WO2001000723A1

WO2001000723A1 - Polyisocyanate-polyaddition products

Info

Publication number: WO2001000723A1
Application number: PCT/EP2000/005493
Authority: WO
Inventors: Andreas Arlt; Dieter Rodewald; Martin Kreyenschmidt; Helmut Tesch
Original assignee: Basf Aktiengesellschaft
Priority date: 1999-06-23
Filing date: 2000-06-15
Publication date: 2001-01-04
Also published as: AU6263400A; DE19928687A1

Abstract

The invention relates to polyurethane flexible foams which have a density ranging from 15 to 300 kg/m3 and which contain lactones, lactams and/or cyclic esters.

Description

Polyisocyanate polyaddition

description

The invention relates to flexible polyurethane foams with a density of 15 to 300 kg / m ³ , preferably 2 to 70 kg / m3, containing lactones, lactams and / or cyclic esters and processes for their preparation. The invention further relates to the use of lactones, actams and / or cyclic esters for deactivating amine catalysts in polyisocyanate polyaddition products and / or for reducing the content of primary amines in polyisocyanate polyaddition products and / or for improving the mechanical properties in Polyisocyanate polyaddition products, especially the compression set, especially after damp heat aging.

The production of polyisocyanate polyaddition products by reacting polyisocyanates with isocyanate-reactive compounds in the presence of catalysts which accelerate the reaction of the isocyanate-reactive substances with isocyanates and, if appropriate, blowing agents, additives and / or auxiliaries is well known.

Like other plastics, polyisocyanate polyaddition products are subject to aging processes which generally lead to a deterioration in the properties of use over time. Significant aging influences are, for example, hydrolysis, photooxidation and thermal oxidation, which lead to bond breaks in the polymer chains. In the case of polyisocyanate polyaddition products, for example polyurethanes, hereinafter also referred to as PUR, the action of moisture and, in particular, the combination of moisture and increased temperature results in hydrolytic cleavage of the urethane and urea bonds.

This cleavage not only manifests itself in a significant deterioration in the properties of use, but also leads to the formation of primary aromatic amines, e.g. Toluylene diamine (TDA) and diaminodiphenyl methane (MDA) or primary aliphatic amines such as hexamethylene diamine or isophorone diamine.

As found in experiments, amine formation is affected by a number of parameters. In particular, high temperatures from 80 ° C in combination with high air humidity lead to hydrolytic splitting of the urethane and urea indices. Such conditions are important for some special areas of application of flexible PUR foams.

Another parameter that significantly influences the formation of primary amines is the type and amount of those used

Catalysts. As could be demonstrated in various experiments, the catalysts contained in polyurethane systems, which are necessary for the urethanization and blowing reaction, also catalyze the hydrolytic cleavage reaction to a considerable extent. The presence of catalysts is therefore a very important prerequisite for the hydrolysis of urethane and urine bonds. In addition, it could be shown that the efficiency of the hydrolysis depends to a large extent on the activity and type of the catalyst, and on the fact whether the catalyst remains in the system or can migrate out of the material. In particular, tertiary amine catalysts with reactive functional groups such as OH and H ₂ accelerate the amine formation considerably by lowering the activation energy for the cleavage reaction. The functional groups result in the incorporation of the catalysts into the resulting PUR network and the products produced therewith have the advantage of lower odor and fogging problems, since the catalysts cannot escape through diffusion after the completion of the PUR product. The same applies to formulations with polyols that were produced with primary or secondary amines as starting molecules and thus have catalytically active centers. Such polyols have been used increasingly recently. In the case of recipes with such constituents that are exposed to special moist and warm conditions as special applications, the formation of primary amines as fission products cannot be excluded. In the case of foams with amine catalysts which do not contain functional groups which can be incorporated, on the other hand, these generally escape shortly after completion or when the foam ages. With such foams, warm, humid conditions lead to significantly lower amine contents.

In order to reduce the hydrolytic cleavage of urethane and urea bonds, and thus the formation of primary amines, especially in such PUR products that are exposed to warm and humid conditions, it was necessary to find additives which deactivated the amine catalysts in their efficiency to hinder bond splitting. The additives should not significantly influence the foaming reaction. W096 / 23826 describes the preparation of rigid thermoplastic polyurethanes with improved melt strength by adding a deactivatable metal catalyst and adding a deactivator for the deactivatable metal catalyst in order to suppress the cleavage of urethane bonds. An improvement in the hydrolysis stability and thus the aging is not described. The catalysts mentioned are tin compounds which are deactivated via deactivators such as acids, especially based on phosphorus, antioxidant metal deactivators such as hindered phenolic polyamines, phenolic hydrazines or phenolic oximes. Deactivation of tertiary amine catalysts is not reported in this document. The deactivator is preferably used in an encapsulated form and must be produced in a complex technical process. The simple addition of additives to the isocyanate or polyol component would be desirable.

