CA2213161A1

CA2213161A1 - Storage-stable, flame retardant-containing polyol component

Info

Publication number: CA2213161A1
Application number: CA002213161A
Authority: CA
Inventors: Michael Reichelt; Rainer Hemsiek
Original assignee: Individual
Current assignee: BASF SE
Priority date: 1996-08-29
Filing date: 1997-08-28
Publication date: 1998-02-28
Also published as: EP0826707A1; JPH10152543A; DE19634886A1; CN1074009C; KR19980019094A; MX9706549A; CN1179440A

Abstract

In storage-stable, flame retardant-containing polyol components comprising at least one polyol plus, if desired, further relatively high molecular weight compounds containing at least two reactive hydrogen atoms and, if desired, low molecular weight chain extenders and/or crosslinkers and also blowing agents, catalysts, stabilizers and, if desired, further auxiliaries and/or additives, stabilizers used are imidazoles of the general formula (see fig. I), where R1 = C1-C4-alkyl, C1-C4-hydroxyalkyl or dimethylamino-C1-C4-alkyl and R2, R3, R4 = H or C1-C4-alkyl, and/or formic acid.
Rigid PUR foams based on isocyanate can be prepared by reacting this polyol component with organic and/or modified organic polyisocyanates and can be used as insulation material in the building sector.

Description

BASF Aktiengesellschaft 950948 O.Z. QOSO/47248 Storage-stable, flame retardant-containing polyol component 5 The present invention relates to storage-stable, flame retardant-cont~i~;ng polyol components which are used for the production of flame-resistant, rigid polyurethane (PUR) foams based on isocyanate. These rigid PUR foams are preferably used in the building sector as insulation materials.

Such rigid PUR foams based on isocyanate comprise as characteristic structural elements urethane and/or isocyanurate and/or biuret and/or allophanate and/or uretdione and/or urea and/or carbodiimide groups. In practice, it has been found to be 15 advantageous to prepare polyol components. These are liquid mixtures comprising the formulation constituents necessary for producing rigid PUR foams based on isocyanate, for example polyols, flame retardants and water plus, if desired, further auxiliaries and additives such as catalysts, retarders, physical 20 blowing agents, foam stabilizers, plasticizers, emulsifiers, dyes, fillers and anti-settling agents.

A summary overview of the production of rigid PUR foams and the starting materials used is given in, for example, 25 Kunststoff-Handbuch, Volume VII, ~Polyurethane", 1st Edition 1966, edited by Dr. R. Vieweg and Dr. A. Hochtlen and 2nd Edition, 1983, and also 3rd Edition, 1993, edited by Dr. G.
Oertel (Carl Hanser Verlag, Munich).

With the replacement of CFCs by alternative blowing agents, the C~2 generated by the isocyanate-water reaction is increasingly used as sole blowing agent or co-blowing agent together with hydrogen-containing CFCs, hydrogen-containing fluorocarbons or hydrocarbons. This is associated with a relatively high water 35 content in the polyol component. This leads, particularly in the simultaneous presence of flame retardants, to problems during the storage time prior to processing to give the rigid foam. As a result of hydrolytic processes, the acid content of the polyol component rises steadily. This results in increasingly long 40 reaction times in processing with the associated isocyanate component, which gives a poorer processibility and ; -;rs the properties of the resulting rigid PUR foam. The polyol components may have to be adjusted by further addition of catalyst or, in the most unfavorable case, have to be discarded. This has adverse 45 economic effects and the desired, prolonged storage times of weeks or months are virtually impossible to achieve in practice.
The search for storage-stable polyol components is therefore an BASF Aktiengesellschaft 950948 O.Z. 0050/47248 important industrial objective.

The documents BE 843 172, DE-A-3 607 964, EP-A-401 787, EP-A-410 467, EP-A-451 B26, JP 12 56 511, JP 20 47 125, JP 30 33 120, 5 JP 31 31 618, JP 40 55 419, JP 41 61 4 17, JP 42 02 215, JP 42 14 712, JP 52 09 034, JP 58 213 016, JP 60 084 319, JP 61 031 413, JP 61 031 414, JP 42 998 519, JP 50 70 544, US-A-4 165 412, US-A-431 753, US-A-4 481 309, US-A-5 240 964, WO 93 15 121 and WO
93 16 122 describe N-substituted imidazoles as catalysts for lO producing PUR foams-JP 30 64 312 and EP-A-560 154 describe the use of formic acid as blowing agent. According to JP 50 31 989, use is made of a 5 blowing agent combination comprising Freon 22 and formic acid which gives stable pH values and gelling times during storage.
The patents EP 322 801 and JP 11 04 611 describe modification of the amihe catalyst by molar amounts, based on the catalyst, of formic acid.
It is an object of the present invention to find suitable formulations for flame retardant-containing polyol components which have a satisfactory storage stability and lead to rigid PUR
foams having good mechanical and thermal properties.
We have found that this object is achieved by the use of imidazoles and/or formic acid as stabilizers.

