EP3504254A1

EP3504254A1 - Process for producing polymer foams comprising imide groups

Info

Publication number: EP3504254A1
Application number: EP17755161.1A
Authority: EP
Inventors: Anna Maria Mueller-Cristadoro; Frank Prissok
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2016-08-26
Filing date: 2017-08-18
Publication date: 2019-07-03
Also published as: US20190185611A1; CN109642007A; WO2018036921A1

Abstract

The present invention relates to a process for producing a polymer foam comprising reacting components A to C in the presence of component D and optionally E or of an isocyanate-functional prepolymer of components A and B with component C in the presence of component D and optionally E, the total amount of which is 100 wt%, (A) 35 to 75 wt% of at least one polyisocyanate component A, wherein 10 to 100 wt% of component A is a condensation product comprising polyimide groups and obtained by condensing at least one polyisocyanate component with at least one polycarboxylic acid having at least 3 COOH groups per molecule or anhydride thereof, (B) 5 to 50 wt% of at least one polyol component B, (C) 1 to 10 wt% of water as component C, and (D) 0.01 to 3 wt% of at least one Lewis base component D, (E) 0 to 5 wt% of at least one foam stabilizer component E, wherein said reacting is effected to release carbon dioxide.

Description

The present invention relates to a process for the preparation of a polymer foam containing imide groups, the polymer foam thus obtainable, the use of polyisocyanates containing imide groups for its preparation and its use.

Polymer foams, such as polyurethane and polyurethane-polyurea foams based on di- or polyisocyanates have long been known. Polyurethane hard phases have a much lower melting temperature compared to a polyamide hard phase, which has a decisive influence on the use of the materials at high temperatures.

Furthermore, the reaction of carboxylic acids with isocyanates to give mixed carbamic anhydrides and the partial further reaction to amides are known. The reaction and its mechanism are described, for example, by R.W. Hoffman in Synthesis 2001, no. 2, 243-246 and I. Scott in Tetrahedron Letters, Vol. 27, no. 1 1, pp 1251-1254, 1986.

Oligomeric compounds resulting from a reaction between a diisocyanate and a dicarboxylic acid are described by K. Onder in Rubber Chemistry and Technology, Vol. 59, pp. 615-622 and by T. O. Ahn in Polymer Vol. 2, pp. 459-456, 1998.

EP 0 527 613 A2 describes the preparation of foams containing amide groups. These are produced by means of organic polyisocyanates and polyfunctional organic acids. The foams are produced by means of an addition reaction in which an organic polyisocyanate reacts with the reaction product of a polyoxyalkylene and an organic polycarboxylic acid component. The two isocyanate groups react with a carbon dioxide generating compound. This compound is the reaction product of a polyoxyalkylene polyamine or a polyol component with an organic polycarboxylic acid component. The polyoxyalkylene polyamine or polyol component has an average molecular weight of 200 to 5000 g / mol. The starting temperature for the reaction is at least 150 ° C, the reaction time is in a range of half an hour to twelve hours. DE 42 02 758 A1 describes a foam with urethane and amide groups, which can be prepared using polyhydroxycarboxylic acids having a chain length of 8 to 200 carbon atoms. The polyhydroxycarboxylic acids are advantageously prepared by ring opening epoxidized unsaturated fatty acids with hydroxyl-containing compounds such as water, alcohol or hydroxycarboxylic acids. The bulk densities of the foams are in a range of 33 to 190 kg / m ³ . A disadvantage of the known polyurethane-polyamide foams is that the starting materials are either only reacted at relatively high temperatures, do not react completely with one another, or the foams have a foam density which does not correspond to standard polyurethane formulations.

WO 201 1/147723 describes materials which comprise at least one rubber and at least one polyimide, wherein the polyimide is a branched condensation product of at least one polyisocyanate having on average more than two isocyanate groups per molecule and at least one polycarboxylic acid having at least three carboxyl groups per molecule or its anhydride is. The polyimide is used to improve the attachment of polyurethanes to rubbers.

The object of the present invention is to provide polymer foams and processes for their preparation, wherein the polymer foams are dimensionally stable even at high temperatures in the presence of moisture and / or at high pressures, so that they are also used in the vicinity of engine, transmission or exhaust system can. In addition, the polymer foams should have advantageous properties with regard to long-lasting compressive strength, rigidity, elasticity, and compressive deformation forces. It is also an object to provide a polymer foam which has urea groups, wherein carbon dioxide is generated by a reaction of diisocyanate components with water, so that preferably no additional blowing agents are required. Due to the absence of additional blowing agents in the foams and advantages in burning the foams to be achieved, for example, a lower toxicity of the combustion gases or fire residues. The objects are achieved according to the invention by a process for producing a polymer foam comprising reacting components A to C in the presence of component D and optionally E or an isocyanate group-containing prepolymer of components A and B with component C in the presence of component D and optionally E, whose total amount is 100% by weight,

(A) 35 to 75% by weight of at least one polyisocyanate component A,

wherein 10 to 100 wt .-% of component A is a polyimide-containing condensation product of at least one polyisocyanate component with at least one polycarboxylic acid having at least 3 COOH groups per molecule or its anhydride, (B) 5 to 50 wt .-% of at least one Polyol component B,

(C) 1 to 10 wt .-% of water as component C and

(D) 0.01 to 3% by weight of at least one Lewis base component D,

(E) 0 to 5 wt .-% of at least one foam stabilizer component E, wherein the reaction takes place with liberation of carbon dioxide. In addition to the components A to D and optionally E, further ingredients may be present in the reaction mixture. The inventive method is characterized by the fact that forms by the reaction of water with an isocyanate a carbamic acid, which then forms an amine with C02 elimination. As a result of the CO 2 removal from the carbamic acid by means of Lewis bases as catalysts, the novel polymer foams can be obtained quickly and preferably without further addition of blowing agent. Urea groups form from the amine groups present in the reaction mixture and the isocyanate groups of component A, urethane groups form from the alcohol group-containing component B and the isocyanate groups of component A, resulting in polyureas and polyurethanes containing imide groups Have blocks.

