Development of Conjugated In-mold Reaction Molding of Thermoset and Themoplastic Resins

Abstract

Both thermosetting resins and thermoplastic resins have special desireable properties that are possessed by one, but not the other. This investigation involved a study of the development of conjugated molded parts that possess both sets of desireable characteristics as well as a study of the molds necessary for making these parts. A new molding technique has been developed in which rapid heating and coolling is performed by means of high-frequency induction heating. In this study, we report on studies using a modified technique in which the mold is heated and coolled at arbitrary times during the molding process in an ordinary injection machine combined with a high frequency generator. A high-frequency heating inductor is embedded in the mold. The molding process that was developed is as follows: (1) An uncured solution of Diallylphthalate (DAP) is sprayed onto the mold cavity surface. (2) After closing the sprayed mold, a thermoplastic is injected at ordinary resin injection temperatures (to investigate their conjugation with DAP). (3) The mold is heated by high-frequency induction heating, which cures the DAP. (4) The mold is cooled and the molded part released from the mold.The results that were obtauned are as follows: (1) The conditions for hardening the DAP were: mold temperature 140-150°C for 1-5mins. (2) The curing of the DAP: cured by heating after the conjugation. (3) Thermoplastics capable of conjugation with DAP: SAN and ABS resins.This method has led to the successful development of a new conjugated molding process, in which a thermoplastic resin (such as DAP) reacts and cures in the mold, while being conjugated with an injected thermoplastic resin (such as SAN or ABS).