Patent ID: 6566438
Filing Date: 2003-05-20
Classification: C08G,C09D

Abstract:
A polyurethane/polymer hybrid dispersion with high film hardness comprising:(A) from 3 to 25% by weight of a polyol component comprising (i) from 2 to 20% by weight of a high molecular mass polyol having two or more polyisocyanate-reactive hydroxyl groups and a molar mass of from 500 to 4000 daltons, and (ii) from 0.5 to 5% by weight of a low molecular mass polyol having two or more polyisocyanate-reactive hydroxyl groups and a molar mass of from 50 to 500 daltons; (iii) from 0.5 to 3% by weight of a low molecular mass, anionically modifiable polyol having two or more polyisocyanate-reactive hydroxyl groups and also one or more polyisocyanate-inert carboxyl groups and a molar mass of from 100 to 200 daltons, (B) from 2 to 20% by weight of a polyisocyanate component comprising one or more polyisocyanates, polyisocyanate homologs and/or polyisocyanate derivatives having two or more aliphatic and/or aromatic isocyanate groups; (C) from 0 to 6% by weight of a solvent component consisting of (i) at least one polyisocyanate-inert organic solvent which following the preparation of the polyurethane/polymer hybrid dispersion may remain therein or may be removed in part or in whole by distillation, and/or (ii) at least one polyisocyanate-inert reactive diluent comprising at least one polyisocyanate-inert organic compound having one or more free-radically polymerizable double bonds; (D) from 0.15 to 1.5% by weight of a neutralizing component comprising at least one organic or inorganic base, (E) from 0.1 to 1% by weight of a chain extender component comprising one or more polyamines having two or more polyisocyanate-reactive amino groups, (F) from 5 to 40% by weight of a monomer component comprising one or more monomers having one or more free-radically polymerizable double bonds, (G) from 0.01 to 1.5% by weight of a free-radical initiator component comprising of at least one lipophilic free-radical initiator and water as the remainder, obtained by first preparing in reaction stage (a) a polyurethane base dispersion by (a1) reacting components (A), (B) and (C) in the presence or absence of a catalyst, to give a polyurethane prepolymer, (a2) transferring the polyurethane prepolymer from stage (a1) to the dispersion medium, water, and neutralizing it directly or indirectly using the neutralizing component (D), and subsequently (a3) reacting the polyurethane prepolymer dispersion from stage (a2) with the chain extender component (E), which has been dissolved in fractions of the dispersion medium removed prior to the addition, and then in reaction stage (b) preparing a polyurethane/polymer hybrid dispersion by (b1) adding to the polyurethane base dispersion from stage (a3) a preprepared mixture of components (F) and (G), and subsequently (b2) by means of the thermal decomposition of component (G), conducting a free-radical polymerization of component (F) within the micelles of the polyurethane base dispersion.