| 摘要 |
Hollow microporous profiles are made by extrusion of thermoplastic materials contg. relatively high amts. of blowing agents, specifically 1-5% wt. and at relatively high temps, specifically 5-30 degrees C above the extrusion temps normally used for obtaining a smooth finish. The material is extruded via a die having sharp corners at the die lips. Used for mfr. of aeration of irrigation conduits for distributing liquids or gases, or for drainage. Also for stock profiles for making porous articles such as flower pots, shoe soles, perfume or disinfectant dispersers, filters etc. The porosity is distributed more uniformly over the profile surface, the extrusion equipment is much simpler and throughputs much higher than for systems producing pipe with individual perforations at regular intervals. The surface has a rough, 'natural' texture. |
