Aqueous Polyurethane-Polyurea Dispersions

Abstract

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.

What is claimed is: 
     
         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.