US4008361A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Removal of residual vinyl halide monomer from vinyl halide polymers by radio frequency dielectric heating
Assignee: BP PLC
•
Filing: 1975-12-11
•
Granted: 1977-02-15
•
Expires: 1995-12-11
Abstract
Abstract The residual vinyl halide content of vinyl halide polymer is reduced by radiofrequency dielectric heating of a water-containing layer of particulate polymer over which is disposed a layer of material through which vinyl chloride can pass but which restricts the passage of water e.g. perforated plastic sheet.
Inventors
- 👤 Anthony John Park
- 👤 Brian Weeks
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 08:00
CPC Classifications
C; C08; C08J; C08J3/00; C08J3/28; C08F; C08F6/00; C08F6/001; C08J2327/00; C08J2327/02
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
102 words
The process for reducing the vinyl halide residual monomer content of a polymer containing vinyl halide monomer which comprises heating a water-containing layer of the polymer in particulate form in a zone of radiofrequency dielectric heating in which zone a layer of material through which vinyl chloride can pass but which restricts the passage of water vapour, and which is substantially transparent to the radiofrequency used to heat the polymer, is disposed over the surface of the layer of the polymer so as to reduce evaporation of water from the layer of polymer during the dielectric heating, and recovering the particulate polymer.
Claim 2
Dependent Claim
102 words
The process for reducing the vinyl halide residual monomer content of a polymer containing vinyl halide monomer which comprises heating a water-containing layer of the polymer in particulate form in a zone of radiofrequency dielectric heating in which zone a layer of material through which vinyl chloride can pass but which restricts the passage of water vapour, and which is substantially transparent to the radiofrequency used to heat the polymer, is disposed over the surface of the layer of the polymer so as to reduce evaporation of water from the layer of polymer during the dielectric heating, and recovering the particulate polymer.
Claim 3
Dependent Claim
20 words
The process according to claim 1 wherein any copolymerised monomer constitutes not more than 30% by weight of the polymer.
Claim 4
Dependent Claim
14 words
The process according to claim 2 wherein the polymer is vinyl halide polymer resin.
Claim 5
Dependent Claim
35 words
The process according to claim 3 wherein the vinyl halide polymer subjected to radiofrequency dielectric heating is in the particulate form in which it is recovered from the polymerisation process in which it was produced.
Claim 6
Dependent Claim
25 words
The process according to claim 4 wherein the polymer subjected to radio frequency dielectric heating is in the form of beads recovered from suspension polymerisation.
Claim 7
Dependent Claim
26 words
The process according to claim 1 wherein the polymer contains at least 5% by weight of water, based on dry polymer when the dielectric heating begins.
Claim 8
Dependent Claim
28 words
The process according to claim 6 wherein the vinyl halide polymer contains at least 10% by weight of water, based on dry polymer, when the dielectric heating begins.
Claim 9
Dependent Claim
26 words
The process according to claim 7 wherein the polymer contains up to 30% by weight of water, based on dry polymer, where the dielectric heating begins.
Claim 10
Dependent Claim
22 words
The process according to claim 1 wherein the layer of material which restricts the passage of water vapour is a plastic sheet.
Claim 11
Dependent Claim
12 words
The process according to claim 9 wherein the plastic sheet is perforated.
Claim 12
Dependent Claim
25 words
The process according to claim 10 wherein the combined area of the perforations is not more than 0.1% of the area of the plastic sheet.
Claim 13
Dependent Claim
44 words
The process according to claim 9 wherein the water-containing layer of the polymer is conveyed continuously through the dielectric heating zone under conditions such that not more than 10% by weight of the water initially present in the polymer evaporates during the dielectric heating.
Claim 14
Dependent Claim
16 words
The process according to claim 1 wherein the dielectric heating is carried out by microwave radiation.
Claim 15
Dependent Claim
20 words
The process according to claim 13 wherein the microwave radiation has a frequency in the range 900 to 30,000 MHz.
Claim 16
Dependent Claim
25 words
The process according to claim 13 wherein the exposure time of the polymer to dielectric heating is in the range 0:1 seconds to 100 minutes.
Claim 17
Dependent Claim
16 words
The process according to claim 15 wherein the exposure time is 1 second to 50 minutes.
Claim 18
Dependent Claim
32 words
The process according to claim 13 wherein the polymer is exposed to dielectric heating for a time such that the polymer reaches a temperature in the range 70° C to 100° C.
Claim 19
Dependent Claim
34 words
The process according to claim 13 wherein the polymer is exposed to dielectric heating for a time such that the polymer leaving the dielectric heating zone contains at least 5% by weight of water.
References Cited (Backward Citations)
GB1226988A
Cited
GB1277609A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-02-15 | 1980-08-16 | 1981-02-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-02-15 | 1984-08-16 | 1985-02-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-02-15 | 1988-08-16 | 1989-02-15 | $7700.00 | Window Closed / Lapsed |