Polyurethane-based polymer material having excellent resistance to heat distortion and elongation at tear

Abstract

The invention relates to a process for producing polyurethane materials by mixing (a) di- and / or polyisocyanates, (b) compounds with at an average of least 1.5 hydrogen atoms reactive toward isocyanates (excluding compounds with carbon-carbon double bonds), (c) compounds with carbon-carbon double bonds-either (c1) containing isocyanate groups or isocyanate-reactive groups, or (c2) with at least two double bonds. The mixture may be hardened above 120° C. The resulting material is stabilized such that when molded in a metal mold 20 × 30 × 0.4 cm at 80° C, demolded after 60 minutes, and cooled to room temperature, its heat-deflection temperature is at least 15° C lower than an otherwise identically produced polyurethane material which is heat-conditioned for a further 120 minutes at 150° C in an oven after the production process and then is cooled to room temperature.

Description

Polyurethane-based polymer material having excellent resistance to heat distortion and elongation at tear Description The present invention relates to processes for the production of a polyurethane material, where (a) di- and / or polyisocyanates, (b) compounds which have hydrogen atoms reactive toward isocyanate groups and which comprise no compounds having carbon-carbon double bonds, (c) compounds comprising at least one carbon-carbon double bond, (d) optionally catalyst that accelerates the urethane reaction, and (e) optionally other auxiliaries and additives are mixed to give a reaction mixture and the mixture is hardened at temperatures above 120°C, where the compounds b) having hydrogen atoms reactive toward isocyanate have, per molecule, an average of at least 1.5 hydrogen groups reactive toward isocyanate and the compounds (c) having carbon-carbon double bond comprise compounds (c1) of this type which have at least one carbon-carbon double bond and at least one group selected from groups reactive toward isocyanate or from isocyanate groups and / or (c2) which have at least two carbon-carbon double bonds, and where the reaction mixture has been stabilized to the extent that when components (a) to (c) and, if present, (d) and (e) are mixed at room temperature and the mixture is injected into a metal mold with the dimensions 20 cm x 30 cm x 0.4 cm controlled to a temperature of 80°C and is demolded after 60 minutes and cooled to room temperature the heat-deflection temperature (three-point bending with 0.45 MPa outer fiber stress in accordance with DIN EN ISO 75) of the resultant polyurethane material is at least 15°C lower than the heat-deflection temperature of the identically produced polyurethane material which is heat-conditioned for a further 120 minutes at 150°C in an oven after the production process and then is cooled to room temperature. The present invention further relates to a polyurethane material obtainable by this process, and also to the use of the polyurethane material, in particular of a polyurethane fiber-composite material as structural components. Polyurethane materials are versatile, but their high-temperature usage properties frequently require improvement. Polyurethane fiber-composite materials are known, and are usually obtained by pultrusion, fiber-winding processes or impregnation processes, for example vacuum infusion or RTM. The resultant fiber-composite materials have relatively low weight, with high hardness and stiffness, high corrosion resistance and good processability. Polyurethane fiber-composite materials are used, for example, as external bodywork components in vehicle construction, as boat hulls, as masts, for example as power masts or telegraph masts, or as rotor blades for wind turbines. A current trend is replacement of metals by plastics, for example as load-bearing components in the construction industry, or as bodywork components in vehicle construction. Polyurethane-based materials are frequently attractive for such purposes. These polyurethane-based materials have the disadvantage that their heat resistance is, in contrast to that of metals, frequently inadequate. When the intention is to replace load-bearing metal structures in regions where high thermal stress can arise, it is necessary that the polyurethane materials also have the ability to withstand high mechanical load, and that this ability extends to high temperatures. With this in mind, attempts are being made to increase the glass transition temperature of the polyurethane material, or of the polyurethane fiber-composite material. At the same time, these materials are intended to have high impact resistance at room temperature, for example in order to satisfy the requirements of the crash test. Replacement of metals in vehicle construction, for example as external bodywork components, also requires that these materials withstand high temperatures, in particular during cathodic electrocoating, which is conventional in automobile construction. Polyurethane materials can moreover also be used as adhesives, and for many applications, including for example adhesive applications in construction of bodywork for vehicles, must have high heat resistance. Prepregs are semifinished textile-fiber-matrix products which have been preimpregnated with reactive resins and are hardened with exposure to heat and pressure to produce components. The matrix here is in the partially crosslinked state known as the B-state, and has paste-like to solid consistency, and can be cured. Prepregs based on polyurethanes are known. These are based on blocked polyisocyanates, and are described by way of example in WO11147688, WO10108701 and WO10108723. However, this process leads to relatively high viscosity and therefore to disadvantages during impregnation. The use of blocked catalysts moreover requires a very high isocyanate index as described in WO 2013139704. This high excess of isocyanate leads to increased sensitivity to humidity. Known prepregs are therefore preferably stored in a vacuum bag with exclusion of air. It was therefore an object to provide a polyurethane material with increased resistance to temperature change. Another object of the present invention was to provide a simple process for improving the mechanical properties of polyurethane at high temperatures, and thus to provide access to polyurethanes which can be used as replacement for metal structures, for example in the cathodic electrocoating process, or can be used as load-bearing structures. Finally, it was an object of the present invention to provide polyurethane materials which have high mechanical stability at high temperatures and at the same time have high impact resistance at room temperature. Another object, in particular for the use of these polyurethane materials in the context of fiber-composite materials, was to ensure minimized viscosity of the reaction mixture at room temperature, thus permitting rapid impregnation of the fibers. Surprisingly, this object is achieved via a process in which (a) di- and / or polyisocyanates, (b) compounds which have hydrogen atoms reactive toward isocyanate groups and which comprise no compounds having carbon-carbon double bonds, (c) compounds comprising at least one carbon-carbon double bond, (d) optionally catalyst that accelerates the urethane reaction, and (e) optionally other auxiliaries and additives are mixed to give a reaction mixture and the mixture is hardened at temperatures above 