Patent EP-2662134-A1 (EP)
Inventor: SCHARF SABINE
IPC: C09D7/65
Filed: 2013-05-08
Abstract: Producing transparent microcapsules comprises: (a) preparing a solution; (b) adding 0.02-0.13 wt.% of an emulsifier consisting of an anionic emulsifier and a nonionic emulsifier in a ratio of 1:3-3:1, preferably 1:2-2:1; (c) adjusting the pH-value of the resulting solution to be 2.5-6; (d) optionally adding a defoamer consisting of octanol and decanol in a concentration of 0-0.6 wt.% based on the total weight of the preparation; and (e) adding 9-42 wt.% of at least one hydrophobic material, preferably air-drying alkyd resins and/or oils including linseed oil and desiccated linseed oil. Producing transparent microcapsules comprises: (a) preparing a solution consisting of (i) 0.1-1 wt.% of ammonium- and/or alkali metal chloride, (ii) 0-0.7 wt.% of an aromatic alcohol consisting of dihydroxy- and/or trihydroxy benzene including resorcinol (preferred), pyrogallol and/or phloroglucinol, (iii) 0.1-3.5 wt.% of an amine- or amide-component consisting of amine or amide having at least two amino groups including melamine, diaminohexane or urea (preferred) and/or cyanamide and (iv) 0.3-2 wt.% of a protective colloid, which is soluble in water and an oil-in-water emulsion, preferably consisting of polyvinylpyrrolidone, polyvinyl alcohol, polyvinyl acetate, poly[1-(N-2-methyl-propanesulfonic acid) carbomylethylene], gum arabic and/or poly(ethylene-alt-maleic anhydride) (EMA) and EMA in water, where the total concentration of the non-soluble ingredients is 1.5-7.2 wt.%; (b) adding 0.02-0.13 wt.% of an emulsifier consisting of an anionic emulsifier and a nonionic emulsifier in a ratio of 1:3-3:1, preferably 1:2-2:1; (c) adjusting the pH-value of the resulting solution to be 2.5-6; (d) optionally adding a defoamer consisting of octanol and decanol in a concentration of 0-0.6 wt.% based on the total weight of the preparation; (e) adding 9-42 wt.% of at least one hydrophobic material, preferably air-drying alkyd resins and/or oils including linseed oil and desiccated linseed oil based on the total weight of the preparations; (f) adding 0.5-13 wt.% of an aldehyde component consisting of formaldehyde (preferred), glutaraldehyde, and/or glyoxal based on the total weight of the preparation; (g) tempering the obtained mixture at 40-70[deg] C for 1-5 hours under mixing, such that the conditions of the mixing are selected so that it initially forms an emulsion, whose droplets have a number average droplet size of 15-350 mu m; and (h) recovering the microcapsules by filtration, washing and drying, and optionally classifying. Independent claims are included for: (1) transparent microcapsules obtained by the method, comprising microcapsule dispersions; (2) a coating material comprising the transparent microcapsules; (3) a microcapsule dispersion comprising the microcapsules; and (4) application method for the coating material, comprising applying the coating material by conventional dipping, brushing, rolling, flow coating, casting, high pressure spraying, high rotary atomization, electrostatic-spraying, airless spraying, high volume low pressure-gun, air mix spraying or spray gun.