Biodegradable multilayer composite barrier film and preparation method thereof

Abstract

The invention provides a biodegradable multilayer composite barrier film and a preparation method thereof. The biodegradable multilayer composite barrier film comprises a matrix layer, bonding layers located on the two sides of the matrix layer and barrier layers located on the sides, away from the matrix layer, of the bonding layers, the matrix layer is made of biodegradable resin, the bonding layers are made of polylactic acid modified by active groups, and the barrier layers are formed by drying a polyvinyl alcohol solution on the bonding layers. The barrier layers are formed by drying a polyvinyl alcohol solution, and a continuous and compact PVA layer can be formed, so that the gas barrier property is better. Active groups in the modified polylactic acid can chemically react with hydroxyl groups on a PVA molecular chain, so that the adhesive force of the barrier layers on the matrix layer is improved, the interlayer binding force reaches an inseparable degree, and the barrier property is further improved. The number of hydroxyl groups on a PVA molecular chain is reduced due to chemical reaction, so that the original water intolerance of PVA is improved, and the corresponding water vapor barrier property is also improved.

Description

technical field [0001] The invention relates to the technical field of plastics, in particular to a multilayer composite film, and more particularly to a biodegradable multilayer composite barrier film and a preparation method thereof. Background technique [0002] Since its inception, plastics have been widely used in various fields of the national economy, bringing great convenience to human production and life. However, its huge amount of use and waste has led to increasingly serious environmental pollution, that is, white pollution, including river pollution, farmland mulch pollution, and ocean plastic pollution. Therefore, in recent years, people have been looking for products that can replace traditional plastics. [0003] The emergence of biodegradable plastics has solved this problem well. Biodegradable plastics, also known as biodegradable plastics, refer to the action of microorganisms existing in nature under natural conditions such as soil and / or sandy soil, an...

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Problems solved by technology

[0006] However, the melting temperature of PVA is close to the decomposition temperature. When melting, PVA will be decomposed and carbonized in large quantities, so it is impossible to directly melt and extrude the pure PVA material to form a film. To realize the melt extrusion of PVA, a large amount of plasticizer must be added to reduce the Its melting temperature, and a large amount of plasticizers will reduce the crystallinity of PVA, making its molecular aggregation structure less compact, so its barrier properties will be greatly affected

In recent years, there have been reports of using PVA and other degradable plastics to prepare blended alloys, such as PLA / PVA alloys, PBAT / PVA alloys, and then using alloys to make films. However, due to the large amount of low-barrier plastics mixed into PVA, the PVA has excellent barrier properties. At the same time, the film is made of blend material. In the obtained film, PVA will be distributed in the film in the form of particles, and no dense PVA layer is formed, so the barrier property of the film is very general.

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