MXPA96002910A - Production of rigid foams based on isocian - Google Patents

Abstract

The present invention relates to a process for producing rigid foams based on isocyanate, comprising reacting: a) organic polyisocyanates, modified organic polyisocyanates or mixtures of organic polyisocyanates and organic polyisocyanates modified with b) at least one compound containing at least two atoms of reactive hydrogen and c) optionally cross-linking chain extenders or mixtures of chain extenders and crosslinking agents, in the presence of: d) blowing agents or swelling agents, and e) catalysts, wherein the blowing agent (d) it comprises a mixture of at least one low-boiling hydrocarbon having from 3 to 7 carbon atoms and a low molecular weight monohydric alcohol containing a primary or secondary hydroxyl group and having from 1 to 4 carbon atoms

Description

"PRODUCTION OF RIGID FOAMS BASED ON ISOCYANATE" The invention relates to a process for producing rigid foams based on isocyanate, wherein the swelling agent used is a mixture of at least one hydrocarbon of low boiling temperature having from 3 to 7 carbon atoms, low monohydric alcohols molecular weight containing primary or secondary hydroxyl groups and having 1 to 4 carbon atoms and, if desired, the carbon dioxide formed from water and isocyanate, the blowing agent mixture used in accordance with this process and the use of the resulting rigid foams as an insulation material. Rigid isocyanate-based foams, in particular polyurethane and isocyanurate foams, have been known for a long time and are mainly used for heat or cold insulation, eg, in refrigeration appliances, in buildings, in hot water tanks and long-distance heating pipes. Even recently, the swelling agents used to produce these foams have been chlorofluorocarbons (CFCs), particularly, trichlorofluoromethane. These CFCs, due to their destructive action on the ozone layer of the globe, have to be replaced by materials that do not have this ozone depletion potential (ODP) and have a global warming potential (GWP) that is as low as possible. Furthermore, it is to be expected that, for at least a few years, only halogen-free blowing agents or mixtures of the blowing agent will be permitted. Because of these reasons, hydrocarbons have been proposed as the stool agents of the future. The hydrocarbons which have a prominent role are the pentane isomers which, due to their relatively low boiling temperatures, are very suitable as swelling agents for producing rigid foams based on isocyanate. It has been found that cyclopentane provides, compared to n- and iso-pentane, foams having a lower thermal conductivity (EP-A-0 421 269) and, therefore, cyclopentane or its mixtures with temperature materials of boiling below 35 ° C represent, until now, the best variants of the halogen-free swelling agent. Cyclohexane is also proposed in EP-A-0 421 269 as a swelling agent similar to cyclopentane. In the last two years, cyclopentane has already been established in the European refrigeration appliances industry. However, due to cost reasons and due to the somewhat more intense swelling action, n-pentane or iso-pentane and other low boiling point hydrocarbons are also used as swelling agents, even when these provide values of thermal conductivity lower than cyclopentane. Even when the use of these hydrocarbons, including cyclopentane, provides foams that are very usable for insulation purposes, these foams still have disadvantages compared to products blown by means of CFC, particularly with respect to the flow properties of the forming mixture. of foam. The use of polar compounds of low boiling temperature or even relatively high boiling temperature mixed with the cyclopentane, for example, formic esters or acetic esters, ketones or low boiling point esters as described in US Patent Number A- 5 336 696, does not lead to an improved flowability of blowing action but due to the intense plasticizing effects of the materials claimed in that invention in the rigid foam framework of isocyanate adducts, it provides catastrophic shrinkage phenomena, especially in the case of foams in the industrially important density scale of less than 50 grams per cubic meter. Monohydric alcohols have not yet been used in combination with halogen-free hydrocarbons as auxiliaries to improve the swelling action and flow behavior, and the production of rigid foams based on isocyanate. Among the monohydric alcohols, methanol has only been used as a constituent of the specific catalysts to produce carbodiimide foams resistant to high temperature (DT-A-253 029, US-A-3 887 501, US-A-4 029 611, EP-A-2281, US-A-3 922 238) or a polyamide foam (U.S. Patent No. A-3 620 987) from isocyanates. It is also known that low molecular weight alcohols can be introduced into the isocyanate with the prepolymer formation occurring by reaction to provide the urethane (e.g., DE-A-43 41 973). This improves the compatibility of the polyol component with the isocyanate component. Since in this process the alcohol has already been chemically retained in a quantitative way to the isocyanate in the urethane form prior to the foam-forming reaction, no swelling action is to be expected.

