CA2228969A1 - Production of flame-retardant, isocyanate-based rigid foams - Google Patents
Production of flame-retardant, isocyanate-based rigid foams Download PDFInfo
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- CA2228969A1 CA2228969A1 CA002228969A CA2228969A CA2228969A1 CA 2228969 A1 CA2228969 A1 CA 2228969A1 CA 002228969 A CA002228969 A CA 002228969A CA 2228969 A CA2228969 A CA 2228969A CA 2228969 A1 CA2228969 A1 CA 2228969A1
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
- C08J9/04—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent
- C08J9/12—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a physical blowing agent
- C08J9/14—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a physical blowing agent organic
- C08J9/141—Hydrocarbons
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G18/00—Polymeric products of isocyanates or isothiocyanates
- C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
- C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
- C08G18/65—Low-molecular-weight compounds having active hydrogen with high-molecular-weight compounds having active hydrogen
- C08G18/66—Compounds of groups C08G18/42, C08G18/48, or C08G18/52
- C08G18/6666—Compounds of group C08G18/48 or C08G18/52
- C08G18/6696—Compounds of group C08G18/48 or C08G18/52 with compounds of group C08G18/36 or hydroxylated esters of higher fatty acids of C08G18/38
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G2110/00—Foam properties
- C08G2110/0025—Foam properties rigid
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G2110/00—Foam properties
- C08G2110/0041—Foam properties having specified density
- C08G2110/0058—≥50 and <150kg/m3
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2205/00—Foams characterised by their properties
- C08J2205/10—Rigid foams
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2375/00—Characterised by the use of polyureas or polyurethanes; Derivatives of such polymers
- C08J2375/04—Polyurethanes
Abstract
A process for producing isocyanate-based, flame-retardant rigid foams by reacting a) organic and/or modified organic polyisocyanates with b) at least one higher-molecular-weight compound having at least two reactive hydrogen atoms and, if desired c) low-molecular-weight chain extenders and/or crosslinkers in the presence of d) flame retardants, e) water, f) blowing agents and g) other auxiliaries and/or additives, comprises using, as blowing agents, a mixture of at least one hydrocarbon which is liquid at room temperature and has 5 or more carbon atoms in the molecule with at least one hydrocarbon which is gaseous at room temperature and has 4 or fewer carbon atoms in the molecule.
Description
' BASF Aktienge~ellschaft 960200 O.Z. 0050/47828 Production of flame-retardant, isocyanate-based rigid foams 5 The present invention relates to a process for the production of flame-retardant, isocyanate-based rigid foams which are blown without using fluorochlorohydrocarbons (FCHC), to a blowing agent mixture for the production of these flame-retardant, isocyanate-based rigid foams, and to their use predominantly as 10 insulating materials in the building sector.
Isocyanate-based rigid foams, in particular polyurethane foams and isocyanurate foams, have been known for a long time and are used primarily for heat- or cold-insulation, eg. in cooling 15 devices, in the building sector, in hot water tank and in long-distance heating pipes. Until recently, the blowing agents used to produce these foams were FCHCs, especially trichlorofluoromethane. Because of their destructive effect on the earth~s ozone layer, these materials must be replaced by 20 materials which have no ozone depletion potential (ODP) and a very low global warming potential (GWP).
For these reasons, hydrocarbons have been proposed as the blowing agents of the future. Among the hydrocarbons, the isomers of 25 pentane have a leading role, their relatively low boiling points making them highly suitable as blowing agents for the production of isocyanate-based rigid foams. The use of pentane derivatives has already been mentioned in the 3rd Edition of Kunststoff-Handbuch, ed. G. Becker and D. Braun, Vol. 7, ed.
30 G. Oertel, Carl Hanser Verlag, Munich, Vienna, 1993, eg. on page 115 ff.
The exchange of FCHCs for alternative blowing agents, such as HFCHCs, HFHCs, CO2 and in particular the low-cost hydrocarbons, 35 increases the cost of achieving uniformly good flame-retardant performance. This is especially apparent in higher amounts of flame retardants, which have to be added to the formulations.
Increased amounts of flame retardants create considerable costs and may give inferior foam properties. The search for efficient 40 hydrocarbon-based blowing agents which favorably influence fire performance and therefore require a very small amount of flame retardant to give adequate flame retardancy is therefore an important technical quest.
The use of hydrocarbons as physical blowing agents as alternatives to halogen-containing blowing agents, and in particular the blowing of rigid polyurethane foams using pentane, CA 02228969 19s8-03-1o BASF Aktiengesellschaft 960200 O.Z. 0050/47828 is also described in detail in the publications of Heilig, G., Kunststoffe 81 (1991), pp. 622-625, and Heilig, G. et al., Kunststoffe 81 (1991), pp. 790-794, where there is also reference, inter alia, to the higher proportions of flame 5 retardants which are required.
EP-A-0421269 proposes, inter alia, as a possibility for producing rigid polyurethane foams having low thermal conductivity, blowing agent mixtures of cyclopentane and/or cyclohexane with 10 hydrocarbons having four or fewer carbon atoms. It is preferable here to operate without flame retardants. Increased flame retardancy is not a purpose of the invention described there.
15 Our own Patent Application No. 19526979.9 describes the use, as blowing agents, of cyclopentane and/or other low-boiling hydrocarbons together with low-molecular-weight monofunctional, primary or secondary hydroxyl-containing alcohols, if desired in association with water, for improving the flow behavior in the 20 foaming reaction mixture.
For rigid polyurethane foams having low densities and improved thermal insulation capability, EP-A-0657495 describes, as halogen-free blowing agent mixtures, azeotropic mixtures of 25 cycloaliphatic hydrocarbons having from 5 to 7 carbon atoms with carboxylic esters, ketones or ethers which are liquid at room temperature. Because of their high polarity, the oxygen-containing constituents used in the azeotropic mixtures described dissolve to significant extents in the polyurethane 30 matrix. The resultant plasticizer effect impairs the mechanical properties. In particular in foams having low densities, it creates a tendency to show shrinkage.
It i5 an object of the present invention to discover blowing 35 agents which do not have the stated shortcomings and which advantageously affect the fire performance of the foams.
We have found that this object is achieved, surprisingly, by using, as blowing agents, a mixture of at least one hydrocarbon 40 which is liquid at room temperature and has 5 or more carbon atoms in the molecule with at least one hydrocarbon which is gaseous at room temperature and has 4 or fewer carbon atoms in the molecule.
The invention therefore provides a process for producing flame-retardant, isocyanate-based rigid foams by reacting BASF Aktiengesellschaft 960200 0.~. 0050/47828 a) organic and/or modified organic polyisocyanates with b) at least one higher-molecular-weight compound having at least two reactive hydrogen atoms and, if desired c) low-molecular-weight chain extenders and/or crosslinkers in the presence of d) flame retardants, e) water, f) blowing agents and g) other auxiliaries and/or additives, 20 which comprises using, as blowing agent, a mixture of at least one hydrocarbon which is liquid at room temperature and has 5 or more carbon atoms in the molecule with at least one hydrocarbon which is gaseous at room temperature and has 4 or fewer carbon atoms in the molecule.
The invention also provides a blowing agent mixture for the production of flame-retardant isocyanate-based rigid foams and their use as insulating material in the building sector.
A particularly surprising discovery was that the additional use of the highly flammable, gaseous hydrocarbons having four or fewer carbon atoms, which also include the high-energy fuels well known as liquified petroleum gases, reduces the combustibility of 35 the foams.
From the class consisting of hydrocarbons which are liquid at room temperature and have five or more carbon atoms in the molecule, cyclic and noncyclic representatives may be used. The 40 desired effects are achieved with the use of alkanes and alkenes.
Preference is given to those having five or six carbon atoms, such as n-hexane and its isomers, 1-, 2- and 3-hexene and its isomers, cyclohexane and methylcyclohexane. Particularly advantageous and therefore particularly preferred hydrocarbons 45 are n-pentane, isopentane, neopentane and cyclopentane.
BASF Aktiengesell~chaft 960200 O.Z. 0050/47828 It is, however, also possible to use other liquid hydrocarbons, in particular alkanes and alkenes and their isomers which have from seven to ten carbon atoms in the molecule, for example n-heptane, n-octane, n-nonane, n-decane and their isomers, 5 methylcyclohexane, the isomers of dimethylcyclohexane and the isomers of heptene, octene, nonene and decene.
These liquid hydrocarbons may be used individually or in mixtures with one another.
From the class consisting of hydrocarbons which are gaseous at room temperature and have four or fewer carbon atoms in the molecule, preference is given to those having three or four 15 carbon atoms, for example propane, cyclopropane, propene, cyclobutane, l-butene, cis- and trans-2-butene, isobutene and methylcyclopropane. Use of n-butane and isobutane is particularly preferred.
20 It is also possible, however, to use methane, ethane and ethene.
These gaseous hydrocarbons may be used alone or in mixtures with one another.
25 The hydrocarbons which are liquid at room temperature-and have 5 or more carbon atoms in the molecule are preferably used in an amount of from 0.1 to 10% by weight, particularly preferably in an amount of from 2 to 6% by weight, based on the total amount of the foam.
