Abstract: Process for the purification of toluenediisocyanate from a crude distillation feed comprising toluenediisocyanate, an organic solvent and less than 2% by weight phosgene by separating the crude distillation feed in a dividing-wall distillation column into at least four product fractions P1-P4.

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.

Abstract: Polyisocyanates of the diphenyl methane series having reduced color values are obtained by a) reacting aniline and formaldehyde in the presence of an acid catalyst to form a polyamine, b) neutralizing the reaction mixture containing polyamine with a base, c) separating the neutralized mixture into the aqueous and the organic phases, d) adding a base to the organic phase and then e) phosgenating the resulting polyamine to produce the corresponding polyisocyanate.

Abstract: In a process for preparing mixtures of diphenylmethane diisocyanates and polyphenylpolymethylene polyisocyanates having a reduced content of chlorinated by-products and a reduced iodine color number by two-stage reaction of the corresponding mixtures of diphenylmethanediamines and polyphenylpolymethylenepolyamines with phosgene in the presence of at least one inert organic solvent at elevated temperature, separation of the excess phosgene and solvent after the phosgenation is complete and thermal treatment of the reaction product, the mass ratios of phosgene to hydrogen chloride in the residence time apparatus of the second stage of the phosgenation are at the same time 10-30:1 in the liquid phase and 1-10:1 in the gas phase.

Abstract: The invention provides a process for reducing the amount of monomeric polyisocyanate in a composition comprising a polymer or oligomer bearing isocyanate groups, the method comprising reacting the composition with a quenching agent, the quenching agent comprising an arylalkyl alcohol and an alkoxysilane bearing a secondary amino group.

Abstract: The invention is directed to polyurethane prepolymers having a reduced amount of unreacted monomeric diisocyanate, particularly diphenylmethane diisocyanate (MDI), prepared by distilling the prepolymer reaction product in the presence of at least one inert solvent whose boiling point is slightly below that of the monomeric diisocyanate; and to high performance cast polyurethane elastomers from the thus obtained prepolymers using diamine and/or diol chain extenders.

Abstract: The invention provides a new process for purifying organic isocyanates or isocyanate mixtures by mixing the isocyanates or isocyanate mixtures to be purified with at least one alcohol and/or thiol or a mixture of alcohols and/or thiols, heating the resultant mixture and simultaneously or subsequently degassing the mixture and/or working up the mixture by distillation and/or extraction.

Abstract: An organic isocyanate or mixture of isocyanates is treated with at least one high molecular weight ester of phosphoric acid corresponding to a specified formula to remove chlorine compounds. The isocyanates which are purified in this manner are useful for the production of coatings, polyurethane moldings and chemical intermediates.

Abstract: A process is described for obtaining pure isocyanate isomers from a mixture of isocyanate isomers by suspension crystallization and the isolation of isomerically pure crystals, which is characterized in that, prior to the isolation of the crystals, 5 to 40% by weight of the crystals produced are remelted while simultaneously increasing the temperature of the crystal slurry by 4.5 to 9° C.

Abstract: Mixtures of diphenylmethane diisocyanates and polyphenylpolymethylene polyisocyanates (raw MDI) having a reduced iodine color number and a reduced chlorine content are prepared by reacting the corresponding mixtures of diphenylmethanediamines and polyphenylpolymethylenepolyamines with phosgene in the presence of at least one inert organic solvent at elevated temperature, and then, after phosgenation is complete, incorporating into the reaction mixture, in the presence or absence of the phosgene, a mixture of water and at least one monohydric or polyhydric polyoxyalkylene alcohol, preferably having a functionality of from 2 to 3, and advantageously having a hydroxyl number of from 20 to 1800, in an effective amount which advantageously comprises from more than 0.01 to 0.3% by weight of water (i) and from 0.

Abstract: A process for the purification of organic isocyanates or isocyanate mixtures in which the amount of chlorine compound(s) present is reduced by mixing the isocyanate(s) or isocyanate mixtures with a gel-type or macroporous, anion-exchanging organic material having tertiary and/or quaternary amino groups. The process renders possible a purification of the isocyanates from chlorine-containing compounds which is milder than in conventional processes and is therefore particularly suitable for temperature-sensitive isocyanates.