GB-A-2 271 996 discloses the combination of dibutyl phthalate and ethanol in a molar ratio of 1: 1.5 to 1: 4 as the swelling agent, for the production of a waste foam from paper and isocyanate industry. Details of quality parameters are not provided. In rigid foams of normal quality based on isocyanate, it is known that the presence of only small amounts of the plasticizer results in intense unacceptable shrinkage phenomena. This mixture, therefore, is unusable as a swelling agent for normal rigid foams based on isocyanate. EP-A-0 483 479 discloses the use of tertiary alcohols, in particular tertiary butanol in combination with water as the swelling agent. The object is the production of rigid integral foams having a pore-free, densified, smooth surface in the absence of physically acting swelling agents. The tertiary butanol here reacts with the isocyanate groups with the removal of carbon dioxide to provide butene. The tertiary butanol, therefore, acts as a chemical swelling agent. The tertiary alcohols thus differ from the other monohydric alcohols which not only have a physical swelling action, but can also be incorporated in the foam framework by means of their hydroxyl groups and can influence the properties. Various mixtures of HCFCs (at least one hydrogen in the chlorofluorocarbon compound molecule) or chlorinated hydrocarbons with low molecular weight monohydric alcohols are also claimed as cleaners, for which the use of a swelling agent is sometimes mentioned as well. rigid polyurethane foams (EP-A-0 379 268, US-A-5 039 442, WO 91/18966, WO 92/06800, DD 211 121). Among these documents, only WO 92/06800 and DD 211 121 describe examples for producing rigid polyurethane foams using alcohol / chlorofluoro compounds in admixture, as the swelling agent. In addition, DD 211 121 claims only the joint addition of water and alcohol in a molar ratio greater than 4 for densities above 160 kilograms per cubic meter. The concentration of alcohol in the total foam-forming composition is always less than 0.5 percent. Under these conditions, alcohol has no swelling action other than that of water. The fact that the relatively high boiling temperature alcohols described in WO 92/06800 has any swelling action is attributed to the specific interactions between alcohol and CFC (azeotroping). However, these hydrocarbons containing halogen, in the future will not be allowed as swelling agents (as mentioned above) or even in combination with alcohols. The use of low molecular weight alcohols in admixture with halogen-containing swelling agents is by no means possible to deduce the use of mixtures of alcohols and halogen-free hydrocarbons, since the physical-chemical structure of the halogen-free hydrocarbons differs considerably from that of halogen-containing carbon compounds. In this way, for example, the dipole moments of the CF and C-Cl bonds are 1.5 and 1.7 debye, respectively, but the dipole moment of the CH bond is only 0.2 debye (Rudolf Brdicka, Grundlagen der Physikalischen Chemie, fourth edition, VEB Deutscher Verlag der Wissenschaften, Berlin 1963, page 855) and, correspondingly, completely different interactions between alcohols and halogen-containing carbon compounds are expected, in comparison with alcohols and halogen-free hydrocarbons. It is an object of the present invention to produce rigid isocyanate-based foams, while greatly minimizing the manifested disadvantages that occur when using previously described swelling agents or swelling agent mixtures. In particular, the swelling action and the flow behavior in the foam-forming reaction mixture should be considerably improved. It has been found that this object is achieved by using low molecular weight monohydric alcohols containing primary or secondary hydroxyl groups together with cyclopentane and / or other low boiling point hydrocarbons if desired, in combination with water, as the swelling agent. The invention accordingly provides a process for producing rigid foams based on isocyanate by reacting a) organic polyisocyanates and / or organic polyisocyanates modified with b) at least one relatively high molecular weight compound containing at least two reactive hydrogen atoms and , if desired, c) low molecular weight chain extension agents and / or crosslinking agents in the presence of d) swelling agents, e) catalyzed and, if desired, f) auxiliary and / or additional additives, where the swelling agent used is a mixture of at least one low boiling point hydrocarbon having from 3 to 7 carbon atoms and low molecular weight monohydric alcohols containing primary or secondary hydroxyl groups and having from 1 to 4 atoms carbon, if desired, in combination with the carbon dioxide formed of water and isocyanate. The invention also provides a mixture of the swelling agent for the production of rigid polyisocyanate based foams provides means for the use of rigid foams as an insulating material. The use of monohydric alcohols in combination with the halogen-free hydrocarbons surprisingly provides a considerable additional swelling action combined with considerably improved flow of the foam-forming mixture without the above-described disadvantages associated with the use of increased amounts of hydrocarbons, increased amounts of water or low boiling temperature esters, ketones and ethers. Accordingly, the prevailing opinion so far is that the monofunctional materials active with hydrogen deteriorate both the processing properties, such as the curing process and the final properties of the rigid foams based on isocyanate interfering in the crosslinking reaction. Therefore, it is totally surprising that simple measures based on modifications of current formulations not only counteract these disadvantages, but in most cases lead to improvements in properties. The swelling agent mixture to be used according to the present invention preferably contains the low boiling point hydrocarbons having from 3 to 7 carbon atoms in an amount from 0.1 percent to 12 mass percent, particularly, preferably from 4 percent to 8 percent by mass, and preferably contains low molecular weight monohydric alcohols containing primary or secondary hydroxyl groups and having from 1 to 4 carbon atoms in an amount of 0.1 percent a 6 percent by mass, particularly preferably from 2 percent to 4 percent by mass, based in each case on the total amount of the foam. As low boiling point hydrocarbons having from 3 to 7 carbon atoms preference is given to the use of cyclopentane, n-pentane and isopentane. These hydrocarbons can be used alone or mixed with one another. Suitable low molecular weight monohydric alcohols containing primary or secondary hydroxyl groups and having 1 to 4 carbon atoms, in particular are methanol, ethanol, n-propanol, isopropanol and the isomers of butanol, except tertiary butanol. These alcohols can be used alone or mixed with one another. Rigid isocyanate-based foams are produced by reacting a) organic polyisocyanates and / or organic polyisocyanates modified with b) at least one relatively high molecular weight compound containing at least two reactive hydrogen atoms and, if desired, c) low molecular weight chain extension agents and / or crosslinking agents, in the presence of d) the mixture of the swelling agent of the present invention, and e) catalysts and, if desired, f) auxiliaries and / or additional additives customary in a manner known per se. To produce the rigid isocyanate-based foams by the process of the present invention, use is made, with the exception of the swelling agents (d), of forming components known per se about which the following details can be provided. a) Suitable organic polyisocyanates are the polyfunctional, aliphatic, cycloaliphatic, araliphatic and preferably aromatic isocyanates, known per se. Specific examples are: alkylene diisocyanates having from 4 to 12 carbon atoms in the alkylene radical, for example, 1,2-dodecane diisocyanate, 1,4-di-2-ethyl-tetramethylene diisocyanate, 1,5-diisocyanate 