Patent US4104459A successfully refreshed from Google Patents.
US4104459A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Treating polyvinyl chloride resins
Assignee: North Carolina National Bank NCNB
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Filing: 1976-03-25
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Granted: 1978-08-01
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Expires: 1996-03-25
Abstract
Abstract A method for reducing the vinyl chloride monomer content of polyvinyl chloride resins. The polyvinyl chloride-water slurry is placed in a vessel, and heat is applied to the vessel for a sufficient time to raise it to a suitable temperature for removal of vinyl chloride monomer from the resin. The resin slurry is agitated and also subjected to a vacuum to reduce the temperature during the heat stripping step. In a preferred method, the polvinyl chloride-water slurry is agitated in a closed vessel, heat is applied to rapidly heat the slurry to a temperature of at least about 50 DEG C, and vacuum is applied to the vessel. The slurry is then rapidly cooled by suitable means. The slurry is then dewatered and dried. Dried polyvinyl chloride resins produced by this process have been found to have a vinyl chloride monomer content below a detectable limit of about 2.0 ppm.
Inventors
- 👤 Edwin D. Hornbaker
- 👤 Adam Nugent, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 07:00
CPC Classifications
C; C08; C08F; C08F6/00; C08F6/001
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
66 words
In the method of treating particles of a polyvinyl chloride resin which have a susceptibility to degradation in dynamic thermal stability and an increase in bulk density upon prolonged heating, which have previously been subjected to a flashing step to remove a major portion of the unreacted vinyl chloride monomer therefrom, the improvement for further reducing the vinyl chloride monomer content of the resin particles comprising:
Claim 2
Dependent Claim
66 words
In the method of treating particles of a polyvinyl chloride resin which have a susceptibility to degradation in dynamic thermal stability and an increase in bulk density upon prolonged heating, which have previously been subjected to a flashing step to remove a major portion of the unreacted vinyl chloride monomer therefrom, the improvement for further reducing the vinyl chloride monomer content of the resin particles comprising:
Claim 3
Dependent Claim
145 words
a. suspending the resin particles in an aqueous medium in a closed vessel to form a resin-water slurry; b. indirectly applying heat to the slurry to maintain the temperature thereof in a range between about 50° C to about 95° C for a time period of from about one minute to about 120 minutes; c. applying a continuous vacuum in the range of from about 5 in. Hg to about 26 in. Hg to produce boiling of the slurry from the heat applied to the vessel while simultaneously removing from the vessel a vapor phase containing vinyl chloride monomer and the aqueous medium; and d. cooling the slurry to produce resin particles having a vinyl chloride monomer content of less than about 420 ppm (dry resin basis), a dynamic thermal stability of at least 7 minutes and a bulk density of at least 0.5 g/cc.
Claim 4
Dependent Claim
145 words
a. suspending the resin particles in an aqueous medium in a closed vessel to form a resin-water slurry; b. indirectly applying heat to the slurry to maintain the temperature thereof in a range between about 50° C to about 95° C for a time period of from about one minute to about 120 minutes; c. applying a continuous vacuum in the range of from about 5 in. Hg to about 26 in. Hg to produce boiling of the slurry from the heat applied to the vessel while simultaneously removing from the vessel a vapor phase containing vinyl chloride monomer and the aqueous medium; and d. cooling the slurry to produce resin particles having a vinyl chloride monomer content of less than about 420 ppm (dry resin basis), a dynamic thermal stability of at least 7 minutes and a bulk density of at least 0.5 g/cc.
Claim 5
Dependent Claim
44 words
The method of claim 1 wherein said temperature range is from about 60° C to about 90° C, said time period is from about 15 minutes to about 120 minutes, and said vacuum is from about 6 in. Hg to about 20 in. Hg.
Claim 6
Dependent Claim
22 words
The method of claim 1 including the steps of separating the resin particles from the aqueous medium and drying the resin particles.
Claim 7
Dependent Claim
18 words
The method of claim 1 wherein heat is applied to the slurry through the walls of the vessel.
Claim 8
Dependent Claim
21 words
The method of claim 1 wherein the polyvinyl chloride resin has a relative viscosity of from about 1.60 to about 2.50.
Claim 9
Dependent Claim
24 words
The method of claim 1 wherein the polyvinyl chloride resin has a relative viscosity in the range of from about 1.60 to about 1.85.
Claim 10
Dependent Claim
23 words
The method of claim 1 wherein the polyvinyl chloride resin has a relative viscosity in the range of about 2.00 to about 2.50.
Claim 11
Dependent Claim
31 words
The method of claim 6 wherein the polyvinyl chloride resin has a vinyl chloride monomer content of less than 220 parts per million after drying at 60° C for 1.25 hours.
Claim 12
Dependent Claim
31 words
The method of claim 6 wherein the polyvinyl chloride resin has a vinyl chloride monomer content of less than 2.0 parts per million after drying at 60° C for 1.25 hours.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-07-31 | 1982-01-30 | 1982-08-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-07-31 | 1986-01-30 | 1986-08-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-07-31 | 1990-01-30 | 1990-08-01 | $7700.00 | Window Closed / Lapsed |