DE102004053374B4 - Polyurethane rigid foams containing acrylates and process for their preparation - Google Patents

Abstract

Rigid polyurethane foam with a density between 20 kg / m3 and 200 kg / m3, characterized in that the rigid polyurethane foam contains as compounds (i) one of the following compounds bisphenol A diglycidyl diacrylate and / or 1,4-butanediol diglycidyl diacrylate,

Description

Bisphenol-A-diglycidyldiacrylat und/oder

1,4-Butandioldiglycidyldiacrylat, und/oder ein Umsetzungsprodukt dieser Verbindungen (i) mit den weiteren Ausgangsstoffen zur Herstellung des Polyurethanhartschaumstoffs, insbesondere den Verbindungen (i) selbst, den Isocyanaten (a) und/oder den gegenüber Isocyanaten reaktiven Verbindungen (b) enthält. Aufgrund der Reaktivität der Verbindungen (i) bezieht sich die Erfindung somit nicht nur auf die Hartschaumstoffe, in denen sich die Verbindungen (i) als solches nachweisen lassen, sondern ausdrücklich auch auf Hartschaumstoffe, in denen Umsetzungsprodukte dieser Verbindungen (i), beispielsweise mit Isocyanaten oder anderen Verbindungen (i) oder anderen Komponenten zur Herstellung der Hartschaumstoffe enthalten sind. Des weiteren betrifft die Erfindung Verfahren zur Herstellung dieser Hartschaumstoffe.The invention relates to rigid polyurethane foams having a density between 20 kg / m ³ and 200 kg / m ³ , preferably between 20 kg / m ³ and 100 kg / m ³ , wherein the rigid polyurethane foam contains as compounds (i) the following compounds:

Bisphenol A diglycidyl diacrylate and / or

1,4-Butandioldiglycidyldiacrylat, and / or a reaction product of these compounds (i) with the other starting materials for producing the rigid polyurethane foam, in particular the compounds (i) themselves, the isocyanates (a) and / or the isocyanate-reactive compounds (b) , Due to the reactivity of the compounds (i), the invention thus relates not only to the rigid foams in which the compounds (i) can be detected as such, but also expressly to rigid foams in which reaction products of these compounds (i), for example with isocyanates or other compounds (i) or other components for producing the rigid foams. Furthermore, the invention relates to processes for producing these rigid foams.

Polyurethane rigid foams and processes for producing these foams are well known and widely described.

The DE 199 19 826 A1 For example, a process for the production of polyurethane foams is described, in which reaction α, β-unsaturated carboxylic acids, α, β-unsaturated ketones and / or α, β-unsaturated aldehydes are used.

The object of the invention was to develop rigid polyurethane foams with a density between 20 kg / m ³ and 200 kg / m ³ , preferably between 20 kg / m ³ and 100 kg / m ³ , with a stable, well-flowing and fast-curing reaction mixture can be produced with which even large, complicated shapes can be filled. Here, the polyurethane foam should have a good, ie low thermal conductivity even after aging.

The problem could be solved by the rigid polyurethane foams, which may optionally have isocyanurate structures.

The use of the acrylates (i) according to the invention optimizes the network density in the rigid polyurethane foam, i. H. An additional crosslinking can be introduced into the foam via the acrylates (i). The used acrylic resin (i) is comparable in OHZ and viscosity with the commonly used polyols. The reactivity and flow behavior of the polyol component is not significantly affected by the use of the acrylic resin. The heat of reaction liberated in the reaction of polyol and isocyanate is sufficient for the radical polymerization of the acrylic resin (i).

The polymeric acrylic resin reinforces the network of rigid polyurethane foam and gives it better mechanical properties at the same density, without the other characteristics, z. As the thermal conductivity, deterioration occur. Since the increased cross-linking occurs only after flowing, ie during the foaming, there are no, even when filling in larger, more complicated forms Impairment. The crosslinking reaction of the acrylates (i) via the unsaturated units can be started by the resulting heat of reaction during the PU reaction. Initiators, ie known, preferably free-radical initiators for the polymerization reaction of the acrylates (i) can be used, but are not absolutely necessary.

