Physical-aging-resistant biaxially-oriented polylactic acid membrane material, and preparation method and application thereof

Abstract

The invention discloses a physical-aging-resistant biaxially-oriented polylactic acid membrane material as well as a preparation method and application thereof. The polylactic acid membrane material comprises 35 wt%-85 wt% of a crystalline phase and 15 wt%-65 wt% of an amorphous phase, wherein the amorphous phase comprises 5 wt%-55 wt% of a metastable phase, and a characteristic peak of the metastable phase in an infrared spectrogram appears at 918 cm<-1>. The biaxially-oriented polylactic acid membrane material provided by the invention has the characteristic of physical aging resistance, andis relatively small in change rate of tensile strength, bending strength and elongation at break before and after storage, and relatively high in crystallinity and orientation degree. Products such as a polylactic acid packaging material prepared from the biaxially-oriented polylactic acid membrane material have the strength equivalent to or superior to the strength of an existing polylactic acidpackaging material, also have excellent physical aging resistance and can maintain stable in size and performance in a warehouse logistics stage. The preparation method is simple in process and beneficial to large-scale production, and has wide application prospects.

Description

technical field [0001] The invention relates to a polylactic acid material, in particular to a biaxially stretched polylactic acid film material resistant to physical aging, its preparation method and application (packaging materials, envelope windows, disposable cups, dinner plates, etc.), belonging to film material technology field. Background technique [0002] With the vigorous development of the petroleum industry and the needs of the production industry, a large number of petroleum-based polyesters, polyolefins, polystyrene and other resins are made into films every year for packaging and laminating materials. In addition, the market share of plastic packaging products is increasing year by year, especially composite plastic flexible packaging, which has been widely used in food, medicine, chemical and other fields. Among them, food packaging accounts for the largest proportion, such as beverage packaging, quick-frozen food packaging, retort food packaging, fast food ...

AI Technical Summary

Problems solved by technology

[0005] Although the above prior art can prepare polylactic acid film, there are the following limitations: (1) under the current technical conditions, the heat-set biaxially stretched polylactic acid film is easy to cause physical aging in the storage and logistics stage to cause rapid embrittlement; (2) heat-set biaxially stretched polylactic acid film, the preparation of food packaging materials requires high-temperature hot rolling, which further accelerates physical aging and causes brittleness; (3) biaxially stretched polylactic acid film without heat setting is subjected to high-temperature hot rolling (4) The biaxially oriented polylactic acid film and its packaging materials that have been heat-set or hot-rolled are also prone to physical aging during the use stage, resulting in rapid brittleness; Therefore, it is necessary to develop new polylactic acid membranes resistant to physical aging and their preparation methods to meet the higher requirements of various applications for their comprehensive performance.