According to the source of raw materials, biodegradable plastics include petrochemical-based biodegradable plastics and bio-based biodegradable plastics. The former is produced from coal, petroleum, and natural gas raw materials, mainly including dibasic acid diol copolyester series (including PBAT, PBS, PBSA ), polycaprolactone (PCL), polyglycolic acid (PGA), polyvinyl alcohol (PVA) and CO2 copolymer (PPC), etc.; the latter is produced from biomass raw materials, mainly polylactic acid (PLA), polyhydroxyl Fatty acid esters (PHA), all starch-based materials, cellulose materials, etc.
1. Bio-based biodegradable plastics
Natural polymer material biodegradable plastic
The natural polymer raw materials of biodegradable plastics come from plants and animals. Plant sources include starch, cellulose, lignin and their derivatives, and animal sources include gelatin, chitin, acetylated chitin, chitosan and its derivatives, etc. Modification of natural polymer materials to make them thermoplastic is the main method for preparing natural polymer materials biodegradable plastics.
In the 18th century, celluloid was the earliest example of using natural polymers to make plastics by digesting cellulose as a raw material.
PLA
The raw material of PLA is lactic acid, which is mainly synthesized from biomass resources such as corn starch, and is a representative of bio-based biodegradable plastics.
There are three main ways to synthesize PLA: one is the direct condensation of lactic acid; the second is to synthesize lactide into lactide, and then catalyze ring-opening polymerization; the third is solid-phase polymerization. Most of the domestic synthetic routes of PLA are based on the second route.
PHA
PHA is a polyhydroxyalkanoate, as a new type of fully biodegradable thermoplastic, with biocompatibility, biodegradability, and animal edibility.
PHA is a large family of materials, more than 150 different monomer structures have been discovered, but only a few have actually been produced on a large scale. At present, foreign companies producing PHA mainly include Japan's Kaneka Company, Brazil's Biocycle Company and Germany's Biomers Company. There are Ningbo Tianan Biomaterials Co., Ltd. and Tianjin Guoyun Biotechnology Co., Ltd. in China.
2. Petrochemical-based biodegradable plastics
Dibasic acid diol copolyester
Dibasic acid diol copolyesters include polyadipate/butylene terephthalate (PBAT), polybutylene succinate (PBS), polybutylene succinate-adipate (PBSA) ). Although PBS and PBSA were developed earlier, due to their own performance limitations, the market usage is less than that of PBAT. Currently, global production is dominated by PBAT.
The domestic enterprises producing PBAT mainly include Guangzhou Kingfa Technology, Shandong Huiying New Materials, Shandong Yuetai, Xinjiang Lanshan Tunhe Polyester Co., Ltd., Jinhui Zhaolong High-tech Co., Ltd., Hangzhou Yifan Xinfu Pharmaceutical Co., Ltd. .
Carbon dioxide copolymer (PPC), polycaprolactone (PCL)
Other petrochemical-based biodegradable plastics include PPC, PCL, etc.
3. Application areas
According to the application field, the main uses of biodegradable plastics are textile fibers, packaging, agriculture, forestry, fishery and animal husbandry, automobiles, 3D additive materials, etc.
textile fiber
The current production capacity of PLA fibers in my country is about 15 kt/year. It combines the advantages of natural fibers and synthetic fibers, and because of its excellent wicking properties, its products have the characteristics of good resilience, strong drape, and high comfort.
Daily film, bag
Biodegradable plastic film bags are mainly PBAT, and most of them are blended with PLA and other materials. After processing, they have begun to be applied on a large scale in household garbage bags, plastic shopping bags, daily plastic bags, etc., and are also used in fresh packaging films. . In addition, PLA-based biaxially oriented film is used as a fresh-keeping film, which has excellent fresh-keeping effect on vegetables and fruits.
Sheets and their thermoformed products
After the PLA extrusion sheet is thermoformed, it has begun to be used in the packaging of fresh food, salad, food, etc., such as fruit transparent boxes, egg boxes, etc.
Agricultural mulch
The annual demonstration amount of biodegradable plastic film in Xinjiang, Gansu, Hubei, Yunnan and other provinces and cities has exceeded 100,000 mu. The main manufacturers of biodegradable plastic film are Kingfa Technology Co., Ltd., Hangzhou Xinfu Technology Co., Ltd., etc.
foam products
PLA foam products have been used in many supermarkets for packaging dishes and boxes for fresh food and vegetables. Starch-based plastics and PLA foam cushioning materials are used in the packaging of electrical and electronic machines and precision machinery.
In addition, biodegradable plastics have also been used in auto parts and 3D printed products.