Furthermore, the use of the compounds (i) shows improved thermal conductivity and aging. Surprisingly, it has been found that the mechanical and thermal behavior can be improved.

Achieving higher levels of crosslinking over the PU raw materials used as standard is hardly feasible. The use of PMDI (F ~ 2.7) is more common. Highly functional isocyanates are not available on an industrial scale. For high crosslinking, highly functional sucrose polyetherols are used. An increase in the functionality of the polyols is hardly feasible in practice, since there are no commercially available low-cost starters available. In addition, a higher functionality of the polyol leads to a higher viscosity, which in turn is undesirable and would significantly affect the processability.

These disadvantages can be overcome by the use according to the invention of the compounds (i), i. H. the acrylates are avoided. Surprisingly, the use of the acrylates (i) leads to the formation of a stable, well-flowing and rapidly curing foam. The reaction mixture can fill large, complicated shapes. Crosslinking by the acrylates results in an abrupt increase in viscosity and improves strength despite low functionality in the polyol component. After the polymerization of acrylates can be immediately removed from the mold.

Bisphenol-A-diglycidyldiacrylat
und/oder

1,4-Butandioldiglycidyldiacrylat. The use of acrylates is out WO 91/13112 and DE-A 3127945 known, but not for the rigid foams of the invention. Especially with regard to these products, however, it was particularly advantageous and surprising for a person skilled in the art to achieve the abovementioned advantages by using the following acrylates.

Bisphenol A diglycidyldiacrylat
and or

1,4-Butandioldiglycidyldiacrylat.

Particularly preferred is bisphenol A diglycidyl diacrylate in 20 wt .-% 1,6-hexanediol diacrylate or 15 wt .-% n-butyl acetate, each based on the total weight of the mixture.

Bisphenol-A-diglycidyldiacrylat und/oder

1,4-Butandioldiglycidyldiacrylat. Process for the preparation of rigid polyurethane foams by reacting (a) isocyanates with (b) isocyanate-reactive compounds, preferably by reacting (a) isocyanates with (b) compounds having isocyanate-reactive hydrogen atoms, preferably in the presence of catalysts (d), (c ) Propellant and optionally (e) additives, particularly preferably foam stabilizers and flame retardants is well known. The inventive method is characterized by the fact that one carries out the reaction in the presence of compounds (i), wherein as compounds (i) the following compounds are used:

Bisphenol A diglycidyl diacrylate and / or

1,4-Butandioldiglycidyldiacrylat.

