Polycarbonates
The term polycarbonate refers to polymers with functional groups linked together by carbonate groups in a long molecular chain. Compared to most other plastics, polycarbonates offer incredible strength, exceptional durability, excellent transparency and light weight – one-sixth as heavy as glass – properties that position these materials between commodity and engineered plastics.
The list of polycarbonate applications is virtually endless: compact discs (CDs), bulletproof windows, sunglasses, greenhouse enclosures, outdoor fixtures, medical devices, computers and lab equipment are just a few examples. The cockpit canopy of the F-22 Raptor jet fighter, made from a sheet of high optical quality polycarbonate, is the largest piece of its type used in aviation. This canopy provides excellent visibility and performance at supersonic speeds and high g-force conditions, and can withstand the impact of a four-pound bird at 350 knots.
Today the polycarbonate industry is essentially controlled by eight companies around the world. Our customer in China, who has access to low cost bisphenol A, intends to become an independent producer of certain special polycarbonate formulations. In order to optimize key process parameters and generate test quantities of the product, the customer contracted Unitel to engineer and design a general purpose polycarbonate pilot plant with a nameplate capacity of 25 kg/hr.
The design created by Unitel included a polymerization section including an oligimerization reactor followed by tubular reactors. Bisphenol A, along with an alkali, is fed in the aqueous phase, and phosgene is introduced in an organic phase. The polymerization stage is followed by a wash section with a multiple centrifuge cascade. The washed product is devolatilized and pelletized. A special section enables solvent recovery and recycle.
Engagement: C, B, D. Status – completed.