The present invention accordingly provides storage-stable, flame 30 retardant-containing polyol components comprising at least one polyol plus, if desired, further relatively high molecular weight compounds containing at least two reactive hydrogen atoms and, if desired, low molecular weight chain extenders and/or crosslinkers and also blowing agents, catalysts, stabilizers and, if desired, 35 further auxiliaries and/or additives, wherein stabilizers used are imidazoles of the general formula R4 1 _ I R3 R1--N , N

where Rl = C1-C4-alkyl, C1-C4-hydroxyalkyl or dimethylamino-C1-C4-alkyl and R2, R3, R4 = H or C1-C4-alkyl, and/or formic acid.
The present invention further provides rigid PUR foams based on isocyanate and able to be produced by reacting this polyol BASF Aktiengesellschaft 950948 O.Z. 0050/47248 component with organic and/or modified organic polyisocyanates, and provides for their use as insulation material in the building sector.

5 The polyol components of the present invention also have good storage stabilities when they contain comparatively large amounts of flame retardants, water and catalysts. Further advantages are that the flame retardant action is not adversely affected by the stabilizers and that the stabilizers can be used in small 10 amounts Imidazoles which are preferably used are l-ethylimidazole, l-propylimidazole, l-butylimidazole, 1,3-dimethylimidazole, 15 1,5-dimethylimidazole, 1-ethyl-2-methylimidazole, l-methyl-2-ethylimidazole, 1-methyl-2-propylimidazole, l-n-butyl-2-methylimidazole, 1-isobutyl-2-methylimidazole, 1-(3-dimethylaminopropyl)imidazole, l,l'-(oxodiethylene)bis(imidazole), 20 1,1'-(oxodiethylene)bis(2-methylimidazole), very particularly preferably l-methylimidazole and 1,2-dimethylimidazole.

The imidazoles can be used individually or in admixture with one another.

Formic acid is likewise suitable as a stabilizer according to the invention. Formic acid can be employed either alone or in admixture with the above-described imidazoles.

30 A particularly advantageous embodiment makes use of combinations of formic acid with l-methylimidazole or 1,2-dimethylimidazole, and these combinations are therefore preferably employed.

35 Formic acid as stabilizer is usually used in an amount of from 0.01 to 0.5% by weight, preferably from 0.05 to 0.2% by weight, based on the polyol component.

Imidazoles as stabilizers are usually used in an amount of from 40 0.1 to 8% by weight, preferably from 0.5 to 4% by weight, based on the polyol component.

If both imidazoles and formic acid are used as stabilizers, the total amount used is from 0.1 to 8.5% by weight, based on the 45 polyol component.

BASF Aktiengesellschaft 950948 O.Z. 0050/47248 It was surprising and in no way foreseeable that both the formic acid known hitherto as blowing agent or as catalyst modifier and the substituted imidazoles known as polyurethane catalysts have a stabilizing action in flame retardant-containing polyol 5 components and thus make it possible for the first time to master the previously completely unsatisfactory storage stability problem of the polyol components. It was particularly surprising and not foreseeable that among the many types of tertiary amines only the substituted imidazoles have this stabilizing action;
10 this is all the more surprising since tertiary amines generally tend to increase the storage stability problem. As regards the stabilizing action of formic acid, it is to be emphasized that this occurs even at contents which are so low that virtually no blowing action is yet observed.

An economical process for preparing storage-stable, flame retardant-contA i ni ng polyol components which can be readily processed to form rigid PUR foams which are very suitable as insulation material in the building sector has thus been 20 developed.

The storage-stable, flame retardant-containing polyol components comprise at least one polyol plus, if desired, further relatively 25 high molecular weight compounds containing at least two reactive hydrogen atoms and, if desired, low molecular weight chain extenders and/or crosslinkers and also blowing agents, catalysts, stabilizers and, if desired, further auxiliaries and/or additives.

The storage-stable, flame retardant-contA;ning polyol components of the present invention are prepared using, with the exception of the specific stabilizers, the formative components known per se about which the following details may be given:

As polyols and also as any further relatively high molecular weight compounds contA;ning at least two reactive hydrogen atoms to be employed, use is advantageously made of those having a functionality of from 2 to 8, preferably from 2 to 6, and a 40 molecular weight of from 300 to 8000, preferably from 300 to 3000. Compounds which have been found to be useful are, for example, polyetherpolyamines and/or preferably polyols selected from the group consisting of polyether polyols, polyester polyols, polythioether polyols, polyesteramides, 45 hydroxyl-containing polyacetals and hydroxyl-contAining aliphatic polycarbonates or mixtures of at least two of the polyols mentioned. Preference is given to using polyester polyols and/or BASF Aktiengesellschaft 950948 O.Z. OO50/~7248 , polyether polyols. The hydroxyl number of the polyhydroxyl compounds is generally from 150 to 850 mg KOH/g and preferably from 200 to 600 mg KOH/g.