120°C, where the compounds b) having hydrogen atoms reactive toward isocyanate have, per molecule, an average of at least 1.5 hydrogen groups reactive toward isocyanate and the compounds (c) having carbon-carbon double bond comprise compounds (c1) of this type which have at least one carbon-carbon double bond and at least one group selected from groups reactive toward isocyanate or from isocyanate groups and / or (c2) which have at least two carbon-carbon double bonds, and where the reaction mixture has been stabilized to the extent that when components (a) to (c) and, if present, (d) and (e) are mixed at room temperature and the mixture is injected into a metal mold with the dimensions 20 cm x 30 cm x 0.4 cm controlled to a temperature of 80°C and is demolded after 60 minutes and cooled to room temperature the heat-deflection temperature (three-point bending with 0.45 MPa outer fiber stress in accordance with DIN EN ISO 75) of the resultant polyurethane material is at least 15°C lower than the heat-deflection temperature of the identically produced polyurethane material which is heat-conditioned for a further 120 minutes at 150°C in an oven after the production process and then is cooled to room temperature. The object of the invention is moreover achieved via a polyurethane material obtainable by this process. For the purposes of the invention, the term "polyurethane" encompasses all known polyisocyanate polyaddition products. These encompass addition products derived from isocyanate and alcohol, and also encompass modified polyurethanes, which can comprise isocyanurate structures, allophanate structures, urea structures, carbodiimide structures, uretonimine structures, biuret structures, and other isocyanate addition products. These polyurethanes of the invention in particular comprise solid polyisocyanate polyaddition products, for example thermosets, and foams based on polyisocyanate polyaddition products, in particular rigid polyurethane foams, and also polyurethane coatings. In another preferred embodiment, the polyurethane is a solid polyurethane with density preferably above 850 g / L, preferably 900 to 1400 g / L and particularly preferably 1000 to 1300 g / L. A solid polyurethane is obtained here, without addition of any blowing agent. For the purposes of the present invention, small quantities of blowing agent, for example water present in the polyols as a result of the production process, are not interpreted here as constituting addition of blowing agent. The reaction mixture for the production of the compact polyurethane preferably comprises less than 0.2% by weight, with particular preference less than 0.1% by weight and in particular less than 0.05% by weight, of water. The solid polyurethane preferably comprises fillers, in particular fibrous fillers. Suitable fillers are described under (e). Materials that can be used as di- or polyisocyanates (a) are any of the aliphatic, cycloaliphatic or aromatic isocyanates known for the production of polyurethanes, and also any desired mixtures thereof. Examples are diphenylmethane 2,2'-, 2,4'- and 4,4'-diisocyanate, the mixtures of monomeric diphenylmethane diisocyanates with diphenylmethane diisocyanate homologs having a larger number of rings (polymer MDI), isophorone diisocyanate (IPDI) and its oligomers, tolylene 2,4- or 2,6-diisocyanate (TDI) and mixtures of these, tetramethylene diisocyanate and its oligomers, hexamethylene diisocyanate (HDI) and its oligomers, naphthylene diisocyanate (NDI) and mixtures thereof. Materials used as di- or polyisocyanates (a) are preferably isocyanates based on diphenylmethane diisocyanate, for example 2,4'-MDI, 4,4'-MDI or a mixture of these components, or possibly also with MDI homologs having a larger number of rings. The functionality of the di- and polyisocyanates (a) is preferably 2.0 to 2.9, with particular preference 2.0 to 2.8. The viscosity of the di- or polyisocyanates (a) at 25°C in accordance with DIN 53019-1 to 3 here is preferably between 5 and 600 mPas and with particular preference between 10 and 300 mPas. The di- and / or polyisocyanates (a) with particular preference comprise at least 50 mol%, with greater preference 60 to 100 mol% and in particular 70 to 90 mol%, of isocyanates with functionality of 2. Di- and polyisocyanates (a) used can also take the form of polyisocyanate prepolymers. These polyisocyanate prepolymers are obtainable from reaction of polyisocyanates described above (constituent (a-1)) in excess, for example at temperatures of 30°C to 100°C, with preference at about 80°C, with compounds having at least two groups reactive toward isocyanates (constituent (a-2)), to give the prepolymer. The NCO content of polyisocyanate prepolymers of the invention is preferably 20 to 33% by weight of NCO, with particular preference 25 to 30% by weight of NCO. Compounds (a-2) having at least two groups reactive toward isocyanates are known to the person skilled in the art and are described by way of example in "Kunststoffhandbuch, 7, Polyurethane" [Plastics Handbook, volume 7, Polyurethanes], Carl Hanser Verlag, 3rd edition 1993, chapter 3.1. Compounds used having at least two groups reactive toward isocyanates can, for example, therefore be polyetherols or polyesterols, for example those described below under (b). It is preferable that compounds (a-2) used as compounds having at least two groups reactive toward isocyanates are polyetherols or polyesterols comprising secondary OH groups, an example being polypropylene oxide. The functionality of the polyetherols or polyesterols here is preferably 2 to 4, with particular preference 2 to 3, and they preferably have a proportion of at least 50% of secondary OH groups, preferably at least 75% and in particular at least 85%. Compounds (b) used having, per molecule, an average of at least 1.5 hydrogen atoms reactive toward isocyanate groups can be any of the compounds that are known in polyurethane chemistry and have hydrogen atoms reactive toward isocyanates; compounds having carbon- carbon double bonds and molar mass below 800 g / mol do not qualify as compounds (b) here, but instead are covered by the definition of the compounds (c). The average functionality of compounds (b) is at least 1.5, preferably 1.7 to 8, with particular preference 1.9 to 6 and in particular 2 to 4. These comprise chain extenders and crosslinking agents with OH functionality of 2 to 6 and with molar mass below 300 g / mol, preferably functionality of 2 to 4 and with particular preference 2 to 3, and also higher-molecular-weight compounds having hydrogen atoms reactive toward isocyanate and molar mass of 300 g / mol and above. The expression "chain extenders" here means molecules having two hydrogen atoms reactive toward isocyanate; the expression "crosslinking agents" is used for molecules having more than two hydrogen atoms reactive toward isocyanate. These can be used individually, or with preference in the form of mixtures. It is preferable to use diamines, diols and / or triols having molar masses below 300 g / mol, with particular preference 62 g / mol to below 300 g / mol and in particular 62 g / mol to 250 g / mol. Compounds that can be used are by way of example aliphatic, cycloaliphatic and / or araliphatic or aromatic diamines and diols having 2 to 14, preferably 2 to 10, carbon atoms, for example diethyltoluenediamines (DEDTA), m- phenylenediamines, ethylene glycol, 1,2-propanediol, 2-methyl-1,3-propanediol, 1,3- propanediol, 1,4-butanediol, 