Abstract: The invention provides a process for removing nitrocresols from wastewater of mononitrotoluene preparation, which comprises acidifying the alkaline wastewater of mononitrotoluene preparation with acids to a pH of at most 3 and treating the nitrocresols with an extractant. The invention further provides the preparation of dinitrotoluene by use of the nitrocresol-containing extracts as a feedstock.

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: Prepolymers which contain isocyanate groups, have an NCO content of at least 30.0% by weight and can be prepared by reacting an isocyanate mixture consisting predominantly of diphenylmethane diisocyanates and polyphenylpolymethylene polyisocyanates and having a proportion of two-ring isomers of not more than 74% by weight with at least 4-functional polyols or a mixture of polyols having a mean functionality of at least 4, where the polyols or polyol mixtures have a hydroxyl number of from 200 to 1650 mg KOH/g and a number average molecular weight of less than 1100 g/mol.

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: A stable dispersion of melamine in polyol components comprising at least one relatively high molecular weight compound containing at least two reactive hydrogen atoms and, if desired, low molecular weight chain extenders and/or crosslinkers, blowing agents, catalysts, flame retardants and also further auxiliaries and/or additives is prepared by using the melamine in combination with at least one amine and at least one organic and/or modified organic isocyanate. Such a dispersion can be used for producing flame-resistant polyurethane foams.

Abstract: A stable dispersion of melamine in polyol components comprising at least one relatively high molecular weight compound containing at least two reactive hydrogen atoms and, if desired, low molecular weight chain extenders and/or crosslinkers, blowing agents, catalysts, flame retardants and also further auxiliaries and/or additives is prepared by using the melamine in combination with at least one amine and at least one organic and/or modified organic isocyanate.

Abstract: A stable dispersion of melamine in polyol components comprising at least one relatively high molecular weight compound containing at least two reactive hydrogen atoms and, if desired, low molecular weight chain extenders and/or crosslinkers, blowing agents, catalysts, flame retardants and also further auxiliaries and/or additives is prepared by using the melamine in combination with at least one amine and at least one organic and/or modified organic isocyanate. Such a dispersion can be used for producing flame-resistant polyurethane foams.

Abstract: The flameproofed, rigid, isocyanate-based foams, in particular rigid polyurethane and polyisocyanurate foams, are produced by reactinga) organic and/or modified organic polyisocyanates withb) at least one relatively high-molecular-weight compound containing at least two reactive hydrogen atoms, and, if desired,c) low-molecular-weight chain extenders and/or crosslinking agents, in the presence ofd) blowing agents,e) catalysts,f) flameproofing agents, and, if desired,g) further auxiliaries and/or additives,wherein the flameproofing agent is a combination of at least one liquid flameproofing agent which is reactive toward isocyanates and at least one solid flameproofing agent.

Abstract: In a process for producing open-celled rigid foams by reactinga) polyisocyanates withb) compounds containing hydrogen atoms which are reactive toward isocyanates, in the presence ofc) water,d) if desired, organic compounds acting as physical blowing agents,e) catalysts, auxiliaries and/or additives,the compounds containing reactive hydrogen atoms used are substances having the structure I: ##STR1## where m is 0-15n is 0-1o is 0-15p is 0-1q is 0-15r is 0-1s is 0-15t is 0-1u is 0-10v is 0-15x is 1-5y is 1-4 or mixtures of 1-3 where r+n.noteq.0z is 0-3z.sub.i is 0.1-3R.sub.1 is an aliphatic structure without OH groups based on the structure of polyhydric alcohols, preferably ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol and dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 1,3-butanediol, trimethylolpropane, trimethylolethane, glycerol, pentaerythritol, where these substances can also be used in the esterification as any mixture among one another and R.sub.

Abstract: The covering (13) of a printing roller (10) for transferring hot glue printing material from a printing block to the front panel of a display consists of cast silicone rubber without any silicone fluid. The use of silicone-fluid-free silicone rubber ensures that the printing materials will adhere well to the panel even in a sequence of printings, because the adhesion properties of the panel will not have been reduced by silicone fluid that would otherwise have been transferred from the roller to the panel. Although the roller covering is devoid of silicone fluid as stripping agent, the printing material nevertheless separates readily from the covering, because the latter is cast and therefore has a very smooth surface.

Abstract: For a flat display device, a control subassembly is needed which consists of two control plates (1;7) each formed by a layer of parallel conductors (2;8) which are isolated from each other. During the manufacture of the control subassembly, the first control plate is provided with a glass frit in the form of continuous strips (10) perpendicular to the conductors. The glass frit is set, and the application of the strips is repeated. The second control plate is then put on the first control plate in such a way that their conductors are mutually perpendicular. After that, the glass frit is crystallized.