5 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 lO 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 here be used either individually or in admixture with 15 one another. In place 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 dicarboxylic acid mixtures of succinic, glutaric and adipic acid 20 in weight ratios of, 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-decanediol, 25 glycerol and trimethylolpropane. Preference is given to using ethanediol, diethylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol or mixtures of at least two of the diols mentioned, in particular mixtures of 1,4-butanediol, 1,5-pentanediol and 1,6-hexanediol. It is also possible to use 30 polyester polyols derived from lactones, eg. ~-caprolactone, or hydroxycarboxylic acids, eg. ~-hydroxycaproic acid.

To prepare the polyester polyols, the organic, eg. aromatic and 35 preferably aliphatic, polycarboxylic acids and/or derivatives and polyhydric alcohols can be polycondensed in the absence of catalysts or preferably in the presence of esterification catalysts, advantageously in an atmosphere of inert gas such as nitrogen, carbon monoxide, helium, argon, etc., in the melt at 40 from 150 to 250~C, preferably from 180 to 220~C, under atmospheric pressure or under reduced pressure 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 as the abovementioned temperatures to an acid 45 number of from 80 to 30, preferably from 40 to 30, under atmospheric pressure and subsequently under a pressure of less than 500 mbar, preferably from 50 to 150 mbar. Suitable esterification catalysts are, for example, iron, cadmium, cobalt, BASF Aktiengesellschaft 950948 O.Z. 0050/47248 lead, zinc, antimony, magnesium, titanium and tin catalysts in the form of metals, metal oxides or metal salts. However, the polycondensation can also be carried out in the liquid phase in the presence of diluents and/or entrainers such as benzene, 5 toluene, xylene or chlorobenzene for azeotropically distilling off the water of condensation.

To prepare the polyester polyols, the organic polycarboxylic acids and/or derivatives and polyhydric alcohols are 10 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 15 from 2 to 4, in particular from 2 to 3, and a molecular weight of from 480 to 3000, preferably from 600 to 2000 and in particular from 600 to 1500.

However, polyols which are particularly preferably used are 20 polyether polyols which are prepared by known methods, for example from one or more alkylene oxides having from 2 to 4 carbon atoms in the alkylene radical by anionic polymerization using alkali metal hydroxides such as sodium or potassium hydroxide or alkali metal alkoxides such as sodium methoxide, 25 sodium or potassium ethoxide or potassium isopropoxide as catalysts with addition of at least one initiator molecule containing from 2 to 8, preferably from 2 to 6, reactive hydrogen atoms in bonded form, or by cationic polymerization using Lewis acids such as antimony pentachloride, boron fluoride etherate, 30 etc. or bleaching earth as catalysts.

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 35 alkylene oxides can be used individually, alternately in succession or as mixtures. Examples of suitable initiator molecules are: water, organic dicarboxylic acid~ such as succinic acid, adipic acid, phthalic acid and terephthalic acid, aliphatic and aromatic, unalkylated or N-monoalkylated, N,N- or 40 N,N'-dialkylated diamines having from 1 to 4 carbon atoms in the alkyl radical, for example unalkylated, monoalkylated or dialkylated ethylenediamine, diethylenetriamine, triethylenetetramine, 1,3-propylene~i Ami ne, 1,3- or 1,4-butylenediamine, 1,2-, 1,3-, 1,4-, 1,5- and 45 1,6-hexamethylenediamine, phenylaminediamines, 2,3-, 2,4- and BASF Aktiengesellschaft 950948 O.Z. .0050/47248 2,6-tolylenediamine and 4,4~-, 2,4'- and 2,2'-diaminodiphenylmethane.

Other suitable initiator molecules are: alkanolamines such as 5 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 polyhydric, in particular dihydric and/or trihydric, alcohols 10 such as ethanediol, 1,2- and 1,3-propanediol, diethylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, glycerol, trimethylolpropane, pentaerythritol, sorbitol and sucrose.

15 The polyether polyols, preferably polyoxypropylene and polyoxypropylene-polyoxyethylene polyols, have a functionality of preferably from 2 to 8 and in particular from 2 to 6 and molecular weights of from 300 to 3000, preferably from 300 to 2000 and in particular from 400 to 2000, and suitable 20 polyoxytetramethylene glycols have a molecular weight up to about 3500.

Other suitable polyether polyols are polymer-modified polyether polyols, preferably graft polyether polyols, in particular those 25 based on styrene and/or acrylonitrile which are prepared by in situ polymerization of acrylonitrile, styrene or preferably mixtures of styrene and acrylonitrile, eg. in a weight ratio of from 90 : 10 to 10 : 90, preferably from 70 : 30 to 30 : 70, advantageously in the abovementioned polyether polyols using 30 methods similar to those given in the German Patents 11 11 394, 12 22 669 (US 3 304 273, 3 383 351, 3 523 093), 11 52 536 (GB 10 40 452) and 11 52 537 (GB 987 618), and also polyether polyol dispersions which comprise as dispersed phase, usually in an amount of from 1 to 50% by weight, preferably from 2 to 25% by 35 weight: eg. polyureas, polyhydrazides, polyurethanes cont~in;ng bonded tertiary amino groups andtor melamine, and are described, for example, in EP-B-011 752 (US 4 304 708), US-A-4 374 209 and DE-A-32 31 497.

