US4421719A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Colorimetric indicators
Assignee: 3M Co
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Filing: 1981-10-08
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Granted: 1983-12-20
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Expires: 2001-10-08
Abstract
Abstract A colorimetric indicator in sheet form comprising an indicator substance, a high surface area carrier for said indicator substance, and a self-adhering clay mineral binder coated on a backing is disclosed. The colorimetric indicator is useful for personal monitors, as end of service life indicators for respirators, thin layer chromatography plates, and vapor transfer sheets.
Inventors
- 👤 Malcolm B. Burleigh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 06:21
CPC Classifications
G; G01; G01N; G01N30/00; G01N30/90; G01N30/95; G01N31/00; G01N31/22; Y; Y10; Y10T; Y10T436/00; Y10T436/18; Y10T436/186; Y10T436/20; Y10T436/203332; Y10T436/204165
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
145 words
A colorimetric indicator in sheet form for the monitoring of a hazardous substance in ambient air comprising a flexible, non-adhesive bearing, organic film backing on wich is coated a colorimetric indicator consisting essentially of a. an indicator substance selected from permanganate salts, b. a high surface area carrier for said indicator substance selected from the group consisting of alumina and silica, and c. a self-adhering bentonite clay mineral binder, said colorimetric indicator upon exposure to said hazardous substance undergoing an irreversible chemical reaction which progresses, as a function of diffusion, through the depth of the colorimetric indicator resulting in a visually resolvable color change, the rate of said reaction being proportional to the amount of said indicator substance present and the concentration of said hazardous substance to be monitored, said color change indicating that exposure to said hazardous substance has reached a selected time-weighted-average value.
Claim 2
Dependent Claim
145 words
A colorimetric indicator in sheet form for the monitoring of a hazardous substance in ambient air comprising a flexible, non-adhesive bearing, organic film backing on wich is coated a colorimetric indicator consisting essentially of a. an indicator substance selected from permanganate salts, b. a high surface area carrier for said indicator substance selected from the group consisting of alumina and silica, and c. a self-adhering bentonite clay mineral binder, said colorimetric indicator upon exposure to said hazardous substance undergoing an irreversible chemical reaction which progresses, as a function of diffusion, through the depth of the colorimetric indicator resulting in a visually resolvable color change, the rate of said reaction being proportional to the amount of said indicator substance present and the concentration of said hazardous substance to be monitored, said color change indicating that exposure to said hazardous substance has reached a selected time-weighted-average value.
Claim 3
Dependent Claim
15 words
The colorimetric indicator according to claim 1 wherein the high surface area carrier is silica.
Claim 4
Dependent Claim
15 words
The colorimetric indicator according to claim 1 wherein the high surface area carrier is alumina.
Claim 5
Dependent Claim
15 words
The colorimetric indicator according to claim 1 wherein the backing is a transparent polyester film.
Claim 6
Dependent Claim
127 words
A colorimetric indicator in sheet form for the detection of fluid substances comprising a flexible, non-adhesive-bearing, organic film backing on which is coated a colorimetric indicator consisting essentially of a. an indicator substance selected from permanganate salts, b. a high surface area carrier for said indicator substance selected from the group consisting of alumina and silica, and c. a self-adhering bentonite clay mineral binder, said colorimetric indicator upon exposure to said fluid substance to be detected undergoing an irreversible chemical reaction which progresses, as a function of diffusion, through the depth of the colorimetric indicator resulting in a visually resolvable color change, the rate of said change being proportional to the amount of said indicator substance present and the concentration of said fluid substance to be detected.
Claim 7
Dependent Claim
127 words
A colorimetric indicator in sheet form for the detection of fluid substances comprising a flexible, non-adhesive-bearing, organic film backing on which is coated a colorimetric indicator consisting essentially of a. an indicator substance selected from permanganate salts, b. a high surface area carrier for said indicator substance selected from the group consisting of alumina and silica, and c. a self-adhering bentonite clay mineral binder, said colorimetric indicator upon exposure to said fluid substance to be detected undergoing an irreversible chemical reaction which progresses, as a function of diffusion, through the depth of the colorimetric indicator resulting in a visually resolvable color change, the rate of said change being proportional to the amount of said indicator substance present and the concentration of said fluid substance to be detected.
Claim 8
Dependent Claim
12 words
The colorimetric indicator according to claim 5 wherein the carrier is silica.
Claim 9
Dependent Claim
12 words
The colorimetric indicator according to claim 5 wherein the carrier is alumina.
Claim 10
Dependent Claim
15 words
The colorimetric indicator according to claim 5 wherein the backing is a transparent polyester film.
Claim 11
Dependent Claim
58 words
A thin layer chromatography plate comprising a colorimetric indicator coated on a flexible, non-adhesive-bearing, organic film backing, said colorimetric indicator consisting essentially of a. an indicator substance selected from permanganate salts, b. a high surface area carrier for said indicator substance selected from the group consisting of alumina and silica, and c. a self-adhering bentonite clay mineral binder.
Claim 12
Dependent Claim
58 words
A thin layer chromatography plate comprising a colorimetric indicator coated on a flexible, non-adhesive-bearing, organic film backing, said colorimetric indicator consisting essentially of a. an indicator substance selected from permanganate salts, b. a high surface area carrier for said indicator substance selected from the group consisting of alumina and silica, and c. a self-adhering bentonite clay mineral binder.
Claim 13
Dependent Claim
57 words
A vapor transfer sheet comprising a colorimetric indicator coated on a flexible, non-adhesive-bearing, organic film backing, said colorimetric indicator consisting essentially of a. an indicator substance selected from permanganate salts, b. a high surface area carrier for said indicator substance selected from the group consisting of alumina and silica, and c. a self-adhering bentonite clay mineral binder.
Claim 14
Dependent Claim
57 words
A vapor transfer sheet comprising a colorimetric indicator coated on a flexible, non-adhesive-bearing, organic film backing, said colorimetric indicator consisting essentially of a. an indicator substance selected from permanganate salts, b. a high surface area carrier for said indicator substance selected from the group consisting of alumina and silica, and c. a self-adhering bentonite clay mineral binder.
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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) | 1986-12-19 | 1987-06-20 | 1987-12-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-12-19 | 1991-06-20 | 1991-12-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-12-19 | 1995-06-20 | 1995-12-20 | $7700.00 | Window Closed / Lapsed |