Allophonate modified polyisocyanates

Abstract

A composition that includes isocyanate group containing compounds that include on average i) a NCO functionality less than or equal to 3.5; and ii) from 1.5 to 8 percent by weight, based on the isocyanate containing compound, of allophanate groups; and which is substantially free of uretdione groups. The composition can be used in two component elastomeric coating compositions that include a component A the above-described composition and a component B that includes a compound containing one or more functional groups that are reactive with isocyanate groups. The elastomeric coating compositions can be used to coat substrates.

1 . A composition comprising isocyanate group-containing compounds that include on average 
 i) a NCO functionality less than or equal to 3.5; and    ii) from 1.5 to 8 percent by weight, based on the isocyanate containing compound, of allophanate groups; and    which is substantially free of uretdione groups,    wherein the isocyanate group-containing compounds are the reaction products of an isocyanate and a combination of saturated alcohols, and contain one or more structural units conforming to the following formula                          wherein    R 1  is selected from the group consisting of a divalent aliphatic hydrocarbon group having from 4 to 18 carbon atoms, a divalent cycloaliphatic hydrocarbon group having from 5 to 15 carbon atoms, and a divalent araliphatic hydrocarbon group having from 7 to 15 carbon atoms, wherein R 1  can optionally include from 1 to 3 NCO groups;    R 2  is selected from the group consisting of a divalent aliphatic hydrocarbon group having from 4 to 18 carbon atoms, a divalent cycloaliphatic hydrocarbon group having from 5 to 15 carbon atoms, and a divalent araliphatic hydrocarbon group having from 7 to 15 carbon atoms, wherein R 2  can optionally include from 1 to 3 NCO groups; and    R 3  is selected from the group consisting of a C 1  to C 32  linear, branched or cyclic aliphatic, cycloaliphatic, araliphatic, or aromatic hydrocarbon group, a —CH3 terminated polyether, a polyester, and a polyurethane.    
   
   
       2 . (canceled)  
   
   
       3 . The composition according to  claim 1  having a bulk viscosity of less than or equal to 750 cps at 25° C.  
   
   
       4 . The composition according to  claim 21  wherein R 1  is a divalent aliphatic hydrocarbon group having from 4 to 12 carbon atoms, R 2  is a divalent aliphatic hydrocarbon group having from 4 to 12 carbon atoms, and R 3  is a C 1 -C 12  linear or branched aliphatic hydrocarbon.  
   
   
       5 . (canceled)  
   
   
       6 . The composition according to  claim 1 , wherein the NCO content of the isocyanate group containing compounds is 8-25 weight percent, based on the weight of the isocyanate group-containing compounds.  
   
   
       7 . A two component elastomeric coating composition that includes a component A comprising isocyanate group containing compounds containing on average 
 i) a mean NCO functionality less than or equal to 3.5; and    ii) from 1.5 to 8 percent by weight, based on the isocyanate containing compound, of allophanate groups; and    which is substantially free of uretdione groups; and    a component B comprising a compound containing one or more functional groups that are reactive with isocyanate groups.    
   
   
       8 . The composition according to  claim 7 , wherein the isocyanate group containing compounds of component A contain one or more structural units conforming to the following formula  
     
       
         
         
             
             
         
       
       wherein  
       R 1  is selected from the group consisting of a divalent aliphatic hydrocarbon group having from 4 to 18 carbon atoms, a divalent cycloaliphatic hydrocarbon group having from 5 to 15 carbon atoms, a divalent araliphatic hydrocarbon group having from 7 to 15 carbon atoms, and a divalent aromatic hydrocarbon group having 6 to 15 carbon atoms, wherein R 1  can optionally include from 1 to 3 NCO groups;  
       R 2  is selected from the group consisting of a divalent aliphatic hydrocarbon group having from 4 to 18 carbon atoms, a divalent cycloaliphatic hydrocarbon group having from 5 to 15 carbon atoms, a divalent araliphatic hydrocarbon group having from 7 to 15 carbon atoms, and a divalent aromatic hydrocarbon group having 6 to 15 carbon atoms, wherein R 2  can optionally include from 1 to 3 NCO groups; and  
       R 3  is selected from the group consisting of a C 2  to C 32  linear, branched or cyclic aliphatic, cycloaliphatic, araliphatic, or aromatic hydrocarbon group, a —CH3 terminated polyether, a polyester, and a polyurethane.  
     
   
   
       9 . The composition according to  claim 7 , wherein the isocyanate group containing compounds of component A have a bulk viscosity of less than or equal to 750 cps at 25° C.  
   
   
       10 . The composition according to  claim 8 , wherein R 1  is a divalent aliphatic hydrocarbon group having from 4 to 12 carbon atoms, R 2  is a divalent aliphatic hydrocarbon group having from 4 to 12 carbon atoms, and R 3  is a C 1 -C 12  linear or branched aliphatic hydrocarbon.  
   
   
       11 . The composition according to  claim 7 , wherein at least some of the isocyanate group containing compounds of component A contain at least two allophanate groups per molecule.  
   