The hydrocarbons which are gaseous at room temperature and have 4 or fewer carbon atoms in the molecule are preferably used in an amount of from 0.1 to 10% by weight, particularly preferably in 35 an amount of from 2 to 6% by weight, based on the total amount of the foam.
For producing the flame-retardant, isocyanate-based rigid foams according to the invention, it is preferable to use a blowing 40 agent mixture consisting of a mixture of a number of hydrocarbons which are liquid at room temperature and have 5 or more carbon atoms in the molecule with a number of hydrocarbons which are gaseous at room temperature and have 4 or fewer carbon atoms in the molecule; this blowing agent mixture develops its blowing 45 effect alongside the carbon dioxide produced from water and isocyanate.
BASF Aktiengesellschaft 960200 O.Z. 0050/47828 The mixture of hydrocarbons which are liquid at room temperature and have 5 or more carbon atoms in the molecule with hydrocarbons which are gaseous at room temperature and have 4 or fewer carbon atoms in the molecule may be prepared separately by prior mixing 5 of these components, for example in an autoclave under pressure.
Thi~ mixture iB then preferably added to the polyol component in a conventional manner. It is also possible to meter the hydrocarbon components individually into the material stream, preferably into the polyol component, immediately before it is 10 passed to the mixing head for the mixing of polyol component and isocyanate component. Metering into a specific multicomponent mixing head is also possible. The handling of the hydrocarbons with pumps, metering apparatus and storage vessels is carried out in a known manner.
The flame-retardant, isocyanate-based rigid foams according to the invention are produced by reacting, in a manner known per se, 20 a) organic and/or modified organic polyisocyanates with b) at least one higher-molecular-weight compound having at least two reactive hydrogen atoms and, if desired 25 c) low-molecular-weight chain extenders and/or crosslinkers in the presence of 30 d) flame retardants, e) water, f) the novel blowing agent mixture and g) other auxiliaries and/or additives.
These isocyanate-based rigid foams are especially those which contain urethane groups and/or isocyanurate groups and/or biuret 40 groups and/or allophanate groups and/or uretdione groups and/or urea groups and/or carbodiimide groups as characteristic chemical structural elements.
BASF Aktiengesellschaft 960200 O.Z. 0050/47828 With the exception of the blowing agents (d), the constituents used for producing the isocyanate-based rigid foams in the novel process are known per se, and are individually described below.
5 a) Suitable organic polyisocyanates are the aliphatic, cycloaliphatic, araliphatic and preferably aromatic polyfunctional isocyanates known per se.
Specific examples are: alkylene diisocyanates having from 4 to 12 carbon atoms in the alkylene radical, such as dodecane 1,12-diisocyanate, 2-ethyltetramethylene 1,4-diisocyanate, 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 any desired mixtures of these isomers, l-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate), 2,4- and 2,6-hexahydrotolylene diisocyanate and the corresponding isomer mixtures, dicyclohexylmethane 4,4'-, 2,2'- and 2,4'-diisocyanate and the corresponding isomer mixtures, and preferably aromatic di- 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 4,4'- and 2,4'-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 di- and polyisocyanates can be used individually or in the form of their mixtures.
Use is also frequently made of modified polyfunctional isocyanates, ie. products obtained by chemical reaction of organic di- and/or polyisocyanates. Examples are di- and/or polyisocyanates containing ester groups, urea groups, biuret groups, allophanate groups, carbodiimide groups, isocyanurate groups, uretdione groups and/or urethane groups. Specific examples are: organic, preferably aromatic, polyisocyanates containing urethane 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, for example with low-molecular-weight diols, triols, dialkylene glycols, trialkylene glycols or polyoxyalkylene glycols having molecular weightR of up to 6000, in particular having molecular weights up to 1500, modified diphenylmethane BASF Aktiengesellschaft 960200 O.Z. 0050/47828 4,4'-diisocyanate, modified diphenylmethane 4,4'- and 2,4~-diisocyanate mixtures, modified raw MDI or tolylene 2,4-and~or 2,6-diisocyanate, examples of dialkylene or polyoxyalkylene glycols, which may be used individually or as mixtures, are: diethylene, dipropylene, polyoxyethylene, polyoxypropylene and polyoxypropylene-polyoxyethylene glycols, and the corresponding triols and/or tetrols. Other suitable compounds are prepolymers containing 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 polyester polyols and/or preferably polyether polyols described below 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. Liquid polyisocyanates 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, for example those based on diphenylmethane 4,4'-, 2,4'- and/or 2,2'-diisocyanate and~or tolylene 2,4- and~or 2,6-diisocyanate have also proven useful.
The modified polyisocyanates may, if desired, be mixed with one another or with unmodified organic polyisocyanates, such as diphenylmethane 2,4'- or 4,4'-diisocyanate, raw MDI, tolylene 2,4- and/or 2,6-diisocyanate.
Organic polyisocyanates which have proven especially useful are diphenylmethane diisocyanate isomer mixtures or raw MDI
having a diphenylmethane diisocyanate isomer content of from 33 to 55% by weight, and polyisocyanate mixtures containing urethane groups and based on diphenylmethane diisocyanate having an NCO content of from 15 to 33% by weight.
b) Higher-molecular-weight compounds (b) having at least two reactive hydrogen atoms are expediently those having a functionality of from 2 to 8, preferably from 2 to 6, and a molecular weight of from 300 to 8000, preferably from 300 to 3000. Examples of compounds which have proven useful are polyether polyamines and/or preferably polyols selected from the class consisting of polyether polyols, polyester polyols, polythioether polyols, polyesteramides, hydroxyl-containing polyacetals, hydroxyl-containing aliphatic polycarbonates and mixtures of at least two of the polyols mentioned. Preference is given to the use of polyester polyols and/or polyether polyols. The hydroxyl number of the polyhydroxy compounds BASF Aktiengesellschaft 960200 O.Z. 0050/47828 here is generally from 150 to 850 mg KOH/g and preferably from 200 to 600 mg KOH/g.
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 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 here may also be used either in mixtures with one another or individually. The corresponding dicarboxylic acid derivatives, such as dicarboxylic esters of alcohols having from 1 to 4 carbon atoms or dicarboxylic anhydrides may also be used instead of the free dicarboxylic acids. Preference is given to the use of dicarboxylic acid mixtures of succinic, glutaric and adipic acid in a mixing ratio of, for example, from 20 to 35 : from 35 to 50 : from 20 to 32 parts by weight, and in particular adipic acid.
Examples of di- and polyhydric alcohols, in particular diols, are: ethanediol, diethylene glycol, 1,2- and 1,3-propanediol, dipropylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,10-decanediol, 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 diols mentioned, in particular mixtures of 1,4-butanediol, 1,5-pentanediol and 1,6-hexanediol. Polyester polyols, derived from lactones, such as ~-caprolactone, or hydroxycarboxylic acids, such as ~-hydroxycaproic acid, may also be used.
To prepare the polyester polyols, the organic, for example aromatic, and preferably aliphatic, polycarboxylic acids andlor their derivatives and polyhydric alcohols may be polycondensed without catalysts or preferably in the presence of esterification catalysts, expediently in an atmosphere of inert gas, such as nitrogen, carbon monoxide, helium, argon etc., in melt form at from 150 to 250~C, preferably from 180 to 220~C, under reduced pressure if desired, to the desired acid number of advantageously less than 10, preferably less than 2. In a preferred embodiment, the esterification mixture is polycondensed at the abovementioned temperatures to an acid number of from 80 to 30, preferably from 40 to 30, at atmospheric pressure and then under a pressure of less than BASF Aktiengesellschaft 960200 O.Z. 0050/47828 500 mbar, preferably from 50 to 150 mbar. Examples of suitable esterification catalysts are iron, cadmium, cobalt, lead, zinc, antimony, maqnesium, titanium and tin, in the form of metals, metal oxides or metal salts. The polycondensation may, however, also be carried out in liquid phase in the presence of diluents and/or entrainers, such as benzene, toluene, xylene or chlorobenzene, for removal of the water of condensation by azeotropic distillation.
To prepare the polyester polyols, the organic polycarboxylic acids and/or their derivatives and polyhydric alcohols are polycondensed advantageously in a molar ratio of 1: from 1 to 1.8, preferably 1: from 1.05 to 1.2.
The resultant polyester polyols preferably have a functionality of 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 used in particular are polyether polyols prepared by known processes from one or more alkylene oxides having from 2 to 4 carbon atoms in the alkylene radical for example by anionic polymerization using alkali metal hydroxides, such as sodium hydroxide or potassium hydroxide, or alkali metal alkoxides, such as sodium methoxide, sodium ethoxide, potassium ethoxide or potassium isopropoxide as catalysts and with addition of at least one initiator molecule having from 2 to 8, preferably from 2 to 6, reactive hydrogen atoms in its structure, or by cationic polymerization using Lewis acids, such as antimony pentachloride, boron fluoride etherate, etc., or bleaching earth as catalysts.
Examples of suitable alkylene oxides are tetrahydrofuran, 1,3-propylene oxide, 1,2- and 2,3-butylene oxide, styrene oxide and preferably ethylene oxide and 1,2-propylene oxide.
