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United States Patent 5204039
Douris , ê et al. April 20, 1993

Extrusion method and extruder used for obtaining phenolic resin pipe

Miyasaka , Ê et al. April 20, 1993

Abstract

An extrusion method for obtaining a long phenolic resin pipe having excellent heat resistance by using an extruder having a screw, a cylinder, a die and a mandrel, the mandrel being inserted into a through-hole formed in the screw along the screw axis and protruding into the die along the screw axis, the die satisfying the following formulas R.sub.1 /R.sub.2 =0.25.about.1.0 S.sub.1 /S.sub.2 =0.1.about.2.5 where R.sub.1 is an outside diameter of the die flow path at the die outlet, S.sub.1 is a cross-sectional area of the die flow path at the die outlet, R.sub.2 is an outside diameter of the die flow path at the die inlet, and S.sub.2 is a cross-sectional area of the die flow path at the die inlet, and the inclination of the outer periphery of the die flow path portion from the die inlet to a starting point of the uniform flow path portion having the same cross section as the die outlet is not larger than 35.degree. to the axis of the screw, and by shaping and extruding a phenolic resin material in a state that the material after extrusion is cured so as to be able to retain its own shape, by controlling the temperature of the heating zone of the cylinder communicating with the die inlet at 120.degree.-145.degree. C. and the temperature of the die at 150.degree.-200.degree. C.; an extruder for carrying out the method; and an extruded article obtained by the method and the extruder.