1,6-hexanediol, 1,10-decanediol and bis(2- hydroxyethyl)hydroquinone (HQEE), 1,2-, 1,3-, 1,4-dihydroxycyclohexane, bisphenol A bis(hydroxyethyl ether), diethylene glycol, dipropylene glycol, tripropylene glycol, triols, for example 1,2,4-, 1,3,5-trihydroxycyclohexane, glycerol and trimethylolpropane, 7 diethanolamines, triethanolamines, and low-molecular-weight hydroxylated polyalkylene oxides based on ethylene oxide and / or on propylene 1,2-oxide and on the abovementioned diols and / or triols, as starter molecules. Compounds used as crosslinking agents are with particular preference low-molecular-weight hydroxylated polyalkylene oxides based on ethylene oxide and / or on propylene 1,2-oxide, with particular preference on 1,2 propylene, and on trifunctional starters, in particular glycerol and trimethylolpropane. Chain extenders to which particular preference is given are ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2- methyl-1,3-propanediol, 1,4-butanediol, diethylene glycol, bis(2-hydroxyethyl)hydroquinone and dipropylene glycol. If chain extenders and / or crosslinking agents are used, the proportion of chain extenders and / or crosslinking agents (e) is usually 1 to 50% by weight, preferably 2 to 20% by weight, based on the total weight of components (a) to (e). However, it is also possible here to omit the chain extenders or crosslinking agents. Addition of chain extenders, crosslinking agents, or optionally also mixtures thereof, can however prove to be advantageous for modifying mechanical properties, e.g. hardness. The number-average molar mass of higher-molecular-weight compounds having hydrogen atoms reactive toward isocyanate is preferably 400 to 15 000 g / mol. It is therefore possible by way of example to use compounds selected from the group of the polyether polyols, polyester polyols and mixtures thereof. Polyetherols are by way of example produced from epoxides, for example propylene oxide and / or ethylene oxide, or from tetrahydrofuran with starter compounds having active hydrogen atoms, examples being aliphatic alcohols, phenols, amines, carboxylic acids, water and compounds based on natural substances, e.g. sucrose, sorbitol or mannitol, with use of a catalyst. Mention may be made here of basic catalysts or double-metal cyanide catalysts, as described for example in PCT / EP2005 / 010124, EP 90444 or WO 05 / 090440. Polyesterols are by way of example produced from aliphatic or aromatic dicarboxylic acids and polyhydric alcohols, polythioether polyols, polyesteramides, hydroxylated polyacetals and / or hydroxylated aliphatic polycarbonates, preferably in the presence of an esterification catalyst. Other possible polyols are set out by way of example in "Kunststoffhandbuch, Band 7, Polyurethane" [Plastics Handbook, volume 7, Polyurethanes], Carl Hanser Verlag, 3rd edition 1993, chapter 3.1. It is preferable that the higher-molecular-weight compounds having hydrogen atoms reactive toward isocyanates comprise compounds having hydrophobic groups. With particular preference, these are hydroxy-functionalized compounds having hydrophobic groups. These hydrophobic groups comprise hydrocarbon groups having preferably more than 6, with particular preference more than 8 and less than 100, and in particular more than 10 and less than 50, carbon atoms. It is preferable to use, as hydroxy-functionalized hydrophobic compound, a hydroxy- functionalized oleochemical compound, an oleochemical polyol. There are many known hydroxy-functional oleochemical compounds that can be used. Examples are castor oil, hydroxylated oils, for example grapeseed oil, black cumin oil, pumpkin seed oil, borage seed oil, soybean oil, wheatgerm oil, rapeseed oil, sunflower oil, peanut oil, apricot kernel oil, pistachio kernel oil, almond oil, olive oil, macadamia nut oil, avocado oil, sea buckthorn oil, sesame oil, hazelnut oil, evening primrose oil, wild rose oil, hemp oil, safflower oil, walnut oil, hydroxylated fatty acid esters based on myristoleic acid, palmitoleic acid, oleic acid, vaccenic acid, petroselinic acid, gadoleic acid, erucic acid, nervonic acid, linoleic acid, linolenic acid, stearidonic acid, arachidonic acid, timnodonic acid, clupanodonic acid, cervonic acid. Materials used with preference here are castor oil and products of reaction thereof with alkylene oxides or with ketone-formaldehyde resins. The latter compounds are marketed for example under the name Desmophen® 1150 by Bayer AG. Another group of oleochemical polyols used with preference can be obtained via ring- opening of epoxidized fatty acid esters with simultaneous reaction with alcohols and optionally with subsequent further transesterification reactions. Incorporation of hydroxy groups into oils and fats is primarily achieved via epoxidation of the olefinic double bond comprised in these materials and subsequent reaction of the resultant epoxy groups with a mono- or polyhydric alcohol. The epoxide ring here becomes a hydroxy group or, in the case of polyhydric alcohols, a structure with a larger number of OH groups. Because oils and fats are mostly glycerol esters, the abovementioned reactions are also accompanied by parallel transesterification reactions. The resultant compounds preferably have a molar mass in the range between 500 and 1500 g / mol. Products of this type are supplied by way of example by BASF (as Sovermol®) or by Altropol Kunststoff GmbH as Neukapol®. Oleochemical polyols whose molar mass is below 1000 g / mol comprising carbon-carbon double bonds are classified here as compounds (c). The compounds (c) comprise at least one carbon-carbon double bond. The compounds (c) moreover comprise compounds (c1) which have at least one carbon-carbon double bond and at least one group selected from groups reactive toward isocyanate or from isocyanate groups and / or (c2) which have at least two carbon-carbon double bonds. If compounds (c1) which have at least one group reactive toward isocyanate and at least one carbon-carbon double bond are comprised, these are concomitantly taken into account in the determination of the average functionality of the compounds having hydrogen atoms reactive toward isocyanate. It is preferable here that the proportion of the entirety of the compounds (c1) and (c2), based on the total quantity of compounds (c), is 5 to 100 mol%, preferably 8 to 90 mol% and with particular preference 10 to 80 mol%. The compounds (c1) and (c2) here can be used in any desired ratio to one another. In an embodiment to which particular preference is given, no compound (c1) is used. In an embodiment to which preference is given, 60 to 100%, preferably 70 to 100% and with particular preference 90 to 100%, of the carbon-carbon double bonds in the compounds (c) are terminal carbon-carbon double bonds. Examples of typical compounds (c) are butadiene, isoprene, 1,3-pentadiene, 1,5-hexadiene, 1,7-octadiene, styrene, alpha-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4- methylstyrene, 2,4-dimethylstyrene, ethylstyrene, isopropylstyrene, butylstyrene, phenylstyrene, cyclohexylstyrene, benzylstyrene and similar derivatives; substituted styrenes such as cyanostyrene, nitrostyrene, N,N-dimethylaminostyrene, acetoxystyrene, methyl 4- vinylbenzoate, phenoxystyrene, p-vinylphenyoxide and similar derivatives and mixtures thereof; acrylates and substituted acrylates, for example acrylonitrile, acrylic acid, methacrylic acid, methacrylic acrylate, 2-hydroxyethyl acrylate, methyl methacrylate, cyclohexyl