Poly(THF)-based polyurethane dispersions

1. An aqueous polyurethane dispersion comprising polyurethanes obtainable from

A1) at least two organic di- or polyisocyanates that are different from one another,

A2) at least two poly(tetramethylene glycol) polyether diols A2a) and A2b) that are different from one another, each with the structure (HO—(CH 2 —CH 2 —CH 2 —CH 2 —O) x —H), wherein the relevant diol precursors are present with number-average molecular weights M n of 400 to 8000 g/mol and the diol with the lower molar mass A2a) has a number-average molecular weight M n which is 10 to 80% of the number-average molecular weight M n of the diol with the higher molar mass A2b),

A3) optionally hydroxy-functional compounds with molecular weights of 62 to 399 g/mol, and

A4) optionally non-ionic hydrophilising agents,

and

one or more amino-functional compounds B),

wherein, based on the total mass of the polyurethane, less than 10 wt. % of diol precursors with number-average molecular weights M n of 400 to 8000 g/mol are contained which do not correspond to A2).

2. The aqueous polyurethane dispersion according to claim 1 , wherein the number-average molecular weight of the polyurethane is in the range between 1000 and 200000 g/mol.

3. The aqueous polyurethane dispersion according to claim 1 , wherein component A2) consists of two poly(tetramethylene glycol) polyether diols A2a) and A2b) that are different from one another, each with the structure (HO—(CH 2 —CH 2 —CH 2 —CH 2 —O) x —H), wherein the relevant diol precursors are present with number-average molecular weights M n of 400 to 8000 g/mol and the diol with the lower molar mass A2a) has a number-average molecular weight M n which is 10 to 80% of the number-average molecular weight M n of the diol with the higher molar mass A2b).

4. The aqueous polyurethane dispersion according to claim 1 , wherein component A1) comprises at least two organic diisocyanates that are different from one another.

5. The aqueous polyurethane dispersion according to claim 1 , wherein component A1) consists of two organic diisocyanates that are different from one another.

6. The aqueous polyurethane dispersion according claim 1 , wherein the polyurethanes contain anionic groups, which are optionally sulfonate groups.

7. A process for the production of an aqueous polyurethane dispersion according to claim 1 , comprising producing an isocyanate-functional prepolymer from

A1) at least two organic di- or polyisocyanates that are different from one another,

A2) at least two poly(tetramethylene glycol) polyether diols A2a) and A2b) that are different from one another, each with the structure (HO—(CH 2 —CH 2 —CH 2 —CH 2 —O) x —H), wherein the relevant diol precursors are present with number-average molecular weights M n of 400 to 8000 g/mol, and the diol with the lower molar mass A2a) has a number-average molecular weight M n which is 10 to 80%, of the number-average molecular weight M n of the diol with the higher molar mass A2b), A3) optionally hydroxy-functional compounds with molecular weights of 62 to 399 g/mol, and

A4) optionally non-ionic hydrophilising agents,

and reacting

C) free NCO groups of said isocyanate-functional prepolymer in full or in part with one or more amino-functional compounds B), optionally comprising primary and/or secondary amines and/or diamines,

wherein the polyurethane thus obtained is dispersed in water before, during or after step B).

8. A composition, comprising an aqueous polyurethane dispersion according to claim 1 , which is capable of being used as a coating composition, adhesive and/or sealant on a fibre-based substrate.

9. An object and/or article comprising a fibre-based substrate which is produced, coated, bonded and/or sealed using an aqueous polyurethane dispersion according to claim 1 .

10. The aqueous polyurethane dispersion according to claim 1 , wherein the number-average molecular weight of the polyurethane is in the range between 5000 and 150000 g/mol.

11. The aqueous polyurethane dispersion according to claim 1 , wherein the relevant diol precursors are present with number-average molecular weights M n of 600 to 3000 g/mol, and wherein the diol with the lower molar mass A2a) has a number-average molecular weight M n which is 30 to 70% of the number-average molecular weight M n of the diol with the higher molar mass A2b).

