DE19519679A1 - Rigid polyurethane foam prodn. with reduced after-expansion and cracking - Google Patents

Abstract

Prepn. of rigid polyurethane foam with reduced after-expansion and decreased mould release times comprises reacting (a) organic and/or modified organic polyisocyanates with (b) high molecular cpd(s). contg. at least 2 reactive H atoms and opt. (c) low molecular chain extender and/or crosslinker in the presence of (d) blowing agent, (e) catalyst, (f) alkali metal salt (I) and opt. (g) other ancillaries and/or additives. (I) is dialkali H phosphate (IA) with an alkali content of 50-2500 ppm w.r.t. the amt. of components (b)-(g). Also claimed is the obtd. foam.

Description

The invention relates to a process for the preparation of polyure than rigid foams with reduced drag and shorter Demoulding times by implementing

• a) organic and / or modified organic polyiso cyanates with
• b) at least one higher molecular compound with at least two reactive hydrogen atoms and optionally
• c) low molecular chain extension and / or crosslinking average in the presence of
• d) blowing agents,
• e) catalysts
• f) alkali metal salts and optionally
• g) other auxiliaries and / or additives.

The production of rigid polyurethane foams by implementation of organic polyisocyanates and / or modified organi polyisocyanates with higher functional compounds at least two reactive hydrogen atoms, for example poly oxyalkylene polyamines and / or preferably organic poly hydroxyl compounds, especially polyetherols with molecular weight weight from z. B. 300 to 2000, and optionally chains extenders and / or crosslinking agents with molecular weights up to approx. 400 in the presence of catalysts, blowing agents, auxiliaries means and / or additives is known and has been widely wrote. A summary overview of the manufacturing of rigid polyurethane foams z. B. in the plastic hand book, Volume VII, "Polyurethane", 1st edition 1966, published from Dr. R. Vieweg and Dr. A. Höchtlen, and 2nd edition, 1983 issued by Dr. G. Oertel (Carl Hanser Verlag, Munich), opp ben.

As polyol components for rigid polyurethane foam systems, usually highly functional short-chain polyether alcohols with a correspondingly high hydroxyl number used. The manufacture of the like products are usually done by anionic polymerization lower alkylene oxides, mostly 1,2-propylene oxide, if appropriate in a mixture with ethylene oxide or butylene oxide, at high, too usually at least four-functional connections with active Hydrogen atoms. Common starting substances are next to it Amines in particular hydroxyl-containing compounds such as. B.  Pentaerythritol, sorbitol, mannitol, xylitol, glucose or sucrose. Sorbitol and sucrose are particularly preferred.

To improve the technological process of alkylene oxide accumulation are usually liquid co-starters, usually with significantly less functionality, such as. B. Diethylene glycol, ethylene glycol and glycerin.

The Ka used as a catalyst for the alkylene oxide addition lium hydroxide is after the completion of the after-reaction phase after a appropriate neutralization with acids by filtration of the ge formed salts, if necessary with the addition of filtration aids removed to a residual alkali content of <50 ppm potassium.

Additions of potassium salts have been found in the literature knows. This is particularly true for those foams where consciously to be formed polyisocyanurate structures, and at Foams, in which you can increase the who wants to avoid the disadvantageous swelling. So ins special additions of potassium octoate in CA-A 20 46 235 called. The foams according to the invention have an isocyanate index from 110-300.

According to JP-A 4018448, sodium or potassium salts of carbon are used acids as a catalyst, in particular potassium salts of the vinegar acid, propionic acid, fumaric acid and adipic acid can be called.

According to EP-A 47260, alkali metal salts of carboxylic acids are used partly used in flexible foams.

An open-celled rigid polyurethane foam by using u. a. from Alkali metal salts of maleic acid are described in JP-A 2020534 speaks.

The Chinese patent CN-A 1041371 describes rigid foams described, which using alkali metal salts of Po lyhydroxyphosphates and carboxylic acids.

Open-cell rigid foams are disclosed in JP-A 63116082 u. a. by With the use of potassium acetate generated, evacuable hard foams should arise.

The use of is also used for flame retardant rigid foams Potassium acetate (GB 1540663) is sufficiently described.  

According to BE-A 818834, amine catalysts are used in combination with Alkali metal salts such as chlorides, bromides, nitrates, sulfates and thiosulfates used for cold-curing foams.

According to US-A 3 413 245 and WO 9013587 alkali metal salts of Carboxylic acids used.

All of the writings mentioned convey the teaching through the addition of alkali metal salts increases the dimensional stability of the foams improve. In practice, potassium acetate and Ka lium octoate recommended as the suitable alkali metal salts.

DE-A 43 15 874 describes a process for the preparation of polyure than foams, preferably polyurethane semi-rigid foams, described, in which a Ver wetting agent is used, which consists of at least one poly oxyalkylene polyol with an average functionality of 3 to 8 and a hydroxyl number of 200 to 1300 mg KOH / g and has an alkali ion content of 150 to 1200 ppm.

For this purpose, the polyoxyalkylene polyols are mixed with aqueous alkali hydroxide, preferably an aqueous potassium hydroxide solution, or alcoholic alkali alcoholate solutions, preferably alcoholic Potassium alcoholate solutions treated.

