Process for the preparation of moisture-curable, polyether urethanes with terminal cyclic urea/reactive silane groups

Abstract

The present invention relates to a process for preparing a moisture-curable, polyether urethane containing terminal cyclic urea/reactive silane groups by reacting at an NCO:OH equivalent ratio of 1.5:1 to 2.5:1 a) a hydroxyl component containing i) 20 to 100% by weight, based on the weight of component a), of a polyether containing two hydroxyl groups and one or more polyether segments, wherein the polyether segments have a number average molecular weight of at least 3000 and a degree of unsaturation of 0.04 milliequivalents/g, provided that the sum of the number average molecular weights of all of the polyether segments per molecule averages 6000 to 20,000, and ii) 0 to 80% by weight, based on the weight of component a), of a polyether containing one hydroxyl group and one or more polyether segments having a number average molecular weight of 1000 to 15,000, with b) an isocyanate component containing i) 20 to 100% by weight, based on the weight of component b), of a compound containing two isocyanate groups, and ii) 0 to 80% by weight, based on the weight of component b), of a compound containing one isocyanate group, provided that total percentages of a-ii) and b-ii) add up to at least 10, to form an isocyanate-containing reaction product and subsequently reacting this reaction product at an equivalent ratio of isocyanate groups to isocyanate-reactive groups of 0.8:1 to 1.1:1 with c) a compound containing an aspartate group and a reactive silane group to form an intermediate polyether urethane containing terminal non-cyclic urea/reactive silane groups and converting the non-cyclic urea groups to cyclic urea groups by reacting the intermediate polyether urethane in the presence of an acid catalyst and heat.

What is claimed is:  
     
         1 . A process for preparing a moisture-curable, polyether urethane containing terminal cyclic urea/reactive silane groups which comprises reacting at an NCO:OH equivalent ratio of 1.5:1 to 2.5:1 
 a) a hydroxyl component containing 
 i) 20 to 100% by weight, based on the weight of component a), of a polyether containing two hydroxyl groups and one or more polyether segments, wherein the polyether segments have a number average molecular weight of at least 3000 and a degree of unsaturation of 0.04 milliequivalents/g, provided that the sum of the number average molecular weights of all of the polyether segments per molecule averages 6000 to 20,000, and  
 ii) 0 to 80% by weight, based on the weight of component a), of a polyether containing one hydroxyl group and one or more polyether segments having a number average molecular weight of 1000 to 15,000, with  
   b) an isocyanate component containing 
 i) 20 to 100% by weight, based on the weight of component b), of a compound containing two isocyanate groups, and  
 ii) 0 to 80% by weight, based on the weight of component b), of a compound containing one isocyanate group,  
 provided that total percentages of a-ii) and b-ii) add up to at least 10, to form an isocyanate-containing reaction product and subsequently reacting this reaction product at an equivalent ratio of isocyanate groups to isocyanate-reactive groups of 0.8:1 to 1.1:1 with  
   c) a compound containing an isocyanate-reactive group and one reactive silane groups in which at least 10 mole % of component c) is a compound corresponding to the formula                           wherein 
 X represents identical or different organic groups which are inert to isocyanate groups below 100° C., provided that at least two of these groups are alkoxy or acyloxy groups,  
 Y represents a linear or branched alkylene group containing 1 to 8 carbon atoms,  
 R 1  and R 2  are identical or different and represent organic groups which are inert to isocyanate groups at a temperature of 100° C. or less and  
 R 3  and R 4  are identical or different and represent hydrogen or organic groups which are inert towards isocyanate groups at 1 5 a temperature of 100 20  C. or less,  
 to form an intermediate polyether urethane containing at least a portion of terminal non-cyclic urea/reactive silane groups corresponding to formula II  
                     
 and converting the non-cyclic urea groups to cyclic urea groups by reacting the intermediate polyether urethane in the presence of an acid catalyst and heat to form terminal cyclic urea/reactive silane groups corresponding to formula III and/or formula IV  
                     
   
     
     
         2 . The process of  claim 1  wherein at least 50 mole % of component c) is a compound corresponding to formula 1.  
     
