This invention relates generally to plastic molding, and more particularly to mold release agents, a method of extracting of such mold release agents from starting material, and a method of utilizing such release agents on molds for molding plastic parts.
In many molding operations wherein plastic parts are molded, it is necessary to utilize a mold release agent. Mold release agents are applied to the mold to prevent sticking of the plastic parts to the mold cavity walls. The release agents are applied periodically after a predetermined number of shots have been made.
In a typical transfer molding operation of novalac plastic parts, carnauba wax is used as the mold release agent. A block or stick of the carnauba wax is rubbed onto the heated (175.degree. C.) mold surfaces and then a brush is used to spread the carnauba wax over the surface of the mold. This process has several drawbacks.
First, it is necessary to run four or five shots of material after the application of the wax to make sure that there is no excess of wax present which can contribute to a poor surface quality and cause flakes of wax to become entrapped in the molded parts. These shots can be of novalac but more typically they are of a melamine material which acts as a good cleaning agent. In any event, these do not produce usable parts and the so molded parts must be scrapped.
After these cleaning shots, parts are molded. The duration of the mold release action is only about 10 to 20 shots, at which time the wax has to be re-applied and the whole cycle repeated. This is a costly and inefficient operation.