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What is the market application of polylactic acid?

Oct 18, 2018

PLA has many applications, which can be applied in many fields such as extrusion, injection molding, film drawing, spinning, etc., as follows:

(1) Extrusion grade resin

Extrusion grade resin is the main market application of PLA. It is mainly used for packaging fresh fruits and vegetables in large supermarkets. This type of packaging has become an important member of the European market chain. Secondly, it is used to promote safe, energy-saving and environmentally friendly packaging of electronic products. on. In these applications, PLA's high transparency, high gloss, high steel and other advantages are reflected, and it is already the leading direction of PLA application. In addition, the application of extrusion grade resin in horticulture has begun to gain attention, and has been applied in the fields of slope greening and sandstorm control.

However, extrusion processing of PLA is not an easy task. It is only suitable for processing on some advanced PET extrusion molding machines, and the thickness of the extruded sheet is generally only in the range of 0.2-1.0 mm. The processing process is particularly sensitive to moisture content and processing temperature. When extruding, it is generally required to have a moisture content of less than 50 PPM, which puts new demands on the drying system and temperature control system of the equipment. In the process of processing, if there is no suitable crystallization equipment, the recycling of the edge material is also a big problem, which is the reason why a large number of PLA scraps are circulating in the market.

(2) Injection molding grade resin

In the market application of PLA injection molding, the modified resin is more widely used. Although pure PLA has the advantages of high transparency and high gloss, its shortcomings such as hard and brittle, difficult to process and not heat-resistant affect its application in injection molding. Of course, the chemical and plastic industries have been working hard to solve these problems. For example, the use of BPM-500 can increase the impact strength of PLA; adding a small amount of a vinyl copolymer called Biomax Strong can improve the toughness of PLA; blending with another biodegradable resin PHA can improve some PLA. Performance; in addition, Japanese scientists have developed a heat-resistant PLA resin with added pulp. The polylactic acid product modified by the above methods sacrifices transparency, but improves the defects of polylactic acid in heat resistance, flexibility, impact resistance, etc., and improves the ease of processing, so the application range is also Has been expanded. About 70% of Hisun's injection-grade resin sales are modified polylactic acid.

On the whole, the relatively high cost is the biggest reason that hinders the widespread use of PLA in the injection molding market. Although pure resin can reduce some costs through filling modification, the effect of this measure is limited under the premise of ensuring its performance. If it is necessary to improve the performance of PLA under the premise of full biodegradation, such as heat resistance. Performance, cost is even higher.

(3) Other grade resins

The biaxially stretched film is the most successful PLA film used so far. The heat resistance temperature of the PLA film which has been biaxially stretched and heat set can be increased to 90 ° C, which just makes up for the defect that PLA is not resistant to high temperature. By adjusting the biaxial stretching orientation and the setting process, it is also possible to control the heat sealing temperature of the BOPLA film at 70 to 160 °C. This advantage is not available in ordinary BOPET. In addition, the BOPLA film has a light transmittance of 94%, a very low haze and a very good surface gloss. The film can be used for flower packaging, envelope transparent window film, candy packaging and the like.

Spunbonded non-woven fabrics have been used in PLA non-woven fabrics. This kind of non-woven fabrics is popular in the production of shopping bags because of the implementation of plastic limiting orders in China. The two areas of blown film and coating are due to some characteristic defects of PLA itself, and the application situation is still being further explored. Some successful application cases are the modification of PLA.

[4] Heart stent

Soluble polylactic acid scaffolds are designed to absorb the benefits of existing instruments without leaving a "metal spider" like a metal scaffold. This "spider image" will appear in the patient's coronary artery when taking X-rays on the patient. Fully bracketed. Existing stents do not contract and do not expand with the natural movement of the artery. Metal stents can cause fatal thrombosis and can interfere with future tests and procedures.