Chemical indicator compositions, indicators and methods
Assignee3M Innovative Properties Company
InventorsDavid A. Whitman, David M. Read, Ranjani V. Parthasarathy, Kevin D. Landgrebe, Anthony E. Bennett
Life of this patent
Estimating the term…
Abstract
Chemical indicator compositions comprising a bismuth compound; elemental sulfur; and a compound with relatively high water solubility which makes the composition alkaline when exposed to water vapor at an elevated temperature; a chemical indicator comprising a substrate and the composition coated on at least a portion of a major surface of the substrate; and methods of making and using the chemical indicator are disclosed.
Claims19
A chemical indicator composition comprising:
- a) a bismuth (III) compound comprising at least one organic group which includes 2 to 20 carbon atoms;
- b) elemental sulfur;
- and
- c) a reducing agent selected from the group consisting of ascorbic acid and its derivatives, tocopherols, gallates, t-butyl hydroquinones, napthylamines, polyphenols, and combinations thereof;
- and
- d) a compound which makes the composition alkaline when exposed to water vapor at an elevated temperature.
A chemical indicator composition comprising:
- a) a bismuth (III) compound comprising at least one organic group which includes 2 to 20 carbon atoms;
- b) elemental sulfur;
- and
- c) a compound which makes the composition alkaline when exposed to water vapor at an elevated temperature and is selected from the group consisting of potassium carbonate, potassium bicarbonate, and sodium phosphate.
A chemical indicator composition comprising:
- a) a bismuth (III) compound comprising at least one organic group which includes 2 to 20 carbon atoms;
- b) elemental sulfur;
- c) a compound that makes the composition alkaline when exposed to water vapor at an elevated temperature;
- wherein the compound has a solubility in water at 20° C. of more than 5 grams/100 ml;
- and
- d) a reducing agent selected from the group consisting of tocopherols, napthylamines, polyphenols and combinations thereof.
Dependencies are inferred from the claim text.