• (a) Als Polyisocyanate kommen die üblichen aliphatischen, cycloaliphatischen und insbesondere aromatischen Di- und/oder Polyisocyanate in Frage. Bevorzugt verwendet werden Toluylendiisocyanat (TDI), Diphenylmethandiisocyanat (MDI) und insbesondere Gemische aus Diphenylmethandiisocyanat und Polyphenylenpolymethylenpolyisocyanaten (Roh-MDI). Die Isocyanate können auch modifiziert sein, beispielsweise durch Einbau von Uretdion-, Carbamat-, Isocyanurat-, Carbodiimid-, Allophanat- und insbesondere Urethangruppen. Zur Herstellung von Polyurethan-Hartschaumstoffen wird insbesondere Roh-MDI eingesetzt. Bevorzugt ist weiterhin der Einsatz von Polymer-MDI als Isocyanat (a). Im Stand der Technik ist es gegebenenfalls üblich, Isocyanuratgruppen in das Polyisocyanat einzubauen. Die Isocyanurat-Bildung führt zu flammwidrigen PIR-Schaumstoffen, welche bevorzugt im technischen Hartschaum, beispielsweise im Bauwesen als Dämmplatte, Sandwichelemente und LKW Aufbauten eingesetzt werden.
• (b) Als Verbindungen mit mindestens zwei gegenüber Isocyanat reaktiven Gruppen, das heißt mit mindestens zwei mit Isocyanatgruppen reaktiven Wasserstoffatomen können allgemein Verbindungen eingesetzt werden, die nachfolgend allgemein beschrieben werden. Als Verbindungen mit mindestens zwei gegenüber Isocyanat reaktiven Gruppen kommen insbesondere solche in Frage, die zwei oder mehrere reaktive Gruppen, ausgewählt aus OH-Gruppen, SH-Gruppen, NH-Gruppen, NH₂-Gruppen und CH-aciden Gruppen, wie z. B. β-Diketo-Gruppen, in Molekül tragen. Zur Herstellung der nach dem erfindungsgemäßen Verfahren bevorzugt hergestellten Polyurethanhartschaumstoffe kommen insbesondere Verbindungen mit 2 bis 8 OH-Gruppen zum Einsatz. Vorzugsweise eingesetzt werden Polyetherole und/oder Polyesterole. Die Hydroxylzahl der verwendeten Polyetherole und/oder Polyesterole beträgt bei der Herstellung von Polyurethanhartschaumstoffen vorzugsweise 100 bis 850 mg KOH/g, besonders bevorzugt 200 bis 600 mg KOH/g, die Molekulargewichte sind vorzugsweise größer als 400 g/mol. Bevorzugt enthält Komponente (b) Polyetherpolyole, die nach bekannten Verfahren, beispielsweise durch anionische Polymerisation mit Alkalihydroxiden, wie Natrium- oder Kaliumhydroxid oder Alkalialkoholaten, wie Natriummethylat, Natrium- oder Kaliumethylat oder Kaliumisopropylat als Katalysatoren und unter Zusatz mindestens eines Startermoleküls das 2 bis 8, vorzugsweise 3 bis 8 reaktive Wasserstoffatome gebunden enthält, oder durch kationische Polymerisation mit Lewis-Säuren, wie Antimonpentachlorid, Borfluorid-Etherat u. a. oder Bleicherde als Katalysatoren aus einem oder mehreren Alkylenoxiden mit 2 bis 4 Kohlenstoffatomen im Alkylenrest hergestellt werden. Geeignete Alkylenoxide sind beispielsweise Tetrahydrofuran, 1,3-Propylenoxid, 1,2- bzw. 2,3-Butylenoxid, Styroloxid und vorzugsweise Ethylenoxid und 1,2-Propylenoxid. Die Alkylenoxide können einzeln, alternierend nacheinander oder als Mischungen verwendet werden. Als Startermoleküle kommen beispielsweise in Betracht Glycerin, Trimethylolpropan, Pentaerythrit, Sacharose, Sorbit, Methylamin, Ethylamin, Isopropylamin, Butylamin, Benzylamin, Anilin, Toluidin, Toluoldiamin, Naphtylamin, Ethylendiamin, Diethylentriamin, 4,4'-Methylendianilin, 1,3,-Propandiamin, 1,6-Hexandiamin, Ethanolamin, Diethanolamin, Triethanolamin sowie andere zwei oder mehrwertige Alkohole oder ein oder mehrwertige Amine. Ferner kann die Komponente (b) optional Polyesterole, Kettenverlängerungs- und/oder Vernetzungsmitteln enthalten. Als Kettenverlängerungs- und/oder Vernetzungsmittel kommen insbesondere zwei- oder dreifunktionelle Amine und Alkohole, insbesondere Diole und/oder Triole mit Molekulargewichten kleiner als 400 g/mol, vorzugsweise von 60 bis 300, zum Einsatz. Bevorzugt setzt man als Verbindung (b) Polyetherpolyole und/oder Polyesterpolyole mit einer Hydroxylzahl größer 160, besonders bevorzugt größer 200 mg KOH/g und besonders bevorzugt einer Funktionalität zwischen 2,9 und 8 ein. Besonders bevorzugt setzt man als gegenüber Isocyanaten reaktive Verbindungen (b) Polyetherpolyole ein, die ein Äquivalentgewicht, d. h. Molekulargewicht dividiert durch die Funktionalität, kleiner 400 g/mol, bevorzugt kleiner 200 g/mol aufweisen. Die Verbindung (b) liegt im allgemeinen in flüssiger Form vor.

