Present Development Status and Projection of Biodegradable Plastics    

Petrochemical products can be seen everywhere today. They have brought conveniences to human and also produce hazards to environment.
   Raw materials for biodegradable plastics are usually plant fiber and starch. The outstanding feature of such plastics is very little pollution. They can be easily degraded into water and carbon dioxide and the emission of carbon dioxide in their whole production and application cycle is around 30% lower than oil-based plastics.

  1. Major products

Products that have already achieved commercial production today include polylactic acid (PLA), modified starch plastics and polyhydroxybutyric valerate (PHBV). Besides, polycarbon dioxide plastics with carbon dioxide as raw material is counted in.

PLA
Starch is used to produce lactic acid through fermentation and polymerization is then conducted to produce polylactic acid. Most of polylactic acid units in China are pilot units only with a capacity of several thousand or even several hundred tons a year. Through constant technical innovations, the ex-factory cost of polylactic acid has been reduced significantly. Shanghai Tong-Jie-Liang Biomaterials Co., Ltd. claims that the ex-factory cost of its products is around RMB10 000 per ton, close to the price of chemical plastics particles.

Modified starch plastics
Modified starch plastics are produced through starch modification and then graft polycondensation with selected polymers. The content of starch in modified starch plastics produced by Wuhan Huali Environmental Protection Science & Technology Co., Ltd. can reach 50% - 70%. Owing to the great consumption of starch, the production cost is more than 30% lower than products totally using polylactic acid and there is therefore greater cost advantage.

Carbon dioxide plastics
Carbon dioxide plastics are produced through the copolymerization of carbon dioxide with other compounds in presence of catalyst. Varieties that have started large-scale production include carbon dioxide/propylene oxide copolymer, carbon dioxide/propylene oxide/ethylene oxide ternary copolymer and carbon dioxide/propylene oxide/epoxy cyclohexane ternary copolymer.

Other biodegradable plastics
Besides the above-mentioned varieties, there are also PHA, PHBV and PBS.

  2. Production

The total capacity of biodegradable plastics in China is around 80 000 t/a today and the output is 20 000-30 000 tons a year. Products include PHA, PLA, PCL and modified starch. The biggest producer of biodegradable plastics in China is Tianjin Sitaili Atitude Favourable Degradative Plastics Co., Ltd. Its products include starch-extended biodegradable plastics, starch-based biodegradable plastics, photo/biodegradable plastics and environment degradable plastics. The capacity has already reached 30 000 t/a. (CCR2000, No. 27) The capacity in Jilin Golden Eagle Industrial Co., Ltd. has also reached 10 000 t/a. The 10 000 t/a corn-based plastic project in Hebei Dongguang Donghua Co., Ltd. started production in early 2007. The capacity is 7 000 t/a in Nanjing Sushi Degradable Resin Chemical Co., Ltd., 5 000 t/a in Zhejiang Hisun Group, 3 000 t/a in  Inner Mongolia Melic Sea High Tech Group Company and 2 000 t/a in Ningxia Huaxi Degradable Plastic Products Co., Ltd. Enterprises with a capacity of 1 000 t/a include Shenzhen Deshili Group (China) Co., Ltd., Shenzhen Greenplas Co., Ltd., Huizhou Huanmei Degradable Resin Products Co., Ltd. and Hainan Tianren Degradable Resin Co., Ltd., totaling around 80 000 t/a. Most of these enterprises have passed the environmental protection symbol certification of the state. They have stable product quality and hold a leading position in the domestic degradable plastic market.
   Besides above-mentioned units, the total capacity of projects planned for construction is more than 200 000 t/a. Project undertakers include Qinhuangdao Lihua Starch Co., Ltd. (4 000 t/a polylactic acid), Zhejiang Hisun Group (50 000 t/a polylactic acid), Shanghai Tong-Jie-Liang Biomaterials Co., Ltd. (30 000 t/a polylactic acid), Henan Piao'an Group (10 000 t/a) and Jiangsu Jiuding Group (page 10, 13).

  3. Consumption

The consumption of biodegradable plastics in the world was around 84 000 tons in 2005, three times the consumption in 1998 and the average annual growth was more than 25%.
   The consumption in China is relatively small. The main reason is the high price. A considerable portion of domestic products is exported to overseas markets. The central government and local governments have paid greater attention to environmental protection in recent years and also formulated some regulations on restricting the application of non biodegradable plastics in some sectors such as food packing and disposable tableware. It is expected that with the implementation of laws and regulations on environmental protection the consumption of biodegradable plastics will have a rapid increase in the next few years. Besides, the oil price rise in the international market has also pushed the price of oil-based plastics. The price of imported PE is RMB11 800-12 500 per ton and the price of imported PS is also RMB10 900-11 500 per ton in 2007, already close to the price of polylactic acid.