06-02-1986 дата публикации
Номер: DE3428204A1
The invention relates to a process for the preparation of aqueous emulsions of air-drying paint (surface coating, lacquer) binders based on modified alkyd resins. From 25 to 50% by weight of a fatty acid-modified alkyd resin having an oil content of from 30 to 60% by weight, a polyethylene glycol (PEG) content of from 6 to 16% by weight, an acid number of from 30 to 60 mg of KOH/g, essentially based on the carboxyl groups of from 10 to 20% by weight of trimellitic anhydride, a hydroxyl number of from 20 to 100 mg of KOH/g and a limiting viscosity number (intrinsic viscosity) [ eta ] of from 6 to 8 ml/g (DMF/20 DEG C) are reacted with from 75 to 50% by weight of an acid-free, fatty acid-modified alkyd resin having an oil content of from 15 to 60% by weight, an acid number of less than 3 mg of KOH/g, a hydroxyl number of from 30 to 150 mg of KOH/g and a limiting viscosity number [ eta ] of from 7 to 10 ml/g (DMF/20 DEG C) by esterification or joint reaction with a diisocyanate until the limiting viscosity number [ eta ] has risen by from 1 to 4 units. The binder, after neutralisation by means of bases and addition of small amounts of organic auxiliary solvents, is emulsified in water. The binder systems have a low content of bases and give paints having excellent processing and technical properties.
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