US 5,158,725 A · Continuous mixing of elastomeric compounds

Abstract

An elastomer masterbatch or a compounded productive elastomer stock is made using a twin screw extruder to mix elastomer components in multiple mixing zones at controlled temperatures. Elastomer and other ingredients are fed into the twin screw extruder continuously through precise loss-in-weight or volumetric feeders. The degradation temperature and/or cross linking temperature of the elastomer determines the rate at which the elastomer can be processed, since friction created during mixing heats the elastomer. Accordingly, the maximum rate of compounding is a function of the torque limit, cooling efficiency, and conveying capacity of the extruder. The conveying capacity and torque limit are also a function of the size of the extruder. The viscosity of the elastomer compound in the extruder, as measured by a Mooney viscosimeter (ASTM D1646), is typically in the range of about 20 to 250 units (ML(1+4)100C).

Claims12

Dependent claims

A method for the continuous mixing of elastomer compounds comprising the steps of:

a) providing a twin screw extruder comprising a housing containing feed openings and a discharge opening,
b) feeding an elastomer continuously in a controlled manner into the extruder through a feed opening,
c) feeding at least one filler, additive oil, and/or another elastomer in a controlled manner into said extruder through a feed opening or openings,
d) mixing the ingredients of step (c) using said screws with said elastomer as they are added to the housing to provide a mixture,
e) maintaining said mixture at a Mooney viscosity ASTM-D 1646 (ML(1+4) 100C) between 20 to 250 units during mixing, and
f) discharging the mixture from the discharge opening of the extruder.

3 more elements

Dependencies are inferred from the claim text.

Continuous mixing of elastomeric compounds

Life of this patent

Continuous mixing of elastomeric compounds

Life of this patent

Abstract

Claims12