(4PR) unsaturated polyester Resins are the basis raw materials forthe manufacture of general purpose (GP) products which has applications inalmost every field of operation such as transport, construction, civil, marine,chemicals, electrical, engineering as well as domestic applications.
CommercialUPR resins are composed of the following essential ingredients a Linearpolyester resin, a cross linking monomer and inhibitor to retard cross linkinguntil the resin is to be used by the fabricator. The linear polyester is typically thecondensation product of an unsaturated dibasic acid as the source of ethylenicunsaturation and a glycol; the usual cross linking monomer are styrene, vinyltolerance, methyl methacrylate, conventional inhibitors are hydroquinone,t-butyl catechol. The basis resin can bepolymerized to infusible materials by the action of free radicals such as peroxides.
Processof manufacture : There is a two step batchprocess, i) Condensatioin reaction between a dibasic acid and a diol in aninert gas atmosphere until a low acid number is reached. The resulting linear co-polymer is cooked andblended with a monomer usually at 1200-1500- (6000C-6500C)and an inhibitor to impart storage stability.