Star-type viscosity index improver will take you to quickly understand the function and performance of viscosity index improvers

What is a viscosity index improver?

★ Viscosity index improver is one of the indispensable additives for multi-grade engine oil, and its proportion is second only to detergent and dispersant. The viscosity index improver has been developed from the original polyisobutylene (PIB) to polymethacrylate (PMA), ethylene-propylene copolymer (OCP), and styrene isoprene copolymer (HSD). The function of the viscosity index improver is to improve the viscosity-temperature performance of the oil, so that the oil has a higher viscosity index, so as to ensure that the engine can start smoothly at low temperature, and the oil has a large enough viscosity at high temperature to ensure good lubricating.

Performance of viscosity index improvers

★ The use performance of the viscosity index improver is mainly reflected in the thickening performance, low-temperature performance, and shear resistance performance of refined oil.

Thickening force

★ The thickening ability of the viscosity index improver is mainly related to the type and molecular weight of the viscosity index improver. The larger the molecular weight, the stronger the thickening ability. The thickening ability of the viscosity index improver determines the amount of viscosity index improver added to the multigrade engine oil. Due to the thermal oxidative decomposition of polymer compounds, the amount of viscosity index improver added has a significant effect on the detergency of multi-grade engine oils.

Low temperature performance

★ The low-temperature performance of multi-grade engine oil is mainly reflected in low-temperature start-up and low-temperature pumping. On CCS (cold start simulator), it can reflect the apparent viscosity of multi-grade oil when the engine is started, so as to predict the minimum starting temperature of the engine . After the engine is started, the oil pressure of the lubricating system must be normalized in a very short time, so as to ensure that all friction points of the engine are lubricated in a timely and sufficient manner, that is, the lubricating oil must have good low-temperature pumping performance, which can be used in small Rotational viscometer MRV measurement.

Shear Stability

★ Shear stability is an important performance of viscosity index improver, which directly affects the stability of multi-stage engine oil viscosity. Shear stability is related to the molecular weight, molecular weight distribution and polymer structure of viscosity index improver, but mainly determined by the molecular weight. The larger the molecular weight of the same type of viscosity index improver, the worse the shear stability.

★There are several ways to improve shear stability:

①Reduce the molecular weight of the viscosity index improver and narrow the molecular weight distribution;

②By improving the structural stability of the polymer, so that the polymer has better shear stability while maintaining a high thickening capacity.

Kunvii invented the patented modification technology and developed a new star-shaped viscosity modifier

★ Infineum’s star polymer SV260 is a typical example of performance improvement. This product performs well in terms of thickening performance and shear stability. Kunvii® adopts international advanced synthetic rubber + patented modification technology; The new star-shaped viscosity index agent produced makes the comprehensive performance of the viscosity index improver reach or exceed Infineum’s SV260, which is recognized and used by the world’s top 500 oil companies and many listed companies in the industry.

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