Abstract: Isocyanates or isocyanate mixtures which are substantially free of color-imparting components are made by treating the isocyanate with hydrogen in the presence of a catalyst at a pressure of from about 3 to about 150 bar, a temperature of from about 100 to about 180.degree. C. for from about 15 minutes to about 4 hours. These isocyanates are particularly useful for the preparation of light-colored polyurethane rigid foams.

Abstract: The present invention relates to a process for isolating aliphatic isocyanate monomer(s) from a liquid or viscous paste composition comprising polymeric isocyanate residues and the aliphatic isocyanate monomer(s), and for isolating solid polymeric isocyanate residue from said composition. Also disclosed is the aliphatic isocyanate monomer(s) and the solid polymeric isocyanate byproduct produced by this process.

Abstract: Disclosed herein is an improved process for preparing a polyamine mixture derived by reacting aniline with formaldehyde in the presence of an acid catalyst the improvement comprising mildly reducing the polyamine mixture by a process step comprising catalytically or chemically hydrogenating the polyamine mixture in the presence of a metal catalyst.

Abstract: A process is described for the separation and recovery of isocyanate monomers from isocyanate concentrates which leaves a residue which is liquid and burnable. The process for the separation and recovery of isocyanate monomers from isocyanate concentrates formed in the production of isocyanates and comprising a volatile isocyanate monomer and by-products comprises the steps of:(A) preparing a mixture comprising(A-1) the isocyanate concentrate; and(A-2) an oil solution comprising;(A-2-a) a major amount of hydrocarbon oil, and(A-2-b) a minor amount of at least one ashless dispersant; and(B) heating the mixture to an elevated temperature at reduced pressure whereby isocyanate monomer is distilled and recovered leaving a liquid residue.

Abstract: A method for obtaining substantially pure toluylene 2,6-diisocyanate from a mixture of the 2,4 and 2,6 isomers of toluylene diisocyanate, wherein at least one crystallizing-melting cycle is performed on the mixture of said isomers to separate out the toluylene 2,6 diisocyanate isomer. In an alternative embodiment, the mixture is contacted, prior to the crystallizing-melting cycle, with a compound or catalyst capable of converting part of the toluene 2,4-diisocyanate isomer therein, and the reacted 2,4 isomer is separated. Said method is advantageous in that usable by-products are produced.

Abstract: The present invention relates to a process for preparing pure bis(isocyanatoalkyl)monouretdiones corresponding to formula (I) ##STR1## wherein R represents identical or different, linear or branched alkyl groups having 4 to 9 carbon atoms,by oligomerizing at least a portion of the isocyanate groups of aliphatic diisocyanates in the presence of catalysts which accelerate the dimerization of isocyanate groups, terminating the reaction at the desired degree of oligomerization, removing unreacted excess diisocyanate by extraction or thin film distillation to obtain a distillation residue, subjecting the distillation residue to thin film distillation at a temperature of 160.degree. to 220.degree. C. and a pressure of 0.01 to 1.0 mbar and obtaining bis(isocyanato-alkyl)monouretdiones corresponding to formula (I) as the distillate.

Abstract: A process for reducing the amount of residual organic diisocyanate monomer in a polyurethane prepolymer reaction product mixture which comprises distilling the polyurethane prepolymer reaction product mixture in the presence of a combination of at least one inert first solvent with a boiling point below the boiling point of the residual organic diisocyanate monomer and at least one inert second solvent with a boiling point above the boiling point of the residual organic diisocyanate monomer, at a temperature which exceeds the vaporization temperature of the residual organic diisocyanate monomer and which is below the decomposition temperature of the polyurethane prepolymer.

