Review of recycling of plastic packaging material waste in various countries (5)

4.5 Degradable Plastics

The research and development of degradable plastics can be traced back to the 1970s. At that time in the United States, the use of plastic beverage bottles to lift rings and discarded fields after the use of agricultural films not only affected the appearance of the environment, but also endangered the life of wild animals, and were thus condemned and crusade by the environmental protection department. . For this reason, research on photodegradable plastics was carried out. In the 1980s, starch-filled “biodegradable plastics” were researched and developed, and they were blown up to be rapidly biodegradable under the influence of microorganisms in landfills or soils. The market was all the rage, but after years of practice, this material has been accused of exaggerating propaganda, false propaganda, and strong opposition from the environmental protection department for failing to obtain a convincing biodegradable effect. Degradable plastic technology has made great progress since the 1990s, and developed many new varieties such as light/biodegradable plastics, photothermal degradable plastics, starch blended degradable plastics, water-soluble degradable plastics, and completely biodegradable plastics. Since entering the 21st century, biodegradable plastics, especially biomass plastics, have met the principles of environmental protection and sustainable development and have received greater attention and further development.

Although the degradable plastics have made great progress, in general, the degradable plastics technology needs to be further improved and perfected. The performance needs to be further improved and the cost needs to be further reduced. Its role in the environment should be properly evaluated.

Degradable plastic is a member of the plastics family. It is required to maintain or have the characteristics of ordinary plastics before use, and after use, it requires rapid degradation under natural environmental conditions. Stability and degradation are a contradiction. It is achieved at different stages of the same product, and it is very difficult and it is a high-tech product.

Degradable plastic Because it has the function of easy degradation, it is only suitable for specific application fields and certain plastic products, such as disposable packaging materials, plastic film, medical and health materials, etc. These products are seriously polluted and difficult to recycle or even collect value of use. Small, little or no benefit, so the use of degradable plastics can make waste volume reduction, so as to achieve the purpose of reducing environmental pollution.

• Some of the degradable plastics currently entering the market are disintegratively degradable, and they cannot be quickly degraded and completely degraded, but they can be degraded and disintegrated into fragments that are easily consumed by the environment under certain environmental conditions and within a certain period of time. With time, it will eventually enter the natural world. Fully biodegradable plastics can be decomposed into CO2 and water faster and more completely under certain environmental conditions. Combined with composting treatment methods, they are complementary to recycling and are considered to be good for the pollution of plastic packaging waste. The measures are the current direction of international development.

·Research and development and application of biodegradable plastics, whether from the actual perspective of global environmental protection or the gradual replacement of inexhaustible renewable resources gradually reduced, and non-renewable petrochemical resources and the strategic height from the implementation of sustainable development All have important significance.

5 Introduction to Waste Recycling Methods

5.1 Material recycling

After the packaging waste is recovered, it is classified and cleaned, dried and pelletized and then re-used as a raw material to produce plastic products. This recycling method has made progress in recent years, and its use has also been expanded. The following items have been successfully implemented.

·The Hamburg Hamburg Cleaning Agency established a 4kt/a waste plastics recycling plant in 2002. It collected waste plastics based on HDPE laundry detergent bottles from the recycling center, and used T&H's separation technology to produce highway noise insulation building materials and grain for imitative wood products. material. In addition to the 450-mark processing fee charged per ton from the recycling center, the price per metric ton of pellets is 320 DM, which is welcomed by users because the new price is 1400 DM/t.

· Austria's WKR company's regeneration unit is 6kt/a, and it collects waste plastics based on LDPE film from the recycling center and produces recycled pellets for black plastic garbage bags made in Italy. A mark processing fee of 1 mark per kilogram is charged. The actual cost is 0.9 mark, and then it is sold at 0.35 to 0.45 mark per garbage bag. The benefit is very good.

· France’s Micronil company has a technology that uses the impact value of PVC and PET for crushing and impact separation. This technology and its associated ethylene recycling company invest 40 million francs in accordance with the French preferential policies for renewable resources. Another 12kt/a No. 3 production line was built. The company's waste plastics recycling capacity reached 25kt/a. Another SIP company invested 78 million francs to build a 5kt/a production line of European-standard recycled plastic boards.

· The European Coca-Cola Company's 2L Coke cans made of recycled PET have been marketed in Switzerland. The structure is divided into three layers. The inner and outer surfaces are new materials, and the middle is recycled materials. US Wellman uses 100% recycled PET to produce hot-pressed containers for wild vegetables and fruit packaging.

· Japan's Nintendo Co., Ltd. and carpet fiber company jointly developed the technology of smashing and melting polyester fibers after PET bottles were used. Toyo Textile Co., Ltd. has begun to use them for the production of polyester staple fibers and textiles for clothing, and Mitsubishi Corporation Ltd. Outside sales of fabrics and garments, led by them, Dongle and Itochu Corporation also actively participated in the promotion.

· Japanese Willow packaging industry and Mitsui Petrochemical, Takeno Iron Works and other units jointly developed a successful use of waste PET bottles to make block stone technology. After the PET bottle was crushed and made into pellets, it was melted at 280°C and extruded into φ150mm, monolithic 500g blocks for road foundation. It is lighter than natural stone, has good drainage and has a low vocal tone. It not only replaces natural quarrying, but also cuts the waste to 1/20, and it is also a potential oil ore that can be extracted in an emergency.

(to be continued)