Applications epichlorohydrin

Applications. Epichlorohydrin elastomers have good low-temperature flexibility, a broad range of temperature utilization, outstanding resistance to ozone, air and heat aging, high resistance to a variety of fuels, and good chemical resistance. Therefore, they have found applications particularly in the automotive industry and in many oil-field specialities. 

The rubbers may be vulcanised by conventional accelerated sulphur systems and also by peroxides. The vulcanisates are widely used in petrol hose and seal applications. Two limiting factors of the materials as rubbers are the tendency to harden in the presence of sulphur-bearing oils, particularly at elevated temperatures (presumably due to a form of vulcanisation), and the rather limited heat resistance. The latter may be improved somewhat by Judicious compounding to give vulcanisates that may be used up to 150°C. When for the above reasons nitrile rubbers are unsatisfactory it may be necessary to consider acrylic rubbers (Chapter 15), epichlorohydrin rubbers (Chapter 19) and in more extreme conditions fluororubbers (Chapter 13). 

Epoxytin compounds are obtained by either hydrostannylation of unsaturated epoxides or condensation of organotin alcohols with epichlorohydrin 70). Extensive applications of these compounds in plastic industry have been suggested. 

Thioureas mainly find use for the vulcanisation of CR, epichlorohydrin (ECO) and some ethylene propylene diene terpolymer (EPDM) compounds. They show high crosslinking activity, with usually adequate compound flow time before onset of the crosslinking. In EPDMs, the thioureas are used as activators for low activity third monomer types and, in the presence of calcium oxide desiccants, in free state vulcanisation of extrudates, etc. The use of thioureas can overcome the retardation caused by the desiccant. In this case some care must be taken otherwise overcompensation may occur. Thioureas are not used in food product applications and are a known health hazard, particularly for pregnant women. 

The development and optimisation is described of a new curing system to replace lead-based compounds used in epichlorohydrin elastomers currently used in automotive applications. The system is based on 2,4,6-trimercapto-1,3,5-triazine and dialkyldithiophosphate, which is shown to produce a scorch-safe curing system and which confers excellent physical and ageing properties on epichlorohydrin rubbers. Trials are conducted in formulations for multilayer fuel hoses. 9 refs. 

Many other crosslinking reactions are used in commercial applications. A variety of halogen-containing elastomers are crosslinked by heating with a basic oxide (e.g., MgO or ZnO) and a primary diamine [Labana, 1986 Schmiegel, 1979]. This includes poly(epichlorohydrin) (Sec. 7-2b-6) various co- and terpolymers of fluorinated monomers such as vinylidene fluoride, hexafluoropropene, perfluoro(methyl vinyl ether), and tetrafluoroethylene (Sec. 6-8e) and terpolymers of alkyl acrylate, acrylonitrile, and 2-chloroethyl vinyl ether (Sec. 6-8e). 

The principal uses of ECO are in automotive applications, eg, for fuel line and fuel vapor recirculation. There are also some downhole seal applications where ECO is used. About 7000 t/yr of epichlorohydrin are used in the United States. This is all supplied by the Zeon Corporation. 

Epichlorohydrin was tested in rats by oral administration, inducing papillomas and carcinomas of the forestomach, and by inhalation, inducing papillomas and carcinomas of the nasal cavity. It was also tested in mice by skin application and by subcutaneous and intraperitoneal injection it gave negative results after continuous skin painting but was active as an initiator on skin. It produced local sarcomas after subcutaneous injection and was active in a mouse-lung tumour bioassay by intraperitoneal injection. 

Stephenson has developed a convenient procedure for preparing J-chloro-3-phenoxy-2-propanols from epichlorohydrin nnd phenols, which is economical of reagents and minimizes the formation of undesirable side-products (Eq. 600). He has also greatly extended the applicability of hydrogen chloride transfer for the preparation of epoxides. ... 

The graft polymerization process also applies to other backbone polymers, such as rubbery ethylene-propylene copolymers and amorphous epichlorohydrin polymers. Further work is necessary to bring the resulting products to industrial maturity and to develop their applications. 

Liquid resins containing bromine (ca 49 wt %) can also be prepared directly from tetrabromobisphenol A and epichlorohydrin and are used for critical applications where a high degree of flame retardancy is required. 

Fastness Improvement. The wetfastnesses of dyeings on wool that has been chlorinated to prevent felting and has received a finish with synthetic resin (poly-amide-epichlorohydrin or polyurethane superwash wool) can be increased by means of methylol amide compounds. Both fastness and antifelting finish can be improved through the application of a polyquatemary compound [88]. Anionic condensation products such as aromatic sulfonic acids with formaldehyde can form a barrier at the surface of the fiber and thus diminish the bleeding of anionic dyes. 

The new applications are to be found outside the traditional commercial applications of glycerol in food additives, pharmaceuticals, cosmetics and personal care products and also various industrial applications, such as the synthesis of polyethers, polyols and alkyd resins, detergents, explosives, etc. [85]. The use of low-quality glycerol from biodiesel production for these applications is often avoided, however. Additional fields of applications as a C3 building block have been widely investigated and in a few cases even commercialized, e.g. the production of epichlorohydrin via the EPICEROL process of Solvay Chemicals. 

LPEI was also used to prepare interpolymers with poly(epichlorohydrin) for membrane applications [23]. 

Epoxy resin can have varying amounts of inorganic material remaining in the product after its synthesis. One of these is sodium chloride, which is formed by the reaction of sodium hydroxide with epichlorohydrin molecules, as described in Chap. 2. This is important in electrical applications because the sodium salt can be hydrolyzed and can degrade electrical properties. Some epoxy resin manufacturers will offer special ultrapure electrical grades or low-chlorine grades of epoxy resins for application where this is an important factor. 

Brominated epoxy resins are the reaction product of epichlorohydrin and brominated bisphenol A. They are primarily used in applications where ignition resistance is a requirement, such as printed-circuit boards and other products that need to be flame-retardant. Tetrabromobisphenol A is the largest flame retardant in terms of commercial use at present. It is used in an estimated 95 percent of all flame-retardant printed wiring boards and is used in many flame-retardant surface-mounted adhesives.2 It is manufactured by several producers and is priced as a commodity product. 

The in situ generation of performic and peracetic acids has an important application in producing epoxidized soya bean oil (ESBO), a plasticizer and stabilizer. The acetic acid is often re-cycled. Technology for the manufacture of propylene oxide98 and of epichlorohydrin" using internal cycle systems for peracetic or perpropionic acids has also been developed. 

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