The present invention is directed to cleaning agent compositions, especially useful in the electronics industry, containing acyclic aliphatic hydrofluorocarbons and a co-solvent.
Various organic solvents have been used as cleaning liquids for the removal of contaminants from articles and materials. Certain chlorofluorocarbons such as 1,1,2-trichloro-1,2,2-trifluoroethane have been reported as useful for this purpose, particularly with regard to cleaning organic polymers and plastics which may be sensitive to other more common and more powerful solvents such as trichloroethylene or perchloroethylene.
Solvent cleaning and degreasing with chlorofluorocarbon-based solvents have been used extensively in industry for cleaning solid surfaces, particularly the surfaces of intricate parts. Common uses include the removal of fluxes from circuit boards and removing oils, grease and abrasives from machine parts. Cleaning procedures include exposing the cool article to vapors of the boiling chlorofluorocarbon cleaning composition and allowing any chlorofluorocarbon to evaporate from the cleaned article. Another cleaning technique involves immersing the article to be cleaned in a sump of boiling chlorofluorocarbon cleaning composition which removes most of the soil from the article, followed by a second immersion of the article in fresh chlorofluorocarbon at about room temperature and finally exposing the cooled article to vapors over the boiling sump. However, hydrofluorocarbons used alone are not effective cleaning agents.
Recently, the long term environmental effects of chlorofluorocarbons have come under scientific scrutiny because it has been postulated that these materials because of their high stability are able to reach the stratosphere where under the influence of ultraviolet radiation release chlorine atoms which, in turn, undergo chemical reaction with stratospheric ozone. Reduction of the stratospheric ozone layer would increase the amount of ultraviolet radiation reaching the earth's surfaces. In view of the potential environmental problems associated with stratospheric ozone depletion, there is a need for new materials possessing properties which make them useful substitutes for applications in which chlorofluorocarbons have been used.
Accordingly, there is a need in the industry for effective cleaning agents for removing oils, grease and abrasives, fluxes, water, etc., which are nonflammable, possess low toxicity and are degradable in the lower atmosphere.