| 摘要 |
<p>A mixture of crumb rubber, binder, such as polyethylene, and slip contact agent, such as talc, and lubricant, such as a metal stearate, is formed in a blender (10), is shaped into pellets (32) by extruding a strand of the mixture (26) into water (28) and breaking the strand into pellets. The pellets (32) are adjusted to a preselected water content in drier (46) before storage in closed bags (50), stored and reinforced in a container (54). The controlled water content pellets (32) are formed into porous pipe (88) by extrusion in pipe extruder (62) having the feeding, transition and metering zones separately heated to temperatures from 320 DEG F. to 400 DEG F. (T1, T2, T3). The die has a separate jacket (90) receiving heat exchange fluid for heating the die (68) to a temperature from 290 DEG F. to 380 DEG F. to form a porous pipe (88) having more uniform porosity. Porosity is controlled by selecting water content of the pellets and controlling die temperature.</p> |
