Alkoxy-substituted perfluorocompounds

Details Alkoxy-substituted perfluorocompounds Alkoxy-substituted perfluorocompounds

2003-01-10

2003-08-19

Boyer, Charles (Department: 1751)

Cleaning compositions for solid surfaces, auxiliary compositions

Cleaning compositions or processes of preparing

Liquid composition

C510S505000

Reexamination Certificate

active

06608019

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to cleaning compositions comprising at least one partially-fluorinated ether compound and to processes for removing contaminants from substrate surfaces using such compositions. In another aspect, this invention relates to certain novel partially-fluorinated ether compounds. In yet another aspect, this invention relates to coating compositions comprising at least one partially-fluorinated ether compound and to processes for depositing coatings on substrate surfaces using such compositions.
BACKGROUND OF THE INVENTION
Solvent cleaning applications where contaminated articles are immersed in (or washed with) solvent liquids and/or vapors are well-known. Applications involving one or more stages of immersion, rinsing, and/or drying are common. Solvents can be used at ambient temperature (often, accompanied by ultrasonic agitation) or at elevated temperatures up to the boiling point of the solvent.
A major concern in solvent cleaning is the tendency (especially where solvent is used at an elevated temperature) for solvent vapor loss from the cleaning system into the atmosphere. Although care is generally exercised to minimize such losses (e.g., through good equipment design and vapor recovery systems), most practical cleaning applications result in some loss of solvent vapor into the atmosphere.
Solvent cleaning processes have traditionally utilized chlorinated solvents (e.g., chlorofluorocarbons such as 1,1,2-trichloro-1,2,2-trifluoroethane and chlorocarbons such as 1,1,1-trichloroethane) alone or in admixture with one or more cosolvents such as aliphatic alcohols or other low molecular weight, polar compounds. Such solvents were initially believed to be environmentally-benign, but have now been linked to ozone depletion. According to the Montreal Protocol and its attendant amendments, production and use of the solvents must be discontinued (see, e.g., P. S. Zurer, “Looming Ban on Production of CFCs, Halons Spurs Switch to Substitutes,” Chemical & Engineering News, page 12, Nov. 15, 1993).
Thus, there has developed a need in the art for substitutes or replacements for the commonly-used cleaning solvents. Such substitutes should have a low ozone depletion potential, should have boiling ranges suitable for a variety of solvent cleaning applications, and should have the ability to dissolve both hydrocarbon-based and fluorocarbon-based soils. Preferably, substitutes will also be low in toxicity, have no flash points (as measured by ASTM D3278-89), have acceptable stability for use in cleaning applications, and have short atmospheric lifetimes and low global warming potentials.
Partially-fluorinated ethers have been suggested as chlorofluorocarbon alternatives (see, e.g., Yamashita et al., International Conference on CFC and BFC (Halons), Shanghai, China, Aug. 7-10, 1994, pages 55-58).
European Patent Publication No. 0 450 855 A2 (Imperial Chemical Industries PLC) describes the use of low molecular weight, fluorine-containing ethers of boiling point 20-120° C. in solvent cleaning applications.
International Patent Publication No. WO 93/11280 (Allied-Signal, Inc.) discloses a non-aqueous cleaning process which utilizes a fluorocarbon-based rinsing solvent.
U.S. Pat. No. 5,275,669 (Van Der Puy et al.) describes hydrofluorocarbon solvents useful for dissolving contaminants or removing contaminants from the surface of a substrate. The solvents have 4 to 7 carbon atoms and have a portion which is fluorocarbon, the remaining portion being hydrocarbon.
U.S. Pat. No. 3,453,333 (Litt et al.) discloses fluorinated ethers containing at least one halogen substituent other than fluorine and states that those ethers which are liquid can be used as solvents for high molecular weight resinous perhalogenated compounds such as solid polychlorotrifluoroethylene resins.
