Full bio-based polylactic acid foaming material and preparation method thereof

Abstract

The invention discloses a full bio-based polylactic acid foaming material and a preparation method thereof. The method comprises the following steps: mixing dried L-polylactic acid and D-polylactic acid, and then adding a mixture to a twin-screw extruder and subjected to melt blending to obtain a polylactic acid containing a stereocomplex crystal; placing the material into an extrusion foaming machine to melt the material, then inputting a gas foaming agent into a screw through a gas injection port metering pump on the extrusion foaming machine, and uniformly mixing the material with a polylactic acid melt; reducing the temperature from a gas injection port to the screw at a head so that the temperature of the melt at the head is 110-140 DEG C and the pressure at the head is 6-8MPa, and finally performing extrusion foaming through a die, and performing cooling and fixing to obtain the polylactic acid foaming material. The method adopts L-polylactic acid and D-polylactic acid as raw materials, and forms the polylactic acid containing a stereocomplex crystal in the process of melt blending, which can significantly improve the melt strength and crystallization property of the polylactic acid. Therefore, the obtained polylactic acid foaming material has stable quality, uniform foam size, high foam density, and high foaming expansion ratio.

Description

technical field [0001] The invention belongs to the technical field of polymer material processing and microcellular foaming, and in particular relates to an all-bio-based polylactic acid foaming material and a preparation method thereof. Background technique [0002] Foamed plastic is a polymer-based microporous material containing a large amount of gas inside, which can be regarded as a special polymer / gas composite material. Due to the presence of the gas phase, foamed plastics combine the performance characteristics of both gas and polymer. Compared with unfoamed materials, foamed plastics have the characteristics of light weight, high specific strength, high impact strength, sound insulation, heat insulation and strong absorption capacity. They are used in packaging, automobiles, transportation, daily necessities, sports equipment and construction industries. have wide applications. However, the foaming materials widely used in industrial production are mainly soft an...

AI Technical Summary

Problems solved by technology

However, this technology uses chemical foaming agents for foaming, and at the same time adds additives such as chain extenders and plasticizers. The residue of small molecular substances will not only affect the mechanical properties of polylactic acid foaming materials, but also limit its application in food packaging.

CN201210032907 discloses a kind of polylactic acid degradable foaming and preparation method thereof, this technology adopts traditional chemical foaming agent, utilizes cross-linking agent to improve the melt strength of polylactic acid simultaneously, but after the chemical foaming agent decomposes, the inorganic substance Residues will affect the application range of polylactic acid foam materials, and the addition of cross-linking agents makes polylactic acid cross-linking difficult to recycle, which damages the original intention of using it as a biodegradable material

[0005] The second is to add another polymer to form a polymer blend, CN201210163071 and CN201010231424, etc. The addition of the second component will improve the foaming performance of polylactic acid to a certain extent, but due to the compatibility between different polymers Low, the performance uniformity and mechanical properties of the resulting blends are generally poor, and the addition of various compatibilizers will not only increase the complexity of the operation process and production costs, but also damage the biodegradability of polylactic acid , it is difficult to produce industrially

However, the introduction of nanoparticles also presents some challenges, such as difficulty in dispersing and increasing the price of the product

At the same time, in the process of production and use, the escape of nanoparticles will affect the health of production personnel

In addition, these fillers can also affect the biological characteristics of PLA materials

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