The alkylene oxides may be used individually, alternating in sequence or as mixtures. Examples of initiator molecules are:
water, organic dicarboxylic acids, such as succinic acid, adipic acid, phthalic acid and terephthalic acid, aliphatic and aromatic diamines, which may be unsubstituted or have N-mono-, N,N- or N,N~-dialkyl substitution, having from 1 to 4 carbon atoms in the alkyl radical, such as unsubstituted or mono- or dialkyl-substituted ethylenediamine, diethylenetriamine, triethylenetetramine, 1,3-propylenediamine, 1,3- or 1,4-butylenediamine, 1,2-, BASF Aktienge~ell~chaft 960200 O.Z. 0050~47828 1,3-, 1,4-, 1,5- or 1,6-hexamethylenediamine, phenylenediamine, 2,3-, 2,4- or 2,6-tolylenediamine, 4,4~-, 2,4~- or 2,2'-diaminodiphenylmethane.
Other initiator molecules which are suitable are:
alkanolamines, such as ethanolamine and N-methyl- and N-ethylethanolamine, dialkanolamines, such as diethanolamine and N-methyl- and N-ethyldiethanolamine, and trialkanolamines, such as triethanolamine, and ammonia.
Preference is given to the use of polyhydric, in particular di- and/or trihydric alcohols, such as ethanediol, 1,2-propanediol, 1,3-propanediol, diethylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, glycerol, trimethylolpropane, pentaerythritol, sorbitol and sucrose.
The polyether polyols, preferably polyoxypropylene polyols and polyoxypropylene-polyoxyethylene polyols, have a functionality of preferably from 2 to 6 and in particular from 2 to 4, and molecular weights of from 300 to 3000, preferably from 300 to 2000, and in particular from 400 to 2000, and suitable 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 and 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, expediently in the abovementioned polyether polyols, using as a basis the information 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 polyether polyol dispersions which contain, for example, as disperse phase, usually in an amount of from 1 to 50% by weight, preferably from 2 to 25%
by weight, examples being polyureas, polyhydrazides, melamine and/or polyurethanes containing bonded tertiary amino groups, and which are described, for example, in EP-B-011 752 (US 4 304 708), US-A-4 374 209 and DE-A-32 31 497.
The polyether polyols may, like the polyester polyols, be used individually or in the form of mixtures. They may also be mixed with the graft polyether polyols or polyester BASF Aktiengesellschaft 960200 O.Z. 0050/47828 polyols and with the hydroxyl-containing polyester amides, polyacetals, polycarbonates and/or polyether polyamines.
Examples of hydroxyl-containing polyacetals are the compounds which can be prepared from glycols, such as diethylene glycol, triethylene glycol, 4,4'-dihydroxyethoxy-diphenyldimethylmethane or hexanediol and formaldehyde.Suitable polyacetals may also be prepared by polymerizing cyclic acetals.
Suitable hydroxyl-containing polycarbonates are those of the 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, such as diphenyl carbonate, or phosgene.
Examples of polyester amides are the pre~ in~ntly linear condensates which are obtained from polybasic, saturated and/or unsaturated carboxylic acids and/or their anhydrides and polyhydric saturated and/or unsaturated aminoalcohols or mixtures of polyhydric alcohols and aminoalcohols and/or polyamines.
Suitable polyether polyamines can be prepared from the abovementioned polyether polyols by known processes, for example the cyanoalkylation of polyoxyalkylene polyols followed by hydrogenation of the resultant nitrile (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).
c) The isocyanate-based rigid foams may be produced with or without the additional use of chain extendPrs and/or crosslinkers. The addition of chain extenders, crosslinkers or else, if desired, mixtures of these can prove advantageous, however, for modifying the mechanical properties, for example the rigidity. Chain extenders and/or crosslinkers which are used are diols and/or triols having molecular weights of less than 400, preferably from 60 to 300. Examples of these are aliphatic, cycloaliphatic and/or araliphatic diols having from 2 to 14, preferably from 4 to 10, carbon atoms, such as ethylene glycol, 1,3-propanediol, l,10-decanediol, o-, m- and p-dihydroxycyclohexane, diethylene glycol, dipropylene glycol and preferably 1,4-butanediol, 1,6-hexanediol and bis(2-hydroxyethyl)-CA 02228969 1998-03-lo BASF Aktienge~ellschaft 960200 O.Z. 0050/47828 hydroquinone, triols, such as 1,2,4- and 1,3,5-trihydroxycyclohexane, glycerol and trimethylolpropane, and low-molecular-weight hydroxyl-containing polyalkylene oxides based on ethylene oxide and/or 1,2-propylene oxide and the abovementioned diols and/or triols as initiator molecules.
If chain extenders, crosslinkers or mixtures of these are used for producing the isocyanate-based rigid foams, these are expediently used in an amount of from 0 to 20% by weight, preferably from 2 to 8% by weight, based on the weight of component (b).
15 d) The isocyanate-based rigid foams according to the invention are flame-retardant. The flame retardants used may be any of the usual materials used for this purpose in polyurethane chemistry. Halogen compounds and phosphorus compounds are predominantly used.
Examples of suitable flame retardants are tricresyl phosphate, tris~2-chloroethyl) phosphate, tris(2-chloropropyl) phosphate, tris(1,3-dichloropropyl) phosphate, tris(2,3-dibromopropyl) phosphate, tetrakis(2-chloroethyl) ethylene diphosphate, dimethyl methanephosphonate, diethyl diethanolaminomethylphosphonate and commercially available halogen-containing flame-retardant polyols.
Since the isocyanate-based rigid foam of the future should be produced only using halogen-free additives, the flame retardants should also be halogen-free. Examples of these are derivatives of phosphoric acid, phosphorous acid or phosphonic acid and which are reactive to isocyanate; these may, if desired, be combined with non-reactive liquid and/or solid halogen-free flame retardants, eg. those made from organic derivatives of phosphoric acid, phosphonic acid or phosphorous acid and/or from salts of phosphoric acid.
Besides the abovementioned materials, use may also be made of inorganic or organic flame retardants such as red phosphorus, alumina hydrate, antimony trioxide, arsenic oxide, ammonium polyphosphate and calcium sulfate, expandable graphite or cyanuric acid derivativqs, such as melamine, or mixtures of at least two flame retardants, such as ammonium BASF Aktiengesell~chaft 960200 O.Z. 0050/47828 polyphosphates and melamine and, if desired, maize starch or ammonium polyphosphate, melamine and expandable graphite.
Particular preference is given to tris(2-chloropropyl) phosphate, phosphonic acid derivatives, ammonium polyphosphate and expandable graphite.
The use of the novel halogen-free blowing agent mixture (f) of liquid and gaseous hydrocarbons avoids the use of unnecessarily large amounts of hydrocarbon and thus makes an indirect contribution to flame retardancy. It has generally proven expedient to use from 5 to 50 parts by weight, preferably from 5 to 25 parts by weight, of the abovementioned flame retardants for each 100 parts by weight of component (b).
e) Water is used as chemical blowing agent and reacts with isocyanate groups of component (a) with formation of carbon dioxide. The water is preferably added to component (b) in an amount of from 0.5 to 5% by weight, based on the weight of component (b). The addition of water may be combined with the use of the blowing agents to be used according to the invention.
f) For producing the isocyanate-based, flame-retardant rigid foams use is made, according to the invention, as described above, of a blowing agent mixture consisting of a mixture of at least one non-cyclic hydrocarbon which is liquid at room temperature and has 5 or more carbon atoms in the molecule and at least one hydrocarbon which is gaseous at room temperature and has 4 or fewer carbon atoms in the molecule.
As likewise described above, the novel blowing agent mixture is advantageously introduced into the polyol component consisting of the formative components (b), (d), (e), the catalysts (g) and, if desired, (c) and other auxiliaries and/or additives (g), or the hydrocarbons are metered in individually.
40 g) For producing the flame-retardant rigid foams, use is usually made of catalysts and, if desired, other auxiliaries and/or additives.
Compounds used as catalysts (g) are in particular those which bring about a pronounced acceleration of the reaction of the compounds of component (b) which contain reactive hydrogen atoms, in particular hydroxyl groups, and (c) if used, with BASF Aktiengesellschaft 960200 O.Z. 0050/47828 the organic, unmodified or modified polyisocyanates (a). By means of suitable catalysts (g), the isocyanate groups may, however, also be induced to react with one another, giving preferably isocyanurate structures, besides the adducts between isocyanates (a) and the compounds (b) having groups with active hydrogen.
The catalysts used are therefore in particular those which accelerate reactions of the isocyanates, especially urethane, urea and isocyanurate formation.
Preferred compounds for this purpose are tertiary amines, tin compounds, bismuth compounds, alkali metal carboxylates, alkaline-earth metal carboxylates, quaternary ammonium salts, s-hexahydrotriazines and tris(dialkylA inf ?thyl)phenols.