The polymer foam may have different properties. For example, it may be a rigid foam or a soft foam. The polymer foam may preferably be a polymer foam. The present invention therefore preferably relates to the process according to the invention, wherein the polymer foam is a polymer hard foam. According to the invention, PIR foams may also be present.

For the purposes of the present invention, a polymer rigid foam can be understood to mean a volume change of the reaction mixture until the end of the reaction, even after the main reaction has ended, since the foam matrix is still viscous and the gas continues inside the foam can expand. In this case, the polymer foam may advantageously have cells or cavities within the polymer foam and also on the surface of the polymer foam.

The polymer rigid foams according to the invention may preferably have a compressive stress at 10% compression of greater than or equal to 80 kPa, preferably greater than or equal to 150 kPa, particularly preferably greater than or equal to 180 kPa.

Furthermore, the polymer rigid foam may preferably have a closed cell content of at least 30%, preferably greater than 60%, according to DIN ISO 4590. Further details on preferred inventive polymer foams can be found in "Kunststoffhandbuch, Volume 7, Polyurethanes", Carl Hanser Verlag, 3rd edition 1993, Chapter 6. For polyurethane foams, reference may also be made to DIN 7726.

The polymer foams according to the invention may preferably have a density of 10 to 250 kg / cm ³ , preferably 15 to 150 kg / cm ³ , particularly preferably 20 to 80 kg / cm ³ , in each case measured as the density of the core. Furthermore, the polymer foam according to the invention may preferably have a compressive strength of 0.05 to 0.25 N / mm ² , preferably 0.10 to 0.20 N / mm ² , according to DIN 53421 / DIN EN ISO 604. Furthermore, the polymer foam according to the invention may preferably have a compression of 2.0 to 10.0%, preferably 3.0 to 9.0%, according to DIN 53421 / DIN EN ISO 604. Furthermore, the polymer foam according to the invention may preferably have a TGA of 260 to 280 ° C., preferably 270 to 280 ° C., according to DIN ISO 1 1358. By using the Lewis base component according to the invention as accelerator, or catalyst in the reaction, it is possible to carry out the polyaddition and the polycondensation uniformly and at high speed, so that both the molecular weight buildup and the gelling of the resulting polymer as also the foaming, in particular by the released carbon dioxide, at the same time done in such a way that forms a stable uniform foam, which then solidifies. It has been found according to the invention that the use of a Lewis base component is sufficient for both partial reactions and the reactions are coordinated so that an increase in viscosity is associated simultaneously with the gas formation and foaming, which leads to a uniform formation of the foam. Otherwise, if the viscosity has already increased too much, foaming may be compromised. If, during foam formation, the viscosity increase is still too low, or has not used any gelling process, the resulting gas can rise through the liquid polymer and escape from it, or accumulate on the surface, so that a uniform foam structure is not formed. In the method according to the invention, these problems are overcome, and a polymer foam having a uniform cell distribution over the entire cross section of the polymer foam results.

Furthermore, it has been found according to the invention that, when using the amounts of the components according to the invention, the formation of carbon dioxide to produce a suitable polymer foam is sufficient, so that no external blowing agent has to be added. If a lesser density foam is desired, however, external physical blowing agents may also be included. For the purposes of the present invention, physical blowing agents are substances which evaporate under the conditions of polyurea 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, for example (cyclo) aliphatic hydrocarbons having 4 to 8 carbon atoms , or fluorohydrocarbons such as 1, 1, 1, 3,3-pentafluorobutane, for example Solkane ^® 365 mfc from Solvay Fluorides LLC.

However, preference is given to omitting the addition of external blowing agents. Likewise, according to the invention, an addition of polycarboxylic acids, apart from the polycarboxylic acid present in component A, is largely or completely avoided. Polycarboxylic acids other than the polycarboxylic acids present in component A are preferably not included in the reaction mixture.

In a preferred embodiment, the reaction mixture according to the invention thus contains 0 wt .-% of at least one polycarboxylic acid in addition to the polycarboxylic acid having at least 3 COOH groups per molecule or its anhydride in component A. By using a polyimide-containing condensation product of at least one polyisocyanate component with at least one polycarboxylic acid having at least three carboxyl groups per molecule or its anhydride as part or substitute of the polyisocyanate component A, it is possible to further improve the thermal stability of the foams formed.

The individual components used according to the invention are explained in more detail below. The polyisocyanate component A used according to the invention contains 10 to 100 wt .-%, preferably 50 to 100 wt .-%, in particular 70 to 100 wt .-%, of a polyimide-containing condensation product of at least one polyisocyanate component with at least one polycarboxylic acid having at least three Carboxyl groups per molecule or their anhydride as component A2, in addition to 0 to 90% by weight, preferably 0 to 50% by weight, in particular 0 to 30% by weight, of a polyisocyanate-containing polyimide group Component A1. In a particularly preferred embodiment, therefore, the polyisocyanate component A used according to the invention consists of a polyimide-containing condensation product of at least one polyisocyanate component with at least one polycarboxylic acid having at least three carboxyl groups per molecule or its anhydride (A2). In a further preferred embodiment, in addition to the condensation product of at least one polyisocyanate component with at least one polycarboxylic acid having at least three carboxyl groups per molecule or its anhydride, at least one further polyisocyanate is present in component A, for example in the abovementioned amounts. The polyisocyanate component A2 can be derived by reacting the polyisocyanate component A1 with at least one polycarboxylic acid having at least three carboxyl groups per molecule or its anhydride. Therefore, first the polyisocyanate component A1 is described and subsequently its reaction with polycarboxylic acids to the polyimide-containing polyisocyanate component A2.