methacrylate, benyzyl methacrylate, isopropyl methacrylate, octyl methacrylate, methacrylonitrile, ethyl alpha-ethoxyacrylate, methyl alpha-acetaminoacrylates, butyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, phenyl methacrylate, acrylamide, N,N- dimethylacrylamide, N-butylacrylamide, methacryloylformamide, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, and similar derivatives and mixtures thereof; vinyl esters, vinyl ethers, vinyl ketones, etc., for example vinyl acetate, vinyl butyrate, vinyl formate, vinyl acrylates, vinyl methacrylate, vinyl methoxyacetate, vinyl benzoate, vinyltoluene, vinyl methyl ether, vinyl propyl ether, vinyl butyl ether, vinyl 2-ethylhexyl ether, vinyl phenyl ether, vinyl 2- methoxyethyl ether, methoxybutadiene, vinyl methyl ketone, vinyl ethyl ketone, N-methyl-N- vinylacetamide, dinvinyl sulfoxide, divinyl sulfone, sodium vinylsulfonate, methyl vinylsulfonate, divinyl ether derivatives, e.g. diethylene glycol divinyl ether or triethylene glycol divinyl ether, trimethylolpropane triallyl ether, trimethylolpropane diallyl ether, glyoxalbis(diallyl acetal) and similar derivatives; dimethyl fumarate, dimethyl maleate, maleic acid, fumaric acid, dimethylaminoethyl methacrylate, glycidyl acrylate, allyl alcohol, triallyl cyanurate, trivinyl cyanurate, cyanuric acid triallyl ether, 2,4,6-triallyloxy-1,3,5-triazine, 2,4,6-trivinyloxy-1,3,5- triazine, 1,3,5-triacryloylhexahydro-1,3,5-triazine, tris[2-(acryloyloxy)ethyl] isocyanurate, cyanuric acid trivinyl ether, 1,2,4-trivinylcyclohexane, polybutadiene, modified polybutadienes, for example hydroxy-terminated polybutadienes and mixtures thereof, alkylene malonates such as methylene malonate, cyanoacrylic acid vinyl ether; bisphenol A diacrylate, bisphenol A dimethacrylate, bisphenol A epoxy diacrylates, bisphenol A epoxy dimethacrylates; pentaerythritol monoacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, alkoxylated pentaerythritol monoacrylate, alkoxylated pentaerythritol diacrylate, alkoxylated pentaerythritol triacrylate, alkoxylated pentaerythritol tetraacrylate, glycerol monoacrylate, glycerol diacrylate, glycerol triacrylate, alkoxylated glycerol monoacrylate, alkoxylated glycerol diacrylate, alkoxylated glycerol triacrylate, trimethylolpropane monoacrylate, trimethylolpropane diacrylate, trimethylolpropane triacrylate, alkoxylated trimethylolpropane monoacrylate, alkoxylated trimethylolpropane diacrylate, alkoxylated trimethylolpropane triacrylate, bistrimethylolpropane tetraacrylate, bistrimethylolpropane triacrylate, bistrimethylolpropane diacrylate, bistrimethylolpropane monoacrylate, butanediol diacrylate, tripropylene glycol monoacrylate, tripropylene glycol diacrylate, dipropylene glycol diacrylate, dipropylene glycol monoacrylate, butanediol diacrylate, butanediol monoacrylate, triethylene glycol diacrylate, triethylene glycol monoacrylate, diethylene glycol diacrylate, diethylene glycol monoacrylate, hexanediol diacrylate, hexanediol monoacrylate, pentaerythritol monomethacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, alkoxylated pentaerythritol monomethacrylate, alkoxylated pentaerythritol dimethacrylate, alkoxylated pentaerythritol trimethacrylate, alkoxylated pentaerythritol tetramethacrylate, glycerol monomethacrylate, glycerol dimethacrylate, glycerol trimethacrylate, alkoxylated glycerol monomethacrylate, alkoxylated glycerol dimethacrylate, alkoxylated glycerol trimethacrylate, trimethylolpropane monomethacrylate, trimethylolpropane dimethacrylate, trimethylolpropane trimethacrylate, alkoxylated trimethylolpropane monomethacrylate, alkoxylated trimethylolpropane dimethacrylate, alkoxylated trimethylolpropane trimethacrylate, bistrimethylolpropane tetramethacrylate, bistrimethylolpropane trimethacrylate, bistrimethylolpropane dimethacrylate, bistrimethylolpropane monomethacrylate, tripropylene glycol dimethacrylate, dipropylene glycol dimethacrylate, triethylene glycol dimethacrylate, diethylene glycol dimethacrylate, butanediol dimethacrylate, butanediol monomethacrylate, hexanediol dimethacrylate, hexanediol monomethacrylate, and moreover oligomeric reaction products of trimethylolpropane with, for example, acetoacetate or with bis(acetoacetates) as, for example, described in WO0100684, WO03 / 031502, WO04 / 029118, WO05012394, WO09014689, Ebecry LEO (amine-modified polyether acrylates) from Allnex. 12 It is preferable that the double-bond functionality of the compound (c) is greater than 1. Preferred ethylenically unsaturated monomers are methyl acrylate, trimethylolpropane triacrylate, and hydroxy-terminated polybutadiene, obtainable with tradename Krasol, and mixtures thereof. It is possible by way of example to use polyfunctional olefins and monofunctional olefins together and thus firstly to optimize the crosslinking density of the product and secondly to optimize the viscosity of the starting materials; the monofunctional olefin here can be either isocyanate-reactive or not. The proportion of the compounds (c), based in each case on the total weight of components (a) to (e), is preferably 10 to 70% by weight, with particular preference 25 to 60% by weight and in particular 30 to 50% by weight. In an embodiment to which preference is given here, the double-bond density, based on the starting materials, and also the total weight of components (a) to (e), is preferably above 0.1% by weight, with preference 1.0 to 30% by weight and in particular 4.0 to 16% by weight. For the purposes of the present invention, the expression "double-bond density" here means the proportion by mass of the double bonds in relation to the total mass of components (a) to (e). The mass assumed here for a terminal double bond is 27 g / mol (-CH=CH<com:Sub>2< / com:Sub>; 2 times carbon plus 3 times hydrogen). In another embodiment it is also possible to add, to the isocyanate component, such components c) which comprise no hydrogen atoms reactive toward isocyanates. In another embodiment to which preference is given, the ratio of isocyanate groups of the di- and polyisocyanates (a) to the number of carbon-carbon double bonds of the compound (c) is 0.1 to 1 up to 4 to 1, with more preference 0.4 to 1 up to 3 to 1 and in particular 0.5 to 1 up to 2 to 1. Catalysts (d) used can be conventional polyurethane catalysts. These greatly accelerate the reaction of the compounds (b) having hydrogen atoms reactive toward isocyanates with the di- and polyisocyanates (a). The following may be mentioned as examples of conventional catalysts that can be used for the production of the polyurethanes: amidines, for example 2,3- dimethyl-3,4,5,6-tetrahydropyrimidine, tertiary amines, for example triethylamine, tributylamine, dimethylbenzylamine, dimethylcyclohexylamine, N-methyl-, N-ethyl- and N- cyclohexylmorpholine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'- tetramethylbutanediamine, N,N,N',N'-tetramethylhexanediamine, pentamethyldiethylenetriamine, tetramethyldiaminoethyl ether, bis(dimethylaminopropyl)urea, dimethylpiperazine, 1,2-dimethylimidazole, 1-azabicyclo[3.3.0]octane, and preferably 1,4- diazabicyclo[2.2.2]octane, and alkanolamine compounds, for example triethanolamine, triisopropanolamine, N-methyl- and N-ethyldiethanolamine and dimethylethanolamine. It is also possible to use organometallic compounds, preferably organic tin compounds, for example tin(II) salts of organic carboxylic acids, e.g. tin(II) acetate, tin(II) octanoate, tin(II) ethylhexanoate and tin(II) laurate, and