DE-A 42 32 420 discloses the use of β-unsaturated ester carboxylates for the production of polyurethane foams which have an improved compression hardness and elongation at break. Salts of α, β-unsaturated ester carboxylates are used herein as catalysts for the NCO / water reaction. In a subordinate clause it is described that the compounds are capable of adding amino groups which arise during slow foam aging due to the presence of olefinic double bonds in the vicinity of the carboxylate groups. A disadvantage of these compounds is their catalytic action, which leads to an impairment of the foaming reaction. However, the catalytic effect of additives to reduce the amine content in finished PUR foams is not desirable since, as described above, this leads to a further and accelerated formation of primary amines.

The use of lactones or cyclic esters and lactams as additives for reducing the content of primary aliphatic and aromatic amines and / or tertiary aliphatic amines in polyisocyanate polyaddition products, in particular flexible polyurethane foams, has not been described to date.

DE-A 197 10 978 describes lactones in combination with carbodimide-containing compounds as stabilizers against hydrolytic signs of aging in semi-hard, compact and / or cellular molded polyurethane parts. The addition of the active ingredient combinations of carbodiimide and lactone leads to a much lower one

Decrease in the tensile strength of the products after moist heat storage compared to a product without the addition of this combination. To- Part of these additives is that the lactones only act as hydrolysis stabilizers if they are used in combination with carbodimides, which have long been described as hydrolysis stabilizers for polyester urethanes. In addition, their effectiveness is only described in semi-hard polyurethanes.

GB 2193504 and US 4757095 disclose lactones and lactams as additives for prepolymers which are used for the production of microcellular polyurethane foams for shoe soles. The lactones and lactams bring about improved cold flexibility of the resulting elastomers, in that the freezing point of the prepolymers is lowered to 0 ° C. This patent does not deal with an improvement in long-term stability or the hydrolysis protection of the polyurethane elastomers. The same applies to US 4234445 and US 4195148, in which lactones are described as non-volatile additives for reducing the viscosity of polyurethane prepolymers for the production of sprayed polyurethanes. For the same purpose, caprolactone and cyclic carbonates are used in EP-A 276 452 for the production of rigid foams. In addition to the improved processability of the prepolymer, the polyurethane foams made from it have a number of other advantages such as improved dimensional stability and increased flame protection. However, the effectiveness is limited to prepolymers made from aromatic polyester polyols. This patent also does not deal with improved stability to hydrolysis or even a reduction in the amine content.

In WO 89/05830 i.a. Lactones are described as building blocks for the synthesis of polyester polyols, which are used in prepolymers for biodegradable, compact polyurethanes.

The object of the present invention was to deactivate amine catalysts in polyisocyanate polyaddition products, in particular after the preparation of the polyisocyanate polyaddition products, in particular in flexible polyurethane foams, and thus to prevent the formation of primary amines, in particular primary aromatic amines, in polyisocyanate polyaddition products. Additives should therefore be invented which are able to reduce the content of primary, preferably primary, aromatic amines, in particular in flexible PUR foams. In addition to their function as catalyst inhibitors, the additives should preferably also be capable of binding the aromatic amine formed in the polyurethane matrix. The additives should the foaming reaction in the production of polyurethane Do not negatively influence rigid or, in particular, flexible foams.

This problem was solved by the use of lactones, lactams and / or cyclic esters, hereinafter also referred to as "inhibitors", and in particular by the flexible polyurethane foams described at the outset. The inhibitors according to the invention are preferably already used in the generally known processes for the preparation of the polyisocyanate polyaddition products, preferably polyurethanes, which may have isocyanurate and / or urea structures, particularly preferably flexible polyurethane foams. The invention accordingly also relates to processes for the production of flexible polyurethane foams with a density of 15 to 300 kg / m ³ , preferably 20 to 70 kg / m3, the production being carried out in the presence of lactones, lactams and / or cyclic esters.

The addition of the inhibitors in PUR foam formulations surprisingly leads to significantly reduced levels of primary amines. Lactones or cyclic esters and lactams have accordingly been found as inhibitors according to the invention for reducing the content of primary amines in polyurethane products. Experiments have shown that there are various mechanisms that contribute to this reduction. The hydrolysis of lactones under the action of moisture to give hydroxycarboxylic acids is known from the literature. The carboxylic acid formed by hydrolysis of the inhibitors is capable of protonating the tertiary N atom in the amine catalyst. By blocking the catalytically active N atom with the formation of a quaternary N atom, the amine catalyst loses its catalytic activity with regard to the hydrolytic cleavage of urethane and urea bonds. This leads to a deterioration in the mechanical properties of the polyisocyanate polyaddition products, in particular the soft foams, in particular under warm and moist loads, and also in the formation of primary amines, in particular primary aromatic amines, for example 2,2 ^' -, 2,4' and / or 4, 4 ^' -MDA and / or 2,4- and / or 2,6-TDA counteracted. By adding the inhibitors, the hydrolysis of urethane and urea bonds is reduced in two ways, as mentioned by deactivating the amine catalysts present, but also by the fact that a large part of the penetrating water is already used for the hydrolysis of the lactones and lactams added and for the Cleavage of urethane and urea bonds is no longer available. On the other hand, however, the inhibitors are also capable of reacting with primary amine already formed to give hydroxy- or aminocarboxamides. By adding the inhibitors according to the invention, the diffusion or migration of primary amines from the polyurethane products can be reduced by converting the primary amines to hydroxy- or aminocarboxamides. Due to the higher molecular weight of the reaction products, in particular when using lactones of higher-membered carboxylic acids, such as hydroxydecanoic acid or hydroxydodecanoic acid, the diffusion or migration from the polyurethane matrix is reduced, so that the fogging behavior is improved.