12. The aqueous polyurethane dispersion according to claim 1 , wherein, based on the total mass of the polyurethane, less than 5 wt. % of diol precursors with number-average molecular weights M n of 400 to 8000 g/mol are contained which do not correspond to A2).

13. The aqueous polyurethane dispersion according to claim 1 , wherein no diol precursors are contained which do not correspond to A2).

14. The aqueous polyurethane dispersion according to claim 1 , wherein A1) is selected from the group consisting of 1,4-butylene diisocyanate, 1,6-hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), 2,2,4- and/or 2,4,4-trimethylhexamethylene diisocyanate, the isomeric bis(4,4′-isocyanatocyclohexyl)methanes or mixtures thereof with any isomer content, 1,4-cyclohexylene diisocyanate, 1,4-phenylene diisocyanate, 2,4- and/or 2,6-toluene diisocyanate, 1,5-naphthylene diisocyanate, 2,2′- and/or 2,4′- and/or 4,4′-diphenylmethane diisocyanate, 1,3- and/or 1,4-bis(2-isocyanatoprop-2-yl)benzene (TMXDI), 1,3-bis(isocyanatomethyl)benzene (XDI) and alkyl-2,6-diisocyanatohexanoate (lysine diisocyanate) with C1-C8 alkyl groups, portions of modified diisocyanates having a functionality of ≥2 with uretdione, isocyanurate, urethane, allophanate, biuret, iminooxadiazinedione or oxadiazinetrione structure, and mixtures thereof.

15. The aqueous polyurethane dispersion according to claim 1 , wherein A1) is selected from the group consisting of hexamethylene diisocyanate, isophorone diisocyanate, isomeric bis(4,4′-isocyanatocyclohexyl)methanes, and mixtures thereof.

16. The aqueous polyurethane dispersion according to claim 1 , wherein component B) is selected from primary or secondary amine and/or diamines.

17. The aqueous polyurethane dispersion according to claim 1 , wherein component B) is a mixture of component B1), amines that have no ionic or ionogenic group, and component B2), amines that have ionic or ionogenic groups, wherein B1) comprises di- or polyamines, primary/secondary amines, or monofunctional, isocyanate-reactive amine compounds, and B2) comprises alkali metal salts of mono- and diaminosulfonic acids.

18. The aqueous polyurethane dispersion according to claim 17 , wherein component B1) is selected from 1,2-ethylene-diamine, 1,2- and 1,3-diaminopropane, 1,4-diaminobutane, 1,6-diaminohexane, isophorone diamine, mixtures of isomers of 2,2,4- and 2,4,4-trimethylhexamethylenediamine, 2-methylpentamethylenediamine, diethylenetriamine, 4,4-diaminodicyclohexylmethane, hydrazine hydrate, dimethylethylenediamine, diethanolamine, 3-amino-1-methylaminopropane, 3-amino-1-ethylaminopropane, 3-amino-1-cyclohexylaminopropane, 3-amino-1-methylaminobutane, N-aminoethylethanolamine, ethanolamine, 3-aminopropanol, neopentanolamine, methylamine, ethylamine, propylamine, butylamine, octylamine, laurylamine, stearylamine, isononyloxypropylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, N-methylaminopropylamine, diethyl(methyl)aminopropylamine, morpholine, piperidine or suitable substituted derivatives thereof, amide amines from diprimary amines and monocarboxylic acids, or N,N-dimethylaminopropylamine;

and component B2) is selected from salts of 2-(2-aminoethylamino)ethanesulfonic acid, ethylenediamine propyl- or -butylsulfonic acid, 1,2- or 1,3-propylenediamine-β-ethylsulfonic acid or taurine.

19. The aqueous polyurethane dispersion according to claim 1 , wherein A3) is present.

20. The aqueous polyurethane dispersion according to claim 1 , wherein A2a) has a number average molecular weight of 400 to 1,500 and A2b) has a number average molecular weight of 1,500 to 8,000.