Biodegradable plastic refers to a type of plastic that is degraded by the action of naturally occurring microorganisms such as bacteria, mold (fungi) and algae. An ideal biodegradable plastic is a polymer material that has excellent performance, can be completely decomposed by environmental microorganisms after being discarded, and is eventually inorganized to become an integral part of the carbon cycle in nature. "Paper" is a typical biodegradable material, while "synthetic plastic" is a typical polymer material. Therefore, biodegradable plastics are polymer materials that have the properties of both "paper" and "synthetic plastics". Biodegradable plastics can be divided into two types: completely biodegradable plastics and destructive biodegradable plastics.
Destructive biodegradable plastics: Destructive biodegradable plastics currently mainly include starch-modified (or filled) polyethylene PE, polypropylene PP, polyvinyl chloride PVC, polystyrene PS, etc.
Completely biodegradable plastics: Completely biodegradable plastics are mainly made from natural polymers (such as starch, cellulose, chitin) or agricultural and sideline products through microbial fermentation or synthesis of biodegradable polymers. Such as thermoplastic starch plastic, aliphatic polyester, polylactic acid, starch/polyvinyl alcohol, etc. are all such plastics.
Current status and development trends of biodegradable plastics at home and abroad
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Based on the classification of raw materials, biodegradable plastics have at least the following types:< /p>
1. Polycaprolactone (PCL)
This plastic has good biodegradability and its melting point is 62°C. The microorganisms that break it down are widely distributed under aerobic or anaerobic conditions. As a biodegradable material, it can be mixed with starch and cellulose materials, or polymerized with lactic acid.
2. Polybutylene succinate (PBS) and its polymers
Use PBS (melting point: 114°C) as the basic material to manufacture various high molecular weight Polyester technology has reached the level of industrial production. Japan's Mitsubishi Chemical and Showa Polymer Corporation have begun industrial production, with a scale of about 1,000 tons.
The Institute of Physics and Chemistry of the Chinese Academy of Sciences is also conducting research on the synthesis of polybutylene succinate*** polyester. Currently, the Institute of Physics and Chemistry of the Chinese Academy of Sciences is preparing to build a PBS production line with an annual output of 10,000 tons, and Guangdong Kingfa Company has built a production line with an annual output of 1,000 tons.
3. Polylactic acid (PLA)
The American company Natureworks has done active and effective work in improving the production process of polylactic acid, and developed the method of fermenting glucose from corn to produce polylactic acid. , the annual production capacity has reached 14,000 tons. The Japanese company UNITIKA has developed and produced many kinds of products, among which canvas, trays, tableware, etc. were widely used at the Aichi Expo in Japan.
my country's current industrialized companies include Zhejiang Haisheng Biodegradable Plastics Co., Ltd. (5,000 kiloton/year production line), and units currently undergoing pilot trials include Shanghai Tongjieliang Biomaterials Co., Ltd. and Jiangsu Jiuding Group. wait.
4. Polyhydroxyalkanoate (PHA)
At present, the United States and Brazil are the main countries that have achieved industrial production abroad. At present, domestic production units include Ningbo Tianan Biomaterials Co., Ltd. (scale: 2,000 tons/year), and units undergoing pilot trials include Jiangsu Nantian Group Co., Ltd., Tianjin Guoyun Biotechnology Co., Ltd., etc.
Using biodegradable plastics obtained from renewable resources, mixing aliphatic polyester and starch together, the technology to produce degradable plastics has also been successfully researched. In European and American countries, mixtures of starch and aliphatic polyester are widely used to produce products such as garbage bags. The largest and best-selling company in the world is the Italian Novamont company, whose trade name is Mater-bi. The company's products are widely used in Europe and the United States.
There are many domestic research and production units, among which the industrialized units include Wuhan Huali Technology Co., Ltd. (scale 8,000 tons/year), Zhejiang Huafa Ecological Technology Co., Ltd. (8,000 tons/year), Zhejiang Tianhe Ecological Technology Co., Ltd. (5,000 tons/year), Fujian Best Biomaterials Co., Ltd. (scale: 2,000 tons/year), Zhaoqing Huafang Biodegradable Plastics Co., Ltd. (scale: 5,000 tons/year), etc.