For the purposes of the present invention, at least one polyisocyanate component, also referred to herein as component A1, polyfunctional aromatic and / or aliphatic isocyanates, eg. As diisocyanates are understood. Advantageously, the polyisocyanate component A1 can have a functionality with respect to isocyanate groups in a range from 1.8 to 5.0, particularly preferably a functionality of 1.9 to 3.5, and very particularly preferably a functionality of 2.0 to 3.0 exhibit.

Preferably, the suitable polyfunctional isocyanates contain on average 2 to at most 4 NCO groups. Suitable isocyanates are, for example, 1,5-naphthylene diisocyanate, xylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), diphenyldimethylmethane diisocyanate derivatives, di- and tetraalkyldiphenylmethane diisocyanate, 4,4-dibenzyl diisocyanate, 1, 3 Phenylene diisocyanate, 1,4-phenylene diisocyanate, the isomers of tolylene diisocyanate (TDI), optionally in a mixture, 1-methyl-2,4-diisocyanato-cyclohexane, 1,6-diisocyanato-2,2,4-trimethylhexane, 1, 6 Diisocyanato-2,4,4-trimethylhexane, 1-isocyanatomethyl-3-isocyanato-1,5,5-trimethylcyclohexane (IPDI), chlorinated and brominated diisocyanates, phosphorus-containing diisocyanates, 4,4-diisocyanatophenylperfluoroethane, tetramethoxybutane 1, 4-diisocyanate, butane-1,4-diisocyanate, hexane-1,6-diisocyanate (HDI), dicyclohexylmethane diisocyanate, cyclohexane-1,4-diisocyanate, ethylene diisocyanate, phthalic acid bis-isocyanatoethyl ester, and also polyisocyanates having reactive halogen atoms, such as 1 - Chloromethylphenyl-2,4-diisocyanate, 1-bromomethylphenyl-2,6-diisocyanate, 3,3-bis-chloromethyl ether-4,4'-diphenyl diisocyanate.

Other important diisocyanates are trimethylhexamethylene diisocyanate, 1,4-diisocyanatobutane, 1,12-diisocyanatododecane and dimer fatty acid diisocyanate.

Particularly suitable are 4,4-diphenylmethane diisocyanate (MDI), 2,4-diphenylmethane diisocyanate (MDI), hydrogenated MDI (H12MDI), polymeric methylenediphenyl diisocyanate, wherein the polymeric methylene diphenyl diisocyanate advantageously has a functionality of at least 2.2.

In a further embodiment of the process according to the invention, the component A1 has an average molecular weight in a range from 100 g / mol to 750 g / mol, advantageously an average molecular weight in a range from 130 g / mol to 500 g / mol and in particular a middle one Molecular weight in a range of 250 g / mol to 450 g / mol. To prepare the polyisocyanate component A2, the polyisocyanate component A1 may be subjected to a condensation reaction with at least one polycarboxylic acid having at least three carboxyl groups per molecule or its anhydride, resulting in a polyimide-containing condensation product. The polycarboxylic acid used for this purpose is also referred to as component A2b, while the polyisocyanate component A2a used can correspond to the polyisocyanate component A1.

As polycarboxylic acids A2b, aliphatic or preferably aromatic polycarboxylic acids are selected which have at least three COOH groups per molecule, or the respective anhydrides, preferably if they are present in low molecular weight, ie non-polymeric form. Such polycarboxylic acids having three COOH groups are also included, in which two carboxylic acid groups are present as the anhydride and the third as the free carboxylic acid.

In a preferred embodiment of the present invention, the polycarboxylic acid A2b used is a polycarboxylic acid having at least 4 COOH groups per molecule or the anhydride in question. Examples of polycarboxylic acids A2b and their anhydrides are 1,2,3-benzenetricarboxylic acid and

1 .2.3- Benzoltricarbonsäuredianhydrid, 1, 3,5-benzenetricarboxylic acid (trimesic acid), preferred

1 .2.4-Benzene tricarboxylic acid (trimellitic acid), trimellitic anhydride and in particular 1, 2,4,5-benzene tetracarboxylic acid (pyromellitic acid) and 1, 2,4,5-benzene tetracarboxylic dianhydride (pyromellitic dianhydride), 3,3 ', 4,4 "- Benzophenonetetracarboxylic acid, 3, 3 ', 4,4 "-

Benzophenonetetracarboxylic dianhydride, benzene hexacarboxylic acid (mellitic acid) and anhydrides of mellitic acid.

Also suitable are mellophanic acid and mellophanic anhydride, 1,2,3,4-benzenetetracarboxylic acid and 1,2,3,4-benzenetetracarboxylic dianhydride, 3,3,4,4-

Biphenyltetracarboxylic acid and 3,3,4,4-biphenyltetracarboxylic dianhydride, 2,2,3,3-biphenyltetracarboxylic acid and 2,2,3,3-biphenyltetracarboxylic dianhydride, 1, 4,5,8-naphthalenetetracarboxylic acid and 1, 4,5,8- Naphthalenetetracarboxylic dianhydride, 1, 2,4,5-naphthalenetetracarboxylic acid and 1, 2,4,5-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic acid and 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1, 4,5,8- Decahydronaphthalenetetracarboxylic acid and 1, 4,5,8-

