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Biaxially stretched polylactic acid film material resistant to physical aging, its preparation method and application

A biaxial stretching and physical aging technology, used in applications, other household appliances, flat products, etc., can solve the problems of accelerated physical aging, brittleness, etc., to maintain stability, simple preparation process, and excellent resistance to physical aging. Effect

Active Publication Date: 2022-03-15
NINGBO INST OF MATERIALS TECH & ENG CHINESE ACADEMY OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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.

Method used

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preparation example Construction

[0027] In some embodiments, the preparation method specifically includes:

[0028] (1) Provide dry polylactic acid or polylactic acid dry mixture;

[0029] (2) extruding the dry polylactic acid or polylactic acid dry mixture through casting equipment to form a casting sheet, wherein the extrusion temperature used is 160-220°C, and the temperature of the casting roll is 20-50°C;

[0030](3) Biaxially stretch the cast sheet after fully preheating, first carry out longitudinal stretching (MD) of the film, the stretching temperature is 85-140°C, and the stretching ratio is 2-5 times, and then carry out Transverse stretching (TD) of the film, the stretching temperature is 90-145°C, the stretching ratio is 2-5 times, and then rapidly quenched to room temperature at a quenching rate of 2.5-140°C / s, and the quenching time is 1-5 times In 59 seconds, a biaxially oriented polylactic acid film was prepared.

[0031] In some embodiments, step (1) includes: hot-air drying the polylactic ...

Embodiment 1

[0072] Take polylactic acid with a weight average molecular weight of 150,000 and a molar content of L optical isomer of 95% for hot air drying at a drying temperature of 95±2°C, a drying time of 8 hours, and a water content of 50ppm; The material is extruded through the casting extrusion equipment to form a casting sheet, the extrusion temperature is 190 °C, and the temperature of the casting roll is 35 °C; the casting sheet is fully preheated and biaxially stretched. ) stretching, the stretching temperature is 90°C, and the stretching ratio is 5 times; followed by film transverse (TD) stretching, the stretching temperature is 100°C, and the stretching ratio is 3 times; immediately enter the rapid cooling device to obtain two-way stretching Stretch the polylactic acid film, the quenching rate is 30° C. / sec, and the quenching time is 3 seconds; the thickness of the above-mentioned biaxially stretched polylactic acid film is 30 microns; then the polylactic acid film is put into ...

Embodiment 2

[0074] Take polylactic acid with a weight average molecular weight of 80,000 and a molar content of L optical isomer of 99% for hot air drying at a drying temperature of 95±2°C, a drying time of 8 hours, and a water content of 40ppm; The material is extruded through the casting extrusion equipment to form a cast sheet, the extrusion temperature is 180 °C, and the temperature of the casting roll is 40 °C; ) stretching, the stretching temperature is 85°C, and the stretching ratio is 3 times; followed by film transverse (TD) stretching, the stretching temperature is 90°C, and the stretching ratio is 3 times; immediately enter the rapid cooling device to obtain two-way stretching Stretch the polylactic acid film, the quenching rate is 70° C. / sec, and the quenching time is 1 second; the thickness of the above-mentioned biaxially stretched polylactic acid film is 20 microns; then the polylactic acid film is put into the warehouse for standby. When in use, the biaxially oriented poly...

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Abstract

The invention discloses a biaxially stretched polylactic acid film material resistant to physical aging, a preparation method and application thereof. The polylactic acid film material comprises 35wt%-85wt% crystalline phase and 15wt%-65wt% amorphous phase; the amorphous phase comprises 5wt%-55wt% metastable phase, and the metastable phase is shown in the infrared spectrogram The characteristic peak appears at 918cm ‑1 place. The biaxially stretched polylactic acid film material provided by the present invention has the characteristics of resistance to physical aging, the rate of change of tensile strength and bending strength before and after storage is small, the change of elongation at break is also small, and the degree of crystallinity and orientation are relatively high. , the polylactic acid packaging materials and other products made of it not only have the strength equivalent to or better than the existing polylactic acid packaging materials, but also have excellent physical aging resistance, which can maintain the stability of size and performance in the storage and logistics stage and its preparation process is simple, which is beneficial to large-scale production and has broad 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 ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C08L67/04C08J5/18B29C69/02
CPCC08J5/18B29C69/02B29L2007/00B29K2067/046C08J2367/04
Inventor 陈鹏黄威
Owner NINGBO INST OF MATERIALS TECH & ENG CHINESE ACADEMY OF SCI
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