First, the development trend of degradable plastics

In recent years, developed countries such as Europe, the United States and Japan have invested a large amount of funds in the research and development of biodegradable plastics, and have accelerated the pace of industrialization in an attempt to seize the dominant position in the future market competition. Europe's first priority - At present, the United Kingdom has begun to promote the use of starch series, polylactic acid series of biodegradable shopping bags and food packaging bags in supermarkets, and the annual consumption can reach 20 billion. In 2003, the Italian biodegradable plastics market was about 120,000 tons. BASF has launched a biodegradable plastic product under the trade name “Ecoflex” with an industrial capacity of 30,000 tons/year and its factory is based in eastern Germany. The Dutch company Rodenburg Biopolymers is becoming the new leader in the biodegradable plastics market in Europe. Its production capacity has reached 40,000 tons/year and it plans to open more new factories in France, North America and Asia after 2005. The first is to reduce the product to the same level as ordinary plastic within two years. After the United States came first, the United States, as a technologically advanced industrial power, is not far behind in the development of biodegradable plastics that are of great significance for sustainable economic development. Currently, there are more than a dozen development organizations and manufacturing companies, of which Gargill Dow is At present, the world's largest biodegradable plastics industrialization production company, the main production of polylactic acid series of biodegradable plastics, has now completed a 14 million tons / year scale of production capacity. Japan Corn Starch Co., Ltd. established a joint venture with U.S. to establish a starch series biodegradable plastics plant with a production scale of 20,000 tons/year; Japan Chemical Corporation's trade name “Lacea” biodegradable resin is used as agricultural film and composting bag in 2002. It has reached a scale of 30,000 tons; Showa Polymer Co., Ltd.'s chemical synthesis of aliphatic polyester industrial scale will reach 100,000 tons / year.

China's development of degradable plastics is also very necessary, and it also has broad prospects for development. According to the forecast of related departments, in 2005, the demand for plastic packaging materials in China will reach 5 million tons. According to 30% of the disposable plastic packaging materials and products that are difficult to collect, the amount of waste generated will reach 1.5 million tons; China can cover plastic film. With an area of ​​500 million mu, the estimated demand for nursery stocks and agricultural and sideline products will reach 1 million tons; some of the disposable sundry goods and medical materials are also difficult to collect or are not suitable for recycling. Up to 1 million tons. As a result, the waste of plastics that are difficult to recycle will reach 3.5 million tons, and the resulting environmental problems will become increasingly serious. If 50% of them are replaced by biodegradable plastics, the demand for biodegradable plastics will reach 1.75 million tons. If it cannot be properly recycled or degraded, it will cause serious pollution and harm to the ecological environment of rural areas and cities. . Therefore, biodegradable plastics have great potential in the Chinese market.

Second, the problems and development trends of degradable plastics

Degradable plastics, a brand-new technological approach to the management of plastic waste, has achieved satisfactory progress after years of research and development. Of course, although photodegradation and photo-biodegradable plastic products are simple to process and low in cost, they are difficult to control when they are degraded. They are not suitable for entering landfill systems. Starch-filled degradable plastics are difficult to process and their performance is not ideal. Fully biodegradable plastics have good degradation performance, but they are difficult to process, expensive, and sometimes controlled to degrade. The problem of comprehensive composting is needed after use. In addition, a more reasonable process recipe for degradable plastics, recycling of scraps, etc. Technical issues need to be further improved and improved. Although there are still many problems in the degradation of polymer materials, due to the progress of degradation technology, related problems are gradually being solved and the market prospects are getting better and better. In order to make the degradable plastic technology have greater development on the basis of greater achievements, from the perspective of development trends, there are the following aspects of the problem worth further discussion and research in the future.

1. The practicality of degradable plastics such as disposable plastic film, packaging materials and tableware

Degradable plastic products such as disposable plastic film, packaging materials, and tableware can be used for practical research by adopting the comprehensive degradation technology of controlled photo-oxygen-biodegradable plastics filled with edible starch or inorganic minerals. The area of ​​China's coverable plastic film is 500 million mu and the dosage is up to 400,000 tons. It is more suitable to use low-cost photo-oxygen-biodegradable plastic mulch, and the degradable plastic film with thickness of 0.005mm-0.015 mm can also use plastic photo-oxygen degradation technology alone. , but it must be done to control the degradation. Such as the Chinese Ministry of Agriculture and the General Assembly of Light Industry led the development of technical standards for degrading mulching films or countries and industries, and organized and promoted them in a planned manner. This has profound implications for solving the problem of abandoned farmland polluting farmland and benefiting future generations. For degradable plastic products such as shopping bags, food, sundries bag materials, and tableware, the degradation characteristics must meet HJBZ 12-2000 “Technical Requirements for Environmental Labeling Products of Packaging Products”, QB/T 2461-1999 “Degradation polyethylene film for packaging. "GB 18006.1-1999 "General technical conditions for disposable degradable tableware", HBC 1-2001 "Technical Requirements for Environmental Labeling Products for Disposable Tableware". Moreover, it must be stressed that it is not possible to discard it at will, but it is also mandatory to recycle, regenerate or incinerate the recovered energy.