the dialkyltin(IV) salts of organic carboxylic acids, e.g. dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate and dioctyltin diacetate, and also bismuth carboxylates, for example bismuth(III) neodecanoate, bismuth 2-ethylhexanoate and bismuth octanoate, or a mixture thereof. The organometallic compounds can be used alone or preferably in combination with strongly basic amines. If component (b) is an ester, it is preferable to use exclusively amine catalysts. The concentration used of catalysts (d), in the form of catalyst or catalyst combination, can by way of example be 0.001 to 5% by weight, in particular 0.05 to 2% by weight, based on the weight of component (b). Auxiliaries and / or additives (e) can moreover also be used. Any of the auxiliaries and additives known for the production of polyurethanes can be used here. Mention may be made by way of example of surface-active substances, blowing agents, foam stabilizers, cell regulators, release agents, fillers, dyes, pigments, flame retardants, hydrolysis stabilizers, and fungistatic and bacteriostatic substances. These substances are known and are described by way of example in "Kunststoffhandbuch, Band 7, Polyurethane" [Plastics Handbook, volume 7, Polyurethanes], Carl Hanser Verlag, 3rd edition 1993, chapters 3.4.4 and 3.4.6 to 3.4.11. In an embodiment to which further preference is given, the auxiliaries and additives (e) can comprise basic catalysts which are not conventional polyurethane-forming catalysts. These comprise by way of example the catalysts that catalyze formation of polyisocyanurate. Polyisocyanurate catalysts comprise alkali metal carboxylates. With preference, these comprise formates and acetates, in particular acetates, for example sodium acetate and potassium acetate. In contrast, compounds comprising epoxy groups are not required for the production of the polyurethane materials of the invention. It is preferable that the polyurethane material of the invention in essence comprises no compounds comprising epoxy groups. The proportion of compounds comprising epoxy groups, based on the total weight of components (a) to (e) is therefore preferably below 1% by weight, with particular preference below 0.1% by weight. The quantities reacted of the di- and / or polyisocyanates (a), the compounds (b) having hydrogen atoms reactive toward isocyanate groups and, if other compounds having hydrogen atoms reactive toward isocyanate, for example blowing agents, are generally such that, during the production of the polyurethane material of the invention, the equivalence ratio of NCO groups of the polyisocyanates (a) to the entirety of the hydrogen atoms that are reactive toward isocyanate groups that are present in the other components is 0.7 to 1.4, preferably 0.8 to 1.2, with particular preference 0.9 to 1.1 and in particular 1.0. A ratio of 1:1 here corresponds to an isocyanate index of 100. Hardening then takes place at temperatures above 120°C, with preference at 140 to 225°C, with particular preference at 150 to 210°C and in particular at 160 to 200°C. Production of polyurethanes of the invention in the form of an elastomer, a rigid foam or a thermoset involves only slight quantitative and qualitative differences in the respective specific starting substances (a) to (e) for the production of polyurethanes of the invention. By way of example, no blowing agents are used for the production of solid polyurethanes. It is moreover possible by way of example to vary the elasticity and hardness of the polyurethane of the invention by way of the functionality and the chain length of the higher-molecular-weight compound having at least two reactive hydrogen atoms. Such modifications are known to the person skilled in the art. The starting materials for the production of a solid polyurethane are described by way of example in EP 0989146 or EP 1460094, and the starting materials for the production of a rigid foam are described by way of example in PCT / EP2005 / 010955. In each case, the compound (c) is then added to the starting materials described in said documents. It is essential to the invention here that the reaction mixture has been stabilized. For the purposes of the invention, the reaction mixture has been stabilized if when the components are mixed at room temperature and the mixture is injected into a metal mold with the dimensions 20 cm x 30 cm x 0.4 cm controlled to a temperature of 80°C and is demolded after 60 minutes and cooled to room temperature the heat-deflection temperature of the resultant polyurethane material in three-point bending with 0.45 MPa outer fiber stress in accordance with DIN EN ISO 75 is at least 15°C, with preference at least 25°C, with more preference at least 40°C and in particular at least 60°C lower than the heat-deflection temperature of the identically produced polyurethane material which is heat-conditioned for a further 120 minutes at 150°C in an oven after the production process and then is cooled to room temperature. This stabilization can be achieved via addition of free-radical inhibitor. Free-radical inhibitors used can be substances which lead to termination of the free-radical polymerization of the carbon-carbon double bonds. Free-radical inhibitors, also termed free-radical scavengers, encompass bis(trifluoromethyl)nitroxide, free aminoxyl radicals, 2,2-diphenyl-1-picrylhydrazyl and 2,2,6,6-tetramethylpiperidin-1-yloxy. Preferred free-radical inhibitors are phenothiazine, nitrobenzene, hydroquinone monomethyl ether, p-benzoquinone and diphenylpicrylhydrazyl. In a preferred embodiment, the reaction mixture comprises, based on the total weight of components (a) to (e), 0.0001 to 2.0% by weight of free-radical inhibitor, preferably 0.0005 to 1.0% by weight, and in particular 0.001 to 0.5% by weight. Stabilization does not always require the addition of free-radical inhibitor. It is therefore also possible that the reactivity, in particular the reactivity of the compounds having at least one carbon-carbon double bond (c) is sufficiently low not to require any addition of the free-radical inhibitor in order to achieve stabilization at 80°C. With further preference, the reaction mixture of the invention comprises no compounds that initiate a free-radical reaction. These encompass traditional free-radical initiators, for example peroxides, e.g. dibenzoyl peroxide, disulfides, onium compounds and AIBN and photoinitiators, for example <com:Math><semantics>α<annotation encoding="application / x-tex">\alpha< / annotation>< / semantics>< / com:Math>-hydroxy-, <com:Math><semantics>α<annotation encoding="application / x-tex">\alpha< / annotation>< / semantics>< / com:Math>-alkoxy- or <com:Math><semantics>α<annotation encoding="application / x-tex">\alpha< / annotation>< / semantics>< / com:Math>-aminoarylketones and also acylphosphine oxides, and also photolabile aliphatic azo compounds, and mixtures of the compounds mentioned. The above also includes the absence of components which could be formed after the reaction components have been placed into storage and could initiate free- radical reactions. The reaction mixture of the invention can therefore comprise compounds which bring about decomposition of peroxides, examples being organic sulfides, phosphites and phosphonites. It is preferable that the two-component method is used to produce the reaction mixture. For this, the compounds (b) to (d) and optionally (e) are combined to give a polyol component. The isocyanate component