2-methylpentamethylene, 1,4-tetramethylene diisocyanate and preferably 1,6-hexamethylene diisocyanate; cycloaliphatic diisocyanates such as 1,3- and 1,4-cydohexanediisocyanate and any of the mixtures of these isomers, l-isocyanato-3, 3, 5-trimethyl-5-isocyanato-methylcyclohexane (isophorone diisocyanate), 2, 4- and 2,6-hexahydrotolylene diisocyanate and the corresponding isomer mixtures, 4,4'-, 2,2'- and 2,4'-diisocyanate of dicyclohexylmethane and the corresponding isomer mixtures and preferably aromatic diisocyanates and polyisocyanates such as 2,4- and 2,6-toluene diisocyanate and the corresponding isomer mixtures, 4,4'-, 2,4'- and 2, 2 * diphenylmethane diisocyanate and the corresponding isomer mixtures, mixtures of 4,4'- and 2,4'-diphenylmethane diisocyanates, polyphenylenepolymethylene polyisocyanates, mixtures of 4,4'-, 2,4'- and 2,2'-diphenylmethane diisocyanates and polyphenylenepolymethylene polyisocyanates (crude MDI) and mixtures of crude MDI and toluene diisocyanates. The organic diisocyanates and polyisocyanates can be used individually or in the form of their mixtures. The modified polyfunctional isocyanates are also frequently used, ie the products obtained by chemical reaction of the diisocyanates and / or organic polyisocyanates. Examples which may be mentioned are diisocyanates and / or polyisocyanates containing ester, urea, biuret, allophanate, carbodiimide, isocyanurate, uretdione and / or urethane groups. Specific examples are: organic polyisocyanates, preferably aromatics containing urethane groups and having NCO contents from 33.6 percent to 15 percent by weight, preferably from 31 percent to 21 percent by weight based on total weight , for example, the 4, 4'-diphenylmethane diisocyanate modified with diols, triols, dialkylene glycols, trialkylene glycols or low molecular weight polyoxyalkylene glycols, having molecular weights up to 6000, in particular having molecular weights up to 1500, mixtures of 4,4'- and 2,4'-modified diphenylmethane-diisocyanate, or modified crude MDI or 2,4- or 2,6-toluene diisocyanate, with examples of dialkylene glycols or polyoxyalkylene glycols that can be used individually as mixtures being : diethylene glycol, dipropylene glycol, polyoxyethylene glycols, polyoxypropylene glycols and polyoxypropylene polyoxyethylene glycols and the corresponding triols and / or tetraols. Also suitable are NCO-containing prepolymers from 25 percent to 3.5 percent by weight, preferably from 21 percent to 14 percent based on the total weight, prepared from polyester polyols and / or preferably polyether polyols that are described below and 4, 4 '-diphenylmethane diisocyanate, mixtures of 2,4'- and 4,4'-diphenylmethane-diisocyanate, 2,4- and / or 2,6-toluene diisocyanates or the crude MDI. Other suitable modified polyisocyanates are the liquid polyisocyanurates containing carbodiimide groups and / or isocyanurate rings and having NCO contents of 33.6 percent to 15 percent by weight, preferably 31 percent to 21 percent by weight, based on in total weight, for example, based on 4,4'-, 2,4'- and / or 2, 2'-diphenylmethane diisocyanate and / or 2,4- and / or 2,6-toluene diisocyanate. The modified polyisocyanates if desired can be mixed with each other or with unmodified organic polyisocyanates, such as 2,4'- and / or 4,4'-diphenylmethane diisocyanate, crude MDI, 2,4- and / or 2, 6-toluene diisocyanate. Polyisocyanates which have been found to be particularly useful are diphenylmethane diisocyanate isomer mixtures or crude MDI having an isomer content of diphenylmethane diisocyanate of 33 percent to 55 percent by mass and polyisocyanate mixtures containing urethane groups and based on diphenylmethane diisocyanate and having an NCO content of 15 percent to 33 percent by mass. b) Appropriate compounds containing at least two hydrogen atoms that are reactive towards the isocyanates are the compounds carrying two or more reactive groups selected from the OH groups, the SH groups, the NH groups, the NH2 groups and the CH acid groups, such as the beta-diketo groups in the molecule. Advantageously use is made of those having a functionality of 2 to 8, preferably 2 to 6 and a molecular weight of 300 to 8000, preferably 400 to 4000. Compounds which have been found to be useful are, for example , polyether polyamines and / or preferably polyols selected from the group consisting of polyether polyols, polyester polyols, polythioether polyols, polyesteramides, hydroxyl-containing polyacetals, hydroxyl-containing aliphatic polycarbonates or mixtures of at least two of the specified polyols. Preference is given to using polyester polyols and / or polyether polyols. The hydroxyl number of the polyhydroxyl compounds is here generally from 100 to 850 and preferably from 200 to 600. Suitable polyester polyols can be prepared, for example, from organic dicarboxylic acids having from 2 to 12 carbon atoms, preferably , aliphatic dicarboxylic acids having from 4 to 6 carbon atoms, and polyhydric alcohols, preferably diols, having from 2 to 12 carbon atoms, preferably from 2 to 6 carbon atoms. Examples of suitable dicarboxylic acids are: succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid and terephthalic acid. The dicarboxylic acids can be used either individually or in admixture with one another. Instead of the free dicarboxylic acids, it is also possible to use the corresponding dicarboxylic acid derivatives, such as dicarboxylic esters of alcohols having from 1 to 4 carbon atoms or dicarboxylic anhydrides. Preference is given to using the dicarboxylic acid mixtures of succinic, glutaric and adipic acid in weight ratios, for example, 20-35: 35-50: 20-32, and in particular adipic acid. Examples of dihydric and polyhydric alcohols, in particular diols, are: ethanediol, diethylene glycol, 1,2- or 1,3-propanediol, dipropylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1, 10-decanodiol, glycerol and trimethylolpropane. Preference is given to the use of ethanediol, diethylene glycol, 1,4-butanediol, 1-5-pentanediol, 1,6-hexanediol or mixtures of at least two of the specified diols, in particular mixtures of 1,4-butanediol, , 5-pentanediol and 1,6-hexanediol. It is also possible to use polyester polyols of lactones, e.g., epsilon-caprolactone or hydroxycarboxylic acids, e.g., omega-hydroxycaproic acid. To prepare the polyester polyols, the polycarboxylic acids, for example aromatic and preferably aliphatic and / or the polyhydric derivatives and alcohols can be polycondensed in the absence of a catalyst, preferably in the presence of esterification catalysts, advantageously in a gas atmosphere inert, such as nitrogen, carbon monoxide, helium, argon, etc. in melting at a temperature of 150 ° to 250 ° C, preferably 180 ° to 220 ° C, if desired under reduced pressure, up to the desired acid number which is advantageously less than 10, preferably less than 2. According to a preferred embodiment, the esterification mixture is polycondensed at the above mentioned temperatures up to an acid number of 80 to 30, preferably of 40 to 30 at atmospheric pressure and subsequently, under a pressure of less than 500 mbar, of preference of 50 to 150 mbar. Suitable esterification catalysts are, for example, catalysts of iron, cadmium, cobalt, lead, zinc, antimony, magnesium, titanium and tin in the form of metals, metal oxides or metal salts. However, polycondensation can also be carried out in the liquid phase in the presence of diluents and / or retention agents, such as benzene, toluene, xylene or chlorobenzene to azeotropically distill the condensation water. To prepare polyester polyols, the organic polycarboxylic acids and / or the polyhydric derivatives and alcohols are advantageously polycondensed in a molar ratio of 1: 1-1.8, preferably 1: 1.05-1.2. The polyester polyols obtained preferably have a functionality of 2 to 4, and in particular, of 2 to 3, and a molecular weight of 800 to 3000, preferably, 350 to 2000 and, in particular, of 400 to 600.

