Plastic products are widely used due to their light weight, waterproof, durable, beautiful products and mature production technology. They have become the world's top ten producers of plastic products and the largest consumer of plastic materials. . While plastic technology brings huge material civilization, the emergence of a large number of plastic waste presents severe challenges to people, but it also gives us new opportunities. The pollution caused by plastic waste is commonly known as “white pollution”. It is attracting people's great attention. Indifferent to its existence or improper treatment will cause some serious risks, such as: (1) plastic waste in the environment is not easy to rot , stacking causes more garbage dumps and increased pollution points; (2) plastic film, such as agricultural film, enters the soil, is not easy to decompose and prevent soil permeability, which makes soil quality deteriorate, affecting crop growth; (3) plastic waste accounts for 60% of marine floating matter Above, endangering marine life and maritime safety.
Therefore, the recycling and utilization of plastic waste has reached a point where it cannot be ignored. At present, the recycling technology for plastic waste can be divided into five aspects.
1 Direct recycling and modification of waste plastics Such utilization is the most important method for the utilization of waste plastics. Its technology investment and cost are relatively low, and it has become the main method for the utilization of renewable resources in many countries. Mature craftsmanship. Compared with modified recycling, the technology investment and cost of direct recycling are relatively lower, and the selection is more common, but the modified recycling is the development direction.
1.1 Direct recycling This is the process of sorting, cleaning, crushing and granulating the recovered waste plastic products directly, and also including adding appropriate auxiliary components (such as stabilizers, anti-aging agent colorants, etc.). In combination, the addition of these additives only serves to improve processability, appearance or anti-aging, and does not improve the basic properties of the recycled product. Japan's construction company pulverized waste foam and heated it by infrared radiation. Its volume was reduced to less than 20%, and then mixed with special cement to make "rice sugar"-like building materials. As a low-cost soundproof material, it has a good The sound insulation effect is very versatile.
1.2 Modification and Recycling This is a technique of modifying the recycled material by mechanical blending or chemical grafting, such as toughening, strengthening, combination, composite, activated particle filling, blending, and crosslinking, grafting, and chlorine. Chemical modification. The properties of the modified recycled product, especially the mechanical properties, can be significantly improved or improved, and can be used as a high-grade recycled product. However, the routing is complex and sometimes requires specific machinery. Almost all thermoplastic waste plastics can be collected, sorted, cleaned, pulverized and dried, and then melted. Various plastic molding processing equipment is used to produce recycled plastic sheets, pipes, rods, parts and containers. For example, disposable expanded polystyrene (EPS) foam tableware that has been banned in the country can also be modified for recycling, which can solve the problem of the tableware being banned.