DE19962273A1 - Use of comminuted melamine-formaldehyde condensate foam or fiber material to produce flame-retardant hard polyurethane foams - Google Patents

Abstract

Comminuted melamine-formaldehyde condensate foam or fiber material (I) is used to produce flame-retardant hard polyurethane foams. Independent claims are also included for the following: (1) a process for producing flame-retardant hard polyurethane foams by reacting polyisocyanates with at least one compound containing at least two reactive hydrogen atoms in the presence of water or other blowing agents and other additives, in which (I) is added to the reaction mixture together with at least one flame retardant; (2) a hard polyurethane foam produced by a process as in (1).

Description

The invention relates to a method for producing flame retardant polyurethane foams.

The production of polyurethanes (PUR) by implementing organic polyisocyanates with compounds with at least two reactive hydrogen atoms, for example polyoxyalkylene polyamines and / or preferably organic polyhydroxyl compounds, especially polyetherols with molecular weights from Z. B. 300 to 6000, and optionally chain extension and / or crosslinking agents with molecular weights up to approx. 400 in the presence of catalysts, blowing agents, flame retardants and other auxiliaries and / or additives are known and has been described many times. A summary overview about the production of PUR z. B. in the plastics manual, Volume VII, Polyurethane, Carl-Hanser-Verlag, Munich, 1st edition 1966, published by Dr. R. Vieweg and Dr. A. Höchtlen, as well as 2nd edition 1983 and 3rd edition 1993, published by Dr. G. Oertel.

There are a number of solutions to PUR foams equip thermostable or their flammability reduce. During e.g. B. preferably in rigid foam applications organic phosphorus derivatives and ammonium polyphosphates use find, melamine is the preferred in soft foam applications Flame retardant, with the required flame retardant tests a number of applications with difficulty are.

The signs have also been tried in the past disadvantages of PUR foams due to partial use of melamine-formaldehyde condensates, which, however, are not foams or as fiber material to fix. So in DE-A-38 01 456 a melamine-formaldehyde condensate in combination with Pentaerythritol, ammonium polyphosphate and dicyanamide as a flame protective agent for PUR rigid foam claimed. In doing so, too due to the high density of this condensate, high proportions of Flame retardant used. The mixture contains at least 10% by weight of the melamine-formaldehyde condensate. In BE 857329 a copolymer of PUR and melamine-formaldehyde condensate wrote. Through appropriately used acidic catalysts (but these interfere with the PU formation process)  Shaped bodies containing formaldehyde condensate, which are correspondingly brittle are manufactured. In GB 1030162 Novolak derivatives or Melamine-formaldehyde condensates as a powdery material added to a polyol mixture. As another flame retardant serve ammonium polyphosphate and corn starch. The corresponding Materials have to be ground in an additional step. The synthesis-related one is particularly disturbing Water content resulting from the aminoplast condensation.

According to US-A-3897372 in addition to preferably used melamine also melamine-formaldehyde condensates, which in turn are obtained by grinding must be brought to a corresponding grain size set. In DT 25 37 859 is a flame retardant mixture described the u. a. by grinding a melamine formaldehyde Condensate is produced. High proportions are used for foaming CFCs required. JP 4068038 is used as a flame retardant additive Aminoplast powder with a grain size of 10 to 500 µm is used. Disturbing formaldehyde residues are excluded by the fact that the curing process of the aminoplast resin is controlled.

DE-A-196 43 818 describes composite elements made of foamed melamine Formaldehyde condensates and PUR foams are described. So that leaves at the side of the foamed melamine-formaldehyde condensates achieve good flame protection. The disadvantage is relative elaborate technology for the production of this composite element. For separate dosing, especially of fibers for ver stiffening purposes as a separate process stream exist a number of technological processes, such as B. the LFI process from Krauss-Maffei or the company's interwet process Canon.

For the continuous production of carpet back coatings with high filler content is the direct dosage of solid substances are also known (WO 9825983 and WO 9825984).

There are one for the shredding of foams and fibers Range of technological solutions, such as B. the long fiber Injection technology (LFI process) from Krauss-Maffei or a similar technology from Canon (Canon-wet). Both Companies carry out this shredding process immediately before Foam production in a related machine complex through. A number of meals are also common process for foams or corresponding cutting processes for fibers. The material that has been comminuted in this way can, processes described above or a PUR Component are added.

The object of the invention was to provide an improved halogen-free flame protection and higher thermal stability to realize in PUR foams without the processing properties of the system are impaired and without the PUR material is discolored.

Surprisingly, this task was solved by that in the production of the PUR foams the reaction mixture Melamine-formaldehyde condensates in the form of foams and / or Fibers in combination with at least one flame retardant be added.

