Trichloroethylene, solvent cleaning

Many chlorinated hydrocarbons react readily with aluminum in the so-caHed bleeding reaction. A red aluminum chloride—chlorinated hydrocarbon complex is formed. Storage of uninhibited chlorinated solvents in aluminum vessels results in corrosion in a short period of time. Proprietary organic inhibitors permit commercial use of reactive solvents such as 1,1,1-trichloroethane and trichloroethylene for cleaning of aluminum. 

Trichloroethylene Solvents, dry-cleaned fabrics, printing inks, paints, varnishes, adhesives, fax machines, computer terminals and printers, correction pen fluids, paint removers, spot removers. 28 2A... 

Tri-n-octyl phosphate Trioxane n-Undecane Vinyltoluene monomer m-Xylene 2,5-Xylenol 2,6-Xylenol solvent cleaning Dodoxynol-7 solvent drying Trichlorotrifluoroethane solvent dyeing Trichloroethylene solvent extraction Ethylamine... 

Enclosed vapor degreasers have become popular and necessary in the last two decades (Box 2.1). The reason is that non-solvent cleaning methods (particularly aqueous cleaning technology) don t provide adequate performance, and some users desire or need to use solvents about which there are SHE (safety, health, and environmental) concerns — particularly perchloroethylene, methylene chloride, trichloroethylene, and n-propyl bromide (in that order). 

These steps are enumerated and described in Chapter 1.2. Operation of superheat in open-top vapor degreasers is explained in Chapter 1.20 For reference, solvent cleaning operations with trichloroethylene and n-propyl bromide are conducted at their boiling points - 86°C (187"F) and 71"C (160°F), respectively. It is this author s experience that Class II cosolvent processes have found more interest in Europe than in the US. The chief application is removal of flux residues from printed wire boards (PWBs). 

The simplest treatment is solvent cleaning [33], and the effect of dipping a polypropylene substrate into a trichloroethylene solvent vapour prior to bonding to aluminium using an epoxy adhesive is shown in Fig. 4.4. The effect of a short exposure time on the joint strength is spectacular but overtreatment... 

Solvent cleaning can leave a surface layer of residue that must be removed. This removal can involve either water rinsing, other solvents that displace the surface layer, or an elevated temperature. For instance, a solvent wipeclean cleaning sequence might be trichloroethylene (TCE), acetone, methanol, isopropanol. 

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. 

AH volatile organic solvents are toxic to some degree. Excessive vapor inhalation of the volatile chloriaated solveats, and the central nervous system depression that results, is the greatest hazard for iadustrial use of these solvents. Proper protective equipment and operating procedures permit safe use of solvents such as methylene chloride, 1,1,1-trichloroethane, trichloroethylene, and tetrachloroethylene ia both cold and hot metal-cleaning operations. The toxicity of a solvent cannot be predicted from its chlorine content or chemical stmcture. For example, 1,1,1-trichloroethane is one of the least toxic metal-cleaning solvents and has a recommended threshold limit value (TLV) of 350 ppm. However, the 1,1,2-trichloroethane isomer is one of the more toxic chloriaated hydrocarboas, with a TLV of only 10 ppm. 

Tetrachloroethylene was first prepared ia 1821 by Faraday by thermal decomposition of hexachloroethane. Tetrachloroethylene is typically produced as a coproduct with either trichloroethylene or carbon tetrachloride from hydrocarbons, partially chloriaated hydrocarbons, and chlorine. Although production of tetrachloroethylene and trichloroethylene from acetylene was once the dominant process, it is now obsolete because of the high cost of acetylene. Demand for tetrachloroethylene peaked ia the 1980s. The decline ia demand can be attributed to use of tighter equipment and solvent recovery ia the dry-cleaning and metal cleaning iadustries and the phaseout of CFG 113 (trichlorotrifluoroethane) under the Montreal Protocol. 

Trichloroethylene is a colourless non-flammable chlorinated hydrocarbon liquid. It is mainly used for degreasing of metals in the engineering and electrical appliance industries other outlets are as a solvent in inks, in dry-cleaning, in varnishes and adhesives, and as a solvent in the extraction of fats and oils. Relevant physical properties are given in Table 5.51. 

Common gases such as oxides of carbon and nitrogen, hydrogen sulphide, and inert gases. Liquids which pose a health hazard due to volatilization, e.g. mercury and degreasing with chlorinated solvent, i.e. dry cleaning with perchloroethylene or metal cleaning with trichloroethylene. 

Organic solvents inhaled by abusers include gasoline, glue, aerosols, amyl nitrite, butyl nitrite, typewriter correction fluid, lighter fluid, cleaning fluids, paint products, nail polish remover, waxes, and varnishes. Chemicals in these products include nitrous oxide, toluene, benzene, methanol, methylene chloride, acetone, methyl ethyl ketone, methyl butyl ketone, trichloroethylene, and trichloroethane. 

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