Co-extruded and bidirectional-stretched composite film and preparation method thereof

Abstract

The invention discloses a co-extruded and bidirectional-stretched composite film, which has a three-layered structure, namely a homopolymer or copolymer polypropylene resin assistant barrier layer, a homopolymer polypropylene resin assistant barrier layer containing adhesive resin and an ethylene-vinyl alcohol copolymer resin main barrier layer in turn, or a homopolymer polypropylene resin assistant barrier layer, an ethylene-vinyl alcohol copolymer resin main barrier layer and a homopolymer or copolymer polypropylene resin assistant barrier layer containing adhesive resin in turn, wherein the composite film is formed by co-extruding the three-layered structure and then stretching bi-directionally. The composite film provided by the invention has the combined advantages of high stretching intensity and good optical performance of the polypropylene resin layer and the advantage of high barrier property of the ethylene-vinyl alcohol copolymer resin layer, so that a film material with extremely high permeability resistance to oxygen, carbon oxygen, fragrance, smells, aqueous vapor and the like, high toughness and high antistatic property is obtained; the film is thin; the manufacturing cost is low and the yield is high.

Description

technical field [0001] The invention relates to an environment-friendly film, in particular to a co-extruded biaxially stretched composite film with high strength and high barrier performance, and also relates to a preparation method of the composite film. Background technique [0002] Multilayer co-extruded stretched film technology has been widely used. Some multi-layer composite films have appeared in the prior art, with ethylene-vinyl alcohol copolymer resin (EVOH) as the main barrier layer. Since EVOH is a crystalline polymer, its melting point is around 180°C, and its melting range is narrow. If the crystallinity is too high after longitudinal stretching, it will be difficult to stretch laterally again, and the film with too high crystallinity will break down. white phenomenon. Therefore, the biaxial stretching process of EVOH film has always been the bottleneck in production. [0003] Invention patent ZL99809184.7 "Method for Producing EVOH / Polyester Biaxially Stre...

AI Technical Summary

Problems solved by technology

PET is a kind of polyester, which has the advantages of high mechanical properties, but also has defects such as general tensile strength and poor optical properties.

And in order to realize the production of this multilayer film, need to redesign corresponding equipment, the production cost is high

[0004] Invention patent ZL02105126.7 "Manufacturing Method of Ethylene-Vinyl Alcohol Copolymer Biaxially Stretched Film" discloses the method of manufacturing ethylene-vinyl alcohol copolymer film by biaxial stretching, which also discloses that EVOH biaxially stretched film and other thermoplastic Layers made of resins together form a laminated product, but this laminated product is formed by laminating other thermoplastic resins with biaxially stretched EVOH film, and the degree of bonding between the layers is limited, which affects the quality of the laminated product. Gas barrier properties, form stability and transparency

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