The present invention was based on the object of polyurethane to show rigid foams that have a reduced downforce and have less cracking and therefore earlier Allow demolding without the other properties of the Foams will deteriorate.

This object is achieved in that Dialkali hydrogen phosphate, optionally in combination with others Alkali metal salts is used.

The invention accordingly relates to a method for the manufacture position of rigid polyurethane foams with reduced Caster and shorter demolding times by implementing

• a) organic and / or modified organic polyiso cyanates with
• b) at least one higher molecular compound with at least two reactive hydrogen atoms and optionally
• c) low molecular chain extension and / or crosslinking average

in the presence of

• d) blowing agents,
• e) catalysts
• f) alkali metal salts and optionally
• g) further auxiliaries and / or additives,

characterized in that as alkali metal salt dialkalihydro gene phosphate with an alkali content of 50 to 2500 ppm, based on the amount of components b) to g) is used.

The invention further relates to rigid polyurethane foam fabrics with reduced caster and shorter demolding times, containing at least one alkali metal salt and optionally other aids and / or additives known per se, since characterized in that as alkali metal salt dialkali hydrogen phosphate with an alkali content of 50 to 2500 ppm, based on the amount of components b) to g) is included, and the Use of these rigid polyurethane foams as insulation materials rial in the construction and refrigeration sector.

It was surprising and unpredictable that if to foam production in the presence of dialkalihydro gene phosphate, especially dipotassium hydrogen phosphate, or Kombina ions of dialkali hydrogen phosphate with other alkali salts, especially potassium acetate, in the amounts according to the invention leads to a significant influence on the downstream and demoulding behavior of rigid polyurethane foams compared to foams, which have no or not the alkali salts according to the invention, occurs, with other important foam physical data such as Dimensional stability and compressive strength through the addition of Potassium salts according to the invention are not adversely affected. This significantly reduces the demolding times. It thus became an economical process for the production of Rigid polyurethane foams that are excellent as Isolati suitable material found.

For the use of Dialkalihydrogenphos according to the invention Phaten, possibly in combination with other alkali salts, are suitable in principle all known rigid polyurethane foams, which can be produced according to the usual methods nen.  

For the production of rigid polyurethane foams after Find methods according to the invention, with the exception of the special Alkali metal salts (f), the structural components known per se Use for which the following must be carried out in detail.

a) As an organic and / or modified organic polyiso cyanates (a) are the aliphatic, known per se, cycloaliphatic, araliphatic and preferably the aro Matic polyvalent isocyanates in question.

Examples include: alkylene diisocyanates with 4 to 12 carbon atoms in the alkylene radical, such as 1,12-dode candiioscyanate, 2-ethyl-tetramethylene diisocyanate-1,4,2-Me thylpentamethylene diisocyanate-1,5, tetramethylene diiso cyanate 1,4, and preferably hexamethylene diisocyanate 1,6; cycloaliphatic diisocyanates such as cyclohexane-1,3- and 1,4-diisocyanate and any mixtures of these isomers, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI), 2,4- and 2,6-hexahydrotoluenediisocyanate and the corresponding mixtures of isomers, 4,4'-, 2,2'- and 2,4'-di cyclohexylmethane diisocyanate and the corresponding iso mixed mixtures, and preferably aromatic di- and polyiso cyanates such as B. 2,4- and 2,6-tolylene diisocyanate and corresponding mixtures of isomers, 4,4'-, 2,4'- and 2,2'-di phenylmethane diisocyanate and the corresponding isomers mixtures, mixtures of 4,4'- and 2,2'-diphenylmethane diiso cyanates, polyphenylpolymethylene polyisocyanates, mixtures from 2,4'-, 2,4'- and 2,2'-diphenylmethane diisocyanates and Po lyphenylpolymethylene polyisocyanates (raw MDI) and mixtures from raw MDI and tolylene diisocyanates. The organic di and Polyisocyanates can be used individually or in the form of their Mixtures are used.

So-called modified polyvalent iso are also common cyanate, d. H. Products that are organi shear di- and / or polyisocyanates are used. Examples include ester, urea, biuret, Allophanate, carbodiimide, isocyanurate, uretdione and / or Di- and / or polyisocyanates containing urethane groups. in the For example, some are: urethane groups containing organic, preferably aromatic polyiso cyanates with NCO contents of 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, triplets, dialkyls glycols, trialkylene glycols or polyoxyalkylene glycols Molecular weights up to 6000, especially with molecular weight weight up to 1500, modified 4,4'-diphenylmethane diiso  cynate, modified 4,4'- and 2,4'-diphenylmethane diisocya natural mixtures, modified raw MDI or 2,4- or 2,6-tolylene diisocyanate, being di- or polyoxyalkylene glycols that can be used individually or as mixtures NEN, for example: diethylene, dipropylene glycol, polyoxyethylene, polyoxypropylene and polyoxypropy lenpolyoxyethene glycols, triols and / or tetrols. Suitable are also prepolymers containing NCO groups with an NCO content from 25 to 3.5% by weight, preferably from 21 to 14% by weight, based on the total weight, made from the following described polyester and / or preferably poly ether polyols and 4,4'-diphenylmethane diisocyanate, mixtures from 2,4'- and 4,4'-diphenylmethane diisocyanate, 2,4- and / or 2,6-tolylene diisocyanates or crude MDI. Have proven themselves also liquid, carbodiimide groups and / or isocyanurate polyisocyanates containing rings with NCO contents of 33.6 to 15, preferably 31 to 21 wt .-%, based on the Ge velvet weight, e.g. B. based on 4,4'-, 2,4'- and / or 2,2'-diphenylmethane diisocyanate and / or 2,4- and / or 2,6-tolylene diisocyanate.