Abstract: The present invention relates to a polyisocyanates containing allophanate groups and optionally isocyanurate groups that are prepared by reacting compounds whichi) are substantially free of hydroxyl groups and isocyanate groups,ii) have an average of at least two urethane groups per molecule andiii) are the reaction products of linear or branched, aliphatic isocyanates with organic hydroxyl compounds,with an excess quantity, based on the urethane groups, of 4,4'-bis-(isocyanatocyclohexyl)-methane to form polyisocyanates containing allophanate groups and optionally isocyanurate groups and optionally removing at least a portion of the unreacted excess 4,4'-bis-(isocyanatocyclohexyl)-methane. The present invention also relates to a process for the production of these polyisocyanates and to their use as binders or binder components in coating compositions.

Abstract: A process for preparing isocyanates comprising contacting carbon dioxide and a primary amine in the presence of an aprotic organic solvent and a base selected from the group consisting of a phosphazene compound, an organic, nitrogenous base and mixtures thereof, wherein the organic, nitrogenous base selected from the group consisting of guanidine compounds, amidine compounds, tertiary amines and mixtures thereof to produce the corresponding ammonium carbamate salt, reacting the ammonium carbamate salt with an anhydride dehydrating agent to produce a product stream comprising the corresponding isocyanate, the aprotic organic solvent and the base salt derived from the anhydride, separating the base salt from the product stream, recovering and recycling the base, and regenerating and recycling the anhydride dehydrating agent.

Abstract: Pure isocyanate is recovered from an isocyanate-containing residue of a phosgene/amine reaction mixture by continuously feeding such residue and a high boiling hydrocarbon such as bitumen to a heated vacuum drier with a horizontal shaft. The contents of the drier are subjected to temperatures of from about 160.degree. to about 280.degree. C. and pressures of from about 2 to about 50 mbar. Pure isocyanate and a pourable, non-dusting, granular material are recovered.

Abstract: A process for the purification of organic polyisocyanates by mixing of the polyisocyanate with from 0.001 to 1% by weight of compounds containing trimethylsilyl groups at temperatures of from 20.degree. to 150.degree. C. The resultant mixture of organic polyisocyanates and compounds containing trimethylsilyl groups is optionally treated by degasification or distillation. These purified polyisocyanates are suitable for the production of polyurethane plastics, and in particular, polyurethane foams.

Abstract: The hue of a methylene-crosslinked polyphenylene polyisocyanate continuously produced by the reaction with phosgene in an inert solvent of a polyamine mixture obtained by condensation of aniline and formaldehyde in the presence of an acid catalyst is improved by first removing any residual phosgene followed by heat treatment in the presence of hydrogen chloride gas.

Abstract: A process for the production of pure distilled isocyanates in which the corresponding amine is reacted with phosgene in a suitable solvent and working up of the isocyanate containing solution obtained by multistage distillation into pure isocyanate, pure solvent and a residue. The residue is then charged to a vessel containing at least one hydrocarbon having a high boiling point. The contents of this vessel are then heated with stirring to distill off any free isocyanate present. The remaining residue is a solid which may be disposed of readily.

Abstract: Disclosed herein is a process for recovering toluene diisocyanate (TDI) from a TDI residue solution, comprising mixing the residue solution with a polyisocyanate consisting essentially of methylenediphenyl diisocyanate (MDI) or MDI in combination with its higher ring oligomer, followed by heating the resulting mixture over a temperature range of 130.degree. to 250.degree. C. for a period of time sufficient to remove free TDI and thermally splittable TDI generated from equilibration of the TDI residue with MDI or the MDI oligomer by either a batch or continuous process.

Abstract: A process for recovering a distillate of tolylene diisocyanate and an isocyanate-group-containing sump product containing less than 200 ppm (by weight) tolylene diisocyanate from A) distillation residues obtained in the production of tolylene diisocyanate by mixing of the distillation residues A) with B) optionally urethane- and/or allophanate-modified polyisocyanates or polyisocyanate mixtures of the diphenyl methane series, heating of the mixture to 190.degree. to 250.degree. C. and simultaneously or subsequently working up by distillation.

