US4728712A
Expired / Lapsed
US
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Method of producing mercaptan terminated polymers with increased reactivity and reduced odor
Assignee: PRC Desoto International Inc
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Filing: 1985-06-11
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Granted: 1988-03-01
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Expires: 2005-06-11
Abstract
Abstract A method for producing mercaptan terminated liquid polymers with increased chemical reactivity and reduced odor is disclosed which involves heating the polymeric liquid material under conditions which avoid oxidation and depolymerization of the material while removing at least 50 weight percent of low molecular weight mercaptan compounds to produce a stripped polymer material having an increased cure rate and reduced obnoxious mercaptan odor.
Inventors
- 👤 Hakam Singh
- 👤 Jack W. Hutt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 03:51
CPC Classifications
C; C08; C08G; C08G18/00; C08G18/06; C08G18/83; C08G18/834; C08G18/835; C08G65/00; C08G65/02; C08G65/30; C08G75/00; C08G75/02; C08G75/04; C08G75/045; C08G85/00; C08G85/002
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
139 words
A method for increasing the cure rate of a liquid mercaptan terminated polymer to a solid elastomer, said liquid mercaptan terminated polymer containing from about 0.5 weight percent to about 3 weight percent low molecular weight mercaptan compounds having a molecular weight of less than about 300 and having an obnoxious smell, said method comprising the steps of: heating said mercaptan terminated polymer at about 135° to 175° C. and for a sufficient length of time to vaporize at least about 50 weight percent of said low molecular weight obnoxious semlling mercaptan containing compounds, but not to decompose said liquid mercaptan terminated polymer, to thereby obtain a stripped liquid mercaptan terminated polymer having an increased cure rate and a reduced obnoxious mercaptan odor; separating the vapor containing low molecular weight mercaptan compounds from said stripped liquid mercaptan terminated polymer.
Claim 2
Independent Claim
139 words
A method for increasing the cure rate of a liquid mercaptan terminated polymer to a solid elastomer, said liquid mercaptan terminated polymer containing from about 0.5 weight percent to about 3 weight percent low molecular weight mercaptan compounds having a molecular weight of less than about 300 and having an obnoxious smell, said method comprising the steps of: heating said mercaptan terminated polymer at about 135° to 175° C. and for a sufficient length of time to vaporize at least about 50 weight percent of said low molecular weight obnoxious semlling mercaptan containing compounds, but not to decompose said liquid mercaptan terminated polymer, to thereby obtain a stripped liquid mercaptan terminated polymer having an increased cure rate and a reduced obnoxious mercaptan odor; separating the vapor containing low molecular weight mercaptan compounds from said stripped liquid mercaptan terminated polymer.
Claim 3
Independent Claim
150 words
A method for increasing cure rate of a liquid mercaptan terminated polymer to a solid elastomer, said liquid mercaptan terminated polymer containing from about 0.5 weight percent to about 3 weight percent of low molecular weight mercaptan compounds having a molecular weight less than about 300 and having an obnoxious smell, said method comprising the steps of: forming a film of said liquid mercaptan terminated polymer having a thickness of less than about 6 mm; heating said film to a sufficient temperature and for a sufficient length of time to vaporize at least about 50 weight percent of said low molecular weight obnoxious smelling mercaptan compounds, but not decomposing said liquid mercaptan terminated polymer, thereby obtaining a stripped liquid mercaptan terminated polymer having an increased cure rate and a reduced obnoxious mercaptan odor; and separating the vapor containing low molecular weight mercaptan compounds from said stripped liquid mercaptan terminated polymer.
Claim 4
Independent Claim
150 words
A method for increasing cure rate of a liquid mercaptan terminated polymer to a solid elastomer, said liquid mercaptan terminated polymer containing from about 0.5 weight percent to about 3 weight percent of low molecular weight mercaptan compounds having a molecular weight less than about 300 and having an obnoxious smell, said method comprising the steps of: forming a film of said liquid mercaptan terminated polymer having a thickness of less than about 6 mm; heating said film to a sufficient temperature and for a sufficient length of time to vaporize at least about 50 weight percent of said low molecular weight obnoxious smelling mercaptan compounds, but not decomposing said liquid mercaptan terminated polymer, thereby obtaining a stripped liquid mercaptan terminated polymer having an increased cure rate and a reduced obnoxious mercaptan odor; and separating the vapor containing low molecular weight mercaptan compounds from said stripped liquid mercaptan terminated polymer.