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

Organic polyisocyanates have proven particularly useful and are therefore preferably used: mixtures of Toluene diisocyanates and raw MDI or mixtures of modifi graced, organic polyiso containing urethane groups cyanates with an NCO content of 33.6 to 15 wt .-%, ins special ones based on tolylene diisocyanates, 4,4'-diphenylmethane diisocyanate, diphenylmethane diisocyanate Isomer mixtures or crude MDI and in particular crude MDI with a diphenylmethane diisocyanate isomer content of 30 to 80% by weight, preferably from 30 to 60% by weight, in particular from 30 to 55% by weight.

b) As higher molecular weight compounds with at least two reak tive hydrogen atoms (b) are expediently such with a functionality of 2 to 8, preferably 2 to 6, and a molecular weight of 300 to 8000, preferably of 300 to 3000 used. Have proven themselves. B. Polyether polyamines and / or preferably polyols selected from the Group of polyether polyols, polyester polyols, polythioethers polyols, polyester amides, hydroxyl-containing polyacetals and hydroxyl-containing aliphatic polycarbonates or  Mixtures of at least two of the polyols mentioned. Before polyester polyols and / or poly are preferably used ether polyols. The hydroxyl number of the polyhydroxyl compounds is usually 150 to 850 mg KOH / g and above preferably 200 to 600 mg KOH / g.

Suitable polyester polyols can, for example, from organic Dicarboxylic acids with 2 to 12 carbon atoms, preferred wise aliphatic dicarboxylic acids with 4 to 6 carbon a toms, and polyhydric alcohols, preferably diols, with 2 up to 12 carbon atoms, preferably 2 to 6 carbon atoms toms are produced. As dicarboxylic acids come in Examples include: succinic acid, glutaric acid, adipine acid, suberic acid, azelaic acid, sebacic acid, decanedicarbonate acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid and terephthalic acid. The dicarboxylic acids can both used individually as well as in a mixture with each other.

Instead of the free dicarboxylic acids, the corresponding ones can also be used Chenden dicarboxylic acid derivatives, such as. B. dicarboxylic acid esters of alcohols with 1 to 4 carbon atoms or dicarboxylic acid reanhydrides are used. Preferably used Dicarboxylic acid mixtures of succinic, glutaric and adipic acids in proportions of, for example, 20 to 35: 35 to 50: 20 to 32 parts by weight, and especially adipic acid. Examples of dihydric and polyhydric alcohols, in particular Diols are: ethanediol, diethylene glycol, 1,2- or 1,3-propane diol, dipropylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,10-decanediol, glycerin and trimethylolpro pan. Ethanediol, diethylene glycol are preferably used kol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol or Mi from at least two of the diols mentioned, in particular right mixtures of 1,4-butanediol, 1,5-pentanediol and 1,6-He xandiol. Polyester polyols can also be used from lactones, e.g. B. ε-caprolactone or hydroxycarboxylic acids, e.g. B. ω-hydroxycaproic acid.

To prepare the polyester polyols, the organic, e.g. B. aromatic and preferably aliphatic, polycarbonate acids and / or derivatives and polyhydric alcohols peat-free or preferably in the presence of esterification catalysts analyzers, suitably in an atmosphere of inert gas such as B. nitrogen, carbon monoxide, helium, argon and. a., in the melt at temperatures of 150 to 250 ° C, preferably as 180 to 220 ° C, optionally under reduced pressure up to the desired acid number, which is advantageous is less than 10, preferably less than 2, polycondenses be settled. According to a preferred embodiment, the  Esterification mixture at the above temperatures up to an acid number of 80 to 30, preferably 40 to 30, under Normal pressure and then under a pressure of less than 500 mbar, preferably 50 to 150 mbar, polycondensed. For example, iron, Cadmium, cobalt, lead, zinc, antimony, magnesium, titanium and Tin catalysts in the form of metals, metal oxides or Metal salts into consideration. However, the polycondensation can also in the liquid phase in the presence of dilution and / or Entraining agents such. As benzene, toluene, xylene or Chlorobenzene, for azeotropic distillation of the condensation water.

The organic polyols are used to produce the polyester polyols Polycarboxylic acids and / or derivatives and polyhydric alcohols advantageously in a molar ratio of 1: 1 to 1.8, preferably example 1: 1.05 to 1.2, polycondensed.

The polyester polyols obtained preferably have one Functionality from 2 to 4, especially 2 to 3, and a mo molecular weight from 480 to 3000, preferably 600 to 2000 and especially 600 to 1500.

However, polyethers are used in particular as polyols polyols by known methods, for example by anionic polymerization with alkali hydroxides, such as. B. Well trium or potassium hydroxide or alkali alcoholates, such as. B. Sodium methylate, sodium or potassium ethylate or potassium iso propylate, as catalysts and with the addition of at least one Starter molecule, the 2 to 8, preferably 2 to 6, reactive Contains hydrogen atoms bound, or by cationic Po lymerization with Lewis acids, such as antimony pentachloride, boron fluoride etherate u. a. or bleaching earth, as catalysts one or more alkylene oxides with 2 to 4 carbon atoms Men are produced in the alkylene radical.

