Polystyrene (PS) has the advantages of transparency, insulation, easy dyeing, not easy to absorb water, low production cost and wide application range. At present, China's PS recycling sources are mainly concentrated on waste electrical appliances (high impact polystyrene HIPS), daily transparent plastic products (general polystyrene GPPS) disposable lunch boxes, foam packaging filler (expanded polystyrene EPS).
PS recovery status and regeneration technology:
At present, Japan has the highest PS recovery rate of 72%, followed by South Korea and Europe, reaching 60%. Due to the imperfect recovery mechanism in China, the recovery rate is only 10% ~ 30%.
The waste of ordinary polystyrene and high impact polystyrene can be directly crushed, melted, extruded and granulated after cleaning.
The recycled material is usually a single hips resin or ABS resin, which needs to be sorted during the regeneration process, and the color of the recycled material turns yellow and the transparency decreases.
Foamed materials (EPS) are mostly building insulation layer and disposable outer packaging materials. The volume reduction (defoaming) during recycling has a great impact on transportation cost and recycling processing. Solvent method, mechanical method and heating method are used for volume reduction. Different methods have different effects on the quality of recycled materials.
The physical and chemical properties of PS were well maintained by washing, crushing, melting and extrusion, but a small amount of molecular chains were broken and the relative molecular weight was reduced after several times of heating. The impact strength and elongation will decrease
After being directly broken, the foamed waste plastics will be transported with low cost performance as filling materials for building materials.
Recovery of PS monomer, diesel oil and gasoline by thermal decomposition (chemical regeneration)
High reaction environment (high temperature and high pressure), high requirements for catalyst activity, selectivity and service life, environmental hazards of organic solvents and high water cost.
Application of PS recycled products:
Clean and transparent recycled materials without impurities can be directly added to new materials.
Miscellaneous recycled materials are usually used in non food contact products, packaging boxes, insulating parts, pallets, toys and dustbins.
Styrene waterproof and moisture-proof coating, protective paint and binder.
Waste PS foam and cement are made of lightweight building boards, columns and partitions.
Mix synthetic rubber to make sole, handle, etc.
Nowadays, the recycling rate of plastic materials has been increased in China, but the recycling rate of plastics has not been improved in the world We hope to support the development of waste plastics recycling industry by means of policies, taxes and other means. However, there are no corresponding standards to judge the naming, product quality and compliance of recycled plastics in China. In order to avoid the intermingled quality of recycled products, standardize the production and trade of recycled plastics, and promote the high-quality development of domestic recycled plastics industry, the National Technical Committee for plastics standardization has started Research and development of national standards for recycled plastics.
According to the third batch of national standard preparation and revision plan in 2019, polystyrene and impact polystyrene recycled plastics with wide sources and large volume are listed as the sixth part of the series of standards, plastic recycled plastics Part 6: polystyrene (PS) and impact polystyrene (PS-I) materials. The first drafting unit is Shanghai Yingke Industrial Co., Ltd. the standard project working time is from 2019 to 2021. It is under the jurisdiction of SAC / tc15.
One Domestic industry survey
According to statistics, China's Polystyrene output in 2019 will be 2.665 million tons, an increase of 4% compared with that in 2018 of 2.562 million tons. The main uses are various industrial product shells, insulation materials, etc. Subject to the 2018 anti-dumping investigation ruling, Chinese mainland suffered substantial damage, and many enterprises directly imported polystyrene. In 2018 and 2019, the import volume of polystyrene was more than 1.15 million tons, almost double the annual growth rate before.
From 2015 to 2019, China's total imports of recycled PS first stabilized and then increased sharply, from 729500 tons in 2015 to 1.2 million tons in 2019, with a cumulative increase of 470500 tons, an increase of 64.50%.
Domestic PS recycled materials are mainly used in the following fields:
1.EPS insulation board is the largest field of PS recycled materials, and its consumption ratio is 81.5%.
2.PS low foaming coextrusion wood like wood for construction and decoration is the second largest field of PS recycled materials, and its consumption ratio is 9.7%.
3.TPR sole industry mixes a small amount of PS recycled particles to increase the hardness of the sole. However, due to the high requirements of export orders on the quality of sole, the consumption of EPS recycled materials in the sole industry is only about 6%.
4.The advertising ktboards mainly use PS recycled materials as raw materials, while high-end ktboards such as toys are mainly mixed with PS new materials. With the current market share of advertising ktboards gradually reduced, the consumption of EPS recycled materials will also be reduced, accounting for only about 2%.
5.PS injection molding products such as electrical and electronic products, CD boxes, transparent clothes racks, stationery and other fields, the proportion of PS recycled materials is very low, the main reason is that the quality of PS recycled materials is not high, it is difficult to meet the performance requirements of products.
Before 2017, there were more than 10000 PS recycled plastics processing factories in China, mainly distribu ted in Guangdong, Jiangsu, Zhejiang, Shandong, Henan and Hebei. The industry concentration was low, and more than 95% of the enterprises' annual production capacity was below 3000 tons. The enterprises with an annual output of more than 10000 tons are mainly Shanghai Yingke industry, Shandong Yingke environmental protection, Dongguan Lianji, Foshan Huanfa, Dongguan Tongmei, Guanggang MBA, etc. After 2017, affected by the implementation of the ban on the import of recycled plastic waste, some recycled plastics processing enterprises changed to build factories abroad, Malaysia.
Two Working group established
The National Plastics Standardization Technical Committee (SAC / tc15) held the third working meeting of national standards for recycled plastics series in Chengdu, Sichuan Province from September 3 to 4, 2019. A working group was set up to form a verification test scheme for some standards of ABS, PS, PC and PA.
Sinochem Technology Co., Ltd. and Shanghai Sinochem Technology Co., Ltd. assist the quality inspection units of Sinochem and Shanghai Chengde Environmental Protection Technology Co., Ltd.
The working group mainly investigated the market information of PS recycling market, collected relevant laws, regulations and standards, and completed the standard draft and verification test scheme of this document during this period, contacted several domestic PS recycling production and utilization units, such as Ningbo dopoda, greenway, Anhui Huachen Plastics Co., Ltd. to provide samples, and actively participated in the formulation of PS regeneration particle standard
