Water-based wetness-indicating composition and sensor
View Patent ↗A color-appearing ink composition includes a surfactant blend of at least two non-ionic surfactants having hydrophilic-lipophilic balance values greater than 10, or a non-ionic surfactant having a hydrophilic-lipophilic balance value greater than 10 and a charged surfactant. The composition includes one or more water-insoluble leuco dyes, a developer and a desensitizer. The composition may be applied to a substrate to form a sensor.
1. A color-appearing ink composition comprising:
a surfactant blend comprising a nonionic surfactant having a hydrophilic-lipophilic balance value greater than 10, and a surfactant selected from the group consisting of Polyethylene Glycol Ester of Lauric Acid, Ethoxylated Alkyl Phenol, Polyoxyethylene Sorbitan Monooleate, Disodium Lauryl Phenyl Ether Disulfonate, and any combination thereof;
a water-insoluble leuco dye;
a developer;
a desensitizer comprising betaine or a betaine derivative;
a binder;
a stabilizer; and
water
wherein the composition is substantially free of organic solvent; and
wherein the composition develops color from a substantially non-colored state when contacted by an aqueous liquid.
2. The color-appearing ink composition of claim 1 wherein the developer is 4,4′-dihydroxybenzophenone.
3. The color-appearing ink composition of claim 1 wherein the desensitizer is a betaine derivative having an average molecular weight of 100 to 800.
4. The color-appearing ink composition of claim 1 wherein the binder is selected from the group consisting of water-based emulsions of water-insoluble polymers binders, cellulose derivatives, polyamides and their copolymers, polyesters and their copolymers, phenolic resins, and polyanhydrides.
5. The color-appearing ink composition of claim 1 wherein stabilizer is hydroxypropyl-modified guar gum.
6. The color-appearing ink composition of claim 1 , wherein the desensitizer comprising betaine or a betaine derivative is selected from the group consisting of: betaine, sodium bis-hydroxyethylglycinate lauryl-glucosides crosspolymer, sodium bis-hydroxyethylglycinate coco-glucosides crosspolymer, betaine ester-menthol, and betaine hydrocholoride.