comprises isocyanates (a) and optionally constituents for component (e). It is preferable that the composition of the polyol component here is adjusted to a viscosity that is preferably below 1000 mPas at 25°C. The viscosity measurement here is based on DIN 53019-1 to 3. The viscosity adjustment here can in particular be achieved by way of the selection of the compound of component (c), and also the quantity used thereof. The viscosity of the polyol component can in particular be reduced by use of acrylates. In an embodiment to which preference is given, the reaction is conducted as a one-pot reaction after mixing all components a) to e), by way of two-stage hardening. After mixing of components (a) to (e), the reaction mixture here is kept for a period of at least 10 minutes, with preference 10 to 30 minutes at temperatures below 120°C, with preference in the temperature range 30 to 110°C, with greater preference 50 to 80°C. In a second step, the reaction to give the polyurethane material of the invention is continued at a temperature above 120°C, preferably at a temperature above 150°C and in particular at a temperature in the range of 160 to 225°C. The temperature in the second step here is usually maintained for at least 2 minutes, preferably 3 to 120 minutes and with particular preference 10 to 60 minutes. It is also possible here that, after the first step, the reaction mixture is cooled, for example to temperatures of -20 to 30°C. At this temperature, the reaction mixture is amenable to storage after conclusion of the first step, and can be stored for several weeks. The invention provides not only the process of the invention but also a polyurethane obtainable by a process of the invention. In an embodiment of the present invention to which preference is given, the polyurethane material of the invention is a polyurethane fiber-composite material. It is produced by using the reaction mixture to wet fibers and then hardening to give the polyurethane fiber- composite material. Preferred fibers used are glass fibers, carbon fibers, polyester fibers, natural fibers, for example cellulose fibers, aramid fibers, nylon fibers, basalt fibers, boron fibers, Zylon fibers (poly(p-phenylene-2,6-benzobisoxazole)), silicon carbide fibers, asbestos fibers, metal fibers and combinations thereof. These can by way of example take the form of short or long glass fibers, continuous fibers, laid scrims, knitted fabrics, random-fiber matts, and plies with identical or different fiber orientation. Techniques for the wetting of the fibers are subject to no restriction and are well known. These encompass by way of example the fiber-winding process, the pultrusion process, the manual lamination process and the infusion process, for example the vacuum infusion process. The polyurethane materials of the invention, in particular the polyurethane fiber-composite materials of the invention, exhibit improved heat resistance, increased glass transition temperature, very good resistance to water and hydrophobic liquids and very good properties under long-term stress. With particular preference, the heat-deflection temperature of the polyurethane materials of the invention in three-point bending with 0.45 MPa outer fiber stress in accordance with DIN EN ISO 75 is above 120°C, with greater preference above 130°C and in particular above 140°C, together with (Charpy) DIN EN ISO 179-1 / 1fU impact resistance above <com:Math><semantics>25 kJ / m2<annotation encoding="application / x-tex">25 \text{ kJ / m}^2< / annotation>< / semantics>< / com:Math>. Polyurethane fiber-composite materials of the invention can by way of example be used as adhesives, particularly for regions exposed to high thermal stress, structural components, for example external bodywork components in vehicle construction, for example wheel surrounds, boat hulls, hot-water containers, for example for household use, or as components of electric motors, masts, for example power masts or telegraph masts, insulators and other components in the field of high-voltage technology, rotor blades for wind turbines, or as pipes, for example fiber-reinforced pipelines for the oil and gas industry, or as equipment and ancillaries for drilling, production and transport of oil and gas. The polyurethane materials of the invention are moreover suitable for use in cathodic electrocoating, which is in particular used in the automobile industry. In particular in the production of pipes, by using 25 to 60 parts by weight, with particular preference 30 to 50 parts by weight, of component (c), based in each case on the total weight of components (a) to (e), in combination with use of polyol comprising hydrophobic groups as compound (b) it is possible, even in tropical climates with temperatures in the range of 25 to 40°C and with relative humidity of more than 50% up to more than 90%, to obtain polyurethane materials which are in essence free from gas bubbles, have high solvent resistance which also extends to hydrophobic liquids, and have a high glass transition temperature and therefore can be used when the temperature of the fluid to be conducted is high. The reaction mixture of the invention can moreover be used in vacuum infusion. For this, it is preferable to use 2 to 15% by weight, with preference 3 to 10% by weight, of compounds of component (c), based on the total weight of components (a) to (e), together with higher- molecular-weight compounds (b) which have an average functionality of preferably 1.5 to 2.2, with greater preference 1.8 to 2.1 and in particular 1.9 to 2.05. Component (b) can optionally moreover comprise chain extenders, for example 2 to 30% by weight, based on the total weight of components (a) to (e). Such reaction mixtures in particular feature low shrinkage on hardening, good flowability and long open time. The reaction mixture of the invention can moreover be used for the production of storage- stable polyurethane prepregs via impregnation of fibrous woven fabrics or laid scrims at temperatures preferably below 100°C, with particular preference below 80°C and in particular below 50°C with subsequent hardening at temperatures above 120°C, preferably 140°C to 225°C, with greater preference 150°C to 210°C and in particular 160°C to 200°C. These prepregs of the invention are stable for long periods in storage at room temperature, and can be hardened rapidly at temperatures above 120°C. In the B-state of the polyurethane prepreg of the invention (i.e. in the uncured state), the polyurethane reaction has already progressed to a large extent, and preferably in essence has concluded. The isocyanate content (NCO content) of the polyurethane prepreg is preferably 0 to 1% by weight of NCO, with particular preference 0 to 0.1% by weight of NCO. An advantageous property of the prepreg resins is passage through a B-state in which the resin has undergone only prepolymerization or partial polymerization, exhibits very little tack, and can be molded via change of temperature and, possibly, pressure before finally, at elevated temperature, the resin undergoes full hardening and a high degree of crosslinking. If polyols used have a high equivalent weight, for example above 1000 g / mol, resultant intermediate stages are slightly tackier and can be combined with, and bonded to, one another, and are dimensionally stable in the finally hardened state. If a tack-free intermediate stage is desired, this can be achieved by reducing the proportions of the polyols with high