Master mixt. for adding to fresh PVC - by two stage mixing of minor proportion of PVC, and major proportion of another resin

摘要

Master mixt. for adding to fresh PVC is prepd. by (a) forming, in a rapidly operating, heated mixer, a first component formed by a mixt. of PVC and =1 additional resin, such as barrier resin, or a processing-aid resin for facilitating the mixing of the PVC with the other resin, and usual additives the amt. of PVC being that of the additional resins, (b) adding this first component to a second cold mixer, together with a second component consisting of additional resins and/or additives in a dry cold state, so that rapid dissipation of heat occurs, and (c) effecting good mixing of the components. Process gives a dry powdered master mixt. without degradation of the resins.