PURPOSE: To improve crystal orientation and environmental stress cracking resistance of sealed parts of a low-density polyethylene film, by heat-treating the film obtained according to water cooling inflation under specific conditions.
CONSTITUTION: A low-density polyethylene resin is molded into a film by water cooling inflation. The film is heat-treated in a temperature range from 70°C to a melting point of the resin, preferably 80W105°C, for not less than 5 seconds and within a range shown by the formula [T is heat-treating temperature (°C); S is a heat-treating time (second)]
EFFECT: Improved impact strength of sealed parts.
USE: Bags of heavy packages for industrial products e.g., ammonium sulfate, urea, caprolactam, surfactant, etc., deteriorating polyolefin.
MATSUMOTO YOSHIO
IKETANI NOBUSHIGE
