Current progress and development prospect of China’s EDP

By Saizhen Tang and Xin Tao

(Special Committee of Degradable Plastics, China Plastics Processing Industry Association)

Abstract: This article gives a description of current progress of China’s EDP in manufacturing, application, new accessory ingredients, starch modification technique, biodegradable plastics and test evaluation methods and standards. As for the basic trends in development of China’s EDP, this article puts forward the following opinions: the EDP in China must base its development on national situation, and take multiple elements into consideration, such as technology, economy, market, resources environment and etc,; the development of EDP products must be given overall evaluation in their practicability, degradability, security and economical efficiency; the application of EDP must be oriented accurately. The development target of EDP is to reduce environmental pollution and ease environmental contradiction. That is, use replenished and renewable resources as a substitute for nonrenewable resources which are limited and decreasing; develop multi-purpose and biomedical macromolecular materials so as to meet special requirements of market and bring benefit to human being, and of course, ensure the sustainable development of plastic industry accordingly. In the end, the article makes an analysis of development and prospect of China’s EDP market through the viewpoint of environmental protection, resource replenishment and substitution and synthesized materials in high and new-technology.

Key Words:     Resources,      Environment,       Sustainable Development,        Degradable Plastics, Wastes, and Roles

I Development of EDP in China

Research and development of degradable plastics in China started in 1970s. However, it was in 1990s that the degradable plastics came into systematic research and development on certain scale. Especially in these years, the degradable plastics were proceeding to a large extent in their research & development, production, application and in formulation of their standards.

1.    Increasing Varieties, Growing Output and Expanding Field of Appliance

According to the preliminary statistics, there are more than 100 enterprises and institutions in China engaged in research & develop and production of parent materials (special-purpose materials) of degradable plastics. Some products have already been taking the advantage of a system of combined production, education and research. More than 150 twin-screw production lines of parent materials (special-purpose material) have already been set up, with a capacity of nearly 2000 kts. Some enterprises have reached industrial scale in production with products sold in the international market, mainly include the Tianjin Danhai Company, the Nanjing Sushi Company, the Chengdu Zhongrun Company, the Jilin Jinying Company, the Hainan Tianren Company, the Huizhou Huanmei Company, the Jieyang Spring, the Shanghai Jinying, the Shanghai Linda Company, the Shanghai Shenyue Company, the Shantou Jinda Company, the Shijiazhuang Jiebao Company, the Shandong Jiufa Company, the Shenzhen Deshili Company and so on. As most of the products are produced by the existing plastic processing devices, the production capacity is difficult to count.

For several years, with more attention to environmental protection, strengthening environmental protection consciousness as well as consistent advancement of science and technology, the development of degradable plastics in China has formed a good trend of increasing varieties, growing output and expanding field of appliance:

l       By environmental conditions, the degradable plastics researched and development in China can be classified into photo degradable plastics, photo biodegradable plastics, photo-oxygen biodegradable plastics, high-starch content biodegradable plastics, photo-oxygen biodegradable plastics filled with high calcium carbonate, and so on.

l       The output of degradable plastics has been increased to a large extent. According to incomplete statistics, the parent materials (special-purpose materials) was about 40kt in output, with 40% exported; plastic products were 220 kt, with 20% exported.

The new developed application scope of degradable plastics mainly includes agriculture, packaging, daily entertainment products and medical sanitation materials. Degradable plastic products mainly include mulching film, seedling raising plastic bowl, seedling throwing sheet, compost bag, packing film (bag), shrinking film, plastic wrap (bag or box), supermarket shopping bag, packing materials of disposal bags and tableware, cosmetics container, physiological sanitary accessories, baby diaper, non woven, work clothes, tablecloth, glove, beach slippers, spreading materials, golf ball seat and medical materials (such as medical releasing capsule, operation suture, etc). In view of resource replenishment, the purposes of degradable will be further expanded and are of great potential.

