Development and Application Prospect of Poly (lactic acid) Meltblown Nonwovens

Release time:

2021-11-15

PLA, also known as polylactide, is a completely biodegradable polyester polymer material. It is made by lactic acid polycondensation, at present, corn and other starch-containing biomass or straw cellulose as raw materials, fermentation production of lactic acid, lactic acid is prepared into a cyclic dimer lactide, and then lactide ring-opening polymerization to produce polylactic acid. It does not use petroleum as raw material, but only biomass renewable resources formed by photosynthesis of plants. In theory, the waste of polylactic acid products can be decomposed into carbon dioxide and water by microorganisms in nature. Carbon dioxide and water form biomass through plant photosynthesis and continue to become raw materials for polylactic acid fermentation. Therefore, polylactic acid is currently recognized as an environmentally friendly material in the world.

Raw Materials and Process Characteristics of PLA Meltblown Nonwovens

Process flow

PLA melt-blown nonwovens are made by melting PLA slices and blowing them with high-speed and high-temperature air flow to make the melt trickle extremely stretched to form ultra-fine short fibers, which are then gathered on rollers or mesh curtains to form fiber webs, and finally reinforced into cloth by self-bonding. The process flow is PLA slicing → drying → screw extruder melting → filter → metering pump → melt blowing die head → melt trickle stretching → fiber cooling → mesh laying receiving → adhesive synthetic cloth → winding.

Performance characteristics

PLA meltblown nonwovens have many characteristics, which can be summarized as follows:

(1) biodegradable, in line with the concept of sustainable development;

(2) It has good weather resistance and good strength at room temperature;

(3) due to the use of meltblown technology, its fiber is very fine, many pores and small size, in filtration, bacteria resistance, adsorption and other aspects have outstanding advantages.

PLA Raw Material and Its Meltblown Nonwovensdevelopment application

Development and Capacity of PLA Raw Materials

In 1954, DuPont (DuPont) Company of the United States began to prepare PLA by indirect method, I .e. lactide was prepared first, and then purified lactide was subjected to ring-opening polymerization to obtain PLA with high molecular weight. During this period, some foreign companies developed PLA for absorbable biomaterials, such as surgical sutures and carriers for drug release resistance systems. In 2001, Nature Works of the United States commercialized PLA products.

At present, the production of PLA in China is still in its infancy. Previously, there were technical barriers to the intermediate raw materials for PLA synthesis, and most of the PLA fiber-grade chips were imported. In recent years, some enterprises have broken through the technical bottleneck, and PLA fiber grade chips have a production capacity of tens of thousands of tons. According to data, PLA has been put into production, under construction and proposed nearly 20 enterprises at home and abroad, mainly concentrated in foreign countries, with the United States Nature Works as the largest, accounting for more than 30% of the world's production capacity.

Major global polylactic acid manufacturers

Source: China Spinning and Melting Nonwovens, No. 5, 2020.

Development Status of PLA Meltblown Nonwovens

Many years ago, there were colleges and enterprises in China to research and develop melt-blown nonwovens technology to process PLA, but there has been no mass production. The reason is that the cost of raw materials is high and the market acceptance is limited. In addition, the production process of PLA is not mature enough with traditional PP meltblown nonwovens equipment. In particular, PLA meltblown cloth, which is used as a high-end filter material, has a technical bottleneck in improving filtration efficiency. At present, some enterprises are exploring the effect of improving filtration efficiency and reducing filtration resistance by modifying PLA (maintaining biodegradability), adding resident masterbatch and treating PLA meltblown cloth with resident treatment.

With the expansion of domestic PLA raw material production scale, the improvement of process technology, the reduction of production costs, raw material prices will decline. Meltblown nonwovens production enterprises to further segment the market, can be aimed at some of the high-end consumers concerned about green health products, such as maternal and child products can be a step ahead; at the same time with policy guidance and support, the whole society to form a consensus, so that environmental protection is necessary.

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