Epoxy oligomer reactive groups

Epoxy acrylates are dominant oligomers in the radiation curable adhesives market. A bisphenol A epoxy resin is reacted with acrylic acid or methacrylate acid to provide unsaturated terminal reactive groups. The acrylic acid-epoxy reaction to make bisphenol A diacrylate destroys any free ingredients such as epichlorohydrin used to make the DGEBA epoxy starting raw material. 

Small molecule epoxides, and some epoxy oligomers also are used as reactive diluents, mixing them with other polymers for crosslinking purposes. An example of epoxide used as curing additive is poly(limonene dioxide) or poly[1-methyl-4-(2-methyloxiranyl)-7-oxabicyclo[4.1.0]heptane], CAS 29616-43-1. This compound can form ether bonds upon heating or by photoinduction in the presence of aryl substituted sulfonium salts. Poly(dicyclopentadiene dioxide), CAS 29987-76-6, has similar properties. The idealized structure of the two monomers with the intact epoxy groups are shown below ... 

The phase separation in systems based on the high-molecular weight compounds is known to occur not only due to alteration of composition, temperature or pressure but also as a result of chemical reaction [19]. In the course of curing of these epoxy oligomers (containing two or more reactive groups) two crosslinked polymers are... 

This procedure can also be used for prepolymers possessing other reactive groups, such as mercapto, chloromethyl, bromomethyl epoxy, amino, aziridine, vinyl, carboxyl, hydroxy or alkoxymethyl groups. Oligomer emulsions can also be obtained by mixing water into the dissolved or liquid ionomer, because these products are inert with respect to water. 

Uncured resins are oligomers of relatively low molecular weight that may be a liquid or a solid. Before epoxy resins can become useful products, they must be cured, with the addition of a curing agent. Curing involves the cross-linkage by polymerization of the reactive epoxy groups into a three-dimensional matrix. 

While they are called resins, they are really monomers to low-molecular-weight oligomers, liquids to soluble fusible solids, with high reactivity in the epoxy rings, and fair reactivity in the internal hydroxyl groups. They are cured most often by room-temperature reaction with polyamines or polyamide amines. 

Tetrabromobisphenol A (TBBPA) is primarily used as a reactive flame retardant in epoxy resin circuit boards. Both hydroxyl groups on TBBPA can be reacted with epichlorohydrin under basic conditions to form the diglycidyl ether, which is widely used in epoxy resin formulations. TBBPA is also used in polycarbonate and ether polyester resins and is used as a chemical intermediate for the synthesis of tetrabromobisphenol A allyl ether, -bis(2-hydroxyethyl ether), -carbonate oligomer, and -diglycidyl ether. TBBA is also used as a flame retardant in plastics, paper, and textiles, and as a plasticizer in adhesives and coatings. 

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