MEZCLAS DE POLIISOCIANATOS MODIFICADAS MEDIANTE POLIETERES DISPERSABLES

LA INVENCION TRATA DE MEZCLAS DE POLIISOCIANATOS MODIFICADAS CON POLIETER DISPERSABLES EN AGUA, UN PROCEDIMIENTO PARA SU PREPARACION Y SU UTILIZACION COMO COMPONENTES INICIALES PARA LA FORMACION DE PLASTICOS DE POLIURETANO, EN PARTICULAR COMO RETICULANTES PARA LIGANTES DE PINTURAS HIDROSOLUBLES O DISPERSABLES EN AGUA O COMO LIGANTES, CON GRUPOS QUE REACCIONAN CON LOS GRUPOS DE ISOCIANATOS. The reaction of a monomer deficient polyisocyanate containing at least two diisocyanate molecules with a monofunctional polyethyleneoxide polyether alcohol under allophanate production conditions gives a water dispersible polyisocyanate mixture. A water dispersible polyisocyanate mixture based on aliphatic, cycloaliphatic, araliphatic and/or aromatic diisocyanate with (a) a mean isocyanate functionality of at least 2.0; (b) an isocyanate group content (calculated as NCO, molecular weight = 42) of 5.0-25.0 wt.%; and (c) a content of bound ethylene oxide units inside the polyether chain (calculated as C2H4O, molecular weight = 44) of 2-50 wt.%, where the polyether chain contains a statistical mean of 5-35 ethylene oxide units, is new. The polyether chain is bonded, via allophanate groups, to at least 60 mol% polyisocyanate molecules synthesized from at least two diisocyanates. An Independent claim is included for: a process for production of a water dispersible polyisocyanate mixture by reaction of (A) a polyisocyanate component of mean functionality 2.0-5.0 with a content of aliphatic, cycloaliphatic, araliphatic, and/or aromatically bonded isocyanate groups (calculated as NCO, molecular weight = 42) of 8.0-27.0 wt.% and a content of diisocyanate monomers of at least 1 wt.% with (B) a monovalent polyalkyleneoxide polyether alcohol containing a statistical mean of 5-35 ethylene oxide units, at an NCO/OH equivalent ratio of 6:1 to 400:1, so that at least 60% of the urethane groups formed as a result of the NCO/OH reaction re-react to form allophanate groups. The weight ratio of the starting compounds is selected so that the resultant reaction product corresponds to the conditions in (a) to (c) above;