   
       12 . The composition according to  claim 7 , wherein the compound containing one or more functional groups that are reactive with isocyanate groups of component B is selected from the group consisting of polyetherpolyols, polyesterpolyols, hydroxy functional polyurethanes, glycols, glycerine, polyetheramines, polyamines, amine functional polyurethanes, and combinations thereof.  
   
   
       13 . The composition according to  claim 7 , wherein the NCO content of the isocyanate group containing compounds is 8-25 weight percent, based on the weight of the isocyanate group containing compounds.  
   
   
       14 . A process for coating a substrate comprising: 
 a) providing a surface of a substrate;    b) contacting the surface with an elastomeric composition comprising: a component A comprising isocyanate group containing compounds containing on average    i) a mean NCO functionality less than or equal to 3.5; and    ii) from 1.5 to 8 percent by weight, based on the isocyanate containing compound, of allophanate groups; and    which is substantially free of uretdione groups; and    a component B comprising a compound containing one or more functional groups that are reactive with isocyanate groups.    
   
   
       15 . The process according to  claim 14 , wherein the isocyanate group containing compounds of component A contain one or more structural units conforming to the following formula  
     
       
         
         
             
             
         
       
       wherein  
       R 1  is selected from the group consisting of a divalent aliphatic hydrocarbon group having from 4 to 18 carbon atoms, a divalent cycloaliphatic hydrocarbon group having from 5 to 15 carbon atoms, a divalent araliphatic hydrocarbon group having from 7 to 15 carbon atoms, and a divalent aromatic hydrocarbon group having 6 to 15 carbon atoms, wherein R 1  can optionally include from 1 to 3 NCO groups;  
       R 2  is selected from the group consisting of a divalent aliphatic hydrocarbon group having from 4 to 18 carbon atoms, a divalent cycloaliphatic hydrocarbon group having from 5 to 15 carbon atoms, a divalent araliphatic hydrocarbon group having from 7 to 15 carbon atoms, and a divalent aromatic hydrocarbon group having 6 to 15 carbon atoms, wherein R 2  can optionally include from 1 to 3 NCO groups; and  
       R 3  is selected from the group consisting of a C 2  to C 32  linear, branched or cyclic aliphatic, cycloaliphatic, araliphatic, or aromatic hydrocarbon group, a —CH3 terminated polyether, a polyester, and a polyurethane.  
     
   
   
       16 . The process according to  claim 14 , wherein the isocyanate group containing compounds of component A have a bulk viscosity of less than or equal to 750 cps at 25° C.  
   
   
       17 . The process according to  claim 15 , wherein R 1  is a divalent aliphatic hydrocarbon group having from 4 to 12 carbon atoms, R 2  is a divalent aliphatic hydrocarbon group having from 4 to 12 carbon atoms, and R 3  is a C 1 -C 12  linear or branched aliphatic hydrocarbon.  
   
   
       18 . The process according to  claim 14 , wherein at least some of the isocyanate group containing compounds of component A contain at least two allophanate groups per molecule.  
   
   
       19 . The process according to  claim 14  wherein the compound containing one or more functional groups that are reactive with isocyanate groups of component B is selected from the group consisting of polyetherpolyols, polyesterpolyols, hydroxy functional polyurethanes, glycols, glycerine, polyetheramines, polyamines, amine functional polyurethanes, and combinations thereof.  
   
   
       20 . The process according to  claim 14 , wherein the compound containing one or more functional groups that are reactive with isocyanate groups of component B is an aliphatic primary amine optionally also including an aliphatic secondary amine.  
   
   
       21 . The process according to  claim 14 , wherein the substrate comprises one or more materials selected from the group consisting of wood, metals, plastic, paper, ceramics, minerals, stone, glass, and concrete.  
   
   
       22 . The process according to  claim 14 , wherein the substrate is a surface of an automotive vehicle.  
   
   
       23 . The process according to  claim 14 , wherein component A is present in the composition from about 30% to about 70% by volume.  
   
   
       24 . The process according to  claim 14 , wherein component A is at least 90% aliphatic by weight.  
   
   
       25 . The process according to  claim 14 , wherein component A is maintained separate from component B until a time that is less than 6 hours prior to contacting the composition with the substrate.  
   
   
       26 . The process according to  claim 14 , wherein the composition is contacted with the substrate using an apparatus having a first metering container for receiving component A, a second metering container for receiving component B, and a nozzle in fluid communication with the first and second containers for spraying the composition.  
   
   
       27 . The process according to  claim 14 , wherein the composition, in either or both of component A and component B, comprise one or more additives selected from the group consisting of levelling agents, wetting agents, flow control agents, antiskinning agents, antifoaming agents, fillers, viscosity regulators, thixotropic agents, plasticizers, pigments, dyes, UV absorbers, stabilizers, catalysts, and combinations thereof.  
   
   
       28 . The process according to  claim 14 , wherein the NCO content of the isocyanate group containing compounds is 8-25 weight percent, based on the weight of the isocyanate group containing compounds.