Examples of suitable catalysts are organometallic compounds, preferably organotin compounds, such as tin(II) salts of organic carboxylic acids, e.g. tin(II) acetate, tin~II) octoate, tin(II) ethylhexoate and tin(II) laurate, and the dialkyltin(IV) salts of organic carboxylic acids, such as dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate and dioctyltin diacetate. The organometallic compounds are used alone or preferably in combination with strongly basic amines, for example amidines, such as 2,3-dimethyl-3,4,5,6-tetrahydropyrimidine, tertiary amines, such as triethylamine, tributylamine, dimethylbenzylamine, N-methyl-, N-ethyl- and N-cyclohexylmorpholine, N, N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetramethylbutanediamine, N, N~N~N~-tetramethyl-1~6-hexanediamine~
pentamethyldiethylenetriamine, tetramethyldiaminoethyl ether, bis(dimethylaminopropyl)urea, dimethylpiperazine, 1,2-dimethylimidazole, 1-azabicyclo[3.3.0]octane and preferably 1,4-diazabicyclo[2.2.2~octane, and alkanolamine compounds, 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, 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 alkali metal salts of long-chain fatty acids having from 10 to 20 carbon atoms and with or BASF Aktiengesellschaft 960200 O.Z. 0050/47828 without OH side groups. It is preferable to use 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 component (b).
Further auxiliaries and/or additives (g) may, if desired, also be incorporated into the reaction mixture for producing the isocyanate-based rigid foams according to the invention in addition to the catalysts. Examples of these are surfactants, foam stabilizers, cell regulators, fillers, dyes, pigments, agents to protect against hydrolysis and substances with fungistatic and bacteriostatic action.
Examples of suitable surfactants are compounds which serve to promote the homogenization of the starting materials and, if desired, are also suitable for regulating the cell structure of the plastics. Examples of these are emulsifiers, such as the sodium salts of castor oil sulfates, or of fatty acids, and salts of fatty acids with amines, such as diethylamine oleate, diethanolamine stearate, diethanolamine ricinoleate, salts of sulfonic acids, such as alkali metal or ammonium salts of dodecylbenzene- or dinaphthylmethanedisulfonic acid and ricinoleic acid; foam stabilizers, such as siloxane-oxalkylene copolymers and other organopolysiloxanes, oxethylated alkyl phenols, oxethylated fatty alcohols, paraffin oils, castor oil esters, ricinoleic acid esters, Turkey red oil and groundnut oil, and cell regulators, such as paraffins, fatty alcohols and dimethylpolysiloxanes.
Suitable compounds for improving the emulsification action, the cell structure and/or stabilizing the foam are furthermore the oligomeric acrylates having polyoxyalkylene and fluoroalkane radicals as side groups as described above.
The surfactants are usually used in amounts from 0.01 to 5 parts by weight, based on 100 parts by weight of component (b)-The term fillers, in particular reinforcing fillers, is takento mean the usual organic and inorganic fillers, reinforcing agents, weighting agents, agents for improving the abrasion behavior in paints, coating agents, etc. which are known per se. Specific examples are: inorganic fillers, such as silicate minerals, for example phyllosilicates, such as antigorite, serpentine, hornblendes, 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, such as cadmium sulfide, zinc sulfide and glass, etc. Preference is given to the use of BASF Aktiengesellschaft 960200 O.Z. 0050/47828 kaolin (china clay), aluminum silicate and coprecipitates of barium sulfate and aluminum silicate, and natural and synthetic fibrous minerals, such as wollastonite, metal fibers and in particular glass fibers of various lengths, which may be provided with a size if desired. Examples of organic fillers are: starch, carbon, melamine, colophony, cyclopentadienyl resins, graft polymers, cellulose fibers, polyamide fibers, polyacrylonitrile fibers, polyurethane fibers, polyester fibers based on aromatic and/or aliphatic dicarboxylic acid esters, and in particular carbon fibers.
The inorganic and organic fillers may be used individually or as 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 components (a) to ~c), where, however, the content of mats, nonwovens and wovens made from natural and synthetic fibers may reach values of up to 80.
Further details concerning the abovementioned further starting materials may be found in the specialist literature, for example in the Monograph of H.J. Saunders and K.C. Frisch, High Polymers, Vol. XVI, Polyurethanes, Parts 1 and 2, Interscience Publishers 25 1962 and 1964, or the Kunststoffhandbuch as mentioned above, Polyurethane, Vol. VII, Carl Hanser Verlag, Munich, Vienna, 1st, 2nd and 3rd editions, 1966, 1983 and 1993.
For producing the isocyanate-based rigid foams, the organic 30 and/or modified organic polyisocyanates ~a), higher-molecular-weight compounds having at least two reactive hydrogen atoms (b) and, if desired, chain extenders and/or crosslinkers (c) are reacted in amounts giving an equivalents ratio of NC0 groups in the polyisocyanates (a) to the total of 35 the reactive hydrogen atoms in components (b) and, if used, (c) of 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 isocyanate-based rigid foams contain, at least to some extent, isocyanurate groups in their structures, the ratio of NC0 groups in the polyisocyanates ~a) to 40 the total of the reactive hydrogen atoms in component (b) and, if used, (c) is usually from 1.5 to 60:1, preferably from 3 to 8:1.
The isocyanate-based rigid foams according to the invention are preferably produced by the casting or spraying process, using in 45 particular block foaming or mold foaming or continuous production in the double belt conveyor process. It is advantageous to operate with the one-shot process, for example using the BASF Aktienge8ellschaft 960200 O.Z. 0050/47828 high-pressure or low-pressure technique, in open or closed molds.
It has proven especially advantageous to operate with the two-component process and to combine the formative components (b), ~d), (e), (f) and catalysts (g) and, if used, (c) and other 5 auxiliaries and/or additives (g) in the component (A) and to use the organic polyisocyanates and/or modified polyisocyanates (a) or mixtures of these polyisocyanates and, if desired, blowing agent (f) as the component (B).
lO The starting components are mixed at from 15 to 90~C, preferably from 20 to 60~C, in particular from 20 to 35~C, and introduced into the open mold or, if desired, under elevated pressure into the closed mold. The mixing can, as already stated, be carried out mechanically using a spiral mixer or other agitator. The mold 15 temperature is expediently 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 poYsible to use more foam-forming 20 reaction mixture than is required for complete filling of the mold, this then gives compressed foams.
The rigid polyurethane foams or rigid molded foams produced by the novel process have a density of from 0.02 to 0.75 g/cm3, 25 preferably from 0.025 to 0.24 g~cm3, and in particular from 0.03 to 0.1 g/cm3.
The products are preferably used as thermally insulating building materials.
The invention will be described in greater detail using the following working examples:
35 Working Examples 1 - 4 and Comparative Examples 1 - 2:
The following polyol blend (polyol) was prepared for the formulations given in Table 1 for the examples and comparative examples:
Polyetheralcohol based on48 parts by weight sorbitol/propylene oxide, hydroxyl number 355 mg KOH/g, Polyethylene glycol,5 parts by weight BASF Aktienge~ell~chaft 960200 O.Z. 0050/47828 Hydroxyl number 190 mg KOH~g, Castor oil, 15 parts by weight Hydroxyl number 165 mg KOH/g, Trischloropropyl phosphate, 20 parts by weight Diphenyl cresyl phosphate, 10 parts by weight Organosilicon-based foam 2 parts by weight stabilizer (DABCO DC 193, Air Products), 15 The following physical blowing agents were used for the examples and comparative examples;
Blowing agent 1 (according to the invention):
n-Pentane 68 parts by weight Isopentane7 parts by weight n-Butane 10 parts by weight Isobutane 5 parts by weight Blowing agent 2 (according to the invention):
Cyclopentane 72 parts by weight n-Butane 28 parts by weight Blowing agent 3 (according to the invention):
n-Pentane70 parts by weight Isopentane8 parts by weight n-Butane 7 parts by weight Isobutane4 parts by weight Propane 1 part by weight Blowing agent 4 (comparative):
n-Pentane 80 parts by weight Isopentane20 parts by weight BASF Aktienge~ellschaft 960200 O.Z. 0050/47828 Blowing agent 5 (comparative);
Cyclopentane 100 parts by weight.
To produce the rigid polyurethane polyisocyanurate foams, in each case a charge of 500 g of the formulations shown in Table 1 was prepared in a mixing vessel and 480 g of this material were transferred into a lidded foam mold of dimensions 210 x 210 x 200 mm, an overall density of the foam of about 55 g/dm3 being achieved at a compaction of about lO percent. After a hardening time of one hour, the foam was removed from the mold and the fire performance was determined according to DIN 4102 24 hours after production.
The results of the fire test are given in the lower part of the table and show the improved fire performance obtained on using the novel blowing agents.
20 The blowing effect of the novel blowing agent mixtures is better than that obtained from the sole use of hydrocarbons which are liquid at room temperature.
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Isocyanate-based rigid foams, in particular polyurethane foams and isocyanurate foams, have been known for a long time and are used primarily for heat- or cold-insulation, eg. in cooling 15 devices, in the building sector, in hot water tank and in long-distance heating pipes. Until recently, the blowing agents used to produce these foams were FCHCs, especially trichlorofluoromethane. Because of their destructive effect on the earth~s ozone layer, these materials must be replaced by 20 materials which have no ozone depletion potential (ODP) and a very low global warming potential (GWP).
For these reasons, hydrocarbons have been proposed as the blowing agents of the future. Among the hydrocarbons, the isomers of 25 pentane have a leading role, their relatively low boiling points making them highly suitable as blowing agents for the production of isocyanate-based rigid foams. The use of pentane derivatives has already been mentioned in the 3rd Edition of Kunststoff-Handbuch, ed. G. Becker and D. Braun, Vol. 7, ed.