Decahydronaphthalenetetracarboxylic dianhydride, 4,8-dimethyl, 1,2,3,5,6,7-hexahydronaphthalene 1, 2,5,6-tetracarboxylic acid and 4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene 1, 2,5,6-tetracarboxylic dianhydride, 2,6-dichloronaphthalene-1, 4,5,8-tetracarboxylic acid and 2,6-dichloronaphthalene-1, 4,5,8-tetracarboxylic dianhydride, 2,7-dichloronaphthalene-1, 4,5,8-tetracarboxylic acid and 2,7-dichloronahphthaline-1, 4,5,8-tetracarboxylic dianhydride, 2,3,6,7-tetrachloronaphthalene-1, 4,5,8-tetracarboxylic acid and 2,3,6, 7-Tetrachloronaphthalene-1, 4,5,8-tetracarboxylic dianhydride, 1, 3,9,10-phenanthrene tetracarboxylic acid and 1,3,9,10-phenanthrene tetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic acid and 3,4,9,10 Perylenetetracarboxylic dianhydride, bis (2,3-dicarboxyphenyl) methane and bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) methane and bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3,4- dicarboxyphenyl) methane and bis (3,4-dicarboxyphenyl) methane dianhydride, 1, 1 bis (2,3- dicarboxyphenyl) methane and 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,1-bis (3,4-dicarboxyphenyl) ethane and 1,1-bis (3,4-dicarboxyphenyl) ethane dianhydride, 1, 1 - Bis (3,4-dicarboxyphenyl) ethane and 1,1-bis (3,4-dicarboxyphenyl) ethane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propane and 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, 2,3-bis (3,4-dicarboxyphenyl) propane and 2,3-bis (3,4-dicarboxyphenyl) propane dianhydride, bis (3,4-carboxyphenyl) sulfone and bis (3,4-carboxyphenyl) sulfone dianhydride, Bis (3,4-carboxyphenyl) ether and bis (3,4-carboxyphenyl) ether dianhydride, ethylene tetracarboxylic acid and ethylene tetracarboxylic dianhydride, 1,2,3,4-

Butanetetracarboxylic acid and 1,2,3,4-butanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic acid and 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 2,3,4,5-pyrrolidinetetracarboxylic acid and 2,3,4,5-dibutylcarboxylic acid Pyrrolidine tetracarboxylic dianhydride, 2,3,5,6-pyrazine tetracarboxylic acid and 2,3,5,6-pyrazine tetracarboxylic dianhydride, 2,3,4,5-thiophenetetracarboxylic acid and 2,3,4,5-thiophenetetracarboxylic dianhydride.

According to the invention, preference is given to using 1, 2,4,5-benzenetetracarboxylic acid or its anhydride. In one embodiment of the present invention, anhydrides from US 2,155,687 or US 3,277,117 are used for the synthesis of component A2. If polyisocyanate A2a and polycarboxylic acid A2b are allowed to condense with one another, preferably in the presence of a catalyst, an imide group is formed with elimination of CO2 and H2O. If, instead of polycarboxylic acid A2b, the corresponding anhydride is employed, an imide group is formed with elimination of CO 2.

In this case, R ^{* is} the radical of polyisocyanate A2a which can not be further specified in the above reaction equation, and n is a number greater than or equal to 1, for example 1 in the case of a tricarboxylic acid or 2 in the case of a tetracarboxylic acid, where (HOOC) _n is an anhydride group of the formula C (= 0) -0-C (= 0) can be replaced.

In one embodiment of the present invention, polyisocyanate A2a is used in admixture with at least one diisocyanate, for example with tolylene diisocyanate, hexamethylene diisocyanate or with isophorone diisocyanate. In a particular variant, polyisocyanate A2a is used in admixture with the corresponding diisocyanate, for example trimeric HDI with hexamethylene diisocyanate or trimeric isophorone diisocyanate with isophorone diisocyanate or polymeric diphenylmethane diisocyanate (polymer MDI) with diphenylmethane diisocyanate.

In one embodiment of the present invention, polycarboxylic acid A2b is used in combination with at least one dicarboxylic acid or with at least one dicarboxylic acid anhydride, for example with phthalic acid or phthalic anhydride.

Components A2a and A2b are preferably used in a weight ratio of 20: 1 to 1: 1, particularly preferably 10: 1 to 2: 1, in particular 7: 1 to 3: 1. To carry out the synthesis process according to the invention, it is possible to use polyisocyanate (A2a) and polycarboxylic acid (A2b) or anhydride (A2b) preferably in an amount such that the molar fraction of NCO groups to COOH groups is in the range from 1: 3 to 3: 1 is preferably 1: 2 to 2: 1. An anhydride group of the formula CO-O-CO counts here like two COOH groups.

Component A2 preferably has a molecular weight Mw in the range from 1000 to 200,000 g / mol. Component A2 preferably has at least two imide groups per molecule, more preferably at least three imide groups per molecule.

Component A2 may be composed of structurally and molecularly uniform molecules, or of a mixture of molecularly structurally different molecules. Examples game, the polydispersity may Mw / M _n is at least 1, $ 4, for example 1, 4 to 50, preferably 1, 5 to 10. The polydispersity can be determined case by known methods, in particular by gel permeation chromatography (GPC). A suitable standard for this is, for example, polymethyl methacrylate (PMMA). In addition to the imide groups present in the polymer backbone, component A2 may have terminal or pendant functional groups which may be anhydride or acid groups as well as free or capped NCO groups.

Ideally, by means of this polyisocyanate component, a high density of imide bonds per polymer unit, which is produced in the inventive method can be achieved. As a result, preferably a hard phase with advantageous properties can be generated. Imides have higher melting points and higher decomposition temperatures than urethanes. Polymer hard foams having a higher proportion of imide bonds thus also have a higher melting point and a higher decomposition temperature and are therefore particularly suitable for high-temperature applications, for example as insulating materials in the engine compartment of a motor vehicle. By the presence of the imide bonds, the thermal stability can be further improved. Component A2 preferably has a number average molecular weight in the range from 1000 to 10,000 g / mol, more preferably from 2000 to 5,000 g / mol.

