Abstract: The present invention relates to the technical field of isocyanates. The present invention provides a method for preparing NCO prepolymers by reacting a stoichiometric excess of an organic isocyanate with an isocyanate-reactive component, the reaction components being mixed together and the mixture being introduced directly into a storage or transport vessel, where it reacts to completion.

Abstract: The present invention relates to the technical field of isocyanates. The present invention provides a method for preparing NCO prepolymers by reacting a stoichiometric excess of an organic isocyanate with an isocyanate-reactive component, the reaction components being mixed together and the mixture being introduced directly into a storage or transport vessel, where it reacts to completion.

Abstract: The invention relates to polyurethanes that can be obtained by reacting a prepolymer based on diphenylmethane diisocyanate (MDI) with compounds that have NCO-reactive groups, and to use thereof.

Abstract: The invention relates to a process for the production of di- and polyisocyanates of the diphenylmethane series and mixtures thereof, in which aniline and formaldehyde are reacted in the presence of an acid catalyst to form di- and polyamines of the diphenylmethane series; the di- and polyamines of the diphenylmethane series are phosgenated, optionally in the presence of a solvent, to obtain a crude di- and polyisocyanate; from the crude di- and polyisocyanate, at least one fraction containing at least 5 wt. % 3-ring and multi-ring MDI and at least one fraction containing at least 95 wt. % 2-ring MDI are separated by distillation, and the acidities of the fraction containing at least 5 wt. % 3-ring MDI and multi-ring MDI, and/or the fraction containing at least 95 wt. % 2-ring MDI are determined analytically; and an acidic compound is added to the fraction containing at least 5 wt. % 3-ring MDI and multi-ring MDI, and/or the fraction containing at least 95 wt.

Abstract: A fraction of diisocyanates of the diphenylmethane series containing at least 95 wt. % binuclear methylenediphenyl diisocyanate is obtained by a) reacting aniline and formaldehyde in the presence of an acid catalyst to produce diamines and polyamines of the diphenylmethane series containing binuclear methylenediphenyl diamine, b) phosgenating the diamines and polyamines produced in a), optionally in the presence of a solvent, to produce a crude diisocyanate and polyisocyanate, and c) separating a fraction containing at least 95 wt. % binuclear methylenediphenyl diisocyanate with a 4,4?-MDI content of over 60 wt. %, a 2,4?-MDI content of 4 to 35 wt. % and a 2,2?-MDI content of 0.01 to 10 wt. %, relative to the mass of the fraction, and a maximum of 20 ppm phenyl isocyanate and optionally a maximum of 50 ppm solvent from the crude diisocyanate and polyisocyanate produced in b) in a single distillation step with optional upstream and/or downstream separation of low-boiling components.

Abstract: The invention relates to a process for the production of di- and polyisocyanates of the diphenylmethane series and mixtures thereof, in which aniline and formaldehyde are reacted in the presence of an acid catalyst to form di- and polyamines of the diphenylmethane series; the di- and polyamines of the diphenylmethane series are phosgenated, optionally in the presence of a solvent, to obtain a crude di- and polyisocyanate; from the crude di- and polyisocyanate, at least one fraction containing at least 5 wt. % 3-ring and multi-ring MDI and at least one fraction containing at least 95 wt. % 2-ring MDI are separated by distillation, and the acidities of the fraction containing at least 5 wt. % 3-ring MDI and multi-ring MDI, and/or the fraction containing at least 95 wt. % 2-ring MDI are determined analytically; and an acidic compound is added to the fraction containing at least 5 wt. % 3-ring MDI and multi-ring MDI, and/or the fraction containing at least 95 wt.

Abstract: A fraction of diisocyanates of the diphenylmethane series containing at least 95 wt. % binuclear methylenediphenyl diisocyanate is obtained by a) reacting aniline and formaldehyde in the presence of an acid catalyst to produce diamines and polyamines of the diphenylmethane series containing binuclear methylenediphenyl diamine, b) phosgenating the diamines and polyamines produced in a), optionally in the presence of a solvent, to produce a crude diisocyanate and polyisocyanate, and c) separating a fraction containing at least 95 wt. % binuclear methylenediphenyl diisocyanate with a 4,4?-MDI content of over 60 wt. %, a 2,4?-MDI content of 4 to 35 wt. % and a 2,2?-MDI content of 0.01 to 10 wt. %, relative to the mass of the fraction, and a maximum of 20 ppm phenyl isocyanate and optionally a maximum of 50 ppm solvent from the crude diisocyanate and polyisocyanate produced in b) in a single distillation step with optional upstream and/or downstream separation of low-boiling components.

Abstract: An NCO-terminated prepolymer is produced by reacting a solid halogenated diol and a polyisocyanate. This prepolymer is useful in the production of flame-retardant polyurethanes.