Properties Of Low Molecular Polyisobutene

Brief introduction of polyisobutylene in lubricant and lube additive applications.

 

Polyisobutylene (PIB) is a colorless, odorless, non-toxic viscous liquid or semi-solid substance with chemical properties such as heat resistance, oxygen resistance, ultraviolet resistance, and acid & alkali resistance. Widely used in petroleum additives, fillers, adhesives, and blending improvements with other polymers.

For the lubricating oil and lube additives, low molecular weight polyisobutylene (PIB) is mainly used, such as PIB1000, PIB1300, and PIB2400.

 

Polyisobutylene (PIB) is one of the first Viscosity Index Improvers (VII) to be developed, In the 1930s, researchers at Standard Oil Company (now ExxonMobil) developed a process to produce PIB, which had better Viscosity Index improving properties.

 

PIB is the earliest viscosity index improver to be applied. The relative molecular mass of PIB used in Internal Combustion Engine (ICE) oil is about 50,000, and the relative molecular mass of hydraulic oil and gear oil is better at about 10,000. PIB has excellent shear stability (SI) and thermal oxidation stability, but because the polymer molecular chain has many methyl side chains, it is relatively rigid, and its viscosity increases rapidly at low temperatures, so the low-temperature performance is not good. It is limited in the production of multi-grade oils, and it cannot formulate low-viscosity grades (5W-30 and below) and large-span multi-grade oils.

 

PIB Preparation Reaction Formula

Polyisobutylene (PIB) is polymerized from C4 (butane-butene) fraction or high-purity isobutene raw material, which is cracked in refineries, and aluminum trichloride/tri-isobutyl aluminum or aluminum trichloride toluene/dichloroethane is used as Catalyst, selective polymerization at low temperature, refined product.

 

 

 

 

 

 

 

PIB is a liquid or semi-solid vinyl polymer formed by cationic polymerization of isobutylene, and the relative molecular weight of commercially available PIB is usually ranging from hundreds to millions.

 

According to the position of the C=C double bond, PIB is divided into two types: Highly Reactive Polyisobutylene (HRPIB) and conventional PIB. The global production of PIB in 2018 is about 1.1 million to 1.2 million tons. Mainly concentrated in North America, Europe, and Asia Pacific (mainly in South Korea, China, Japan, Malaysia, and India).

 

The main application of PIB is lubricating oil additives, accounting for 60% of PIB demand. In lubricating oil additives, PIB is mainly used as a raw material for the production of dispersants (the most commonly used relative molecular weights are 1000, 1300, and 2300); secondly, PIB has a higher viscosity and is used as a thickener to replace the traditional bright oil. Stroke engine oil, gear oil, grease, metalworking fluid, compressor fluid, and marine oil, etc., PIB is often used as a base oil. In addition to lubricating oil additives (which account for the majority), PIB can also be used in oil fuel additives, lubricant base oils, stretch films, sealants and adhesives, mining explosives, and cosmetics.