equivalent weight. The reaction mixtures of the invention here exhibit low viscosity together with good impregnation properties. Because the reaction mixture of the invention has low viscosity at temperatures below 80°C, for example at 10 to 30°C, it is possible to skim reaction mixture from the impregnated fiber material and thus obtain a high proportion of fiber by volume. Preference is therefore given to an impregnation technique in which excess resin can be efficiently removed from the fibers and reused. The invention will be illustrated below with reference to examples. [Image disponible dans le document PDF, Image available in the PDF document] Table 1: Production of resins resistant to temperature change 5 Starting materials (data in percent by weight in all tables). Usual batch size: 300 g of polyol component are mixed at room temperature; the isocyanate is then added and the mixture is mixed for 60 s in a high-speed mixer (FA Hauschild); the reaction mixture is then cast into a metal mold measuring 20 x 30 x 0.4 cm or 20 x 30 x 0.2 cm; skimming with a doctor removes the excess resin, and hardening is carried out at 80°C for 1 h, then at 120°C for 2 h and at 170°C for 2 h. After one week of storage at room temperature, test specimens are then milled from the material. The results in table 1 show that a significantly higher heat resistance is found in the inventive examples in the absence of free-radical initiators. The heat-deflection temperature of above 150°C (three-point bending with 0.45 MPa outer fiber stress in accordance with DIN EN ISO 75) is remarkable for polyurethane materials. These examples in particular show that it is possible to produce fiber-reinforced pipes, for example in the fiber-winding process. Comparative ex. 2: 99.5 parts of TMPTA and 0.5 part of free-radical initiator 1 are mixed at room temperature and hardened at 80°C for 10 min. An inhomogeneous, brittle polymer with irregular surface is obtained, from which it is impossible to obtain any test specimens. Tg (determined by DSC) is 122°C. The person skilled in the art knows that Tg of a polymer is usually above the heat-deflection temperature. Comparative ex. 2 using the olefin homopolymer produced by a free-radical route therefore has significantly lower heat resistance than the inventive examples. Table 2 [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] Table 2: The starting materials for Ex. 2 and, respectively, comparative ex. 1 are mixed at room temperature; the isocyanate is then added and the mixture is mixed for 60 s in a high-speed mixer (FA Hauschild); the reaction mixture is then cast into a metal mold measuring 20 x 30 x 0.4 cm or 20 x 30 x 0.2 cm; a doctor is used for skimming to remove the excess resin. The reaction mixture is cured at 40°C for 1 hour. Test specimens measuring 4 mm x 80 mm x 10 mm are then punched out for measurement of heat resistance. Some of these test specimens are heat-conditioned in accordance with the data in table 2 before measurement of heat resistance. The results illustrate the reaction profile. In the presence of a free-radical inhibitor, only partial reaction has taken place at temperatures below 80°C. In this state, the reaction product can be stored and is tacky. As a result of higher temperatures > 120°C, the heat-deflection temperature of the inventive example increases significantly by more than 100°C, and only then are the final properties achieved. The heat-deflection temperature of the inventive example with full hardening (160°C) is significantly higher than in comparative example 1 with free-radical initiator (120°C). Table 3 [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] Table 3: Example 3 (with catalyst) exhibits a better heat-deflection temperature together with significantly better impact resistance than example 4 (without catalysts). Table 4 [Image disponible dans le document PDF, Image available in the PDF document] The examples in table 4 show formulations which in particular have good suitability for the vacuum infusion process and, because of the relatively low viscosity of inventive example 5, permit rapid charging of the component. Heat-deflection temperature found is higher than in comparative example 3. Table 5 [Image disponible dans le document PDF, Image available in the PDF document] Table 5: Production of prepreg Production of a laminate (unidirectional pre-impregnated semifinished textile product): The starting materials (table 5) are mixed at room temperature. A metering system is then used to charge the reaction mixture continuously at room temperature into an open bath. The pre-impregnation method used is based on the wet winding process. A total of 42 rovings (external take-off, use of yarn brakes for each roving) Tex 2400 are first passed through a perforated metal sheet and then passed continuously through the impregnation bath. The scrapers integrated into the impregnation device remove the excess resin by skimming, and this can run back into the bath; this avoids any dripping of resin from the impregnated rovings. The impregnated rovings are then passed through a metallic bore measuring 5.5 x 0.2 cm, laid between release paper, and hardened at 80°C. After passage through the heating unit, the resultant unidirectional prepreg, width 5.5 cm, can be wound up on a reel. The prepreg is a tack-free solid mass, and is amenable to manual change of shape, without use of tooling. The prepregs thus produced are unwound and cut into a plurality of sections of length 30 cm. Two plies of prepreg are laid up into the mold with fiber orientation 0° and 90°. The mold is then closed and heated first to 120°C for 1 h and then to 150°C for 1 h. A hard three- dimensional component, no longer amenable to manual change of shape, can then be removed. Fiber content by volume is 60%. Polyol 1: Propoxylated / ethoxylated mixture of sucrose and diethylene glycol, OHN 400 and functionality 4.5, viscosity 3000 mPas [25°C] Polyol 2: branched fatty acid ester, OHN 173, viscosity 3400 mPas [25°C] Polyol 3: non-NCO-reactive fatty acid ester, viscosity 7 mPas [25°C] Polyol 4: Propoxylated mixture of sucrose and glycerol, OHN 490 and functionality 4.4, viscosity 8450 mPas [25°C] Polyol 5: Propoxylated glycerol OHN 805, viscosity 1275 mPas [25°C] Polyol 6: Propoxylated glycerol, OHN 400, viscosity 375 mPas [25°C] Polyol 7: Propoxylated propylene glycol, OHN 248, viscosity 75 mPas [25°C] Polyol 8: Castor oil, OHN 160, viscosity 1025 mPas [25°C] Polyol 9: Cationically propoxylated glycerol, OHN 555, viscosity 690 mPas [25°C] TMPTA: Trimethylolpropane triacrylate Catalyst 1: 40% solution of potassium acetate in DPG Free-radical initiator 1: Benzoyl peroxide Free-radical inhibitor 1: Phenothianzine Antifoam 1: Efka SI 2008, BASF SE 5 Antifoam 2: Efka SI 2723, BASF SE Isocyanate 11:1 mixture of a prepolymer based on 4,4'-MDI, dipropylene glycol / polypropylene glycol and carbodiimide-modified 4,4'-MDI with 26% NCO content Isocyanate 2: 1:1 mixture of polymer MDI and a 1:1 mixture of 2,4'-MDI and 4,4'-MDI with 32.5% NCO content Tests: Viscosity in accordance with DIN 53019-1 to 3 Shore D hardness test in accordance with DIN ISO 7619-1 3-point bending test in accordance with DIN EN ISO 178 Tensile strength in accordance with DIN EN ISO 527 Charpy impact resistance (flatwise) in accordance with DIN EN ISO 179-1 / 1fU Heat-deflection temperature: HDT-B-f, flatwise three-point bending at 0.45 MPa outer fiber stress in accordance with DIN EN ISO 75