In the process of the invention, the reaction of 35-75 wt .-% of at least one polyisocyanate component A, preferably from 40 to 70 wt .-% of at least one polyisocyanate component A and particularly preferably from 60 to 70 wt .-% of at least one Polyisocyanate component A. In particular, the component A can be brought together, successively or in each case first with the respective components B, C and D and, if appropriate, E in contact. For example, components A and B can be used to produce an iso- reacted cyanate group-containing prepolymer. The prepolymer again has an isocyanate functionality of preferably from 2.5 to 3.

For the purposes of the present invention, at least one polyol component B, also referred to herein as component B, can be understood as meaning organic compounds which have at least two free hydroxyl groups. The compounds are preferably free of other functional groups or reactive groups, such as acid groups. Preferably, the polyol component B is a polyether polyol or polyester polyol. Examples of these are a polyoxyalkylene, a polyoxyalkenyl, a polyester diol, a polyester terol, a polyether glycol, in particular a polypropylene glycol, a polyethylene glycol, a polypropylene glycol, a polypropylene ethylene glycol, or mixtures thereof. By a mixture may be understood, for example, a copolymer, but also a mixture of polymers. The polyglycol component preferably has an average molecular weight of 200 g / mol to 6000 g / mol, in particular an average molecular weight of 250 g / mol to 3000 g / mol and particularly preferably an average molecular weight of 300 g / mol to 800 g / mol on.

The polyether polyols which can be used according to the invention are prepared by known processes. For example, they can be prepared by anionic polymerization with alkali metal hydroxides such. For example, sodium or potassium hydroxide or alkali metal such as. As sodium methylate, sodium or potassium ethylate or potassium isopropoxide as catalysts and with the addition of at least one starter molecule having 2 to 8, preferably 2 to 6, reactive hydrogen atoms, or by cationic polymerization with Lewis acids such as antimony pentachloride, boron fluoride etherate u. a., or bleaching earth can be prepared as catalysts. Likewise, polyether polyols can be prepared by Doppelmetallcyanidkatalyse from one or more alkylene oxides having 2 to 4 carbon atoms in the alkylene radical. Tertiary amines can also be used as catalyst, for example triethylamine, tributylamine, trimethylamine, dimethylethanolamine, imidazole or dimethylcyclohexylamine. For special applications and monofunctional starters can be incorporated into the Polyetherpolyolaufbau.

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: water, aliphatic and aromatic, optionally N-mono-, N, N- and Ν, Ν'-dialkyl-substituted diamines having 1 to 4 carbon atoms in the alkyl radical, such as optionally mono- and dialkyl-substituted ethylenediamine, diethylenetriamine , Triethylenetetramine, 1, 3-propylenediamine, 1, 3 or 1, 4-butylenediamine, 1, 2, 1, 3, 1, 4, 1, 5 and 1, 6-hexamethylenediamine, phenylenediamine, 2 , 3-, 2,4- and 2,6-toluenediamine (TDA) and 4,4'-, 2,4'- and 2,2'-diaminodiphenylmethane (MDA) and polymeric MDA. As starter molecules also come into consideration: alkanolamines, such as. For example, ethanolamine, N-methyl and N-ethyl ethanolamine, dialkanolamines such. As diethanolamine, N-methyl and N- Ethyldiethanolamin, trialkanolamines, such as. As triethanolamine, and ammonia. Preferably used are polyhydric alcohols, such as ethanediol, 1, 2- and 2,3-propanediol, diethylene glycol, dipropylene glycol, 1, 4-butanediol, 1, 6-hexanediol, glycerol, trimethylolpropane; Pentaerythritol, sorbitol and sucrose, and mixtures thereof. The polyether polyols may be used singly or in the form of mixtures.

Polyesterpolymers are e.g. prepared from alkanedicarboxylic acids and polyhydric alcohols, polythioether polyols, polyester amides, hydroxyl-containing polyacetals and / or hydroxyl-containing aliphatic polycarbonates, preferably in the presence of an esterification catalyst. Further possible polyols are given, for example, in "Kunststoffhandbuch, Volume 7, Polyurethanes", Carl Hanser Verlag, 3rd edition 1993, Chapter 3.1.

The polyester polyols preferably used may be prepared, for example, from dicarboxylic acids having 2 to 12 carbon atoms, preferably 4 to 6 carbon atoms, and polyhydric alcohols. As dicarboxylic acids are, for example, in

Consider: aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid and sebacic acid and aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid. The dicarboxylic acids can be used singly or as mixtures, e.g. in the form of an amber, glutaric and adipic acid mixture. For the preparation of the polyesterols, it may be advantageous to use, instead of the dicarboxylic acids, the corresponding dicarboxylic acid derivatives, such as dicarboxylic acid esters having 1 to 4 carbon atoms in the alcohol radical, dicarboxylic acid anhydrides or dicarboxylic acid chlorides. Examples of polyhydric alcohols are glycols having 2 to 10, preferably 2 to 6 carbon atoms, such as ethylene glycol, diethylene glycol, butanediol-1, 4, pentanediol-1, 5, hexanediol-1, 6, decanediol-1, 10, 2,2- Dimethylpropandiol-1, 3, propanediol-1, 3 and dipropylene glycol, triols having 3 to 6 carbon atoms, such as Glycerol and trimethylolpropane and higher-grade alcohol pentaerythritol. Depending on the desired properties, the polyhydric alcohols can be used alone or, if appropriate, in mixtures with one another. Preferably, the polyols used as component B polyether polyols or polyester polyols, particularly preferably polyether polyols are used. In a particularly preferred embodiment, component B consists of polyether polyols.

