Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
1999-05-20
2001-03-13
Ogden, Necholus (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
C510S245000, C510S253000, C510S505000, C134S002000, C134S038000, C134S040000
Reexamination Certificate
active
06200945
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to solvent compositions and particularly to environmentally safe solvent compositions for cleaning metal and non-metal surfaces.
BACKGROUND OF THE INVENTION
In industry generally, there is a continuing need to produce compounds that are environmentally safe. The U.S. Environmental Protection Agency (EPA) is concerned with reducing the use of toxic chemicals that the EPA considers to be unsafe environmentally. In particular, in association with their 33/50 Program, the EPA has placed a high priority on reducing the presence of 17 toxic chemicals in the environment. These chemicals are published in a list (“the EPA 17 Toxics list”) that includes benzene, cadmium and cadmium compounds, carbon tetrachloride, chloroform, chromium and chromium compounds, cyanides, lead and lead compounds, mercury and mercury compounds, methyl ethyl ketone, methyl isobutyl ketone, methylene chloride, nickel and nickel compounds, tetrachloroethylene, toluene, trichloroethylene, trichloroethane and xylenes.
One area where the use of environmentally safe compounds is important is the solvent industry. At one time, the preferred cleaning solvent for the aircraft and aerospace industry was methylene chloride. However, for environmental reasons, it has become less desirable for use in solvent compositions. One replacement for methylene chloride has been 1,1,1-trichloroethane (methyl chloroform). But, like methylene chloride, 1,1,1-trichloroethane is not considered environmentally safe. Moreover, 1,1,1-trichloroethane is not as effective a solvent as methylene chloride.
There has been a need in the art to provide new cleaning solvents that are not only effective but also environmentally safe. In the aircraft and aerospace industry recently, the solvents used to clean composites, metal aircraft parts and tooling include methyl ethyl ketone (MEK), toluene, methyl isobutyl ketone (MIBK), and combinations thereof. However, like methylene chloride and 1,1,1-trichloroethane, these compounds are not considered environmentally safe and have been listed on the EPA 17 Toxics list. In addition, the use of toluene must be reported under California law because of its reproductive toxicity. Therefore, there is a need in the art to produce solvent compositions with increased environmental safety that are effective at cleaning metal and non-metal surfaces.
SUMMARY OF THE INVENTION
The present invention provides a solvent composition that is environmentally safe and effective as a cleaning solvent. The solvent composition of the invention is substantially free of chemicals such as methylene chloride, 1,1,1-trichloroethene, MEK, and toluene that are on the EPA 17 Toxics list, includes less than 3% MIBK by volume. Thus the solvent composition is safer for the environment than conventional solvents. In addition to the environmental benefits of the solvent composition of the invention, the solvent composition has a more palatable odor than conventional solvent compositions. The solvent composition of the invention can also effectively be used for various types of metal and non-metal surfaces such as vehicular surfaces. Moreover, the solvent composition can be used in other applications such as a thinning agent for coatings, adhesives, sealants, primers, topcoats, and the like.
The solvent composition of the invention comprises a mixture of methyl propyl ketone (MPK), acetone, isopropyl alcohol and n-butyl acetate and has a calculated vapor pressure below 35 mm Hg at 20° C. Preferably, the vapor pressure is less than about 32 mm Hg at 20° C. (e.g. between about 30 and 32 mm Hg at 20° C.). In one preferred embodiment, the solvent composition includes about 30 to about 33 percent by volume acetone, about 47.5 to about 55 percent by volume methyl propyl ketone, about 10 to about 11 percent by volume isopropyl alcohol, and about 5 to about 6 percent by volume n-butyl acetate. More preferably, the solvent composition of the invention includes about 31 to about 32 percent by volume acetone, about 48.9 to about 53.5 percent by volume methyl propyl ketone, about 10 to about 11 percent by volume isopropyl alcohol, and about 5 to about 6 percent by volume n-butyl acetate. In one example in accordance with the invention, the solvent composition consists of about 31.6 percent by volume acetone, about 49.9 to about 52.6 percent by volume methyl propyl ketone, about 10.5 percent by volume isopropyl alcohol, and about 5.3 percent by volume n-butyl acetate.
In accordance with the invention, the solvent composition is substantially free of chemicals such as methylene chloride, 1,1,1-trichloroethane, MEK and toluene that are on the EPA 17 Toxics list and includes less than 3% MIBK by volume. In addition, the solvents used in the solvent composition of the invention are not listed among the 500 chemicals on the EPA Toxic Release Inventory List. The solvent composition of the invention can be used for cleaning metal and non-metal surfaces or as a thinning agent for coatings, adhesives, sealants, primers, topcoats, and the like.
The present invention also includes a method of cleaning a metal or non-metal surface that includes applying the solvent compositions described herein to a surface and removing the solvent from the surface. In particular, the solvent composition can be used as a cleaning solvent for vehicular surfaces such as for aircraft and automobiles. The present invention also further includes a method of thinning a composition by adding the solvent composition described herein to the composition to be thinned.
These and other features and advantages of the present invention will become more readily apparent to those skilled in the art upon consideration of the following detailed description, which describes both the preferred and alternative embodiments of the present invention.
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Alternative Cleaning Practices,EPA/ICOLP Aircraft Maintenance Manual, pp. 71-188 and Appendix A1-F1.
Lally Edward D.
Menke Richard J.
Alston & Bird LLP
McDonnell Douglas Corporation
Ogden Necholus
Webb Gregory E.
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