After hydrolysis, lactams and lactones also improve the fogging behavior of polyurethane products by preventing the diffusion of the tertiary amine catalysts used by their protonation. Furthermore, in the case of polyurethane foams, in particular flexible polyurethane foams, it is desirable in some applications to increase the crosslinking density by adjusting the formulation (increasing the proportion of crosslinking agent, using multicore MDI, increasing the index), but without increasing the hardness too much. By adding lactones and lactams, which also act as plasticizers, it is possible to compensate for this undesirable increase in hardness.

The following compounds can be used as inhibitors according to the invention:

Lactones, e.g. those with a molecular weight of 70 to 300 g / mol, e.g. those of the following general formula:

with X: C2-C5-alkylene radical, which may optionally be branched and / or otherwise substituted.

Examples include: β-propiolactone, γ-butyrolactone, γ-valerolactone, ε-caprolactone, γ-decanolactone, δ-decanolactone, δ-dodecanolactone, γy-dimethylbutyrolactone and / or α-ethyl-γ-methylbutyrolactone.

Lactams, for example those with a molecular weight of 70 to 300 g / mol, for example those of the following general formula:

with X: C2-C5-al ylene residue, which may optionally be branched and / or otherwise substituted.

Examples include: β-propiolactam, 2-pyrrolidone, N-methylpyrrolidone and 2-piperidone.

Cyclic esters, for example those with a molecular weight of 150 to 500 g / mol, preferably condensation products of aliphatic, cycloaliphatic, araliphatic and / or aromatic dicarboxylic acids with 4 to 15 carbon atoms and aliphatic, cycloaliphatic, araliphatic and / or aromatic dialcohols 2 to 15 carbon atoms, particularly preferably condensation products based on diethylene glycol (DEG) and adipic acid (ADS). These cyclic esters, e.g. The cyclic DEG-ADS ester and the cyclic ADS-DEG-ADS-DEG ester are in addition to DEG and low molecular weight linear esters to about 40 - 50% by mass in a distillation residue which is involved in the synthesis of polyester polyols based on ADS -DEG-trimethylolpropane is obtained and is therefore particularly economical to use.

The inhibitors according to the invention are used for the production of polyisocyanate polyadducts by generally known processes, for example by reacting isocyanates with compounds which are reactive toward isocyanates in the presence of, if appropriate, catalysts, blowing agents, additives and / or auxiliaries. As polyisocyanate polyaddition products, for example, compact or cellular, for example microcellular, soft, semi-hard or hard polyurethane foams, thermoplastic polyurethanes or polyurethane elastomers can be produced by customary methods using the inhibitors according to the invention. The inhibitors according to the invention are preferably used in processes for the production of polyurethane elastomers or foamed polyisocyanate polyaddition products, in particular flexible polyurethane foams with a density of 15 to 300 kg / m ³ , preferably 2 to 70 kg / m3, preferably mattresses and / or upholstery for furniture or carpets, in particular hospital mattresses, by reacting isocyanates with compounds which are reactive toward isocyanates in Presence of catalysts, blowing agents and optionally additives and / or auxiliaries. These products, ie in particular the upholstery for furniture and / or carpets or the mattresses are increasingly being treated with hot steam for cleaning or disinfection, with which the advantages according to the invention are particularly pronounced in these products.

To prepare the polyisocyanate polyadducts, the inhibitors are preferably used in an amount of from 0.01 to 20.0% by weight, based on the weight of the compounds which are reactive toward isocyanates.

Cyclodextrins, resorcarenes, cyclophanes and / or cyclocalixarenes, for example with a molecular weight of 200 to 3000, preferably 200 to 1300 g / mol, hereinafter also referred to as "macrocycles", can preferably be used for the preparation of the polyisocyanate polyaddition products.

The use of macrocycles means that the macrocycles form complexes with tertiary amines, which were used as catalysts in the preparation of the polyisocyanate polyaddition products, in particular in the finished polyisocyanate polyaddition product, and the tertiary amines have their catalytic activity in the complex with the macrocycles can no longer unfold, ie are blocked. Since the complexed amine catalysts in the finished polyisocyanate polyaddition products are no longer capable of catalyzing the hydrolytic cleavage of urethane and urea bonds described at the outset, the macrocycles both worsen the mechanical properties, in particular under moist, warm conditions, and also the Formation of primary amines, especially primary aromatic amines, for example 2,2'-, 2,4 and / or 4,4 ^, -MDA and / or 2,4- and / or 2,6-TDA counteracted. Furthermore, the macrocycles according to the invention, by complexing with primary amines, for example primary aromatic amines, can prevent them from migrating or extracting from the polyisocyanate polyaddition product. The amine catalysts are also prevented from migration or extraction from the product by such complexation. The resulting reduced odor and fogging problems are particularly exacerbated by the fact that the additives according to the invention can preferably be at least partially incorporated into the polyurethane network by the presence of OH groups. The macrocycles thus fixed lead through inclusion of primary and / or tertiary amines for their immobilization in the foam matrix.