The polyether polyol used is preferably di- to tetrafunctional polyoxyalkylene oxide polyol having a hydroxyl number of 20 to 1000, preferably 100 to 900 and particularly preferably 300 to 450. Preferably, the average functionality is 2.5 to 3.5. The preferably used polyether polyol preferably has a content of secondary hydroxyl groups of greater than 70%, based on the total number of hydroxyl groups in the polyalkylene oxide polyol. The polyoxyalkylene oxide polyol preferably contains at least 50% by weight, particularly preferably at least 80% by weight, of propylene oxide, based on the content of alkylene oxide in the polyalkylene oxide polyol. In a further embodiment of the process according to the invention, the component B has an OH number of 10 mg KOH / g to 1000 mg KOH / g. In particular, component B may have an OH number of 30 mg KOH / g to 500 mg KOH / g.

Components A and (B + C) may be particularly preferred in a molar ratio of isocyanate groups of component A to isocyanate reactive groups such as hydroxyl or carboxylic acid groups of components B and C in the range of preferably 10: 1 to 1: 2 5: 1 to 1: 1, 5, in particular 3: 1 to 1: 1 are used.

The proportion of component B in the reaction mixtures may preferably be 15 to 40% by weight, in particular 25 to 35% by weight. As component C according to the invention 1 to 10 wt .-%, preferably 1, 0 to 5 wt .-% or 1, 2 to 5 wt .-%, particularly preferably 1, 0 to 2.5 wt .-% or 1, 3 to 2.5 wt .-%, most preferably 1, 4 to 2.0 wt .-%, water used. A particularly preferred upper limit for the amount of water is 2.5% by weight. According to the invention, for example, distilled or demineralized water can be used.

In the context of the present invention, at least one Lewis base component, here also referred to as component D, can be understood as meaning a compound which can make electron pairs available, as for example under the term "Lewis base" in chemistry Preferably, the lone pair of electrons is in an organic compound, but may also be attached to a metal or to an organometallic compound The Lewis base is preferably present in an amount of from 0.05 to 1% by weight, especially preferably 0.1 to 0.5 wt .-%, used.

In a preferred embodiment of the process according to the invention, the Lewis base component is selected from the group consisting of N-methylimidazole, melamine, guanidine, cyanuric acid, dicyandiamide or derivatives thereof. Ideally, the Lewis base can generate the formation of a carboxylate from the carboxylic acid so that it can react rapidly with the diisocyanate component. Likewise, the Lewis base also acts as a catalyst for the removal of CO2 in the reaction of the diisocyanate component with water. Particularly advantageous may be a synergistic effect of the formation of the carboxylate and the elimination of CO2 by means of the Lewis base result, so that only a catalyst or accelerator is necessary. In a further embodiment of the present invention, at least one PIR catalyst is added to the reaction mixture. This PIR catalyst catalyzes the reaction of three isocyanate groups in each case to form a polyisocyanurate (PIR) group, ie it is used if the formation of PIR groups is desired.

The at least one optional PIR catalyst may generally be any basic compound that can be incorporated into the reaction mixture. Preferably, the at least one, optionally present, PIR catalyst is selected from the group of basic alkali metal or alkaline earth metal compounds. The at least one optionally present PIR catalyst is particularly preferably selected from the group consisting of lithium hydroxide, lithium formate, lithium acetate, lithium propionate, lithium alcoholates, sodium hydroxide, sodium formate, sodium acetate, sodium propionate, sodium alcoholates, potassium hydroxide, potassium formate, potassium acetate, potassium propionate, potassium alcoholates, cesium hydroxide , Cesium formate, cesium acetate, cesium propionate, cesium alcoholates, ammonium hydroxide, ammonium formate, ammonium acetate, ammonium propionate, ammonium alcoholates and mixtures thereof. Corresponding alcoholates are derived, for example, from alcohols selected from the group consisting of methanol, ethanol, propanol, isopropanol, butanol, hexanol, heptanol, octanol and mixtures thereof, preferably selected from the group consisting of ethanol, propanol, isopropanol, hexanol, heptanol and mixtures from that.

In a preferred embodiment, the appropriate amount of the at least one PIR catalyst is taken up in a suitable solvent and / or suspending agent, for example a glycol, and added to the reaction mixture. The at least one PIR catalyst is generally used in an amount of from 0.1 to 5% by weight, preferably from 0.2 to 3% by weight, particularly preferably from 0.5 to 2% by weight, based in each case on Total amount of components present, before.

In a further embodiment of the process according to the invention, the reaction is carried out in the presence of at least one foam stabilizer as component E, the stabilizer E preferably comprising a siloxane copolymer. In this case, the polysiloxane copolymer is preferably selected from the group comprising polyether-polysiloxane copolymers, such as polyether-polydimethylsiloxane copolymers. The proportion of component E is 0 to 5 wt .-%, preferably 0 to 3 wt .-%, in particular 0 to 1 wt .-%. If the foam stabilizer component E is used, its proportion is preferably 0.1 to 5 wt .-%, particularly preferably 0.3 to 3 wt .-%, in particular 0.5 to 1, 5 wt .-%. The total amounts of the components A to E according to the invention always give 100 wt .-%. This means that in the reaction mixture, other, different from A to E, components may be present, but need not. If, apart from components A to E, there are other components before these amounts are added to the stated 100% by weight. The quantities of components A to E are normalized in terms of their sum

