Abstract : The principle of recovery and utilization of recycled plastic packaging used as raw material, technology and related issues were studied.
Keywords: packaging; recycling; utilization; raw materials
Raw material recycling refers to recycling of plastic packaging materials. Materials using this raw material recycling technology and process only change the shape and structure of the recycled plastic package without changing its physical and chemical properties. For the raw material type recycling of plastic packaging, the final technology and process treatment result in a plastic raw material (recycled plastic particles) that can be reused to manufacture the same or similar packaging products.
1 Technical principles
The principle of plastic packaging material recycling technology refers to the waste plastic after the pre-processing crushing directly plasticized, and then molding or granulation, in some cases the need to add a certain amount of new resin, made of recycled plastic products process. It can use existing technology, equipment, both economic and efficient. In this process, appropriate additives (such as antioxidants, lubricants, stabilizers, plasticizers, colorants, etc.) must be added to improve the appearance and aging resistance and improve the processing performance, but the mechanical strength of the material and No effect on performance (does not increase but decreases intensity as much as possible).
The technology can be divided into three methods depending on the source and purpose of waste plastics.
(1) It is not necessary to carry out preliminary processing such as sorting and cleaning, and crushing directly after plasticization. This method is mainly used for scrap and defective products in the production of packaging products. They can be sent directly to the hopper and used with new materials without any pre-treatment. This method can also be used for the recycling of some plastic containers and products that have been used but are very clean and free of any pollution.
(2) Recycling such as sorting, washing, drying, crushing, etc. is required. This is mainly required for those plastic packaging materials and products containing a lot of pollution components and impurities. Firstly, rough washing is performed on the recycled materials to remove impurities such as sand, stones, and metal to prevent damage to the machine. After rough washing, the material is dewatered centrifugally and then sent to the crusher for crushing. After crushing, fine crushing is performed to remove the inside of the package. Impurities. After cleaning and then drying, plasticization or granulation can be performed directly. The object of this method is generally plastic packaging waste collected from different channels after commodity circulation, various uses and various shapes of packaging containers, packaging bags, film sheets and so on. It is characterized by a lot of impurities, and it is difficult to deal with serious contamination. In order to obtain better results and the best economic benefits, this method requires the classification of raw materials for waste.
(3) Special pretreatments must be carried out before recycling. For example, PS foam packaging products, which are inconvenient for transportation and storage, are not easy to input into the processing machinery in the process. Therefore, a preliminary deaeration and volume reduction treatment is required. Specific treatment may be used for special foam removal or extrusion equipment ( Such as compactors, etc.). For different recycled plastic packaging materials, after the above-mentioned three different pretreatments are performed according to the requirements, plasticization, homogenization and granulation can be performed (some tubes can be directly formed and other shaped products can be obtained). Table 1 shows the application of recycled plastics.
(to be continued)