The invention accordingly relates to a method for the manufacture provision of flame-retardant PUR foams through implementation of organic and / or modified organic polyiso cyanates (a) with at least one compound with at least two reactive hydrogen atoms (b) in the presence of water and / or other blowing agents (c) and other auxiliaries and additives (d), which is characterized in that the reaction mixture Melamine-formaldehyde condensates in the form of foams and / or Fibers in combination with at least one flame retardant be added.

The invention furthermore relates to the use of crushed melamine-formaldehyde condensate foam or fiber material for the production of flame-retardant PUR foams as well as the PUR foams produced by this process self.

In our investigations we surprisingly found that it is possible to use flame retardant and thermostable PUR foams generated by adding melamine-formaldehyde Condensates in the form of foams and / or fibers in combination be added with at least one flame retardant.

Rather, it would have been expected that the solids content adverse effects on the foam structure with a ver fire behavior would deteriorate.

All pre-foamed melamine form or aldehyde condensates present as fiber material are suitable for use in accordance with the invention. An open-cell foam with a density of 5 to 60 kg / m ³ is preferably used. Such foams are manufactured, for example, by BASF AG under the name Basotect®. These foams are described, for example, in EP-A-017672. Melamine form aldehyde condensates in fiber form are u. produced by BASF Aktiengesellschaft. Basofil®, marketed as staple fiber, is particularly suitable for the application case claimed here.

The melamine-formaldehyde condensates are crushed used, preferably in a particle size of less than 20 mm, particularly preferably less than 5 mm. One wishes for example in the case of PUR moldings, a reinforcing effect, larger particles, preferably longer fibers, be used.

The melamine-formaldehyde condensates are advantageously in Proportions of 1 to 20% by weight, preferably 1 to 10% by weight, each based on the total weight of the system.

The melamine-formaldehyde condensates are according to the invention in Combined with at least one flame retardant. Ins are suitable as flame retardants for this combination special melamine, ammonium polyphosphate and / or expanded graphite.

The ratio of the melamine-formaldehyde condensates to those with The flame retardant used is advantageously 1 to 2 up to 1 in 40.

The supply of the melamine-formaldehyde condensate and flame retardant The reaction mixture can be added in various ways respectively.

According to an advantageous embodiment, the melamine form aldehyde condensate as foam or fiber material over a Shredding device directly as a separate process stream in the PU processing machine to be metered component stream set. The problem of dosing shredded foam or fiber material could be solved by the fibers or the foam is continuously fed to a grinding or cutting tool leads and the material so comminuted advantageously is dosed directly.

The shredded foam or fiber material becomes more common via a metering device into the outlet channel of the PUR System components dosed.

It is also possible that the shredded foam or fiber submitted material and then through the liquid or on foaming PUR system is wetted. This technology could e.g. B. find application in a belt process. It will be advantageous liable to the submitted layer of melamine-formaldehyde  Condensate applied the liquid PUR mass. This pervades then the shredded material. This way you can at for example, an increased concentration of such melamine form aldehyde condensates in the outer area of the molded polyurethane body produce.

It is also possible to use the shredded foam or fiber premix the material in the A or B component.

The manufacture of the flame-retardant and temperature-stable PUR Foams are made in a manner known per se by reaction of organic and / or modified organic polyiso cyanates (a) with at least one compound with at least two reactive hydrogen atoms (b) in the presence of water and / or other blowing agents (c) and other auxiliaries and additives (d).

For the starting components that can be used for the method according to the invention, the following must be carried out:
Suitable organic and / or modified organic isocyanates for the production of the rigid PUR foams according to the invention are the aliphatic, cycloaliphatic araliphatic and preferably aromatic polyvalent isocyanates known per se.

The following may be mentioned as examples: alkylene diisocyanates with 4 to 12 carbon atoms in the alkylene radical, such as 1,12-dodecanedi isocyanate, 2-ethyl-tetramethylene-1,4-diisocyanate, 2-methylpenta methylene diisocyanate 1,5, tetramethylene diisocyanate 1,4 and before preferably 1,6-hexamethylene diisocyanate, cycloaliphatic diiso cyanates, such as cyclohexane-1,3- and -1,4-diisocyanate and any Mixtures of these isomers, 1-isocyanato-3,3,5-trimethyl-5-iso cyanatomethylcyclohexane (IPDI), 2,4- and 2,6-hexahydrotoluylene diisocyanate and the corresponding isomer mixtures, 4,4'-, 2,2'- and 2,4'-dicyclohexylmethane diisocyanate and the ent speaking isomer mixtures, and preferably aromatic di- and polyisocyanates, such as. B. 2,4- and 2,6-tolylene diisocyanate and the corresponding mixtures of isomers, 4,4'-, 2,4'- and 2,2'-di phenylmethane diisocyanate and the corresponding mixtures of isomers, Mixtures of 4,4'- and 2,2'-diphenylmethane diisocyanates, poly phenylpolymethylene polyisocyanates, mixtures of 4,4'-, 2,4'- and 2,2'-diphenylmethane diisocyanates and polyphenylpolymethylene poly isocyanates (raw MDI) and mixtures of raw MDI and toluene diisocyanates. The organic di- and polyisocyanates can used individually or in the form of their mixtures.  