5. Aliphatic aromatic random polyester
The monomer of aliphatic aromatic random polyester (Ecoflex) manufactured by BASF in Germany is : Adipic acid, terephthalic acid, 1,4-butanediol. The current production capacity is 140,000 tons/year. At the same time, biodegradable plastic products based on polyester and starch were developed.
6. Polyvinyl alcohol (PVA) biodegradable plastics
For example, Italy's NOVMANT's MaterBi product in the 1990s mainly added PVA to starch, which can blow films. Other products can also be processed. Polyvinyl alcohol materials need to undergo certain modifications to have good biodegradability. The Light Industrial Plastics Processing and Application Research Institute of Beijing Technology and Business University has achieved certain results in this regard.
7. Carbon dioxide polymer
Abroad, the earliest countries to study carbon dioxide polymers were mainly Japan and the United States, but there has been no industrial production.
Domestic Inner Mongolia Mengxi Group Company adopts the technology of Changchun Institute of Applied Chemistry and has built a device with an annual output of 3,000 tons of carbon dioxide/epoxy compound polymer resin. The products are mainly used in packaging and medical materials. superior. The low molecular weight carbon dioxide polymer technology developed by Dr. Chen Liban of the Guangzhou Institute of Chemistry, Chinese Academy of Sciences has been put into production in Taixing, Jiangsu Province. The variety is low molecular weight carbon dioxide/epoxy compound polymer, which is used as polyurethane foaming material. Raw materials used for packaging of household appliances, etc. Using the technology of Professor Meng Yuezhong of Sun Yat-sen University, Henan Tianguan Group has built a pilot-scale carbon dioxide polymer production line and is expected to launch pilot production this year.
Others such as chitin, polyamide, polyaspartic acid, polysaccharide, cellulose, etc. are all under development.
Development status and trends
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According to data from the Japan Biodegradable Plastics Research Association, Japan’s biodegradable plastic production volume in 2002 was approximately 1 million tons, about 20,000 tons in 2003, about 40,000 tons in 2005, and is expected to reach about 100,000 to 200,000 tons by 2010.
According to the European Bioplastics Association, figures in 2001 show that the consumption of biodegradable products in the EU was 25,000 to 30,000 tons, while the consumption of traditional polymers was as high as 35 million tons. The European Bioplastics Association predicts that the consumption of traditional polymers will reach 55 million tons in 2010, while the consumption of biodegradable plastics will reach 500,000 to 1 million tons. Biodegradable materials may eventually capture 10% of the market. The proportion of renewable resources used in biodegradable materials will account for more than 90%.
According to statistics from the Degradable Plastics Professional Committee of the China Plastics Association, the amount of biodegradable materials used in my country in 2003 was about 15,000 tons, of which about 1,000 tons were biodegradable polymers without added starch. In 2005, there were about 30 companies engaged in biodegradable plastics, with a production capacity of 60,000 tons/year, actual production of about 30,000 tons, domestic market demand of about 50,000 tons, foreign imports of 10,000 tons, and exports of 20,000 tons. It is expected that the production capacity will reach about 250,000 tons in 2010.
Domestic and foreign policies
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Some developed countries also use degradable disposable utensils under the guidance of circular economy ideas, such as Sweden in In the late 1980s, disposable fast food boxes made of potatoes and corn were trial-produced, and South Korea made it mandatory by law to use toothpicks made of glutinous rice. Europe has formulated the standard EN13432 "Requirements for testing and final evaluation of packaging that is conducive to composting and biodegradation for recycling" regarding biodegradable compostable plastics, while other decrees related to promoting the composting treatment of organic waste are actively being formulated and prepared. The U.S. government has established the President's Green Chemistry Challenge Award since 1996 to encourage the development of the biodegradable plastics industry. New York State began to ban the use of non-biodegradable vegetable bags in 1989, subsidize manufacturers that produce degradable plastics, and require citizens to separate recyclable and non-renewable garbage, otherwise they will be fined $500.