30 G. Oertel, Carl Hanser Verlag, Munich, Vienna, 1993, eg. on page 115 ff.
The exchange of FCHCs for alternative blowing agents, such as HFCHCs, HFHCs, CO2 and in particular the low-cost hydrocarbons, 35 increases the cost of achieving uniformly good flame-retardant performance. This is especially apparent in higher amounts of flame retardants, which have to be added to the formulations.
Increased amounts of flame retardants create considerable costs and may give inferior foam properties. The search for efficient 40 hydrocarbon-based blowing agents which favorably influence fire performance and therefore require a very small amount of flame retardant to give adequate flame retardancy is therefore an important technical quest.
The use of hydrocarbons as physical blowing agents as alternatives to halogen-containing blowing agents, and in particular the blowing of rigid polyurethane foams using pentane, CA 02228969 19s8-03-1o BASF Aktiengesellschaft 960200 O.Z. 0050/47828 is also described in detail in the publications of Heilig, G., Kunststoffe 81 (1991), pp. 622-625, and Heilig, G. et al., Kunststoffe 81 (1991), pp. 790-794, where there is also reference, inter alia, to the higher proportions of flame 5 retardants which are required.
EP-A-0421269 proposes, inter alia, as a possibility for producing rigid polyurethane foams having low thermal conductivity, blowing agent mixtures of cyclopentane and/or cyclohexane with 10 hydrocarbons having four or fewer carbon atoms. It is preferable here to operate without flame retardants. Increased flame retardancy is not a purpose of the invention described there.
15 Our own Patent Application No. 19526979.9 describes the use, as blowing agents, of cyclopentane and/or other low-boiling hydrocarbons together with low-molecular-weight monofunctional, primary or secondary hydroxyl-containing alcohols, if desired in association with water, for improving the flow behavior in the 20 foaming reaction mixture.
For rigid polyurethane foams having low densities and improved thermal insulation capability, EP-A-0657495 describes, as halogen-free blowing agent mixtures, azeotropic mixtures of 25 cycloaliphatic hydrocarbons having from 5 to 7 carbon atoms with carboxylic esters, ketones or ethers which are liquid at room temperature. Because of their high polarity, the oxygen-containing constituents used in the azeotropic mixtures described dissolve to significant extents in the polyurethane 30 matrix. The resultant plasticizer effect impairs the mechanical properties. In particular in foams having low densities, it creates a tendency to show shrinkage.
It i5 an object of the present invention to discover blowing 35 agents which do not have the stated shortcomings and which advantageously affect the fire performance of the foams.
We have found that this object is achieved, surprisingly, by using, as blowing agents, a mixture of at least one hydrocarbon 40 which is liquid at room temperature and has 5 or more carbon atoms in the molecule with at least one hydrocarbon which is gaseous at room temperature and has 4 or fewer carbon atoms in the molecule.
The invention therefore provides a process for producing flame-retardant, isocyanate-based rigid foams by reacting BASF Aktiengesellschaft 960200 0.~. 0050/47828 a) organic and/or modified organic polyisocyanates with b) at least one higher-molecular-weight compound having at least two reactive hydrogen atoms and, if desired c) low-molecular-weight chain extenders and/or crosslinkers in the presence of d) flame retardants, e) water, f) blowing agents and g) other auxiliaries and/or additives, 20 which comprises using, as blowing agent, a mixture of at least one hydrocarbon which is liquid at room temperature and has 5 or more carbon atoms in the molecule with at least one hydrocarbon which is gaseous at room temperature and has 4 or fewer carbon atoms in the molecule.
The invention also provides a blowing agent mixture for the production of flame-retardant isocyanate-based rigid foams and their use as insulating material in the building sector.
A particularly surprising discovery was that the additional use of the highly flammable, gaseous hydrocarbons having four or fewer carbon atoms, which also include the high-energy fuels well known as liquified petroleum gases, reduces the combustibility of 35 the foams.
From the class consisting of hydrocarbons which are liquid at room temperature and have five or more carbon atoms in the molecule, cyclic and noncyclic representatives may be used. The 40 desired effects are achieved with the use of alkanes and alkenes.
Preference is given to those having five or six carbon atoms, such as n-hexane and its isomers, 1-, 2- and 3-hexene and its isomers, cyclohexane and methylcyclohexane. Particularly advantageous and therefore particularly preferred hydrocarbons 45 are n-pentane, isopentane, neopentane and cyclopentane.
BASF Aktiengesell~chaft 960200 O.Z. 0050/47828 It is, however, also possible to use other liquid hydrocarbons, in particular alkanes and alkenes and their isomers which have from seven to ten carbon atoms in the molecule, for example n-heptane, n-octane, n-nonane, n-decane and their isomers, 5 methylcyclohexane, the isomers of dimethylcyclohexane and the isomers of heptene, octene, nonene and decene.
These liquid hydrocarbons may be used individually or in mixtures with one another.
From the class consisting of hydrocarbons which are gaseous at room temperature and have four or fewer carbon atoms in the molecule, preference is given to those having three or four 15 carbon atoms, for example propane, cyclopropane, propene, cyclobutane, l-butene, cis- and trans-2-butene, isobutene and methylcyclopropane. Use of n-butane and isobutane is particularly preferred.
20 It is also possible, however, to use methane, ethane and ethene.
These gaseous hydrocarbons may be used alone or in mixtures with one another.
25 The hydrocarbons which are liquid at room temperature-and have 5 or more carbon atoms in the molecule are preferably used in an amount of from 0.1 to 10% by weight, particularly preferably in an amount of from 2 to 6% by weight, based on the total amount of the foam.
The hydrocarbons which are gaseous at room temperature and have 4 or fewer carbon atoms in the molecule are preferably used in an amount of from 0.1 to 10% by weight, particularly preferably in 35 an amount of from 2 to 6% by weight, based on the total amount of the foam.
For producing the flame-retardant, isocyanate-based rigid foams according to the invention, it is preferable to use a blowing 40 agent mixture consisting of a mixture of a number of hydrocarbons which are liquid at room temperature and have 5 or more carbon atoms in the molecule with a number of hydrocarbons which are gaseous at room temperature and have 4 or fewer carbon atoms in the molecule; this blowing agent mixture develops its blowing 45 effect alongside the carbon dioxide produced from water and isocyanate.
BASF Aktiengesellschaft 960200 O.Z. 0050/47828 The mixture of hydrocarbons which are liquid at room temperature and have 5 or more carbon atoms in the molecule with hydrocarbons which are gaseous at room temperature and have 4 or fewer carbon atoms in the molecule may be prepared separately by prior mixing 5 of these components, for example in an autoclave under pressure.
Thi~ mixture iB then preferably added to the polyol component in a conventional manner. It is also possible to meter the hydrocarbon components individually into the material stream, preferably into the polyol component, immediately before it is 10 passed to the mixing head for the mixing of polyol component and isocyanate component. Metering into a specific multicomponent mixing head is also possible. The handling of the hydrocarbons with pumps, metering apparatus and storage vessels is carried out in a known manner.
The flame-retardant, isocyanate-based rigid foams according to the invention are produced by reacting, in a manner known per se, 20 a) organic and/or modified organic polyisocyanates with b) at least one higher-molecular-weight compound having at least two reactive hydrogen atoms and, if desired 25 c) low-molecular-weight chain extenders and/or crosslinkers in the presence of 30 d) flame retardants, e) water, f) the novel blowing agent mixture and g) other auxiliaries and/or additives.
These isocyanate-based rigid foams are especially those which contain urethane groups and/or isocyanurate groups and/or biuret 40 groups and/or allophanate groups and/or uretdione groups and/or urea groups and/or carbodiimide groups as characteristic chemical structural elements.
BASF Aktiengesellschaft 960200 O.Z. 0050/47828 With the exception of the blowing agents (d), the constituents used for producing the isocyanate-based rigid foams in the novel process are known per se, and are individually described below.
5 a) Suitable organic polyisocyanates are the aliphatic, cycloaliphatic, araliphatic and preferably aromatic polyfunctional isocyanates known per se.
Specific examples are: alkylene diisocyanates having from 4 to 12 carbon atoms in the alkylene radical, such as dodecane 1,12-diisocyanate, 2-ethyltetramethylene 1,4-diisocyanate, 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 any desired mixtures of these isomers, l-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate), 2,4- and 2,6-hexahydrotolylene diisocyanate and the corresponding isomer mixtures, dicyclohexylmethane 4,4'-, 2,2'- and 2,4'-diisocyanate and the corresponding isomer mixtures, and preferably aromatic di- 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 4,4'- and 2,4'-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 di- and polyisocyanates can be used individually or in the form of their mixtures.
Use is also frequently made of modified polyfunctional isocyanates, ie. products obtained by chemical reaction of organic di- and/or polyisocyanates. Examples are di- and/or polyisocyanates containing ester groups, urea groups, biuret groups, allophanate groups, carbodiimide groups, isocyanurate groups, uretdione groups and/or urethane groups. Specific examples are: organic, preferably aromatic, polyisocyanates containing urethane 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, for example with low-molecular-weight diols, triols, dialkylene glycols, trialkylene glycols or polyoxyalkylene glycols having molecular weightR of up to 6000, in particular having molecular weights up to 1500, modified diphenylmethane BASF Aktiengesellschaft 960200 O.Z. 0050/47828 4,4'-diisocyanate, modified diphenylmethane 4,4'- and 2,4~-diisocyanate mixtures, modified raw MDI or tolylene 2,4-and~or 2,6-diisocyanate, examples of dialkylene or polyoxyalkylene glycols, which may be used individually or as mixtures, are: diethylene, dipropylene, polyoxyethylene, polyoxypropylene and polyoxypropylene-polyoxyethylene glycols, and the corresponding triols and/or tetrols. Other suitable compounds are prepolymers containing 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 polyester polyols and/or preferably polyether polyols described below 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. Liquid polyisocyanates 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, for example those based on diphenylmethane 4,4'-, 2,4'- and/or 2,2'-diisocyanate and~or tolylene 2,4- and~or 2,6-diisocyanate have also proven useful.