Suitable alkylene oxides are, for example, tetrahydrofuran, 1,3-propylene oxide, 1,2- or 2,3-butylene oxide, styrene oxide and preferably ethylene oxide and 1,2-propylene oxide. The alkyleno xids can be used individually, alternately one after the other or as Mi be used. Come as starter molecules Examples include: water, organic dicarboxylic acids, such as succinic acid, adipic acid, phthalic acid and terephthalate acid, aliphatic and aromatic, optionally N-mono-, N, N- and N, N'-dialkyl-substituted diamines with 1 to 4 Koh lenstoffatomen in the alkyl radical, such as mono- and dialkyl-substituted ethylenediamine, diethylenetriamine, tri  ethylene tetramine, 1,3-propylene diamine, 1,3- or 1,4-butylene diamine, 1,2-, 1,3-, 1,4-, 1,5- and 1,6-hexamethylene diamine, Phenylenediamines, 2,3-, 2,4- and 2,6-toluenediamine and 4,4′-, 2,4'- and 2,2'-diamino-diphenylmethane.

Other suitable starter molecules are: alkanolamines, such as B. ethanolamine, N-methyl and N-ethylethanolamine, Dialkanolamines such as e.g. B. diethanolamine, N-methyl- and N-ethyl-diethanolamine, and trialkanolamines, such as. B. Triethano lamin, and ammonia. Mehrwerti are preferably used ge, especially di- and / or trihydric alcohols, such as Ethanediol, 1,2-propanediol and 1,3, diethylene glycol, dipropy lenglycol, 1,4-butanediol, 1,6-hexanediol, glycerin, trimethy lolpropane, pentaerythritol, sorbitol and sucrose.

The polyether polyols, preferably polyoxypropylene and poly oxypropylene-polyoxyethylene polyols, have a functional act from preferably 2 to 6 and in particular 2 to 4 and Mo. molecular weights of 300 to 3000, preferably 300 to 2000 and in particular 400 to 2000 and suitable polyoxytetra methylene glycols have a molecular weight of up to approximately 3500.

Polymer-modified are also suitable as polyether polyols Polyether polyols, preferably graft polyether polyols, in particular special ones based on styrene and / or acrylonitrile by in situ polymerization of acrylonitrile, styrene or preferably mixtures of styrene and acrylonitrile, e.g. B. in Weight ratio 90:10 to 10:90, preferably 70:30 to 30:70, advantageously in the aforementioned polyether polyols analogous to the information in German patent specifications 11 11,394, 12,22,669 (U.S. 3,304,273, 3,383,351, 3,523,093), 11 52 536 (GB 10 40 452) and 11 52 537 (GB 987 618) be, as well as polyether poly dispersions, which as disperse Phase, usually in an amount of 1 to 50% by weight preferably 2 to 25% by weight, contain: z. B. polyureas, Po lyhydrazide, tertiary amino groups containing bound polyure thane and / or melamine and the z. B. are described in the EP-B 011 752 (US 4 304 708), US-A 4 374 209 and DE-A 32 31 497.

The polyether polyols can, like the polyester polyols used individually or in the form of mixtures. Further you can use the graft polyols or polyesters polyols and the hydroxyl-containing polyester amides, Polyacetals, polycarbonates and / or polyether polyamines to be mixed.  

As polyacetals containing hydroxyl groups such. B. from Glycols, such as diethylene glycol, triethylene glycol, 4,4'-dihy droxyethoxy-diphenyl-dimethylmethane, hexanediol and formaldehyde hyd producible compounds in question. Also through polymer suitable polyacetals produce.

Such polycarbonates come as hydroxyl groups of the type known per se, 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, e.g. B. Diphenyl carbonate, or phosgene can be produced.

The polyester amides include e.g. B. from polyvalent, ge saturated and / or unsaturated carboxylic acids or their An hydride and polyvalent saturated and / or unsaturated Amino alcohols or mixtures of polyhydric alcohols and Amino alcohols and / or polyamines obtained, mainly li near condensates.

Suitable polyether polyamines can be obtained from the above Polyether polyols are produced by known processes the. The cyanoalkylation of Po may be mentioned by way of example lyoxyalkylene polyols and subsequent hydrogenation of the gebil Detected nitrile (US 3,267,050) or the partially or fully permanent amination of polyoxyalkylene polyols with amines or ammonia in the presence of hydrogen and catalysts (DE 12 15 373).

c) The rigid polyurethane foams can be with or without with use of chain extension and / or crosslinking agents teln (c) are produced. To modify the mechani properties, z. B. the hardness, but can be too set of chain extenders, crosslinking agents or if appropriate, mixtures thereof prove to be advantageous sen. As a chain extender and / or crosslinking agent Diols and / or triols with molecular weights are used less than 400, preferably from 60 to 300. Considerable come for example aliphatic, cycloaliphatic and / or araliphatic diols with 2 to 14, preferably 4 to 10 Carbon atoms such as B. ethylene glycol, 1,3-propanediol, Decanediol-1,10, o-, m-, p-dihydroxycyclohexane, diethylene glycol kol, dipropylene glycol and preferably 1,4-butanediol, hexane diol-1,6 and bis (2-hydroxy-ethyl) hydroquinone, triols, such as 1,2,4-, 1,3,5-trihydroxycyclohexane, glycerin and trimethy lolpropane and low molecular weight hydroxyl-containing polyal  kylene oxides based on ethylene and / or 1,2-propylene oxide and the aforementioned diols and / or triols as starter molecules.