     
         3 . The process of  claim 1  wherein at least 80 mole % of component c) is a compound corresponding to formula I and 
 X represents identical or different alkoxy groups having 1 to 4 carbon atoms,  
 Y represents a linear radical containing 2 to 4 carbon atoms or a branched radical containing 5 to 6 carbon atoms and  
 R 1  and R 2  are identical or different and represent alkyl groups having 1 to 4 carbon atoms and  
 R 3  and R 4  represent hydrogen.  
 
     
     
         4 . The process of  claim 1  wherein component a-i) is present in an amount of 20 to 90% by weight, based on the weight of component a); and component a-ii) is present in an amount of 10 to 80% by weight, based on the weight of component a).  
     
     
         5 . The process of  claim 2  wherein component a-i) is present in an amount of 20 to 90% by weight, based on the weight of component a); and component a-ii) is present in an amount of 10 to 80% by weight, based on the weight of component a).  
     
     
         6 . The process of  claim 3  wherein component a-i) is present in an amount of 20 to 90% by weight, based on the weight of component a); and component a-ii) is present in an amount of 10 to 80% by weight, based on the weight of component a).  
     
     
         7 . The process of  claim 1  wherein component b-i) is present in an amount of 20 to 90% by weight, based on the weight of component b); and component b-ii) is present in an amount of 10 to 80% by weight, based on the weight of component b).  
     
     
         8 . The process of  claim 2  wherein component b-i) is present in an amount of 20 to 90% by weight, based on the weight of component b); and component b-ii) is present in an amount of 10 to 80% by weight, based on the weight of component b).  
     
     
         9 . The process of  claim 3  wherein component b-i) is present in an amount of 20 to 90% by weight, based on the weight of component b); and component b-ii) is present in an amount of 10 to 80% by weight, based on the weight of component b).  
     
     
         10 . The process of  claim 1  wherein component a-i) is present in an amount of 30 to 80% by weight, based on the weight of component a); component a-ii) is present in an amount of 20 to 70% by weight, based on the weight of component a).  
     
     
         11 . The process of  claim 2  wherein component a-i) is present in an amount of 30 to 80% by weight, based on the weight of component a); component a-ii) is present in an amount of 20 to 70% by weight, based on the weight of component a).  
     
     
         12 . The process of  claim 3  wherein component a-i) is present in an amount of 30 to 80% by weight, based on the weight of component a); component a-ii) is present in an amount of 20 to 70% by weight, based on the weight of component a).  
     
     
         13 . The process of  claim 1  wherein component b-i) is present in an amount of 30 to 80% by weight, based on the weight of component b); component b-ii) is present in an amount of 20 to 70% by weight, based on the weight of component b).  
     
     
         14 . The process of  claim 2  wherein component b-i) is present in an amount of 30 to 80% by weight, based on the weight of component b); component b-ii) is present in an amount of 20 to 70% by weight, based on the weight of component b).  
     
     
         15 . The process of  claim 3  wherein component b-i) is present in an amount of 30 to 80% by weight, based on the weight of component b); component b-ii) is present in an amount of 20 to 70% by weight, based on the weight of component b).  
     
     
         16 . The process of  claim 1  wherein the polyether segments of component a-i) have a number average molecular weight of at least 6000 and the polyether segments of component a-ii) have a number average molecular weight of 3000 to 12,000.  
     
     
         17 . The process of  claim 2  wherein the polyether segments of component a-i) have a number average molecular weight of at least 6000 and the polyether segments of component a-ii) have a number average molecular weight of 3000 to 12,000.  
     
     
         18 . The process of  claim 3  wherein the polyether segments of component a-i) have a number average molecular weight of at least 6000 and the polyether segments of component a-ii) have a number average molecular weight of 3000 to 12,000.  
     
     
         19 . The process of  claim 4  wherein the polyether segments of component a-i) have a number average molecular weight of at least 6000 and the polyether segments of component a-ii) have a number average molecular weight of 3000 to 12,000.  
     
     
         20 . The process of  claim 10  wherein the polyether segments of component a-i) have a number average molecular weight of at least 6000 and the polyether segments of component a-ii) have a number average molecular weight of 3000 to 12,000.