Overview Recycled plastic is the reuse of plastic. After the mechanical blade crushing operation, the reuse of plastic is completed. Recycled plastics refer to plastic raw materials obtained after processing waste plastics through physical or chemical methods such as pretreatment, melt granulation, modification, etc., and are the reuse of plastics.
Plastics have good processing properties and are easy to form, such as: blowing, squeezing, pressing, cutting, and welding. In production and life, many plastics can be granulated, such as waste food bags, sandals, wires, wire boards, agricultural films, tubes, barrels, basins, packing belts, and various waste plastic products can be molded and processed into plastics. The raw materials are used to make machine parts and components through special processes and formulas; they can be used to make water pipes, agricultural machinery, packaging bags, and cement bags; they can replace some wood products; they can be used to make various plastic bags, barrels, basins, and toys. And other plastic products, living utensils.
Recycled plastics and granulated plastics have broad prospects, turning waste into treasures, products (plastic pellets) are very popular, and plastic companies have a large demand. A medium-sized agricultural film factory needs more than 1,000 tons of polyethylene particles per year, and a medium-sized shoe factory It needs more than 2,000 tons of PVC particles. Smaller private enterprises need more than 500 tons of particles per year. Therefore, there is a large gap in plastic particles that cannot meet the needs of plastic manufacturers. Therefore, the market is very good and the benefits are extremely high. good. There are many sources of waste plastic raw materials. Where there are people, there are waste plastics, which are easy to purchase and cheap (as in all regions). A city consumes more than 10 tons of various plastic products such as plastic food bags every day. There are also a large number of waste plastics in rural areas that can be recycled. The pellets have no worries about sales.
World resources are always a hot topic for mankind. The slogan of saving resources has slowly penetrated into people's hearts. Therefore, the awakening of recycled materials is also inevitable, so that people can truly achieve environmental protection and energy conservation through the recycling of resources. The biggest advantage of recycled materials is that the price is definitely cheaper than new materials. Although its overall performance and attributes are not as strong as new materials, we do not need to use materials that have good properties and performance in many products. To make it, a lot of unnecessary attributes are wasted, and the recycled material is different. According to different needs, only a certain aspect of the attribute needs to be processed to produce the corresponding product, so as not to lose resource.
1) When recycling waste plastics, it is very difficult to separate and economically uneconomical.
2) Plastics are easy to burn and produce toxic gas when burned. For example, when polystyrene is burned, toluene is produced. A small amount of this substance can cause blindness, vomiting and other symptoms when inhaled. The burning of PVC can also produce toxic gas of hydrogen chloride. In addition to burning, the high temperature environment will cause the plastic to decompose toxic components, such as benzene. .
3) Plastics are made from products refined from petroleum, and petroleum resources are limited.
4) The plastic will not rot if buried under the ground for hundreds, thousands or even tens of thousands of years.
5) Plastics have poor heat resistance and are easy to age.
Due to the inability of plastics to degrade naturally, it has become the number one enemy of mankind and has caused tragedies for many animals. For example, the monkeys, pelicans, dolphins and other animals in the zoo would mistakenly swallow the No. 1 plastic bottle thrown away by tourists, and finally died painfully due to indigestion; when I looked at the beautiful and pure sea, I walked closer, and it was actually full of them. All kinds of plastic garbage that could not be contained in the ocean, in the intestines of many dead seabird samples, all kinds of indigestible plastic were found.
4. Performance changes
PVC: Discoloration is more obvious after regeneration. It will be light brown after one re-extrusion, and it will almost become opaque brown after three times. The specific viscosity will not change at the second time, and it will tend to decrease after two times. Regardless of whether it is hard or soft PVC, stabilizers should be added during regeneration. In order to make the re-products shiny, 1%-3% of blending ABS can be added during regeneration.
PE: After PE is regenerated, the performance will decrease and the color will turn yellow. After multiple extrusions, the viscosity of high-density polyethylene will decrease, and the viscosity of low-density polyethylene will increase.
PP: When regenerating once, the color is almost unchanged and the melt index rises, and the color is aggravated more than twice, but the melt index still rises. After regeneration, the breaking strength and elongation have decreased, but there is no problem in use.
PS: The color turns yellow after regeneration, so regenerated PS generally performs color difference. The degradation of the properties of recycled materials is proportional to the number of regenerations. The breaking strength does not change significantly when the blending amount is less than 60%, and the limiting viscosity does not change significantly when the blending amount is less than 40%.
ABS: The discoloration is more obvious after regeneration, but there is no obvious change in performance when the mixing amount does not exceed 20-30%.
Nylon regeneration also has problems of discoloration and performance degradation, and the blending amount should be less than 20%. Regeneration elongation decreases, but elasticity tends to increase.
5. Distinguish good from bad
1) Look at the color:
The lighter the color (even colorless and transparent), the wider the utilization range and the higher the grade. For example, white, it can be adjusted to many other colors, or it can be made back to white products, and the price is also high. Secondly, because of the needs of the product, various ingredients have been added to the raw materials.
2) Look at the content of CaC03 (stone powder)
The more CaC03 content and the lower the grade, the lower the price. From the naked eye, the product is not bright, and if it is matt (except for matt), the content of CaC03 will be high, and it will feel heavy in the hand. If it is burned with fire, the burned part will turn red and turn into ash. In addition, pay attention to reinforced (referring to glass fiber) products. The only available reinforced products are PA, PBT, PP, etc., and the prices are not high. There are also several kinds of alloy materials. At present, there is only ABS+PC in the domestic market. Others are not available. Then according to the specific gravity (density) of the raw materials to judge whether the intermixed materials can be reused. At present, the most problematic is the intermixing of ABS and PS, the intermixing of PC and PMMA, the intermixing of PVC flakes (bottle materials) and PEl, and the intermixing of flakes. PE and PP are mixed in half. After these materials are mixed, they are difficult to use because of the similar density.
3) Look at the purity of recycled plastics
The purer the material properties, the higher the grade; the impure material properties, the lower the grade, and some intermixing materials are even unclaimed.
4) The difference with waste plastic
Waste plastic is directly crushed into powder or granular plastic products, and it is still possible to distinguish what kind of material, such as injection molding, drawing, or film, etc. Recycled materials are recycled and used. I don’t know how many times I can’t tell what exactly. They can only be classified according to the number of cycles. The least start is special grade, first grade, and second grade.
6. Four points of reference for market price evaluation of recycled plastics
Evaluation of the price of recycled plastics 1. Color and performance of recycled plastics Generally speaking, the lighter the color of recycled plastics, the better the price. The closer the performance is to the new material, the better the price. The better the focused performance index, the better. 2. Purity of recycled plastics The higher the purity of recycled plastics, the better, except for modified materials, because modified materials mainly depend on performance indicators; the compatibility of components in recycled materials can also be included in this point, the better the compatibility The higher the price. 3. The appearance of recycled plastics firstly depends on the shape of the pellets. The better the pellets, the higher the price; the second is whether it is foamed, layered, whether the hardness meets the requirements, whether the color is uniform, whether the gloss is good, etc. . 4. Application of recycled plastics The use, processing characteristics, wide range of applications, and other special requirements of recycled plastics will affect the valuation of recycled plastics.
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