If Ket. Is used to manufacture the rigid polyurethane foams ten extenders, crosslinking agents or mixtures there of application, they are conveniently in one Amount from 0 to 20% by weight, preferably from 2 to 8% by weight, based on the weight of component (b).

d) To blowing agents which are used to manufacture the polyurethane hard foams are used, preferably include water, the re with isocyanate groups to form carbon dioxide acts, and / or physically acting blowing agents. Suitable are liquids which are compared to the organic ones modified polyisocyanates are inert and boil points below 100 ° C, preferably below 50 ° C, especially between have -50 ° C and 30 ° C at atmospheric pressure, so that it under the influence of the exothermic polyaddition reaction evaporate. Examples of such, preferably usable Liquids are alkanes such as heptane, hexane, n- and iso-pen tan, preferably technical mixtures of n- and iso-penta nen, n- and iso-butane and propane, cycloalkanes, such as cyclopen tan and / or cyclohexane, ethers such as furan, dimethyl ether and Diethyl ether, ketones such as acetone and methyl ethyl ketone, Car alkyl acid esters, such as methyl formate, dimethyl oxalate and Ethyl acetate and halogenated hydrocarbons, such as Methylene chloride, dichloromonofluoromethane, difluoromethane, tri fluoromethane, difluoroethane, tetrafluoroethane, chlorodifluor ethane, 1,1-dichloro-2,2,2-trifluoroethane, 2,2-dichloro-2- fluoroethane and heptafluoropropane. Mixtures of this cute Rigid liquids with each other and / or with others substituted or unsubstituted hydrocarbons be used. Organic carbon are also suitable acids, such as B. formic acid, acetic acid, oxalic acid, Rici nolic acid and compounds containing carboxyl groups.

Water, chlorodifluoromethane, Chlorodifluoroethanes, dichlorofluoroethanes, pentane mixtures, Cyclohexane and mixtures of at least two of these propellants medium, e.g. B. mixtures of water and cyclohexane, mixtures from chlorodifluoromethane and 1-chloro-2,2-difluoroethane and counter also water.

These blowing agents are usually added to component (b) set. However, you can use the isocyanate component (a) or as a combination of both component (b) and iso  cyanate component (a) or premixes of these components be added with the other structural components.

The amount of blowing agent or blowing agents used mixture is 1 to 25 wt .-%, preferably 5 to 15% by weight, based in each case on the polyol component (b).

If water serves as a blowing agent, it is preferably the Build-up component (b) in an amount of 0.5 to 5 wt .-%, be pulled on the build component (b) added. The Wasserzu set can be used in combination with the other written propellants.

e) As catalysts (e) for the production of polyurethane hard Foams are used in particular compounds that the reaction of reactive hydrogen atoms, especially Hy Compounds of component (b) containing droxyl groups and optionally (c) with the organic, optionally accelerate modified polyisocyanates (a) strongly.

Basic polyurethane is expediently used catalysts, for example tertiary amines, such as triethyl amine, tributylamine, dimethylbenzylamine, dicyclohexylmethyl amine, dimethylcyclohexylamine, N, N, N ′, N′-tetramethyl-diamino diethyl ether, bis (dimethylaminopropyl) urea, N-methyl or N-ethylmorpholine, N-cyclohexylmorpholine, N, N, N ′, N′-tetramethylethylenediamine, N, N, N ′, N′-tetramethylbutanediamine, N, N, N ', N'-tetramethylhexanediamine-1,6, pentamethyldiethylene triamine, dimethylpiperazine, N-dimethylaminoethylpiperidine, 1,2-dimethylimidazole, 1-azabicyclo (2,2,0) octane, 1,4-diaza bicyclo (2,2,2) octane (Dabco) and alkanolamine compounds such as Triethanolamine, triisopropanolamine, N-methyl and N-ethyl diethanolamine, dimethylaminoethanol, 2- (N, N-dimethylamino ethoxy) ethanol, N, N ′, N ′ ′ - tris (dialkylaminoalkyl) hexahydrotri azine, e.g. B. N, N ', N' '- tris- (dimethylaminopropyl) -s-hexahydro triazine, and triethylenediamine. However, Me are also suitable tall salts such as ferric chloride, zinc chloride, lead octoate and preferably tin salts such as tin dioctoate, tin diethylhexoate and dibutyltin dilaurate and in particular mixtures of tertiary amines and organic tin salts.

Other suitable catalysts are: amidines, such as 2,3-dimethyl-3,4,5,6-tetrahydropyrimidine, tetraalkylammonium hydroxides, such as tetramethylammonium hydroxide, alkali hydroxides, such as sodium hydroxide and alkali alcoholates, such as sodium methylate and potassium isopropylate, and alkali salts of long-chain Fatty acids with 10 to 20 carbon atoms and optionally sides  permanent OH groups. Preferably 0.001 to 5% by weight, in particular 0.05 to 2% by weight, of catalyst or Catalyst combination, based on the weight of the components te (b).

f) According to the invention, the method is in the presence of Dialkalihy drug phosphate (f) performed.

