| When plastic is exposed to heat or light,the plastic polymer is more likely to be oxidized,thereby accelerating the aging rate.Hindered phenols light stabilizer is a class of compounds,which is used for plastic to reduce or restrain the light aging rate of the plastic material,and improve the light resistance of the plastic.As an important polymer material,plastics are widely used in daily life because their good use characteristics.Plastic also have aging phenomenon,because plastic polymers is susceptibly oxidized under the heat or light,thereby exacerbating the rate of aging.Plastic light stabilizer is a kind of substances that can reduce or restrain the light aging rate and improve the light resistance of plastic by shielding or absorbing ultraviolet energy.According to the mechanism,plastic light stabilizer can be divided into light shielding agent,ultraviolet absorber(UV absorber),quenchert and free radical catching agent.Hexadecyl 3,5-di-tert-butyl-4-hydroxybenzoate(UV-2908)and 2,4-di-tert-butylphenyl 3,5-di-tert-butyl-4-hydroxybenzoate(UV-120)are two hindered phenolic light stabilizers with antioxidant activity and ultraviolet absorption properties.Among them,UV-2908 is used in polyolefin plastics such as PP and PE,especially colored opaque products,because it has the characteristics of good compatibility,small coloring property,low volatility,good chemical stability,acid and alkali resistance and low toxicity.UV-2908 can also be used together with antioxidants(including phenols and phosphites),ultraviolet absorbers(benzophenones)and other light stabilizers(hunted amines)to effectively decompose hydroperoxides produced in plastic polymers to improve outdoor weather ability.UV-120,used for plastic,rubber and other industries,which is apply to polyethylene,polypropylene,polystyrene,polyoxymethylene and other plastic products,especially suited for polypropylene film,narrow band and fiber,it has minimal coloring property,low volatility,high thermal stability and resistance to extraction of washing solution.UV-120 has better antioxidant effect,when it works synergistically with benzotriazole ultraviolet absorbers and nickel chelate light stabilizers.3,5-di-tert-butyl-4-hydroxybenzoic acid(UV-612)is the main raw materials of UV-2908 and UV-120,which are reacted with hexadecanol or 2,4-di-tert-butylphenol to obtain the target products.Catalyst is the main factors influencing the results.The synthesis of UV-612 is also a key step in the preparation of UV-2908 and UV-120.The main synthetic methods of UV-612 including direct oxidation method,bromination hydrolysis oxidation method and Kolbe-Schmidt method.Among them,Kolbe-Schmidt method is mainly used in industry,which is obtained UV-612 start with 2,6-di-tert-butylphenol.First,2,6-di-tert-butylphenol forms salt with alkali,then reacts with carbon dioxide at high temperature and high pressure.At present,it isn’t the best quality that the commercially available UV-612 and UV-2908.There are a lot of “three wastes” are generated and cause environmental pollution during the production process of UV-612,UV-2908 and UV-120.Therefore,this study has made special research to solve above problems,for improve the product quality and reduce the discharge of “three wastes”.The research of this topic includes three parts:1.Use the Kolbe-Schmidt method to prepare UV-612 and study the reaction results of the single solvent method and the mixed solvent method,and explore the influence of temperature,pressure and other conditions on the reaction results;To improve product quality,analyze the impurities in the system and the research on the impurity removal process;Carry out the research on ton-level pilot test technology and promote the progress of green industrialization of UV-612.Through this study,the product was purified by using multiple step-by-step extraction technology and high-efficiency crystallization technology,improve the quality of the product;N,N-dimethylformamide alkaline solvent was used as the reaction medium for Kolbe-Schmitt,which reaction improves the conversion efficiency,reduces the solvent consumption,and reduces the production cost;The 2,6-di-tert-butylphenol will recycle the unreacted raw material,and the solvent recovery is applied mechanically.The safety performance of the device is reliable,and the production process can greatly reduce environmental pollution.2.Use the esterification method to prepare UV-2908,and study the influence of acidic ionic liquid as a catalyst on the reaction;Analyze the impurities in the system and the research on the impurity removal process to improve product quality;Conduct the research on the ton-scale pilot test process to promote the progress of green industrialization of UV-2908.The use of a new type of ionic liquid catalysis can effectively avoid the use of some toxic and corrosive catalysts,with high catalytic efficiency and environmental friendliness;Impurities are removed by recrystallization,which improves the output and quality of UV-2908.3.Use UV-612 as raw material,and continue to study the application of synthesis of acidic ionic liquid catalysts in light stabilizer for UV-120;Do the analysis of impurities in the system and the research on the impurity removal process to improve product quality;Carry out the research on the ton-level pilot test process to promote the progress of UV-120 green industrialization.This study extends the application of ionic liquids in the synthesis of hindered phenolic light stabilizers. |
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