Injection molding of polyarylene sulfide compositions

摘要

A method for injection molding a thermoplastic composition that contains a polyarylene sulfide and a boron-containing nucleating agent is provided. By selectively controlling certain aspects of the polyarylene sulfide and nucleating agent, as well as the particular manner in which they are combined, the crystallization properties of the resulting thermoplastic composition can be significantly improved. This allows the “cooling time” during a molding cycle to be substantially reduced while still achieving the same degree of crystallization. The cooling time can be represented by the “normalized cooling ratio”, which is determined by dividing the total cooling time by the average thickness of the molded part.

主权项

1. A method for injection molding a thermoplastic composition, the method comprising:
injecting a thermoplastic composition into a mold cavity, wherein the thermoplastic composition comprises a polyarylene sulfide, an organosilane coupling agent, and boron nitride, and wherein the composition has a crystallization potential of about 52% or more, as determined by differential scanning calorimetry; subjecting the thermoplastic composition to a cooling cycle to form a molded part having a certain average thickness, wherein the cooling cycle has a normalized cooling ratio of from about 0.2 to about 8 seconds per millimeter, as determined by dividing the total time of the cooling cycle by the thickness of the molded part; and ejecting the molded part from the mold cavity.