Particularly preferred is bisphenol A diglycidyl diacrylate in 20 wt .-% 1,6-hexanediol diacrylate or 15 wt .-% n-butyl acetate, each based on the total weight of the mixture. The following can be said in detail about the other components (a) to (e).

• (A) Suitable polyisocyanates are the customary aliphatic, cycloaliphatic and in particular aromatic di- and / or polyisocyanates. Preferably used are tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI) and in particular mixtures of diphenylmethane diisocyanate and polyphenylene polymethylene polyisocyanates (crude MDI). The isocyanates may also be modified, for example by incorporation of uretdione, carbamate, isocyanurate, carbodiimide, allophanate and in particular urethane groups. For the production of rigid polyurethane foams in particular crude MDI is used. Furthermore, the use of polymer MDI as isocyanate (a) is preferred. In the prior art, it may be customary to incorporate isocyanurate groups in the polyisocyanate. The formation of isocyanurate leads to flame-resistant PIR foams, which are preferably used in industrial rigid foam, for example in construction as an insulating board, sandwich panels and truck bodies.
• (b) As compounds having at least two isocyanate-reactive groups, that is to say having at least two isocyanate-reactive hydrogen atoms, it is generally possible to use compounds which are generally described below. Suitable compounds having at least two isocyanate-reactive groups are, in particular, those which have two or more reactive groups selected from OH groups, SH groups, NH groups, NH ₂ groups and CH-acidic groups, such as. B. β-diketo groups, carry in molecule. For the preparation of the rigid polyurethane foams preferably produced by the process according to the invention, in particular compounds having 2 to 8 OH groups are used. Preferably used are polyetherols and / or polyesterols. The hydroxyl number of the polyetherols and / or polyesterols used in the production of rigid polyurethane foams is preferably 100 to 850 mg KOH / g, more preferably 200 to 600 mg KOH / g, the molecular weights are preferably greater than 400 g / mol. Component (b) preferably comprises polyetherpolyols prepared by known processes, for example by anionic polymerization with alkali metal hydroxides, such as sodium or potassium hydroxide or alkali metal alkoxides, such as sodium methylate, sodium or potassium ethylate or potassium isopropoxide as catalysts and with the addition of at least one starter molecule 2 to 8, preferably contains 3 to 8 bonded reactive hydrogen atoms, or be prepared by cationic polymerization with Lewis acids such as antimony pentachloride, boron fluoride etherate, inter alia, or bleaching earth as catalysts of one or more alkylene oxides having 2 to 4 carbon atoms in the alkylene radical. Suitable alkylene oxides are, for example, tetrahydrofuran, 1,3-propylene oxide, 1,2- or 2,3-butylene oxide, styrene oxide and preferably ethylene oxide and 1,2-propylene oxide. The alkylene oxides can be used individually, alternately in succession or as mixtures. Suitable starter molecules are, for example, glycerol, trimethylolpropane, pentaerythritol, sucrose, sorbitol, methylamine, ethylamine, isopropylamine, butylamine, benzylamine, aniline, toluidine, toluenediamine, naphthylamine, ethylenediamine, diethylenetriamine, 4,4'-methylenedianiline, 1,3, - Propanediamine, 1,6-hexanediamine, ethanolamine, diethanolamine, triethanolamine and other dihydric or polyhydric alcohols or mono- or polyhydric amines. Further, component (b) may optionally contain polyesterols, chain extenders and / or crosslinkers. Suitable chain extenders and / or crosslinking agents are, in particular, difunctional or trifunctional amines and alcohols, in particular diols and / or triols having molecular weights of less than 400 g / mol, preferably from 60 to 300. Preference is given to using compound (b) as polyetherpolyols and / or polyesterpolyols having a hydroxyl number greater than 160, more preferably greater than 200 mg KOH / g, and especially preferably has a functionality between 2.9 and 8. Particular preference is given to using isocyanate-reactive compounds (b) as polyether polyols which have an equivalent weight, ie molecular weight divided by the functionality, less than 400 g / mol, preferably less than 200 g / mol. The compound (b) is generally in liquid form.