Claims

1. A process for the production of a polyurethane material with heat-deflection tem- perature of at least 130° C in three-point bending with 0.45 MPa outer fiber stress in accordance with DIN EN ISO 75, where a) di- and / or polyisocyanates, b) compounds having hydrogen atoms reactive toward isocyanate groups, where these comprise no compounds having carbon-carbon double bonds, c) compounds comprising at least one carbon-carbon double bond, d) optionally catalyst that accelerates the urethane reaction, and e) optionally other auxiliaries and additives, are mixed to give a reaction mixture and are hardened at temperatures above 120° C, where the compounds b) having hydrogen atoms reactive toward isocyanate have, per molecule, an average of at least 1.5 hydrogen groups reactive toward isocyanate and the compounds (c) having carbon-carbon double bond comprise compounds (c1) of this type which have at least one carbon-carbon double bond and at least one group that is an isocyanate group or that is reactive toward isocyanate and / or (c2) which have at least two carbon-carbon double bonds, and where the reaction mixture has been stabilized by addition of free-radical inhibitor to the extent that when the components are mixed at room temperature and the mixture is injected into a metal mold with the dimensions 20 cm x 30 cm x 0.4 cm controlled to a temperature of 80° C and is demolded after 60 minutes and cooled to room temperature the heat-deflection temperature of the resultant polyure- thane material in three-point bending with 0.45 MPa outer fiber stress in accord- ance with DIN EN ISO 75 is at least 25° C lower than the heat-deflection temper- ature of the identically produced polyurethane material which is heat-conditioned for a further 120 minutes at 150° C in an oven after the production process and then is cooled to room temperature.

2. The process according to claim 1, wherein the impact resistance of the polyure- thane material in accordance with DIN EN ISO 179 − 1 / 1 179-1 / 1 fU is above 25 kJ / m 2 25 \text{ kJ / m}^2 .

3. The process according to claim 1 or 2, wherein the equivalence ratio of isocyanate groups of the di- and / or polyisocyanates (a) to the hydrogen atoms reactive toward isocyanate is 0.7 to 1.4.

4. The process according to any one of claims 1 to 3, wherein the proportion of the entirety of the compounds (c1) and (c2), based on the total quantity of compounds (c), is 5 to 100 mol%.

5. The process according to any one of claims 1 to 4, wherein the molar mass of the compound (c) is below 1000 g / mol.

6. The process according to any one of claims 1 to 5, wherein the compounds (c1) and (c2) have, based on the carbon-carbon double bonds, 60 to 100% of terminal car- bon-carbon double bonds.

7. The process according to any one of claims 1 to 6, wherein the di- and / or polyiso- cyanates (a) comprise at least 50 mol% of isocyanates with functionality of 2.

8. The process according to any one of claims 1 to 7, wherein di- or polyisocyanates (a) used comprise 2,4'-MDI, 4,4'-MDI or a mixture of these components, optionally also with MDI homologs having a larger number of rings.

9. The process according to any one of claims 1 to 8, wherein the reaction mixture comprises 0.001 to 1.0% by weight of free-radical inhibitors.

10. The process according to any one of claims 1 to 9, wherein the reaction mixture comprises basic catalysts.

11. The process according to any one of claims 1 to 10, wherein the proportion of the compounds (c) having carbon-carbon double bond, based on the total weight of components (a) to (e), is 10 to 70% by weight.

12. The process according to any one of claims 1 to 11, wherein the compounds (b) having hydrogen atoms reactive toward isocyanate groups, where these comprise no compounds having carbon-carbon double bonds, comprise higher-molecular- weight compounds having hydrogen atoms reactive toward isocyanate and molar mass of 300 g / mol and above, and the higher-molecular-weight compounds having groups reactive toward isocyanate comprise at least one hydroxy-functional com- pound having hydrophobic groups.

13. The process according to any one of claims 1 to 12, wherein the reaction of the re- action mixture is conducted in a first stage for at least 10 minutes at temperatures below 120° C and then the mixture is hardened at temperatures above 150° C.

14. The process according to any one of claims 1 to 13, wherein the polyurethane ma- terial is a polyurethane fiber-composite material, where the reaction mixture is used to wet a fiber material and then the mixture is hardened to give the polyure- thane fiber-composite material.

15. A polyurethane material obtained by a process according to any one of claims 1 to