Bisphenol A diglycidyl ether (commonly abbreviatedBADGE orDGEBA) is anorganic compound and is a liquidepoxy resin.[1][2][3][4][5] The compound is a colorless viscous liquid (commercial samples can appear pale straw-coloured).[6][7] It is a key component of many epoxy resin formulations. Addition of further Bisphenol A and a catalyst and heat can produce Bisphenol A glycidyl ether epoxy resins of higher molecular weight that are solid.[8]
Structure of bisphenol-A diglycidyl ether epoxy resin:n denotes the number of polymerized subunits and is typically in the range from 0 to 25
It is prepared by O-alkylation ofbisphenol A withepichlorohydrin. This reaction mainly affords bisphenol A diglycidyl ether, as well as someoligomer. Thedegree of polymerization may be as low as 0.1.[9] The epoxide content of such epoxy resins is of interest. This parameter is commonly expressed as theepoxide number, which is the number of epoxide equivalents in 1 kg of resin (Eq./kg), or as the equivalent weight, which is the weight in grams of resin containing 1 mole equivalent of epoxide (g/mol). Since unsymmetrical epoxides arechiral, the bis epoxide consists of threestereoisomers, although these are not separated.
Similarly, DGEBA reacts with acrylic acid to givevinyl ester resins. The reaction results in opening of the epoxide ring, generating unsaturated esters at each terminus of the molecule. Such materials are often diluted with styrene and converted to resin.
Epoxy resins arethermosetting polymers, which are crosslinked using hardeners (curing agents). The most common curing agents for epoxy resins arepolyamines, aminoamides, and phenolic compounds.[10]
BADGE is highly reactive and forms a number of species upon exposure to water or HCl and many of these compounds (including BADGE) are suspectedendocrine disruptors.[11] Hydrolysis of theether bonds liberates bisphenol A, which is also strongly suspected of being an endocrine disruptor.[12][13] From the 1990s onward, concern has been raised over the use of BADGE-based epoxy resins in the lining of some cans for foodstuffs, with the chemical being found to leach into foods.[12][14] Bisphenol A Diglycidyl ether-based epoxy coatings are extensively used for coating the inside of cans which come into contact with food and are thusfood contact materials. The materials and analogues and conjugates have been extensively tested for and analytical methods developed.[15][16]
