Due to the wide application of plastic products, plastic waste products and corners of various plastics are visible everywhere in our daily life environment. These waste plastic products are not easy to decompose and are not easy to rot. They exist in the natural environment for a long time, cannot disappear naturally, or float on the water surface, or are mixed in the soil, or hung on the branches, causing pollution to the environment. If it is collected and burned, it will emit a lot of harmful gases, causing air pollution. It can be seen that only the collection of waste plastic products for recycling and utilization is the best and most beneficial solution.
The recycling of waste plastic products can save a lot of raw materials for plastic molding, which can reduce the manufacturing cost of plastic products, and the waste plastics used for recycling can also have plastic products that are non-corrosive, non-corrosive, soft and light, and can be manufactured. The characteristics of forming complex products of various shapes.
The waste plastic products used in the recycling system can be used to manufacture plastic pipes, pipe fittings, plates, linings for artificial leather, floorboards, blown films and the like.
Classification and cleaning of waste plastic products
The collection of waste plastic products, a wide variety, and a wide variety. First, the film, sheet, board, and tube should be separated according to the variety of plastic products: pipe fittings, profiled materials, daily necessities, and footwear, etc., stacked separately. Then, according to the discrimination method of the common plastic products in Table 7-1, the plastic products are stacked according to the different classification of the raw materials for the products.
The waste plastic products stacked by handcuffs are cleaned to remove sediment, oil and debris → sorted according to the raw materials used by the products (refer to Table 1) → dry and dehumidify the respective stacked products after washing and pulverize (pulverize the hard products) Machine crushing, soft product film with shear mill, can also be mixed into a sheet on a two-roll mill to pelletize on the pelletizer) → add a certain proportion of auxiliary materials as needed, mix evenly → extrude Machine plasticizing granulation → bagging.
The cleaning method of the waste plastic products is as follows.
1 Wash in river water or pool. This process is mainly to remove the dirt, sand and the like adhering to the surface of the product.
2 Remove oil stains. In the pool, the waste plastic product is first washed with detergent or alkaline water, so that the oil on the product can be washed away, and then washed once in the clean water tank to remove the detergent remaining on the product.
3 For waste plastic products mixed with a small amount of iron scraps, the iron scraps can be removed by magnets; for waste plastic products mixed with cotton yarn and other debris, soaking with concentrated sulfuric acid can be used to corrode cotton yarns and then use water. Cleaning to remove sulfuric acid remaining on waste plastic products.
The waste plastic products after cleaning and drying should be carefully pressed according to the raw materials for manufacturing (refer to Table 1), the varieties of the products (tubes, tubes, plates, films, daily necessities, shoes and products, soft, hard and various colors, Shallow, etc.), and stacked and granulated separately.
Table common plastic products identification comparison
| project name | Appearance feature | Combustion characteristics | Condition in liquid |
| Polyvinyl chloride products (PVC) | The product is slightly yellowish and slightly transparent, indicating a lustrous, hard, semi-rigid and soft product. Sinking in water, density is 1.35 ~ 1.60g / cm 3 | Flame-retardant, burning in the fire source, the flame is yellow, the lower end is green, white smoke, exudes a pungent sour taste, softens and can be drawn, and self-extinguishes after the fire source | In the water, sink to the bottom, sink in a salt solution (25 ° C, density 1.19 g / cm 3 , preparation ratio of water 74mL, salt 26g), in alcohol solution 25 ° C, density 0.925g / cm 3 , water 100mL, 95% alcohol 140mL) sinks, sinks in calcium chloride solution (density 1.27g/cm 3 , industrial calcium chloride 100g, water 150mL) |
| Polyethylene products (PE) | The product is milky white, LDPE is translucent, softer than HDPE, and has a slippery feel when touched by hand, which is soft and tough. HDPE is milky white, opaque, hard and tough. Can float on the surface | Easy to burn, continue to burn after leaving the fire source, the upper part of the flame is yellow, the bottom part is blue, smokeless, can melt and drip, emitting the smell of wax burning | It can float on the water in the water. It can also float on the surface of the water in the calcium chloride solution (density 1.278/cm 3 , the same ratio as above). In the alcohol solution (the ratio is the same as above), the low density polyethylene can float on the surface. |
| Polypropylene products (PP) | The product is white waxy, translucent, harder than polyvinyl chloride products, slightly brittle, lighter than LDPE | It is easy to burn. It will continue to burn after leaving the fire source. The upper part of the flame is yellow, the bottom is blue, and there is a small amount of black smoke. It can melt and drip, and it smells like oil. | In water, alcohol, calcium chloride liquid (matching the same as above) can float in the liquid surface |
| Polystyrene products (PS) | The product is glossy white transparent wax (referring to undyed products), which is similar to glass tapping, has a crisp metal sound, is easy to break, and is brittle. Modified PS products are opaque | It is easy to burn, and continues to burn after the fire source. The flame is orange-yellow. In the smoke, there is a burning charcoal in the air, softening and foaming, and emitting aroma. | In the water, alcohol solution (formulation as above) sink to the bottom, in the salt and calcium chloride solution (same as above) can float in the liquid surface |
| aBS products | The product (undyed) is light ivory, opaque, shiny, and hard and tough | It is hard to burn, burns slowly in the fire source, can self-extinguish from the fire source, the flame is yellow, there is black smoke, there is a special smell, no melt dripping phenomenon | In the water and alcohol liquid (alcohol solution ratio as above) sink to the bottom, can float on the surface of the salt and calcium chloride solution (same as above) |
| Polyamide products (Pa) | The product is milky white, translucent | It is hard to burn, slow burning in the fire source, slowly extinguished from the fire source, the top of the flame is yellow, and the lower end is blue melted and dripped, foaming, emitting the smell of wool and nails. |
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