Macrocycles, e.g. In addition to amines, cyclodextrins are capable of including water molecules, which further reduces the occurrence of hydrolytic cleavage reactions and thus additionally counteracts the formation of primary amines.

Generally known compounds can be used as macrocycles, for example cyclodextrins, resorcarenes, cyclophanes and / or cyclocalixarenes, it being possible for the compounds mentioned in each case to be modified.

Cyclodextrins of this type, which may have a branched chain structure, are e.g. mentioned in US 5,063,251, column 2, lines 55 to 63 and DE-A 196 14 441, page 2, lines 46 to 47. Suitable cyclocalixarenes are described in US 4,642,362, column 2, line 34 to column 7, line 68th

Preferred is the use of α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, reaction products of these cyclodextrins with alkylene oxides, 4-tert-butylcalix [4] arene, 4-tert. -Butylcalix [6] arene, 4-tert-butylcalix [8] arene, 4-sulfocalix [4] arene, 4-sulfocalix [6] arene, 4-sulfocalix [8] arene, C-methylcalix [4] resorcinarene, C-undecylcalix [4] resorcinarene, tetra-N-pentylcalix [4] resorcinarene and / or [2.2] paracyclophane, particularly preferably ß-cyclodextrin, 4-tert-butylcalix [6] arene, 4-sulfocali [ 6] arenes and / or [2.2] paracyclophane.

The macrocycles can be used in the A and / or B component or in the constituents of these components, preferably in the isocyanate component, in order to avoid complexation of the amine catalysts which are usually contained in the A component before the polyurethane product is finished , If the macrocycles are neither soluble in the A nor in the B component, they are dispersed in the powdered form in one of the two components and then processed.

For the preparation of the polyisocyanate polyadducts, the macrocycles are preferably used in an amount of 0.2 to 5% by weight, based on the weight of the compounds which are reactive toward isocyanates.

Preference is furthermore given to salts of the metals of subgroup I, II and / or VIII, hereinafter also generally referred to as metal salts, for the preparation of the polyisocyanate-polyadditive on products used. The term "salts of metals" or "metal salts" also includes the cations of the metals according to the invention in complex form and is therefore the subject of the technical teaching.

Due to the use of the metal salts, it is achieved that the metal ions form complexes with tertiary amines, which are used as catalysts in the preparation of the polyisocyanate polyadducts, and the tertiary amines can no longer develop their catalytic activity in the complex with the metals, ie are blocked , Since the complexed amine catalysts in the finished polyisocyanate polyaddition products are no longer capable of catalyzing the hydrolytic cleavage of urethane and urea bonds described at the outset, the metal salts cause both a deterioration in the mechanical properties, in particular under hot and humid stress, and the formation of primary ones Amines, in particular primary aromatic amines, for example 2,2 ^' -, 2,4' and / or 4, 4 ^' -MDA and / or 2,4- and / or 2,6-TDA counteracted. Furthermore, the metal salts according to the invention can by

Complexation with primary amines, for example primary aromatic amines, prevent them from migrating or being extracted from the polyisocyanate polyaddition product. The aminic catalysts are also prevented from migrating or extracting from the product by such complexation, which manifests itself in an improved fogging behavior of the foams. In addition, the metal salts can act as oxidation catalysts and accelerate the oxidative degradation of aromatic amines that may be formed.

Well-known salts of the metals, for example salts of inorganic and / or organic acids, e.g. Mineral acids, the subgroups shown are used, for example salts of the following metals: Cu, Ni, Co, Fe, Zn, Ag, Pd, and Rh, preferably Cu, Ni and / or

Fe salts, where the metals can have any stable oxidation state.

As an anion in the metal salts, generally customary anions can be present, for example chloride, sulfate, nitrate and / or

Carboxylates with 1 to 20 carbon atoms. Furthermore, salts of complexed cations of the same metals with known ligands such as monoalkylamines, alkylenediamines, phenantroline, acetylacetone, aromatic phosphines such as triphenylphosphine, aliphatic phosphines such as tributylphosphine, salicylaldehyde and / or 1,4-diazabutadiene derivatives are used, preferably no tertiary amines as ligands be used. For example the following compounds are suitable as metal salts or their complexed cations: Cu (II) sulfate, Cu (II) chloride, Ni (II) sulfate, Co (II) chloride, Cu (II) naphtenate, Fe ( II) chloride, Cu (I) chloride, Fe (III) chloride, Cu (II) acetate-ethylenediamine complex, Fe (II) -phenantroline complex (commonly known as a redox indicator under the term ferroin), Cu (I ) -nitratobistriphenyl-phosphine complex, [glyoxal-bis (cyclohexylimine)] chloro-copper (I) complex.

The central atom and ligand of the metal-ligand complex should preferably be chosen so that the central atom of the complex can form complexes with primary aromatic amines or tertiary aliphatic amines or catalyze their oxidation. The complex between MDA and / or TDA or the amine catalysts and the metal cation of the complexes used is preferably more stable, i.e. the dissociation constant is larger than is the case for the complex cation used.

