Non-hazardous water-based polyurethane dispersion

Abstract

A water-based polyurethane dispersion including a chain-extended polyurethane, characterized in that the polyurethane dispersion includes 2,5,7,10-tetraoxaundecane. The water-based polyurethane dispersion is suitable as a non-hazardous water-based coating composition for coatings with a particularly good adhesion on plastic or rubber substrates. The solvent 2,5,7,10-tetraoxaundecane contained therein imparts good film coalescing, good adhesive properties and high strength of the polyurethane dispersion.

1 . A water-based polyurethane dispersion comprising a chain-extended polyurethane, wherein the polyurethane dispersion comprises 2,5,7,10-tetraoxaundecane. 
     
     
         2 . The water-based polyurethane dispersion according to  claim 1 , wherein the chain-extended polyurethane has ionic groups or contains polyethylene oxide units. 
     
     
         3 . The water-based polyurethane dispersion according to  claim 1 , comprising 3 to 60% by weight of 2,5,7,10-tetraoxaundecane based on the total weight of the chain-extended polyurethane in the water-based polyurethane dispersion. 
     
     
         4 . The water-based polyurethane dispersion according to  claim 1 , comprising 45 to 80% by weight of water. 
     
     
         5 . The water-based polyurethane dispersion according to  claim 1 , wherein the chain-extended polyurethane is a reaction product of an isocyanate-terminated polyurethane prepolymer and at least one polyamine as chain extender. 
     
     
         6 . The water-based polyurethane dispersion according to  claim 5 , wherein the isocyanate-terminated polyurethane prepolymer is a reaction product of
 at least one first polyol,   at least one second polyol, which is different from the first polyol, and   at least one diisocyanate,   wherein the at least one second polyol is selected from a polyether polyol having ethylene oxide units, a polyol having an acid group and a polyol having an amine group.   
     
     
         7 . The water-based polyurethane dispersion according to  claim 1 , wherein the water-based polyurethane dispersion is an anionic or non-ionic polyurethane dispersion. 
     
     
         8 . A process for producing the water-based polyurethane dispersion according to  claim 1 , comprising the steps of
 a) reacting at least one first polyol, at least one second polyol and at least one diisocyanate in the presence of 2,5,7,10-tetraoxaundecane and optionally a catalyst to form an isocyanate-terminated polyurethane prepolymer,   b) optionally at least partly neutralizing the isocyanate-terminated polyurethane prepolymer to obtain a neutralized isocyanate-terminated polyurethane prepolymer, and   c) dispersing the optionally neutralized prepolymer in water and adding a chain extender to obtain the water-based polyurethane dispersion comprising the chain-extended polyurethane and 2,5,7,10-tetraoxaundecane.   
     
     
         9 . The process according to  claim 8 , wherein the at least one second polyol has carboxyl groups and/or the at least one diisocyanate is an aliphatic diisocyanate. 
     
     
         10 . The process according to  claim 9 , wherein the base to neutralize the carboxyl groups is a tertiary amine. 
     
     
         11 . The water-based polyurethane dispersion according to  claim 1 , obtainable by a process for producing the water-based polyurethane dispersion, comprising the steps of
 a) reacting at least one first polyol, at least one second polyol and at least one diisocyanate in the presence of 2,5,7,10-tetraoxaundecane and optionally a catalyst to form an isocyanate-terminated polyurethane prepolymer,   b) optionally at least partly neutralizing the isocyanate-terminated polyurethane prepolymer to obtain a neutralized isocyanate-terminated polyurethane prepolymer, and   c) dispersing the optionally neutralized prepolymer in water and adding a chain extender to obtain the water-based polyurethane dispersion comprising the chain-extended polyurethane and 2,5,7,10-tetraoxaundecane.   
     
     
         12 . Coating composition comprising the water-based polyurethane dispersion according to  claim 1  at least one further ingredient selected from other polymer dispersions, fillers, pigments, other solvents, stabilizers, defoamers, surfactants, rheological additives, thickening agents and antioxidants. 
     
     
         13 . A method comprising applying the coating composition according to  claim 12  or of the water-based polyurethane dispersion comprising a chain-extended polyurethane, wherein the polyurethane dispersion comprises 2,5,7,10-tetraoxaundecane, for coating a plastic substrate or a rubber substrate. 
     
     
         14 . A process for coating a plastic substrate or a rubber substrate, comprising applying the coating composition according to  claim 12  or the water-based polyurethane dispersion comprising a chain-extended polyurethane, wherein the polyurethane dispersion comprises 2,5,7,10-tetraoxaundecane, on the substrate and hardening the applied coating. 
     
     
         15 . Coated article obtained by the process according to  claim 14 . 
     
     
         16 . A method comprising applying 2,5,7,10-tetraoxaundecane as coalescent for water-based polyurethane dispersions.