Epoxy resins commercial manufacture

Similar to all commercial plastics, the traditional and more commonly used thermosetting resins are considered as petrochemicals, having been manufactured from petroleum. Some of the primary distillation products of crude oil, which can be classified either as olefins or aromatics, serve as precursors for the synthesis of thermosets. For example, epoxy resins are manufactured by the reaction of epichlorohydrin, a chloro-oxirane, and a derivative of propylene, with bisphenol A, which is a derivative of cumene. Another example would be the unsaturated polyesters (UPs), which are derivatives ultimately originating from ethylene (ethylene glycol) and benzene (maleic acid) [6]. Epoxies and polyesters constitute more than 95% of the thermoset composite market of the two, polyester-based systems predominate in volume by about 10-fold [6, 7]. Other thermoset resins used in reinforced form are phenolics, vinyl esters, and polyimides. Details of the properties and applications of these thermoset systems will be further discussed in the following section. 

In the preparation of commercial DGEBPA, an excess of epichl orohydrin is used in order to minimize polymeriza tion of the reactants to higher molecular-weight species. Nevertheless, the typical viscous final product usually contains ca 80% by weight of the monomeric (n = 0) DGEBPA as deterrnined by gel-permeation chromatography (gpc). The manufacture of Hquid epoxy resins in a batch process has been described in some detail (9). 

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. 

Ally Acetate can be a starting material for polymers as a comonomer, for glycidyl acetate as a component of epoxy resins, for glycerol, for allyl alcohol by hydrolysis, and for the synthesis of allyl esters of higher acids or other compounds by transesterification or transallylation. Processes for the commercial production of allyl acetate have been developed by Bayer and Hoechst [60], and some Japanese companies. Such processes work in the gas-phase under similar conditions to those used in vinyl acetate manufacture and are currently operated by Showa Denko and Daicel [61]. 

Epichlorohydrin or chloromethyloxirane is manufactured from allyl chloride, and, in 2006, had a merchant price of US 1.66 kg [4]. It is used as a building block in the manufacture of plastics, epoxy resins, phenoxy resins, and other polymers, and as a solvent for cellulose, resins, and paints, and has also found use as an insect fumigant. Epoxy resins (aryl glycidyl ethers) are manufactured successfully in large scale (1.2 x 10 metric tons in 2000) [26] and are widely used in a variety of industrial and commercial applications [27]. These are made by addition reactions of epichlorohydrins or by epoxidation of allyl ethers or esters (Table 1.1). Epichlorohydrin can be reacted with an alkali nitrate to produce glycidyl nitrate, an energetic binder used in explosive and propellant compositions. 

Other epoxy resins are also being manufactured, but their commercial j utilization is not so far advanced as those based on bisphenol A and i epichlorohydrin. For instance, resorcinol and a mixture of diphenol-poly-(hydroxyphenyl)-pentadecanes, obtained by the addition reaction of phenol with an unsaturated phenol derived from cashew-nut oil (see structure below) can be reacted with epichlorohydrin to produce epoxy resins. ... 

Epichlorhydrin which is used for the synthesis of epoxy resins is a suspected carcinogen in animals. Thanks to the well developed manufacturing processes, practically all the current commercially available epoxy resins contain only the smallest traces of epichlorhydrin (Occupational Hygiene Advices for Manufacturing and Processing Plastics of CIBA, Company brochure). 

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