Suitable dialkali hydrogen phosphates are, for example Disodium hydrogen phosphate and dipotassium hydrogen phosphate. Before dipotassium hydrogen phosphate is preferably used.

The dialkali hydrogen phosphate can be used in combination with others Alkali metal salts are used. Are suitable for this for example potassium acetate and potassium octoate. Preferably Potassium acetate is used.

A combination of is particularly preferably used Dipotassium hydrogen phosphate and potassium acetate.

The dialkali used in the process according to the invention Hydrogen phosphate is used in such an amount that an alkali content of 50 to 2500 ppm, preferably 100 up to 1500 ppm, based on the amount of component b), he enough. Is the dialkali hydrogen phosphate in combination with other alkali metal salts used, so is the alkali metal use tall salt combination in such an amount that a total alkali content of 50 to 2500 ppm, preferred as 100 to 1500 ppm, based on the amount of components b) is achieved.

The dialkali hydrogen phosphate or the combination of dialka Hydrogen phosphate and other alkali metal salts are common added to component (b). The invention Alkaline levels can occur when assembling the components (b) to (g) for component (A).

In the event that as component (b) an alkaline ka Talysed alkylene oxide attachment at H-functional start substances produced and neutralized with phosphoric acid ter polyether alcohol is used, it is possible to subsequent work so that an alkali hold from 50 to 2500 ppm, preferably 100 to 1500 ppm, in Form of dialkali hydrogen phosphate in component b) ver remains.  

Of course, a certain basic amount can also be added Dialkalihydrogenphosphat during the production process of Component (b) can be set for each Intended use by appropriate additions of the Invention can be adapted according to alkali metal salts.

The presence of dialkali hydrogen phosphate, in particular Dipotassium hydrogen phosphate, in the manufacture of polyure than rigid foams has been used to minimize afterblowing hens and thus to shorten the demolding times proven. It has also been shown to be a cheap one Effect through the combination of dialkali hydrogen phosphate, especially dipotassium hydrogen phosphate, with other alkali metal salts, especially potassium acetate, is achieved.

g) The reaction mixture for producing the polyurethane hard If necessary, foams can also be used for other aids and / or additives (g) are incorporated. Be mentioned for example surface-active substances, foam stabilizers gates, cell regulators, fillers, dyes, pigments, flame Protective, hydrolysis, fungistatic and bak teriostatic substances.

As surface-active substances such. B. Connections in Consider which to support the homogenization of the Serve as starting materials and are also suitable if necessary, regulate the cell structure of plastics. Be mentioned for example emulsifiers, such as the sodium salts of Ricinus oil sulfates or of fatty acids and salts of fatty acids with Amines, e.g. B. oleic acid diethylamine, stearic acid diethanola min, ricinoleic acid diethanolamine, salts of sulfonic acids, e.g. B. alkali or ammonium salts of dodecylbenzene or di naphthylmethane disulfonic acid and ricinoleic acid; Foam stabilizer catalysts, such as siloxane-oxalkylene copolymers and others Organopolysiloxanes, ethoxylated alkylphenols, ethoxylated Fatty alcohols, paraffin oils, castor oil or ricinoleic acid esters, Turkish red oil and peanut oil, and cell regulators such as paraffins, Fatty alcohols and dimethylpolysiloxanes. To improve the Emulsifying effect, the cell structure and / or stabilization of the The oligomers described above are also suitable for foam Acrylates with polyoxyalkylene and fluoroalkane residues as sides groups. The surface-active substances are becoming more common in amounts of 0.01 to 5% by weight, based on 100% by weight component (b) applied.  

As fillers, in particular reinforcing fillers, are the usual organic and anorga known per se African fillers, reinforcing agents, weighting agents, Means to improve the abrasion behavior in paint ben to understand coating agents, etc. In particular Examples include: inorganic fillers such as silica minerals, for example layered silicates such as antigo rit, serpentine, hornblende, amphibole, chrisotile and talc, Metal oxides such as kaolin, aluminum oxides, titanium oxides and egg senoxides, metal salts such as chalk, heavy spar and inorganic pigments such as cadmium sulfide and zinc sulfide, and glass u. a .. Kaolin (China Clay), aluminum are preferably used minium silicate and coprecipitates made from barium sulfate and aluminum silicate as well as natural and synthetic fibrous Mi minerals such as wollastonite, metal and especially glass fibers of different lengths, which may be mediated can. Organic fillers come in, for example Consideration: coal, melamine, rosin, cyclopentadienyl resins and graft polymers and cellulose fibers, polyamide, Po lyacrylonitrile, polyurethane, polyester fibers on the bottom location of aromatic and / or aliphatic dicarboxylic acids star and especially carbon fibers.

The inorganic and organic fillers can be used individually or used as mixtures and are the reaction mixture advantageously in amounts of 0.5 to 50% by weight, preferably 1 to 40% by weight, based on the weight of the com components (a) to (c), but the content of Mats, fleeces and fabrics made of natural and synthetic Fibers can reach values of up to 80% by weight.