Claim 5
Dependent Claim
24 words
A method according to claim 2 wherein a vacuum is applied to said film during vaporization of said low molecular weight mercaptan containing compounds.
Claim 6
Dependent Claim
22 words
A method according to claim 3 wherein the vacuum applied to the film is between 1 mm Hg and 100 mm Hg.
Claim 7
Dependent Claim
27 words
A method according to claim 4 wherein the temperature to which the film of liquid mercaptan terminated polymer is heated is between room temperature and 200° C.
Claim 8
Dependent Claim
26 words
A method according to claim 5 wherein the temperature to which the film of liquid mercaptan terminated polymer is heated between 135° C. and 175° C.
Claim 9
Dependent Claim
20 words
A method according to claim 2 wherein said film has a thickness of between about 1 mm and 6 mm.
Claim 10
Dependent Claim
56 words
A method according to claim 2 including, prior to forming a film of said liquid mercaptan terminated polymer having a thickness of less than about 6 mm., the additional step of mixing an organic solvent for said liquid mercaptan terminated polymer with said liquid mercaptan terminated polymer to provide a lower viscosity polymer containing said solvent.
Claim 11
Dependent Claim
62 words
A method according to claim 8 wherein said organic solvent which is mixed with said liquid mercaptan terminated polymer to provide a lower viscosity polymer containing said organic solvent has a boiling point at atmospheric pressure which is at or below, but not more than 50° C. below, the temperature to which said film formed from said lower viscosity polymer is heated.
Claim 12
Dependent Claim
24 words
A method according to claim 2 wherein the step of separating said vapors includes contacting said film with a flowing stream of inert gas.
Claim 13
Dependent Claim
21 words
A method according to claim 10 wherein said inert gas is selected from the group consisting of nitrogen and carbon dioxide.
Claim 14
Dependent Claim
31 words
A method according to claim 8 wherein the range of organic solvent mixed with the liquid mercaptan terminated polymer is between 10-35 percent by weight of said liquid mercaptan terminated polymer.
Claim 15
Dependent Claim
33 words
A method according to claim 8 wherein said organic solvent is selected from the group consisting of xylene, toluene and aromatic naphthas having a boiling point of between 100° C. and 150° C.
Claim 16
Dependent Claim
78 words
A method according to claim 8 wherein said film is formed by continually flowing said lower viscosity polymer over a surface from an upstream end of said surface to a downstream end of said surface, wherein said heating and vaporization of said low molecular weight mercaptan compounds occur between said upstream and downstream ends to form said stripped polymer and wherein said method includes the step of collecting said stripped polymer as it flows from said downstream end.
Claim 17
Dependent Claim
46 words
A method according to claim 14 where the temperature of the liquid polymer film is between about 100° and 200° C., the vacuum applied is between about 1 mm and 100 mm Hg, and the polymer film thickness is between about 1 mm to 6 mm.
Claim 18
Dependent Claim
33 words
A method according to claim 15 wherein the time it takes the lower viscosity polymer to flow from said upstream end of said surface to said downstream end is less than 1 minute.
Claim 19
Dependent Claim
23 words
A method according to claim 16 wherein a vertical cylindrical wiped film evaporator is used to carry out the steps of the invention.
Claim 20
Dependent Claim
20 words
A method accroding to claim 1 wherein the molecular weight of said liquid mercaptan terminated polymer is above about 1,000.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-03-01 | 1991-08-31 | 1992-03-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-03-01 | 1995-08-31 | 1996-03-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-03-01 | 1999-08-31 | 2000-03-01 | $7700.00 | Window Closed / Lapsed |