Huels Aktiengesellschaft

Degussa Aktiengesellschaft

Degussa-huels Aktiengesellschaft

Hartwig Lange

Klaus Janischewski

Dirk Reichel

Martina Ortelt

A stable and high-solids aqueous dispersion of blocked isocyanates, containing auxiliary solvent, is prepared by (1) preparing a solution of a polyisocyanate mixture of from 20-70% by weight of a blocked, hydrophilically modified polyisocyanate (A) and from 30-80% by weight of a blocked, hydrophobic polyisocyanate (B) in an auxiliary solvent (G) and (2) adding water to this solution, with intensive mixing, in an amount which is such as to give a two-phase system comprising a disperse polyisocyanate phase and a continuous, aqueous phase containing auxiliary solvent. In a preferred embodiment of the invention dispersions are prepared which are virtually free from auxiliary solvent, by first adding a portion of water to the solution (1), substantially removing the auxiliary solvent with intensive mixing and then adding a second portion of water with intensive mixing to the mixture comprising the polyisocyanates (A) and (B) and the first portion of water.

Stable and high solids aqueous dispersions of blocked polyisocyanates

Hydrophilic, hydrolytically-stable synthetic resins obtainable by reacting a hydroxyl-functional synthetic resin such as a ketone, ketone/aldehyde and/or urea/aldehyde and/or a hydrogenated product of the hydroxyl-functional synthetic resin thereof with a polycarboxylic acid, polycarboxylic anhydride, polycarboxylic ester and/or polycarbonyl halide, where 70-100 mol % of the polycarboxylic acid and/or derivatives is linked chemically via an ester linkage to the hydroxyl-functional synthetic resin by way of only one single function and 0-30 mol % of the acid and/or acid derivative is so linked by way of more than one function.

Hydrophilic synthetic resins, esterified for stability to hydrolysis,

Aqueous resin dispersions obtainable by reaction, or partial reaction, of

Aqueous resin dispersions

A one-component aqueous coating system comprising (A) a hydrophilic polyacrylate polyol or polyesterpolyol containing at least one hydroxyl group, (B) a polyisocyanate which is water resistant at room temperature or a blocked polyisocyanate, (C) optionally a pigment or a conventional paint auxiliary, such as an antifoam, a levelling agent, a catalyst or a thixotropic agent, and a further reactive additive component (D), in a quantity of from 2 to 20% by weight, based on the overall solids content of (A), (B) and (D), the additive component (D) being characterized in that it contains at least one reactive OH, NH, NH.sub.2 or SH group and has a functionality of at least 1.5 to 3.0 relative to the crosslinking agent (B), a solubility in water of below 2% by weight and a molecular weight of 500-2000 g/mol.

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Haltern, Germany

Hartwig Lange