Abstract:
Gegenstand der Erfindung ist ein Verfahren zur Herstellung von Mischungen aus Diphenylmethan-diisocyanaten und Polyphenyl-polymethylen-polyisocyanaten (Roh-MDI) mit einer verminderten Iodfarbzahl und einem verminderten Chlorgehalt durch Umsetzung der entsprechenden Mischungen aus Diphenylmethan-diaminen und Polyphenyl-polymethylen-polyaminen mit Phosgen in Gegenwart mindestens eines inerten organischen Lösungsmittels bei erhöhter Temperatur, wobei man nach beendeter Phosgenierung der Reaktionsmischung in Gegenwart oder Abwesenheit des Phosgens eine Mischung aus Wasser und mindestens einem ein- oder mehrwertigen Polyoxyalkylenalkohol, vorzugsweise mit einer Funktionalität von 2 bis 3, und vorteilhafterweise einer Hydroxylzahl von 20 bis 1800, in einer wirksamen Menge, die zweckmäßigerweise besteht aus mehr als 0,01 bis 0,3 Gew.-% Wasser (i) und 0,5 bis 5 Gew.-% eines Polyoxyalkylenalkohols (ii), jeweils bezogen auf das Roh-MDI-Gewicht, einverleibt, danach das überschüssige Phosgen bzw. die noch vorliegenden Phosgenreste und das inerte organische Lösungsmittel abtrennt, dem Reaktionsprodukt gegebenenfalls bis 5 Gew.-%, bezogen auf das Roh-MDI-Gewicht, mindestens eines Antioxidans auf Phenolbasis und/oder Arylphosphit hinzugefügt und die Reaktionsmischung thermisch behandelt.
Abstract:
The invention relates to a process for the preparation of polyisocyanates containing uretdione groups by catalytic dimerisation of monomeric isocyanates, polymers bearing imidazole groups being employed as catalysts.
Abstract:
The invention relates to a process for the preparation of mixtures of diphenylmethane diisocyanates and polyphenylpolymethylene polyisocyanates (crude MDI) having a reduced iodine colour value by reaction of corresponding mixtures of diphenylmethanediamines and polyphenylpolymethylenepolyamines with phosgene in the presence of at least one inert organic solvent at elevated temperature, in which, after phosgenation of the reaction mixture is complete, low-molecular-weight alkanols, polyhydric alcohols, preferably di- to octahydric alcohols having a molecular weight of 60 to 350, or mixtures thereof are incorporated in an effective amount, advantageously in an amount of 0.01 to 5% by weight, relative to the crude MDI weight, the phosgene and the inert organic solvent are then separated off, 0 to 5% by weight, relative to the crude MDI weight, of at least one phenol-based antioxidant and/or aryl phosphite are added to the reaction product, and the reaction mixture is subjected to a heat treatment.
Abstract:
The invention relates to a process for the preparation of mixtures of diphenylmethane diisocyanates and polyphenylpolymethylene polyisocyanates (crude MDI) having a reduced iodine colour value by reacting the corresponding mixtures of diphenylmethanediamines and polyphenylpolymethylenepolyamines with phosgene in the presence of at least one inert organic solvent at an elevated temperature, wherein, after the end of the phosgenation, at least one monohydric or polyhydric polyoxyalkylene alcohol, preferably having a functionality of 2 to 3, and advantageously having a hydroxyl number of 20 to 1,800, or a mixture thereof is incorporated into the reaction mixture in an effective amount, advantageously in an amount of 0.1 to 10% by weight, based on the weight of the crude MDI, the phosgene and the inert organic solvent are then separated off, optionally up to 5% by weight, based on the weight of the crude MDI, of at least one phenol-based antioxidant and/or aryl phosphite are added to the reaction product and the reaction mixture is subjected to a thermal treatment.
Abstract:
The invention relates to novel 4,4'-disubstituted bis(2,6-diisopropylphenyl)carbodiimides of the formula (I) in which R is a 1-methyl-1-phenylethyl, phenoxy or tert-butyl radical, to a process for their preparation and to their use as stabilisers with respect to the hydrolytic degradation of ester group-containing products of addition and condensation polymerisation, and to the novel compounds which can be used to prepare them, namely 4-(1-methyl-1-phenylethyl)-2,6-diisopropylphenyl, 4-phenoxy-2,6-diisopropylphenyl and 4-tert-butyl-2,6-diisopropylphenyl isocyanates.
