Preparation method for lubricating oil pour point depressing type viscosity index improver

Abstract

The invention relates to a preparation method for a lubricating oil pour point depressing type viscosity index improver. The preparation method at least comprises the following processes including the degradation process, wherein ethylene-propylene copolymers are put into a reaction still containing hydrogenated base oil to be soaked and dissolved, then a depolymerizing agent is added to depolymerize the ethylene-propylene copolymers to obtain a depolymerization product; the grafting process, wherein the hydrogenated base oil is added to the depolymerization product again, and after temperature is adjusted, an initiator and methyl methacrylate are added to graft the depolymerization product to obtain a grafting product; the exhausting and viscosity adjusting process, wherein residual gas of the grafting product is removed, the hydrogenated base oil is added to the grafting product once again, and therefore the product is obtained. The lubricating oil pour point depressing type viscosity index improver prepared through the preparation method has the advantages of being proper in viscosity, good in low-temperature liquidity, low in shearing index, good in high-temperature oxidation stability and the like, and the requirements of high-grade large-span multi-stage lubricating oil for low-temperature power viscosity and boundary pumping temperature can be completely met.

Description

technical field [0001] The invention relates to a preparation method of a lubricating oil additive, in particular to a preparation method of a lubricating oil depreciating viscosity index improver. Background technique [0002] The viscosity of lubricating oil changes with the change of temperature. When the temperature difference is significant, the viscosity of lubricating oil shows a large difference. In order to improve the property that the viscosity of the lubricating oil changes greatly due to the change of temperature, that is, to make the lubricating oil have a higher viscosity index, it is necessary to add a viscosity index improver to the lubricating oil. The principle of the viscosity index improver is to use the high molecular polymer to dissolve in the lubricating oil. The molecular shape of the lubricant gradually stretches from curl, which expands the volume of the polymer and increases the internal friction between molecules, thus effectively increasing the...

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Problems solved by technology

[0006] (1) When the temperature rises, the ethylene-propylene copolymer is easy to stick and cause difficulty in stirring, making the grafted product uneven, and the grafting temperature of this patent is 70-400°C, so it is difficult to obtain uniform quality at such a high temperature The product;

[0007] (2) When preparing the recombinant lubricating oil viscosity index improver of this patent, the grafting process and the degradation process are carried out simultaneously, but the process conditions required for the grafting process and the degradation process are different. For the ethylene propylene copolymer with a larger molecular weight, The preparation method provided by this patent is difficult to obtain degradation products with suitable molecular weight;

[0008] (3) The patent does not set a process for discharging the residual gas generated at high temperature, so that the quality of the product obtained by using the preparation method of the patent is not high;

[0009] (4) The ethylene propylene copolymer and methacrylate of this patent are added in the hydrogenated base oil at the same time, and the grafting process is completed in one step. Although the process is simple, it does not take into account the adjustment of the quality of the intermediate product to obtain The product quality is better and the nature is more stable

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