40 Like the polyester polyols, the polyether polyols can be used individually or in the form of mixtures. Furthermore, they can be mixed with the graft polyether polyols or polyester polyols or with the hydroxyl-containing polyesteramides, polyacetals, polycarbonates andtor polyetherpolyamines.

CA 022l3l6l l997-08-28 BASF Aktiengesellschaft 950948 O.Z. 0050/47248 Suitable hydroxyl-containing polyacetals are, for example, the compounds which can be prepared from glycols such as diethylene glycol, triethylene glycol, 4,4'-dihydroxyethoxy(diphenyldimethylmethane), hexanediol and 5 formaldehyde. Suitable polyacetals can also be prepared by polymerization of cyclic acetals.

Suitable hydroxyl-contAining polycarbonates are those of the type known per se which can be prepared, for example, by reacting 10 diols such as 1,3-propanediol, 1,4-butanediol and/or 1,6-hexanediol, diethylene glycol, triethylene glycol or tetraethylene glycol with diaryl carbonates, eg. diphenyl carbonate, or phosgene.

The polyesteramides include, for example, the predo~in~tly linear condensates obtained from polybasic, saturated and/or unsaturated carboxylic acids or their anhydrides and polyfunctional saturated and/or unsaturated aminoalcohols or 20 mixtures of polyfunctional alcohols and aminoalcohols and/or polyamlnes.

Suitable polyetherpolyamines can be prepared from the abovementioned polyether polyols by known methods. Examples which 25 may be mentioned are the cyanoalkylation of polyoxyalkylene polyols and subsequent hydrogenation of the nitrile formed ~US 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).

The storage-stable, flame retardant-containing polyol components can, depending on the desired properties of the rigid PUR foams to be produced therefrom, be prepared without or with concomitant use of chain extenders and/or crosslinkers. The addition of chain 35 extenders, crosslinkers or, if desired, mixtures thereof can prove to be advantageous for modifying the mechanical properties, eg. the hardness. Chain extenders and/or crosslinkers used are diols and/or triols having molecular weights of less than 400, preferably from 60 to 300. Examples of suitable chain 40 extenders/crosslinkers are 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, o-, m-, p-dihydroxycylco~e~Ane~ diethylene glycol, dipropylene glycol and preferably 1,4-butanediol, 45 1,6-hexanediol and bis(2-hydroxyethyl)hydroquinone, triols such as 1,2,4-, 1~3~5-trihydroxycyclohe~ne~ glycerol and trimethylolpropane and low molecular weight hydroxyl-containing BASF Aktiengesellschaft 950948 O.Z. O050/47248 polyalkylene oxides based on ethylene and/or 1,2-propylene oxide and the abovementioned diols and/or triols as initiator molecules.

5 If chain extenders, crosslinkers or mixtures thereof are employed for preparing the rigid polyurethane foams, these are advantageously used in an amount of from 0 to 20% by weight, preferably from 2 to 8% by weight, based on the weight of the polyols used and any further relatively high molecular weight 10 compounds containing at least two reactive hydrogen atoms also used.

As already indicated above, as a result of the replacement of 15 CFCs by alternative blowing agents, water is increasingly used as sole or co-blowing agent, utilizing the blowing action of the CO2 generated by the isocyanate-water reaction. Furthermore, physical blowing agents can be additionally used.

20 Suitable physical blowing agents are liquids which are inert toward the organic, modified or unmodified polyisocyanates which are used in the further processing of the polyol components of the present invention to give rigid PUR foams and have boiling points below 100~C, preferably below 50~C, in particular from 25 -50~C to 30~C, at atmospheric pressure so that they vaporize under the action of the exothermic polyaddition reaction. Examples of such preferably used liquids are alkanes such as heptane, hexane, n- and iso-pentane, preferably industrial mixtures of n- and iso-pentanes, n- and iso-butane and propane, cycloalkanes such as 30 cyclopentane and/or cyclohexane, ethers such as furan, dimethyl ether and diethyl ether, ketones such as acetone and methyl ethyl ketone, alkyl carboxylates such as methyl formate, dimethyl oxalate and ethyl acetate and halogenated hydrocarbons such as methylene chloride, dichloromonofluoromethane, difluoromethane, 35 trifluoromethane, difluoroethane, tetrafluoroethane, chlorodifluoroethanes, 1,1-dichloro-2,2,2-trifluoroethane, 2,2-dichloro-2-fluoroethane and heptafluoropropane. Mixtures of these low-boiling liquids with one another and/or with other substituted or unsubstituted hydrocarbons can also be used. Also 40 suitable are organic carboxylic acids such as formic acid, acetic acid, oxalic acid, ricinoleic acid and carboxyl-containing compounds.

