Plastic products are made of matrix resin and plastic additives . Many additives will be detached from plastics during processing or use due to physical or chemical effects such as volatilization and decomposition, which not only reduces the performance of plastics. Moreover, because of the toxic and harmful substances contained in the traditional auxiliaries, the environment is greatly harmed. Therefore, to achieve environmental friendliness of functional materials, it is first necessary to achieve greening and non-toxicity of plastic additives.
The construction of green plastic additives should be based on the principle of life cycle analysis (LCA) and source control, zero emission, from the source of additive structure design, production and compounding, to the use of products, to the disposal of waste, etc. Ecological design of the plastics additive product system throughout the life cycle. Accordingly, the greening of plastic additives should include the greening of the raw materials, the greening of the synthesis process, the greening of the auxiliary products, the recyclability of the additives and the environmentally dissipative four parts.
(1) Greening of plastic additives for the synthesis of raw materials.
The greening of raw materials for the synthesis of plastic additives is an important part of the source treatment. It requires the selection of additives for the synthesis of raw materials, while ensuring that the additives have the appropriate performance and price ratio, and should reduce the use of low or low boiling points. It is highly volatile, or contains toxic, harmful elements and compounds (such as lead, cadmium, halogen and other elements and formaldehyde and other compounds), and the use of high boiling point, low volatility, compatibility with the resin and non-toxic Or low-toxic raw material varieties, to ensure that the auxiliaries are released into the external environment as little as possible within the service life of the functional plastics, even if released, it will not cause great harm to the environment.
(2) Greening of the synthesis process of plastic additives.
1 Greening of synthetic technology routes. The reactants are converted into products as much as possible to maximize the utilization of the reactants, which is beneficial to cost saving, high efficiency, uniformity and stability, and non-toxic or low-toxic by-products. And can be removed from the main product by a general method; 2 greening of the solvent. In the synthesis process of traditional plastic additives, most of them need to use organic solvents, and most of the organic solvents are toxic. If they are dispersed into the air during the synthesis process, or are not treated after the synthesis, Recycling is discharged into the environment, which inevitably favors a large amount of pollution to the environment. Therefore, active synthetic solvents for plastic additives should use non-toxic, green solvents such as water, alcohol, etc., and use less organic solvents such as triphenyls that pose a threat to the environment and human health, so as to eliminate them from the source. Possible hazards from solvents. For some toxic solvents that must be used, attention should be paid to their recycling and harmless treatment. Many scientific and technological workers have made diligent efforts in the replacement of toxic and harmful organic synthetic solvents, and have also made gratifying achievements, including: the application of supercritical fluid technology, the preparation and application of ionic liquids, and the study of immobilized solvents. And application.
(3) Greening of plastic additives.
The greening of plastic additives requires that the synthesized additives are non-toxic and efficient, can maintain the stability of properties during the processing and use of functional plastics, and play a long-term role in the service life of plastics to reduce the additives. The amount of use, thereby reducing the harm caused by its production to the environment. To this end, in addition to non-toxic, high efficiency, plastic additives mainly should have the following properties: 1 good thermal stability; 2 good dispersion; 3 color pollution is small.
(4) Recyclability and environmentally dissipative properties of plastic additives.
The recyclability of plastic auxiliaries means that after a single processing of a plastic product, the additive added can be reprocessed multiple times without seriously damaging its original function. For the auxiliaries in waste plastics, if they can be recycled and reused after taking certain technical measures, it will also reduce the cost and reduce the pressure on the solid waste treatment system. Make a positive contribution.
The environmentally dissipative property of plastic additives refers to the additives in plastic products that cannot be recycled and reused. After the garbage disposal system is used together with plastics, it should have better environmental coordination and promote the disposal of discarded plastic materials. At present, the conventional garbage disposal technology adopted in China is reduced and harmlessly treated to achieve the purpose of comprehensive management. At present, there are three main methods for domestic waste disposal: landfill, composting and incineration. This requires that plastic additives can promote at least no degradation of plastics during landfilling, and do not produce harmful effects on soil and crops during composting. Decomposes substances and does not produce toxic and harmful gases when incinerated.
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