Some other countries have also adopted similar countermeasures: India has legislated to ban the use of plastic packaging in the dairy industry; South African law has completely banned the use of plastic packaging bags. With the development of legislation in various countries, new biodegradable packaging materials are expected to become increasingly popular.
In our country, with the deepening of the understanding of degradable plastics, the strategic role of this material and its industry in the sustainable development of our country has been fully realized. The popularization and application of biodegradable plastics has been widely expected. In 2004, the National People's Congress of my country passed the "Renewable Energy Law (Draft)" and the "Solid Waste Law (Revised)" to encourage the use of renewable biomass energy and the promotion and application of degradable plastics. In Document No. 40 of 2005 by the National Development and Reform Commission, it was also clearly stated that the use and promotion of biodegradable plastics should be encouraged. In 2006, the National Development and Reform Commission launched a special fund project to promote the development of biomass biodegradable materials.
Problems and difficulties faced by the development of biodegradable plastics
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However, although there are many studies and reports on degradable plastics, Many specific problems cannot be solved, promotion is extremely difficult, and the prospects are not optimistic. The reasons are: First, because the load-bearing capacity of degradable plastic bags is low, they cannot meet the requirements of customers for loading more items and repeated use; second, the color of degradable plastic bags is dull and yellow, and their transparency is low, giving people a sense that they are not clean enough and ugly. , it is not safe to use; thirdly, the price is on the high side. Since the merchant gives it away for free, the cost is difficult to accept.
Another example is to solve the environmental pollution problem of EPS fast food lunch boxes. Try using paper lunch boxes or biodegradable plastic lunch boxes instead. However, it is extremely difficult to promote due to the following reasons: First, EPS has high strength, light weight, and good thermal insulation; second, the price of paper lunch boxes is 1.5 to 2.5 times that of EPS; third, even if degradable PP lunch boxes are used, their performance is not as good as that of EPS. on EPS. Recently, relevant departments in my country require the use of plant fibers to make disposable tableware instead of EPS. However, since polymer hot melt is used in the molding process of this kind of plant fiber tableware, there are still problems with handling and controlling the content of pesticides remaining in the plant fiber tableware.
Therefore, there is still a long way to go to develop and study degradable plastics.
Policies and measures for industrial development
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(1) Accelerate product application research, development and industrialization
At present, the performance of biodegradable plastic products cannot fully meet consumer needs. Although there are many varieties on the market, the mechanical and processing properties of each material only have outstanding characteristics in one aspect, and the overall performance is still as follows Or such shortcomings will be one of the bottlenecks restricting its market application and promotion. While developing biodegradable plastic products, domestic companies should pay attention to accelerating the development of innovative products and uses with independent intellectual property rights. Because the research, development, production and application of biodegradable plastic products in foreign countries are relatively early and many patents have been applied for, this has created certain technical barriers for domestic companies to develop new products. Take the patent of polylactic acid as an example. In 2005, there were more than 1,700 foreign patents related to polylactic acid, while there were only 145 patents published in my country, and more than half of them were patented by foreign companies. Therefore, domestic enterprises should strengthen the development of products with independent intellectual property rights.
(2) Strengthen product processing development research
Secondly, the current domestic strength in product processing research is still weak. Most companies focus on material synthesis, while Ignoring product processing and development, some tableware made of biodegradable plastics are far from traditional plastic products in terms of heat resistance, water resistance and mechanical strength. This is precisely the key to the large-scale marketization of biodegradable plastics.
(3) Improve the garbage recycling and processing system and promote the reuse process of biodegradable plastics
The lack of a complete recycling and processing system also restricts the further promotion of products. Therefore, degradable plastics must be clearly labeled and recycled. Those that can be reused should be collected and then molded and processed into products; those that cannot be reused should be properly disposed of. For degradable plastics that add renewable resources such as starch to traditional plastics, a waste treatment system with thermal energy recovery can be used. For biodegradable plastics, composting should be considered.