Suitable flame retardants are, for example, tricresyl phosphate, tris (2-chloroethyl) phosphate, tris (2-chloroprop pyl) phosphate, tris (1,3-dichloropropyl) phosphate, tris (2,3-di bromopropyl) phosphate, tetrakis (2-chloroethyl) ethylene diphosp has, dimethylmethanephosphonate, diethanolaminomethylphosphon acid diethyl ester and commercially available halogen-containing flame protective polyols.

In addition to the halogen-substituted phosphates already mentioned inorganic or organic flame retardants, such as red phosphorus, aluminum oxide hydrate, antimony trioxide, Ar senoxide, ammonium polyphosphate and calcium sulfate, expandable graphite or cyanuric acid derivatives, such as. B. melamine, or mixtures from at least two flame retardants, such as. B. ammonium po lyphosphates and melamine and optionally corn starch or Ammonium polyphosphate, melamine and expandable graphite and / or  also aromatic polyester to flame retard the bottom lyisocyanate polyaddition products are used. Generally mine has proven to be expedient, 5 to 50 wt .-%, preferably 5 to 25% by weight of said flame retardant tel, based on component (b).

Details of the other usual above mentioned Auxiliaries and additives are in the specialist literature, for example se of the monograph by J.H. Saunders and K.C. Fresh "high Polymers "Volume XVI, Polyurethanes, Parts 1 and 2, Publisher In terscience Publishers 1962 or 1964, or the plastic Manual, Polyurethane, Volume VII, Hanser-Verlag, Munich, Vienna, 1st and 2nd editions, 1966 and 1983.

For the production of rigid polyurethane foams, the orga African and / or modified organic polyisocyanates (a), higher molecular weight compounds with at least two reactive was seratomatomen (b) and optionally chain extension and / or Crosslinking agent (c) in such amounts for implementation brings that the equivalence ratio of NCO groups of the Polyiso cyanate (a) to the sum of the reactive hydrogen atoms of the compo nenten (b) and optionally (c) 0.85 to 1.25: 1, preferably 0.95 to 1.15: 1 and in particular 1 to 1.05: 1. if the Rigid polyurethane foams at least partially isocyanurate group pen bound, a ratio of NCO groups of the polyisocyanates (a) to the sum of the reactive What hydrogen atoms of component (b) and optionally (c) of 1.5 to 60: 1, preferably 1.5 to 8: 1, applied.

The rigid polyurethane foams are advantageously after the one shot process, for example with the help of high pressure or Low pressure technology in open or closed molds witness, for example, metallic molds. Continuous application of the reaction mixture is also customary on suitable belt lines for the production of panels.

It has proven to be particularly advantageous after the two-com to work on component processes and the structural components (b), (d), (e), (f) and optionally (c) and (g) in component (A) combine and as component (B) the organic and / or modes organic polyisocyanates (a) or mixtures of the mentioned polyisocyanates and optionally blowing agent (d) use.

The starting components are at a temperature of 15 to 90 ° C, preferably from 20 to 60 ° C and in particular from 20 to 35 ° C, mixed and raised in the open or, if necessary, under  pressure into the closed mold or at a continuous workstation on a belt that the Reak absorbing mass, applied. The mixing can, as be has already been demonstrated, mechanically using a stirrer or a Stirring screw. The mold temperature be appropriately carries 20 to 110 ° C, preferably 30 to 60 ° C and especially 45 to 50 ° C.

The polyures produced by the process according to the invention than rigid foams have a density of 0.02 to 0.30 g / cm³, preferably from 0.025 to 0.24 g / cm³ and in particular from 0.03 up to 0.1 g / cm³. They are particularly suitable as insulation mats rial in the construction and refrigeration sector, e.g. B. as an intermediate layer for Sandwich elements or for foaming refrigerator and cooling chest housings.

The invention is illustrated in the following exemplary embodiments ago explained.

Example 1 - Comparative Example

100 parts by weight of an A component, consisting of
48.50 parts by weight of a highly functional sugar polyether (hydroxyl number 493 mgKOH / g),
20.70 parts by weight of a rigid foam polyether based on sugar-glycerol (hydroxyl number 500 mgKOH / g),
8.10 parts by weight of a propylene oxide-containing difunctional polyol (hydroxyl number 56 mgKOH / g),
2.50 parts by weight of the silicone stabilizer SR 321 from OSi Specialties Inc, Danbury / Conn.),
0.30 parts by weight of Dabco BL 11 from Air Products,
3.10 parts by weight of water and
15.20 parts by weight of R 11,
were converted to a rigid foam with 143.6 parts by weight of a polyphenylpolymethylene polyisocyanate (raw MDI).

Example 2

The A component according to Example 1 was 250 ppm in the form of potassium of dipotassium hydrogen phosphate added. Then it became analog Example 1 made a rigid foam.  

Example 3 - Comparative Example

100 parts by weight of an A component, consisting of
68.42 parts by weight of a rigid foam polyether based on sugar / glycerol (hydroxyl number 440 mgKOH / g),
9.67 parts by weight of an amine-started polyether (hydroxyl number 115 mgKOH / g),
4.60 parts by weight of a propylene oxide-containing polyether (hydroxyl number 250 mgKOH / g),
2.03 parts by weight of dimethylcyclohexylamine (DMCHA),
2.00 parts by weight of the silicone stabilizer SR 321 from OSi,
2.14 parts by weight of water and
11.14 parts by weight of cyclopentane,
were converted to a rigid foam with 121.3 parts by weight of a polyphenylpolymethylene polyisocyanate (raw MDI).

