US4137388A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Polystyrene with distinct moieties of molecular weight distribution
Assignee: Braskem America Inc
•
Filing: 1978-01-06
•
Granted: 1979-01-30
•
Expires: 1998-01-06
Abstract
Abstract Crystal polystyrene with improved flow properties useful in injection molding is prepared in a two-stage process in which a first portion of monomer is polymerized in the presence of about 0.3 to about 2.0% peroxide initiator to convert about 70 to 95% of the monomer present to polymer having a number average molecular weight of 20,000 to 50,000 and a weight average of 50,000 to 100,000; then adding the rest of the monomer thereby reducing the catalyst concentration to generate a second moiety of polymer so that the final product has a weight average molecular weight of 150,000-300,000, and a number average of 50,000-70,000.
Inventors
- 👤 Louis A. Cutter
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 10:40
CPC Classifications
C; C08; C08F; C08F12/00; C08F12/02; C08F12/04; C08F12/06; C08F12/08; Y; Y10; Y10S; Y10S526/00; Y10S526/909; Y10S526/91
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
110 words
Method of making polystyrene having a bimodal molecular weight distribution by suspension polymerization comprising (a) polymerizing 100 parts by weight styrene in the presence of at least about 0.05 parts low-temperature peroxide initiator and at a temperature of from 80° C to 110° C to the point where at least about 70% of the styrene monomer is polymerized, (b) thereafter adding to the polymerization mixture about 100 to about 300 parts additional styrene and continuing to conduct the polymerization reaction in the presence of a high-temperature initiator and at a temperature of from 80° C to 150° C until residual monomer is less than about 0.5% of the polystyrene product.
Claim 2
Dependent Claim
110 words
Method of making polystyrene having a bimodal molecular weight distribution by suspension polymerization comprising (a) polymerizing 100 parts by weight styrene in the presence of at least about 0.05 parts low-temperature peroxide initiator and at a temperature of from 80° C to 110° C to the point where at least about 70% of the styrene monomer is polymerized, (b) thereafter adding to the polymerization mixture about 100 to about 300 parts additional styrene and continuing to conduct the polymerization reaction in the presence of a high-temperature initiator and at a temperature of from 80° C to 150° C until residual monomer is less than about 0.5% of the polystyrene product.
Claim 3
Dependent Claim
26 words
Method of claim 1 in which the initiator is present in step (a) in concentrations of about 0.3 to about 2.0 parts per 100 parts styrene.
Claim 4
Dependent Claim
12 words
Method of claim 1 in which the low-temperature initiator is benzoyl peroxide.
Claim 5
Dependent Claim
15 words
Method of claim 1 in which the temperature in step (a) is about 85-110° C.
Claim 6
Dependent Claim
22 words
Method of claim 1 in which the temperature is controlled during step (a) to maintain the initiator half-life at about 0.5-2 hours.
Claim 7
Dependent Claim
12 words
Method of claim 1 in which the high-temperature initiator is t-butyl perbenzoate.
References Cited (Backward Citations)
US2545702A
Cited
US2656334A
Cited
US2907756A
Cited
GB848620A
Cited
US3052664A
Cited
US3252950A
Cited
US3293233A
Cited
GB1243197A
Cited
US3726846A
Cited
US3817965A
Cited
US3726848A
Cited
US3681305A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-01-29 | 1982-07-31 | 1983-01-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-01-29 | 1986-07-31 | 1987-01-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-01-29 | 1990-07-31 | 1991-01-30 | $7700.00 | Window Closed / Lapsed |