Patent US3840392A successfully refreshed from Google Patents.
US3840392A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Coating asbestos-cement and the like
Assignee: Pennwalt Corp
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Filing: 1972-02-03
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Granted: 1974-10-08
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Expires: 1992-02-03
Abstract
Abstract Pigmented, in situ reduced zinc dichromate coatings on asbestoscement and similar surfaces are made more reproducible in color by including as at least a portion of the reducing agent a hexitol or pentitol such as sorbitol, or a low alkanolamine, or mixtures of these. An acid like phosphoric acid that forms a water-insoluble calcium salt but does not precipitate the zinc can also be added to the coating formulation.
Inventors
- 👤 L Schuster
- 👤 S Tongyai
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 14:53
CPC Classifications
C; C04; C04B; C04B41/00; C04B41/009; C04B41/45; C04B41/46; C04B41/48; C04B41/483; C04B41/4857; C04B41/50; C04B41/5007; C04B41/60; C04B41/61; C04B41/62; C04B41/63; C04B41/65; C09; C09D; C09D125/00; C09D125/02; C09D125/04; C09D125/08; C09D125/10
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
232 words
A METHOD OF COATING THE SURFACES OF A SERIES OF ASBESTOSCEMENT PLATES, WHICH METHOD IS CHARACTERIZED BY APPLYING TO THE SURFACES A COATING MIXTURE IN THE FORM OF AN AQUEOUS DISPERSION OF AN ACRYLIC OR THERMOSETTING BUTADIENE-STYRENE RESIN CONTAINING DISSOLVED ZINC DICHROMATE IN AN AMOUNT FROM ABOUT ONE TO ABOUT FIVE TIMES THE WEIGHT OF THE RESIN, A REDUCING AGENT IN AN AMOUNT THAT IS COMPATIBLE IN THE DISPERSION FOR AT LEAST ABOUT 2 HOURS AT ROOM TEMPERATURE BUT THAT CAUSES SUBSTANTIALLY COMPLETE REDUCTION OF THE CHROMIUM TO TRIVALENT CONDITION WHEN THE DISPERSION IS DRIED AND HEATED TO 180*C, AT LEAST ONE-THIRD OF THE REDUCING AGENT BEING A HEXITOL OR PENTITOL, AND AT LEAST ONE-THIRD OF THE REDUCING AGENT BEING A LOWER ALKANOLAMINE, THE MIXTURE ALSO INCLUDING IN DISPERSED CONDITION TIO2 PIGMENT IN A CONCENTRATION AT LEAST ONE-EIGHTH THE WEIGHT OF THE RESIN AND SUFFICIENT TOTAL PIGMENT TO BRING THE PIGMENT CONCENTRATION TO FORM ABOUT 16 PERCENT TO ABOUT 20 PERCENT OF THE CURED COATING WEIGHT, THE MIXTURE BEING APPLIED IN AN AMOUNT THAT AFTER CURING LEAVES A COATING WEIGHT BETWEEN ABOUT 1.5 AND 2.5 GRAMS PER SQUARE FOOT, HEATING THE COATED SURFACES TO A TEMPERATURE NO HIGHER THAN ABOUT 180*C FOR A FEW SECONDS TO PARTIALLY CURE THE COATING, AND THEN STACKING THE PLATES WITH THE HEATED SURFACE TO CAUSE THE CURING TO COMPLETE ITSELF WITHOUT THE FURTHER APPLICATION OF HEAT.
Claim 2
Independent Claim
232 words
A METHOD OF COATING THE SURFACES OF A SERIES OF ASBESTOSCEMENT PLATES, WHICH METHOD IS CHARACTERIZED BY APPLYING TO THE SURFACES A COATING MIXTURE IN THE FORM OF AN AQUEOUS DISPERSION OF AN ACRYLIC OR THERMOSETTING BUTADIENE-STYRENE RESIN CONTAINING DISSOLVED ZINC DICHROMATE IN AN AMOUNT FROM ABOUT ONE TO ABOUT FIVE TIMES THE WEIGHT OF THE RESIN, A REDUCING AGENT IN AN AMOUNT THAT IS COMPATIBLE IN THE DISPERSION FOR AT LEAST ABOUT 2 HOURS AT ROOM TEMPERATURE BUT THAT CAUSES SUBSTANTIALLY COMPLETE REDUCTION OF THE CHROMIUM TO TRIVALENT CONDITION WHEN THE DISPERSION IS DRIED AND HEATED TO 180*C, AT LEAST ONE-THIRD OF THE REDUCING AGENT BEING A HEXITOL OR PENTITOL, AND AT LEAST ONE-THIRD OF THE REDUCING AGENT BEING A LOWER ALKANOLAMINE, THE MIXTURE ALSO INCLUDING IN DISPERSED CONDITION TIO2 PIGMENT IN A CONCENTRATION AT LEAST ONE-EIGHTH THE WEIGHT OF THE RESIN AND SUFFICIENT TOTAL PIGMENT TO BRING THE PIGMENT CONCENTRATION TO FORM ABOUT 16 PERCENT TO ABOUT 20 PERCENT OF THE CURED COATING WEIGHT, THE MIXTURE BEING APPLIED IN AN AMOUNT THAT AFTER CURING LEAVES A COATING WEIGHT BETWEEN ABOUT 1.5 AND 2.5 GRAMS PER SQUARE FOOT, HEATING THE COATED SURFACES TO A TEMPERATURE NO HIGHER THAN ABOUT 180*C FOR A FEW SECONDS TO PARTIALLY CURE THE COATING, AND THEN STACKING THE PLATES WITH THE HEATED SURFACE TO CAUSE THE CURING TO COMPLETE ITSELF WITHOUT THE FURTHER APPLICATION OF HEAT.
Claim 3
Dependent Claim
33 words
The method of claim 1 in which the coating composition contains phosphoric acid in an amount by weight about one-fourth to about one-half the zinc dichromate content, and the heating temperature is 170*C.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-10-07 | 1978-04-08 | 1978-10-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-10-07 | 1982-04-08 | 1982-10-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-10-07 | 1986-04-08 | 1986-10-08 | $7700.00 | Window Closed / Lapsed |