Sulfurized isobutylene

Sulfurized isobutylene (CAS 68511-50-2) is an organosulfur additive used to enhance the extreme-pressure and anti-wear performance of lubricant formulations. It functions by forming a protective sulfide film on metal surfaces.

Under high-load conditions, this film prevents scuffing, welding, and premature wear in demanding mechanical systems. In gear oils, hydraulic fluids, and metalworking fluids, it provides extreme-pressure protection during heavy-load machining.

It is particularly effective in cutting and forming operations where conventional additives fail. Grease formulations for industrial and automotive applications incorporate it to extend component life in high-temperature environments.

This includes high-contact-stress environments such as CV joints and open gears. It is also used in engine oil additive packages and transmission fluids where oxidation control and boundary lubrication are required simultaneously.

In the oil and gas sector, it protects drilling fluid systems and downhole equipment subjected to severe mechanical stress. Sulfurized isobutylene is supplied as a liquid, typically in varying active sulfur content grades.

These grades range from approximately 40% to over 50% sulfur by weight. Both active and inactive sulfur variants are available, with the distinction being commercially significant for specific industrial applications.

Active grades offer higher EP performance while inactive grades are preferred where corrosion to copper alloys must be controlled. It is available in technical grade for industrial lubricant and additive manufacturing.