The modified polyisocyanates may, if desired, be mixed with one another or with unmodified organic polyisocyanates, such as diphenylmethane 2,4'- or 4,4'-diisocyanate, raw MDI, tolylene 2,4- and/or 2,6-diisocyanate.
Organic polyisocyanates which have proven especially useful are diphenylmethane diisocyanate isomer mixtures or raw MDI
having a diphenylmethane diisocyanate isomer content of from 33 to 55% by weight, and polyisocyanate mixtures containing urethane groups and based on diphenylmethane diisocyanate having an NCO content of from 15 to 33% by weight.
b) Higher-molecular-weight compounds (b) having at least two reactive hydrogen atoms are expediently those having a functionality of from 2 to 8, preferably from 2 to 6, and a molecular weight of from 300 to 8000, preferably from 300 to 3000. Examples of compounds which have proven useful are polyether polyamines and/or preferably polyols selected from the class consisting of polyether polyols, polyester polyols, polythioether polyols, polyesteramides, hydroxyl-containing polyacetals, hydroxyl-containing aliphatic polycarbonates and mixtures of at least two of the polyols mentioned. Preference is given to the use of polyester polyols and/or polyether polyols. The hydroxyl number of the polyhydroxy compounds BASF Aktiengesellschaft 960200 O.Z. 0050/47828 here is generally from 150 to 850 mg KOH/g and preferably from 200 to 600 mg KOH/g.
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 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 here may also be used either in mixtures with one another or individually. The corresponding dicarboxylic acid derivatives, such as dicarboxylic esters of alcohols having from 1 to 4 carbon atoms or dicarboxylic anhydrides may also be used instead of the free dicarboxylic acids. Preference is given to the use of dicarboxylic acid mixtures of succinic, glutaric and adipic acid in a mixing ratio of, for example, from 20 to 35 : from 35 to 50 : from 20 to 32 parts by weight, and in particular adipic acid.
Examples of di- and polyhydric alcohols, in particular diols, are: ethanediol, diethylene glycol, 1,2- and 1,3-propanediol, dipropylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,10-decanediol, 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 diols mentioned, in particular mixtures of 1,4-butanediol, 1,5-pentanediol and 1,6-hexanediol. Polyester polyols, derived from lactones, such as ~-caprolactone, or hydroxycarboxylic acids, such as ~-hydroxycaproic acid, may also be used.
To prepare the polyester polyols, the organic, for example aromatic, and preferably aliphatic, polycarboxylic acids andlor their derivatives and polyhydric alcohols may be polycondensed without catalysts or preferably in the presence of esterification catalysts, expediently in an atmosphere of inert gas, such as nitrogen, carbon monoxide, helium, argon etc., in melt form at from 150 to 250~C, preferably from 180 to 220~C, under reduced pressure if desired, to the desired acid number of advantageously less than 10, preferably less than 2. In a preferred embodiment, the esterification mixture is polycondensed at the abovementioned temperatures to an acid number of from 80 to 30, preferably from 40 to 30, at atmospheric pressure and then under a pressure of less than BASF Aktiengesellschaft 960200 O.Z. 0050/47828 500 mbar, preferably from 50 to 150 mbar. Examples of suitable esterification catalysts are iron, cadmium, cobalt, lead, zinc, antimony, maqnesium, titanium and tin, in the form of metals, metal oxides or metal salts. The polycondensation may, however, also be carried out in liquid phase in the presence of diluents and/or entrainers, such as benzene, toluene, xylene or chlorobenzene, for removal of the water of condensation by azeotropic distillation.
To prepare the polyester polyols, the organic polycarboxylic acids and/or their derivatives and polyhydric alcohols are polycondensed advantageously in a molar ratio of 1: from 1 to 1.8, preferably 1: from 1.05 to 1.2.
The resultant polyester polyols preferably have a functionality of 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 used in particular are polyether polyols prepared by known processes from one or more alkylene oxides having from 2 to 4 carbon atoms in the alkylene radical for example by anionic polymerization using alkali metal hydroxides, such as sodium hydroxide or potassium hydroxide, or alkali metal alkoxides, such as sodium methoxide, sodium ethoxide, potassium ethoxide or potassium isopropoxide as catalysts and with addition of at least one initiator molecule having from 2 to 8, preferably from 2 to 6, reactive hydrogen atoms in its structure, or by cationic polymerization using Lewis acids, such as antimony pentachloride, boron fluoride etherate, etc., or bleaching earth as catalysts.
Examples of suitable alkylene oxides are tetrahydrofuran, 1,3-propylene oxide, 1,2- and 2,3-butylene oxide, styrene oxide and preferably ethylene oxide and 1,2-propylene oxide.
The alkylene oxides may be used individually, alternating in sequence or as mixtures. Examples of initiator molecules are:
water, organic dicarboxylic acids, such as succinic acid, adipic acid, phthalic acid and terephthalic acid, aliphatic and aromatic diamines, which may be unsubstituted or have N-mono-, N,N- or N,N~-dialkyl substitution, having from 1 to 4 carbon atoms in the alkyl radical, such as unsubstituted or mono- or dialkyl-substituted ethylenediamine, diethylenetriamine, triethylenetetramine, 1,3-propylenediamine, 1,3- or 1,4-butylenediamine, 1,2-, BASF Aktienge~ell~chaft 960200 O.Z. 0050~47828 1,3-, 1,4-, 1,5- or 1,6-hexamethylenediamine, phenylenediamine, 2,3-, 2,4- or 2,6-tolylenediamine, 4,4~-, 2,4~- or 2,2'-diaminodiphenylmethane.
Other initiator molecules which are suitable are:
alkanolamines, such as ethanolamine and N-methyl- and N-ethylethanolamine, dialkanolamines, such as diethanolamine and N-methyl- and N-ethyldiethanolamine, and trialkanolamines, such as triethanolamine, and ammonia.
Preference is given to the use of polyhydric, in particular di- and/or trihydric alcohols, such as ethanediol, 1,2-propanediol, 1,3-propanediol, diethylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, glycerol, trimethylolpropane, pentaerythritol, sorbitol and sucrose.
The polyether polyols, preferably polyoxypropylene polyols and polyoxypropylene-polyoxyethylene polyols, have a functionality of preferably from 2 to 6 and in particular from 2 to 4, and molecular weights of from 300 to 3000, preferably from 300 to 2000, and in particular from 400 to 2000, and suitable 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 and 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, expediently in the abovementioned polyether polyols, using as a basis the information 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 polyether polyol dispersions which contain, for example, as disperse phase, usually in an amount of from 1 to 50% by weight, preferably from 2 to 25%
by weight, examples being polyureas, polyhydrazides, melamine and/or polyurethanes containing bonded tertiary amino groups, and which are described, for example, in EP-B-011 752 (US 4 304 708), US-A-4 374 209 and DE-A-32 31 497.
The polyether polyols may, like the polyester polyols, be used individually or in the form of mixtures. They may also be mixed with the graft polyether polyols or polyester BASF Aktiengesellschaft 960200 O.Z. 0050/47828 polyols and with the hydroxyl-containing polyester amides, polyacetals, polycarbonates and/or polyether polyamines.
Examples of hydroxyl-containing polyacetals are the compounds which can be prepared from glycols, such as diethylene glycol, triethylene glycol, 4,4'-dihydroxyethoxy-diphenyldimethylmethane or hexanediol and formaldehyde.Suitable polyacetals may also be prepared by polymerizing cyclic acetals.
Suitable hydroxyl-containing polycarbonates are those of the 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, such as diphenyl carbonate, or phosgene.
Examples of polyester amides are the pre~ in~ntly linear condensates which are obtained from polybasic, saturated and/or unsaturated carboxylic acids and/or their anhydrides and polyhydric saturated and/or unsaturated aminoalcohols or mixtures of polyhydric alcohols and aminoalcohols and/or polyamines.
Suitable polyether polyamines can be prepared from the abovementioned polyether polyols by known processes, for example the cyanoalkylation of polyoxyalkylene polyols followed by hydrogenation of the resultant nitrile (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).
c) The isocyanate-based rigid foams may be produced with or without the additional use of chain extendPrs and/or crosslinkers. The addition of chain extenders, crosslinkers or else, if desired, mixtures of these can prove advantageous, however, for modifying the mechanical properties, for example the rigidity. Chain extenders and/or crosslinkers which are used are diols and/or triols having molecular weights of less than 400, preferably from 60 to 300. Examples of these are aliphatic, cycloaliphatic and/or araliphatic diols having from 2 to 14, preferably from 4 to 10, carbon atoms, such as ethylene glycol, 1,3-propanediol, l,10-decanediol, o-, m- and p-dihydroxycyclohexane, diethylene glycol, dipropylene glycol and preferably 1,4-butanediol, 1,6-hexanediol and bis(2-hydroxyethyl)-CA 02228969 1998-03-lo BASF Aktienge~ellschaft 960200 O.Z. 0050/47828 hydroquinone, triols, such as 1,2,4- and 1,3,5-trihydroxycyclohexane, glycerol and trimethylolpropane, and low-molecular-weight hydroxyl-containing polyalkylene oxides based on ethylene oxide and/or 1,2-propylene oxide and the abovementioned diols and/or triols as initiator molecules.
