Preparation method of heat-resistant polylactic acid biodegradable material

Abstract

The invention relates to a method for preparing a polylactic acid biodegradable material by chemical polymerization, which takes lactic acid as a raw material and comprises an esterification dehydration step and a polycondensation step. After the esterification dehydration step is finished and before the polycondensation step is finished, a catalyst, a nucleating agent and a chain extender are added into a reaction kettle, wherein the nucleating agent is a mixed emulsion formed by completely dissolving disodium salicylate solids in a resin emulsion, and the adding quantity of the nucleating agent is 5-25% of the total weight of the heat-resistant polylactic acid; the resin emulsion is an epoxy resin emulsion or a polyurethane resin emulsion or a combination of the epoxy resin emulsion and the polyurethane resin emulsion; and the chain extender is a styrene-acrylic acid copolymer of which the number-average molecular weight is 7500-15000 and the side chain contains 6-7 epoxy groups, and the adding quantity of the chain extender is 0.5-5% of the weight of the heat-resistant polylactic acid. In the method provided by the invention, talcum powder is not used, the production process can be controlled easily, and the prepared polylactic acid biodegradable material has excellent heat resistance and is suitable for industrialized production.

Description

technical field [0001] The invention relates to a preparation method of a heat-resistant polylactic acid biodegradable material. Background technique [0002] In recent years, with the improvement of environmental protection awareness, degradable biopolymer materials have received extensive attention, and the development and preparation of such materials are also current hot research topics. Among them, polylactic acid (also known as polylactide, polylactide, PLA, belonging to aliphatic polyester) is the most typical and widely used biodegradable plastic, which can be prepared by polymerization using lactic acid as the main raw material. And it can be regenerated (for example, using corn, cassava, etc. as raw materials). The production process of polylactic acid is non-polluting. Under certain conditions and time in the natural environment, it can be decomposed into carbon dioxide and water and returned to nature (rejoining the photosynthesis process of plants) Middle), to ...

AI Technical Summary

Problems solved by technology

In the related research on the preparation and modification of polylactic acid, it was proposed that CaCO 3 、TiO 2 and BaSO 4 Inorganic salt is added to polylactic acid as a nucleating agent, but it has not been able to achieve industrial production so far; some people use talcum powder as a nucleating agent, which is currently the only nucleating agent that can be applied to the industrial production of polylactic acid, but talc powder The particle size, content, shape regularity, etc. have a great influence on the crystallization nucleation effect of polylactic acid, which makes it difficult to control the industrial production of polylactic acid

For example, if the particle size of talc powder is too small, the dispersibility is not good, resulting in secondary agglomeration, the effect of crystallization nucleation cannot be fully exerted, and the problem of poor heat resistance cannot be fully solved; if the particle size is too large, the talc particles will become formed again. Defects in the product will have adverse effects on the physical properties or surface state of the polylactic acid material; when the content is too low, only a small amount of crystallization nuclei will be generated, resulting in insufficient heat resistance of the material, and if the content is too high, it will easily cause the polylactic acid material to become brittle , causing adverse effects on physical properties

In addition, in the process of industrial production and application, the dust of talcum powder will bring harm to the health of operators

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