2.    Development of New High-Efficiency Photo and Oxygen Degradable Agent

l       The photo degradable plastics developed in China are mainly additive type plastics. After the research and development of photosensitizer and compound photosensitizer of transition metal complex degradable plastics, these years the Environmental Material Development Institute of Fujian Normal University made a in depth research of the degradation technology that plastic products continues to oxidize without light after induced by light, and systematically researched and developed photo degradable polyethylene parent material synthesized by cerium carboxyl or carboxyl terrace rare. This increased the degradation effect of PE degradable plastics to a large degree. This series of compound photosensitizers have been put into industrial production and have been successful in its application for disposal bags, shopping bags, mulching film and tableware. Besides, the institute has researched and developed polyvinyl chloride (PVC) photosensitizer of carboxyl terrace rare. This kind of accessory ingredient may induce PVC photo degradation, and has the effect of continuous oxidation and degradation without exposure of light and to induce the cross linking of PVC in photo. It has been produced in batches, and has been applied to degradable PVC thermal shrinkage film and environmental friendly leisure shoes.

l       To increase thermo oxidizing and degradable capacity of disposable plastic wastes is a research focus in China in recent years. A lot of units are engaged in the research of thermal oxidant. At present, the thermal oxidant has been put into production in batches, and has been successfully applied in the production of disposal bag, wrapping bag, plastic film, shrinking film, rubbish field coverage film, mulching film and so on. Let’s take degradable plastic packaging film in which the controllable degradable additive of 0.1% LTHO is added for example. According to measurement of relevant authoritative departments, its breaking elongation is 452% before degradation, and its sample has been atomized and cannot be measured after 120 hours’ exposure in xenon light.

3.    Great Advancement in Production Technique of Parent Material (Special-Purpose Material) of Starch Base Biodegradable Plastics

The parent material of starch base biodegradable plastics is a key variety for research in China. The modification technique of starch mainly includes surface processing technique, compatible technique, grafting technique and so on. All of these techniques have been advancing to a large extent. The first two have already been put into industrial scale production.

l       The starch surface processing technique is represented by the Tianjin Danhai Company. It has the following technical characteristics: in liquid vacuum hydro extraction, the water content may be decreased to 0.5%; in thinning processing, the grain size of starch may be less than 8m; in hydroxyl modification, the addition level of modified amylum (SMA) is as high as 80% in parent material, 51% in film products, 60 – 70% in injection molded items. According to the measurement (45 days) of the China Taiwan Incorporated Foundation Biological Technical Development Center on the parent material in accordance with ISO14855/CN 14432 (45 days), the rate of biodegradation (released in the form of carbon dioxide) is 52.96% (73.32% for lu paper as control group). Now the company has established a production capacity of 30kt which includes the production of parent materials and products of biodegradable plastics, and has become the largest degradable plastics production base in China as well as in Asia. This project has been decided as the National Technology Industrialization Pilot Project by the Ministry of Planning of the People’s Republic of China. It had the honor to win the international quality golden medal for its products in the Fourth International Quality Conference this year. Its products have been exported to Japan, Australia, Bengal, Chinese Taiwan and other countries and regions.

l       The starch compatible technique is represented by the Nanjing Sushi Company. It has the following technical characteristics: by use of compatilizer modification technology which is mainly finished in twin screw extruder, the technique is relatively simple; starch has a balanced distribution in PE and PP, with good compatibility; products are produced in a manner of special-purpose material, with good processing performance; in film products, the biodegradable content accounts for 60% and starch for 45%. According to the measurement (96 days) of the China Taiwan Incorporated Foundation Biological Technical Development Center on the parent material in accordance with ISO14855/CN 14432 (45 days), the rate of biodegradation is 54.88% (100.81% for cellulose as control group). Now the company has established a production capacity of 10kt. Its products are mainly exported.

l       The grafting technique is researched by many units. Most researches of this technique are small-scale tests. The chemical grafting technique of the Zhejiang University, however, has a better advancement. The film products with 50% starch content are characterized by solid strength, good appearance and moderate price. Its biodegradable performance is still under measurement. At present, it is planned that such products would be put into trial production.

l       The starch thinning technology is one of the key techniques to increase starch content, and guarantee the strength, appearance of products, and lower cost. The technique has gained much progress recently. The new starch cross linking modification technique of China combined with the starch thinning equipment cooperatively developed adopting German technique, has resulted the following characteristics: grain size of starch can be thinned to 6μm (2000 screen mesh) and has a thin distribution; the starch, which has 5% water content, is easy to form film; the oiliness of starch is increased, so that its compatibility with plastics is increased; the thinned starch has no coacervation upon several months’ storage and has a good dispersibility.