So-called modified polyvalent iso are also common cyanate, d. H. Products made by chemical conversion of organic Di- and / or polyisocyanates are obtained used. Example ester, urea, biurethane, allophanate, Carbodiimide, isocyanurate, urethdione and / or urethane groups containing di- and / or polyisocyanates. Come in detail For example, consider: modified 4,4'-diphenylmethane di isocyanate, modified 4,4'- and 2,4'-diphenylmethane diisocyanate mixtures, modified raw MDI or 2,4- or 2,6-tolylene diisocyanate, urethane-containing organic, preferably aromatic polyisocyanates with NCO contents of 44 to 15% by weight, preferably from 31 to 21% by weight, based on the total weight, for example reaction products with low molecular weight diols, Triplets, dialkylene glycols, trialkylene glycols or polyoxy alkylene glycols with molecular weights up to 6000, in particular with molecular weights up to 1500, these as di- or poly oxyalkylene glycols can be used individually or as mixtures can. Examples include: diethylene and dipropylene glycol, polyoxyethylene, polyoxypropylene and polyoxypropylene polyoxyethylene glycols, triols and / or tetrols. Are suitable also prepolymers containing NCO groups with NCO contents of 25 up to 3.5% by weight, preferably from 21 to 14% by weight, based on the total weight made from those described below Polyester and / or preferably polyether polyols and 4,4'-di phenylmethane diisocyanate, mixtures of 2,4'- and 4,4'-diphenyl methane diisocyanate, 2,4- and / or 2,6-tolylene diisocyanates or Raw MDI. Liquid carbodiimide groups have also proven successful and / or polyisocyanates containing isocyanurate rings with NCO Contained from 33.6 to 15, preferably 31 to 21,% by weight, based on the total weight, e.g. B. based on 4,4'-, 2,4'- and / or 2,2'-diphenylmethane diisocyanate and / or 2,4- and / or 2,6-tolylene diisocyanate.

The modified polyisocyanates can be used together or with unmodified organic polyisocyanates, such as. B. 2,4'-, 4,4'-diphenylmethane diisocyanate, crude MDI, 2,4- and / or 2,6-tolylene diisocyanate can be mixed.

Organic polyisocyanates and are therefore preferably used: mixtures of toluene diisocyanates and raw MDI or mixtures of modified, Organic polyisocyanates containing urethane groups with a NCO content of 44 to 15 wt .-%, especially those based of tolylene diisocyanates, 4,4'-diphenylmethane diisocyanate, Di phenylmethane diisocyanate isomer mixtures or crude MDI and ins  special raw MDI with a diphenylmethane diisocyanate isomer content of 30 to 80 wt .-%, preferably from 30 to 55 wt .-%.

b) As higher molecular weight compounds with at least two reactive Hydrogen atoms are used to manufacture the invention PUR foams expediently those with a functional act of 2 to 4, preferably 2 to 3, and a molecular weight from 300 to 8000, preferably from 300 to 5000.

Have proven themselves. B. polyether polyamines and / or preferably Polyols selected from the group of polyether polyols, poly ester polyols, polythioether polyols, polyester amides, hydroxyl group-containing polyacetals and hydroxyl-containing ali phatic polycarbonates or mixtures of at least two of the mentioned polyols. Polyether polyols are preferably used and / or polyester polyols. The hydroxyl number of the polyhydroxyl Connections for flexible foams are usually 20 up to 80 and preferably 28 to 56, for rigid foams 300 to 800, preferably 400 to 600.

The polyether polyols used in component (b) are by known methods, for example by anionic poly merization with alkali hydroxides, such as. B. sodium or potassium hydroxide, or alkali alcoholates, such as. B. sodium methylate, Sodium or potassium ethylate or potassium isopropylate as catalyze sators and with the addition of at least one starter molecule, the 2 to 4, preferably 2 to 3, reactive hydrogen atoms bound contains, or by cationic polymerization with Lewis acids, such as antimony pentachloride, boron fluoride etherate and the like. a., or bleach earth, as catalysts from one or more alkylene oxides with 2 to 4 carbon atoms in the alkylene radical. For monofunctional starters can also be used for special purposes be integrated into the polyether structure.