As blowing agent component (c) hydrocarbons are preferably used. These can be used in admixture with water and / or other physical blowing agents. This refers to compounds which are dissolved or emulsified in the starting materials of polyurethane production and evaporate under the conditions of polyurethane formation. These are, for example, hydrocarbons, halogenated hydrocarbons, and other compounds, such as perfluorinated alkanes, such as perfluorohexane, chlorofluorocarbons, and ethers, esters, ketones and / or acetals. The blowing agent component (c) is preferably added in an amount of 2 to 45% by weight, preferably 4 to 30% by weight, particularly preferably 5 to 20% by weight, based on the total weight of the components (b) to ( e) a. It is further preferred that the blowing agent component (c) less than 5 wt .-%, more preferably less than 2 wt .-%, more preferably less than 1 wt .-%, in particular 0 wt .-%, based on the total weight of components (b) to (e), chlorofluorocarbons, chlorinated hydrocarbons or fluorocarbons. In a preferred embodiment, the blowing agent mixture (c) contains hydrocarbons, in particular n-pentane and / or cyclopentane and water. Particularly preferred hydrocarbons are n-pentane, cyclopentane, iso-pentane and / or mixtures of the isomers. In particular, cyclopentane and / or n-pentane are used as the blowing agent (c).

As catalysts (d) it is possible to use catalysts (d) generally known from polyurethane chemistry.

The reaction of (a) with (b) is optionally carried out in the presence of (e) additives, such. As flame retardants, fillers, cell regulators, foam stabilizers, surface-active compounds and / or stabilizers against oxidative, thermal or microbial degradation or aging, preferably flame retardants and / or foam stabilizers. Foam stabilizers are substances which promote the formation of a regular cell structure during foaming. For example: silicone-containing foam stabilizers, such as siloxane-oxalkylene copolymers and other organopolysiloxanes. Further alkoxylation of fatty alcohols, oxo alcohols, fatty amines, alkylphenols, dialkylphenols, alkylcresols, alkylresorcinol, naphthol, alkylnaphthol, naphthylamine, aniline, alkylaniline, toluidine, bisphenol A, alkylated bisphenol A, polyvinyl alcohol, and further alkoxylation of condensation products of formaldehyde and alkylphenols, formaldehyde and Dialkylphenols, formaldehyde and alkylcresols, formaldehyde and alkylresorcinol, formaldehyde and aniline, formaldehyde and toluidine, formaldehyde and naphthol, formaldehyde and alkylnaphthol and formaldehyde and bisphenol A. As the alkoxylation reagents, for example, ethylene oxide, propylene oxide, poly-THF and higher homologs can be used. As flame retardants, the flame retardants known from the prior art can generally be used. Suitable flame retardants are, for example, brominated ethers (Ixol), brominated alcohols such as Dibromneopentylakohol, Tribromneopentylalkohol and PHT-4-diol and chlorinated phosphates such. Example, tris (2-chloroethyl) phosphate, tris (2-chloroisopropyl) phosphate (TCPP), tris (1,3-dichloroisopropyl) phosphate, tris (2,3-dibromopropyl) phosphate and tetrakis (2- chloroethyl) ethylene diphosphate. In addition to the aforementioned halogen-substituted phosphates and inorganic flame retardants, such as red phosphorus, red phosphorus-containing finishes, alumina hydrate, antimony trioxide, arsenic oxide, ammonium polyphosphate and calcium sulfate or cyanuric acid derivatives such. As melamine or mixtures of at least two flame retardants, such as. For example, ammonium polyphosphates and melamine and, optionally, starch for flameproofing the PU rigid foams produced according to the invention can be used. Diethyl ethane phosphonate (DEEP), triethyl phosphate (TEP), dimethyl propyl phosphonate (DMPP), diphenyl cresyl phosphate (DPK) and others can be used as other liquid halogen-free flame retardants. The flame retardants are in the context of the present invention preferably in an amount of 0 to 65 wt .-%, particularly preferably from 10 to 65 wt .-%, in particular from 15 to 60 wt .-%, particularly preferably between 20 to 50 wt. %, based on the total weight of components (b) to (e) used.