The process for producing a polymer foam may be carried out at a starting temperature in a range of at least 15 ° C to at most 100 ° C, more preferably at least 15 ° C to at most 80 ° C, especially at a starting temperature of at least 25 ° C to at most 75 ° C , and more preferably at a starting temperature of at least 30 ° C to at most 70 ° C are performed. In this case, the reaction of the above components can be carried out at atmospheric pressure. As a result, for example, the energy consumption during the production of the polymer foam can be reduced. Likewise, the disadvantageous influence of a higher temperature on the formation of a core combustion can be circumvented, and gas formation / foaming and viscosity increase are - as described above - well matched. In this case, the reactor and the reaction mixture are preferably heated to the appropriate temperature at which the reaction is started. In the course of implementation, the temperature may increase. Typically, the container in which the reaction takes place is not separately heated or cooled, so that the heat of reaction via the container walls or the air is discharged to the environment. Since the reaction is accelerated by means of the Lewis base component used in the process according to the invention, with the Lewis base acting as a catalyst, diisocyanate components and water can continue to react completely and quickly to an amine component with the process according to the invention. In this case, advantageously, the reaction does not have to be carried out at an elevated temperature, as described, for example, in EP 0 527 613 A2.

Within the scope of a preferred embodiment of the process according to the invention, the reaction to the polymer foam starts after at least 3 to 90 seconds, in particular after 5 to 70 seconds and most preferably after 5 to 40 seconds. In this case, starting the reaction means that the components A, B, C and D, after they have been brought into contact with one another, convert into the corresponding or the corresponding product (s). Advantageously, it does not need to be worked with externally heated components or reactors.

Another object of the present invention is a polymer foam, the polyisocyanates containing at least 10 wt .-%, preferably 100 wt .-%, polyimide-containing condensation products of at least one polyisocyanate with at least one polycarboxylic acid having at least 3 COOH Groups per molecule or its anhydride, polyols or an isocyanate group-containing prepolymer derived therefrom as monomers and water, in the polymer main chain urethane, imide and urea groups and preferably has a foam density of 10 kg / m ³ to 250 kg / m ³ Has. Another object of the invention is the use of polyisocyanates which are at least 10 wt .-%, preferably 100 wt .-%, polyimide-containing condensation products of at least one polyisocyanate with at least one polycarboxylic acid having at least 3 COOH groups per molecule or its anhydride , for the production of polymer foams.

For the purposes of the present invention, a polyaddition product is understood as meaning a chemical reaction product in which the starting materials react with each other, but no low molecular weight by-products, such as, for example, water or CO 2, for example. B. in urethane formation. For the purposes of the present invention, a polycondensation product may be understood as meaning a product which, in the reaction of two starting materials, yields at least one low molecular weight by-product, eg. As carbon dioxide in the amide formation.

Another object of the present invention is the use of the inventive polymer foam for thermal insulation or as a construction material.

For thermal insulation, the use is preferably carried out for the production of refrigerators or freezers, appliances for water heating or storage or of parts thereof, or for the thermal insulation of buildings, vehicles or equipment.

In this case, in particular in the above applications, the thermal barrier coating of the devices or devices, buildings or vehicles is formed by the polymer foam according to the invention. The entire housing or outer sheaths of the devices, buildings or vehicles can be formed by the polymer foam according to the invention.

As a construction material, the polymer foam according to the invention is preferably used as core foam for the production of sandwich composite materials. Such sandwich composite materials typically have a core of a polymer foam and a planking or shell made of wood, metal or preferably a glass fiber reinforced plastic. The plastic of the envelope or planking can be chosen freely. Often these are epoxy or polyester resins.

Such sandwich composite materials are preferably used in the automotive, shipbuilding, building or wind turbine industry.

According to the invention vehicles are understood to mean air, land or water vehicles, in particular aircraft, automobiles or ships.

Further applications of the polymer foams according to the invention are known to the person skilled in the art.

The following examples are intended to explain the invention in more detail: Examples:

In the following examples, the molecular weights were determined by gel permeation chromatography (GPC). The standard used was polymethylmethacrylate (PMMA). The solvent used was dimethylacetamide (DMAc). The NCO content was determined by NCO titration. The syntheses were carried out under nitrogen, unless stated otherwise.

Preparation of MDI Imide In a 4L 4-necked flask equipped with dropping funnel, reflux condenser, internal thermometer, and teflon tube, 100 g of 1, 2,4,5-benzenetetracarboxylic dianhydride (0.64 mol) dissolved in 1500 ml of acetone, and 0.1 g of water were added. Then 465 g of polymeric 4,4'-diphenylmethane diisocyanate (methylenediphenylene diisocyanate) having an average molecular weight of 337 g / mol and a functionality of 2.5 (ie 2.5 isocyanate groups per molecule) (1 , 38 mol) was added. While stirring, it was heated to 55 ° C and stirred for a further 6 hours at this temperature under reflux. It was then diluted by addition of 1000 g of polymeric 4,4'-diphenylmethane diisocyanate and heated with stirring to 55 ° C. The mixture was stirred for a further six hours at 55 ° C under reflux. Subsequently, the acetone was distilled off at normal pressure over a period of one hour. At the end of the distillation, the residue thus obtained was stripped with nitrogen at 70 ° C. and 200 mbar. An MDI-imide having an isocyanate functionality of

27% (measured via IR)

M _n = 3200 g / mol, M _w = 4850 g / mol

The resulting MDI-imide was used below to prepare the polymer foams.

Production of polymer foams

The following examples illustrate the preparation and the properties of the polyimide polyurethanes according to the invention. The materials according to the invention were produced in the laboratory with a stand mixer. To determine the physical properties, cubes were foamed with a volume of 20 I, which were then mechanically tested. The compositions of the starting materials are given in Table 1.