Preference is given to using water, chlorodifluoromethane, 45 chlorodifluoroethanes, dichlorofluoroethanes, pentane mixtures, cyclohexane and mixtures of at least two of the blowing agents, eg. mixtures of water and cyclohexane, mixtures of BASF Aktiengesellschaft 950948 O.Z. 0050/47248 chlorodifluoromethane and l-chloro-2,2-difluoroethane and, if desired, water.

If water serves as blowing agent, it is preferably added in an 5 amount of from 0.5 to 5% by weigh~. ~he water addition can be carried out in combination with the addition of the other blowing agents described.

lO The total amount of blowing agent or blowing agent mixture used is from 1 to 25% by weight, preferably from 5 to 15~ by weight.

The amounts indicated are in each case based on the weight of the total polyol component.

Catalysts used are the compounds customary for the production of rigid PUR foams which strongly accelerate the reaction of the compounds of the polyol component containing reactive hydrogen atoms, in particular hydroxyl groups, with the organic, modified 20 or unmodified polyisocyanates.

Use is advantageously made of basic PUR catalysts, for example tertiary amines such as triethylamine, tributylamine, dimethylbenzylamine, dicyclohexylmethylamine, 25 dimethylcyclohexylamine, bis~N,N-dimethylaminoethyl) ether, bis(dimethylaminopropyl)urea, N-methylmorpholine or N-ethylmorpholine, N-cyclohexylmorpholine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetramethylbutanediamine, 30 N,N,N',N'-tetramethylhexane-1,6-diamine, pentamethyldiethylenetriamine, dimethylpiperazine, N-dimethylaminoethylpiperidine, l-azobicyclo[2.2.01octane, 1,4-diazobicyclol2.2.2]octane (Dabco) and alkanolamine compounds such as triethanolamine, triisopropanolamine, 35 N-methyldiethanolamine and N-ethyldiethanolamine, dimethylaminoethanol, 2-(N,N-dimethylaminoethoxy)ethanol, N,N',N''-tris(dialkylaminoalkyl)hexahydrotriazines, eg.
N,N',N''-tris(dimethylaminopropyl)-s-hexahydrotriazine, and triethylenediamine. However, also suitable are metal salts such 40 as iron(II) chloride, zinc chloride, lead octoate, bismuth octoate and preferably tin salts such as tin dioctoate, tin diethylhexanoate and dibutyltin dilaurate and also, in particular, mixtures of tertiary amines and organic tin salts.

Further suitable catalysts are: amidines such as 2,3-dimethyl-3,4,5,6-tetrahydropyrimidine, tetralkylammonium hydroxides such as tetramethylammonium hydroxide, alkali metal BASF Aktiengesellschaft 950948 O.Z. 0050/47248 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 from 10 to 20 carbon atoms and possibly lateral OH groups. Preference is given 5 to using from 0.001 to 5% by weight, in particular from 0.05 to 2% by weight, of catalyst or catalyst combination, based on the weight of the total polyol component.

The polyol components of the invention contain flame retardants.
10 Suitable flame retardants are all those compounds customarily used for this purpose in rigid PUR foams.

Examples which may be mentioned are: diphenyl cresyl phosphate, 15 tricresyl phosphate, triethyl or tributyl phosphate, tris(2-chloroethyl) phosphate, tris(2-chloropropyl) phosphate, tris(1,3-dichloropropyl) phosphate, tetrakis(2-chloroethyl) ethylene diphosphate, diethyl ethanephosphonate and diethyl diethanolaminomethylphosphonate.

Also suitable are bromine-containing flame retardants such as tribromoneopentyl alcohol, reaction products of tribromoneopentyl alcohol, dibromoneopentyl glycol and its reaction products, dibromobutenediol and its reaction products, 2,3-dibromopropanol 25 and its reaction products, tetrabromophthalic anhydride and its reaction products, tribromophenol and its reaction products, tetrabromobisphenol A and its reaction products, bromine-containing phosphoric esters and brominated hydrocarbons.

30 Apart from the compounds mentioned above, it is also possible to use inorganic or organic flame retardants such as red phosphorus, hydrated aluminum oxide, antimony trioxide, arsenic oxide, ammonium polyphosphate and calcium sulfate, expanded graphite or cyanuric acid derivatives such as melamine and expanded graphite 35 and/or aromatic or aliphatic polyesters for making the polyisocyanates polyaddition products flame resistant.

Preferred flame retardants are liquid at room temperature and have a chlorine content of at least 20% by weight or a bromine 40 content of at least 30% by weight or a phosphorus content of at least 5% by weight.

In general, it has been found to be advantageous to use from 10 45 to 80% by weight, preferably from 30 to 60% by weight, of the flame retardants mentioned, based on the weight of the total polyol component.

