Aqueous polyurethane-urea dispersion

1 . An aqueous polyurethane-urea dispersion comprising polyurethane-urea, wherein the polyurethane-urea is obtained by the reaction of a system comprising the following components:

a. at least a polyisocyanate;

b. at least a polycarbonate polyol with a hydroxyl functionality of 1.9-2.1;

c. at least a polyester polyol with a hydroxyl functionality of 1.9-2.1, said polyester polyol being obtained by the reaction of a mixture comprising at least one of aromatic dibasic acids and aromatic acid anhydrides and a dihydric alcohol;

d. at least an amino-containing compound, which is one or more of amino-containing carboxylic acids, amino-containing carboxylate salts, amino-containing sulfonic acids, and amino-containing sulfonate salts;

e. at least a hydroxyl-containing carboxylic acid;

f. at least a neutralizer; and

g. optionally a compound reactive toward isocyanate groups, which is different from component b)-component e) and has a molecular weight of 32 g/mol-400 g/mol; and

wherein the weight ratio of the polycarbonate polyol to the polyester polyol is 6:1-20:1.

2 . The aqueous polyurethane-urea dispersion according to claim 1 , wherein an amount of organic solvent in the aqueous polyurethane-urea dispersion is less than 1% by weight, relative to the total weight of the aqueous polyurethane-urea dispersion.

3 . The aqueous polyurethane-urea dispersion according to claim 1 , wherein the aqueous polyurethane-urea dispersion has at least one of the following characteristics:

viscosity of 10 mPa·s-1000 mPa·s, tested with a viscometer from Brookfield according to the standard ISO 3219:1994;

solid content of 30%-40% by weight, tested with a halogen moisture analyzer from Mettler Toledo;

Z-average particle size of 30 nm-75 nm, tested with Zetasizer Nano from Malvern; and

polydispersity index of 0-0.3, tested with Zetasizer Nano from Malvern.

4 . The aqueous polyurethane-urea dispersion according to claim 1 , wherein the polyisocyanate is one or more of hexamethylene diisocyanate and isophorone diisocyanate.

5 . The aqueous polyurethane-urea dispersion according to claim 1 , wherein the polycarbonate polyol is one or more of hexanediol polycarbonate, butanediol polycarbonate, neopentyl glycol polycarbonate, 3-methylpentanediol polycarbonate, and copolymers of the above polycarbonates.

6 . The aqueous polyurethane-urea dispersion according to claim 1 , wherein the polyester polyol is one or more of polyhexylene phthalate, polybutylene phthalate, polyneopentyl glycol phthalate, poly(diethylene glycol) phthalate, poly(3-methylpentanediol) phthalate, polyhexylene isophthalate, polybutylene isophthalate, polyneopentyl glycol isophthalate, poly(diethylene glycol) isophthalate, poly(3-methylpentanediol) isophthalate, polyhexylene terephthalate, polybutylene terephthalate, polyneopentyl glycol terephthalate, poly(diethylene glycol) terephthalate and poly(3-methylpentanediol) terephthalate; most preferably one or more of polyhexylene phthalate, polybutylene phthalate, polyneopentyl glycol phthalate, poly(diethylene glycol) phthalate, and poly(3-methylpentanediol) phthalate.

7 . The aqueous polyurethane-urea dispersion according to claim 1 , wherein the amino-containing compound is one or more of 6-aminocaproate, lysinate, N-(2-aminoethyl)-β-alanine monosodium salt, sodium 2-[(2-aminoethyl)amino]ethanesulfonate and sodium 3-(cyclohexylamine)-1-propanesulfonate.

8 . The aqueous polyurethane-urea dispersion according to claim 1 , wherein the hydroxyl-containing carboxylic acid is one or more of 2,2-dimethylolpropionic acid and 2,2-dimethylolbutanoic acid.

9 . A method for preparing the aqueous polyurethane-urea dispersion comprising polyurethane-urea according to claim 1 , comprising the following steps:

i. reacting some or all of component a) at least the polyisocyanate, component b) at least the polycarbonate polyol with a hydroxyl functionality of 1.9-2.1, component c) at least the polyester polyol with a hydroxyl functionality of 1.9-2.1, component e) at least the hydroxyl-containing carboxylic acid and component g) optionally the compound toward isocyanate groups, which is different from component b)-component e), to obtain a prepolymer;

ii. reacting the prepolymer, component d) at least the amino-containing compound and component g) optionally the compound reactive toward isocyanate groups, which is different from component b)-component e), to obtain the polyurethane-urea;

iii. adding component f) at least the neutralizer before or after step ii; and

iv. introducing water before, during or after step ii to obtain the aqueous polyurethane-urea dispersion.

10 . The method according to claim 9 , further comprising step v, introducing an organic solvent miscible with water but inert to isocyanate groups during or after step i, and removing the organic solvent from the aqueous polyurethane-urea dispersion.

11 . A coating composition, a binder or an ink, comprising the aqueous polyurethane-urea dispersion comprising polyurethane-urea according to claim 1 .

12 . A method for preparing coated products, bonded products or printed products comprising providing the aqueous polyurethane-urea dispersion comprising polyurethane-urea according to claim 1 .

13 . An object or an article comprising a substrate, which is prepared, coated, bonded, sealed, or printed with the aqueous polyurethane-urea dispersion comprising polyurethane-urea according to claim 1 .

14 . A printing method comprising the following steps: applying the aqueous polyurethane-urea dispersion comprising polyurethane-urea according to claim 1 onto a surface of a substrate, and then curing.

15 . A printed product comprising a substrate and a coating formed by applying the aqueous polyurethane-urea dispersion comprising polyurethane-urea according to claim 1 onto the substrate.