Preparation of an aromatic bisoxazoline

Abstract

A powder paint binder composition is useful for the preparation of a powder paint composition which includes, as crosslinking agent, an aromatic bisoxazoline obtained by reacting an aromatic carboxylic acid or an ester thereof with an alkanolamine to obtain an hydroxylamide. The hydroxyalkylamide is converted into an aromatic bisoxazoline in the presence of a catalyst. The catalyst includes phosphinic acid, (C 1 -C 26 ) alkyl phosphinic acid, (C 6 -C 20 ) aryl phosphinic acid or an ester or an anhydride derived from one of these acids. Powder paint compositions including the powder paint binder composition form coatings by curing the powder paint. The aromatic bisoxazlines are also useful as chain-extending agents for polymers such as polyamides and polyesters.

What is claimed is:  
     
         1 . A powder paint binder composition comprising a polymer and a crosslinking agent, wherein the crosslinking agent is an aromatic bisoxazoline obtained by reacting an aromatic carboxylic acid or an ester thereof, with an alkalonamine to obtain an hydroxylamide, and converting the hydroxylamide in the presence of a catalyst, to an aromatic bisoxazoline.  
     
     
         2 . A powder paint binder composition according to  claim 1 , wherein the aromatic carboxylic acid or the ester hereof is terephthalic acid, isophthalic acid, di(C 1 -C 4 )alkyl terephthalate and/or di(C 1 -C 4 )alkyl isophthalate.  
     
     
         3 . A powder paint binder composition according to  claim 2 , wherein the aromatic carboxylic acid or the ester is dimethyl terephthalate or dimethyl isophthalate.  
     
     
         4 . A powder paint binder composition according to  claim 1 , wherein the alkanolamine is ethanolamine and/or isopropanolamine.  
     
     
         5 . A powder paint composition comprising a binder composition according to  claim 1 .  
     
     
         6 . A powder coating obtained by curing a powder paint according to  claim 5 .  
     
     
         7 . A polymer composition comprising a polymer and an aromatic bisoxazoline obtained by reacting an aromatic carboxylic acid or an ester thereof, with an alkalonamine to obtain an hydroxylamide, and converting the hydroxylamide in the presence of a catalyst, to an aromatic bisoxazoline.  
     
     
         8 . A polymer composition according to  claim 7 , wherein said polymer comprises polyester, polyacrylate, polyether, polyurethane, polycarbonate, trifluoroethylene copolymer, pentafluoropropylene compolymer, polybutadiene, polystyrene, or styrene-maleic anhydride copolymer.  
     
     
         9 . A method for increasing molecular weight of a polymer which comprises chain-extending the polymer using an aromatic bisoxazoline obtained by reacting an aromatic carboxylic acid or an ester thereof, with an alkalonamine to obtain an hydroxylamide, and converting the hydroxylamide in the presence of a catalyst, to an aromatic bisoxazoline.  
     
     
         10 . A method according to  claim 9 , wherein the polymer is a polyester or a polyamide.