Abstract: The invention relates to a process for producing rigid polyurethane foams by reacting a) polyisocyanates with b) compounds having at least two hydrogen atoms reactive toward isocyanate groups, in the presence of c) catalysts, and d) blowing agents, where, among the compounds having at least two hydrogen atoms reactive toward isocyanate groups, there is at least one graft polyol present capable of preparation via in-situ polymerization of ethylenically unsaturated monomers in polyether alcohols.

Abstract: The present invention relates to a process for the production of polyether alcohols by catalytic addition of alkylene oxides to H-functional initiators using amines as catalysts, wherein the addition of the amines to the reaction mixture is effected prior to or at the commencement of the chemical addition of the alkylene oxides and also at least once during the reaction, said additional addition of the catalyst being carried out at the point of the reaction at which there is an increased occurrence of side reactions and/or when the alkylene oxides undergo a change in the polyether chain.

Abstract: Polyetherols based on solid initiator substances and liquid, hydroxyl-containing coinitiators are prepared by a catalyzed addition reaction of alkylene oxides by a process in which the initiator combination contains diols carrying ethoxy structures, the ratio of the average number of hydroxyl groups per mole of initiator combination to the number of ethoxy structures in the polyetherol being from 1:0.2 to 1:1.8 and the ratio of the amounts by weight of the diols carrying ethoxy structures to the average molecular weight of the polyetherol being from 1:2 to 1:15. The polyetherols prepared by this process are used for the preparation of PUR, in particular, rigid PUR foams.

Abstract: Rigid polyurethane foams having a retarded reactivity are prepared by reacting organic and/or modified organic polyisocyanates (a) with a polyol mixture (b) and, if required, further compounds (c) having hydrogen atoms reactive toward isocyanates, in the presence of water (d), catalysts (e), flameproofing agents (f), blowing agents (g) and, if required, further assistants and additives (h), by a process in which the polyol mixture (b) consists of

Abstract: Polyetherols based on solid initiator substances and liquid, hydroxyl-containing coinitiators are prepared by a catalyzed addition reaction of alkylene oxides by a process in which the initiator combination contains ethoxy structures, the ratio of the average number of hydroxyl groups per mole of initiator combination to the number of ethoxy structures in the polyetherol being from 1:0.2 to 1:1.8 and the ratio of the amounts by weight of the ethoxy structures to the average molecular weight of the polyetherol being from 1:2 to 1:15.

Abstract: Polyurethanes having improved curing are prepared by reactinga) organic and/or modified organic diisocyanates and/or polyisocyanates withb) polyether polyols based on aromatic amines, able to be prepared by reacting specific amine combinations and, if desired, further coinitiators in a stage wise molecular addition of alkylene oxide, and also, if desired, further relatively high molecular weight compounds containing at least two reactive hydrogen atoms and, if desired,c) low molecular weight chain extenders and/or crosslinkers in the presence ofd) blowing agents,e) catalysts and, if desired,f) further auxiliaries and/or additives,wherein the specific amine combination used is a mixture of amines of the diphenylmethane series consisting of from 5 to 20% by weight of 4-ring amine, from 15 to 30% by weight of 3-ring amine, from 20 to 35% by weight of amines having more than 4 rings and from 25 to 50% by weight of 2-ring amine, wherein the proportions add up to 100% by weight, in combination with further aromatic

Abstract: A process for producing rigid polyurethane foams with reduced density by reactinga) organic and/or modified organic polyisocyanates withb) at least one higher-molecular-weight compound having at least two reactive hydrogen atoms and, if desired,c) low-molecular-weight chain extenders and/or crosslinkers in the presence ofd) blowing agents,e) catalysts and, if desired,f) other auxiliaries and/or additives,is described, which comprises using, as blowing agent (d), a mixture of cyclopentane with at least one compound which is homogeneously miscible with cyclopentane selected from the class consisting of the alkanes and/or alkenes having 3 or 4 carbon atoms in the molecule and with the carbon dioxide produced from water and isocyanate, and using, as higher-molecular-weight compound (b) having at least two reactive hydrogen atoms, polyethers which contain aromatics and nitrogen.The use of the rigid foams produced in this way as insulating material is also described.

Abstract: In a process for producing rigid foams based on isocyanate, the blowing agent used is a mixture of at least one low-boiling hydrocarbon having from 3 to 7 carbon atoms, low molecular weight monohydric alcohols containing primary or secondary hydroxyl groups and having from 1 to 4 carbon atoms, and, if desired, the carbon dioxide formed from water and isocyanate. The rigid foams can be used as insulation material.

Abstract: In a process for producing rigid foams based on isocyanate, the blowing agent used is a mixture of at least one low-boiling hydrocarbon having from 3 to 7 carbon atoms, low molecular weight monohydric alcohols containing primary or secondary hydroxyl groups and having from 1 to 4 carbon atoms, and, if desired, the carbon dioxide formed from water and isocyanate. The rigid foams can be used as insulation material.

Abstract: The invention relates to transparent, autoclavable, non-cytotoxic, essentially compact polyurethane embedding compositions which are prepared by reactinga) modified diphenylmethane diisocyanates withb) compounds with at least two reactive hydrogens, which contain or are composed ofb1) at least one polyether-polyol with an average functionality of from 3 to 8, a hydroxyl number of from 200 to 1000 and an alkali metal ion content of from 150 to 1200 ppm or, preferably, a mixture of (b1) and castor oil and/or at least one polyetherpolyol (b2) with a functionality of from 2 to 3, a hydroxyl number of from 90 to 200 and an alkali metal ion content of less than 10 ppm in the presence or absence ofc) catalysts and to a process for preparing the polyurethane embedding compositions and to the use thereof for articles used in medicine.