Table 1 Example 3 Example 4

Example 1 (See) Example 2 (See)

(inventive) (inventive)

Polyol 4.8 21, 1 28.8 33.5

MDI imide 90.1 75 67.9 63.5

Stabi 0.2 0.8 1, 1 1, 3

Lewis base 0.1 0.2 0.2 0.2

Propellant 4.8 2.9 2 1, 4

Where:

Polyol: Polypropylene glycol of average molecular weight (MW) of 420 g / mol

Propellant: water

MDI imide: polyimide based on benzene-tetracarboxylic dianhydride and polymers methylene diphenylene diisocyanate with a free isocyanate content of 27%

Stabi: polyether-polysiloxane copolymer

Lewis base: 1-methylimidazole

Example 1 (comparison)

The components according to Table 1 with the exception of the MDI imide were weighed in proportions to a total batch size of 2.5 parts and then homogenized. This mixture was stirred vigorously with 22.5 parts of MDI-imide with a laboratory stirrer. It formed no foam structure. No preparation of a testable foam pattern was possible.

Example 2 (comparison)

The components according to Table 1, with the exception of the MDI imide, were weighed in proportions to give a total batch size of 12.5 parts and then homogenized. This mixture was stirred vigorously with 37.5 parts of MDI-imide with a laboratory stirrer. It formed an unstable foam, which partially collapsed. No preparation of a testable foam pattern was possible.

Example 3 (according to the invention)

The components according to Table 1, with the exception of the MDI imide, were weighed in proportions to give a total batch size of 256.8 parts and then homogeneity. Siert. This mixture was stirred vigorously with 543.2 parts MDI-imide with a laboratory stirrer and then poured into the cube shape. In the mold, the foam rises and was left in it until it cures. Example 4 (according to the invention)

The components according to Table 1, with the exception of the MDI imide, were weighed in proportions to a total batch size of 200 parts and then homogenized. This mixture was stirred vigorously with 347.4 parts of MDI-imide with a laboratory stirrer and then poured into the cube shape. In the mold, the foam rises and was left in it until it cures.

Properties of the products obtained

Table 2

Density density core [kg / m ³ ]

Pressure-resistant. Compressive strength [N / mm ² ] according to DIN 53421 / DIN EN ISO 604

Compression upset [%] according to DIN 53421 / DIN EN ISO 604

Table 3

Density density core [kg / m ³ ]

Geschlossenz. Closed cell density [%] according to DIN ISO 4590

TGA Thermogravimetric analysis [° C] according to DIN EN ISO 1 1358, evaluation on

Absolute value basis at 95% of the starting mass

Claims

claims

1 . A process for producing a polymer foam, comprising reacting components A to C in the presence of component D and optionally E or an isocyanate group-containing prepolymer of components A and B with component C in the presence of component D and optionally E, the total amount thereof 100 Wt.%,

(A) 35 to 75% by weight of at least one polyisocyanate component A,

wherein 10 to 100% by weight of component A is a polyimide-containing condensation product of at least one polyisocyanate component with at least one polycarboxylic acid having at least 3 COOH groups per molecule or its anhydride,

(B) 5 to 50% by weight of at least one polyol component B,

(C) 1 to 10 wt .-% of water as component C and

(D) 0.01 to 3% by weight of at least one Lewis base component D,

(E) 0 to 5 wt .-% of at least one foam stabilizer component E, wherein the reaction takes place with liberation of carbon dioxide.

2. The method according to claim 1, characterized in that water is present as component C in an amount of 1, 3 to 2.5 wt .-%.

3. The method according to claim 1 or 2, characterized in that the polyol component B has an average molecular weight of 200 g / mol to 6000 g / mol.

4. The method according to any one of claims 1 to 3, characterized in that the polymer foam is a polymer foam.

5. The method according to any one of claims 1 to 4, characterized in that component B has an OH number of 10 mg KOH / g to 1000 mg KOH / g.

6. The method according to any one of claims 1 to 5, characterized in that the polymer foam has a foam density of 10 g / l to 250 g / l.

7. The method according to any one of claims 1 to 6, characterized in that the Lewis base component D is selected from N-methylimidazole, melamine, guanidine, cyanuric acid, dicyandiamide and their derivatives or mixtures thereof, in particular N-methylimidazole.

8. The method according to any one of claims 1 to 7, characterized in that the reaction takes place in the presence of a foam stabilizer component E, which comprises a Siloxancopo- lymer.

9. The method according to any one of claims 1 to 8, characterized in that the polyol component B is a polyether polyol or polyester polyol.

10. Polymer foam, obtainable by the process according to any one of claims 1 to 9.

1 1. Polymer foam derived from polyisocyanates which are at least 10% by weight, preferably 100% by weight, polyimide-containing condensation products of at least one polyisocyanate with at least one polycarboxylic acid having at least 3 COOH groups per molecule or its anhydride, polyols or a polyisocyanate Isocyanate group-containing prepolymer derived therefrom as monomers and water, in the polymer main chain urethane, imide and urea groups and preferably has a foam density of

10 kg / m ³ to 250 kg / m ³ has.

12. Use of polyisocyanates which are at least 10 wt .-%, preferably 100

% By weight, polyimide-containing condensation products of at least one polyisocyanate with at least one polycarboxylic acid having at least 3 COOH groups per molecule or its anhydride, for the production of polymer foams.

13. Use of the polymer foam according to claim 10 or 1 1 for thermal insulation or as a construction material.

14. Use according to claim 13 for the production of refrigerators or freezers, appliances for water heating or storage or parts thereof, or for the thermal insulation of buildings, vehicles or equipment.

15. Use according to claim 13 as core foam of sandwich composite materials.