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 1,2-propylene oxide. The alkylene oxides can be used individually, alternately one after the other or as mixtures be used.

Examples of suitable starter molecules are: water, organic dicarboxylic acids, such as succinic acid, adipic acid, Phthalic acid and terephthalic acid, aliphatic and aromatic, optionally N-mono-, N, N- and N, N'-dialkyl substituted Diamines with 1 to 4 carbon atoms in the alkyl radical, such as optionally mono- and dialkyl-substituted ethylenediamine, Diethylenetriamine, triethylenetetramine, 1,3-propylenediamine,  1,3- or 1,4-butylenediamine, 1,2-, 1,3-, 1,4-, 1,5- and 1,6-hexa methylenediamine, phenylenediamine, 2,3-, 2,4- and 2,6-toluenediamine and 4,4 ', 2,4'- and 2,2'-diaminodiphenylmethane. As a starter Molecules are also suitable: alkanolamines, such as. B. Ethanolamine, N-methyl- and N-ethylethanolamine, dialkanolamines, such as B. diethanolamine, N-methyl and N-ethyldiethanolamine, and Trialkanolamines, such as. B. triethanolamine, and ammonia. Preferential wise are used, especially two and / or trihydric alcohols, such as ethanediol, 1,2-propanediol and 2,3, Diethylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, Glycerin, trimethylolpropane, pentaerythritol. The polyether polyols for flexible foams, preferably polyoxypropylene and polyoxy propylene polyoxyethylene polyols, have a functionality of preferably 2 to 4 and in particular 2 to 3 and molecular weights from 300 to 8000, preferably 300 to 6000 and ins particularly 1000 to 5000, and suitable polyoxytetramethylene glycols have a molecular weight of up to about 3500. polyether alcohols for rigid foams usually have more functional starters, such as B. sorbitol, sucrose and toluenediamine. With that Polyols having a functionality from 4 to 8, preferably from 4 to 6, manufactured. The molecular weight of these polyetherols is 250 to 1000.

Polymer-modified poly are also suitable as polyether polyols ether polyols, preferably graft polyether polyols, in particular those based on styrene and / or acrylonitrile, which are In-situ polymerization of acrylonitrile, styrene or preferably Mixtures of styrene and acrylonitrile, e.g. B. in weight ratio 90: 10 to 10: 90, preferably 70: 30 to 30: 70, expediently in the aforementioned polyether polyols analogous to the details of German patents 11 11 394, 12 22 669 (US 3304273, 3383351, 3523093), 11 52 536 (GB 1040452) and 11 52 537 (GB 987618) are made, as well as polyether poly dispersions, which as disperse phase, usually in an amount of 1 to 50% by weight, preferably 2 to 25 wt .-%, contain: z. B. polyureas, Polyhydrazide, poly containing tert-amino groups urethanes and / or melamine and the z. B. be described in EP-B-011752 (US 4304708), US-A-4374209 and DE-A-32 31 497.

The polyether polyols can be used individually or in the form of mixtures be used.

Suitable polyester polyols can be prepared, for example, from organic dicarboxylic acids having 2 to 12 carbon atoms, preferably aliphatic dicarboxylic acids having 4 to 6 carbon atoms, polyhydric alcohols, preferably diols, having 2 to 12 carbon atoms, preferably 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 both individually and in a mixture with one another. Instead of the free dicarboxylic acids, the corresponding dicarboxylic acid derivatives, such as. B. dicarboxylic acid esters of alcohols having 1 to 4 carbon atoms or dicarboxylic acid anhydrides. Adipic acid and dicarboxylic acid mixtures of succinic, glutaric and adipic acid are preferably used in proportions of, for example, 20 to 35: 35 to 50: 20 to 32 parts by weight, in the case of polyester polyols for rigid foam applications in particular phthalic acid and terephthalic acid. Examples of dihydric and polyhydric alcohols are: ethanediol, diethylene glycol, 1,2- or 1,3-propane diol, dipropylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexane diol, 1.10 -Decanediol, glycerin and trimethylolpropane. Preference is given to using ethanediol, diethylene glycol, 1,4-butanediol, 1,5-pentanediol and 1,6-hexanediol. Polyester polyols from lactones, e.g. B. ε-caprolactone, or hydroxy carboxylic acids, e.g. B. ω-hydroxycaproic acid.