French Patent Publication No. 2,287,432 (Societe Nationale des Poudres et Explosifs) describes new partially-fluorinated ethers and a process for their preparation. The compounds are said to be useful as hypnotic and anesthetic agents; as monomers for preparing heat-stable, fire-resistant, or self-lubricant polymers; and in phyto-sanitary and phyto-pharmaceutical fields.
German Patent Publication No. 1,294,949 (Farbwerke Hoechst AG) describes a technique for the production of perfluoroalkyl-alkyl ethers, said to be useful as narcotics and as intermediates for the preparation of narcotics and polymers.
SUMMARY OF THE INVENTION
In one aspect, this invention provides a process for removing contaminants (e.g., hydrocarbons, fluorocarbons, or even water) from the surface of a substrate (e.g., metal, glass, ceramic, plastic, or fabric). The process comprises contacting the substrate with (or exposing the substrate to) a liquid- and/or vapor-phase cleaning composition comprising at least one mono-, di-, or trialkoxy-substituted perfluoroalkane, perfluorocycloalkane, perfluorocycloalkyl-containing perfluoroalkane, or perfluorocycloalkylene-containing perfluoroalkane compound. The compound can optionally contain additional catenary (i.e., in-chain) heteroatoms (e.g., oxygen or nitrogen) and preferably has a boiling point in the range of from about 25° C. to about 200° C.
The alkoxy-substituted compounds used in the process of the invention exhibit unexpectedly high stabilities in the presence of acids, bases, and oxidizing agents. In addition, in spite of their fluorine content, the compounds are surprisingly good solvents for hydrocarbons (as well as fluorocarbons). The compounds are low in toxicity and flammability, have ozone depletion potentials of zero, and have short atmospheric lifetimes and low global warming potentials relative to chlorofluorocarbons and many chlorofluorocarbon substitutes. Since the compounds exhibit good solvency properties while being environmentally acceptable, they satisfy the need in the art for substitutes or replacements for the commonly-used cleaning solvents which have been linked to the destruction of the earth's ozone layer.
In other aspects, this invention also provides certain novel mono-, di-, and trialkoxy-substituted perfluorocompounds; a cleaning composition; a coating composition; and a process for depositing coatings (e.g., coatings of lubricant) on substrate surfaces.
DETAILED DESCRIPTION OF THE INVENTION
Compounds which can be utilized in the processes of the invention are mono-, di-, or trialkoxy-substituted perfluoroalkane, perfluorocycloalkane, perfluorocycloalkyl-containing perfluoroalkane, and perfluorocycloalkylene-containing perfluoroalkane compounds. The compounds include those which contain additional catenary heteroatoms (as well as those which do not) and can be utilized alone, in combination with one another, or in combination with other common cleaning solvents (e.g., alcohols, ethers, alkanes, alkenes, perfluorocarbons, perfluorinated tertiary amines, perfluoroethers, cycloalkanes, esters, ketones, aromatics, siloxanes, hydrochlorocarbons, hydrochlorofluorocarbons, and hydrofluorocarbons). The compounds can be solids or liquids under ambient conditions of temperature and pressure, but are generally utilized for cleaning in either the liquid or the vapor state (or both). Thus, normally solid compounds can be utilized after tranformation to liquid and/or vapor through melting, sublimation, or dissolution in liquid co-solvent.
A class of useful alkoxy-substituted perfluorocompounds is that which can be represented by the following general formula (I):
R
f
—(O—R
h
)
x
  (I)
wherein x is an integer of 1 to 3; when x is 1, R
f
is selected from the group consisting of linear or branched perfluoroalkyl groups having from 2 to about 15 carbon atoms, perfluorocycloalkyl-containing perfluoroalkyl groups having from 5 to about 15 carbon atoms, and perfluorocycloalkyl groups having from 3 to about 12 carbon atoms; when x is 2, R
f
is selected from the group consisting of linear or branched perfluoroalkanediyl groups or perfluoroalkylidene groups having from 2 to about 15 carbon atoms, perfluorocycloalkyl- or perfluorocycloalkylene-conta

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