Coating composition comprising autoxidisable component

Abstract

An aqueous emulsion coating composition comprising an autoxidisable vinyl oligomer having ≧20 wt % of unsaturated fatty acid residue; Tg from −50 to +15° C.; Mw from 2,500 to 40,000 g/mol; polydispersity from 2 to 12, said composition having ≦15% co-solvent by weight of solids, ≦13% NMP by weight of solids ≧38% solids by weight of composition; said composition when in the form of a coating having a telegraphing value defined as the difference in gloss at a 20° angle of between a film cast on rough PVC and a film cast on smooth PVC of 10 gloss units.

1 . An aqueous emulsion, coating composition that comprises an autoxidisable vinyl oligomer where:
 I) said autoxidisable vinyl oligomer has:   i) fatty acid residue in an amount greater than or equal to 20% by weight of the autoxidisable vinyl oligomer;   ii) a glass transition temperature (T g ) from −50° C. to +15° C.;   iii) an acid value less than 40 mg KOH/g;   iv) a weight average molecular weight (M w ) from 2,500 to 40,000 g/mol;   v) a polydispersity (PDi) from 2 to 12;   II) said composition has:   a) a co-solvent content less that 25% by weight of solids;   b) a N-methylpyrrolidone content less than 13% by weight of solids;   c) a solids content greater than or equal to 38% by the total weight of said composition; and   III) said composition when in the form of the film has a telegraphing value of less than 10 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 microns [μm] [±5 μm]); and where   each film has a dry film thickness of 52 μm [±6 μm]; and   each initial gloss value is measured at a 20° angle, one day (24 hours) after the film has been cast.   
     
     
         2 . An aqueous autoxidisable coating composition according to  claim 1  comprising an autoxidisable vinyl oligomer obtained by a process comprising steps of:
 I) polymerising ethylenically unsaturated vinyl monomers comprising: 
 i) 30% to 70% of at least one monomer G selected from hydroxylalkyl(meth)acrylates and epoxy functional vinyl monomers; 
 ii) 30% to 70% of at least one other ethylenically unsaturated vinyl monomer; and 
 iii) <1% of chlorine containing monomers; 
 where the percentages are by weight of total monomers; 
 II) reacting the oligomer obtained in step I) with fatty acids having an average iodine value in the range of 80 to 180 gl 2 /100 g fatty acid; 
 where the autoxidisable vinyl oligomer has 
 i) oligomeric backbone in an amount from 35% to 62% by weight of the oligomer; 
 ii) fatty acid residue in an amount from 38% to 65% by weight of the oligomer; 
 iii) a Tg from −50 to 15° C.; 
 iv) a Mw from 6500 to 25000 g/mol; and 
 v) a PDi from 2 to 8; 
 said composition having 
 a) a co-solvent content <15 wt % by weight of solids; 
 b) a N-methylpyrrolidone content <13 wt % by weight of solids; 
 c) heterocyclic amine containing solvent content of 0 wt % by weight of solids; 
 d) a solids content >38 wt %; 
 e) a pH in the range of from 4.1 to 8.4; and 
 where said composition when in the form of a coating has a telegraphing value (as defined in  claim 1 ) of less than 10 gloss units. 
 
     
     
         3 . An aqueous autoxidisable coating composition according to  claim 1  where 0% of glycidyl esters of unsaturated fatty acids are used in the preparation of the autoxidisable vinyl oligomer. 
     
     
         4 . An aqueous autoxidisable coating composition according  claim 1  where the autoxidisable vinyl oligomer, if carboxylic acid functional conforms to the following relationship:
   ND×AV<22
 
 where ND=neutralization degree of the acid groups on the oligomer; and where AV=acid value. 
 
     
     
         5 . An aqueous autoxidisable coating composition according to  claim 1  comprising <5% of N-methylpyrrolidone by weight of solids. 
     
     
         6 . An aqueous autoxidisable coating composition according to  claim 1  comprising <13% by weight of solids, of nitrogen containing molecules with an evaporation rate <0.1 which are either aromatic, heterocyclic or which are aromatic and aliphatic primary and secondary (di)amines with the proviso that the amount of nitrogen in such molecules is >5% by weight of the molecule. 
     
