufacture of a paint stripper, comprising: combining a carbonate, a dibasic ester and a mono-ester in amount and under conditions effective to form a miscible composition. The combining of the components may be effected as by stirring, typically at the ambient atmospheric pressure and temperature. The composition may include additional components as disclosed herein.
The surfaces to be treated may be sealed with a variety of sealants, such as polysulfide, polyurethane, lacquer, epoxy, and the like. The compositions can be used to remove paints and coatings from furniture, automobiles, boats, trains, airplanes, military vehicles, and so forth.
This invention has a number of advantages. For example, the compositions have several important attributes, including low toxicity, high efficacy in removing paint and coatings. It has further been advantageously found that the compositions may be blended with additional co-solvents, activators, corrosion inhibitors, and the like, or may be used directly to effect paint removal. Furthermore, in the case of propylene carbonate, the propylene carbonate breaks down into propylene glycol, which is non-toxic. Hence, the propylene carbonate compositions of this invention are environmentally friendly, particularly as compared to chlorinated hydrocarbons and the like which are commonly used for paint and coating removing. The compositions of this invention may advantageously be of low volatility and free of carcinogenic chemicals.
DETAILED DESCRIPTION OF THE INVENTION
The compositions of this invention contain a carbonate such as alkylene carbonate or dialkyl carbonate or both, dibasic ester and a mono-ester.
The carbonates that may be employed in the practice of this invention include alkylene carbonates and dialkyl carbonates. The alkylene carbonate used in the present invention can contain from 2 to 10 carbon atoms. Representative examples of alkylene carbonates that may be employed in the practice of this invention include ethylene carbonate and propylene carbonate. Mixtures of carbonates may also be employed. In the practice of this invention, alkylene carbonates are preferred, and among the alkylene carbonates propylene carbonate is preferred. The dialkyl carbonate used in the present invention may contain from 3 to 25 carbon atoms. The dialkyl carbonate may be of formula R—CO
3
—R′, wherein R and R′ may be the same or different, and may independently in each occurrence be alkyl of from 1 to about 12 carbon atoms. In one embodiment, the dialkyl carbonate may be dimethyl carbonate, diethyl carbonate, or a mixture thereof. The amount of alkylene carbonate, dialkyl carbonate or both used in the practice of this invention may vary widely. Typically the total amount of carbonate is from about 0.1 to about 90 percent by weight of the total composition. In one embodiment, the amount is from about 10 to about 50 percent by weight, preferably from about 15 to about 25 percent by weight.
In general, the DBE used in this invention include aliphatic diesters having a molecular weight of up to about 200. DBE has the advantage of being considered to be safe and of low toxicity. More than one dibasic ester can be used in the present compositions. DBE is a well known material and is currently available commercially. In general, the DBE used in this invention may be described as being a C
1
to C
6
dialkyl ester of a C
2
to C
10
aliphatic di-acid, and particularly a C
1
to C
4
dialkyl ester of a C
2
to C
6
aliphatic di-acid. For example, the DBE used in the practice of this invention may be derived from various di-acids such as from adipic acid, glutaric acid and succinic acid.
The amount of DBE used in the practice of this invention may vary widely. In general, the amount of DBE may be from about 0.1 percent by weight to about 90 percent by weight, more typically in the range from about 5 to about 50 percent by weight. In one embodiment of this invention, the DBE is present in an amount in the range from 15 to about 45 percent by weight of the total composition, preferably from about 20 to about 45 percent.
The mono-esters that may employed in the practice of this invention may vary widely. The mono-esters that may be used in the practice of this invention typically contain up to about 20 carbons. The mono-esters may include other functional groups in the compound. For instance, the mono-esters may also include ether groups, such as methyl, propyl or butyl ether groups. Representative non-limiting examples of esters that may be employed in the practice of this invention include ethyl acetate, butyl acetate, ethyl-3-ethoxy-propionate, propylene glycol methyl ether acetate, propylene glycol butyl ether acetate, dipropylene glycol methyl ether acetate and dipropylene glycol butyl ether acetate. Likewise, cyclic esters such as butyrolactone may be employed in the practice of this invention. Preferred mono-esters include an ether group. Ethyl-3-ethoxy-propionate (“EEP”) is a representative preferred mono-ester which is considered to be safe and of low toxicity. The amount of mono-ester used in the practice of this invention may vary widely. Typically the amount is from about 0.1 to about 90 percent by weight of the total composition. In one embodiment, the amount is from about 5 to about 50 percent, preferably from about 15 to about 45 percent, and more preferably from about 20 to about 40 percent.
The organic sulfur-containing compounds that may employed in the practice of this invention may vary widely. The organic sulfur-containing compounds that may be used in the practice of this invention typically contain up to about 20 carbons. The organic sulfur-containing compounds may include other functional groups in the compound. Representative examples of sulfur-containing compounds that may be employed in the practice of this invention include dimethylsulfo
Darragas Katty
Machac, Jr. James R.
Marquis Edward T.
Woodrum Susan A.
Gupta Yogendra N.
Huntsman Petrochemical Corporation
Mruk Brian P.
O'Keefe Egan & Peterman, LLP
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