Composition, for use in coatings, based on a mixture of emulsion(s) and of dispersion(s) of polyol polymer and coating(s) produced therefrom

Abstract

The present invention relates to a composition comprising at least one masked or unmasked polyisocyanate in the form of an aqueous emulsion whose mean size is between 0.1 and 10 micometers; and at least one polyhydroxylated polymer, advantageously a polyol, in the form of a second aqueous dispersion whose mean size is between 10 and 200 nanometers wherein the content of polyhydroxylated polymer, advantageously of polyol, expressed in mass percent, is at least equal to 5/6R-20, with R equal to the ratio of the mean size (d 50 ) of the emulsion to that of the dispersion of polyhydroxylated polymer, advantageously of polyol.

1 . A composition comprising: 
 at least one masked or unmasked polyisocyanate in the form of an aqueous emulsion whose mean size is between about 0.1 and about 10 micrometers, and    at least one polyhydroxylated polymer, in form of an aqueous dispersion whose mean size is between about 10 and about 200 nanometers wherein the quantity of polyhydroxylated polymer in the mixture, expressed in mass percent, is at least equal to about 5/6R-20 R being equal to the ratio of the mean size (d 50 ) of the emulsion to that of the dispersion of polyhydroxylated polymer.    
     
     
         2 . The composition according to    claim 1    wherein the mean size of the aqueous dispersion is smaller than about 2 and larger than about 0.2 micrometers.  
     
     
         3 . The composition according to    claim 1    wherein the polyhydroxylated polymer is a polyol.  
     
     
         4 . The composition according to    claim 1    wherein the quantity of polyhydroxylated polymer is at least equal to about 5/6R-18.  
     
     
         5 . The composition according to    claim 4    wherein the quantity of polyhydroxylated polymer is at least equal to about 5/6R-16.  
     
     
         6 . The composition according to    claim 1   , wherein said polyisocyanate(s), has(have) a polydispersity index defined as (d 90 −d 10 )/d 50  being at most equal to about 2.  
     
     
         7 . The composition according to    claim 6    wherein the polydispersity index is at most equal to about 1.  
     
     
         8 . The composition according to    claim 1    wherein said polyhydroxylated polymer(s) has(have) a polydispersity index (defined as I=(d 90 −d 10 )/d 50 ) being at most equal to about 2.  
     
     
         9 . The composition according to    claim 8    wherein the polydispersity index is at least equal to about 1.  
     
     
         10 . The composition according to    claim 1    wherein it additionally comprises at least one catalyst of release of the masked isocyanates.  
     
     
         11 . The composition according to    claim 10    wherein the catalyst is a latent tin-based catalyst.  
     
     
         12 . The composition according to    claim 1    wherein the water content of the said compositions is at least equal to about one third of the mass of the composition.  
     
     
         13 . The composition according to    claim 12    wherein the water content is at least about ⅖.  
     
     
         14 . The composition according to    claim 1    wherein said polyisocyanate has(have) one or more isocyanuric rings.  
     
     
         15 . The composition according to    claim 1    wherein said polyisocyanate has(have) one or more biuret functionality.  
     
     
         16 . The composition according to    claim 1    wherein said polyisocyanate is of dimer type.  
     
     
         17 . The composition according to    claim 1    wherein said polyisocyanate is chosen from those in which the nitrogen of at least one of the isocyanate functional groups is attached to a carbon with sp 3  hybridization carrying one or two hydrogen atom(s).  
     
     
         18 . The composition according to    claim 1    wherein said polyisocyanate is masked by a masking agent selected from the group consisting of phenols, ketone oximes and pyrazoles.  
     
     
         19 . The composition according to    claim 18    wherein the masking agent is methyl ethyl ketone oxime.  
     
     
         20 . The composition according to    claim 3    wherein the polyol is a nanolatex.  
     
     
         21 . A process of coating a surface comprising the steps of: 
 (1) coating said surface with the composition of    claim 1   , and    (2) crosslinking said composition.