Abstract: The present invention is directed to a process for the production of polymethylene polyphenyl polyisocyanates by phosgenating the corresponding polyamines in solution in an inert organic solvent, removing excess phosgene, and stripping the solvent. The improvement resides in adding at least 0.02 parts by weight of reducing agent per 150 parts by weight of polyamine to the polyamines at any time prior to the stripping step.

Abstract: Polyisocyanate mixtures are isolated in pure or more concentrated form from isomeric mixtures by liquid-liquid extraction using a two-phase system. The two phases are 1) a non-polar solvent phase and 2) a polar solution in which a hydrogen halide is present. In a preferred embodiment, the extraction is carried out in a countercurrent extractor.

Abstract: This invention relates to a multi-step process for isolating a cyclotrimerized isocyanate from mixture containing said cyclotrimerized isocyanate plus an isocyanate oligomer which comprises the steps of: (a) contacting said mixture with a liquid solvent to provide a solvent-containing mixture, (b) extracting said solvent-containing mixture by liquid-liquid extraction to cause said solvent-containing mixture to elute into an extractate and a residue, wherein said extractate is a cyclotrimerized isocyanate that is essentially oligomer-free and is further characterized by having reduced viscosity relative to said solvent-containing mixture, and (c) separating uncyclotrimerized monomer from said extractate to provide a reduced viscosity trimer product that is essentially free of monomer. Also disclosed is the reduced-viscosity product produced by this process.

Abstract: A process for the continuous catalyst-free production of polyisocyanates by thermal decomposition of the N-substituted carbamic acid esters corresponding to the polyisocyanates, in which the carbamic acid esters to be decomposed, in the form of a 5 to 90% by weight solution in an inert high-boiling solvent, are heated to a temperature of 100.degree. to 400.degree. C. and are subsequently introduced with expansion as a sidestream into a distillation column (4), in the sump of which a pressure of 0.001 to 5 bar and a temperature of 150.degree. to 400.degree. C. are maintained so that the high boiler is kept boiling in the sump, and the decomposition products are simultaneously condensed continuously and selectively at the head of the distillation column. The high boiler, which optionally contains impurities, is continuously removed via the sump outlet in a quantity substantially corresponding to the quantity of high boiler introduced into the column as solvent for the carbamic acid ester.

Abstract: The present invention relates to a process for the conditioning and/or purification of organic isocyanates bya) mixing organic isocyanates at 20.degree. to 150.degree. C. with 0.001 to 1 mole %, based on the isocyanate, of a silylated acid corresponding to the formulaX-[Si(CH.sub.3).sub.3 ].sub.nwhereinX represents the neutral acid residue obtained by removing the acidic hydrogen atoms from an n-basic acid having a pKa value of at most 3, with the exception of hydrohalic acids andn is an integer from 1 to 3, andb) optionally working up the resulting mixture by distillation after a residence time of at least 5 minutes.

Abstract: Disclosed herein is a free-flowing solid of 4,4'-diisocyanato dicyclohexylmethane consisting essentially of at least 90 percent of the trans,trans isomer.

Abstract: Mixtures of diphenylmethane diisocyanates and polyphenylpolymethylene polyisocyanates (crude MDI) of reduced iodine color number are prepared by reacting the corresponding mixtures of diphenylmethanediamines and polyphenylpolymethylenepolyamines with phosgene in the presence of at least one inert organic solvent at elevated temperature, at least one monohydric or polyhydric polyoxyalkylene alcohol, preferably having a functionality of from 2 to 3, and advantageously having a hydroxyl number of from 20 to 1800, or mixtures thereof in an effective amount, expediently in an amount of from 0.1 to 10% by weight, based on the weight of the crude MDI, being introduced into the reaction mixture when the phosgenation is complete, the phosgene and the inert organic solvent then being removed, up to 5% by weight, based on the weight of crude MDI, of at least one phenol-based antioxidant and/or aryl phosphite being added, if desired to the reaction product, and the reaction mixture being heated.

