Process for forming blend of polyalkylene terephthalate and wholly aromatic polyester which exhibits an anisotropic melt phase

摘要

An improved process for producing a polymer blend which exhibits an anisotropic melt phase and is capable of forming shaped articles having satisfactory mechanical properties (e.g. tensile strength, flexural strength, and Izod impact strength) is provided. The process comprises the steps of (a) post-polymerizing a melt processable wholly aromatic polyester which is capable of forming an anisotropic melt phase apart from the blend and (b) subsequently intimately mixing together approximately 85 to 95 percent by weight of the wholly aromatic polyester and approximately 5 to 15 percent by weight of a polyalkylene terephthalate. Accordingly, the wholly aromatic polyester which is capable of forming an anisotropic melt phase serves as the continuous phase in the resulting blend. The post-polymerization step is conducted at a temperature and for a period of time sufficient to increase the inherent viscosity of the wholly aromatic polyester by at least approximately 50 percent, preferably by at least approximately 100 percent. Each of the shaped article mechanical properties identified above is improved over that of the composition in the absence of the polyalkylene terephthalate. The polyalkylene terephthalate is preferably polyethylene terephthalate.