Abstract:
Prodn. of mixts. (I) of diphenylmethane diisocyanates (MDI) and polyphenyl polymethylene polyisocyanates (IA) with reduced I2 colour no. involves reacting corresp. mixts. (II) of diphenylmethane diamines (MDA) and polyphenyl polymethylene polyamines (IIA) with COCl2 in the presence of inert organic solvent(s) (III) at elevated temp., sepn. of excess COCl2 and (III) when phosgenation is complete and thermal treatment of the reaction prod. The novelty is that amines (IVA) and/or urea cpds. (IVB) are incorporated in the reaction mixt. after phosgenation. (IVA) are aromatic amines, pref. MDA and/or (IIA); and (IVB) are aliphatic and/or aromatic cpds., pref. urea derivs. of MDI and/or (IA). (IV) are added in amts. of 0.01-2.5% w.r.t. (I) in the reaction mixt. and at the time when the COCl2 content of the mixt. is 0.01-3%. USE/ADVANTAGE - (I) are useful in the prodn. of compact or foamed polyisocyanate poly-addn. prods., pref. flexible or (semi-)rigid foam contg. urethane and opt. isocyanurate gps. Addn. of (IV) reduces I2 colour no., e.g. to under 60, without the need to add water. The (I) obtd. contain 30-90, pref. 30-70 (wt.)% MDI isomers and have an NCO content of 31 +/- 2, pref. 31 +/- 1% and viscosity of max. 2000, pref. 40-700 mPa.s at 23 deg.C. (I) give light-coloured foams.
Abstract:
Prepn. of mixts. comprising diphenylmethane dissocyanates and polyphenyl-polymethylene -polyisocyanates having a reduced iodine dye number, includes preparing the mixts. by usual methods, then sepg. excess phosgene and solvent and then treating the mixt. with radical forming azo cpds. (A). Pref. the decomposition temp. of (A) is 20-150 (50-100) deg. C Pref. 500-3000ppm (w.r.t. wt. of mixt.) (A) are added to the mixt. The temp. for the (A) treatment is pref. greater than the decompositon temp. for (A), and the treatment is pref. continued until nitrogen is not longer liberated. USE/ADVANTAGE - The obtd. mixts. are useful as starting prods. for the prepn. of polyisocyanate polyaddition prod-contg. foams and 4,4'-diphenylmethane diisocyanate, useful for the prepn. of polyurethane elastomers, fibres adhesives etc. The iodine dye number is reduced without a deterioration of the remaining properties of the mixt.
Abstract:
Oligomeric carbodiimides having an average degree of condensation of from 2 to 30, obtainable by oligocondensation of a) from 40 to 100 mol % of 2,4'-diisocyanatodiphenylmethane or of a 3,3',5,5'-tetra-C1-C4-alkyl-4,4'-diisocyanatodiphenylmethane and b) from 0 to 60 mol % of a further bi- or polyfunctional aromatic isocyanate and c) if desired, complete or partial reaction of the remaining free isocyanate groups of the oligomers with an aliphatic, araliphatic or cycloaliphatic alcohol or amine, are used mainly for stabilizing polyester-containing polyurethanes against hydrolytic degradation.
Abstract:
Mixt (I) of diphenylmethane di-isocyanates and polyphenylpolymethylene polyisocyanates is pred by, (1) reacting corresp mixt of diphenylmethane diamines and polyphenylpolymethylene polyamines with phosgene (II) in presence of at least one inert organic solvent at raised temp, (2) after phosgenation has finished, incorporating effective amt of phosphite (III) which is a tri-and/or di-alkyl phosphite, (3) removing excess (II) and solvent, and (4) heating reaction mixt. USE/ADVANTAGE - For use in prodn of compact or foamed polyisocyanate polyaddn prods, partic flexible semihard or hard foams contg urethane and opt isocyanurate gps, having lighter colour. (I) having reduced iodine colour is obtd without addn of small proportion of water after phosgenation but before complete sepn of (II) (US4465639), which promotes corrosive effect of C12, HCl and (II) on appts and causes risk of leak of (II) or (II)-contg reaction mixt.