| 摘要 |
<p>PURPOSE:To obtain a large number of fine and uniform air bubbles by infiltrating an inert gas into a molten thermoplastic resin by an adaptor having the mixing part communicating with a first extruder and lowering the melting temp. while keeping a pressurized state by a second extruder and generating a large number of air bubble nuclei by the sudden lowering of pressure to control them. CONSTITUTION:An gas and a molten thermoplastic resin are kneaded in the barrel 10 of a first extruder 1 by a screw 11 and sent to an adaptor 2 having a mixing part controlled in pressure and temp. in order to enhance the solubility of the inert gas with respect to the thermoplastic resin to be further mixed. Next, the molten mixture is sent to a second extruder and the temp. thereof is lowered to temp. suitable for foaming, that is, the temp. of a nucleus forming device 4 being a foaming process while pressure is kept and subsequently lowered in its pressure suddenly in the nucleus forming device 4 to generate a large number of air bubbles. The foam is formed into a sheet by extrusion molding and cooled to control the growth of air bubbles to obtain a thermoplastic resin foam having a large number of fine and uniform air bubbles.</p> |
