Method of making multilayer container

摘要

This invention relates to a method of making a multilayer container which comprises:
a primary stretching and heat-setting process wherein a multilayer sheet comprising a A-PET layer, a functional resin layer and a sealant layer, is heated, primarily stretched and then primarily heat-set, anda secondary stretching and heat-setting process wherein the multilayer sheet treated in the primary stretching and heat-setting process is molded with heating by a mold of a thermoforming machine while secondary stretching is performed, followed by secondary heat-setting in the same mold.

主权项

1. A method of making a multilayer container which comprises:
a primary stretching and heat-setting process wherein a multilayer sheet having a total thickness of 150 to 1000 μm and consisting essentially of an A-PET layer having a thickness of 100 to 600 μm, a functional resin layer and a sealant layer, is heated, primarily stretched and then primarily heat-set, and a secondary stretching and heat-setting process wherein the multilayer sheet treated in the primary stretching and heat-setting process is molded with heating by a mold of a thermoforming machine while secondary stretching is performed, followed by secondary heat-setting in the same mold, wherein the functional resin layer is composed of one or more layers which are an oxygen barrier layer selected from the group consisting of EVOH resin layer, PVDC resin layer, PAN resin layer and MXD6-NY resin layer, and/or resistance to dropping resin layer being NY resin layer, wherein the multilayer sheet is, in the primary stretching and heat-setting process, uniaxially stretched using rolls as the stretching apparatus at a stretching temperature of 90 to 120° C. at a draw ratio of 2 to 4 times in the MD (longitudinal) direction, and then primarily heat-set at a temperature higher than the stretching temperature by 5 to 20° C., wherein, in the secondary stretching and heat-setting process, the multilayer sheet is molded with heating at a temperature of 80 to 130° C., and the secondary heat-setting in the same mold consists of the step of heat-setting at a temperature of 20 to 70° C., and wherein the sealant layer is selected from the group consisting of polypropylene, polyethylene and LLDPE.