Aqueous autoxidisable coating composition

摘要

An aqueous coating composition comprising an autoxidizable polyester resin having ≧30 wt % of fatty acid residues; a Tg in the range of from −60° C. to +35° C.; an acid value greater than 15 mg KOH/g and less than 75 mg KOH/g; a Mw in the range of from 2,500 to 100,000 g/mol; the composition having a co-solvent content less that 15 wt % by weight of total composition; a solids content >30 wt %; and when in the form of a film, the composition has a telegraphing value of less than 20 gloss units.

主权项

1. An aqueous coating composition comprising an autoxidisable urethanised polyesteramide resin which comprises <5 wt % of trimellitic acid and/or trimellitic anhydride, wherein the autoxidisable urethanised polyesteramide resin is obtained from components comprising:
i) 10 to 45 wt % of a cyclic anhydride; iii) 33 to 65 wt % of fatty acid residues having an iodine number between 80 and 155 g I2/100 g fatty acid, wherein the fatty acid residues contain less than 10 wt % of fatty acid residues that contain 3 or more double bonds; iv) 10 to 35 wt % of a hydroxyl functional amine; and v) 0.5 to 7 wt % of a polyisocyanate; wherein i)+iii)+iv)+v)=100%; and wherein the autoxidisable urethanised polyesteramide resin has: (I) a ND×AV value which is in a range of from 22 to 65 mg KOH/g, where ND is a neutralization degree of the acid groups and AV is an acid value of the autoxidisable urethanised polyesteramide resin; (II) a Tg in the range of from −60° C. to +35° C.; (III) an acid value greater than 15 mg KOH/g and less than 75 mg KOH/g; and (IV) a Mw in the range of from 2,500 to 100,000 g/mol; wherein said composition has: a) a co-solvent content ≦15 wt % based on the total weight of the composition; b) a solids content >30 wt %; and wherein said composition when in the form of a film has a telegraphing value of less than 20 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 (Rz=1 μm [±0.25 μm]); the initial rough gloss value is the gloss when the film is cast on rough PVC (Rz=25 μm [±5 μm]); and wherein 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 h) after the film has been cast.