However, particularly preferred polyols are polyether polyols which are prepared by known methods, for example, by anionic polymerization using alkali metal hydroxides, e.g., sodium or potassium hydroxide, or alkali metal alkoxides, v. g., sodium methoxide, sodium or potassium ethoxide or potassium isopropoxide, as catalysts with the addition of at least one initiator molecule containing from 2 to 8, preferably from 2 to 6, reactive hydrogen atoms in linked form cationic polymerization using Lewis acids, such as antimony pentachloride, boron fluoride etherate, etc. or bleaching earth as catalysts of one or more alkylene oxides having from 2 to 4 carbon atoms in the alkylene radical. Suitable alkylene oxides are, for example, tetrahydrofuran, 1,3-propylene oxide, 1,2- or 2,3-butylene oxide, styrene oxide and, preferably, ethylene oxide and 1-oxide. 2-propylene. The alkylene oxides can be used individually alternatively in succession or as mixtures. Suitable initiator molecules, for example, are: water, organic dicarboxylic acids such as succinic acid, adipic acid, phthalic acid and terephthalic acid, aliphatic and aromatic diamines, nonalkylated, N-monoalkylated diamines, N, N- and N, N -alkylated having 1 to 4 carbon atoms in the alkyl radical, for example, unalkylated ethylenediamine, monoalkylated, dialkylated, diethylenetriamine, triethylenetetramine, 1,3-propylenediamine, 1,3- or 1,4-butylenediamine, 1,2-, 1,3-, 1,4-, 1,5- and 1,6-hexamethylenediamine, phenylenediamine, 2,3-, 2,4- and 2,6-tolylenediamine and 4,4'-, 2,4'- and 2,3'-diaminodiphenylmethane. Other suitable starter molecules are: alkanolamines, such as ethanolamine, N-methylethanolamine and N-ethylethanolamine, dialkanolamines, such as diethanolamine, N-methyldiethanolamine and N-ethyldiethanolamine and trialkanolamines, such as triethanolamine and ammonia. Preference is given to using the polyhydric alcohols, in particular the dihydric and / or trihydric alcohols, such as ethanediol, 1,2-propanediol and 1,3-propanediol, diethylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol , glycerol, trimethylolpropane, pentaerythritol, sorbitol and sucrose. The polyether polyols, preferably polyoxypropylene and polyoxypropylene polyoxyethylene polyols have a functionality of preferably from 2 to 6, and in particular from 2 to 4 and molecular weights from 300 to 8000, preferably from 400 to 1500 and in particular from 420 to 1100, and the appropriate polyoxytetramethylene glycols have a molecular weight of up to about 3500. Other suitable polyether polyols are polymer modified polyether polyols, preferably graft polyether polyols, in particular those based on styrene and / or acrylonitrile which are prepared by the in situ polymerization of acrylonitrile, styrene, preferably mixtures of styrene and acrylonitrile, for example, in a weight ratio of 90:10 to 10:90, preferably from 70:30 to 30:70, Advantageously, the polyether polyols mentioned above by a method similar to that provided in the German patents numbers 11 11 394, 12 22 669 (Norteamer patent) number 3 304 273, number 3 383 351, number 3 523 093) number 11 52 536 (United Kingdom patent number 10 40 452) and number 11 52 537 (United Kingdom patent number 98 618) and also polyol dispersions of polyethers containing as the dispersed phase usually in an amount of 1 percent to 50 percent by weight, preferably 2 percent to 25 percent by weight: for example, polyureas, polyhydrazides, polyurethanes containing linked tertiary amino groups and / or melamine and are described, for example, in EP-B-011 752 (U.S. Patent No. 4 304 708), U.S. Patent No. A-4 374 209 and DE-A-32 31 497.

