Dimer fatty acid-containing reaction product and coating composition comprising the reaction product

Abstract

The present invention relates to a reaction product preparable by reacting (a) dimer fatty acids with (b) at least one compound (b) of the general structural formula (I) where R is a C 3 to C 6 alkylene radical and n correspondingly is selected such that the compound (b) possesses a number-average molecular weight of 120 to 445 g/mol, components (a) and (b) are used in a molar ratio of 0.7/2.3 to 1.6/1.7, and the resulting reaction product possesses a number-average molecular weight of 600 to 4000 g/mol and an acid number of less than 10 mg KOH/g. The invention further relates to a pigmented aqueous basecoat material which comprises this reaction product, and to the use of the reaction product in pigmented aqueous basecoat materials for improving adhesion. The present invention further relates to a method for producing multicoat paint systems, and also to the multicoat paint systems producible by means of said method.

1 . A reaction product containing dimer fatty acid and preparable by reacting:
 (a) at least one dimer fatty acid(s) with   (b) at least one compound of the general structural formula (I):   
       
         
           
           
               
               
           
         
         where R is a C 3  to C 6  alkylene radical and n correspondingly is selected such that the compound (b) possesses a number-average molecular weight of 120 to 445 g/mol, components (a) and (b) are used in a molar ratio of 0.7/2.3 to 1.6/1.7, and the resulting reaction product possesses a number-average molecular weight of 600 to 4000 g/mol and an acid number of less than 10 mg KOH/g. 
       
     
     
         2 . The reaction product as claimed in  claim 1 , wherein the dimer fatty acid(s) used consist of at least 90 wt % of dimeric molecules, less than 5 wt % of trimeric molecules, and less than 5 wt % of monomeric molecules and other byproducts. 
     
     
         3 . The reaction product as claimed in  claim 1 , wherein the compound (b) possesses a number-average molecular weight of 140 to 425 g/mol. 
     
     
         4 . The reaction product as claimed in  claim 1 , wherein the group R as per the general structural formula (I) comprises isopropylene radicals or tetramethylene radicals and the compound (b) possesses a number-average molecular weight of 170 to 350 g/mol. 
     
     
         5 . The reaction product as claimed in  claim 1 , wherein components (a) and (b) are used in a molar ratio of 0.9/2.1 to 1.5/1.8. 
     
     
         6 . The reaction product as claimed in  claim 1 , which possesses a number-average molecular weight of 800 to 3500 g/mol. 
     
     
         7 . A pigmented aqueous basecoat material which comprises at least one reaction product as claimed in  claim 1 . 
     
     
         8 . The pigmented aqueous basecoat material as claimed in  claim 7 , wherein the sum total of weight-percentage fractions of the reaction products, based on the total weight of the pigmented aqueous basecoat material(s) is 0.1 to 30 wt %. 
     
     
         9 . The pigmented aqueous basecoat material as claimed in  claim 7 , which comprises as further binder at least one polyurethane resin. 
     
     
         10 . The pigmented aqueous basecoat material as claimed in  claim 7 , which comprises a polyurethane resin that is grafted by means of olefinically unsaturated monomers and that also comprises hydroxyl groups, and a melamine resin. 
     
     
         11 . A method for improving the adhesion of a pigmented basecoat material comprising incorporating the reaction product according to  claim 1  into said pigmented basecoat material. 
     
     
         12 . A method for producing a multiple-coat paint system, where
 (1) applying a pigmented aqueous basecoat material according to  claim 7  to a substrate,   (2) forming a polymer film from the coating material applied in stage (1) thus forming a basecoat film,   (3) applying a clearcoat material to the basecoat film, and subsequently   (4) curing the basecoat film together with the clearcoat.   
     
     
         13 . The method as claimed in  claim 12 , wherein the substrate is a multicoat paint system which possesses defects. 
     
     
         14 . A multicoat paint system producible by the method according to  claim 12 . 
     
     
         15 . A multicoat paint system producible by the method according to  claim 13 .