- PROCESS FOR PREPARING AROMATIC ISOCYANATES
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The invention relates to a process for preparing isocyanates by reacting the corresponding amines with phosgene in the liquid phase, if appropriate in the presence of at least one inert medium, in which the amine and the phosgene are first mixed in a mixing chamber (1) to give a reaction mixture and the reaction mixture is fed to a reactor, the amine being added through an orifice (3) arranged coaxially to the mixing chamber (1) and the phosgene being added through feed orifices (5) in at least two planes (7, 9) arranged at right angles to the axis (11) of the mixing chamber (1), or the phosgene being added through the orifice (3) arranged coaxially to the mixing chamber and the amine through the feed orifices (5) in at least two planes (7, 9) arranged at right angles to the axis (11) of the mixing chamber (1). At least one plane (9) is arranged upstream and at least one plane (7) downstream of the orifice (3) arranged coaxially to the mixing chamber (1) in main flow direction of the reaction mixture. The mean residence time of the reaction mixture in the mixing chamber (1) is not more than 20 ms.
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Page/Page column 4
(2011/10/19)
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- Process for the production of 4,4'-diphenylmethane diisocyanate
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The present invention relates to a process for the production of 4,4′-diphenylmethane diisocyanate (4,4′-MDI) by acid-catalyzed condensation of aniline with formaldehyde, reaction of the mixtures of di- and polyamines obtained with phosgene to form the corresponding mixture of MDI isomers and homologues (di- and polyisocyanates of the diphenylmethane series) and subsequent separation of the mixture by distillation to form 4,4′-MDI and polymeric MDI.
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Page/Page column 3-4
(2008/06/13)
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- Process for the production of isocyanates
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Isocyanates, preferably diisocyanates and polyisocyanates of the diphenylmethane series (MDI), are produced by reaction of amines dissolved in a solvent with phosgene in the same solvent to form the corresponding isocyanates. Hydrogen chloride and excess phosgene are subsequently removed from the reaction mixture to obtain a crude isocyanate-containing solution. Subsequently, the crude isocyanate-containing solution is separated by distillation into isocyanates and solvent. The solvent is recycled and used for the production of solutions of the amines and of phosgene. The solvent being recycled is treated to reduce the phosgene and diisocyanate contents before being used for the production of the solution of the amine.
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Page/Page column 4-5
(2008/06/13)
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- Process for the preparation of 4,4'-diphenylmethane diisocyanate
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4,4'-diphenylmethane diisocyanate is produced at two different sites by a) reacting aniline and formaldehyde in the presence of an acid catalyst to produce a mixture of diamines and polyamines of the diphenylmethane series at a first production site, b) these diamines and polyamines are then reacted with phosgene to give the corresponding diisocyanates and polyisocyanates of the diphenylmethane series, which may optionally be separated by distillation to give a mixture of diisocyanates and polyisocyanates containing from 50 to 80 wt.% of 4,4'-diphenylmethane diisocyanate, from 1 to 12 wt.% of 2,4'- and/or 2,2'-diphenylmethane diisocyanate taken together, and from 10 to 45 wt.% of trifunctional and higher-functional polyisocyanates, based on the weight of the mixture of diisocyanates and polyisocyanates, c) transferring the mixture of diisocyanates and polyisocyanates to transport containers and transporting these isocyanate-containing containers to a second production site remote from the first, and d) separating the mixture of diisocyanates and polyisocyanates by distillation and/or crystallization to give a pure 4,4'-diphenylmethane diisocyanate containing at least 97 wt.% of 4,4'-diphenylmethane diisocyanate and a maximum of 3 wt.% of 2,4'-diphenylmethane diisocyanate.