(4) Accelerate the formulation of relevant policies and regulations
1. Special financial support
Adopt subsidy policies for the application and development of biodegradable plastic products, including central Government subsidies and local government subsidies. The central government can provide subsidies through scientific and technological research funds, interest subsidies, etc., such as the demonstration and promotion of disposable biodegradable plastic products in the Olympic Games.
The state can consider adopting low-interest loan policies, special loans for technological transformation, and credit guarantee policies for companies that use biomass raw materials to produce biodegradable plastics to encourage industrial development.
2. Tax policy
Currently there are no explicit provisions on low tax rates for the import of biodegradable plastic products. In order to promote the development of the industry, preferential tariff rates should be formulated.
In order to encourage and support the development of some enterprises, preferential policies for exemptions and reductions can be provided in accordance with the new corporate income tax regulations, such as: First, enterprises in ethnic regional autonomous areas need to be cared for and encouraged, with the approval of the provincial people's government , regular tax reductions and exemptions can be implemented; second, enterprises that are granted tax reductions and exemptions by laws, administrative regulations and relevant provisions of the State Council shall implement them in accordance with the regulations.
3. Strengthen the recycling and reuse of traditional plastics and increase recycling taxes
Foreign countries attach great importance to the recycling and reuse of plastic products after use. For example, according to the European Commission’s revised guiding law , EU member states should increase the reuse rate of their own packaging waste to more than 55% between 2008 and 2015, of which the reuse rate of glass packaging reaches 60%, metal packaging reaches 50%, plastic packaging reaches 22.5%, and wooden packaging reaches 22.5%. Reach 15%. The European Commission pointed out that in 2001, the reuse of packaging waste alone reduced EU carbon dioxide emissions by 0.6%, which shows that increasing the reuse rate of packaging waste can not only reduce the energy consumption of packaging materials, but also save the cost of building incineration treatment plants. , and can reduce the environmental pollution caused by the production process of packaging materials. It is a very practical and effective measure to reduce greenhouse gas emissions and protect the environment. Therefore, the mandatory recycling of traditional plastics must be strengthened. For disposable plastic packaging products with high recycling costs, an additional recycling tax of 10% to 100% will be charged. For disposable plastic packaging products that cannot be recycled, biodegradable plastics must be used.
There is a long history of taxing traditional plastic disposables abroad. In March 2002, the Irish government began to levy a value-added tax on plastic bags. According to the Irish government's regulations, customers will be charged a tax of 15 euro cents for each plastic bag used when shopping in the market. The number of plastic bags used in Ireland is staggering. As many as 1.2 billion plastic bags are distributed to shoppers for free every year, weighing a total of 14,000 tons. Divided evenly, each person consumes about 325 plastic bags a year on average. Within one month after the value-added tax on plastic bags came into effect, the consumption of plastic bags dropped by more than 90%.
4. Appropriately restrict certain disposable non-degradable packaging products made of traditional plastics
Appropriately restrict or even ban certain disposable non-degradable packaging products made of traditional plastics in phases. Such as disposable garbage bags, shopping bags, daily necessities outer packaging, disposable fast food containers, disposable plastic cups, disposable food packaging containers, disposable food packaging films, disposable industrial packaging, etc.
5. Promote degradable plastics in phases and in batches
Gradually promote the promotion of degradable plastics in accordance with industry production capacity and product production technology. Before 2010, the main line was to promote biodegradable plastics, supplemented by natural materials such as starch and mixed with traditional plastic products. Policy support was given to these two types of products, but the former was stronger than the latter. After 2010, biodegradable plastics will be fully promoted, and traditional plastic products with starch added will no longer enjoy preferential policies.
6. Strengthen the bridging role of industry associations
Strengthen the industry bridging role of the Degradable Plastics Professional Committee of the China Plastics Processing Industry Association, provide financial support to industry associations, and use industry associations to strengthen investment in enterprises , production direction, product positioning, etc., promote exchanges within and outside the industry, promote domestic and foreign exchanges and trade, as well as sufficient policy research and industry statistics, etc.