Curable composition

Abstract

Powder coating compositions comprise a binder selected from carboxyl-group-containing polyesters, carboxyl-group-containing poly(meth)acrylates and mixtures of the said substances, and one or more novel epoxy compounds.

What is claimed is:  
     
         1 . A powder coating composition comprising a binder selected from carboxyl-group-containing polyesters, carboxyl-group-containing poly(meth)acrylates and mixtures of the said substances, and one or more epoxy compounds, wherein the epoxy compounds comprise at least one compound of formula (I) that is solid at 25° C.:  
       
         
           
           
               
               
           
         
       
       wherein 
 A corresponds to a group of formula (II), (III), (IV) or (VI):  
                     
 in which  
 B is an x-valent organic radical that is derived from a polyol having x or more hydroxyl groups by the removal of x hydroxyl groups;  
 E is a (2x)-valent organic radical that is derived from a polyol having (2×) or more hydroxyl groups by the removal of (2×) hydroxyl groups; and  
 D is a (y+2z)-valent radical that is derived from a polyol having (y+2z) or more hydroxyl groups by the removal of (y+2z) hydroxyl groups;  
 R 1  and R 5  are each independently of the other hydrogen, halogen, C 1 -C 4 alkyl or C 1 -C 4 alkoxy or are together a methylene group; and  
 R 2 , R 3 , R 4 ,  
 R 6 , R 7 , R 8    
 and R 9  are each independently of the others hydrogen, halogen, C 1 -C 4 alkyl or C 1 -C 4 alkoxy; and  
 x is an integer of at least 3;  
 y is an integer from 1 to (x−1) and  
 z is (x−y).  
 
     
     
         2 . A powder coating composition according to  claim 1 , wherein A corresponds to a group of formula (II).  
     
     
         3 . A powder coating composition according to  claim 2 , wherein x is from 3 to 6, preferably 4.  
     
     
         4 . A powder coating composition according to  claim 3 , wherein B is a radical that is derived from an aliphatic polyol having from 3 to 20 carbon atoms, a cycloaliphatic polyol having from 5 to 20 carbon atoms or a mixed aliphatic-cycloaliphatic polyol having from 7 to 20 carbon atoms.  
     
     
         5 . A powder coating composition according to  claim 1 , wherein the polyol is 1,3-dihydroxy-2,2-di(hydroxymethyl)propane (pentaerythritol).  
     
     
         6 . A powder coating composition according to  claim 1 , wherein A corresponds to a group of formula (III).  
     
     
         7 . A powder coating composition according to  claim 6 , wherein x is from 3 to 6, preferably 3.  
     
     
         8 . A powder coating composition according to  claim 6 , wherein E is a radical that is derived from an aliphatic polyol having from 3 to 20 carbon atoms.  
     
     
         9 . A powder coating composition according to  claim 8 , wherein the polyol is selected from mannitol, especially D-mannitol, sorbitol, especially D-sorbitol, and dulcitol.  
     
     
         10 . A powder coating composition according to  claim 1 , wherein A corresponds to a group of formula (IV).  
     
     
         11 . A powder coating composition according to  claim 1 , that furthermore comprises at least one epoxy compound of formula (I) that is solid at 25° C. in which 
 A corresponds to a group of formula (II) or (III) and  
 x is2.  
 
     
     
         12 . A powder coating composition according to  claim 11 , wherein the epoxy compounds of formula (I) wherein x is at least 3 and the epoxy compounds of formula (I) wherein x is 2 are present in a molar ratio of up to a maximum of 1:2 preferably of up to a maximum of 1:1.  
     
     
         13 . A powder coating composition according to  claim 1 , which is substantially free of glycidyl compounds, especially TGIC and glycidyl esters.  
     
     
         14 . A process for the preparation of a compound of formula (I) wherein 
 A corresponds to a group of formula (II),    B corresponds to an x-valent organic radical that is derived from a hydroxyl compound having x or more hydroxyl groups, and    x corresponds to an integer of at least 1,    which comprises the transesterification of a cyclohexene-3-carboxylic acid ester with an alcohol of formula B(OH) x , wherein x corresponds to an integer of at least 1, in the presence of LiNH 2 , with continuous removal from the reaction mixture of the alcohol freed from the cyclohexene-3-carboxylic acid ester, the transesterification being followed by the epoxidation of the carbon double bond(s) of the resulting transesterification product.    
     
     
         15 . A process according to  claim 14 , wherein x is at least 3.