If chain extenders, crosslinkers or mixtures of these are used for producing the isocyanate-based rigid foams, these are expediently used in an amount of from 0 to 20% by weight, preferably from 2 to 8% by weight, based on the weight of component (b).
15 d) The isocyanate-based rigid foams according to the invention are flame-retardant. The flame retardants used may be any of the usual materials used for this purpose in polyurethane chemistry. Halogen compounds and phosphorus compounds are predominantly used.
Examples of suitable flame retardants are tricresyl phosphate, tris~2-chloroethyl) phosphate, tris(2-chloropropyl) phosphate, tris(1,3-dichloropropyl) phosphate, tris(2,3-dibromopropyl) phosphate, tetrakis(2-chloroethyl) ethylene diphosphate, dimethyl methanephosphonate, diethyl diethanolaminomethylphosphonate and commercially available halogen-containing flame-retardant polyols.
Since the isocyanate-based rigid foam of the future should be produced only using halogen-free additives, the flame retardants should also be halogen-free. Examples of these are derivatives of phosphoric acid, phosphorous acid or phosphonic acid and which are reactive to isocyanate; these may, if desired, be combined with non-reactive liquid and/or solid halogen-free flame retardants, eg. those made from organic derivatives of phosphoric acid, phosphonic acid or phosphorous acid and/or from salts of phosphoric acid.
Besides the abovementioned materials, use may also be made of inorganic or organic flame retardants such as red phosphorus, alumina hydrate, antimony trioxide, arsenic oxide, ammonium polyphosphate and calcium sulfate, expandable graphite or cyanuric acid derivativqs, such as melamine, or mixtures of at least two flame retardants, such as ammonium BASF Aktiengesell~chaft 960200 O.Z. 0050/47828 polyphosphates and melamine and, if desired, maize starch or ammonium polyphosphate, melamine and expandable graphite.
Particular preference is given to tris(2-chloropropyl) phosphate, phosphonic acid derivatives, ammonium polyphosphate and expandable graphite.
The use of the novel halogen-free blowing agent mixture (f) of liquid and gaseous hydrocarbons avoids the use of unnecessarily large amounts of hydrocarbon and thus makes an indirect contribution to flame retardancy. It has generally proven expedient to use from 5 to 50 parts by weight, preferably from 5 to 25 parts by weight, of the abovementioned flame retardants for each 100 parts by weight of component (b).
e) Water is used as chemical blowing agent and reacts with isocyanate groups of component (a) with formation of carbon dioxide. The water is preferably added to component (b) in an amount of from 0.5 to 5% by weight, based on the weight of component (b). The addition of water may be combined with the use of the blowing agents to be used according to the invention.
f) For producing the isocyanate-based, flame-retardant rigid foams use is made, according to the invention, as described above, of a blowing agent mixture consisting of a mixture of at least one non-cyclic hydrocarbon which is liquid at room temperature and has 5 or more carbon atoms in the molecule and at least one hydrocarbon which is gaseous at room temperature and has 4 or fewer carbon atoms in the molecule.
As likewise described above, the novel blowing agent mixture is advantageously introduced into the polyol component consisting of the formative components (b), (d), (e), the catalysts (g) and, if desired, (c) and other auxiliaries and/or additives (g), or the hydrocarbons are metered in individually.
40 g) For producing the flame-retardant rigid foams, use is usually made of catalysts and, if desired, other auxiliaries and/or additives.
Compounds used as catalysts (g) are in particular those which bring about a pronounced acceleration of the reaction of the compounds of component (b) which contain reactive hydrogen atoms, in particular hydroxyl groups, and (c) if used, with BASF Aktiengesellschaft 960200 O.Z. 0050/47828 the organic, unmodified or modified polyisocyanates (a). By means of suitable catalysts (g), the isocyanate groups may, however, also be induced to react with one another, giving preferably isocyanurate structures, besides the adducts between isocyanates (a) and the compounds (b) having groups with active hydrogen.
The catalysts used are therefore in particular those which accelerate reactions of the isocyanates, especially urethane, urea and isocyanurate formation.
Preferred compounds for this purpose are tertiary amines, tin compounds, bismuth compounds, alkali metal carboxylates, alkaline-earth metal carboxylates, quaternary ammonium salts, s-hexahydrotriazines and tris(dialkylA inf ?thyl)phenols.
Examples of suitable catalysts are organometallic compounds, preferably organotin compounds, such as tin(II) salts of organic carboxylic acids, e.g. tin(II) acetate, tin~II) octoate, tin(II) ethylhexoate and tin(II) laurate, and the dialkyltin(IV) salts of organic carboxylic acids, such as dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate and dioctyltin diacetate. The organometallic compounds are used alone or preferably in combination with strongly basic amines, for example amidines, such as 2,3-dimethyl-3,4,5,6-tetrahydropyrimidine, tertiary amines, such as triethylamine, tributylamine, dimethylbenzylamine, N-methyl-, N-ethyl- and N-cyclohexylmorpholine, N, N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetramethylbutanediamine, N, N~N~N~-tetramethyl-1~6-hexanediamine~
pentamethyldiethylenetriamine, tetramethyldiaminoethyl ether, bis(dimethylaminopropyl)urea, dimethylpiperazine, 1,2-dimethylimidazole, 1-azabicyclo[3.3.0]octane and preferably 1,4-diazabicyclo[2.2.2~octane, and alkanolamine compounds, 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, 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 alkali metal salts of long-chain fatty acids having from 10 to 20 carbon atoms and with or BASF Aktiengesellschaft 960200 O.Z. 0050/47828 without OH side groups. It is preferable to use 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 component (b).
Further auxiliaries and/or additives (g) may, if desired, also be incorporated into the reaction mixture for producing the isocyanate-based rigid foams according to the invention in addition to the catalysts. Examples of these are surfactants, foam stabilizers, cell regulators, fillers, dyes, pigments, agents to protect against hydrolysis and substances with fungistatic and bacteriostatic action.
Examples of suitable surfactants are compounds which serve to promote the homogenization of the starting materials and, if desired, are also suitable for regulating the cell structure of the plastics. Examples of these are emulsifiers, such as the sodium salts of castor oil sulfates, or of fatty acids, and salts of fatty acids with amines, such as diethylamine oleate, diethanolamine stearate, diethanolamine ricinoleate, salts of sulfonic acids, such as alkali metal or ammonium salts of dodecylbenzene- or dinaphthylmethanedisulfonic acid and ricinoleic acid; foam stabilizers, such as siloxane-oxalkylene copolymers and other organopolysiloxanes, oxethylated alkyl phenols, oxethylated fatty alcohols, paraffin oils, castor oil esters, ricinoleic acid esters, Turkey red oil and groundnut oil, and cell regulators, such as paraffins, fatty alcohols and dimethylpolysiloxanes.
Suitable compounds for improving the emulsification action, the cell structure and/or stabilizing the foam are furthermore the oligomeric acrylates having polyoxyalkylene and fluoroalkane radicals as side groups as described above.
The surfactants are usually used in amounts from 0.01 to 5 parts by weight, based on 100 parts by weight of component (b)-The term fillers, in particular reinforcing fillers, is takento mean the usual organic and inorganic fillers, reinforcing agents, weighting agents, agents for improving the abrasion behavior in paints, coating agents, etc. which are known per se. Specific examples are: inorganic fillers, such as silicate minerals, for example phyllosilicates, such as antigorite, serpentine, hornblendes, 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, such as cadmium sulfide, zinc sulfide and glass, etc. Preference is given to the use of BASF Aktiengesellschaft 960200 O.Z. 0050/47828 kaolin (china clay), aluminum silicate and coprecipitates of barium sulfate and aluminum silicate, and natural and synthetic fibrous minerals, such as wollastonite, metal fibers and in particular glass fibers of various lengths, which may be provided with a size if desired. Examples of organic fillers are: starch, carbon, melamine, colophony, cyclopentadienyl resins, graft polymers, cellulose fibers, polyamide fibers, polyacrylonitrile fibers, polyurethane fibers, polyester fibers based on aromatic and/or aliphatic dicarboxylic acid esters, and in particular carbon fibers.
The inorganic and organic fillers may be used individually or as 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 components (a) to ~c), where, however, the content of mats, nonwovens and wovens made from natural and synthetic fibers may reach values of up to 80.
Further details concerning the abovementioned further starting materials may be found in the specialist literature, for example in the Monograph of H.J. Saunders and K.C. Frisch, High Polymers, Vol. XVI, Polyurethanes, Parts 1 and 2, Interscience Publishers 25 1962 and 1964, or the Kunststoffhandbuch as mentioned above, Polyurethane, Vol. VII, Carl Hanser Verlag, Munich, Vienna, 1st, 2nd and 3rd editions, 1966, 1983 and 1993.
