Biodegradable multilayer material with adjustable gas transmission rate and preparation method and applications thereof

Abstract

The invention relates to a biodegradable multilayer material, which can be a thin film material or a sheet material. The biodegradable multilayer material at least comprises one of an adipic butanediol terephthalate copolymer (PBAT)/PBAT-chain extender-polypropylene carbonate (PBAT-Co-PPC)/PPC blend layer, a PBAT/PBAT-chain extender-polylactic acid (PBAT-Co-PLA)/PLA blend layer and a PBAT/PBAT-chain extender-polyhydroxyalkanoate (PBAT-Co-PHA)/PHA blend layer, and blend resins are respectively prepared through twin-screw reactive extrusion. The multilayer material is produced by using extrusion and coextrusion methods, has a function that the transmission rates of oxygen, carbon dioxide and water vapor can be adjusted, and can be applied to the packaging field and the agriculture field, and especially applied to food packaging, pharmaceutical packaging, and ground film mulching.

Description

technical field [0001] This technology relates to a biodegradable multi-layer film material or sheet material, which has the function of adjustable oxygen, carbon dioxide and water vapor transmission rate, and can be used in the field of packaging and agriculture, especially for food packaging and medical packaging , Ground covering film. Background technique [0002] After the use of traditional plastic packaging, because it is not recycled or discarded in the natural environment because it is not easy to recycle, it pollutes the environment. Therefore, biodegradable materials and their packaging products have gradually become the current research and development hotspots. my country's national standard GB / T20197 stipulates that if a single material is tested according to GB / T 19277.1, its biodegradation rate is 60% and it is a biodegradable material. So far, the types of biodegradable plastics that have been scaled or piloted include polylactic acid (PLA), polyhydroxyalka...

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Problems solved by technology

[0005] CN200380105492.0 has reported a kind of co-degradable multi-layer film, which is mainly obtained by multi-layer co-extrusion of a starch mixture layer containing 1-10% and a biodegradable polyester layer, although the patent application In the claim, it can block oxygen, nitrogen, carbon dioxide and water vapor, but it has some disadvantages: (1) The formula contains a starch mixture, which requires thermoplastic modification of the starch, and the addition of starch makes the overall material Decreased physical properties and poor long-term storage; (2) The biodegradable polyester layer is a mixture of various simple polymers, and the polymers are completely physically mixed with poor compatibility, so some compatibilizers and other additives should be added To make up for these defects; (3) Although the multilayer film can be composed of more than two layers, only three layers are preferred, because the compatibility between the layers needs to be achieved through starch mixture or softener, which increases the processing time. Difficulty, and these compatibilizers are easy to migrate or precipitate, which will affect the performance of the product; (4) The materials used in the multi-layer film have no biodegradable materials such as polypropylene carbonate with good oxygen barrier properties at that time, so In CN200380105492.0, materials such as polypropylene carbonate are not utilized; (5) the finished product of the multilayer film has less oxygen permeability due to the barrier aspect, and has a blocking effect on nitrogen, carbon dioxide and water vapor, but only plays a blocking role. and degradation permeation, but cannot adjust the size of gas permeation according to the needs of the packaged fresh food

Although the material barrier property of this technology product is improved after three-layer composite, it has the following disadvantages: (1) Since the middle layer only uses PPC layer, the inner and outer layers are respectively made of PBA-Co-PC and PLA-Co-PC as compatible materials. (2) Since the middle layer is only PPC, and the glass transition temperature of PPC is only 35°C, it is easy to deform at room temperature in summer, so multi-layer products are deformed due to the middle layer and become unstable in quality; (3) PBA-Co-PC and PLA-Co-PC copolymers are obtained by using isocyanate as a chain extender and polymerized by conventional techniques, so the process requires a polymer synthesis process, which is relatively complicated. And there are many by-products; (4) because the middle layer is fixed as the PPC layer, the composite film can only improve the barrier property, but it is difficult to realize the selective adjustability of gas permeability; (5) due to the use of isocyanate as the expansion Chain agent, so the composite film is limited when used in food packaging

[0007] In addition, there are also some reports of multi-layer co-extruded materials using traditional plastics such as polyethylene as the main raw material, which claim to be breathable, adjustable and degradable, but in fact they cannot be completely biodegraded and can only confuse right and wrong. Therefore, it is necessary to develop a gas-permeable Adjustable, stable physical properties and fully biodegradable multilayer materials are particularly important and necessary

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