Waste plastic

- Aug 16, 2019-

Waste plastic is a popular term that does not refer to waste, old or useless plastic products. The vast majority of plastic products, especially a large number of disposable use, after the use of the plastic material itself performance has not changed greatly, so it is completely possible to recycle with appropriate methods after re-processing into plastic products for re-use.

Basic introduction

Waste plastic is a popular term that does not refer to waste, old or useless plastic products. The vast majority of plastic products, especially a large number of disposable use, after the use of the plastic material itself performance has not changed greatly, so it is completely possible to recycle with appropriate methods after re-processing into plastic products for re-use.

Waste plastic is more formally called the consumption of plastic waste, refers to the consumption or use of waste plastic products. Plastic in the synthesis, processing, circulation also can produce waste, waste, the plastic waste, also called plastic waste before consumption, although it is within the scope of waste plastic, but because of its volume is relatively small, easy to recycle and recovery value is big, the general manufacturers will be their recovery and recycling products directly used in production. Therefore, we usually said that the waste plastic mainly refers to the consumption of plastic waste. Without specific explanation, the reference [1] mentioned by the recycling business network also refers to plastic waste after consumption.

produce

In our daily life and agricultural production in various fields, plastic products everywhere, when the life of these products or use purpose, will be discarded and become waste plastic. Of course, the sources of waste plastics are not limited to this, as mentioned in front of the recycling business network, every link of plastic synthesis, molding, circulation and consumption will produce waste or waste products. Its specific source mainly has the following aspects.

Produced in resin production

Waste materials generated in resin production can be mined in the following three aspects:

1. During the polymerization process, scrape off the paste auxiliary materials (commonly known as "pot") from the inner wall of the reaction kettle and unqualified reaction materials.

(2). Mixing process of extruder cleaning waste and unqualified mixing.

(3). Transportation, storage process of landing materials (throwing materials) and slag.

The amount of waste depends on the complexity of the polymerization reaction, the number of manufacturing processes, production equipment and operational proficiency. In all kinds of resin production, polyethylene produced the least waste, polyvinyl chloride produced the most waste.

Formed during processing

In the various molding processes of thermoplastic plastics, there will be different amounts of waste products, foreign products and scraps. Such as injection molding in the six cold material, cold solid sprue material, cleaning machine waste, waste side, etc. The scrap of cleaning machine, trimming material and cutting material on the final product in extrusion molding; Wear blank mouth of blow molding machine in the process of blow molding, cold solid material and cleaning waste material in the equipment, as well as the flash edge of hollow container, etc. (the waste rate of wearing butt mouth when producing with handle bottle can reach %40); Waste products, trimming materials and waste products dropped from mixer and calender during calender processing; Rolling plastic processing in the mold on the overflow, take out the edge seam materials and waste products.

The amount of waste produced in forming process depends on the processing technology, mold and equipment, etc. Generally speaking, this kind of waste material has high recycling efficiency. They are clear in variety, clear in packing, and have little pollution. Their performance is close to that of the original material, and the pretreatment work is small. Usually, they are only used for crushing treatment, which can be used as the turning back material to be mixed into the new material, and have little influence on the performance and quality of the products.

Thermosetting plastics in the molding process will also produce waste, waste, such as waste products have occurred crosslinking reaction, the recycling of these waste products is very difficult.

Produced during mixing regeneration process

The waste products produced in the mixing and recycling process only account for a small part of all waste plastics, which are the waste products removed in the mixing equipment cleaning machine and the defective products under abnormal operation conditions, most of which are recyclable waste plastics.

Produced in secondary processing

Secondary processing is usually will buy from molding processing plant to plastic semi-finished products after transfer printing (meaning: will be raised on the formation of the toner image transfer to paper the process of transfer printing), sealing, thermal forming, mechanical processing, such as processing into finished products, waste from here tend to be more difficult than forming a waste from factories, such as processed waste by printing, electroplating, etc, to remove the printing layer, electric plating are of great difficulty and cost, and directly crush or granulation is recycled material, its value is much lower. It is easier to recycle the waste edges and particles generated by thermal forming and mechanical cutting, and the value of recycling waste materials is also relatively high.

Post-consumption generation

This kind of waste plastics come from a wide range of sources and are used in a complicated way. Such wastes include:

(1) bags and drums used in the chemical industry.

(2) containers, artificial fibers, etc., in the textile industry.

(3) packaging materials and foam shock-proof pads in the household appliance industry.

(4) building materials and pipes in the construction industry.

(5) shrinkage film and stretch film in canning industry.

(6) turnover boxes and egg trays in food processing.

(7) in agriculture, mulching film, greenhouse film, fertilizer bag, etc.

(8) nets, floats, etc., in fisheries.

(9) bumpers, fuel tanks, battery boxes, etc. removed from scrapped vehicles.

Municipal solid waste

This kind of waste plastics also belongs to post-consumption plastics. Due to its large amount and difficult recycling and utilization, it has posed a serious threat to the environment and is the focus of future recycling work, so it is classified separately. In China's urban household waste, waste plastic accounts for %2~%4, most of which are disposable packaging materials, they are basically polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), polyethylene terephthalate (PET) and so on. In these waste plastics, polyolefin (PO) accounts for 70 %.

There are many kinds of waste plastic products in household garbage, including all kinds of packaging products, such as bottles, films and cans. Daily products, such as barrels, basins, cups, plates, etc. Toys accessories, entertainment supplies, clothing and footwear, strapping rope, packing tape, woven bags, health care supplies, etc.

identify

And recycled plastics

Waste plastic is directly crushed into powder or granular plastic products, which can still be distinguished, such as injection molding, wire drawing, film and so on. And recycled materials are recycled do not know how many times can not accurately distinguish what things, can only be classified according to the number of cycles, the minimum start, super grade, level one, level two such points.