How to recycle polypropylene efficiently

Mitsubishi Electric Co., Ltd. has independently developed hybrid plastics picking and recovery technology to achieve "horizontal self-recycling" of home appliances (reuse from home appliances to home appliances).

In the past, after the plastic parts in the household electrical appliances were crushed, most of them were obtained as "hybrid plastics", and the re-use was very laborious. The company developed this technology to automatically pick and recycle high-purity polypropylene in "mixed plastics." Recycled polypropylene can also be used in the production of home appliances. In the future, the company will also develop technologies that can 100% recycle and reuse the plastic of home appliances.

1, the development of the background

Based on the average value of four kinds of household electrical appliances in Japan's recycling factories nationwide, the company's 2003 home appliance recycling and re-commercialization ratio reached 73.3%. Among the various resources, the recycling of metal and glass has made progress. The recycling of plastics has become the subject of today.

In 1999, the company established the first home appliance recycling and recycling plant in the same industry in Ichikawa City, Chiba Prefecture. Since then, the recycling of plastics has begun. It is also the only company in the industry that has introduced micro-crushing technology, and has achieved a downgrade of “hybrid plastics” to various miscellaneous commodities. However, the degraded use of plastics is limited to mechanical and electrical products. At that time, higher purity materials could not be used in home appliances.

Newly-developed technology can automatically select polypropylene that is used in a large amount in "mixed plastics" and recycle it in high purity. The reprocessed product can be used in home appliances and high-purity materials to realize polypropylene plastics. use.

The company also plans to develop automatic selection technologies for plastics such as polystyrene and ABS.

2, plastic recycling technology

In order to efficiently recover the polypropylene from the mixed plastic, the entire process consists of three parts: a micro-crushing process, an accurate selection process, and a synthesis process. The microcrushing process is a pretreatment of the height selection process and breaks the plastic into pieces with an average size of 8mm. In the precise selection process, polypropylene is recovered with high purity by dry and wet picking and a unique foreign material removal device. In the synthesis step, in order to ensure the quality of the recovered polypropylene, a modifier is added to make the pellets.

The process of high-efficiency recycling of polypropylene is as follows:

Raw materials → micro-crushing process → height selection process → synthesis process → plastic granules

The detailed engineering process is as follows:

(1) Micro-crushing process: As a pretreatment for the precise selection process, the machine is selected by a high magnetic force to remove the metal. The 10 to 80 mm mixed plastic was broken into pieces averaging about 8 mm.

(2) Precise selection process: Among them, there is a principle that the light objects float upward according to wind force; there is also a dry specific gravity selection that uses foreign matter to remove foreign matter, and then wet sorting using water, which is selected and selected by centrifugal force The best match is to recycle more than 99.8% of high-purity polypropylene. The company's unique device was then used to remove foreign matter that had a similar proportion to plastic, achieving higher purity recovery.

(3) Synthesizing step: A modifier is added to the selected high-purity polypropylene, and the plastic pellets are formed through extrusion processing. Thanks to the addition of the optimal modifier, plastic pellets with high purity can be reused as materials for home appliances.

3. Development plan

In mid-2005, the company will establish a new factory in Ichikawa City, Chiba Prefecture, and plans to collect 1,000 tons of polypropylene from the mixed plastic each year. It is planned that by 2008, the automatic selection technology of polystyrene and ABS will be introduced, which will increase the recycling capacity of the factory to 4,000 tons of plastic (including polypropylene) per year. (Kong Xinbo/translation)