BASF Aktiengesellschaft 950948 O.Z. 0050/47248 If desired, further auxiliaries and/or additives can be incorporated into the storage-stable, flame retardant-containing polyol components of the present invention. Examples which may be mentioned are surface-active substances, foam stabilizers, cell 5 regulators, fillers, dyes, pigments, hydrolysis inhibitors, fungistatic and bacteriostatic substances.

Suitable surface-active substances are, for example, compounds which serve to aid the homogenization of the starting materials 10 and may also be suitable for regulating the cell structure of the plastics. Examples which may be mentioned are emulsifiers such as the sodium salts of castor oil sulfates or of fatty acids and also amine salts of fatty acids, eg. diethylamine oleate, diethanolamine stearate, diethanolamine ricinoleate, salts of 15 sulfonic acids, eg. alkali metal or ammonium salts of dodecylbenzene- or dinaphthylmethanedisulfonic acid and ricinoleic acid; ~oam stabilizers such as siloxane-oxyalkylene copolymers and other organopolysiloxanes, ethoxylated alkylphenols, ethoxylated fatty alcohols, paraffin oils, castor 20 oil or ricinoleic esters, Turkey red oil and peanut oil, and cell regulators such as paraffins, fatty alcohols and dimethylpolysiloxanes. Furthermore, the above-described oligomeric acrylates having polyoxyalkylene and fluoroalkane radicals as side groups are also suitable for improving the 25 emulsifying action, the cell structure and/or stabilizing the foam. The surface-active substances are usually employed in amounts of from 0.01 to 5% by weight, based on the weight of the total polyol component.

For the purposes of the present invention, fillers, in particular reinforcing fillers, are the customary organic and inorganic fillers, reinforcers, weighting agents, agents for improving the abra~ion behavior in paints, coating compositions, etc. known per 35 se. Specific examples are: inorganic fillers such as siliceous minerals, for example sheet silicates such as antigorite, serpentine, hornblends, amphiboles, chrysotile and talc, metal oxides such as kaolin, aluminum oxides, titanium oxides and iron oxides, metal salts such as chalk, barite and inorganic pigments 40 such as cadmium sulfide and zinc sulfide, and also glass, etc.
Preference is given to using kaolin (china clay), aluminum silicate and coprecipitates of barium sulfate and aluminum silicate and also natural and synthetic fibrous minerals such as wollastonite, metal and, in particular, glass fibers of various 45 lengths, which may be sized. Examples of suitable organic fillers are: carbon, melamine, rosin, cyclopentadienyl resins and graft polymers and also cellulose fibers, polyamide, polyacrylonitrile, CA 022l3l6l l997-08-28 BASF Aktiengesellschaft 950948 O.Z. 0050/47248 polyurethane and polyester fibers based on aromatic and/or aliphatic dicarboxylic esters and, in particular, carbon fibers.

The inorganic and organic fillers can be used individually or as 5 mixtures and are advantageously incorporated into the reaction mixture in amounts of from 0.5 to 50~ by weight, preferably from 1 to 40% by weight, based on the weight of the total polyol component.

Further details regarding the abovementioned customary auxiliaries and additives may be found in the specialist literature, for example the monograph by J.H. Saunders and K.C.
Frisch "High Polymers~ Volume XVI, Polyurethanes, Parts l and 2, 15 Interscience Publishers 1962 and 1964, or the Kunststoff-Handbuch, Polyurethane, Volume VII, Hanser-Verlag, Munich, Vienna, 1st, 2nd and 3rd Editions, 1966, 1983 and 1993.

The storage-stable, flame retardant-contA i n ing polyol components 20 of the present invention are suitable in principle for producing all types of rigid PUR foams by the methods customary per se.

These rigid foams are especially those which contain urethane and/or isocyanurate and/or biuret and/or allophanate and/or 25 uretdione and/or urea and/or carbodiimide groups as characteristic chemical structural elements.

They are prepared by reacting the polyol components of the present invention with organic and/or modified organic 30 polyisocayanates.

Suitable organic and/or modified organic polyisocyanates are the aliphatic, cycloaliphatic, araliphatic and preferably aromatic 35 polyfunctional isocyanates known per se.

Specific examples are: alkylene diisocyanates having from 4 to 12 carbon atoms in the alkylene radical, for example dodecane 1,12-diisocyanate, 2-ethyltetramethylene 1,4-diisocyanate, 40 2-methylpentamethylene 1,5-diisocyanate, tetramethylene 1,4-diisocyanate and preferably hexamethylene 1,6-diisocyanate;
cycloaliphatic diisocyanates such as cyclohexane 1,3- and 1,4-diisocyanate and also any mixtures of these isomers, l-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane 45 (IPDI), hexahydrotolylene 2,4- and 2,6-diisocyanate and also the corresponding isomer mixtures, dicyclohexylmethane 4,4'-,2,2'-and 2,4'-diisocyanate and also the corresponding isomer mixtures, CA 022l3l6l l997-08-28 BASF Aktiengesellschaft 950948 O.Z. 0050/47248 and preferably aromatic diisocyanates and polyisocyanates such as tolylene 2,4- and 2,6-diisocyanate and the corresponding isomer mixtures, diphenylmethane 4,4'-, 2,4'- and 2,2'-diisocyanate and the corresponding isomer mixtures, mixtures of diphenylmethane 5 4,4'- and 2,2'-diisocyanates, polyphenylpolymethylene polyisocyanates, mixtures of diphenylmethane 4,4'-, 2,4'- and 2,2'-diisocyanates and polyphenylpolymethylene polyisocyanates (raw MDI ) and mixtures of raw MDI and tolylene diisocyanates. The organic diisocyanates and polyisocyanates can be used 10 individually or in the form of their mixtures.

