The invention provides novel solvent-free two-component polyurethane coating agents for preparing high quality yellowing-free coatings and a process for the preparation thereof. The coating agents include binder mixtures containing a polyisocyanate component with a viscosity at 23 C. of 2,000 to 150,000 mPas, a NCO content of 14 to 23 wt. % and a calculated mean NCO functionality of at least 2.8; a polyol component with a mean OH functionality 3, a viscosity at 23 C. of 5,000 to 150,000 mPas and a hydroxyl value of 400 to 700 mg KOH/g; and optionally one or more catalysts.
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