2. Researching fully biodegradable plastics is an important development trend of degradable plastics

From the point of view of protecting ecological balance, it is urgent to study completely biodegradable plastics. In particular, biodegradable plastics that are simple in synthesis method, reasonable in processing process, and low in cost are an important research topic for biodegradable plastics. Non-returnable medical plastic products such as sewing needles, sutures, syringes, infusion bags, garbage bags, compost bags, pesticide bottles, cosmetics containers, diapers, and sanitary napkins for women should be used at a low cost. Biodegradation technology. For products such as garbage bags, compost bags, fertilizer bags, etc., high-quality, lower-cost, fully biodegradable plastics filled with starch or inorganic minerals can be studied to meet the needs of the market.

3. Use natural recyclable degradable materials as much as possible

According to the latest research report of the International Biodegradable Polymers Association (IBAW), between 2001 and 2003, the use of biodegradable plastics worldwide has doubled, and the total use has risen to 40,000 tons/year. IBAW states that although this figure also includes petroleum-based biodegradable materials, petroleum resources are now becoming increasingly scarce. As long as the technology permits, producers will use natural, recyclable materials as much as possible. Biodegradable plastics currently made from starch and vegetable oils have dominated the market. Recent surveys conducted in several countries show that consumers are very interested in this type of packaging material, and more interestingly, consumers are willing to pay more for this. Recently, a survey conducted by the American market research institution Grapentine Company found that 41% of American consumers and 59% of European consumers are very eager to buy foods made of natural biodegradable plastic packaging. About 77% of European consumers are willing to pay 5 cents more for this, and 74% of American consumers are willing to pay 10 cents more. IBAW predicts that the share of natural biodegradable plastics in the biodegradable plastics market will continue to rise, especially under the current high oil prices.

4. Thermoplastic starch resin is a kind of fully biodegradable plastic that is currently the most promising

The starch molecules are allosterically and disordered to form a thermoplastic starch resin, followed by a small amount of additives such as plasticizers, so-called full starch plastics. The starch content is above 90%, and the small amount of other substances added are also non-toxic and can be completely degraded, so the whole starch is truly a fully degradable plastic. Almost all plastic processing methods can be applied to the processing of whole starch plastics. All-starch plastic is currently the most promising biodegradable plastic at home and abroad. Sumitomo Corporation of Japan, Wanler lambert of the United States and Ferruzzi of Italy announced that they have successfully developed full-starch plastics with a starch content of 90% to 100%. The product can be completely biodegraded within 1 year without leaving any traces and no pollution. In the manufacture of various containers, films and garbage bags. The Battelle Research Institute in Germany developed a biodegradable plastic with modified green pea starch with a high linear content, which can be processed and formed by conventional methods. As a substitute for PVC, it can be completely degraded in a moist natural environment.

5. Carbon dioxide-based biodegradable plastics are currently research projects with broad development prospects

Japan's Inoue has found that carbon dioxide can undergo ring-opening polymerization with epoxides to form aliphatic polycarbonate (APC), which is the most promising CO2 copolymer to date. Takanashi et al. used a terpolymer of carbon dioxide, propylene oxide, and an ester-containing epoxide as a drug release agent. Masahiro et al. used the method of evaporating solvent to prepare PPC microspheres as the carrier of the drug sustained-release system, and studied the influencing factors of the release rate of the system, such as the molecular weight of PPC and the drug content. The results showed that with the decrease of the diameter of the microspheres or the increase of the drug concentration, the drug release rate increased, but the drug release rate and biodegradability were independent of the molecular weight of the copolymer. The morphology of the microspheres before and after drug release was observed by SEM, and the PPC was confirmed. Microspheres support long-acting, uniform release of drugs. U.S. experts adopted a new technology that uses special zinc catalysts to mix and copolymerize carbon dioxide and ethylene oxide (or propylene oxide) in a certain proportion to produce plastic packaging materials with new features. The carbon dioxide-based fully biodegradable plastics project implemented by China Jilin Group Corporation and the Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, has been included in the National 863 Research Program. It is a new high-tech environmental protection material research and development project with broad development prospects.

6. Definition of degradable plastics and evaluation methods are the basis for the promotion of degradable plastics

However, the world’s developed countries, especially the United States, have also done a lot of research. At present, ASTM has announced the following test standards: Biodegradable plastics related evaluation test standards, ASTM D5209-92, ASTM D5210-92, ASTM D5247-92, ASTM D5271-92, ASTM D5338-92. Photodegradable plastics related evaluation test standards, ASTM D5071-91, ASTM D5208-91, ASTM D3826-92. Environmental safety related evaluation test standard, ASTM D5152-91. At present, China has published the relevant test standards are as follows: GB 18006.1-1999 "General technical conditions for disposable degradable tableware", GB/T 18006.2-1999 "Test method for degradation performance of disposable degradable tableware", HJBZ 12-2000 “Technical Requirements for Environmental Labeling Products of Packaging Products”, HBC 1-2001 “Technical Requirements for Environmental Labeling Products for Disposable Tableware”, QB/T 2461-1999 “Degradation polyethylene film for packaging”. In the future, reference will still be made to the relevant test standards of developed countries and China, combined with the market promotion of various types of degradable plastic products, and the research on the definition and evaluation methods of degradable plastics will be in-depth. The relevant test standards will be continuously improved and improved. This is the promotion of degradable plastic products. The foundation and industrialization of the premise.

Third, the Olympic Games, the World Expo, etc. for the use of biodegradable plastic enrich vitality

The Olympic Games will consume a lot of plastic materials, and the whole biodegradable plastic