The organic polyols can be used to produce the polyester polyols Polycarboxylic acids and / or derivatives and polyhydric alcohols catalyst-free or preferably in the presence of esterification catalysts, suitably in an atmosphere of inert gas such as B. nitrogen, carbon monoxide, helium, argon and. a., in the melt at temperatures of 150 to 250 ° C, preferably 180 to 220 ° C, optionally under reduced pressure up to the desired acid number, which is advantageously less than 10, is preferably less than 2, can be polycondensed. To a preferred embodiment is the esterification mixture at the above temperatures up to an acid number of 80 to 30 mg KOH / g, preferably 40 to 30 mg KOH / g, below Normal pressure and then under a pressure of less than 500 mbar, preferably 50 to 150 mbar, polycondensed. As Esterification catalysts come, for example, iron, cadmium, Cobalt, lead, zinc, antimony, magnesium, titanium and tin catalysts in the form of metals, metal oxides or metal salt into consideration. However, the polycondensation can also be in liquid phase in the presence of dilution and / or drag means such. As benzene, toluene, xylene or chlorobenzene azeotropic distillation of the condensation water leads. To produce the polyester polyols organic polycarboxylic acids and / or derivatives and polyvalent Alcohols advantageously in a molar ratio of 1: 1 to 1.8, preferably from 1: 1.05 to 1.2, polycondensed.  

The polyester polyols obtained for flexible foams have preferably a functionality of 2 to 4, in particular 2 to 3, and a molecular weight of 480 to 3000, especially 600 to 2000. The polyester polyols obtained for rigid foams preferably a functionality of 2 to 3 and a molecular weight from 250 to 1000, in particular 400 to 800.

The polyether polyols can be just like the polyester polyols individually or in the form of mixtures. Can also them with the graft polyols or polyester polyols as well the hydroxyl-containing polyester amides, polyacetals, poly carbonates and / or polyether polyamines are mixed.

As polyacetals containing hydroxyl groups such. B. from Glycols, such as diethylene glycol, triethylene glycol, 4,4'-dihydro xyethoxydiphenyldimethylmethane, hexanediol and formaldehyde questionable connections. Also through polymerization Suitable polyacetals can be produced from cyclic acetals. Polycarbonates containing hydroxyl groups are those of known type into consideration, for example, by order setting of diols, such as 1,3-propanediol, 1,4-butanediol and / or 1,6-hexanediol, diethylene glycol, triethylene glycol or tetra ethylene glycol with diaryl carbonates, e.g. B. diphenyl carbonate, or Phosgene can be produced. The polyester amides include e.g. B. from polyvalent, saturated and / or unsaturated Carboxylic acids or their anhydrides and polyvalent saturated and / or unsaturated amino alcohols or mixtures of more valuable alcohols and amino alcohols and / or polyamines ge won, predominantly linear condensates. Suitable polyethers Polyamines can be made from the above-mentioned polyether polyols known methods can be produced. Named as an example be the cyanoalkylation of polyoxyalkylene polyols and closing hydrogenation of the nitrile formed (US-A-3267050) or the partial or complete amination of polyoxyalkylene polyols with amines or ammonia in the presence of hydrogen and catalysts (DE-A-12 15 373).

The polyurethane foams can be used with or without of chain extenders and / or crosslinking agents become. To modify the mechanical properties, e.g. B. the hardness, however, the addition of chain extension agents, crosslinking agents or optionally also mixtures of which prove to be advantageous. As chain extension and / or Crosslinking agents are used with diols and / or triols Molecular weights less than 400, preferably 60 to 300. In For example, aliphatic, cycloaliphatic and / or araliphatic diols with 2 to 14, preferably 4  to 10, carbon atoms, such as. B. ethylene glycol, propane diol-1,3, decanediol-1,10, o-, m-, 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, glycerin and trimethylol propane, and low molecular weight hydroxyl-containing polyalkylene oxides based on ethylene and / or 1,2-propylene oxide and before mentioned diols and / or triols as starter molecules.

If chains are used to manufacture the polyurethane foams extenders, crosslinking agents or mixtures thereof Find application, they are expediently in a quantity up to 20% by weight, preferably from 1 to 8% by weight on the weight of component (b).

As blowing agents (c) from polyurethane chemistry can all Commonly known chlorofluorocarbons (CFCs) and highly and / or perfluorinated hydrocarbons can be used. The However, the use of these substances becomes strong for ecological reasons restricted or completely discontinued. In addition to HCFC and HFC offer in particular aliphatic and / or cycloaliphatic Hydrocarbons, especially pentane and cyclopentane, or Acetals such as B. methylal, as an alternative blowing agent. This Physical blowing agents are usually the polyol component of the system added. However, you can also in the isocyanate component or as a combination of both the polyol component and the isocyanate component are added. It is also possible to use them together with high and / or perfluorinated hydrocarbons in the form of an emulsion of Polyol component. As emulsifiers, if they are used, are usually oligomeric acrylates used as Side groups bound polyoxyalkylene and fluoroalkane contain and a fluorine content of about 5 to 30 wt .-% exhibit. Such products are from plastic chemistry well known, e.g. B. from EP-A-351614.