Like polyester polyols, polyether polyols can be used individually or in the form of mixtures. They can also be mixed with graft polyether polyols or graft polyester polyols or with hydroxyl-containing polyesteramides, polyacetals, polycarbonates and / or polyether polyamines. Aryopylated hydroxyl-containing polyacetals are, for example, compounds that can be prepared from glycols, for example, diethylene glycol, triethylene glycol, 4,4'-dihydroxyethoxydiphenyldimethylmethane and hexanediol and formaldehyde. Suitable polyacetals can also be prepared by polymerization of cyclic acetals. Suitable hydroxyl-containing polycarbonates are those of a type known per se which can be prepared, for example, by reacting diols, such as 1,3-propanediol, 1,4-butanediol and / or 1,6-hexanediol, diethylene glycol, triethylene glycol or tetraethylene glycol with diaryl carbonates, v.gr, diphenyl carbonate or phosgene. Polyesteramides include, for example, mainly linear condensates obtained from polybasic, saturated and / or unsaturated carboxylic acids or their saturated and / or unsaturated polyfunctional anhydrides and aminoalcohols or mixtures of polyhydric alcohols and amino alcohols and / or polyamines. Suitable polyether polyamines can be prepared from the aforementioned polyether polyols by known methods. Examples which may be mentioned are the cyanoalkylation of polyoxyalkylene polyols and the subsequent hydrogenation of the formed nitrile (US Pat. No. 3 267 050) or the partial or complete amination of polyoxyalkylene polyols with amines or ammonia in the presence of hydrogen and catalysts (DE 12 15). 373). c) Isocyanate-based rigid foams can be produced with or without the concomitant use of chain extension agents and / or cross-linking agents. However, the addition of chain extension agents, crosslinking agents or, if desired, mixtures thereof, may be advantageous for modifying the mechanical properties, e.g., hardness. The chain extension agents and / or the crosslinking agents used are diols and / or triols having molecular weights of less than 400, preferably from 60 to 300. Examples of appropriate chain extension agents and / or agents of crosslinking are the aliphatic, cycloaliphatic and / or araliphatic diols having from 2 to 14, preferably from 4 to 10 carbon atoms, for example, ethylene glycol, 1,3-propanediol, 1,10-decanediol, or-, m- or p-dihydroxycyclohexane, diethylene glycol, dipropylene glycol, and preferably 1,4-butanediol, 1,6-hexanediol and bis (2-hydroxyethyl) hydroquinone, triols such as 1,2,4- and 1,3,5-trihydroxycyclohexane, glycerol and trimethylolpropane, and the polyalkylene oxides containing low molecular weight hydroxyl based on the ethylene oxide and / or the 1,2-propylene oxide and the aforementioned diols and / or triols as the initiator molecules. If the chain extension agents are used as crosslinking agents or mixtures thereof to produce the rigid foams based on isocyanate, these are advantageously used in an amount of 0 percent to 20 percent by weight, preferably 2 percent by weight. percent to 8 weight percent based on the weight of the polyol compound (b). d) The swelling agent (d) used in the above-described swelling agent mixture according to the present invention, comprising at least one low boiling point hydrocarbon having from 3 to 7 carbon atoms and low monohydric alcohols. molecular weight having 1 to 4 carbon atoms. It is advantageously introduced into the polyol component consisting of the forming components (b), (e) and if (c) and (f) is used. However, it is also possible to supply in a regulated manner a mixture of the low boiling point hydrocarbons and the low molecular weight monoohydric alcohols separately from the polyol component in the mixing head of a foam forming machine. Also, the low molecular weight monohydric alcohol or the mixture of alcohols can be supplied regulated only to the mixing head using this technique, while the remaining swelling agent has been previously dissolved in the polyol component or vice versa, and the low boiling point hydrocarbons can be fed to the mixing head separately from a mixture of the polyol component and the low molecular weight monohydric alcohols. The swelling agent mixture of the present invention can be used alone or preferably in combination with water. e) The catalysts (e) for producing the rigid isocyanate-based foams are in particular the compounds which intensively accelerate the reaction of the compounds of component (b) and if used (c) which contains reactive hydrogen atoms, in particular , hydroxyl groups, with the modified or unmodified organic polyisocyanates (a). However, the isocyanate groups can also be reacted with one another by means of suitable catalysts (e) with isocyanurate structures which are preferably formed in addition to the isocyanate adducts (a) with the compounds having groups (b) active to hydrogen. The catalysts used, therefore, in particular, are those materials that accelerate the reactions of isocyanates, in particular, urethane, urea and isocyanurate formation. For this purpose preference is given to tertiary amines, tin and bismuth compounds, alkali metal and alkaline earth metal carboxylates, quaternary ammonium salts, s-hexahydrotriazines and tris (dialkylaminomethyl) phenols. Examples of suitable catalysts are organic metal compounds, preferably organic tin compounds, such as tin (II) salts of organic carboxylic acids, e.g., tin (II) acetate, tin octoate ( II), tin (II) ethylhexanoate and tin (II) laurate, and dialkyltin (IV) salts of organic carboxylic acids, e.g., dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate and diacetate dioctyltin. The organic metal compounds are used alone or preferably in combination with intensely basic amines. Examples which may be mentioned amidines, such as 2,3-dimethyl-3,4,5,6-tetrahydropyrimidine, tertiary amines, such as triethylamine, tributylamine, dimethylbenzylamine, N-methylmorpholine, N-ethylformoline, N-cyclohexylmorpholine, N, N, N ', N'-tetramethylethylenediamine, N, N, N', N * -tetramethylbutanediamine, N, N, N ', N' -tetramethylhexane-1,6-diamine, pentamethyldiethylenetriamine, bis (dimethylaminoethyl) ether, bis (dimethylaminopropyl) urea, dimethylpiperazine, 1,2-dimethylimidazole, 1-azabicyclo [3.3.0] octane and preferably 1,4-diazabicyclo [2.2.2] octane, the alkanolamine compounds, such as triethanolamine, triisopropanolamine, N -metildietanolamine and N-ethyldiethanolamine and dimethylethanolamine. Other suitable catalysts are: tris (dialkylaminoalkyl) -s-hexahydrotriazines, in particular, tris (N, N-dimethylaminopropyl) -s-hexahydrotriazine, tetraalkylammonium hydroxides, such as tetramethylammonium hydroxide, alkali metal hydroxides, such as sodium hydroxide and alkali metal alkoxides, such as sodium methoxide and potassium isopropoxide and also alkali metal salts of long chain fatty acids having 10 to 20 carbon atoms and, if desired, side OH groups. Preference is given to the use of 0.001 percent to 5 percent by weight, in particular from 0.05 percent to 2 percent in - 21 weight of a catalyst or combination of catalysts based on the weight of component (b). f) If desired it is also possible to incorporate auxiliaries and / or additives (f) in the reaction mixture to produce the rigid foams based on isocyanate. Examples that may be mentioned are surfactants, foam stabilizers, cell regulators, flame retardants, fillers or fillers, dyes, pigments, hydrolysis inhibitors, and fungistatic and bacteriostatic substances. Suitable surfactants are, for example, compounds which serve to assist the homogenization of the starting materials and may also be suitable for regulating the cell structure of plastics. Examples which may be mentioned are emulsifiers, such as the sodium salts of castor oil sulfates or fatty acids and also amine salts of fatty acids, eg diethylammonium oleate, diethylammonium stearate, diethanolammonium ricinoleate salts of sulfonic acids, e.g., alkali metal or ammonium salts of dodecylbenzene or dinaphthylmethane-disulfonic acid and ricinoleic acid; foam stabilizers, such as siloxane-oxyalkylene copolymers and other organopolysiloxanes, ethoxylated alkylphenols, ethoxylated fatty alcohols, paraffin oils, castor oil or ricinoleic esters, turkey red oil and peanut oil and cell regulators, such as paraffins , fatty alcohols and dimethylpolysiloxanes. Also suitable for improving the emulsifying action, the structure of the cell and / or for stabilizing the foam are the above-described oligomeric acrylates having polyoxyalkylene and fluoroalkane radicals as the secondary groups. The surface-active substances are usually used in amounts of 0.01 to 5 parts by weight based on 100 parts by weight of component (b). As flame retardant agents it is possible to use all materials customary for this application in polyurethane chemistry. The use is predominantly made of halogen and phosphorus compounds, for example, esters of orthophosphoric acid and methanphosphonic acid, e.g., tris (2-chloropropyl) phosphate or diethyl bis (2-hydroxyethyl) aminoethyl-phosphonate. Since the rigid isocyanate-based foam will in the future be produced using only halogen-free additives, these flame retardant agents must also be free of halogen. The substances suitable for this purpose are, for example, phosphoric acid derivatives, phosphorous acid or phosphonic acid which are reactive towards the isocyanate if desired in combination with a non-reactive liquid and / or with halogen-free flame retardant agents. , which comprise organic derivatives of phosphoric acid, phosphonic acid or phosphorous acid or salts of phosphoric acid and other materials that help the flame retardant action, for example, starch, cellulose, aluminum hydroxide, etc. The use according to the present invention of halogen-free alcohols and hydrocarbons, such as swelling agents (f) avoids the use of unnecessarily high amounts of hydrogen and, therefore, makes an indirect contribution to reducing flammability. In general, it has been found to be advantageous to use from 5 parts to 50 parts by weight, preferably from 5 parts to 25 parts by weight of the flame retardant agents specified per 100 parts by weight of component (b). For the purposes of the present invention, the fillers or fillers, in particular, the fillers or reinforcing fillers, are the customary organic and inorganic fillers or fillers, reinforcers, weighting agents, agents for improving the performance of abrasion in paints, coating agents, etc. known per se. Specific examples are: inorganic fillers or fillers, such as siliceous minerals, for example, sheet silicates, such as antigorite, serpentine, furnace, amphibole, chrysotile, talc; metal oxides, for example, kaolin, aluminum oxides, titanium oxides and iron oxides, metal salts, for example, clay, barite and inorganic pigments, such as cadmium sulfide, zinc sulphide and also glass, etc. Preference is given to using kaolin (China clay), aluminum silicate and co-precipitates of barium sulfate and aluminum silicate, and also natural and synthetic fibrous minerals, such as wollastonite, metal and, in particular, glass fibers of various lengths that can be coated if desired. Examples of suitable organic fillers or fillers are: starch, carbon, melamine, rosin, cyclopentadienyl resins, graft polymers, and also cellulose fibers, polyamide, polyacrylonitrile, polyurethane, polyester fibers based on aromatic dicarboxylic esters and / or aliphatics and, in particular, carbon fibers. The inorganic and organic fillers can be used individually or as mixtures and are advantageously incorporated into the reaction mixture in amounts of 0.5 percent to 50 percent by weight, preferably 1 percent to 40 percent by weight based on the weight of the components (a) to (c) even though the content of the mats, non-woven and woven fabrics of natural and synthetic fibers can reach values up to 80 percent. Details of the aforementioned and additional starting materials can be found in the specialized literature, for example, the monograph by HJ Saunders and KC Frisch "High Polymers", volume XVI, Polyurethanes, parts 1 and 2, Interscience Publishers of 1962 or 1964, or Kunststoffhandbuch previously mentioned, Polyurethane, volume VII, Cari Hanser Verlag, Munich, Vienna, la., 2nd. and 3rd. editions of 1966, 1983 and 1993. To produce the rigid isocyanate-based foams, the modified organic and / or organic polyisocyanates, the relatively high molecular weight compounds having at least two reactive hydrogen atoms (b) and if desired, the chain extension agents and / or the crosslinking agents (c) are reacted in amounts such that the equivalence ratio of the NCO groups of the polyisocyanates (a) to the sum of the reactive hydrogen atoms of component (b) and, if used, (c), is from 0.85 to 1.75: 1, preferably from 1.0 to 1.3: 1 and, in particular, from 1.1 to 1.2: 1. If the rigid isocyanate-based foams contain at least certain bound isocyanurate groups, a ratio of the NCO groups of the polyisocyanates (a) to the sum of the reactive hydrogen atoms of component (b) and, if used , (c), from 1.5 to 60: 1, preferably from 3 to 8: 1, is the one used. Rigid isocyanate-based foams are advantageously produced by a one-step process, for example, by means of the high-pressure or low-pressure technique in open or closed molds, for example, in metal molds. It has been found to be particularly advantageous to use the two component process and combine the forming components (b), (d), (e) and, if used, (c) and (f), in the component (A) and using the organic polyisocyanates, modified polyisocyanates (a) or mixtures of the polyisocyanates and, if desired, the swelling agent (d). ) as component (B). The starting components are mixed at a temperature of 15 ° to 90 ° C, preferably 20 ° to 60 ° C and, in particular, 20 ° to 35 ° C and introduced into the open mold or, if desired, they are introduced under increased pressure in the closed mold. The mixing can be carried out mechanically by means of an agitator or a stirring screw. The temperature of the mold is advantageously from 20 ° to 110 ° C, preferably from 30 ° to 60 ° C and, in particular, from 45 ° to 50 ° C. In closed molds, it is also possible to use more foam-forming reaction mixtures than necessary to fill the mold completely. This then provides consolidated foams. Another variant of foam production can also be used in a double transport band technique. The rigid polyurethane foams or the molded rigid foams produced by the process of the present invention have a density of 0.02 to 0.75 gram per cubic centimeter, preferably 0.025 to 0.24 gram per cubic centimeter and, in particular, 0.03 to 0.01. gram per cubic centimeter. They are particularly suitable as an insulation material in the construction and refrigeration apparatus sectors, eg, as an intermediate layer for sandwich elements or for filling the housings of refrigerators and chests of the freezer with foam. The following examples illustrate the invention. Examples 1 to 19 show the improved swelling action and the improved flow behavior when mixtures of the swelling agent of the present invention comprising low boiling point alcohols and hydrocarbons are used in comparison with the unique use of low boiling point hydrocarbons. . The other examples serve to show the effects on the other important properties of rigid foams based on isocyanate.

