초록 ▼

There is provided a process for producing a multi-layer molded product having a plurality of thermoplastic resin layers. This process provides for (i) a step of supplying first and second molten thermoplastic resins each through first and second resin supplying gates which are temperature-controllab

There is provided a process for producing a multi-layer molded product having a plurality of thermoplastic resin layers. This process provides for (i) a step of supplying first and second molten thermoplastic resins each through first and second resin supplying gates which are temperature-controllable independently of each other, to between female and male molds kept in an open state with a time difference being provided between supply starts of the first and second resins, and (ii) a step of closing the female and male molds after completion of supply of the first and second resins. The process enables production of high-quality multi-layer molded products having a plurality of resin layers with good repeatability under relatively low resin supply pressure and by single mold closing. Further, high-quality multi-layer molded products can readily be produced without restrictions on materials used.

대표청구항 ▼

[ What is claimed is:] [1.]1. A process for producing a multilayer molded product, comprising the steps of:providing female and male molds such that a mold cavity is defined therebetween, independent first and second resin-supplying gates, and independent first and second heaters to control respecti

[ What is claimed is:] [1.]1. A process for producing a multilayer molded product, comprising the steps of:providing female and male molds such that a mold cavity is defined therebetween, independent first and second resin-supplying gates, and independent first and second heaters to control respective temperatures of said first and second resin-supplying gates, wherein the first and second resin supplying gates are situated with respect to first and second heaters to control respective temperatures of said first and second resin-supplying gates, wherein the first and second resin-supplying gates are situated with respect to the molds such that(a) the gates separately extend from distinct points external to the molds to independent points between the molds in opposing fashion,(b) the gates are situated inside in either the female or the male mold, forming independent concentric rings, or(c) the gates are adjacent to each other within either the female or the male mold; thensupplying the first molten thermoplastic resin through the first resin-supplying gate to the mold cavity between the female and male molds kept in a open state, while the first heater controls the temperature of the first thermoplastic resin at a predetermined temperature higher than a melting point of the first resin and lower than a decomposition temperature thereof;permitting the first molten resin to form a surface layer;supplying the second thermoplastic resin in a molten state through the second resin-supplying gate to the mold cavity between the female and male molds kept in an open state, while the second heater controls the temperature of the second thermoplastic resin at a predetermined temperature higher than a melting point of the second resin and lower than a decomposition temperature thereof separately and independently of the supply temperature of said first resin, after a lapse of a predetermined period of time from supply start of the first thermoplastic resin, thereby forming a second layer;moving said female and male molds from the open state to a closed state whereby the cavity clearance is substantially coincident with the thickness of the desired multi-layer molded product;cooling and solidifying said first and second resins in the mold cavity in the closed state; andopening said female and male molds to take out the multi-layer molded product; wherein in the steps of supplying the first and second resins, the total volume of resin supplied is nearly equal to the final volume of the desired molded product, and whereby a cavity clearance greater than the thickness of the desired multi-layer molded product is achieved.