Non-symmetry structure for seven-layer laminated coiling-resistant composite film

Abstract

The seven-layer coextruded antiswarp composite film with nonsymmetric crystalline characteristics possesses the following structure expression formula: A / B / C / A / B / C, where A is crystalline resin layer, B is adhesive resin layer and C is amorphous resin layer. According to the principle of mechanical equilibrium said invention utilizes the identical charateristics of same kind or same type of materials of design the above-mentioned second layer, third layer and fourth layer into balance bridge structure, and uses said balance bridge structure to counteract the stress imbalance resulted from different crystalline temp. between other layers so as to effectively overcome warp.

Description

technical field [0001] The invention relates to a multi-layer co-extruded blown composite film, in particular to an anti-curl asymmetric structure of a seven-layer co-extruded blown composite film with a crystalline resin layer, an amorphous resin layer and an adhesive resin layer as unit layers . This seven-layer co-extrusion blown composite film with an asymmetric structure has good barrier and heat sealing properties, and is especially suitable as a flexible packaging material with barrier function requirements. Background technique [0002] In the past ten years, the plastic packaging film market has undergone great changes, the most prominent of which is the growth of multi-layer co-extruded composite films, which not only shocked the packaging industry, but also quietly carried out a revolution in packaging films. [0003] The asymmetrical seven-layer co-extruded blown composite film is a seven-layer composite structure with asymmetric crysta...

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Problems solved by technology

[0004] Compared with the symmetrical structure, the asymmetric structure of the seven-layer co-extruded blown composite film has the advantage of taking into account the subsequent processing characteristics, but because of this, the most prominent problem is that it is extremely easy to produce a film during the co-extruded blow molding process. The mechanism of curling is: when the asymmetric structure formed by crystalline resin and non-crystalline resin is co-extruded and blow-molded under the same temperature and pressure conditions, the stress imbalance will inevitably occur due to the different crystallization temperature and rate of the material. thus directly causing the film to curl

However, this technology is still very unstable, and the main disadvantages are: 1. It is necessary to add more expensive auxiliary tank equipment; 2. Due to the difference in the thickness of various nylon structures, the influence of air temperature and humidity in the environment, and the residence time in the tank The effect of length makes the anti-frizz effect difficult to grasp

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