Example 1 (comparison) (pbm = parts in mass) The polyol component consists of: 65.3 pbm of a polyol based on sucrose / propylene oxide, OH number of 440 milligrams of KOH / gram, 13.5 pbm of an amine-based polyol and propylene oxide / ethylene oxide, a OH number of 112 milligrams of KOH per gram, 4.5 pbm of a polyol based on propylene glycol / propylene oxide, OH number of 250 milligrams of KOH per gram, 2.24 pbm of the SR 321 silicone stabilizer (from OSi Specialties), 2.50 pbm of dimethylcyclohexylamine, 1.97 pbm of water and 9.91 pbm of cyclopentane that was mixed intensively with 124 pbm of crude MDI, an NCO content of 31.5 mass percent. The concentrations of the swelling agents based on the total mass of the foam-forming mixture were: water 0.88 mass percent cyclopentane 4.42 mass percent The foam produced had, freely foamed in a foam-forming beaker, a density ( "volumetric density of the vessel to be precipitated") of 31.8 kilograms per cubic meter. The starting time / gel time / expansion time, were in s: 11/49/76.

Hose test: 100 grams of the reaction mixture were placed directly after mixing the components in a continuous hose made of plastic film and having a diameter of 4.5 centimeters. The hose was closed by holding one end and the length of the foam obtained in centimeters was used as a measure of the flowability. A result of 138.8 centimeters was measured. (The results of the hose test are in each case means of 2 or 3 measurements).

Example 2 (according to the present invention) A foam was produced as in Example 1 but with 6 pbm of methanol which were added further to the polyol component.

The concentrations of the swelling agents based on the total mass of the foam-forming mixture were: water 0.86 mass percent cyclopentane 4.31 mass percent methanol 2.61 mass percent The obtained foam had the following properties: Density in the foam forming beaker: 30.2 kilograms per cubic meter. Hose test: 150.3 centimeters. Start time / gel time / expansion time in s: 9/28/45.

Despite a considerably shorter gel time, the foam flowed better in Comparison Example 1.

Example 3 (according to the present invention) A foam was produced as in Example 1, but with 6 pbm of isopropanol which were added further to the polyol component. The concentrations of the swelling agents based on the total mass of the foam-forming mixture were: water 0.86 percent by mass cyclopentane 4.31 percent by mass isopropanol 2.61 percent by mass The obtained foam had the following properties: Density in the foam forming beaker: 30.5 kilograms per cubic meter. Mangera test: 114.4 centimeters.

Example 4 (according to the present invention) A foam was produced as in Example 1, but with 6 pbm of ethanol which was added further to the polyol component.

The concentrations of the swelling agents based on the total mass of the foam-forming mixture were: water 0.86 percent by mass cyclopentane 4.31 percent by mass ethanol 2.61 percent by mass The foam obtained had the following properties: Density in the glass precipitate foam former: 30.3 kilograms per cubic meter. Hose test: 149.5 centimeters.

Example 5 (in accordance with the present invention) A foam was produced as in Example 1, but with 6 pbm of n-butanol added to the polyol component. The concentrations of the swelling agents based on the total mass of the foam-forming mixture were: water 0.86 percent by mass cyclopentane 4.31 percent by mass n-butanol 2.61 percent by mass The foam obtained had the following properties: Density in the Foam forming beaker: 28.0 kilograms per cubic meter. Hose test: 145.3 centimeters.

Example 6 (comparison) The polyol component described in Example 1 was formed in a slightly altered form foam using n-pentane and water. The polyol component consisting of: 63.4 pbm of a polyol based on sucrose / propylene oxide, OH number of 440 milligrams of KOH per gram, 13.11 pbm of an amine-based polyol and propylene oxide / ethylene oxide , OH number of 112 milligrams of KOH per gram, 4.37 pbm of a polyol based on propylene glycol / propylene oxide, OH number of 250 milligrams of KOH per gram, 2.17 pbm of a silicone stabilizer, as described in Example 1, 2.51 pbm of dimethylcyclohexylamine, 1.91 pbm of water and 12.53 pbm of n-pentane, was mixed intensively with 120.7 pbm of crude MDI, NCO content of 31.5 mass percent. The concentrations of the swelling agents based on the total mass of the foam-forming mixture were: water 0.87 mass percent n-pentane 5.69 mass percent The foam obtained and which was freely foamed in the foam forming beaker with a density of 26.8 kilograms per cubic meter. The hose test provided 181.1 centimeters.

Example 7 (in accordance with the present invention) A foam was produced as in Example 6, but with 6 pbm of isopropanol which were added further to the polyol component. The concentrations of the swelling agents based on the total mass of the foam-forming mixture were: water 0.84 mass percent n-pentane 5.53 mass percent isopropanol 2.65 mass percent The foam obtained had the following properties: Density in the pre-foam forming vessel: 26.5 kilograms per cubic meter. Test of maguery: 190.2 centimeters.

In spite of the very intense swelling action of n-pentane itself (greater amount, higher vapor pressure compared to cyclopentane), isopropanol provides an additional swelling effect and a significantly increased flow.

Example 8 (comparison) a foam was produced with Example 6, but with 12.52 pbm of isopentane instead of 12.53 pbm of the n-pentane which was added to the polyol component.

The concentrations of the swelling agents based on the total mass of the foam-forming mixture were: water 0.87 percent isopentane mass 5.69 percent mass The obtained foam had the following properties: Density in the foam forming beaker: 27.0 kilograms per cubic meter. Hose test: 177.6 centimeters.

Example 9 (in accordance with the present invention) A foam was produced as in Example 8 but with 6 pbm of isopropanol which were additionally added to the polyol component. The concentrations of the swelling agents based on the total mass of the foam-forming mixture were: water 0.84 percent by mass isopentane 5.53 percent by mass isopropanol 2.65 percent by mass The foam obtained had the following properties: Density in the glass precipitate foam former: 24.8 kilograms per cubic meter. Hose test: 190.6 centimeters.

Example 10 (comparison) A foam was produced as in Example 6, but with 2.62 pbm of cyclopentane and 2.91 pbm of n-pentane, instead of 12.53 pbm of n-pentane alone that was added to the polyol component. The concentrations of the swelling agents based on the total mass of the foam-forming mixture were: water 0.87 percent by mass cyclopentane 4.36 percent by mass n-pentane 1.32 percent by mass The foam obtained had the following properties: Density in the foam forming beaker: 28.0 kilograms per cubic meter. Hose test: 176.2 centimeters.

Example 11 (according to the present invention) A foam was produced as in Example 10, but with 6 pbm of isopropanol which were additionally added to the polyol component. The concentrations of the swelling agents based on the total mass of the foam-forming mixture were: water 0.84 percent by mass cyclopentane 4.24 percent by mass n-pentane 1.28 percent by mass isopropanol 2.65 percent by mass The obtained foam had the following properties: Density in the foam forming beaker: 26.7 kilograms per cubic meter. Hose test: 182.5 centimeters.

Example 12 (comparison) A foam was produced as in Example 6, but with 9.62 pbm of cyclopentane and 2.91 pbm of cyclohexane, instead of 12.53 pbm of n-pentane, which was added to the polyol component. The concentrations of the swelling agents based on the total mass of the foam-forming mixture were: water 0.87 mass percent cyclopentane 4.36 mass percent cyclohexane 1.32 mass percent The foam obtained had the following properties: Density in the foam forming beaker: 28.9 kilograms per cubic meter. Hose test: 166.6 centimeters.

Example 13 (in accordance with the present invention) A foam was produced as in Example 12, but with 6 pbm of isopropanol which were additionally added to the polyol component. The concentrations of the swelling agents based on the total mass of the foam-forming mixture were: water 0.84 mass percent cyclopenan 4.24 mass percent cyclohexane 1.28 mass percent isopronanol 2.65 mass percent The obtained foam had the following properties : Density in the foam forming beaker: 28.5 kilograms per cubic meter. Hose test: 177.1 centimeters.

Example 14 (comparison) A foam was produced as in Example 6, but with 5.88 pbm of cyclopentane and 5.88 pbm of isopentane, instead of 12.53 pbm of n-pentane which was added to the polyol component.

The concentrations of the swelling agents based on the total mass of the foam-forming mixture were: water 0.87 mass percent cyclopentane 2.66 mass percent isopentane 2.66 mass percent The foam obtained had the following properties: Density in the glass precipitate foam former: 28.2 kilograms per cubic meter. Hose test: 174.3 centimeters.