Cu (II) sulfate, Ni (II) sulfate, Cu (II) acetate, Fe (II) -phenantroline complex, Cu (II) acetate-ethylenediamine complex, Cu (II) naphtenate and / or Cu ( I) -nitratobistriphenylphosphane complex used as the metal salt.

To produce the polyisocyanate polyaddition products, the metal salts are preferably used in an amount of 0.05 to 5% by weight, based on the weight of the sum of the metal salts and the compounds which are reactive toward isocyanates.

The metal salts can be used in the A and / or B component or in the components of these components, preferably in the isocyanate component.

In addition, organic and / or inorganic acid anhydrides, particularly preferably at least one carboxylic acid anhydride, can preferably be used to prepare the polyisocyanate polyadducts, the acid anhydride (s) preferably in an amount of from 0.01 to 20% by weight, based on the Weight of the isocyanates and the acid anhydrides, is used.

Because of the acid anhydrides it is achieved that the anhydrides in the polyisocyanate polyadducts are hydrolyzed to the acids, especially under moist and warm conditions. These acids formed after the hydrolysis block the aminic catalysts which may be present in the products, for example by protonation or reaction, and thus prevent the cleavage of the urethane bonds from being accelerated. In addition, an undesirable split Free amino groups possibly formed by urethane bonds are bound by reaction with the acid anhydrides according to the invention.

The acid anhydrides are thus used in polyisocyanate polyaddition products to stabilize the polyisocyanate polyaddition products, in particular polyurethanes, against cleavage of the urethane and urea bonds, for example by blocking amine catalysts by protonation of the catalysts or by reaction with the catalysts. In addition, the acid anhydrides in polyisocyanate polyadducts for reaction with amino groups, for example to form amides, can be used in the polyisocyanate polyadducts.

The diffusion of amines from the polyisocyanate polyaddition products and the cleavage of the urethane bond, for example by amine catalysts present in the polyisocyanate polyaddition products, can thus be reduced.

It has surprisingly been found that acid anhydrides which are used in the production of polyisocyanate polyaddition products survive the production process almost undamaged and do not significantly interfere in the reaction. This applies in particular if the acid anhydrides are used in a mixture with isocyanates, since this component is usually free of water and thus hydrolysis of the anhydrides can be avoided. The use of the acid anhydrides in a mixture with compounds which are reactive toward isocyanates can particularly preferably be carried out in such a way that the acid anhydrides are only added to this mixture shortly before the polyisocyanate polyaddition products are prepared, since the compounds which are reactive toward isocyanates usually contain small amounts of water, with also the acid anhydrides according to the invention can be stable over a longer period in the compounds reactive toward isocyanates.

Surprisingly, it was found that the acid anhydrides mixed with isocyanates at room temperature, i.e. 25 ° C are stable and the isocyanate groups do not react or do not react significantly with the anhydride groups.

