The hottest physical recycling process of pet

Pet physical recycling process

development prospect of plastic recycling

with the development of economy and the improvement of people's living standards, various plastic products not only bring convenience to people's lives, but also bring terrible "white pollution" to people. Therefore, the study of the final treatment of waste plastics has become more and more valued by governments all over the world, The recycling and utilization of waste plastics are directly related to environmental protection, air pollution, and even the survival of the plastic industry. This technology has been widely used in the development of production lines such as chemical fiber, film, profile, pipe, plate, cable, composite extrusion, granulation, etc

according to the statistics of China Plastics Processing Industry Association, the output of plastic products in China was 4479 tons in 2009, and the consumption of plastic products has exceeded 60million tons, accounting for one quarter of the world. The per capita consumption is 46kg, exceeding the international average of 40kg. According to relevant statistics, the utilization market of waste plastics in China is worth more than 100billion yuan. Therefore, it is of far-reaching significance to study the recycling and utilization of waste plastics in China, both for environmental protection and sustainable economic development

the development prospect of PET recycling

Pet plastics are widely used in the field of packaging, whether it is packaging film, coiled material, or container bottles. With China's entry into WTO and 30 years of reform and opening up, China has gradually occupied an important position in the field of world commodity processing and production, and has increasingly become a major commodity production country. With commodity production, commodity packaging enterprises have also developed rapidly. PET material plays an important role in commodity packaging materials. With the further development of China's economy, the demand for PET packaging materials will further increase. It can be seen that the development of PET bottle recycling in China has both great necessity and broad prospects

pet physical recovery process

pet physical recovery method is a method of granulating waste PET bottles after separation, crushing, washing and drying

at present, most pet bottle caps are made of PP and HDPE, which should be removed before crushing the bottle. If it is mixed into pet, the physical and mechanical properties of pet recycled materials will be significantly reduced due to the poor compatibility between PE, PP and pet

at present, the most economical way to remove PVC labels on PET bottles is mainly to rely on manual sorting. Before crushing the PET bottle, the label is relatively intact, which is easy to remove and separate; Once broken, it is difficult to remove the label, so the removal of the label should be arranged before breaking the bottle; The labels sorted out can also be collected and applied

there is also an advanced pet bottle separation system, and the investment will be larger. The PVC sorter for PET bottles developed with the most advanced international infrared image recognition technology can automatically identify the mixed PVC sheets or sealing films in the bottles, with a rejection rate of 90% and a maximum PVC content accuracy of 5ppm

in principle, the ordinary rotary knife plastic crusher can be used for the crushing of waste PET bottles. However, due to the thin wall thickness of PET bottles, the spacing between the fixed knife and the moving knife should be as small as possible. At the same time, considering that PET bottles have great hardness and toughness, and the recycled waste PET bottles are inevitably mixed with impurities, which will aggravate the wear of knives, so the moving knife and the fixed knife are best made of cemented carbide steel with better wear resistance

during the crushing process, the overall size of the material particles should not be too large, otherwise it is easy to "bridge" at the blanking place and affect the plasticization. Generally, it is recommended that the particle size be less than 10mm

due to the strong water absorption of pet, special attention must be paid to moisture resistance during storage, and effective dehumidification and drying must be carried out before processing. The drying conditions are usually 160~180 ℃ for 4~6 hours. In order to prevent the plastic particles from hygroscopic again, when they are transported to the molding machine for a long distance, they must be kept warm at a temperature above 140 ℃. In order to prevent the plastic from turning yellow during shutdown, the dehumidification and drying machine needs to be cooled to 100 ℃ and only kept warm without dehumidification

before the injection molding of the bottle blank is completed, the PET particles must be dried until the moisture content is below 0.005% (50ppm), so as to produce a good amorphous transparent bottle blank. Generally, the proportion of recycled materials should not exceed 25%, and the recycled materials should also be thoroughly dried

pet crystallization time is 1~2 hours, and the crystallization time is inversely proportional to the pre crystallization temperature. Generally, the higher the drying wind speed is, the higher the operating speed of pet and air flow is compared with that of the experimental machine that people can control after arranging a table, so the drying time will be shortened, but the dust generated by the system will also increase correspondingly, so we must consider removing too much dust. Generally, the wind speed used for hopper drying is 8~10m/s

when used in bottle blank or injection molding, the reference value of unit drying air volume required by pet is 1.7~2.5nm3/hr-kg. When used in extrusion molding, the reference value of unit drying air volume required by pet is 1.2nm3/hr-kg. Of course, the values proposed by the raw material suppliers are not consistent, and the specific values provided by them should be used as a reference

the large dehumidification and drying system manufactured by Xinyi Group can be up to 1000kg/hr when used to treat PET raw materials. The system mainly includes a honeycomb rotary dehumidifier with a drying air volume of up to 4000m3 per hour and an insulated drying bucket with a material capacity of up to 8000L (the effective weight when loading pet is 6400kg). The final moisture content of the dried raw materials processed by the rotary dehumidifier can be up to 0.004%. (end)