Opt. crosslinked polyethylene foam sheet - produced by extrusion of specified compsn. into sheet, wound and unwound in oven having temp. gradient

摘要

2-step prodn. of opt. crosslinked polyethylene foam from a PE compsn. contg. heat sensitive additives comprises: (1) Introduc-ing LDPE of density below 0.910 and M.1. below 3 g/10min into an extruder simultaneously with 1.5-25 pts. blowing agent and 0-2pts. crosslinking agent (per 100 pts. PE) to form a mixt. heated at a temp. sufficient to soften the polymer without exceeding 135 deg.C extruding a sheet of homogenesus compsn. and winding the obtd. sheet, and (2) unwinding the sheet, passing it in an oven in which a temp. gradient of 140-260 deg.C is maintained to expand and crosslink the sheet and recover-ing the foamed sheet at the outlet of the oven, the sheet contg. pores of average size below 0.4 mm.