The amount of blowing agent or blowing agents used mixture is 1 to 25 wt .-%, preferably 1 to 15% by weight, based in each case on the weight of component (b).

It is also possible and customary, particularly in soft foam, as blowing agent of the polyol component water in an amount of 0.5 to 15 wt .-%, preferably 1 to 5 wt .-%, based on the Add weight of component (b). The water additive can be in Combination with the use of the other blowing agents described respectively.  

The reaction mixture for the production of the PUR In addition to the melamine described above, foams are Formaldehyde condensates in the form of foams and / or fibers Combination with at least one flame retardant usually further auxiliaries and / or additives (d) are added. Examples include catalysts, if appropriate other flame retardants, surface-active substances, foam stabilizers, cell regulators, fillers, dyes; Pigments, Hydrolysis inhibitor, fungistatic and bacteriostatic acting substances.

In particular, compounds are used as catalysts which greatly accelerate the reaction of the reactive hydrogen atoms, in particular compounds of component (b) containing hydroxyl groups, with the organic, optionally modified polyisocyanates (a). Organic metal compounds, preferably organic tin compounds, such as tin (II) salts of organic carboxylic acids, for. B. tin (II) - acetate, tin (II) octoate, tin (II) ethylhexoate and tin (II) - laurate, and the dialkyltin (IV) salts of organic carboxylic acids, for. B. dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate and dioctyltin diacetate. The organic metal compounds are used alone or preferably in combination with strongly basic amines. Examples include amidines such as 2,3-dimethyl-3,4,5,6-tetrahydropyrimidine, tertiary amines such as triethylamine, tributylamine, dimethylbenzylamine, dimethylcyclohexylamine, N-methyl-, N-ethyl-, N-cyclohexylmorpholine, N , N, N ', N'-tetra-methylethylenediamine, N, N, N', N'-tetramethylbutane diamine, N, N, N ', N'-tetramethyl-hexanediamine-1,6, pentamethyl diethylenetriamine, tetramethyldiaminoethyl ether, bis - (dimethyl aminopropyl) urea, dimethylpiperazine, 1,2-dimethylimidazole, 1-azabicyclo (3,3,0) octane and preferably 1,4-diazabicyclo (2,2,2) octane, and Aminoalkanol compounds such as triethanolamine, triisopropanolamine, N-methyl and N-ethyldiethanolamine and dimethylethanolamine. Other suitable catalysts are:
Tris- (dialkylaminoalkyl) -s-hexahydrotriazines, in particular tris- (N, N-dimethylaminopropyl) -s-hexahydrotriazine, tetraalkyl ammonium hydroxides, such as tetramethylammonium hydroxide, alkali hydroxide, such as sodium hydroxide, and alkali metal alcoholates, such as sodium methylate and potassium isopropylate, as well as long chain fatty acids with 10 to 20 carbon atoms and optionally pendant OH groups. 0.01 to 5% by weight, in particular 0.05 to 2% by weight, of catalyst or catalyst combinations, based on the weight of components (b), are preferably used.

At least one flame retardant is described as above according to the invention in combination with the melamine-formaldehyde Condensates used. As a flame retardant for this Combination are particularly suitable for melamine and ammonium poly phosphate and / or expandable graphite.

Other flame retardants can also be found below described A or B components are metered. Suitable Flame retardants, optionally in addition to the invention in combination with the melamine-formaldehyde condensates set flame retardants are added, for example Tricresyl phosphate, tris (2-chloroethyl) phosphate, tris (2-chloro propyl) phosphate, tetrakis (2-chloroethyl) ethylene diphosphate, di methyl methanephosphonate, diethanolaminomethylphosphonic acid diethyl esters and commercially available halogen-containing flame retardant polyols. In addition to the halogen-substituted phosphates already mentioned can also use inorganic or organic flame retardants, such as red phosphorus, alumina hydrate, antimony trioxide, arsenic oxide and Calcium sulfate for flame retarding the polyisocyanate polyadditions products are used. In general, it has been useful moderately proven, 1 to 40 parts by weight, preferably 1 to 20 parts by weight Parts, the flame retardant mentioned for 100 parts by weight to use component (b).

