US3607749A
Expired / Lapsed
US
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Viscosity index improvers
Assignee: BP PLC
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Filing: 1968-11-19
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Granted: 1971-09-21
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Expires: 1988-11-19
Abstract
Abstract Viscosity Index improvers for lubricating oils comprise a polymer of molecular weight above 100,000 e.g. a polymethacrylate, and a polymer of molecular weight below 25,000 e.g. a polyisobutylene. The low molecular weight polymer increases the shear-stability of high molecular weight polymer.
Inventors
- 👤 Eric Simon Forbes
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 02:31
CPC Classifications
C; C10; C10M; C10M143/00; C10M143/08; C10M143/06; C10M145/00; C10M145/02; C10M145/10; C10M145/12; C10M145/14; C10M2205/00; C10M2205/02; C10M2205/026; C10M2205/028; C10M2209/00; C10M2209/02; C10M2209/08; C10M2209/084
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
21 words
The lubricating composition of claim 1 in which the polyalkylmethacrylate viscosity index improver has a weight average molecular weight above 350,000
Claim 2
Dependent Claim
38 words
The lubricating composition of claim 2 which contains from about 1 percent to 10 percent by weight of the polyalkylmethacrylate viscosity index improver and from about 1 percent to 10 percent by weight of the substantially shear-stable polymer.
Claim 3
Dependent Claim
30 words
The lubricating composition of claim 3 in which the substantially shear-stable polymer is selected from the group consisting of poly-4-methylpentene-1 and polyisobutylene of weight average molecular weight below about 10,000.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-09-20 | 1975-03-22 | 1975-09-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-09-20 | 1979-03-22 | 1979-09-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-09-20 | 1983-03-22 | 1983-09-21 | $7700.00 | Window Closed / Lapsed |