Use is frequently also made of modified polyfunctional isocyanates, ie. products which are obtained by chemical reaction of organic diisocyanates and/or polyisocyanates. Examples which 15 may be mentioned are diisocyanates and/or polyisocyanates containing ester, urea, biuret, allophanate, carbodiimide, isocyanurate, uretdione and/or urethane groups. Specific examples of suitable modified organic diisocyanates/polyisocyanates are:
organic, preferably aromatic polyisocyanates containing urethane 20 groups and having NCO contents of from 33.6 to 15% by weight, preferably from 31 to 21% by weight, based on the total weight, diphenylmethane 4,4~-diisocyanate modified with, for example, low molecular weight diols, triols, dialkylene glycols, trialkylene glycols or polyoxyalkylene glycols having molecular weights up to 25 6000, in particular molecular weights up to 1500, modified diphenylmethane 4,4~- and 2,4'-diisocyanate mixtures, modified raw MDI or tolylene 2,4- and 2,6-diisocyanate, with examples of dioxyalkylene or polyoxyalkylene glycols which can be used individually or as mixtures being: diethylene and dipropylene 30 glycols, polyoxyethylene, polyoxypropylene and polyoxypropylene-polyoxyethylene glycols, triols and/or tetrols.
Also suitable are prepolymers contA;ning NCO groups and having NCO contents of from 25 to 3.5% by weight, preferably from 21 to 14% by weight, based on the total weight, and prepared from the 35 polyester and/or preferably polyether polyols mentioned above and diphenylmethane 4,4'-diisocyanate, mixtures of diphenylmethane 2,4'- and 4,4'-diisocyanate, tolylene 2,4- and/or 2,6-diisocyanates or raw MDI . Other modified polyisocyanates which have been found to be useful are liquid polyisocyanates 40 containing carbodiimide groups and/or isocyanurate rings and having NCO contents of from 33.6 to 15% by weight, preferably from 31 to 21% by weight, based on the total weight, eg. those based on diphenylmethane 4,4~-, 2,4~- and/or 2,2~-diisocyanate and/or tolylene 2,4- and/or 2,6-diisocyanate.

BASF Aktiengesellschaft 950948 O.Z. 0050/47248 The modified polyisocyanates can, if desired, be mixed with one another or with unmodified organic polyisocyanates such as diphenylmethane 2,4'- and/or 4,4'-diisocyanate, raw MDI, tolylene 2,4- and/or 2,6-diisocyanate.

Organic polyisocyanates which have been found to be particularly useful and are therefore preferably employed are: mixtures of tolylene diisocyanates and raw MDI or mixtures of modified organic polyisocyanates contAining urethane groups and having an 10 NCO content of from 33,6 to 15% by weight, in particular those based on tolylene diisocyanates, diphenylmethane 4,4'-diisocyanate, diphenylmethane diisocyanate isomer mixtures or raw MDI and, in particular, raw MDI having a diphenylmethane diisocyanate isomer content of from 30 to 80% by weight, 15 preferably from 30 to 60% by weight, in particular from 30 to 55%
by weight.

Apart from the polyol components of the present invention and the organic and/or modified organic polyisocyanates, further auxiliaries and/or additives as are described above can be added to the reaction mixture.

To produce the rigid PUR foams, the organic and/or modified 25 organic polyisocyanates are reacted with the polyol component of the present invention in the presence of, if desired, further auxiliaries and/or additives in such amounts that the equivalence ratio of NCO groups of the polyisocyanates to the sum of the reactive hydrogen atoms of the polyol component is 0.85-1.25:1, 30 preferably 0.95-1.15:1 and in particular 1-1.05:1. If the rigid PUR foams contain at least some bonded isocyanurate groups, a ratio of NCO groups of the polyisocyanates to the sum of the reactive hydrogen atoms of the polyol component of 1.5-60:1, preferably 1.5-8:1, is usually employed.

The rigid PUR foams are advantageously produced by the one-shot process, for example by means of the high-pressure or low-pressure technique in open or closed molds, for example metal molds. Also customary is the continuous application of the 40 reaction mixture onto suitable belts for producing panels.

The isocyanate-based rigid PUR foams of the present invention are preferably produced by the casting or spraying process. In particular, block foaming or mold foaming or continuous 45 manufacture by the double conveyor belt process is employed.