Further details of the abovementioned and further starting materials can be found in the specialist literature, for example the Kunststoffhandbuch, Volume VII, Polyurethane, Carl Hanser Verlag Munich, Vienna, 1st, 2nd and 3rd editions 1966, 1983 and 1993.

To prepare the rigid polyurethane foams, the polyisocyanates (a) and the components (b) to optionally (e) are reacted in amounts such that the isocyanate index of the foam is 90 to 350, preferably 100 to 180, particularly preferably 110 to 140 is.

The rigid polyurethane foams can be prepared batchwise or continuously by known methods (eg double belt). The invention described herein relates to both methods, but preferably to the continuous double belt method.

It has proven to be particularly advantageous to work by the two-component process and the compounds (i) according to the invention with component (b) together with the blowing agents (c), the catalysts (d) and optionally the additives (e) to a so-called polyol component (also referred to herein above as the polyol component) and to bring these with the polyisocyanates or mixtures of the polyisocyanates and optionally blowing agents, also referred to as isocyanate component to implement. The polyol component without the blowing agent preferably has a viscosity greater than 1000 mPas. In a further preferred embodiment, the polyurethane foams have a bulk density of less than 80 g / l, particularly preferably less than 60 g / l. Furthermore, the polyurethane foams generally have a compressive strength according to DIN 53 421 of 0.1 N / mm ² or more, particularly preferably from 0.12 to 0.3 N / mm ² .

The rigid polyurethane foams according to the invention preferably have a closed cell content greater than 90%.

The use of the polyurethane rigid foams according to the invention is carried out in particular for thermal insulation, for example of refrigerators, containers or buildings, for. B. in the form of insulated pipes, boilers, sandwich panels, insulation boards or refrigerators. For the purposes of the present patent application, polyurethanes are also understood as meaning polymeric isocyanate adducts which, in addition to urethane groups, also contain further groups, such as are formed by reaction of the isocyanate group with itself, for example isocyanurate groups, or which are formed by reaction of the isocyanate groups with groups other than hydroxyl groups, the said groups usually being present together with the urethane groups in the polymer.

The invention will be illustrated by the following examples.

Examples

Basic recipe Foam production: A component 47.88 parts by weight a polyetherol (A) having an OHN of 435-465 mg KOH / g prepared by polyaddition of propylene oxide to a sucrose / glycerol mixture 30.00 parts by weight a polyetherol (B) having an OHN of 395-415 mg KOH / g prepared by polyaddition of propylene oxide and ethylene oxide to an aromatic amine 16.0 parts by weight a polyetherol (C) having an OHN of 155-165 mg KOH / g prepared by polyaddition of propylene oxide onto a 3-functional trimethylolpropane 1.9 parts by weight Stabilizer Tegostab ^® B 8462 1.02 parts by weight dimethylcyclohexylamine 0.5 parts by weight pentamethyldiethylenetriamine 0.4 parts by weight Tris (dimethylaminopropyl) hexahydrotriazine 2.3 parts by weight water Component B 37.5 parts by weight Polymer MDI with an NCO of 31% and a viscosity of 200 mPa s ^{25 ° C.}

The physical blowing agent used was 13 parts by weight of a mixture of 70% by weight of cyclopentane and 30% by weight of n-pentane.

