Abstract: The present invention relates to a method of producing a rigid polyurethane foam in which a polyisocyanate containing a benzene ring is used as an organic isocyanate and a polyether polyol and/or polyester polyol is used as a polyol, characterized in that a hydrocarbon is used as the blowing agent and a compound having a hydrophobic group and a hydroxyl group in the molecule is used as an emulsifying agent. The blowing agent is preferably a hydrocarbon selected from the group consisting of cyclopentane, n-pentane and iso-pentane.

Abstract: A method for preventing the coloration of a diphenylmethane diisocyanate compound, which comprises adding, to the diphenylmethane diisocyanate compound, a hindered amine compound of the formula: ##STR1## wherein R.sup.1 and R.sup.3 are, the same or different, each a hydrogen atom or a C.sub.1 -C.sub.8 hydrocarbon group,R.sup.2 and R.sup.4 are, the same or different, each a C.sub.1 -C.sub.8 hydrocarbon group,R.sup.5 is a hydrogen atom, a methyl group, an ethyl group, a phenoxymethyl group or a phenyl group, andm is 0, 1 or 2,in an amount of 0.001 to 1.0 parts by weight per 100 parts by weight of the diphenylmethane diisocyanate compound.An excellent effect of preventing the coloration can be achieved only by the addition of a small amount of the hindered amine compound of the formula (I).

Abstract: A method for preventing coloration of an aromatic isocyanate compound, which is characterized in that an organic phosphite ester of formula: ##STR1## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are, the same or different, each a C.sub.4-20 hydrocarbon group, 2,6-di-tert.-butyl-4-methylphenol and triphenyl phosphite are added to the aromatic isocyanate compound.

Abstract: A polyol composition with a viscosity at 25.degree. C. of not higher than 50,000 cps which comprises (1) 100 parts by weight of a polyether polyol with a molecular weight of 2,000 to 10,000 prepared by addition of ethylene oxide and propylene oxide to a di- or tri-functional compound containing active hydrogen atoms, (2) 5 to 30 parts by weight of an aromatic diamine, (3) a solution of 0.5 to 5 parts by weight of fatty acid metal salt in an aliphatic amine and (4) 10 to 50 parts by weight of a potassium titanate needle crystal, which has low viscosity and can be easily handled in a molding step.

Abstract: Rigid polyurethane foams are obtained by reacting an isocyanate-reactive component containing at least two isocyanate-reactive hydrogen atoms, having a molecular weight of from 32 to 10,000 or a mixture thereof, with a polyisocyanate composition comprising(a) 30 to 70 pbw of polymethylene polyphenyl polyisocyanate with an iscocyanate content of from 29 to 32%,(b) 30 to 70 pbw of a compound having 30 to 42% by weight isocyanate content obtained by reacting 2,4- and/or 2,6-tolylene diisocyanate with an active hydrogen containing compound, thereafter initiating a reaction in the presence of trimerization catalyst, if necessary diluted with 2,4- and/or 2,6-tolylene diisocyanate,(c) 0 to 30 pbw of other isocyanate compounds in the presence of water and/or organic blowing agents, catalysts and surfactants.

Abstract: A novel magnetic recording medium consisting of a base material, magnetic particles and a specific polyurethane-based binder containing incorporated sulphonate groups, a process for preparing such a magnetic recording medium which comprises coating a base material with a coating material comprising (i) an organic solvent, (ii) a polyurethane binder containing chemically incorporated sulphonate groups and (iii) magnetic particles and the most preferred binder composition therefor comprising a hexandiol-(1,6)-polycarbonate-based polyurethane.

Abstract: The present invention provides a process for purifying an organic isocyanate which comprises heating an organic isocyanate in admixture with a treating agent selected from the group consisting of a metal salt of mercaptobenzothiazol, a dithiocarbamic acid derivative, an alkyl-substituted phenol, a thio-bisphenol, and a triaryl phosphite at a temperature not lower than 100.degree. C and subsequently distilling the thusly treated mixture to recover a purified organic isocyanate.