Abstract: A wiped film evaporation process for reducing the amount of residual organic polyisocyanate, especially toluene diisocyanate, in a polyurethane prepolymer reaction product mixture. An inert sweeping gas is added to the evaporation process, preferably after first passing through a holdup volume of the prepolymer which has passed through the evaporation zone.

Abstract: Disclosed is a method for reducing hydrolyzable chloride in toluene diisocyanate (TDI) and, particularly, in TDI distillation bottoms, and polymers produced using the reduced hydrolyzable chloride bottoms. Crude TDI is heated, optionally in the presence of a solvent, to cause: (a) partial reflux, (b) partial reflux and fractionation, or (c) complete reflux and fractionation; under conditions sufficient to reduce hydrolyzable chloride. After distilling the crude TDI to form TDI monomer, the bottoms produced are thereby desirably reactive and viscosity-stable over a significant period of time. The treated bottoms can be reacted with compounds containing active hydrogen containing groups to form polyurethane, polyurea, and polyisocyanurate polymers, particularly foams.

Abstract: A fractionation process of a methylene bridged polyphenylene polyisocyanate mixture obtained by phosgenating condensation product of aniline and formaldehyde is disclosed.In order to apply the above mixture to a variety of uses, the process separates the mixture into fractions by giving primary attention to the content of 4,4'-and 2,4'-isomer of diphenylmethane diisocyanate and at the same time reduces the content of impurities having acidity and hydrolyzable chlorine.

Abstract: The present invention is directed for preparing a 4,4'-diisocyanato dicyclohexylmethane which contain a relatively high amount of the trans,trans-isomer. The process broadly comprises (a) melting a mixture of 4,4'-diisocyanato dicyclohexyl-methane isomers, (b) cooling the melted mixture to form: (1) a liquid phase and (2) a solid phase, (c) removing said liquid phase, which is a commercially viable product itself, (d) heating the solid phase and removing that portion of the solid phase which has melted, and (e) recovering that portion of said solid phase which has not melted by heating the remaining portion.

Abstract: Disclosed herein is an improved process for the preparation of polymethylene polyphenyl polyisocyanate by reacting phosgene with a corresponding polyamine, followed by removing residual phosgene from the reaction mixture, the improvement comprising removing the residual phosgene by contacting the reaction mixture which is maintained at 150 degrees Centigrade or lower, with an inert solvent vapor stream at a temperature which is sufficient to effect a substantially complete removal of the residual phosgene.

Abstract: A wiped film evaporation process for reducing the amount of residual toluene diisocyanate in a polyurethane prepolymer reaction product mixture. An inert sweeping gas is added to the evaporation process, preferably after first passing through a holdup volume of the prepolymer which has passed through the evaporation zone.

Abstract: A process is described for the separation and recovery of isocyanate monomers from isocyanate concentrates which leaves a residue which is liquid and burnable. The process for the separation and recovery of isocyanate monomers from isocyanate concentrates formed in the production of isocyanates and comprising a volatile isocyanate monomer and by-products comprises the steps of:(A) preparing a mixture comprising(A-1) the isocyanate concentrate; and(A-2) an oil solution comprising;(A-2-a) a major amount of hydrocarbon oil, and(A-2-b) a minor amount of at least one carboxylic ester obtained by reacting(A-2-b-1) at least one substituted succinic acylating agent with(A-2-b-2) at least one alcohol of the general formulaR.sub.3 (OH).sub.M (I)wherein R.sub.

Abstract: This invention is a process for removing volatile impurities from a crude isocyanate compound which is prepared in the phosgenation of a primary amine, comprising heating said crude isocyanate compound to a temperature to volatilize said volatile impurities in the presence of an acidic material containing a plurality of strong acid groups. The process permits faster, more complete removal of hydrolyzable chloride impurities than conventional processes.

Abstract: The present invention is directed to a simple process for preparing a 4,4'-diisocyanato dicyclohexylmethane containing at least 90% by weight of the trans, trans-isomer. More particularly, the process comprises:(a) melting a mixture of 4,4'-diisocyanato dicyclohexylmethane isomers containing at least 30% by weight, and preferably from 45 to 55% by weight, of the trans,trans-isomer,(b) cooling the melted mixture to a temperature of from about 20.degree. to about 25.degree. C.