CA 022l3l6l l997-08-28 BASF Aktiengesellschaft 950948 O.Z. 0050/47248 The starting components are usually mixed at from 15 to 90~C, preferably from 20 to 60~C and in particular from 20 to 35~C, and introduced into the open mold or the closed mold which may be under superatmospheric pressure or, in the case of a continuous 5 workstation, applied to a belt which acc~ Ates the reaction mixture. Mixing can be carried out by means of a stirrer or a stirring screw. The mold temperature is advantageously from 20 to 110~C, preferably from 30 to 60~C and in particular from 45 to 50~C.
The rigid PUR foams produced by the process of the present invention have a density of from 0.02 to 0.30 g/cm3, preferably from 0.025 to 0.24 g/cm3 and in particular from 0.03 to 0.1 g/cm3.

They have good mechanical and thermal properties.

The products are preferably used as thermally insulating building material.
The invention is illustrated by means of the following Examples.

Examples 1 to 6 and Comparative Example 1 A base mixture was prepared from the following constituents:

28 parts by mass of polyether alcohol based on sucrose/glycerol/propylene oxide (hydroxyl number 440), 26 parts by mass of polyether alcohol based on glycerol/propylene oxide (hydroxyl number 400), 22 parts by mass of flame retardant trischloropropyl phosphate, 4 parts by mass of flame retardant based on tetrabromophthalic acid/glycol (hydroxyl number 215), 15 parts by mass of flame retardant based on dibromobutenediol~epichlorohydrin/propylene oxide (hydroxyl number 330), 1.5 parts by mass of foam stabilizer based on silicone and 3.5 parts by mass of water.

CA 022l3l6l l997-08-28 BASF Aktiengesellschaft 950948 O.Z. 0050/47248 The final polyol components were prepared from this base mixture by mixing with the additives indicated in Table 1.

Comparative Example 2 In the above-described base mixture, the 3.5 parts by mass of water were replaced by 5 parts by mass of formic acid (98% pure) and 1.5 parts by mass of dimethylcyclohexylamine were added. The lO final polyol component was prepared by mixing the starting materials. The comparatively large amount of formic acid here acts as blowing agent; a stabilizing action does not occur.

Determination of the storage stability The storage stability was determined by storage at 45~C over a period of two weeks. As a measure of the storage stability, the change in the fiber time (thread-drawing time) after storage was determined as a percentage of the fiber time directly after 20 preparation of the polyol component. The fiber time was determined by means of the beaker test, where 42 g of polyol components were mixed with 58 g of raw diphenylmethane diisocyanate (NCO content 31.6%). As the fiber time, the earliest time after which it was possible to draw threads from the rising 25 reaction mixture by means of a glass rod was determined. The fiber times determined are shown in Table 1.

It can be clearly seen from the examples that the formulations containing the stabilizers according to the present invention 30 have a significantly improved storage stability compared with the comparative examples.

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~ m ~ ~ ~ b H ~ ~a BASF Aktiengesellschaft 950948 O.Z. 0050/4724 Examples 7 to 9 5 In each case, two steel cover plates having a thickness of 0.8 mm and dimensions of 1000 mm x 2000 mm were arranged in a press at a spacing of 60 mm. The hollow space between the cover plates was in each case f illed with 5.8 kg of foaming reaction mixture. The reaction mixtures were prepared by mixing, in each case, 2.436 kg lO of the polyol compounds of Examples 1, 4 and 6 with, in each case, 3.364 kg of raw MDI (NCO content: 31.6%). After curing, the sandwich elements were taken from the press.

The components could be used for thermal insulation and met the 15 requirements of the building class Bl in accordance with DIN 4102.

The polyurethane foams produced each had an overall bulk density of 48 kg/m3 and a core density of 45 kg/m3.

Claims

1. A storage-stable, flame retardant-containing polyol component comprising at least one polyol plus, if desired, further relatively high molecular weight compounds containing at least two reactive hydrogen atoms and, if desired, low molecular weight chain extenders and/or crosslinkers and also blowing agents, catalysts, stabilizers and, if desired, further auxiliaries and/or additives, wherein stabilizers used are imidazoles of the general formula , where R1 = C1-C4-alkyl, C1-C4-hydroxyalkyl or dimethylamino-C1-C4-alkyl and R2, R3, R4 = H or C1-C4-alkyl, and/or formic acid.

2. A polyol component as claimed in claim 1, wherein imidazoles used are 1-methylimidazole and/or 1,2-dimethylimidazole.

3. A polyol component as claimed in claim 1, wherein the stabilizer used comprises imidazoles in an amount of from 0.1 to 8% by weight, based on the polyol component.

4. A polyol component as claimed in claim 1, wherein the stabilizer used is formic acid in an amount from 0.01 to 0.5%
by weight, based on the polyol component.

5. A rigid polyurethane foam based on isocyanate and able to be produced by reacting the polyol component as claimed in claim 1 with organic and/or modified organic polyisocyanates.