Polycarbonate resin (PC resin) is a type of thermoplastic component used in the manufacturing of certain plastics. While the specific attributes of each resin differs according to its exact composition and extraction method, each is synthesized via catalyst from monomers called hydrocarbons, in a process known as condensation polymerization. The monomers used to produce polycarbonate resin differ from other types in that they contain amino, alcohol, or carboxylic acid functional groups. The chain reaction results in a covalent bond of one carbon atom bonded to three oxygen atoms, with small water molecules being displaced to yield a final polymer of high density and impact strength. These properties make polycarbonate resin suitable for manufacturing a wide variety of products that require exceptional stress and heat resistance, such as compact discs, hockey masks, eyeglasses, automobile parts, bulletproof glass, medical and aerospace equipment, and even shuttle parts for the U.S. National Aeronautics and Space Administration (NASA) space program.
Many products like those mentioned above are made by subjecting a polycarbonate resin to an injection molding process in which the polymerized material hardens inside a mold or die and permanently takes on its parent shape. In some cases, the end product may require treatment with a coating to provide additional insurance against damage from chronic exposure to ultraviolet radiation or certain chemicals. For instance, PC plastics cannot withstand contact with solvents such as benzene, acetone, or sodium hypochlorite, otherwise known as household bleach. Protective coatings also increase the surface resistance of products made from polycarbonate resin since they tend to be easily scratched.
The most common type of PC plastic is made by inducing resin polymerization through a chemical reaction between phosgene isocyanates and bisphenol A (BPA) monomers. In fact, numerous common household products are made from BPA-based plastic ranging from electronic and computer components to baby bottles and food storage containers. Since BPA is now known to be an endocrine disruptor associated with infertility, birth defects, neurological disorders, and hormone-dependent cancers, its impact on human health for more than half a century is of great concern, as well as its continued use. Yet, in spite of numerous international studies and reports on the subject, very few countries have considered banning or modifying the use of BPA in the plastics industry. However, Denmark moved to ban the use of BPA in baby bottles in 2009, and several U.S. states have independently banned its inclusion in all reusable food and beverage containers, as well as those that store infant formula and food.