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Page/Page column 5-6
(2008/06/13)
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- Process for distilling a mixture of isomeric diisocyanatodiphenylmethanes
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Preparation of 2,4'-methylene diphenylene diisocyanate (MDI) comprises distillation of a diisocyanatodiphenylmethane isomer mixture from 2,2'-diisocyanatodiphenylmethane, 2,4'-diisocyanatodiphenylmethane and 4,4'-diisocyanatodiphenylmethane to give a mixture comprising 2,4'-diisocyanatodiphenylmethane (85-99 wt.%), 4,4'-diisocyanatodiphenylmethane (up to 15 wt.%) and 2.2'-diisocyanatodiphenylmethane (up to 0.2 wt.%). Preparation of 2,4'-methylene diphenylene diisocyanate (MDI) (with less production of 2,4'-MDI) comprises distillation of a diisocyanatodiphenylmethane isomer mixture from 2,2'-diisocyanatodiphenylmethane, 2,4'-diisocyanatodiphenylmethane and 4,4'-diisocyanatodiphenylmethane to give a mixture comprising 2,4'-diisocyanatodiphenylmethane (85-99 wt.%), 4,4'-diisocyanatodiphenylmethane (up to 15 wt.%) and 2.2'-diisocyanatodiphenylmethane (up to 0.2 wt.%) (where: distillation is carried out in a single-step; a partition column is used in at least one distillation stage; a destillative before separation is upstreamed to the partition column before distillation to give a mixture (comprising 2,2'-diisocyanatodiphenylmethane (0-15 wt.%), 2,4'-diisocyanatodiphenylmethane (12-60 wt.%) and 4,4'-diisocyanatodiphenylmethane (25-88 wt.%)), which is used as feed stream to the partition column; and the vapor at the top of the partition column is condensed and 98-99.6% of it returns to the top zone).
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Page/Page column 5-6
(2008/06/13)
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- Process for the preparation of mixtures of di- and polyisocyanates of the diphenylmethane series with a high amount of 4,4'-methylenediphenyldiisocyanate and 2,4'-methylenediphenyldiisocyanate
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A fraction of diisocyanates of the diphenylmethane series is produced by reacting aniline and formaldehyde in the presence of an acid catalyst; phosgenating diamines and polyamines of diphenylmethane series containing binuclear methylenediphenyl diamine to produce a crude diisocyanate and polyisocyanate; and separating from crude diisocyanate and polyisocyanate, a fraction containing >=95 wt.% binuclear methylenediphenyl diisocyanate. Production of a fraction of diisocyanates of the diphenylmethane series containing >=95 wt.% binuclear methylenediphenyl diisocyanate by: (1) reacting aniline and formaldehyde in the presence of an acid catalyst to produce diamines and polyamines of the diphenylmethane series containing binuclear methylenediphenyl diamine; (2) phosgenating the diamines and polyamines of the diphenylmethane series containing binuclear methylenediphenyl diamine to produce a crude diisocyanate and polyisocyanate; and (3) separating from the crude diisocyanate and polyisocyanate, a fraction containing >=95 wt.% binuclear methylenediphenyl diisocyanate comprising greater than 60 wt.% 4,4'-methyl diisocyanate (MDI), 4-35 wt.% 2,4'-MDI, 0.01-10 wt.% 2,2'-MDI relative to the mass of the fraction; and not >20 ppm phenyl isocyanate in a single distillation step. Independent claims are also included for: (1) production of a diphenylmethane diisocyanate mixture comprising blending the separated fraction with a mixture containing an aromatic isocyanate; and (2) production of a polymer comprising reacting the separated fraction and/or the blend of separated fraction with a mixture containing an aromatic isocyanate with a polyol.
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Page/Page column 8
(2008/06/13)
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- METHOD FOR PRODUCING VERY PURE 2,4'-METHYLENE DIPHENYL DIISOCYANATE
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PROBLEM TO BE SOLVED: To produce a mixture of methylene diphenyl diisocyanate (MDI) isomers having a high 2,4'-MDI content, while being decreased in amounts of components, such as 2,2'-MDI, a residual solvent, and phenyl isocyanate, to such an extent as not to disturb production of a polyurethane. SOLUTION: In a method for producing a fraction of diphenylmethane-based diisocyanates, the fraction contains at least binuclear methylene diphenyl diisocyanates in an amount of at least 99 wt% based on a total amount of the fraction.
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Page/Page column 14
(2008/06/13)
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