BIDIRECTIONAL SHRINKABLE BIODEGRADABLE FILM AND PREPARATION METHOD THEREOF

摘要

PURPOSE: A bidirectionally shrinkable biodegradable film is provided to ensure excellent impact resistance, flexibility, and transparency, and to enable uniform contraction in a contraction tunnel due to low initial shrinkage speed. CONSTITUTION: A method for preparing a bidirectionally shrinkable biodegradable film comprises the steps of: (i) melting and extruding a polylactic acid resin containing 80 weight% or more of L-lactic acid as a main component; (ii) drawing the molten undrawn film in a longitudinal or traverse direction at a temperature higher than a glass transition temperature of a raw resin; (iii) thermally fixing the biaxially drawn film at a temperature lower than the raw resin; and (iv) cooling the film.