Dimer fatty acid/dimer diol reaction product and use thereof in coating materials

Abstract

The present invention relates to a dimer fatty acid/dimer diol reaction product which is preparable by reacting (a) dimer fatty acids with (b) at least one dimer diol, where components (a) and (b) are used in a molar ratio of 0.7/2.3 to 1.3/1.7 and the resulting dimer fatty acid/dimer diol reaction product possesses a number-average molecular weight of 1200 to 5000 g/mol and an acid number <10 mg KOH/g. The invention further relates to a pigmented aqueous basecoat material which comprises this dimer fatty acid/dimer diol reaction product, and also to the use of said dimer fatty acid/dimer diol reaction product in pigmented aqueous basecoat materials. It relates, further, to a method for producing multicoat paint systems, and also to the multicoat paint systems producible by means of said method. The present invention relates, furthermore, to the refinishing of defects on multicoat paint systems.

1 . A dimer fatty acid/dimer diol reaction product obtained by reacting
 (a) dimer fatty acids with   (b) a dimer diol,   where components (a) and (b) are reacted in a molar ratio of 0.7/2.3 to 1.3/1.7 and the resulting dimer fatty acid/dimer diol reaction product possesses a number-average molecular weight of 1200 to 5000 g/mol and an acid number <10 mg KOH/g.   
     
     
         2 . The dimer fatty acid/dimer diol reaction product of  claim 1 , wherein the dimer fatty acids and/or the dimer diols 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 of other byproducts and/or possess a hydroxyl functionality of 1.8 to 2.2. 
     
     
         3 . The dimer fatty acid/dimer diol reaction product of  claim 1 , wherein the dimer fatty acids are prepared from linolenic, linoleic and/or oleic acid and consist of ≧98 wt % of dimeric molecules, ≦1.5 wt % of trimeric molecules, and ≦0.5 wt % of monomeric molecules and of other byproducts. 
     
     
         4 . The dimer fatty acid/dimer diol reaction product  claim 1 , wherein the dimer diol is prepared by (a) oligomerization of unsaturated fatty acids or esters thereof and subsequent hydrogenation of the acid or ester groups or (b) by oligomerization of unsaturated fatty alcohols having 12 to 22 carbon atoms. 
     
     
         5 . The dimer fatty acid/dimer diol reaction product of  claim 1 , wherein components (a) and (b) are reacted in a molar ratio of 0.9/2.1 to 1.1/1.9. 
     
     
         6 . The dimer fatty acid/dimer diol reaction product as of  claim 1 , having a number-average molecular weight of 1200 to 4000 g/mol. 
     
     
         7 . The dimer fatty acid/dimer diol reaction product of  claim 1 , having an acid number of <5 mg KOH/g. 
     
     
         8 . A pigmented aqueous basecoat material which comprises a dimer fatty acid/dimer diol reaction product of  claim 1 . 
     
     
         9 . The pigmented aqueous basecoat of  claim 8 , wherein the sum total of the weight-percentage fractions of all dimer fatty acid/dimer diol reaction products, based on the total weight of the pigmented aqueous basecoat material, is from 0.1 to 30 wt %. 
     
     
         10 . The pigmented aqueous basecoat material of  claim 8 , which comprises as further binder a polyurethane resin. 
     
     
         11 . The dimer fatty acid/dimer diol reaction product of  claim 1 , wherein the reaction product is suitable in pigmented aqueous basecoat materials adapted for improving adhesion. 
     
     
         12 . A method for producing a multiple-coat paint system, the method comprising:
 (1) applying a pigmented aqueous basecoat material according to  claim 8  to a substrate;   (2) forming a polymer film from the coating material applied in (1);   (3) applying a clearcoat material to the resulting basecoat film; and subsequently   curing the basecoat film together with the clearcoat film.   
     
     
         13 . The method of  claim 12 , wherein the substrate from the applying (1) is a multicoat paint system which has defects. 
     
     
         14 . A multicoat paint system obtained by the method of  claim 12 . 
     
     
         15 . (canceled)