As surface-active substances such. B. Connections in Consider which to support the homogenization of the Aus serve and are also suitable, if necessary, the Regulate cell structure of plastics. May be mentioned at for example emulsifiers, such as the sodium salts of castor oil sulfates, or of fatty acids and salts of fatty acids with Amines, e.g. B. oleic acid diethylamine, stearic acid diethanolamine, ricinoleic acid diethanolamine, salts of sulfonic acids, e.g. B. alkali or ammonium salts of dodecylbenzene or dinaphthylmethane di sulfonic acid and ricinoleic acid, foam stabilizers, such as siloxane oxalkylene copolymers and other organopolysiloxanes, ox ethylated alkylphenols, ethoxylated fatty alcohols, paraffin oils, Castor oil or ricinoleic esters, Turkish red oil and peanut oil, and cell regulators such as paraffins, fatty alcohols and dimethyl poly siloxanes. To improve the emulsifying effect, the cell structure and / or stabilization of the foam are also suitable the above described oligomeric acrylates with polyoxyalkylene and fluorine alkane residues as side groups. The surface-active substances are usually in amounts of 0.01 to 5 parts by weight, be applied to 100 parts by weight of the structural component (b) applied.  

As fillers, especially reinforcing fillers substances are the usual organic and known per se inorganic fillers, reinforcing agents, weighting agents, Agents for improving the abrasion behavior in paints, Understand coating agents, etc. In particular, be with Playfully called: inorganic fillers, such as silicate Minerals, for example layered silicates, such as antigorite, Serpentine, hornblende, ampibole, chrisotile and talc, metal oxides, such as kaolin, aluminum oxides, titanium oxides and iron oxides, Metal salts such as chalk, heavy spar and inorganic pigments, such as cadmium sulfide and zinc sulfide, and glass and. a. Preferably Kaolin (China Clay), aluminum silicate and Coprecipitates from barium sulfate and aluminum silicate as well as natural liche and synthetic fibrous minerals, such as wollastonite, Metal and in particular glass fibers of different lengths, the can optionally be arbitrated. As an organic filling substances are considered, for example: coal, rosin, Cyclopentadienyl resins and graft polymers as well as cellulose fibers, polyamide, polyacrylonitrile, polyurethane, polyester fibers based on aromatic and / or aliphatic Dicarboxylic acid esters and especially carbon fibers. The inorganic and organic fillers can be used individually or as Mixtures are used and are the reaction mixture before advantageously in amounts of 0.5 to 50% by weight 1 to 40% by weight, based on the weight of components (a) and (b), but with the content of mats, nonwovens and fabrics made from natural and synthetic fibers values up to Can reach 80 wt .-%.

Details of the other usual auxiliary and additives are in the specialist literature, for example the Monograph by J. H. Saunders and K. C. Frisch "High Polymers" Volume XVI, Polyurethanes, Parts 1 and 2, Verlag Interscience Publishers 1962 or 1964, or the plastic cited above manual, Polyurethane, Volume VII, Hanser-Verlag, Munich-Vienna, 1st to 3rd edition.

To produce the PUR foams according to the invention, the organic and / or modified organic polyisocyanates (a) and the compounds with at least two reactive hydrogen atoms (b) implemented in such amounts that the Equivalence ratio of NCO groups of the polyisocyanates (a) to Sum of the reactive hydrogen atoms of component (b) 0.80 to 1.25: 1, preferably 0.90 to 1.15: 1.  

PUR foams according to the inventive method advantageously by the one-shot method, for example with the help of high pressure or low pressure technology in open or closed molds, for example metallic Molds made. Continuous is also common Application of the reaction mixture to suitable belt lines for Generation of foam blocks.

After three, it has proven to be particularly advantageous component process and the crushed melamine Formaldehyde material consisting of a melamine formaldehyde Foam or a corresponding fiber material, in a mixture separately with the flame retardants to be used according to the invention dosed into the mixing head as the A component (b) to (d) and as component (B) the organic and / or modified organic isocyanates (a), optionally in Mixture with auxiliaries and / or additives, in particular also other flame retardants, component (d), to ver turn.

Components (A) and (8) are at a temperature of 15 to 90 ° C, preferably from 20 to 60 ° C and in particular from 20 to 40 ° C, mixed and in the open or optionally under introduced increased pressure in the closed mold or in a continuous work station on a belt that absorbs the reaction mass, applied. The mixing can mechanically using a stirrer, using a stirring screw or carried out by high pressure mixing in a nozzle become. The solids are advantageously separated reduced and fed to the mixing head as a third component or fed as raw material to the foaming station and there via a Cutting device crushed. The mold temperature be appropriately carries 20 to 110 ° C, preferably 30 to 60 ° C and especially 35 to 55 ° C.

According to a further process variant, the mixing takes place of the shredded material in whole or in part via the PUR Components.

The polyurethane foams produced by the process according to the invention have a density of 10 to 800 kg / m ³ , preferably 35 to 100 kg / m ³ and in particular 25 to 80 kg / m ³ . The systems of the invention show good processing properties. The foams have improved flame retardancy and higher thermal stability and show no discoloration of the PUR material.