Abstract: Toluene diisocyanate (TDI) is separated and recovered from the residues of the production thereof, e.g., from the tars of phosgenation of an aromatic diamine, by extracting such residues with an extractant which comprises an inert gas, e.g., CO.sub.2, in either the liquid or supercritical state, optionally in the presence of a coextractant diluent, for example an ester, aromatic hydrocarbon or chlorinated aromatic hydrocarbon, or chlorinated aliphatic hydrocarbon.

Abstract: A method of treating toluene diisocyanate distillation residues comprising reacting the residues with at least about 0.5 equivalents, based on hydrolyzable chloride concentration of the residues, of an epoxy compound at a temperature of from about 155 to about 220.degree. C. to produce a treated distillation residue having a hydrolyzable chloride level of less than about 800 parts per million (ppm) is taught. The product of the method is useful, for instance, in producing rigid foams with low K Factors.

Abstract: The present invention is directed to a process for reducing the free monomer content of polyisocyanate adduct mixtures wherein the adduct has an average isocyanate functionality of greater than about 1.8 which comprises treating the polyisocyanate adduct mixture in the presence of 2 to about 30 percent by weight of an inert solvent, based on the weight of the polyisocyanate mixture, in an agitated thin-layer evaporator under conditions sufficient to reduce the free monomer content of the polyisocyanate adduct mixture below that level which is obtainable in the absence of a solvent.

Abstract: Disclosed is an extraction process wherein a crude polyisocyanate is separated into a purified fraction and residual fraction wherein the purified fraction is characterized by greatly improved color over the crude material but with little or no difference in viscosity. The residual fraction remains perfectly useful for those applications where color is not a critical requirement.Significantly, the disclosed purification is achieved with literally a 100 percent material balance. No loss in polyisocyanate is encountered.

Abstract: Methyl isocyanate can be separated in high yields from a gas-phase mixture of the isocyanate and water by sequentially condensing a major portion of the water, absorbing essentially all the remaining water from the mixture, and liquefying the methyl isocyante.

Abstract: Crude polyisocyanates are purified by extraction at a temperature from 80.degree. to 180.degree. C. to form a two-phase system. The phases are separated and the phase made up of purified polyisocyanate and solvent is cooled to a temperature which is at least 50.degree. C. below the extraction temperature. Upon cooling, a second two-phase system forms. Purified polyisocyanate containing residual solvent is recovered upon separation of these phases. Solvent in which polyisocyanate is present that is reclaimed during this process may be reused in subsequent extractions. The purified polyisocyanates have a viscosity which is lower than that of crude polyisocyanates having substantially the same isocyanate content and average functionality. These purified polyisocyanates are useful in the production of polyurethane foams and moldings as well as adhesives and coatings.

Abstract: Polyisocyanates are produced by reacting a polyamide solution with a phosgene solution. After the product polyisocyanate has been recovered, the solvent or a portion of the solvent employed is treated with crosslinked polymers insoluble in the solvent which polymers contain primary and/or secondary alcoholic hydroxyl groups and/or primary and/or secondary amino groups. After treatment, the polymer and any reaction products are removed. The solvent may then be reused. Preferred solvents are chlorobenzene and o-dichlorobenzene. The preferred polymers are bead polymers or bead copolymers of (meth)acrylic acid or styrene/divinyl benzene copolymer.

Abstract: This invention comprises a process for separating 2,6-toluene diisocyanate from a feed mixture with 2,4-toluene diisocyanate. The process comprises contacting the mixture at adsorption conditions with an adsorbent comprising a Y-type zeolite cation exchanged with a potassium cation, thereby selectively adsorbing the 2,6-toluene diisocyanate. The remainder of the feed mixture is removed from the adsorbent and the adsorbed toluene diisocyanate 2,6-isomer is recovered by desorption at desorption conditions with a desorbent material comprising toluene.