• a) ohne Zusatz von Acrylat – Grundrezeptur

A ratio of 117 was used. A polyurethane foam was prepared by hand foaming from 100 parts by weight of A component and 127 parts by weight of B component. The reaction mixture is stirred with a disk stirrer Fa. Vollrath at a speed of 1500 ± 150 min ^-1 . At the beginning of stirring the stopwatch is started. For the thermal conductivity measurement was used a shape 20 cm × 20 cm × 20 cm with a compaction of 1.2. 1 cube for determining the compressive strength was annealed at 150 ° C for ½ h, for a post-reaction of unreacted monomeric acrylate. The normalized values of compressive strength were based on a bulk density of 28.7 g / l.

• a) without the addition of acrylate - basic formula

start time s 8th setting time s 52 density g / l 29.5 flow behavior cm 153 thermal conductivity mW / m 20.6 after 24 h 22.3 after 4 weeks Compressive strength N / mm ² 0.18 (normalized) 0.17 (normalized) annealed sample indentation test N 31.6 after 2 minutes 59.6 after 3 minutes 73.3 after 4 minutes 80.8 after 5 minutes

• b) Polyol C replaced by bisphenol A diglycidyl diacrylate in 20 wt .-% 1,6-hexanediol diacrylate

start time s 7 setting time s 49 density g / l 30.1 flow behavior cm 150 thermal conductivity mW / m 19.9 after 24 h 21.3 after 4 weeks Compressive strength N / mm ² 0.23 (normalized) * 0.22 (normalized) annealed sample indentation test N 34.3 after 2 minutes 61.1 after 3 minutes 68.9 after 4 minutes 73.6 after 5 minutes

• c) Polyol C replaced by 1,4-butanediol diglycidyl diacrylate

start time s 8th setting time s 47 density g / l 28.6 flow behavior cm 151 thermal conductivity mW / m 20.1 after 24 h 21.7 after 4 weeks Compressive strength N / mm ² 0.20 (normalized) 0.20 (normalized) annealed sample indentation test N 44.4 after 2 minutes 75.1 after 3 minutes 77.3 after 4 minutes 77.4 after 5 minutes

• d) polyol C replaced by bisphenol A diglycidyl diacrylate

start time s 7 setting time s 48 density g / l 28.6 flow behavior cm 152 thermal conductivity mW / m 19.9 after 24 h 21.4 after 4 weeks Compressive strength N / mm ² 0.20 (normalized) 0.20 (normalized) annealed sample indentation test N 34.8 after 2 minutes 65.3 after 3 minutes 74.5 after 4 minutes 78.0 after 5 minutes

All acrylates used improved the compressive strength. The best values were achieved with bisphenol A diglycidyl diacrylate in 20% by weight of 1,6-hexanediol diacrylate. All other parameters examined show no noteworthy changes to the basic formulation. Aftertreatment of the foams by tempering showed no significant additional improvement of the mechanical properties.

Claims (6)

Rigid polyurethane foam having a density between 20 kg / m ³ and 200 kg / m ³ , characterized in that the rigid polyurethane foam contains as compounds (i) one of the following compounds

Bisphenol A diglycidyl diacrylate and / or

1,4-Butandioldiglycidyldiacrylat, Polyurethane rigid foam according to claim 1, characterized in that the rigid foam is based on the reaction of isocyanates (a) with isocyanate-reactive compounds (b), being used as isocyanate-reactive compounds (b) polyether polyols having an equivalent weight of less than 400 g / mol exhibit. Polyurethane rigid foam according to claim 2, characterized in that the rigid foam is based on polymer MDI as isocyanate (a). A process for the production of rigid polyurethane foam having a density between 20 kg / m ³ and 200 kg / m ³ according to claims 1-3 by reacting (a) isocyanates with (b) compounds with isocyanate-reactive hydrogen atoms in the presence of (c) blowing agent and optionally catalysts (d), (e) additives, characterized in that one carries out the reaction in the presence of compounds (i), comprising the following compounds:

Bisphenol A diglycidyl diacrylate and / or

1,4-Butandioldiglycidyldiacrylat, A method according to claim 4, characterized in that is used as the isocyanate-reactive compounds (b) polyether polyols having an equivalent weight of less than 200 g / mol. A method according to claim 4, characterized in that is used as isocyanate (a) polymer MDI.