The foams according to the invention are particularly suitable as Upholstery or sound-absorbing and temperature-stable material in the furniture and automotive sector, especially for manufacturing of vehicle seats and for encapsulating temperature sensitive units, but also as flame-retardant Rigid foam in the insulation area.

The present invention is based on the following Examples are explained in more detail.

Examples 1, 2, 4 and 6 according to the invention Examples 3 and 5 comparative experiments

100 parts by weight (GT) of an A component, consisting of

were converted to a polyurethane foam with a mixture of 80 GT Lupranat® T80 and 20 GT Lupranat® M20A. In example 6, the polyol component was reacted with Lupranat® M50.

Lupranol® 2040 - OH number 28 mg KOH / g, polyether based on ethylene oxide and propylene oxide (BASF);
Lupranol® 2042 - OH number 26 mg KOH / g, polyether based on ethylene oxide and propylene oxide (BASF);
Lupranol® 2047 - OH number 42 mg KOH / g, polyetherol based on ethylene oxide and propylene oxide (BASF);
Polyol 1 - polyether alcohol based on sucrose / glycerol propylene oxide; OH number 385 to 415 mg KOH / g;
Polyol 2 - polyether alcohol based on sucrose / pentaerythritol / diethylene glycol propylene oxide; OH number 375 to 430 mg KOH / g;
Polyol 3 - polyether alcohol based on ethylenediamine propylene oxide, OH number 720 to 780 mg KOH / g;
Basotect® - melamine-formaldehyde foam; Density: 10 kg / m ³ (BASF);
Lupragen® N 201, N 211, N 209 - amine catalysts (BASF);
ZM 99, KX 315 - catalysts (BASF);
Melamine, grain size 10 to 50 µm (90%) (BASF);
APP 423 - ammonium polyphosphate (from Hoechst);
Aeorosil 300 - silicon dioxide (from Degussa);
Fyrol 6 - flame retardant (from Solvay);
DPK - flame retardant (Bayer);
Lupranat® T80 - tolylene diisocyanate (80/20);
Lupranat® M20A, M50 - polyphenyl polyisocyanate;
Paper pillow test according to DIN 54 341;
Oxygen index - Brit. Standard D 2863-87;
Fire test according to B2 - DIN 4102.

In the fire behavior (paper pillow test) could in the examined Foam samples a significant improvement over the comparison test be determined. Fire class B2 for rigid foam can be achieved.

Claims (11)

1. Process for the preparation of flame-retardant polyurethane foams by reacting organic and / or modified organic polyisocyanates (a) with at least one compound having at least two reactive hydrogen atoms (b) in the presence of water and / or other blowing agents (c) and others Auxiliaries and additives (d), characterized in that melamine-formaldehyde condensates in the form of foams and / or fibers in combination with at least one flame retardant are added to the reaction mixture. 2. The method according to claim 1, characterized in that the Melamine-formaldehyde condensates in crushed form be used, the particle size less than 20 mm is. 3. The method according to claim 1 or 2, characterized in that the melamine-formaldehyde condensates in proportions of 1 to 20 wt .-%, based on the total weight of the system be set. 4. The method according to any one of claims 1 to 3, characterized characterized in that the ratio of melamine-formaldehyde Condensates to the flame retardants 1 to 2 used is up to 1 in 40. 5. The method according to any one of claims 1 to 4, characterized records that as a flame retardant melamine and / or expanded graphite can be used. 6. The method according to any one of claims 1 to 5, characterized records that the melamine-formaldehyde condensates as a foam fabric or fiber material via a comminution device directly as a separate process stream in the polyurethane Ver machine to be metered component stream added become. 7. The method according to any one of claims 1 to 6, characterized records that the crushed foam or fiber material via a dosing device in the outlet channel of the poly urethane system components is dosed.   8. The method according to any one of claims 1 to 5, characterized records that the crushed foam or fiber material submitted and by the liquid or foaming poly urethane system is wetted. 9. The method according to any one of claims 1 to 5, characterized records that the crushed foam or fiber material is premixed in the A or B component. 10. Use of crushed melamine-formaldehyde condensate Foam or fiber material for the production of flame protected polyurethane foams. 11. Flame retardant polyurethane foams, producible by Implementation of organic and / or modified organic Polyisocyanates (a) with at least one compound with at least two reactive hydrogen atoms (b) in the presence of water and / or other blowing agents (c) and others Auxiliaries and additives (d), the reaction mixture Melamine-formaldehyde condensates in the form of foams and / or Fibers in combination with at least one flame retardant be added.