Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
2000-11-28
2002-04-09
Boyer, Charles (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
C510S202000, C510S206000, C510S211000, C510S405000, C510S432000, C134S038000
Reexamination Certificate
active
06369009
ABSTRACT:
BACKGROUND OF INVENTION
This invention relates to compositions for paint and coating removal. More particularly, this invention relates to compositions containing alkylene carbonate or dialkyl carbonate or both, hydrogen peroxide, and water.
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
In one broad respect, this invention is a composition useful as a paint remover, comprising: alkylene carbonate, hydrogen peroxide, and water. This composition may also contain dibasic ester.
In another broad respect, this invention is a process for removing paint, comprising: applying a composition containing alkylene carbonate, hydrogen peroxide, and water to a painted surface for a time and under conditions effective to cause blistering or bubbling of the paint. The composition used therein may also contain dibasic ester.
In another broad respect, this invention is a process for removing paint, comprising: applying a composition containing (a) alkylene carbonate, dialkyl carbonate, or both, (b) hydrogen peroxide, and (c) water to a painted surface for a time and under conditions effective to cause blistering or bubbling of the paint. The composition used therein may also contain dibasic ester.
In another broad respect, this invention is a composition useful as a paint remover, comprising: dialkyl carbonate, hydrogen peroxide, and water. This composition may optionally contain an alcohol, a glycol ether, an alkylene carbonate, or a combination thereof This composition may instead include dibasic ester.
In another broad respect, this invention is a process for removing paint, comprising: applying a composition containing dialkyl carbonate, hydrogen peroxide, and water to a painted surface for a time and under conditions effective to cause blistering or bubbling of the paint. The composition used therein may also contain dibasic ester.
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, and neutral pH (or slightly acidic or slightly basic pH). Furthermore, in the case of propylene carbonate, the propylene carbonate breaks down into propylene glycol, which is non-toxic. Likewise, hydrogen peroxide decomposes over time to water. 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. In addition, the compositions of this invention cause blistering and bubbling in such a short period of time that it is envisioned that the compositions of this invention might be applied in liquid form, as opposed to the gels which are commonly applied which lesson evaporation of the chlorinated hydrocarbons, for example.
It has further been advantageously found that by employing hydrogen peroxide in the form of an at least 50% aqueous solution, a miscible solution forms with alkylene carbonate. In the context of this invention, by miscible solution it is meant a single phase solution. The resulting composition has surprisingly superior paint removing properties, which is believed to be due to the limited amount of water present. The compositions may be blended with additional cosolvents, activators, corrosion inhibitors, and the like, or may be used directly to effect paint removal. The compositions of this invention may advantageously be non-flammable, of low volatility and free of carcinogenic chemicals.
DETAILED DESCRIPTION OF THE INVENTION
The compositions of this invention contain alkylene carbonate or dialkyl carbonate or both, hydrogen peroxide, and water.
The hydrogen peroxide and water can be conveniently obtained from commercial sources as aqueous hydrogen peroxide solutions of varying percentages. Hydrogen peroxide is commonly available in aqueous solutions at a concentration of from about 1 to about 80 percent. For example, industrial solutions are often 30 percent or more by weight hydrogen peroxide solutions. It has been found that in the practice of this invention, the use of a 50% aqueous hydrogen peroxide solution is particularly effective. It may be appreciated that highly concentrated hydrogen peroxide should be handled carefully and appropriately since such materials are considered strong oxidizers. It may also be noted that once the concentrated hydrogen peroxide solution is admixed with carbonate, the concentration of hydrogen peroxide decreases which thus reduces the hazardous nature of the final composition. For example, when the overall concentration of hydrogen peroxide in the admixed composition is less than about 30%, special precautions need not be taken to handle the composition. Use of an aqueous hydrogen peroxide solution having a concentration of from about 30% to about 50% is preferred in the practice of this invention, with a concentration of about 50% providing a superior balance of paint stripping ability and miscibility with carbonate. In this regard, it should be appreciated that a lower hydrogen peroxide concentration of the aqueous solution may require use of cosolvents, surfactants, or the like to provide a miscible final composition.
In one embodiment of this invention, the amount of hydrogen peroxide in the total composition is at least 4 percent by weight. In another embodiment, the amount of hydrogen peroxide in the total composition is at least 10 percent by weight. In another embodiment of this invention, the amount of hydrogen peroxide is at least 15 percent by weight of the total composition or, alternatively, at least 35 percent by weight.
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. In the practice of this invention, 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.
Concentrated solutions would range from about 8 to about 15 percent peroxide with the balance being water and dialkyl carbonate or dialkyl carbonate and alkylene carbonate.
The compositions of this invention may optionally include an alcohol. Representative examples of such alcohols include methanol, ethanol, propanol, butanol, and benzyl alcohol. In the practice of this invention, benzyl alcohol is preferred. Generally, compositions of this invention contain from 0 to about 90 percent by weight alcohol. For the removal of certain types of coatings, it has been found the efficiency of the carbonate hydrogen deoxidized water solution may be improved by the addition of an alcohol.
The compositions of this invention may include an ether ester. The ether esters that may employed in the practice of this invention may vary widely, and typically contain up to abo
Machac, Jr. James R.
Marquis Edward T.
Woodrum Susan A.
Boyer Charles
Huntsman Petrochemical Corporation
O'Keefe Egan & Peterman, LLP
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