Kettle-type synthesis method of polylactic acid with high melt index and modified polylactic acid prepared thereby

Abstract

The invention discloses a kettle-type synthesis method of polylactic acid with a high melt index, relates to the field of polymer composite materials, and aims at solving the problems of high equipment cost, high energy consumption and low melt index of the existing polylactic acid preparation. The preparation method comprises the following steps: (1) adding polylactic acid particles, a degradation agent and a dispersing solvent into a high-temperature reaction kettle according to a mass ratio of 100:3:50-100:5:50; (2) heating the reaction kettle to 70-100DEG C, continuously performing stirring for 0.5-8.0h, and then performing cooling; and (3) filtering the mixture in the reaction kettle, and drying the solid substance to obtain the modified polylactic acid. The invention also discloses the modified polylactic acid prepared by the preparation method. Compared with a screw extruder, the kettle type production equipment is small in occupied area and low in energy consumption; the melt index of the modified polylactic acid is controlled by adjusting the reaction temperature, the reaction time and the addition amount of the degradation agent, the melt index is very stable and is 1500-2900g / 10min, and the standard of the melt index of a common melt-blown high-molecular polymer is met.

Description

technical field [0001] The invention relates to the technical field of catalysts, in particular to a still-type synthesis method of polylactic acid with a high melt index and the prepared modified polylactic acid. Background technique [0002] With the outbreak of the new crown pneumonia epidemic in early 2020, the demand for masks and the core raw material of masks-melt blown cloth continues to increase. The main raw material of melt-blown cloth for masks is melt-blown polypropylene. However, traditional polymer plastics such as polyethylene, polypropylene, and polyvinyl chloride not only need to consume fossil resources in the production process, but also are very difficult to degrade. It may take hundreds of years for an discarded mask to degrade in the natural environment. With the new version of the country's "Plastic Restriction Order", the "Notice on Solidly Promoting Plastic Pollution Control Work" stipulates that by the end of 2020, it will take the lead in banning...

AI Technical Summary

Problems solved by technology

In Chinese patent CN105368017A, polylactic acid with a melt index of 5-50g / 10min is dry-blended with initiator and auxiliary additives in a high-speed mixer, and then sent to a twin-screw extruder for melt extrusion and granulation to obtain melted High melt index polylactic acid products with an index of 2000-5000g / 10min, but due to the limited screw length and high modification temperature in the screw extrusion method, the molecular weight distribution of polylactic acid products is wide and the melt index is unstable; and the modified After polylactic acid is extruded and pelletized, it is more difficult to chemically modify it again

In the Chinese patent CN107304287A, flow modifiers, lubricants, antioxidants, inorganic fillers and other auxiliary materials are added to the polylactic acid raw materials, but the melting index of the polylactic acid resin composition obtained by this technology is only 85g / 10min, low melt index

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