Abstract: The present invention relates to a process for the purification of a product stream from isocyanate synthesis, wherein the isocyanate converted to the gas phase from the product stream is continuously deposited on a rotating cooled roller and removed from the roller. The present invention further relates to an apparatus for the purification of a product stream from isocyanate synthesis, wherein the apparatus has both a heated roller and a condensation roller.

Abstract: The invention relates to a method for recovering a diisocyanate that is solid at room temperature from a distillation residue originating from a production process of the diisocyanate, comprising the following steps: (i) mixing the distillation residue with at least one polyisocyanate on the basis of one or more diisocyanates different from the diisocyanate that is solid at room temperature, in such a way that a mixture is obtained that contains 70 to 90 wt. % of the distillation residue and 10 to 30 wt. % of the at least one polyisocyanate, each relative to the mixture, (ii) subjecting the mixture to distillation in a thin-film evaporator and/or a downflow evaporator, thereby obtaining a sump discharge and a gaseous product stream, and (iii) condensing the gaseous product stream and obtaining a solid containing the diisocyanate that is solid at room temperature, the at least one polyisocyanate in step (i) having a residual monomer content of ?3.0 wt.

Abstract: The invention relates to a method for extracting diisocyanates that are solid at room temperature from a distillation residue, comprising the following steps: (i) providing at least one residue containing diisocyanates that are solid at room temperature, and (ii) treating the residue at a temperature of ?120° C. to <200° C. so as to obtain diisocyanates that are solid at room temperature, the residue provided in step (i) containing ?32 to ?60 wt. % of bitumen and the treatment in step (ii) being carried out in at least one thin-film evaporator and/or falling-film evaporator.

Abstract: The invention relates to a method for recovering a diisocyanate which is solid at room temperature from a distillation residue from a process for producing the diisocyanate, comprising the following steps: (i) mixing the distillation residue with a bitumen such that a mixture is obtained which contains 70 to 90 wt % of the distillation residue and 10 to 30 wt % of the bitumen, each in relation to the mixture, (ii) distilling the mixture in a thin-film evaporator or a falling film evaporator to obtain a sump discharge and a gaseous product stream, (iii) condensing the gaseous product stream and obtaining a solid containing the diisocyanate which is solid at room temperature. The invention further relates to the use of a thin-film evaporator or falling film evaporator, to a composition containing the diisocyanate which is solid at room temperature, and to a method for producing an elastomer from this composition and to the elastomer itself.

Abstract: The invention relates to a method for recovering monomer diisocyanates, which are solid at room temperature, from a distillation residue, said method comprising the following steps: (i) preparing at least one residue which contains diisocyanates, which are solid at room temperature, and (ii) separating the residue in at least one kneader-dryer, paddle-dryer and/or roller-dryer in the presence of less than 2 wt % bitumen, based on the mass of the residue prepared in step (i), into a gaseous portion, containing monomer diisocyanate that is solid at room temperature, and a brittle residue depleted of diisocyanate, which is solid at room temperature.

Abstract: The present invention relates to a process for preparing a low boiling monoisocyanate having a boiling point of between 70 and 320° C. at standard pressure by reacting A) a high boiling isocyanate compound having a boiling point of at least 180° C. at standard pressure and an HC content of at least 50 ppm with B) a monoamine having a primary amino group, at a maximum reaction temperature of 180° C. and a molar ratio of isocyanate groups to amino groups of at least 4:1 to form a compound containing a biuret/urea group, simultaneously thermally decomposing this compound in situ to form a monoisocyanate corresponding to monoamine B) and removing the monoisocyanate by distillation, optionally under vacuum.