Example 15 (in accordance with the present invention) A foam was produced as in Example 14, but with 6 pbm of isopropanol which were additionally added to the polyol component. The concentrations of the swelling agents based on the total mass of the foam-forming mixture were: water 0.85 percent by mass cyclopentane 2.59 percent by mass isopentane 2.59 percent by mass isopropanol 2.65 percent by mass The obtained foam had the following properties : Density in the foam forming beaker: 26.7 kilograms per cubic meter. Hose test: 183.3 centimeters.

Example 16 (comparison) A foam was produced as in Example 6, but with 8.82 pbm of cyclopentane and 2.94 pbm of n-heptane, instead of 12.53 pbm of n-pentane that was added to the polyol component. The concentrations of the swelling agents based on the total mass of the foam-forming mixture were: water 0.87 mass percent cyclopentane 3.98 mass percent n-heptane 1.33 mass percent The foam obtained had the following properties: Density in the foam-forming beaker: 29.8 kilograms per cubic meter. Hose test: 155.3 centimeters.

Example 17 (in accordance with the present invention) A foam was produced as in Example 16, but with 6 pbm of isopropanol which were added further to the polyol component. The concentrations of the swelling agents based on the total mass of the foam-forming mixture were: water 0.85 percent by mass cyclopentane 3.88 percent by mass n-heptane 1.29 percent by mass isopropanol 2.64 percent by mass The foam obtained had the following properties Density in the foam forming beaker: 28.3 kilograms per cubic meter. Hose test: 161.7 centimeters.

Example 18 (comparison) The polyol component consisted of: 51.9 pbm of a polyol based on sorbitol and propylene oxide, OH number of 490 milligrams of KOH per gram, 18.5 pbm of an amine-based polyol and propylene oxide / ethylene oxide, OH number of 400 milligrams of KOH per gram, 25.8 pbm of potato starch, 1.27 pbm of a silicone stabilizer, as described in Example 1, 1.12 pbm of dimethylcyclohexylamine, and 1.41 pbm of water. 8.75 pbm of cyclopentane was added to 100 pbm of this polyol component. this mixture was subsequently intensively stirred with 158.5 pbm of the MDI crude product, NCO content of 31.5 mass percent. The concentrations of the swelling agents based on the total mass of the foam-forming mixture were: water 0.51 mass percent cyclopentane 3.11 mass percent The foam obtained obtained had the following properties: Density in the foam forming beaker: 48.8 kilograms per cubic meter. Start time / gel time / expansion time in s: 38/150/267 Hose test: 81.5 centimeters Example 19 (in accordance with the present invention) A foam was produced as in Example 18, but with 6 pbm of isopropanol which were additionally added to the polyol component. The concentrations of the swelling agents based on the total mass of the foam-forming mixture were: water 0.49 mass percent cyclopentane 3.04 mass percent isopropanol 2.27 mass percent The foam obtained had the following properties: Density in the foam-forming beaker: 45.3 kilograms per cubic meter. Start time / gel time / expansion time in s: 42/142/241. Hose test: 91.9 centimeters.

Despite a shorter gelling time and smaller amounts of water / cyclopentane, the foam flows better than that in Comparison Example 18.

Example 20 (comparison) The polyol component consisting of 5.41 pbm of an adduct of propylene glycol and propylene oxide, of OH number of 250 milligrams of KOH per gram, 54.05 pbm of a mixture of nitrogen containing polyols (ethylene oxide-oxide additives) propylene with nitrogen compounds), of OH number of 440 milligrams of KOH per gram, 24.32 pbm of a polyol based on sucrose and propylene oxide, OH number of 500 milligrams of KOH per gram, 1.62 pbm of dimethylcyclohexylamine, 2.77 pbm of a silicone stabilizer as described in Example 1 , 1.98 pbm of water and 9.92 pbm of cyclopentane, was intensively mixed with 132.4 pbm of crude MDI, an NCO content of 31.5 mass percent using an agitator (index: 112). The concentrations of the swelling agents based on the total mass of the foam-forming mixture were: water 0.85 percent by mass cyclopentane 4.30 percent by mass The obtained foam had the following properties: Density in the foam forming beaker: 32.0 kilograms per cubic meter. Hose test: 141.8 centimeters.

Start time / gel time / expansion time in s: 10/55/85.

The physical properties of foam after foaming in a steel mold heated to 45 ° C and having dimensions of 400 millimeters x 300 millimeters x 80 millimeters (degree of overfill: 1.11): Kernel density in kilograms per meter cubic: 32.2 Compression strength in the foam-forming direction in N / square millimeters: 0.12 Compression elastic modulus in the foam-forming direction in N / square millimeters: 3.55 Thermal conductivity (Hesto) in mW / mK: 21.1 (immediate value) Dimensional stability at -30 ° C, 24 hours in percentage: 0.1 / -0.1 / 0.0 Dimensional stability at + 80 ° C, 24 hours in percentage: 0.0 / 0.2 / 0.2 Example 21 (in accordance with the present invention) Polyurethane 4.24 pbm of methanol was added to the polyol component, as described in Example 20. The amount of the isocyanate was changed in such a way that the OH amount of the methanol was included in the index of 112, which remained constant. In order to have the same percentage amounts of water and cyclopentane in the foam-forming mixture, the composition was changed as follows: 5.09 pbm of propylene glycol adduct and propylene oxide, OH number of 250 milligrams of KOH per gram , 50.87 pbm of a mixture of nitrogen containing polyols (adducts of ethylene oxide and propylene oxide with nitrogen compounds), OH number of 440 milligrams of KOH per gram, 22.89 pbm of polyol based on sucrose and propylene oxide , OH number of 500 milligrams of KOH per gram, 1.52 pbm of dimethylcyclohexylamine, 2.54 pbm of a silicone stabilizer, as described in Example 1, 2.08 pbm of water, 10.77 pbm of cyclopentane, 4.24 pbm of methanol. The polyol component was intensively mixed with 147.8 pbm of crude MDI, an NCO content of 31.5 mass percent, using an agitator (index: 112, methanol included). The concentrations of the swelling agents based on the total mass of the foam-forming mixture were: water 0.84 percent by mass cyclopentane 4.30 percent by mass methanol 1.71 percent by mass The obtained foam had the following properties: Density in the foam forming beaker: 29.2 kilograms per cubic meter. Hose test: 157.7 centimeters. Initiation time / gelation time / expansion time in s: 11/46/72 The physical properties of foam after foaming in a steel mold heated to 45 ° C and having dimensions of 400 millimeters x 300 millimeters x 80 millimeters (degree of overfilling: 1.3): Kernel density in kilograms per meter cubic: 33.8 Compression strength in the direction of foam formation in N / square millimeters: 0.18 (calculated for 32.2 kilograms per cubic meter: 0.17) Elastic compression module in the foam-forming direction in N / square millimeters: 5.20 (calculated from 32.2 kilograms per cubic meter: 4.81) Thermal conductivity (Hesto) in mW / mK: 21.2 (immediate value) Dimensional stability at -30 ° C, 24 hours in percentage: 0.1 / 0.0 / 0.0 Dimensional stability a + 80 ° C, 24 hours as a percentage: 0.1 / 0.3 / 0.1 The increases in compressive strength and elastic modulus were significantly greater than those corresponding to the density increase of 32.2 to 33.8 kilograms per cubic meter. The foam-forming mixture flowed better than the mixture in Comparative Example 20. The density in the beaker was lower. Despite the lower gelation and expansion times, the flow performance was improved and the density of the beaker was decreased. The compressive strength and elastic compression modulus for a density of 32.2 kilograms per cubic meter were calculated from the density values for 33.8 kilograms per cubic meter using the following relationship that is known to those skilled in the art: (32.2 /33.8) • 6 x measured value at 33.8 kilograms per cubic meter = calculated value for density of 32.2 kilograms per cubic meter. (The corresponding equation is provided, for example, in Polyurethanes World Congress 1993, pages 234-240, SB Burns and EL Schmidt "The PIR / PUR Ratio: A Novel Trimer Conversion Test with High Correlation to the Factory Mutual Calorimeter for HCFC -141b Blown Polyisocyanurate Foams. "This relationship can be used to check whether the mechanical property changes simply attributable to the change in density or changes in the properties of the rigid foam shell substance, in our case, the strength of the shell substance it is improved, since, for example, the value of compressive strength of 0.17 N / square millimeter which is calculated for 32.2 kilograms per cubic meter in the variant of the present invention is significantly higher than the measured value of 0.12 N / square millimeter at 32.2 kilograms per cubic meter in ~ the comparison variant (Example 20).

