Non-aqueous crosslinkable composition

Abstract

The present invention relates to a crosslinkable composition comprising a polyol, a polyisocyanate crosslinker, a catalyst for catalysing the reaction between —OH groups of said polyol and —NCO groups of said crosslinker, a tertiary acid of formula RR′R″CCOOH (I), wherein each R, R′ and R″ group, independently, is an alkyl, alkenyl, aryl or aralkyl group containing at least one carbon atom, with the proviso that two or three of the R, R′ and R″ groups can be linked to form a ring structure and wherein the R, R′ and/or R″ groups can be substituted, and optionally, a complexing agent containing at least one —SH group, as well as its use for making coatings having improved application properties.

1 . A crosslinkable composition comprising
 a) a polyol having free —OH groups,   b) a polyisocyanate crosslinker having free —NCO groups,   c) a catalyst for catalysing the reaction between —OH groups of said polyol a) and —NCO groups of said crosslinker b),   d) a tertiary acid of formula RR′R″CCOOH (I), wherein each R, R′ and R″ group, independently, is an alkyl, alkenyl, aryl or aralkyl group containing at least one carbon atom, with the proviso that two or three of the R, R′ and R″ groups can be linked to form a ring structure and wherein the R, R′ and/or R″ groups can be substituted, and wherein the total number of carbon atoms in the R, R′ and R″ groups is the range of from 3 to 40, and   e) optionally, a complexing agent containing at least one —SH group.   
     
     
         2 . The crosslinkable composition according to  claim 1 , wherein the complexing agent e) is present and is selected from organic compounds. 
     
     
         3 . The crosslinking composition according to  claim 2 , wherein the complexing agent e) is selected from those of formula R—SH (II), wherein R can be an alkyl, alkenyl, aryl or aralkyl group, optionally substituted with one or more other functional groups such as for example hydroxyl groups, primary, secondary or tertiary amine groups, silane or siloxane groups, ether groups, ester groups, carboxylic acid groups; those of formula HS—(CH 2 ) x —SH (IV) wherein x is from 1 to 20; those of formula (HSCH 2 ) 4-m C(CH 2 SCH 2 CH 2 SH) m  (V) wherein m is from 1 to 4; those which are the reaction products of carboxylic acids of formula HS(CH 2 ) n COOH (VI) wherein n is from 1 to 20 and a polyol having an OH-functionality of 2 or more; as well as mixtures thereof. 
     
     
         4 . The crosslinkable composition according to  claim 1 , wherein the catalyst c) comprises a metal based catalyst, preferably a metal based catalyst wherein the metal selected from tin, bismuth, zinc, zirconium or aluminium, or mixtures thereof. 
     
     
         5 . The crosslinkable composition according to  claim 4 , wherein the catalyst c) is selected from tin(II) carboxylates, dialkyl tin (IV) carboxylates, bismuth carboxylates, zinc carboxylates or aluminium carboxylates or mixtures thereof, preferably dialkyl tin dicarboxylates, bismuth carboxylates or zinc carboxylates, more preferably dibutyl tin dilaurate, dioctyl tin dilaurate or zinc 2-ethylhexanoate. 
     
     
         6 . The crosslinkable composition according to  claim 1 , wherein the amount of complexing agent e) is such that the molar equivalent of —SH groups per molar equivalent of metal from the metal based catalyst c) is in the range of 1-20 molar equivalents of SH per equivalent of metal. 
     
     
         7 . The crosslinkable composition according to  claim 1 , wherein the tertiary acid d) has the general formula RR′R″CCOOH (I) wherein the total number of carbon atoms in the R, R′ and R″ groups is the range of from 3 to 30. 
     
     
         8 . The crosslinkable composition according to  claim 7 , wherein the tertiary acid d) has a general formula RR′R″CCOOH (I) wherein R is a methyl or ethyl group and where the total number of carbon atoms of groups R′ and R″ is from 2 to 17 and where R′ and/or R″ is non-substituted or substituted with only one hydroxyl group. 
     
     
         9 . The crosslinkable composition according to  claim 7 , wherein the tertiary acid d) is selected from the group consisting of neodecanoic acid, versatic acid, 3-hydroxy-2,2-dimethylpropionic acid, 2,2-bis(hydroxymethyl)propionic acid, abietic acid, 1-methyl cyclohexanoic acid, dimethylmalonic acid, ethylmethylmalonic acid, diethylmalonic acid, 2,2-dimethylsuccinic acid, 2,2-diethylsuccinic acid, 2,2-dimethylglutaric acid, 2,2-dimethylpropionic acid, 2,2-dimethylbutyric acid, 2-ethyl-2-methylbutyric acid, 2,2-diethylbutyric acid, 2,2-dimethylvaleric acid, 2-ethyl-2-methylvaleric acid, 2,2-diethylvaleric acid, 2,2-dimethylhexanoic acid, 2,2-diethylhexanoic acid, 2,2-dimethyloctanoic acid, 2-ethyl-2,5-dimethylhexanoic acid, 3-methylisocitric acid, 4,4-dimethylaconitic acid, 1-methylcyclopentane carboxylic acid, 1,2,2-trimethyl-1,3-cyclopentane dicarboxylic acid, 1-methylcyclohexane carboxylic acid, 2-methylbicyclo[2.2.1]-5-heptene-2-carboxylic acid, 2-methyl-7-oxabicyclo[2.2.1]-5-heptene-2-carboxylic acid, 1-adamantane carboxylic acid, bicyclo[2.2.1]heptane-1-carboxylic acid and bicyclo[2.2.2]octane-1-carboxylic acid or mixtures thereof. 
     
     
         10 . The crosslinkable composition according to  claim 1 , wherein the amount of tertiary acid d) in the composition is in the range of 0.005-0.5 mmol of tertiary acid d) per gram of polyol a). 
     
     
         11 . The crosslinkable composition according to  claim 1 , wherein the polyol a) is selected from polyester polyols, polyacrylate polyols, polycarbonate polyols, polyether polyols, polyurethane polyols, melamine polyols, and mixtures and hybrids thereof, and has a hydroxyl value in the range of 20 to 1,000 mg KOH per gram of polyol and an acid value of 15 mg KOH per gram of polyol or less. 
     
     
         12 . The crosslinkable composition according to any  claim 1  comprising
 from 10 to 90% of weight of polyol a), 
 from 10 to 90% of weight of polyisocyanate crosslinker b), 
 from 0.001 to 10% of weight of catalyst c) 
 from 0.001 to 10% of weight of tertiary acid d), and 
 optionally, from 0.001 to 1% of weight of complexing agent e), 
 based on the total amount of polyol a), crosslinker b), catalyst c), tertiary acid d) and, if present, complexing agent e). 
 
     
     
         13 . Kit of parts for preparing a crosslinkable composition according to  claim 1 , comprising:
 i. a binder module comprising at least one polyol a) and at least one tertiary acid d), and optionally at least one catalyst c) and/or complexing agent e)   ii. a crosslinker module comprising at least one polyisocyanate crosslinker b).   
     
     
         14 . A binder module comprising at least one polyol a) and at least one tertiary acid d) and, optionally at least one complexing agent e) according to  claim 1 . 
     
     
         15 . A method of providing a coating comprising the steps of applying a crosslinkable composition according to  claim 1  to at least a part of an object, preferably the surface of a transportation vehicle, and curing the applied composition, preferably in a temperature range of 5 to 130° C.