Aqueous Polyurethane-Polyurea Dispersions
The invention relates to a method for producing aqueous polyurethane-polyurea dispersions, where A) first a polyurethane prepolymer containing NCO groups is produced by reacting A1) polyisocyanates with A2) polymeric polyols and/or polyamines having number-average molecular weights of more than 400 to 8,000 g/mol, A3) possibly low-molecular-weight compounds having number-average molecular weights of 17-400 g/mol selected from the group comprising mono- and polyalcohols, mono- and polyamines, and amino alcohols, A4) isocyanate-reactive, ionically or potentially ionically hydrophilic compounds and/or isocyanate-reactive non-ionically hydrophilic compounds, A5) isocyanate-reactive compounds, which contain at least one C 7 to C 24 alkyl group or C 7 to C 24 alkenyl group, and A6) isocyanate-reactive compounds, which contain at least one polysiloxane group, and B); the NCO groups of the prepolymer that are not yet free are reacted with isocyanate-reactive monoamines, polyamines, hydrazine, and/or hydrazides, dimensioned in such a way that a calculated ratio of the isocyanate-reactive NH groups to the NCO groups of 0.7 to 1.2 is achieved.
1 . A process for preparing aqueous polyurethane-polyurea dispersions which comprises
A) first an NCO-containing polyurethane prepolymer being produced by reaction of
A1) polyisocyanates with
A2) polymeric polyols and/or polyamines having number average molecular weights of more than 400 to 8000 g/mol,
A3) optionally low molecular weight compounds having number average molecular weights of 17-400 g/mol selected from the group consisting of mono- and polyalcohols, mono- and polyamines and amino alcohols,
A4) isocyanate-reactive ionically or potentially ionically hydrophilizing compounds and/or isocyanate-reactive nonionically hydrophilizing compounds,
A5) isocyanate-reactive compounds comprising at least one C 7 - to C 24 -alkyl or C 7 - to C 24 -alkenyl group, and
A6) isocyanate-reactive compounds comprising at least one polysiloxane group, and
B) the still free NCO groups of the prepolymer being reacted with isocyanate-reactive monoamines, polyamines, hydrazine and/or hydrazides sufficient for an arithmetic ratio of the isocyanate-reactive NH groups to the NCO groups in the range from 0.7 to 1.2.
2 . The process according to claim 1 wherein the C 7 - to C 24 -alkyl or C 7 - to C 24 -alkenyl groups introduced via component A5) are present as side chains.
3 . The process according to claim 1 and/or 2 wherein the polysiloxane groups introduced via component A6) are present as side chains.
4 . The process according to one or more of claims 1 - 3 , wherein
C) the prepolymer obtained from step A) is either prepared in aliphatic ketones or esters and/or after the reaction in step A) dissolved/diluted in aliphatic ketones or esters.
5 . The process according to one or more of claims 1 - 4 wherein the A1) components are diisocyanates.
6 . The process according to one or more of claims 1 - 5 wherein the A1) components are aliphatic diisocyanates.
7 . The process according to one or more of claims 1 - 6 wherein the A2) to A6) components consist in molar terms to an extent of more than 95% of compounds having one or two isocyanate-reactive groups, wherein carboxylic acid groups are regarded as isocyanate nonreactive.
8 . The process according to one or more of claims 1 - 7 wherein the NCO-containing polyurethane prepolymer is obtained by reaction of 10% to 45% by weight of component A1), 30% to 80% by weight of component A2), 0% to 10% by weight of component A3), 0.1% to 20% by weight of component A4), 0.1% to 20% by weight of component A5) and 0.1% to 20% by weight of component A6), wherein the sum total of all the components mentioned adds up to 100% by weight.
9 . The process according to one or more of claims 1 - 8 wherein the compounds according to A5) comprise at least one unbranched alkyl or alkenyl chain of 7 to 24 carbons.
10 . The process according to claim 9 wherein the compounds according to A5) comprise at least one unbranched saturated alkyl chain of 11 to 22 carbons.
11 . The process according to claim 10 wherein the compounds according to A5) comprise at least one unbranched saturated alkyl chain of 15 to 20 carbons.
12 . The process according to one or more of claims 1 - 8 wherein the compounds according to A6) comprise at least one structural unit of formula (3)
where n averages from 3 to 55 and R and R′ are hydrocarbyl groups.
13 . The process according to claim 12 wherein n averages from 3 to 25 and R and R′ are alkyl or aryl groups.
14 . The process according to claim 13 wherein n averages from 6 to 20 and R and R′ are methyl or phenyl groups.
15 . An aqueous polyurethane-polyurea dispersion obtainable by the process according to any one of claims 1 to 14 .
16 . The use of an aqueous polyurethane-polyurea dispersion according to claim 15 in the manufacture of coatings.
17 . A coating obtainable from an aqueous polyurethane-polyurea dispersion according to claim 16 .
18 . A substrate coated with a coating according to claim 17 .
19 . A flexible sheetlike substrate coated with a coating according to claim 17 .
20 . The substrate according to claim 19 wherein the substrate is leather or artificial leather.
21 . The substrate according to claim 20 wherein the leather is full grain, buffed or split leather.