Production method of polyethylene wax
目前，凯发k8官方网站的生產方法主要有三類：一是由乙烯單體通過低聚反應， 如通過自由基低聚方法合成的凯发k8官方网站； 二是由高聚物的降解制備的凯发k8官方网站；三是在聚乙烯的合成過程中的副產，如高壓法聚乙烯合成中的副產物經過分離得到的凯发k8官方网站。
At present, there are three main production methods of polyethylene wax: one is the oligomerization of ethylene monomers, such as polyethylene wax synthesized by free radical oligomerization; the other is the degradation of polymers; the third is the by-product in the synthesis of polyethylene, such as the by-product in the synthesis of high-pressure polyethylene. Separated polyethylene wax.
1. Ethylene polymerization
乙烯聚合法生產凯发k8官方网站主要有3 種方法，一是用自由基催化劑在高溫高壓下聚合； 二是用齊格勒催化劑在低壓下聚合；三是茂金屬催化劑聚合。
There are three main methods to produce polyethylene wax by ethylene polymerization, one is polymerization under high temperature and pressure with free radical catalyst, the other is polymerization under low pressure with Ziegler catalyst, and the third is polymerization with metallocene catalyst.
2. Polyethylene pyrolysis method
聚合法生成的凯发k8官方网站分子量分布窄， 相對分子質量大小可以人為控制，但必須在大裝置上進行，資金投入大。國內廠家一般采用高分子量聚乙烯的熱裂解法生產， 這種方法采用的原料可以是聚乙烯樹脂，也可以是聚乙烯廢塑料，前者制得的產品等級高，后者制得的產品等級低。高分子量聚乙烯在隔絕空氣的條件下可以熱裂解為低分子量的凯发k8官方网站， 這樣制備的凯发k8官方网站與結構有關的性質（如結晶度、密度、硬度和熔點）都受到裂解原料的影響。裂解加工方法分為裂解釜法和擠出法。裂解釜法是間歇式加工方法，適合于生產量較低，產能較小的廠家；擠出法是連續化生產，適合于生產量大，產能高的企業。
Polyethylene wax produced by polymerization has narrow molecular weight distribution and its relative molecular weight can be controlled artificially, but it must be carried out in a large unit with large investment. Domestic manufacturers generally use high molecular weight polyethylene pyrolysis production, this method can be used as raw materials can be polyethylene resin, can also be polyethylene waste plastic, the former product grade is high, the latter product grade is low. High molecular weight polyethylene (HMWPE) can be pyrolyzed into low molecular weight polyethylene wax (LMWPE wax) in an air-insulated environment. The structure-related properties (such as crystallinity, density, hardness and melting point) of the prepared polyethylene wax are affected by the pyrolysis feedstock. Cracking process is divided into cracking kettle method and extrusion process. Pyrolysis kettle process is a batch process, suitable for low production, small capacity manufacturers; Extrusion process is continuous production, suitable for large production, high capacity enterprises.
3. Polyethylene byproduct purification
從乙烯聚合生產聚乙烯的反應中， 副產得到的低分子量組分和溶劑的混合物中可以回收凯发k8官方网站產品。從聚乙烯裝置的副產中脫出溶劑和引發劑后，產物分子量分布仍然很寬，限制了其應用領域，需要采用溶劑分離的方式進行進一步提純。這種副產的凯发k8官方网站產品中通常含有相對分子質量在1000 左右的分子，所以在機械強度、耐熱性能等物理性能上低于乙烯聚合法生產的凯发k8官方网站產品。
Polyethylene wax can be recovered from the mixture of low molecular weight components and solvents obtained by-product in the process of ethylene polymerization to produce polyethylene. After the solvent and initiator are removed from the by-product of polyethylene plant, the molecular weight distribution of the product is still very wide, which limits its application field. Solvent separation is needed for further purification. This by-product of polyethylene wax usually contains molecules with a relative molecular weight of about 1000, so its mechanical strength, heat resistance and other physical properties are lower than those of polyethylene wax produced by ethylene polymerization.