MANUFACTURE OF BIAXIALLY STRETCHED TRANSPARENT POLYSTYRENE RESIN SHEET

摘要

PURPOSE:To obtain the titled sheet having improved physical properties and large in strength by mixing styrene butadiene block copolymer (SB) containing a large quantity of styrene (St) component and polyisoprene or SB containing a small quantity of St component. CONSTITUTION:When SB containing St component of 60-90wt% (A) and SB containing polyisoprene or St component of 50% or less (B) are mixed, resin composition wherein the weight ratio of component A to component B ranges from 1-10 and the content of the component B to the whole components of the sheet ranges 1-5% is extruded from an extruder and stretched biaxially by the inflation process, th tenter process, etc. up to the stretching magnification 1.8 times or more to obtain the desired sheet. When the longitudinal and lateral elongation percentage are represented respectively by alpha and beta the stretching magnification may be shown by the geometrical average value (alphaXbeta)<1/2>.