Shrink film and preparation method thereof

Abstract

The invention provides a shrink film and a preparation method thereof. The shrink film comprises an outermost layer, a secondary outer layer, a middle layer, a secondary inner layer and an innermost layer which are arranged in sequence, wherein the outermost layer and the innermost layer as well as the secondary outer layer and the secondary inner layer are symmetrically distributed by taking the middle layer as an axis, the thickness ratio of the outermost layer to the secondary outer layer to the middle layer to the secondary inner layer to the innermost layer is (1.5-2.5): (0.3-0.7): (3-6): (0.3-0.7): (1.5-2.5); in percentage by weight, the outermost layer and the innermost layer are composed of 10-30% of LDPE or LLDPE and 70-90% of mLLDPE; the middle layer is composed of 45-70% of HDPE, 20-40% of LDPE and 10-15% of MDPE; and the secondary outer layer and the secondary inner layer are composed of 67-80% of ethylene-vinyl alcohol copolymer, 17-30% of ethylene-vinyl acetate or ethylene-propylene copolymer and 0.5-3% of tackifying additive. On the basis of EVOH, and by combining flexible resin EVA or EPM, the secondary inner layer and the secondary outer layer are clamped between the outermost layer / the innermost layer and the middle layer to serve as a thin buffer layer; and the interlayer cohesiveness is improved through a tackifying additive, so that the influence of external force on the high-toughness outermost layer and the high-toughness outer inner layer can be effectively relieved, and the high toughness of the shrink film can be effectively maintained.

Description

technical field [0001] The invention relates to the technical field of multilayer structures, in particular to a film, and more particularly to a shrink film and a preparation method thereof. Background technique [0002] As an industrial film product, shrink film has high tensile strength, high elongation, good self-adhesiveness, and high transparency. centralized packaging. It is particularly important that the stretch film packaging makes the packaged items evenly stressed and avoids damage to the items caused by uneven force, which cannot be achieved by traditional packaging methods (bundling, packaging, tape, etc.). At the same time, the product is wrapped and packaged with the help of the retracting force of the stretched film to form a compact unit that does not take up space, so that the pallets of the product are tightly wrapped together, which can effectively prevent the mutual dislocation of the product during transportation. And moving, at the same time, the ad...

AI Technical Summary

Problems solved by technology

[0003] However, in some special fields, such as beverages or other rolling objects for packaging, the toughness requirements for the shrink film are relatively high. At present, the common shrink film cannot meet the toughness requirements. The movement of the object causes the shrink film to be pulled and deformed or even torn, making it unusable

At the same time, the shrink film is usually a multi-layer structure, which is usually a three-layer body or a five-layer body. It is formed by co-extrusion blow molding, and its flexibility is not strong. Stratification appears due to the impact, thus affecting its use

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