For producing the isocyanate-based rigid foams, the organic 30 and/or modified organic polyisocyanates ~a), higher-molecular-weight compounds having at least two reactive hydrogen atoms (b) and, if desired, chain extenders and/or crosslinkers (c) are reacted in amounts giving an equivalents ratio of NC0 groups in the polyisocyanates (a) to the total of 35 the reactive hydrogen atoms in components (b) and, if used, (c) of 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 isocyanate-based rigid foams contain, at least to some extent, isocyanurate groups in their structures, the ratio of NC0 groups in the polyisocyanates ~a) to 40 the total of the reactive hydrogen atoms in component (b) and, if used, (c) is usually from 1.5 to 60:1, preferably from 3 to 8:1.
The isocyanate-based rigid foams according to the invention are preferably produced by the casting or spraying process, using in 45 particular block foaming or mold foaming or continuous production in the double belt conveyor process. It is advantageous to operate with the one-shot process, for example using the BASF Aktienge8ellschaft 960200 O.Z. 0050/47828 high-pressure or low-pressure technique, in open or closed molds.
It has proven especially advantageous to operate with the two-component process and to combine the formative components (b), ~d), (e), (f) and catalysts (g) and, if used, (c) and other 5 auxiliaries and/or additives (g) in the component (A) and to use the organic polyisocyanates and/or modified polyisocyanates (a) or mixtures of these polyisocyanates and, if desired, blowing agent (f) as the component (B).
lO The starting components are mixed at from 15 to 90~C, preferably from 20 to 60~C, in particular from 20 to 35~C, and introduced into the open mold or, if desired, under elevated pressure into the closed mold. The mixing can, as already stated, be carried out mechanically using a spiral mixer or other agitator. The mold 15 temperature is expediently 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 poYsible to use more foam-forming 20 reaction mixture than is required for complete filling of the mold, this then gives compressed foams.
The rigid polyurethane foams or rigid molded foams produced by the novel process have a density of from 0.02 to 0.75 g/cm3, 25 preferably from 0.025 to 0.24 g~cm3, and in particular from 0.03 to 0.1 g/cm3.
The products are preferably used as thermally insulating building materials.
The invention will be described in greater detail using the following working examples:
35 Working Examples 1 - 4 and Comparative Examples 1 - 2:
The following polyol blend (polyol) was prepared for the formulations given in Table 1 for the examples and comparative examples:
Polyetheralcohol based on48 parts by weight sorbitol/propylene oxide, hydroxyl number 355 mg KOH/g, Polyethylene glycol,5 parts by weight BASF Aktienge~ell~chaft 960200 O.Z. 0050/47828 Hydroxyl number 190 mg KOH~g, Castor oil, 15 parts by weight Hydroxyl number 165 mg KOH/g, Trischloropropyl phosphate, 20 parts by weight Diphenyl cresyl phosphate, 10 parts by weight Organosilicon-based foam 2 parts by weight stabilizer (DABCO DC 193, Air Products), 15 The following physical blowing agents were used for the examples and comparative examples;
Blowing agent 1 (according to the invention):
n-Pentane 68 parts by weight Isopentane7 parts by weight n-Butane 10 parts by weight Isobutane 5 parts by weight Blowing agent 2 (according to the invention):
Cyclopentane 72 parts by weight n-Butane 28 parts by weight Blowing agent 3 (according to the invention):
n-Pentane70 parts by weight Isopentane8 parts by weight n-Butane 7 parts by weight Isobutane4 parts by weight Propane 1 part by weight Blowing agent 4 (comparative):
n-Pentane 80 parts by weight Isopentane20 parts by weight BASF Aktienge~ellschaft 960200 O.Z. 0050/47828 Blowing agent 5 (comparative);
Cyclopentane 100 parts by weight.
To produce the rigid polyurethane polyisocyanurate foams, in each case a charge of 500 g of the formulations shown in Table 1 was prepared in a mixing vessel and 480 g of this material were transferred into a lidded foam mold of dimensions 210 x 210 x 200 mm, an overall density of the foam of about 55 g/dm3 being achieved at a compaction of about lO percent. After a hardening time of one hour, the foam was removed from the mold and the fire performance was determined according to DIN 4102 24 hours after production.
The results of the fire test are given in the lower part of the table and show the improved fire performance obtained on using the novel blowing agents.
20 The blowing effect of the novel blowing agent mixtures is better than that obtained from the sole use of hydrocarbons which are liquid at room temperature.
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Claims (14)
1. A process for producing flame-retardant, isocyanate-based rigid foams by reacting a) organic and/or modified organic polyisocyanates with b) at least one higher-molecular-weight compound having at least two reactive hydrogen atoms and, if desired c) low-molecular-weight chain extenders and/or crosslinkers in the presence of d) flame retardants, e) water, f) blowing agents and g) other auxiliaries and/or additives, which comprises using, as blowing agents, a mixture of at least one hydrocarbon which is liquid at room temperature and has 5 or more carbon atoms in the molecule with at least one hydrocarbon which is gaseous at room temperature and has 4 or fewer carbon atoms in the molecule.
2. A process as claimed in claim 1, wherein the hydrocarbons which are liquid at room temperature and have 5 or more carbon atoms in the molecule are used in an amount of from 0.1 to 10% by weight, based on the total amount of the foam.
3. A process as claimed in claim 1, wherein the hydrocarbons which are gaseous at room temperature and have 4 or fewer carbon atoms in the molecule are used in an amount of from 0.1 to 10% by weight, based on the total amount of the foam.
4. A process as claimed in claim 1, wherein the hydrocarbons which are liquid at room temperature and have 5 or more carbon atoms in the molecule are cyclopentane, cyclohexane and/or methylcyclohexane.
5. A process as claimed in claim 1, wherein the hydrocarbons which are liquid at room temperature and have 5 or more carbon atoms in the molecule are non-cyclic hydrocarbons.
6. A process as claimed in claim 5, wherein the non-cyclic hydrocarbons which are liquid at room temperature and have 5 or more carbon atoms in the molecule are n-pentane and/or isopentane.
7. A process as claimed in claim 5, wherein the non-cyclic hydrocarbons which are liquid at room temperature and have 5 or more carbon atoms in the molecule are n-hexane and/or its isomers.
8. A process as claimed in claim 1, wherein the hydrocarbons which are liquid at room temperature and have 5 or more carbon atoms in the molecule are alkenes.
9. A process as claimed in claim 1, wherein the hydrocarbons which are liquid at room temperature and have 5 or more carbon atoms in the molecule are hexenes and/or their isomers.
10. A process as claimed in claim 1, wherein the hydrocarbons which are gaseous at room temperature and have 4 or fewer carbon atoms in the molecule have 3 or 4 carbon atoms.
11. A process as claimed in claim 1, wherein the hydrocarbon which is gaseous at room temperature and has 4 or fewer carbon atoms in the molecule is n-butane.
12. A process as claimed in claim 1, wherein the hydrocarbon which is gaseous at room temperature and has 4 or fewer carbon atoms in the molecule is isobutane.
13. A blowing agent mixture for producing isocyanate-based, flame-retardant rigid foams as claimed in claim 1, consisting of a mixture of at least one hydrocarbon which is liquid at room temperature and has 5 or more carbon atoms in the molecule with at least one hydrocarbon which is gaseous at room temperature and has 4 or fewer carbon atoms in the molecule, in association with the carbon dioxide produced from water and isocyanate.
14. The use of an isocyanate-based, flame-retardant rigid foam produced as claimed in claim 1 as insulation material in the building sector.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19709867.3 | 1997-03-11 | ||
| DE19709867A DE19709867A1 (en) | 1997-03-11 | 1997-03-11 | Process for the production of flame retardant rigid foams based on isocyanate |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2228969A1 true CA2228969A1 (en) | 1998-09-11 |
Family
ID=7822894
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002228969A Abandoned CA2228969A1 (en) | 1997-03-11 | 1998-03-10 | Production of flame-retardant, isocyanate-based rigid foams |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP0864601A1 (en) |
| CA (1) | CA2228969A1 (en) |
| DE (1) | DE19709867A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE10337787A1 (en) * | 2003-08-14 | 2005-03-24 | Basf Ag | Flame retardant rigid polyurethane foam containing silicone-free foam stabilizers |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3933335C2 (en) * | 1989-10-06 | 1998-08-06 | Basf Ag | Process for the production of rigid polyurethane foams with low thermal conductivity and their use |
| CA2141735C (en) * | 1992-08-04 | 2004-07-06 | Wilhelm Lamberts | Process for the production of hard polyurethane foams |
| DE4446847A1 (en) * | 1994-12-27 | 1996-07-04 | Basf Schwarzheide Gmbh | Process for the production of flame retardant rigid foams based on isocyanate |
-
1997
- 1997-03-11 DE DE19709867A patent/DE19709867A1/en not_active Withdrawn
-
1998
- 1998-03-02 EP EP98103627A patent/EP0864601A1/en not_active Withdrawn
- 1998-03-10 CA CA002228969A patent/CA2228969A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| EP0864601A1 (en) | 1998-09-16 |
| DE19709867A1 (en) | 1998-09-17 |
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