4.    Biodegradable Plastics Has Entered into Pilot-scale Phase

In recent years, China has invested many labor forces and physical resources to research and develop biodegradable plastics, including natural macromolecule, microorganism fermenting synthetic macromolecule, and chemical synthetic macromolecule and so on. Most of these researches have been at the pilot-scale phase (see Table 1).

5.    New Progress of Evaluation Methods and Standards for Degradation Performance Test of Degradable Plastics

With the in depth research of degradable plastics and consistent development of their appliance, the evaluation methods and standards of their degradation performance are increasingly important. Many countries have made comprehensive and systematic research on evaluation methods and authentication standards of biodegradation performance test of biodegradable plastics. The International Standards Organization (ISO) and some national institutes (such as ASTM of America, DIN of Germany, CEN of Europe and JIS of Japan) have formulated some test evaluation methods on simulation of natural conditions and established relevant measurement standards and systems respectively. Based on experience of other countries, China has done much on evaluation methods and authentication standards of biodegradable plastics and has made some new progresses.

Table 1        

Survey of Research and Development of Biodegradable Plastics in China

l       Since the end of 1980s, Agricultural Technique Promotion Head Station and Clay Fertilizer Institute of the Ministry of Agriculture of the People’s Republic of China have successively made large-scale farmland overlay film pilot application tests on photo degradable and photo biodegradable mulching films in Xinjiang Province, Shandong Province, Shanxi Province, Heilongjiang Province, Sichuan Province, Yunnan Province, Beijing City and some other districts. Based on these tests, several applied technical indicators have been put forward: The strength of the mulching films meets the requirements of mechanical overlay film; the degradation induction period lasts over 60 days, based on crops of different regions; after using, mulching films can break into pieces smaller than 16cm², to lay a basis for formulation, application and promotion of standards of mulching films.

Table 2 

Standards Formulated and Being Formulated by China on Biodegradable Plastics

l       In the mid of 1990s, the Degradable Plastics Association, China Plastics Engineering Society, together with the Chinese Academy of Agricultural Sciences, the Guangzhou Research Institute of Synthetic Materials and the Shanghai Organic Institute, Chinese Academy of Sciences made field tracking tests on landfill and composting of degradable polyethylene packaging film, photo biodegradable polystyrene food container and ordinary film and box, respectively in Beijing, Shanghai, Guangzhou and other cities. These tests initially obtained useful data. Recently, the China Special Committee of Plastics & Degradable Plastics is making the field test on composting of disposal bags and packaging bags and boxes, together with the Composting Institute of Chinese Academy of Agricultural Sciences, Chinese Academy of Environmental Sciences and other institutes. The test is based on composting test methods and authentication standards in foreign countries and in view of the national situation of China. Now the test is under way.

l       China has formulated relevant standards of degradable plastics several years ago. For these two years, the Biodegradable Materials Standards Group has been established, with the national plastics standardization center as the core, under the joint support of Tsinghua University, Tianjin Danhan Company, Ningbo Tian’an and other institutions of higher learning and large-scale production enterprises. Based on the standards of ISO14851, ISO14852 and ISO14855, the group has formulated a series of evaluation methods and standards of biodegradable materials tests. These methods and standards not only meet the international standards, but also are suitable for the national situation of China. The four national standards/GB (see Table 2) drafted out now are in discussion.

II       Basic pints on the development and Market Prospect of EDP in China

1 Basic pints on the development of EDP in China

China is a developing country with a population of 1.3 billion. It is characterized by large population base, little resources per capita, large amount of environmental problems, as well as economical and technological level lower than developed countries. On the other hand, China is a country with rapid economic development and thriving market demand. This brings heavy pressure on the scarce resources and pressing environment. Therefore, it is of great significance for China to keep economic development and environment protection harmonized, and to implement the sustainable development.

EDP is a kind of plastic product with the function of environment protection. It is a newly developed high-tech material featuring environmental protection. The following basic points on the development of EDP in China are given under the guidance of national policies.

1)    The development must take, based on the national situation, the technology, economy, market and resource environment elements into consideration. Especially the role of price as a lever in the market economy must not be neglected.

2)    The development of degradable plastic products must be comprehensively evaluated in viewpoint of practicality, degradability, security and economical efficiency.

l       Practicability: The degradable plastics should have a performance roughly the same as ordinary plastics of the same kind, and meet their requirement of application.

l       Degradability: Once the value of application is realized, the degradable plastics should degrade into fragments/powders, which can easily dissolve into environment and return to the nature eventually.

l       Security: The derelicts produced during and after the degradation process are harmless, or are of no potential harm to natural environment.

l       Economical Efficiency: The degradable plastics should be close to ordinary plastics of the same kind in price.

