Low surface energy polyisocyanates and their use in one- or two-component coating compositions

A process for the production of a polyisocyanate mixture

• i) having an NCO content of 5 to 35% by weight and a monomeric diisocyanate content of less than 3% by weight, and prepared from a polyisocyanate adduct,
• ii) containing allophanate groups in an amount such that there are more equivalents of allophanate groups than urethane groups and
• iii) containing fluorine (calculated as F, AW 19) in an amount of 0.001 to 50% by weight,
• wherein the preceding percentages are based on the solids content of the polyisocyanate mixture,
• which comprises
• a) reacting a portion of the isocyanate groups of a polyisocyanate adduct with 0.01 to 500 millimoles, per mole of polyisocyanate adduct, of a compound containing two or more carbon atoms, one or more hydroxyl groups and one or more fluorine atoms to form urethane groups,
• b) adding an allophanatization catalyst prior to, during or after step a),
• c) converting a sufficient amount of the urethane groups formed in step a) to allophanate groups to satisfy the requirements of ii) and
• d) terminating the allophanatization reaction at the desired NCO content by adding a catalyst poison and/or by thermally deactivating the catalyst and recovering the polyisocyanate mixture without removing monomeric diisocyanates.