Organic or inorganic acid anhydrides, for example also polyanhydrides, can be used as anhydrides, preferably carboxylic acid anhydrides, for example anhydrides of aliphatic, cycloaliphatic, araliphatic and / or aromatic carboxylic acids with usually 1 to 10, preferably 1 to 2, carboxyl groups, with mixed anhydrides also being prepared on the base of at least two different carboxylic acids can be used. Polyanhydrides obtainable by di- and / or polycarboxylic acids or copolymers of anhydrides and various alkenes can also be used as anhydrides. The carboxyl groups of the compounds are preferably largely, particularly preferably completely, converted into the corresponding anhydrides. The compounds (ii) usually have a molecular weight of 60 to 1,000,000. Examples include: acetic anhydride, propionic anhydride, butyric anhydride, pentanoic anhydride, hexanoic anhydride, heptanoic anhydride, octanoic anhydride, dirnethylol propionic anhydride, adipic anhydride, fumaric anhydride, 4,4'-mesacrylic anhydride, ethylenedimide anhydride, 4-methylene malonic anhydride, bismethylene anhydride, 4-methylene malonide anhydride '- (2-acetyl-l, 3-glycerol) - bis-anhydrotrimellithate, decanedioic anhydride, dodecanedioic acid anhydride, azelaic acid anhydride, pimelic acid anhydride, brassylic acid anhydride, citraconic acid anhydride, itaconic acid anhydride, naphthalene dicarbonic acid, 1-8-diacid anhydride acid anhydride, chlorendic acid anhydride, 1,2,3, 6-tetrahydrophthalic acid anhydride, mellophanoic acid anhydride, benzene-1, 2, 3, 4-tetra-carboxylic acid anhydride, benzene-1, 2, 3-tricarboxylic acid anhydride, benzoic acid anhydride, diphenyl-3, 3 ' -4, 4 'tetracarboxylic anhydride, diphenyl-2, 2' -3, 3 'tetracarboxylic acid drid, naphthalene-2, 3,6,7-tetracarboxylic anhydride, naphthalene-1, 2, 4, 5-tetracarboxylic acid anhydride, naphthalene-1, 4, 5, 8-tetracarboxylic anhydride, decahydronaphthalene-1, 4,5, 8- tetracarboxylic anhydride, 4, 8-dimethyl-l, 2,3,5,6, 7-hexahydronaphthalene-1, 2,5, 6-tetracarboxylic acid anhydride, 2, 6-dichloronaphthalene-l, 4,5, 8-tetracarbonate anhydride , 2, 7-dichloronaphthalene-l, 4,5, 8-tetracarbonic acid anhydride, 2,3,6, 7-tetrachloronaphthalene-l, 4,5, 8-tetracarbonic acid anhydride, phenanthrene-1, 3,9, 10 -tetracarboxylic anhydride, perylene-3, 4,9, 10-tetracarboxylic anhydride, bis (2, 3-dicarboxyphenyl) methane anhydride, bis (3, 4-dicarboxyphenyl) methane anhydride, 1, 1-bis (2, 3-dicarboxyphenyl) ethane anhydride , 1, 1-bis (3, 4-dicarboxyphenyl) ethane anhydride, 2, 2-bis (2, 3-dicarboxyphenyl) propane anhydride, 2, 2-bis (3, 4-dicarboxyphenyl) propane anhydride, bis (3, 4 -dicarboxy-phenyl) sulfonic anhydride, bis (3, 4-dicarboxyphenyl) ether anhydride, ethylene tetracarboxylic anhydride, Bu tan-1, 2,3, 4-tetracarboxylic acid anhydride, cyclopentane-1, 2,3, 4-tetracarboxylic acid anhydride, pyrrolidine-2, 3, 4, 5-tetracarboxylic acid anhydride, pyrazine-2, 3, 5, 6-tetracarboxylic acid anhydride, Mellitic anhydride, thiophene-2, 3, 4, 5-tetracarboxylic acid anhydride, benzophenone-3, 3 ', 4, 4' -tetracarboxylic acid anhydride, maleic anhydride, glutaric anhydride, pyromellitic anhydride, phthalic anhydride, isophthalic acid, and / or terephthalic acid, / terephosphonic anhydride, , Malonic anhydride, succinic anhydride, poly-maleic anhydride, Anhydrides based on adducts of maleic acid with styrene, dodecenylsuccinic anhydride, anhydrides from maleic acid and any alkylenes, such as n-octylene-succinic anhydride, n-dodicylenesuccinic anhydride and / or copolymers from anhydrides and any other monomers, such as isobutene and maleic acid, maleic (ethylene-co-acrylic acid butyl ester comaleic acid dianhydride) and / or poly- (styrene-co-maleic acid anhydride), the corresponding di- or polyacids being partially or preferably completely present as anhydrides. The corresponding anhydrides of the di- or polyacids can, as far as this is sterically possible, be designed to be both inter- and intramolecular.

Anhydrides based on the following compounds are preferably used: pyromellitic acid, succinic acid, maleic acid, polymaleic anhydride, glutaric acid, which can also contain very different side groups, and / or copolymers of these anhydrides with all conceivable monomers which can be polymerized with anhydrides or acids.

Anhydrides which dissolve well in the isocyanates and / or the compounds which are reactive toward isocyanates, preferably the isocyanates, are generally particularly preferred.

The other starting materials for the production of the polyisocyanate polyaddition products are described below by way of example.

The known aliphatic, cycloaliphatic, araliphatic and preferably aromatic organic isocyanates, preferably polyfunctional, particularly preferably diisocyanates, can be used as isocyanates.

The following may be mentioned by way of example: alkylene diisocyanates having 4 to 12 carbon atoms in the alkylene radical, such as 1, 12-dodecane diisocyanate, 2-ethyl-tetramethylene diisocyanate-1, 4, 2-methylpenta- methylene diisocyanate-1, 5, tetramethylene diisocyanate-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, l-isocyanato-3, 3, 5-trimethyl-5-isocyanatomethyl-cyclohexane (isophorone diisocyanate), 2,4- and 2, 6-hexahydrotoluene diisocyanate and the corresponding isomer mixtures, 4,4'-, 2,2'- and 2, 4 '-dicyclohexylmethane diisocyanate and the corresponding isomer mixtures, aromatic di- and polyisocyanates, such as 2,4- and 2, 6-tolylene diisocyanate (TDI) and the corresponding isomer mixtures, 4,4'-, 2,4'- and 2, 2'-diphenylmethane diisocyanate (MDI) and the corresponding Mixtures of isomers, naphthalene-1,5-diisocyanate (NDI), mixtures of 4,4'- and 2,4'-diphenylmethane diisocyanates, mixtures of NDI and 4,4'- and / or 2,4'-diphenylmethane diisocyanates .

3, 3 '-dimethyl-4, 4' -diisocyanatodiphenyl (TODI), mixtures of TODI and 4,4'- and / or 2,4 '-diphenylmethane diisocyanates, polyphenyl polymethylene polyisocyanates, mixtures of 4, 4'-, 2,4'- and 2,2'-diphenylmethane diisocyanates and polyphenylpolymethylene polyisocyanates (crude MDI) and mixtures of crude MDI and Toluylene diisocyanates. The organic di- and polyisocyanates can be used individually or in the form of their mixtures.

