Solid viscosity index improvers which provide excellent low temperature viscosity
US5278252A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 22, 1993 |
| Grant date | Jan 11, 1994 |
| Priority date | — |
| Expiry date | Mar 22, 2013 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC10M2205/06
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
A solid, cyclone-finishable polymer which does not exhibit cold flow and provides an unexpected balance of viscosity improving properties for oil compositions is produced by hydrogenating a copolymer comprising a homopolymer block of isoprene connected to a copolymer block of isoprene and a monoalkenyl aromatic hydrocarbon. The amount of the monoalkenyl aromatic hydrocarbon is sufficient to allow cyclone finishing although sufficiently distributed to provide oil compositions having good low temperature viscosity. Prior to hydrogenation, the copolymers have a number average molecular weight between 125,000 and 275,000, preferably 150,000 to 240,000, and a total monoalkenyl aromatic content between 10 and 2 percent by weight, preferably between 7 and 3 percent. The copolymer is hydrogenated to substantially saturate the isoprene and to reduce the size of monoalkenyl aromatic segments in the copolymer block.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.