3)    Accurate Orientation of Development of EDP: EDP should be used in the natural environment where collection is difficult, or recovery is hardly beneficial, and in the field that is favorable for composting and resource replenishment and substitution, and in medical material field that is favorable for relieving of diseases.

4)    Objectives of Development of EDP: Reducing environmental pollution and relieving/restraining of environmental contradictions; using renewable resources (or resources of rich sources) to replenish and substitute limited nonrenewable resources which are exhausting; developing new high-quality materials to meet special requirements, to bring benefit to people and guarantee the sustainable development of plastics industry.

2 Market Prospect of EDP in China

To sum up, the prospect for development of China’s EDP market should be analyzed in the following viewpoints:

1)    Analysis Based on Environmental Protection

At present, the per capita consumption of plastic products in China is 15kg or so, which is lower than that (158kg) of Germany and Belgium, and also lower than that (19kg) of the world. In spite of that, the environmental pollution resulting from plastic wastes in China has been blamed seriously. With the growth of China’s economy, the per capita consumption of plastics surely will increase. If this situation is not improved and controlled, the load of wastes on environment will be heavier and heavier. Because of its characteristic of easy processing after usage, EDP is a kind of plastic with the function of environmental protection. Disposable plastics, however, are of large pollution scope and are messy, dirty, difficult to collect, and are of little economic benefit or even of negative benefit in compulsory collection. As compared with disposable plastics, EDP can decrease the volume and quantity of wastes, and plays a role in reducing environmental pollution. It is believed a wise choice to develop EDP.

2)    Analysis Based on Resource Replenishment/Substitution

At the end of 20^th century, China’s plastics developed rapidly, mainly because the materials of plastics are based on rich petrochemical industry. With the arrival of the 21^st century, as other places in the world, China will face the problem of exhausting resources. The problem of how to make effective use of resources, save the limited resources and exploit new sources of raw materials, is a significant issue haunting the sustainable development of economy. The high-starch content biodegradable plastics and photo-oxygen degradable plastics filled with high calcium carbonate researched and developed in China at present not only may save 30 – 60% petrochemical resources, but also may reduce the output of wastes to a large extent. Most of biodegradable plastics take renewable resources as source of their raw materials and can enter natural circulation in a short time, so it is the noticeable development trend of resource substitution.

3)    Analysis Based on Synthesized High and New-Technology Materials

The development of biodegradable plastics is of great significance. The significance not only lies in the requirement of environmental protection, but also in that the biodegradable plastics are a new functional and biochemical high molecular material. Because of its physiological adaptability and versatility, the biodegradable plastics have been successfully used in physiological internal decomposition and absorbing material, fracture splint, surgical suture, medical releasing bearer, molding moisture and water absorption material, oxygen resistance material and piezoelectric material and so on. In spite of a low level of usage in these fields, it has a high added value. It can bring benefit to people, so it is of great significance.

4)    Analysis Based on Demand

It is estimated according to relevant departments that China will have a demanded of 5500kt of plastic packaging materials in 2005. If 30% of these materials are disposable plastic materials and products that are difficult to be collected, the wastes will be 1650kt in weight. It is estimated according to the Ministry of Agriculture that the coverage area of mulching film will be 170,000,000 mu in 2005. If mulching film is added with plastic seedling raising bowl, the total demanded of EDP will be 2500kt, which accounts for 10% of the total output of plastics (25,000kt). Therefore, EDP is of great potential in China’s market. In addition, because EDP products researched and developed in China are ensured in quality while featuring a low cost, more and more foreign manufacturers came to China for consultation on trade and cooperation in these two years. Therefore, China’s EDP will be also of great potential in foreign markets.

Though EDP needs further improvement on performance of products and processing techniques, and in spite that there exits some problems and disputes on its development, more than 10 years’ research and application has proven that the development of EDP not only expands functions of plastics and relieves environmental contradiction to a certain extent, but also makes a supplement to exhausting petroleum resource. Furthermore, EDP may synthesize functional and biomedical macromolecule high-tech materials. It meets people’s special requirements and brings benefit to people. It also meets the strategic requirements of sustainable development. Its development is of great significance. Therefore, China’s EDP market has a bright future.

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