Patent ID: 6620893
Filing Date: 2003-09-16
Classification: C08G,C09D

Abstract:
A method of producing urethane-modified, aqueous polyester resins which dry by oxidative crosslinking and which have an acid number of 15-50 mg KOH/g, comprising the steps of reactinga) 15-40% by weight of a prepolymer which is produced in situ and which is the reaction product of a1) a diisocyanate component consisting of at least one organic diisocyanate of molecular weight range 168-294, and a2) hydroxypivalic acid, wherein the ratio of a1:a2 results in a starting equivalent ratio of NCO:OH=1:1 to 5:1,in 80-95% by weight organic solution withb) 60-90% by weight of a polyester resin with an OH number of 30-100 mg KOH/g and an acid number&lE;5 mg KOH/g, which is produced by the reaction of b1) 20-70% by weight of a monocarboxylic acid component, at least 60% by weight of which consists of at least one unsaturated fatty acid, b2) 10-40% by weight of a dicarboxylic acid, of a dicarboxylic anhydride or of a mixture of these compounds, b3) 0-15% by weight of one or more diols, and b4) 5-35% by weight of one or more polyols with an OH-functionality>2, wherein b1, b2, b3 and b4 add up to 100%, andc) 0-15% by weight of one or more polyols with an OH-functionality&gE;2, wherein a, b and c add up to 100%, subsequently dispersing the reaction product in water, and converting the carboxyl groups in the reaction product into carboxylate groups by adding 0.5-1.2 equivalents (with respect to the carboxyl groups present) of a base during the reaction of a+b+c or directly before, during or after the dispersion.