US3737488A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for producing moulded foams from rubber latices by using microwave heating
Assignee: International Synthetic Rubber Co Ltd
•
Filing: 1970-06-30
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Granted: 1973-06-05
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Expires: 1990-06-30
Abstract
Abstract A process for preparing a moulded foam comprises subjecting a foamed curable rubber latex composition containing a delayed action or heat sensitive gelling system in a closed mould to radiation of radio frequency, preferably of a frequency at least 20 mc/sec and in one embodiment of the invention at least 800 mc/sec, of an intensity and for a duration to cause gelling and thereafter curing the gelled foam to a solid foamed article. The invention is very applicable to the preparation of foamed articles from a filled latex of an emulsion polymerized styrenebutadiene rubber.
Inventors
- 👤 D Porter
- 👤 W Campbell
- 👤 E Duck
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 08:19
CPC Classifications
C; C08; C08J; C08J9/00; C08J9/36; C08J9/30; C08J2321/00; Y; Y10; Y10S; Y10S264/00; Y10S264/46; Y10S521/00; Y10S521/915
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
21 words
A process according to claim 1 wherein a sodium salt of a carboxy methyl cellulose is included in the latex composition.
Claim 2
Dependent Claim
21 words
A process according to claim 2 wherein the sodium salt is used in an amount of from 0.03 to 5.0 phr.
Claim 3
Dependent Claim
17 words
A process according to claim 1 wherein the delayed action gelling system comprises sodium or potassium silicofluoride.
Claim 4
Dependent Claim
24 words
A process according to claim 1 wherein the amount of gelling agent in the gelling system is in the range 1.00 to 4.00 phr.
Claim 5
Dependent Claim
16 words
A process according to claim 1 wherein the mould used is made of a non-conducting material.
Claim 6
Dependent Claim
26 words
A process according to claim 1 wherein the mould used is made of wood, glass fibre reinforced polyester, reinforced phenolic resin or a mixture of these.
Claim 7
Dependent Claim
18 words
A process according to claim 1 wherein the mould is heated prior to filling with the latex composition.
Claim 8
Dependent Claim
20 words
A process according to claim 1 wherein the frequency of the microwave is in the range 800 to 2,500 mc/sec.
Claim 9
Dependent Claim
22 words
A process according to claim 1 wherein the intensity of the radiation is 0.5 to 5.0 Kw per kilogramme of latex composition.
Claim 10
Dependent Claim
22 words
A process according to claim 10 wherein the intensity of the radiation is 1.5 to 2.3 Kw per kilogramme of latex composition.
Claim 11
Dependent Claim
23 words
A process according to claim 1 wherein the rubber latex is a synthetic latex prepared in emulsion using one or more anionic emulsifiers.
Claim 12
Dependent Claim
35 words
A process according to claim 1 wherein the mould used is made of a material having a loss factor lower than the loss factor of the latex composition measured at the frequency of the radiation.
Claim 13
Dependent Claim
14 words
A process according to claim 1 wherein there is included an alkali metal halide.
Claim 14
Dependent Claim
12 words
A process according to claim 2 wherein the halide is potassium chloride.
Claim 15
Dependent Claim
19 words
A process according to claim 1 wherein up to 75 phr of filler is included in the latex composition.
Claim 16
Dependent Claim
15 words
A process according to claim 16 wherein 20 to 40 phr of filler is included.
Claim 17
Dependent Claim
24 words
A modification of the process claimed in claim 1 wherein the delayed action gelling system is wholly or partly a heat sensitive gelling system.
Claim 18
Dependent Claim
16 words
A process according to claim 18 wherein the gelling system comprises zinc oxide and ammonium acetate.
Claim 19
Dependent Claim
14 words
A process according to claim 1 wherein gelling occurs in 5 to 15 seconds.
Claim 20
Dependent Claim
28 words
A process according to claim 1 wherein the rubber latex is reinforced with a non-rubber latex selected from the group consisting of polystyrene latex and polyvinyl chloride latex.
Claim 21
Dependent Claim
25 words
A process according to claim 21 wherein the nonrubber latex is present in an amount of up to 50 phr on a dry weight basis.
References Cited (Backward Citations)
US2261439A
Cited
US2441548A
Cited
US2484434A
Cited
US2604666A
Cited
US2659703A
Cited
US2512464A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-06-04 | 1976-12-04 | 1977-06-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-04 | 1980-12-04 | 1981-06-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-04 | 1984-12-04 | 1985-06-05 | $7700.00 | Window Closed / Lapsed |