Additives for powder coatings

Abstract

A method of use of copolymers containing fluoro groups and hydroxyl groups as additives in powder coating materials, comprising mixing these component with powder coatings resins, the copolymers comprising units of the following monomers: olefinically unsaturated monomers having from 5 to 40 carbon atoms, at least one hydroxyl group, and at least one free-radically polymerizable C═C double bond, alkyl esters of monoolefinically unsaturated monocarboxylic acids or dialkyl esters of olefinically unsaturated dicarboxylic acids or mixtures thereof, and (per)fluoroalkyl esters of said carboxylic acids, and powder coating materials which comprise these additives for the purpose of improving the flow properties and the surface

What is claimed is:  
     
         1 . A method of use of copolymers containing fluoro groups and hydroxyl groups as additives in powder coating materials, comprising mixing these copolymers with powder coating resins, wherein copolymers are used which comprise units of the following monomers: 
 a) olefinically unsaturated monomers having from 5 to 40 carbon atoms, with at least one hydroxyl group and at least one free-radically polymerizable C═C double bond,    b) alkyl esters of monoolefinically unsaturated monocarboxylic acids or dialkyl esters of olefinically unsaturated dicarboxylic acids or mixtures thereof, the alkyl radicals having from 1 to 18 carbon atoms and the carboxylic acids from 3 to 12 carbon atoms,    c) (per)fluoroalkyl esters of the carboxylic acids stated under b, the (per)fluoroalkyl group having from 2 to 20 carbon atoms.    
     
     
         2 . The method of  claim 1 , wherein copolymers are used which contain the stated monomer units in the following mass fractions in the polymer: 
 a: from5 to50%;    b: from 35 to 94.8%;    c: from 0.2 to 15%,    the sum of the mass fractions always necessarily being 100%.    
     
     
         3 . The method of  claim 1 , wherein the copolymers used further include units derived from 
 d) olefinically unsaturated copolymerizable monomers which are free from hydroxyl groups, acid groups, amide groups, and fluorine groups, and which do not belong to group b.    
     
     
         4 . The method of  claim 1  or  3 , wherein the copolymers used further include units derived from 
 e) the olefinically unsaturated carboxylic acids stated under b and/or the monoalkyl esters of the olefinically unsaturated dicarboxylic acids stated under b with C 1  to C 20  alkyl radicals.  
 
     
     
         5 . The method of  claim 3 , wherein the units derived from the monomers d are present in the copolymer in a mass fraction of from 0.2 to 15%.  
     
     
         6 . The use as claimed in  claim 4 , wherein the units derived from the monomers e are present in the copolymer in a mass fraction of from 0.2 to 15%.  
     
     
         7 . The method of  claim 1 , wherein the monomers a are hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxypropyl acrylate and/or 1-hydroxypropyl-2-acrylate.  
     
     
         8 . The method of  claim 1 , wherein the monomers b are methyl methacrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, dimethyl maleate and/or 2-ethylhexyl (meth)acrylate.  
     
     
         9 . The method of  claim 1 , wherein the monomers c are trifluoroethyl (meth)acrylate, hexa fluoroisopropyl (meth)acrylate, heptafluorobutyl (meth)acrylate and/or perfluorooctyl (meth) acrylate.  
     
     
         10 . The use as claimed in  claim 1 , wherein the copolymers are present in the finished powder coating material in a mass fraction of from 0.1 to 3%.  
     
     
         11 . The method of  claim 1 , wherein the copolymers are homogenized in the melt with resins which are solid at room temperature (20° C.) to give a concentrate which, after cooling, is comminuted, the mass fraction of the copolymer in the mixture of resin and copolymer being between 2 and 30%.  
     
     
         12 . The method of  claim 1 , wherein the copolymers are coated in liquid form (as a melt or solution) onto finely divided silicon dioxide (silica) and the resultant powder is mixed into the powder coating formulation.  
     
     
         13 . A powder coating material comprising copolymers containing units of the following monomers: 
 a) olefinically unsaturated monomers having from 5 to 40 carbon atoms, with at least one hydroxyl group and at least one free-radically polymerizable C═C double bond,    b) alkyl esters of monoolefinically unsaturated monocarboxylic acids or dialkyl esters of olefinically unsaturated dicarboxylic acids or mixtures thereof, the alkyl radicals having from 1 to 18 carbon atoms and the carboxylic acids from 3 to 12 carbon atoms,    c) (per)fluoroalkyl esters of the carboxylic acids stated under b, the (per)fluoroalkyl group having from 2 to 20 carbon atoms.