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US 8,871,994 B2Granted
Wetness sensor for use in an absorbent article
AssigneeKimberly-Clark Worldwide, Inc.
InventorsNing Wei, Xuedong Song
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AssigneeKimberly-Clark Worldwide, Inc.
InventorsNing Wei, Xuedong Song
Estimating the term…
A wetness sensor for an absorbent article that is formed from an ink is provided. The ink includes a proton-accepting chromogen and a proton-donating agent (or color developer). Prior to use, the ink is generally dry and in a protonated form so that it has a visible color. However, upon contact with bodily fluids (e.g., urine, fecal matter, mucus, menses, vaginal fluid, etc.), water in the fluid can lead to deprotonation of the chromogen, thereby resulting in a shift of the absorption maxima of the chromogen towards either the red (“bathochromic shift”) or blue end of the spectrum (“hypsochromic shift”). To increase the rate of the color change during use, the proton-donating agent is an aliphatic carboxylic acid that is highly soluble in the bodily fluid (e.g., urine), and therefore results in a color change that is very rapid and may be detected within a relatively short period of time.
An absorbent article comprising:
An absorbent article comprising a wetness sensor that includes an ink disposed on a substrate, wherein the ink comprises a leuco dye and a proton-donating agent, the proton-donating agent including an aliphatic carboxylic acid having a solubility in water of greater than about 5 grams per 100 milliliters of water at a temperature of 20° C. and a first acid dissociation constant of from about 0 to about 8, the weight ratio of the proton-donating agent to the leuco dye being from about 0.4 to about 10, wherein the ink undergoes a visible color change upon contact with an aqueous fluid, further wherein the ink is free of wetting agents.
A wetness sensor for an absorbent article that comprises an ink disposed on a substrate, wherein the ink comprises a leuco dye and a proton-donating agent, the proton-donating agent including an aliphatic carboxylic acid having a solubility in water of greater than about 5 grams per 100 milliliters of water at a temperature of 20° C. and a first acid dissociation constant of from about 0 to about 8, the weight ratio of the proton-donating agent to the leuco dye being from about 0.4 to about 10, wherein the ink undergoes a visible color change upon contact with an aqueous fluid, further wherein the ink is free of wetting agents.
Dependencies are inferred from the claim text.