So-called modified polyvalent isocyanates, i.e. Products obtained by chemical reaction of organic di- and / or polyisocyanates are used. Examples include di- and / or polyisocyanates containing ester, urea, biuret, allophanate, carbodiimide, isocyanurate, uretdione and / or urethane groups. In particular, the following may be considered, for example: Organic, preferably aromatic polyisocyanates containing urethane groups with NCO contents of 33.6 to 15% by weight, preferably 31 to 21% by weight, based on the total weight, of modified 4,4 '-Diphenylmethane diisocyanate, modified 4,4'- and 2,4'-diphenylmethane-diisocyanate mixtures, modified NDI, modified TODI, modified crude MDI and / or 2,4- or 2,6-tolylene diisocyanate The following may be mentioned as di- or polyoxyalkylene glycols, which can be used individually or as mixtures, for example: diethylene, dipropylene glycol, polyoxyethylene, polyoxypropylene and polyoxypropylene-polyoxyethylene glycols, triols and / or tetrols. Prepolymers containing NCO groups and having NCO contents of 25 to 3.5% by weight, preferably 21 to 14% by weight, based on the total weight, made of, for example, polyester and / or preferably polyether polyols and 4, are also suitable , 4'-diphenylmethane diisocyanate, mixtures of 2,4'- and

4,4 'diphenylmethane diisocyanate, NDI, TODI, mixtures of NDI and isomers of MDI, 2,4- and / or 2,6-tolylene diisocyanates or crude MDI. Liquid polyisocyanates containing carbodiimide groups and / or isocyanurate rings with NCO contents of 33.6 to 15, preferably 31 to 21% by weight, based on the total weight, e.g. based on 4,4'-, 2,4'- and / or 2,2'-diphenylmethane diisocyanate, NDI, TODI and / or 2,4- and / or 2,6-tolylene diisocyanate.

The modified polyisocyanates can be combined with one another or with unmodified organic polyisocyanates such as, for example, 2,4'-, 4,4'-diphenylmethane diisocyanate, NDI, TODI, crude MDI, 2,4- and / or 2,6-tolylene diisocyanate may be mixed. 4,4'-, 2,4'- and / or 2,2'-diphenylmethane diisocyanate, 2,4- and / or 2,6-tolylene diisocyanate, NDI, hexamethylene diisocyanate are preferred as isocyanates in the mixtures or processes according to the invention and / or isophorone diisocyanate are used, these isocyanates being usable either in any mixtures or modified as already described.

As isocyanate-reactive compounds with usually at least two reactive hydrogen atoms, usually hydroxyl and / or amino groups, it is advantageous to use those with a functionality of 2 to 8, preferably 2 to 6, and a molecular weight of usually 60 to 10,000. Have proven successful Polyether polyamines and / or preferably polyols selected from the group of polyether polyols, polyester polyols, polythioether polyols, polyester amides, hydroxyl group-containing polyacetals and hydroxyl group-containing aliphatic polycarbonates or mixtures of at least two of the polyols mentioned. Polyester polyols and / or polyether polyols, which can be prepared by known processes, are preferably used.

The polyester polyols preferably have a functionality of 2 to 4, in particular 2 to 3, and a molecular weight of usually 500 to 3000, preferably 1200 to 3000 and in particular 1800 to 2500.

The polyether polyols have a functionality of preferably 2 to 6 and usually molecular weights of 500 to 8000.

Also suitable as polyether polyols are, for example, polymer-modified polyether polyols, preferably graft polyether polyols, in particular those based on styrene and / or acrylonitrile, which are prepared by in situ polymerization of acrylonitrile, styrene or preferably mixtures of styrene and acrylonitrile can.

Like the polyester polyols, the polyether polyols can be used individually or in the form of mixtures. They can also be mixed with the graft polyether polyols or polyester polyols and hydroxyl-containing polyester amides, polyacetals and / or polycarbonates.

In particular, highly functional polyols, in particular polyether polyols based on highly functional alcohols, are sugar alcohols for rigid polyurethane foam materials which may have isocyanurate structures and / or saccharides as starter molecules, for flexible foams, in particular 2- and / or 3-functional polyether and / or polyester polyols based on glycerol and / or trimethylolpropane and / or glycols as starter molecules or alcohols to be esterified. The polyether polyols are produced using a known technology. Suitable alkylene oxides for the preparation of the polyols 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. Alkylene oxides which lead to primary hydroxyl groups in the polyol are preferably used. Particularly preferred polyols are those which have been alkoxylated with ethylene oxide at the end of the alkoxylation and thus have primary hydroxyl groups. For the production of thermoplastic polyurethanes it is preferred to use polyols with a functionality of 2 to 2.2 and no crosslinking agents.

Further chain extenders and / or crosslinking agents can be used as compounds reactive toward isocyanates. For example to modify the mechanical properties of the polyisocyanate polyaddition products made with these substances, e.g. the hardness, the addition of chain extenders, crosslinking agents or, if appropriate, mixtures thereof can prove to be advantageous. Water, diols and / or triols with molecular weights from 60 to <500, preferably from 60 to 300, can be used as chain extenders and / or crosslinking agents. For example, aliphatic, cycloaliphatic and / or araliphatic diols with 2 to 14, preferably 4 to 10 carbon atoms, such as e.g. Ethylene glycol, propanediol-1, 3, decanediol-1,10, o-, m-, p-dihydroxycyclohexane, diethylene glycol, dipropylene glycol and preferably butanediol-1, 4, hexanediol-1, 6 and bis- (2-hydroxy- ethyl) -hydroquinone, triols, such as 1,2,4-, 1, 3, 5-trihydroxy-cyclohexane, glycerol and trimethylolpropane and low molecular weight hydroxyl-containing polyalkylene oxides based on ethylene and / or 1, 2-propylene oxide and diols and / or triols as starter molecules.

