Water-soluble or water-dispersible polyisocyanate composition, a process for its preparation and its use in coating compositions
AssigneeBayer Aktiengesellschaft
InventorsLutz Schmalstieg, Wolfgang Kremer, Martin Brahm, Joachim Probst, Werner Kubitza
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Abstract
A water-dispersible polyisocyanate composition obtained by the partial urethanization of the isocyanate groups of 2,4- and/or 2,6-diisocyanatotoluene with monohydric and polyhydric alcohols, a process for its production, its use as the binder for an aqueous two-component coating composition in combination with a water-soluble or water-dispersible polyhydroxyl component and coatings for water-resistant sheet-form substrates prepared from this coating composition.
Claims11
A water-dispersible or water-soluble polyisocyanate composition obtained by the partial urethanization of the isocyanate groups of 2,4- and/or 2,6-diisocyanatotoluene by reaction with monohydric and polyhydric alcohols, wherein the polyisocyanate composition has, based on solids,
- a) an average NCO functionality of 1.9 to 3.3,
- b) a content of isocyanate groups (expressed as NCO, molecular weight 42) of 8 to 18% by weight,
- c) a content of ethylene oxide units (expressed as C.sub.2 H.sub.4 O, molecular weight 44) of 5 to 40% by weight which are arranged in terminal polyether chains containing an average of 7 to 25 alkylene oxide units in which at least 70 mol-% of the alkylene oxide units are ethylene oxide units, and
- d) a urethane group content (expressed as CHNO.sub.2, molecular weight 59) of 13 to 33% by weight.
A process for the production of a polyisocyanate composition which has
- a) an average NCO functionality of 1.9 to 3.3,
- b) a content of isocyanate groups (expressed as NCO, molecular weight 42) of 8 to 18% by weight,
- c) a content of ethylene oxide units (expressed as C.sub.2 H.sub.4 O, molecular weight 44) of 5 to 40% by weight which are arranged in terminal polyether chains containing an average of 7 to 25 alkylene oxide units in which at least 70 mol-% of the alkylene oxide units are ethylene oxide units, and
- d) a urethane group content (expressed as CHNO.sub.2, molecular weight 59) of 13 to 33% by weight,
- which comprises reacting at an NCO:OH equivalent ratio of 4:1 to 120:1
- A) a polyisocyanate component having an average NCO functionality of 2.7 to 4.1, a content of isocyanate groups of 12 to 20% by weight and a content of urethane groups of 17 to 29% by weight, and containing at least one urethane-modified polyisocyanate produced by partial urethanization of the isocyanate groups of 2,4-and/or 2,6-diisocyanatotoluene with
- B) a monofunctional hydrophilic polyether component containing at least one monohydric polyether alcohol containing an average of 7 to 25 alkylene oxide units in which at least 70 mol-% of the alkylene oxide units are ethylene oxide units, to form additional urethane groups.
An aqueous two-component coating composition wherein the binder contains, in quantities which correspond to an NCO:OH equivalent ratio of 0.6:1 to 2:1,
- I) a water-dispersible or water-soluble polyisocyanate composition obtained by the partial urethanization of the isocyanate groups of 2,4- and/or 2,6-diisocyanatotoluene by reaction with monohydric and polyhydric alcohols, wherein the polyisocyanate composition has, based on solids,
- a) an average NCO functionality of 1.9 to 3.3,
- b) a content of isocyanate groups (expressed as NCO, molecular weight 42) of 8 to 18% by weight,
- c) a content of ethylene oxide units (expressed as C.sub.2 H.sub.4 O, molecular weight 44) of 5 to 40% by weight which are arranged in terminal polyether chains containing an average of 7 to 25 alkylene oxide units in which at least 70 mol-% of the alkylene oxide units are ethylene oxide units, and
- d) a urethane group content (expressed as CHNO.sub.2, molecular weight 59) of 13 to 33% by weight, and
- II) a water-soluble or water-dispersible polyhydroxyl component.
Dependencies are inferred from the claim text.