Example 4

The A component according to Example 3 was 1000 ppm of potassium in the form of dipotassium hydrogen phosphate added. Then it became analog Example 3 made a rigid foam.

Example 5

1500 ppm of potassium were added to the A component according to Example 3 puts. 1000 ppm as dipotassium hydrogen phosphate and 500 ppm used as potassium acetate. According to Bei game 3 a corresponding rigid foam is produced.

Example 6 - Comparative Example

100 parts by weight of an A component, consisting of
40.10 parts by weight of a rigid foam polyether based on sugar glycerol (hydroxyl number 440 mgKOH / g),
25.00 parts by weight of a propylene oxide-containing difunctional polyol (hydroxyl number 56 mgKOH / g),
15.10 parts by weight of a polyether alcohol based on propylene oxide (hydroxyl number 400 mgKOH / g),
12.00 parts by weight of an additive flame retardant based on phosphorus (T131 from BASF Aktiengesellschaft),
1.50 parts by weight of the SR 321 silicone stabilizer from OSi,
2.20 parts by weight of DMCHA and
4.10 parts by weight of water,
were converted to a rigid foam with 134.6 parts by weight of a polyphenylpolymethylene polyisocyanate (raw MDI).

Example 7

The A component according to Example 6 was 400 ppm potassium in the form of dipotassium hydrogen phosphate added. Then it became analog Example 6 made a rigid foam.

Example 8

The A component according to Example 6 was 250 ppm potassium Dipotassium hydrogen phosphate and 300 ppm potassium in the form of potassium added acetate. Then an ent was analogous to Example 6 speaking rigid foam.

Driving the Hart outlined in Examples 1-8 Foam samples were taken on a Bosch lance (50 mm thick) and on one Box shape (25 l; thickness 90 mm) measured. The results are in shown in Tables 1 to 5.

It turned out that regardless of the blowing agent chosen - compared to rigid polyurethane foams without the invention Alkali salt additive - the driving properties by adding Dialkali hydrogen phosphate, especially dipotassium hydrogen phosphate, and its combinations with potassium acetate significantly improved and the annoying cracking have been reduced, whereby a green increased demolding behavior could be achieved.

Table 1

Hard foam (lance shape)

Blowing agent: R¹¹

Table 2

Hard foam expansion (box shape)

Blowing agent: R¹¹

Table 3

Hard foam (lance shape)

Blowing agent: cyclopentane

Table 4

Hard foam expansion (box shape)

Blowing agent: cyclopentane

Table 5

Hard foam expansion (box shape)

Blowing agent: water

Claims (14)

1. Process for the production of rigid polyurethane foams with reduced post-expansion and shorter demolding times by implementing

• a) organic and / or modified organic polyiso cyanates with
• b) at least one higher molecular weight compound with at least two reactive hydrogen atoms and optionally
• c) low molecular weight chain extenders and / or crosslinking agents in the presence of
• d) blowing agents,
• e) catalysts
• f) alkali metal salts and optionally
• g) further auxiliaries and / or additives,

characterized in that dialkalihy drug phosphate with an alkali content of 50 to 2500 ppm, based on the amount of components b) to g), is used as the alkali metal salt. 2. The method according to claim 1, characterized in that the added dialkali hydrogen phosphate with an alkali content of 100 to 1500 ppm, based on the amount of components b) to g). 3. The method according to claim 1 or 2, characterized in that the dialkali hydrogen phosphate of component b) is added becomes. 4. The method according to any one of claims 1 to 3, characterized records that the Dialkalihydrogenphosphat in combination with other alkali metal salts are used. 5. The method according to any one of claims 1 to 4, characterized records that the Dialkalihydrogenphosphat in combination with Potassium acetate is used.   6. The method according to any one of claims 1 to 5, characterized records that the total alkali metal salts added an alkali content of 50 to 2500 ppm, based on the amount of components b) to g). 7. The method according to any one of claims 1 to 6, characterized records that as dialkalihydrogen phosphate dipotassium hydrogen phosphate is used. 8. Rigid polyurethane foams with reduced drag and shorter demolding times, containing at least one alkali metal salt and optionally other known per se Auxiliaries and / or additives, characterized in that that as the alkali metal salt dialkali hydrogen phosphate with a Alkali content of 50 to 2500 ppm, based on the amount of Components b) to g) is included. 9. rigid polyurethane foams according to claim 8, characterized records that the Dialkalihydrogenphosphat in combination with other alkali metal salts is included. 10. rigid polyurethane foams according to one of claims 8 or 9, characterized in that the dialkali hydrogen phosphate in combination with potassium acetate. 11. Rigid polyurethane foams according to one of claims 8 to 10, characterized in that the dialkali hydrogen phosphate Dipotassium hydrogen phosphate is. 12. Rigid polyurethane foams according to one of claims 8 to 11, characterized in that the total alkali content 50th up to 2500 ppm, based on the amount of components contained ten b) to g). 13. Use of the rigid polyurethane foams according to one of the Claims 8 to 12 as insulation material in construction and refrigeration sector.