Introduction of Production Method of Oxidized Polyethylene Wax
Oxidized polyethylene wax is an intermediate polymer of ethylene
oxidized polyethylene waxIt is an intermediate polymer of ethylene, neither the hard block of polyethylene nor the gaseous state of ethylene, but waxy. Hepai Chemical pointed out that its wide range of applications, in a number of industries have quite successful application cases.
The main characteristics of oxidized polyethylene wax: good hardness, high softening point, low viscosity, non-toxic, good thermal stability, low volatility at high temperature, strong internal lubricity, good external lubricity for pigment dispersion, which can improve the production efficiency of plastic processing, good moisture resistance at room temperature, strong chemical resistance, excellent electrical properties, and can improve the appearance of the finished product.
At present, there are three main methods for the production of oxidized polyethylene wax: one is polyethylene wax synthesized by ethylene monomer oligomerization, such as free radical oligomerization; the other is polyethylene wax prepared by polymer degradation; products obtained by separation of by-products in high-pressure polyethylene synthesis, such as polyethylene wax.
1. Ethylene polymerization. High temperature and high pressure free radical catalyst polymerization; Ziegler catalyst polymerization at low pressure; metal catalyst polymerization.
2, polyethylene cracking method. The molecular weight distribution of oxidized polyethylene wax produced by polymerization method is narrow, and the relative molecular weight can be controlled by man, but it must be carried out on large equipment and the capital investment is large. Domestic manufacturers generally use the thermal cracking method of high molecular weight polyethylene, which can be used as a raw material for polyethylene resin or polyethylene waste plastics. The former produces high-grade products, while the latter produces low-grade products. High molecular weight polyethylene can be pyrolyzed to low molecular weight polyethylene wax under air isolation conditions, and the structural correlation of the polyethylene wax prepared by this method can be affected by the cracking of the feedstock. The cracking processing method is divided into the cracking kettle method and the extrusion method: the cracking kettle method is a batch processing method, which is suitable for manufacturers with small production capacity and low output. Extrusion is a continuous production method, which is suitable for enterprises with high production capacity and large output. The polyethylene wax may be prepared by recycling polyethylene pyrolysis liquid. The technology is simple, the raw materials are abundant and cheap, and the operating cost is low.
3. Purification of by-products. The polyethylene wax product can be recovered from a mixture of low molecular weight components and solvent obtained as a by-product during the polymerization of ethylene to produce polyethylene. After removing the solvent and initiator from the by-products of the polyethylene plant, the molecular weight distribution of the product is still very wide, which limits its application field and needs to be further purified by solvent separation. This by-product polyethylene wax usually contains molecules with a relative molecular mass of about 1000, so that its mechanical strength, heat resistance and other physical properties are lower than those of polyethylene wax products produced by ethylene polymerization.
An important application of oxidized polyethylene waxes is in PVC processing. Compared with fatty acid lubricants, it has no adverse effect on melt tension and Vicat softening temperature, and provides better anti-clogging and flow control effects. Oxidized polyethylene waxes can be used for controlled melting in special processing methods and are well compatible with other ingredients even when added in large quantities.
Oxidized polyethylene wax