Polyurethane latexes, processes for preparing them and polymers prepared therewith

Abstract

Disclosed are stable aqueous polyurethane latexes prepared from prepolymer formulations including a polyisocyanate component and polyol component, wherein from 5 to 40 percent of the weight of the polyol component is ethylene oxide in the form of ethylene oxide applied as an end cap onto a propylene oxide or higher oxyalkylene polyoxyalkylene polyol, and no more than 45 percent of the weight of polyol component is ethylene oxide. These latexes are prepared without the use of organic solvents.

What is claimed is:  
     
         1 . A process for preparing a stable polyurethane latex comprising admixing a polyurethane prepolymer with water, a surfactant, and a chain extender under conditions sufficient to disperse the prepolymer and chain extender reaction product to form a latex wherein: 
 (i) the prepolymer is prepared from a prepolymer formulation including a polyisocyanate component and polyol component,    (ii) from 5 to 40 percent of the weight of the polyol component is ethylene oxide in the form of ethylene oxide applied as an end cap onto a propylene oxide or higher oxyalkylene polyoxyalkylene polyol, and    (iii) no more than 45 percent of the weight of polyol component is ethylene oxide.    
     
     
         2 . The process of  claim 1  wherein the process is performed in two stages: a first stage of admixing a prepolymer with water and a surfactant to form an emulsion, and a second stage of admixing the emulsion with a chain extender.  
     
     
         3 . The process of  claim 1  wherein the chain extender is an amine.  
     
     
         4 . The process of  claim 3  wherein the amine is a diamine.  
     
     
         5 . The process of  claim 1  wherein the surfactant is an ionic surfactant.  
     
     
         6 . The process of  claim 5  wherein the ionic surfactant is an anionic surfactant.  
     
     
         7 . The process of  claim 1  wherein the process is performed with the proviso that no organic solvent is used to prepare the latex.  
     
     
         8 . The process of  claim 1  wherein the chain extender is water.  
     
     
         9 . The process of  claim 8  wherein the process is performed in one step.  
     
     
         10 . The process of  claim 1  wherein the polyol component includes an ethylene oxide capped polyoxypropylene diol having a molecular weight of from about 1500 to about 6000 and a polyether monol having an ethylene oxide content of greater than 40 percent.  
     
     
         11 . The process of  claim 10  wherein the polyol component includes a diol having a molecular weight of from about 30 to about 500.  
     
     
         12 . A stable polyurethane latex prepared by the process of  claim 1 .  
     
     
         13 . A polyurethane polymer coated substrate prepared by a process comprising the steps of: 
 (1) preparing a latex according the process of  claim 1 ,    (2) applying the latex to a substrate, and    (3) dehydrating the latex.    
     
     
         14 . A stable polyurethane latex containing no organic solvents comprising: 
 (1) a continuous aqueous phase; and dispersed therein:    (2) from about 0.1 to about 10.0 percent by weight of an anionic surfactant; and    (3) a polymer comprising the reaction product of: 
 (i) an ethylene oxide capped poly(propylene oxide) polyol component having a molecular weight of from about 1500 to about 6000 wherein from 5 to 40 percent by weight of the polyol component is ethylene oxide,  
 (ii) optionally a polyether monol having an ethylene oxide content of greater than 40% by weight,  
 (iii) optionally, a diol having a molecular weight of from about 30 to 500,  
 (iv) an aromatic polyisocyanate, and  
 (v) a diamine, water, or combination thereof.