CFC solvents

There now exist alternatives or sufficient quantities of controlled substances for almost all applications of ozone-depleting solvents. Exceptions have been noted for certain laboratory and analytical uses and for manufacture of space shuttle rocket motors. HCFCs have not been adopted on a large scale as alternatives to CFC solvents. In the near term, however, they may be needed as the conventional substances in some limited and unique applications. HCFC-141b is not a good replacement for methyl chloroform (1,1,1 -trichloroethane) because its ODP is three times higher. Alternatives for specific uses of ozone-depleting solvents are briefly described below. 

Polymerization. Since fluorinated products are SCCO2 -philic, CO2 can be used as a substitute for CFC solvents in the production of fluoropolymers.5-7,38,39 Selection of fluorosurfactants has enabled polymerization of SCCO2-phobic polymers such as polymethyl methacrylate. " "" ... 

Fluoropolymers could not be prepared in hydrocarbon solvents and earlier routes to them had employed ozone-depleting chlorofluorocarbon (CFC) solvents. The C02-philic nature of both the monomers and the resulting polymers allowed a homogeneous polymerization reaction to be performed. DuPont now... 

Aqueous Cleanable. All parts should preferably be cleanable in water or a safe solvent, unless they come out of the production process clean enough to be double-bagged and shipped directly to the clean-room assembly area. When soldering is involved, for example, the specification should call out for the use of water-soluble or noclean fluxes. Parts and assembly design should allow suppliers to quickly switch to a non-CFC solvent. 

Even though the CFC materials will be around for a number of years in recycled form, there are a number of non-CFC-containing solvent systems that are being used or are under consideration as alternatives to CFC cleaners. One desirable aspect of using CFC solvents is their non-corrosive nature. Many of the proposed replacements for the CFCs are much more aggressive. An interim replacement for the CFCs could be the HCFCs, which have a lower ozone depletion factor, but these will also be phased out in the near future. Information on CFC replacements can be obtained from the EPA s Ozone Information Hotline (see www.epa.gov). 

Chlorinated solvents (cleaning) Solvents containing carbon and chlorine, such as trichloroethylene (TCE), methylene chloride (MEC), Perchloroethylene (PERC), and 1,1,1 trichloroethane (TCA). Very effective solvents but regulated because of health and environmental concerns. Example Carbon tetrachloride (CCI4), a fully chlorinated solvent. See also Chlorofluorocarbon (CFC) solvents Hydrochlorofluorocarbon (HCFC) solvents. 

Hydrochlorofluorocarbon (HCFC) solvent (cleaning) A solvent containing hydrogen as well as chlorine and fluorine. Examples HCFC-22 (CHCIF2) HCFC-124 (CHCIFCF3). See also Chlorinated solvents Chlorofluorocarbon (CFC) solvents. 

HALIDES Carbon tetrachloride Chlorofluorocarbons CFCs Solvent Propellants for aerosols... 

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