Color-changing materials and multiple component materials having a color-changing composition

1. A color-changing material comprising:

a hydrogel-forming composition comprising a charged hydrogel-forming polymer, the hydrogel-forming composition containing at least one charged species;

a charged colorant;

a pH adjuster; and

a volatile solvent;

wherein the charged hydrogel-forming polymer is selected from poly(ethylene glycol)-grafted cationic hydrogels; a copolymer of 2-hydroxyethyl methacrylate (HEMA) and methacrylamide propyltrimethylammonium chloride; a crosslinked cationic copolymer of vinylpyrrolidone (VP) and 3-dimethylaminopropyl(meth)acrylamide (DMAPMA) monomer; (3-acrylamidopropyl)-trimethylammonium chloride (APTMAC1) monomer crosslinked with a neutral crosslinker N,N-methylenebisacrylamide; crosslinked hydrophobically-modified dialkyldiallylammonium salts; a vinyl ether of monoethanolamine; and copolymerization of N,N,N,N-tetrallyl piperazinium dibromide (TAP) with N,N-diallyl morpholinium bromide (DAM).

2. The color-changing material of claim 1 , further comprising a neutral hydrogel-forming polymer selected from polyethylene oxide, polyAMPS, polyvinylpyrrolidone, polyacrylamide, polyvinyl alcohol, sodium polyacrylate, agarose, methylcellulose and hylaronan.

3. The color-changing material of claim 1 , wherein the color-changing material includes more than one charged colorant.

4. The color-changing material of claim 1 , wherein the charged colorant is a pH indicator having a color transition pH of greater than 9.

5. The color-changing material of claim 1 , wherein the charged colorant is a pH indicator having a color transition pH of less than 5.5.

6. The color-changing material of claim 1 , wherein the volatile solvent is selected from water, low alcohol, acetone, tetrahydrofuran and mixtures of these volatile solvents.

7. A multiple-component material, the material comprising:

a substrate, the substrate having a hydrogel-forming layer, wherein the hydrogel-forming layer includes a color-changing composition, the color-changing composition comprising

a hydrogel-forming composition comprising a charged hydrogel-forming polymer;

a charged colorant;

a volatile solvent; and

a pH adjuster;

wherein the charged hydrogel-forming polymer is selected from poly(ethylene glycol)-grafted cationic hydrogels; a copolymer of 2-hydroxyethyl methacrylate (HEMA) and methacrylamide propyltrimethylammonium chloride; a crosslinked cationic copolymer of vinylpyrrolidone (VP) and 3-dimethylaminopropyl(meth)acrylamide (DMAPMA) monomer; (3-acrylamidopropyl)-trimethylammonium chloride (APTMAC1) monomer crosslinked with a neutral crosslinker N,N-methylenebisacrylamide; crosslinked hydrophobically-modified dialkyldiallylammonium salts; a vinyl ether of monoethanolamine; and copolymerization of N,N,N,N-tetrallylpiperazinium dibromide (TAP) with N,N-diallyl morpholinium bromide (DAM).

8. The multiple-component material of claim 7 , wherein the hydrogel-forming composition comprises a neutral, hydrogel-forming polymer.

9. The multiple-component material of claim 7 , wherein the hydrogel-forming layer is formed on the substrate in one or more patterns selected from stripes, dots, geometric shapes, irregular shapes, alpha-numeric characters, anthropomorphic images, pictorial representation of animals, pictorial representation of inanimate objects, cartoon characters, logos and trademarks.

10. A disposable absorbent article including the multiple-component material of claim 7 .

11. The multiple-component material of claim 7 , wherein the multiple-component material is an outer cover material for a disposable absorbent article.

12. The multiple-component material of claim 7 , wherein the color-changing composition includes more than one charged colorant.

13. The multiple-component material of claim 7 , wherein the substrate is a non-woven material.

14. The multiple-component material of claim 7 , wherein the substrate is a polyolefin film.

15. The multiple-component material of claim 14 , wherein the polyolefin film is selected from a polyethylene film and a polypropylene film.

16. A method of printing on a substrate, comprising the steps of:

providing a substrate to be printed upon; and

applying an ink material onto the substrate, wherein the ink material includes a hydrogel-forming composition comprising a charged hydrogel-forming polymer, the hydrogel-forming composition containing at least one charged species;

a charged colorant;

a pH adjuster; and

a volatile solvent;

wherein the charged hydrogel-forming polymer is selected from poly(ethylene glycol)-grafted cationic hydrogels; a copolymer of 2-hydroxyethyl methacrylate (HEMA) and methacrylamide propyltrimethylammonium chloride; a crosslinked cationic copolymer of vinylpyrrolidone (VP) and 3-dimethylaminopropyl(meth)acrylamide (DMAPMA) monomer; (3-acrylamidopropyl)-trimethylammonium chloride (APTMAC1) monomer crosslinked with a neutral crosslinker N,N-methylenebisacrylamide; crosslinked hydrophobically-modified dialkyldiallylammonium salts; a vinyl ether of monoethanolamine; and copolymerization of N,N,N,N-tetrallyl piperazinium dibromide (TAP) with N,N-diallyl morpholinium bromide (DAM).

17. The method of claim 16 , wherein the ink material is applied at room temperature.

18. The method of claim 16 , wherein the ink material is applied onto the substrate in one or more patterns selected from stripes, dots, geometric shapes, irregular shapes, alpha-numeric characters, anthropomorphic images, pictorial representation of animals, pictorial representation of inanimate objects, cartoon characters, logos and trademarks.