     
         7 . An aqueous emulsion coating composition according to  claim 1  where said composition comprises:
 i) 38% to 65% of the autoxidisable vinyl oligomer; 
 ii) 0 to 20% of co-solvent; and 
 iii) 15% to 58% of water; 
 where the percentages are by weight of the composition and i)+ii)+iii)=100%. 
 
     
     
         8 . An aqueous emulsion coating composition according to  claim 1  where said composition comprises:
 i) 20% to 45% of TiO 2 ; 
 ii) 20% to 45% of the autoxidisable vinyl oligomer; 
 iii) 0 to 10% of co-solvent; 
 iv) 0.1% to 3% of thickener; 
 v) 0 to 5% of dispersing agent; and 
 vi) 25% to 60% water; 
 where the percentages are by weight of the composition and 
 i)+ii)+iii)+iv)+v)=100%. 
 
     
     
         9 . A method for preparing an autoxidisable vinyl oligomer, where said autoxidisable vinyl oligomer is capable of forming a coating composition that when in the form of the film has a telegraphing value of less than 10 gloss units (as defined in  claim 1 ); the process comprising the steps of:
 I) polymerising ethylenically unsaturated vinyl monomers comprising:   i) 30% to 70% of at least one monomer G selected from hydroxylalkyl(meth)acrylates and epoxy functional vinyl monomers;   ii) 30% to 70% of at least one other ethylenically unsaturated vinyl monomer; and   iii) <1% of chlorine containing monomers;   where the percentages are by weight of total monomers;   II) reacting the oligomer obtained in step I) with fatty acids having an average iodine value in the range of 80 to 180 gl 2 /100 g fatty acid;
 to obtain an autoxidisable vinyl oligomer having 
   i) oligomeric backbone in an amount from 35% to 62% by weight of the oligomer;   ii) fatty acid residue in an amount from 38% to 65% by weight of the oligomer;   iii) a T g  from −50 to 15° C.;   iv) a Mw from 6500 to 25000 g/mol; and   v) a PDi from 2 to 8.   
     
     
         10 . A method as claimed in  claim 9 , where said autoxidisable vinyl oligomer is capable of forming a coating composition that has
 a) a co-solvent content ≦15% by weight of solids;   b) a N-methylpyrrolidone content ≦13% by weight of solids;   c) heterocyclic amine containing solvent content of 0 wt % by weight of solids;   d) a solids content ≧38% by weight of the composition; and   e) a pH from 4.1 to 8.4.   
     
     
         11 . An autoxidisable vinyl oligomer obtained and/or obtainable by a process as claimed in either  claim 9 . 
     
     
         12 . A coating composition comprising an autoxidisable vinyl oligomer as claimed in  claim 11 . 
     
     
         13 . A coating composition as claimed in  claim 12  where the composition comprises:
 a) a co-solvent content ≦15% by weight of solids; 
 b) a N-methylpyrrolidone content ≦13% by weight of solids; 
 c) heterocyclic amine containing solvent content of 0 wt % by weight of solids; 
 d) a solids content ≧38% by weight of the composition; and 
 e) a pH from 4.1 to 8.4; and
 where said composition is in the form of the film, the film has a telegraphing value (as defined in  claim 1 ) of less than 10 gloss units. 
 
 
     
     
         14 . A coating composition as claimed in  claim 1 , in which the an autoxidisable vinyl oligomer is present in an amount from 38 to 65% by weight of the composition. 
     
     
         15 . A coating obtained and/or obtainable by a coating composition as claimed in  claim 1  and having a telegraphing value (as defined in  claim 1 ) of less than 10 gloss units. 
     
     
         16 . A substrate coated with a coating as claimed in  claim 15 . 
     
     
         17 . A method of coating a substrate comprising the steps of
 i) applying a coating composition as claimed in  claim 1  to a substrate;   ii) drying the substrate to form a coating thereon;   where the coating has a telegraphing value (as defined in  claim 1 ) of less than 10 gloss units.   
     
     
         18 . Use of an autoxidisable vinyl oligomer and/or a coating composition as claimed in  claim 1  for the purpose of obtaining coatings having a telegraphing value (as defined in  claim 1 ) of less than 10 gloss units. 
     
     
         19 . A method of manufacture of an autoxidisable vinyl oligomer and/or a coating composition as claimed in  claim 1  for the purpose of obtaining coatings having a telegraphing value (as defined in  claim 1 ) of less than 10 gloss units.