Aqueous emulsion coating composition comprising an autoxidisable fatty acid modified polyester

Abstract

An aqueous coating composition comprising an autoxidisable fatty acid modified polyester resin having ≧40 wt % of fatty acid residues; a Tg in the range of from −70 to +20° C.; an acid value less than 40 mg KOH/g; a Mw in the range of from 5,000 to 125,000 g/mol; >5 wt % of ring structures; and said composition having a co-solvent content less than 20 wt % by weight of solids; a solids content >38 wt %; and when in the form of the film having a telegraphing value of less than 35 gloss units.

1 . An aqueous coating composition comprising an autoxidisable fatty acid modified polyester resin, said resin having:
 i) >40 wt % of fatty acid residues;   ii) a Tg in the range of from −70 to +20° C.;   iii) an acid value less than 40 mg KOH/g;   iv) a Mw in the range of from 5,000 to 125,000 g/mol;   v) >5 wt % of ring structures; and   said composition having   a) a co-solvent content less than 20 wt % by weight of solids;   b) a solids content >38 wt %;   said composition when in the form of the film having a telegraphing value of less than 35 gloss units;   where the telegraphing value is the difference between an initial smooth gloss value minus an initial rough gloss value of the film, where   the initial smooth gloss value is the gloss when the film is cast on smooth PVC (R z =1 μm [±0.25 μm]);   the initial rough gloss value is the gloss when the film is cast on rough PVC (R z =25 μm [±5 μm]); and where   each film has a dry film thickness of 68 μm [±6 μm]; and   each initial gloss value is measured at a 20° angle, one day (24 h) after the film has been cast.   
     
     
         2 . An aqueous coating composition according to  claim 1  wherein the autoxidisable fatty acid modified polyester resin comprises at least 5 wt % of ring structures. 
     
     
         3 . An aqueous coating composition according to  claim 1  wherein the autoxidisable fatty acid modified polyester resin comprises <5 wt % of TMA (trimellitic acid and or trimellitic anhydride). 
     
     
         4 . An aqueous coating composition according to  claim 1  wherein the autoxidisable fatty acid modified polyester resin comprises <15 wt %, of phthalic acid, phthalic anhydride and or benzoic acid. 
     
     
         5 . An aqueous coating composition according to  claim 1  wherein the autoxidisable fatty acid modified polyester resin comprises <6 wt % of glycerol. 
     
     
         6 . An aqueous coating composition according to  claim 1  wherein the fatty acid residues have an iodine number of at least 50 gl 2 /100 g fatty acid. 
     
     
         7 . An aqueous coating composition according to  claim 1  wherein the autoxidisable fatty acid modified polyester resin is obtained from components:
 i) 15 to 35 wt % of isophthalic acid and or hexahydrophthalic anhydride (HHPAN); 
 ii) 0 to 2 wt % of glycerol; 
 iii) 45 to 80 wt % of fatty acid residues having an iodine value between 50 and 180 gl 2 /100 g; 
 wherein the fatty acid contains less than 10 wt % of fatty acids that contain 3 or more double bonds; 
 iv) 0 to 5 wt % of TMA (trimellitic acid and or trimellitic anhydride); 
 where i)+ii)+iii+iv)=100%; 
 wherein the fatty acid contains less than 10 wt % of fatty acids that contain 3 or more double bonds; 
 wherein the ND×AV value is <20 mgKOH/g; and 
 wherein the composition comprises: 
 4 to 8 wt % of a surfactant based on the weight of the total resin material, which is a mixture of at least one anionic and at least one non-ionic surfactant; and wherein the anionic surfactant part is 2 to 5 wt % based on the weight of the total resin material. 
 
     
     
         8 . An aqueous coating composition according to  claim 1  wherein the autoxidisable fatty acid modified polyester resin is obtained from components:
 i) 15 to 35 wt % of isophthalic acid and or hexahydrophthalic anhydride (HHPAN); 
 ii) 0 to 2 wt % of glycerol; 
 iii) 45 to 63 wt % of fatty acid residues having an iodine value between 60 and 180 gl 2 /100 g; 
 wherein the fatty acid residues contain less than 10 wt % of linolenic acid; 
 wherein part of the fatty acid residues is derived from a short chain fatty acids RCOOH where R comprises a 1,3- or 1,4-dienyl carbon skeleton and wherein the longest carbon skeleton is C10; 
 wherein 1 to 20 wt % of short chain fatty acid residues by weight of the resin is used; 
 iv) 0 to 5 wt % of TMA (trimellitic acid and or trimellitic anhydride); 
 where i)+ii)+iii+iv)=100%; 
 wherein the ND×AV value is <20 mgKOH/g; and 
 wherein the composition comprises: 
 4 to 8 wt % of a surfactant based on the weight of the total resin material, which is a mixture of at least one anionic and at least one non-ionic surfactant; and wherein the anionic surfactant part is 2 to 5 wt % based on the weight of the total resin material. 
 
     
     
         9 . An aqueous coating composition according to  claim 8  wherein the short chain fatty acids comprising a 1,3- or 1,4-dienyl structure are selected from the group consisting of 2,4-hexadienoic acid, 2-methyl-5-isopropylhexa-2,5-dienoic acid, 2,3-octadienoic acid and mixtures thereof. 
     
     
         10 . An aqueous coating composition according to  claim 1  comprising at least:
 i) 42 to 65 wt % of the autoxidisable fatty acid modified polyester; 
 ii) 0 to 20 wt % of co-solvent; and 
 iii) 15 to 58 of water; 
 where i)+ii)+iii)=100%. 
 
     
     
         11 . An aqueous coating composition according to  claim 1  comprising resin solids comprising at least 50 wt % of the autoxidisable fatty acid modified polyester resin on total resin solids. 
     
     
         12 . An aqueous coating composition according to  claim 1  comprising <13 wt % on coating composition solids of nitrogen containing molecules with an evaporation rate <0.1. 
     
     
         13 . An aqueous coating composition according to  claim 1  wherein the composition comprises <13 wt % of N-methylpyrrolidone by weight of solids. 
     
     
         14 . An aqueous coating composition according to  claim 1  comprising at least:
 i) 20 to 45 wt % of the autoxidisable fatty acid modified polyester resin; 
 ii) 10 to 60 wt % of water; and 
 iii) 20 to 45 wt % of pigment; 
 where i)+ii)+iii)=100%; and 
 iv) 0 to 5 wt % of co-solvent by weight of solids; 
 v) 0.1 to 4 wt % of thickener by weight of solids; and 
 vi) 0 to 9 wt % of dispersing agent by weight of solids. 
 
     
     
         15 . An aqueous coating composition according to  claim 1  wherein the initial rough gloss value minus the rough gloss value measured at 4 days after film formation is less than 14 gloss units. 
     
     
         16 . A substrate coated with an aqueous coating composition according to  claim 1 . 
     
     
         17 . A method for coating a substrate comprising applying the aqueous coating composition according to  claim 1  to the substrate and then drying the aqueous composition to form a coated substrate. 
     
     
         18 . A paint comprising an aqueous coating composition according to  claim 1 .