Example 22 (in accordance with the present invention) The procedure was as in Example 21, but with 8.08 pbm of ethanol being added instead of 4.24 pbm of methanol. The concentrations of cyclopentane and water again remained constant as well as the index (112, ethanol included). The concentrations of the swelling agents based on the total mass of the foam-forming mixture were: water 0.84 percent by mass cyclopentane 4.3 percent by mass ethanol 3.23 percent by mass The foam obtained had the following properties: Density in the glass precipitate foam former: 28.5 kilograms per cubic meter. Hose test: 176.3 centimeters. Start time / gel time / expansion time in s: 12/53/82 The physical properties of the foam after foaming in the steel mold heated to 45 ° C and having dimensions of 400 millimeters x 300 millimeters x 80 millimeters (degree of overfilling of 1. 3): Kernel density in kilograms per cubic meter: 32.9 Compression strength in the foam-forming direction in N / square millimeters: 0.018 (calculated for 32.2 kilograms per cubic meter: 0.17) Elastic compression module in the direction of foam formation in N / square millimeter: 5.09 (calculated for 32.2 kilograms per cubic meter: 4.92) Thermal conductivity (Hesto) in mW / mK: 21.4 (immediate value) Dimensional stability at -30 ° C, 24 hours in percentage: 0.0 / 0.0 / 0.0 Dimensional stability at + 80 ° C, 24 hours in percentage: -0.1 / 0.2 / 0.1 The compressive strength and elastic compression modulus were significantly increased compared to Comparison Example 20. Despite the lower gelation and expansion times, the foam mixture flowed better than in the Comparison Example.

Example 23 (in accordance with the present invention) The procedure was as in Example 20, but with 4.8 pbm of isopropanol which was added further. The index (112, including isopropanol) again remained constant: The concentrations of the swelling agents based on the total mass of the foam-forming mixture were: water 0.85 percent by mass cyclopentane 4.30 percent by mass isopropanol 1.98 percent by massThe obtained foam had the following properties: Density in the foam forming beaker: 30.2 kilograms per cubic meter. Hose test: 161.8 centimeters. Start time / gel time / expansion time in s: 11/52/84.

Since due to the addition of isopropanol, the gelation and expansion times were somewhat longer than in Example 20, a correction was made using an additional 0.4 pbm of the catalyst mixture. If the penetration force in the fresh foam was measured using a standard pin having a diameter of 20 millimeters during the period of time immediately after the expansion time, beginning at 3 minutes as a measure of the subsequent hardening, the following were obtained values6 compared to the foam of Comparison Example 20: Time (minutes) Foam, Example 23, Penetration force in N: 40.1 66.0 81.5 91.0 96.0 Foam, Example 20, Penetration force in N: 41.0 69.0 90.0 97.0 104.5 Even when the gel time was comparable, the foam mixture according to the present invention flowed better, provided a lower density and the course of subsequent hardening was not adversely affected compared to the foam of Example 20, taking into account the lowest density The influence of the density was calculated using a method similar to the description of the density dependence of the mechanical data in Example 21, ie, the values of the penetration force of Example 23 were corrected by the factor. (volumetric density of the beaker of Example 20 / volumetric density of the beaker of Example 23) 1-6 = (32.2 / 30.2) 1 • 6 = 1.108: Time (minutes) Example 23, penetration force in N, corrected to 32 kilograms per cubic meter 44.4 73.1 90.32 100.8 106.4 This correction shows that the course of the subsequent hardening of the substance of the cell framework is not adversely affected, but rather, it is improved a little.

Claims (14)

R E I V I N D I C A C I O N E S:

1. A process for producing rigid foams based on isocyanate, by reacting a) organic polyisocyanates and / or organic polyisocyanates modified with b) at least one relatively high molecular weight compound containing at least two reactive hydrogen atoms and, if is desired, c) low molecular weight chain extension agents and / or crosslinking agents. 2. In the presence of d) swelling agents, e) catalysts and, if desired, f) auxiliary and / or additional additives, wherein the swelling agent used is a mixture of at least one hydrocarbon of low boiling temperature which it has from 3 to 7 carbon atoms and low molecular weight monohydric alcohols containing primary or secondary hydroxyl groups and having from 1 to 4 carbon atoms.

2. A process according to claim 1, wherein the swelling agent mixture is used in combination with the carbon dioxide formed from the water and the isocyanate.

3. A process according to claim 1 or 2, wherein the low boiling point hydrocarbons having from 3 to 7 carbon atoms are used in an amount of 0.1 percent to 12 percent by mass, based on the total amount of the foam.

4. A process according to any of claims 1 to 3, wherein the low molecular weight monohydric alcohols containing primary and secondary hydroxyl groups and having 1 to 4 carbon atoms are used in an amount of 0.1 to 6 percent by mass, based on the total amount of the foam.

5. A process according to any of claims 1 to 4, wherein the cyclopentane is used as the low boiling point hydrocarbon having from 3 to 7 carbon atoms.

6. A process according to any of claims 1 to 4, wherein the n-pentane is used as the low boiling point hydrocarbon having from 3 to 7 carbon atoms.

7. A process according to any one of claims 1 to 4, wherein the isopentane is used as the low boiling point hydrocarbon having from 3 to 6 to 7 carbon atoms.

8. A process according to any of claims 1 to 7, wherein the methanol is used as the low molecular weight monohydric alcohol containing primary or secondary hydroxyl groups and having 1 to 4 carbon atoms.

9. A process according to any of claims 1 to 7, wherein ethanol is used as the low molecular weight monohydric alcohol containing primary or secondary hydroxyl groups and having 1 to 4 carbon atoms.

10. A process according to any of claims 1 to 7, wherein n-propanol is used as the low molecular weight monohydric alcohol containing primary or secondary hydroxyl groups and having 1 to 4 carbon atoms.

11. A process according to any of claims 1 to 7, wherein the isopropanol is used as the low molecular weight monohydric alcohol containing primary or secondary hydroxyl groups and having 1 to 4 carbon atoms.

12. A process according to any of claims 1 to 7, wherein the appropriate isomers of butanol are used as the low molecular weight monohydric alcohols containing primary or secondary hydroxyl groups and having from 1 to 4 carbon atoms .

13. A mixture of the swelling agent for producing rigid isocyanate-based foams according to claim 1, comprising a mixture of at least one low boiling point hydrocarbon having from 3 to 7 carbon atoms and monohydric alcohols. of low molecular weight containing primary or secondary hydroxyl groups and having from 1 to 4 carbon atoms.

14. The use of the rigid isocyanate-based foams produced in accordance with claim 1, as an insulating material.