Abstract: The invention relates to a device for the production of granulate grains from a plastic melt, having a nozzle plate with at least one nozzle opening from which a strand of the plastic melt is discharged into a processing chamber, and a cutting tool having at least one cutting blade that may be moved against the nozzle plate by means of a feed device, wherein the plastic strand discharged from the nozzle opening of the nozzle plate can be fragmented into granulate grains by the cutting blade moving relative to the nozzle opening. The nozzle plate has a diamond coating at least on the surface thereof facing the cutting tool, with the hardness of the diamond coating being greater than the hardness of the cutting blade, and with the average roughness of the diamond coating being greater than the average roughness of the cutting blade by at least a factor of two.

Abstract: Polyols are conditioned and stabilized by mixing them at 0 to 150.degree. C. with from about 0.0001 to about 1% by weight, based on the quantity of polyol, of a silylated acid corresponding to the formula:X--[Si(CH.sub.3).sub.3 ].sub.nin whichX represents a neutral acid residue obtained by removal of the acidic hydrogen atoms from an n-basic acid having a maximum pKa value of 3, provided that the n-basic acid is not a hydrohalic acid andn represents an integer of from 1 to 3.The resultant polyol is characterized by good color and activity properties. The stabilized polyols are particularly useful in the production of polyurethanes, particularly polyurethane foams.

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 present invention relates to a process for the preparation of substantially closed-cell rigid foams containing urethane, urea, biuret, and isocyanurate groups comprising reacting, at an index of greater than 110, organic polyisocyanates with relatively high molecular weight polyots consisting of mixtures of (i) polyesters containing at least two hydroxyl groups and having an OH value of greater than 150 and/or polyethers containing at least two hydroxyl groups and having an OH value of greater than 200, and (ii) polyoxyalkylene polyethers containing ethylene oxide residues and least two hydroxyl groups and having an OH value of less than 100, in the presence of isocyanate trimerization catalysts and water as blowing agent. The foams of the invention can optionally be prepared optionally, in the further presence chain-extending and/or crosslinking agents and auxiliaries. and/or additives.

Abstract: The present invention relates to a process for the production of primary amines containing aliphatically or cycloaliphatically bound amino groups, characterized in that the isocyanate groups of organic isocyanates containing aliphatically and/or cycloaliphatically bound isocyanate groups are formylated with formic acid in a first reaction step and the N-formyl groups are subsequently converted into amino groups.The present invention also relates to polyamine mixtures obtained by this process and containinga) about 40 to 90% by weight, based on the total weight of components a) and b), of N,N',N"-tris-(6-aminohexyl)-isocyanurate andb) about 10 to 60% by weight, based on the total weight of components a) and b), of higher homologs of this triamine containing more than one isocyanurate ring.Finally, the present invention relates to the use of these polyamine mixtures as hardeners for polymer precursors containing epoxide or isocyanate groups.

Abstract: Disclosed herein are liquid polyisocyanate mixtures containing isocyanurate groups and having an NCO content of 15 to 30% by weight obtainable by partial trimerization of the isocyanate groups of polyisocyanate mixtures of the diphenyl methane series containing 80 to 100% by weight diisocyanatodiphenyl methane isomers and 0 to 20% by weight higher than difunctional polyisocyanates of the diphenyl methane series, 40 to 80% by weight of the diisocyanatodiphenyl methane isomers consisting of 4,4'-diisocyanatodiphenyl methane, 20 to 60% by weight of 2,4'-diisocyanatodiphenyl methane and 0 to 8% by weight of 2,2'-diisocyanatodiphenyl methane and the percentages shown adding up to 100.

Abstract: The present invention is directed to a process for the production of isocyanurate polyisocyanates containing aliphatically and/or cycloaliphatically bound isocyanate groups by trimerizing a portion of the isocyanate groups of organic diisocyanates containing aliphatically and/or cycloaliphatically bound isocyanate groups in the presence of a trimerization catalyst and terminating the trimerization reaction at the desired degree of trimerization by the addition of a catalyst poison, characterized in the quaternary ammonium fluorides are used as the catalyst.The present invention is also directed to the use of these isocyanurate polyisocyanates for the production of polyurethane lacquers.

Abstract: Improved microcapsules contain at least one wall which is the reaction product of at least one isocyanate-reactive group and an aromatic isocyanate which hasthe formula: ##STR1## in which n=8 to 20. The microcapsules are useful in carbonless copy paper.