If chain extenders, crosslinking agents or mixtures thereof are used to prepare the polyisocyanate polyaddition products, these are advantageously used in an amount of 0 to 20% by weight, preferably 2 to 8% by weight, based on the weight of the isocyanates-reactive Compounds are used, thermoplastic polyurethanes preferably being produced without crosslinking agents. Suitable catalysts are generally customary compounds, for example organic amines, for example triethylamine, triethylenediamine, tributylamine, dirnethylbenzylamine, N, N, N ', N'-tetramethylethylenediamine, N, N, N', N'-tetramethylbutane diamine, N, N, N ', N'-tetramethyl-hexane-l, 6-diamine, dimethylcyclohexylamine, pentamethyldipropylenetriamine, pentamethyldiethylenetriamine, 3-methyl-6-dimethylamino-3-azapentol, dirnethylaminopropylamine, 1, 3-bisdimethylaminobutane, bis- (2-dimethylaminoethyl) ether, N-ethylmorpholine, N-methylmorpholine, N-cyclohexylmorpholine, 2-dimethylaminoethoxyethanol, dimethylethanolamine, tetramethylhexamethylenediamine, dirnethylamino-N-methylethanolamine, N-methylimidazole, N- (3-aminopropyl) imidazole, N- (3-aminopropyl) -2-methylimidazole, 1- (2-hydroxyethyl) imidazole, N-formyl-N, N'-dimethylbutylene diamine, N -Dimethylaminoethylmorpholine, 3, 3 '-Bis-dimethylamino-di-n-propylamine and / or 2, 2' -Dipiparazin- diisopropylether, Dirnethylpiparaz in, N, N'-bis (3-aminopropyl) ethylenediamine and / or tris- (N, N-dimethylaminopropyl) -s-hexahydrotriazine, or mixtures containing at least two of the amines mentioned, high-molecular tertiary amines also being used, as described for example in DE-A 28 12 256, are possible. Furthermore, conventional organic metal compounds can be used as catalysts for this purpose, preferably organic tin compounds, such as tin (II) salts of organic carboxylic acids, for example tin (II) acetate, tin (II) octoate, tin ( II) ethylhexoate and tin (II) laurate and the dialkyltin (IV) salts of organic carboxylic acids, for example dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate and dioctyltin diacetate. Tertiary aliphatic and / or cycloaliphatic amines can preferably be contained in the mixtures in the mixtures, particularly preferably triethylenediamine.

As blowing agents, optionally, preferably for the production of foamed polyurethanes, generally known blowing agents, such as, for example, substances which have a boiling point under normal pressure in the range from -40 ° C. to 120 ° C., gases and / or solid blowing agents and / or water in customary manner Amounts are used, for example carbon dioxide, alkanes and or cycloalkanes such as isobutane, propane, n- or iso-butane, n-pentane and cyclopentane, ethers such as diethyl ether, methyl isobutyl ether and dimethyl ether, nitrogen, oxygen, helium, argon, laughing gas , halogenated hydrocarbons and / or partially halogenated hydrocarbons such as trifluoromethane, monochlorotrifluoroethane, difluoroethane, pentafluoroethane, tetrafluoroethane or mixtures which contain at least two of the blowing agents mentioned by way of example. Examples of auxiliaries and / or additives are surface-active substances, foam stabilizers, cell regulators, fillers, dyes, pigments, flame retardants, hydrolysis protection agents, fungistatic and bacteriostatic substances.

Usually, the organic polyisocyanates and the isocyanate-reactive compounds with a molecular weight of 60 to 10000 g / mol are reacted in such amounts that the equivalence ratio of NCO groups of the polyisocyanates to the sum of the reactive hydrogen atoms of the isocyanate-reactive compounds is 0.5 to 5: 1 is preferably 0.9 to 3: 1 and in particular 0.95 to 2: 1.

If appropriate, it can be advantageous for the polyurethanes to contain isocyanurate groups at least in part. In these cases, a ratio of NCO groups of the polyisocyanates to the sum of the reactive hydrogen atoms of 1.5 to 60: 1, preferably 1.5 to 8: 1, can preferably be selected.

The polyisocyanate polyaddition products can be produced, for example, by the one-shot process or the known prepolymer process, for example using high-pressure or low-pressure technology in open or closed molds, reaction extruders or belt systems. The flexible polyurethane foams are preferably produced by the one-shot process.

Foamed polyisocyanate polyadducts, for example foamed polyurethane and / or polyisocyanurates, are preferably produced with the mixtures according to the invention.

It has proven to be advantageous to prepare the polyisocyanate polyaddition products by the two-component process and to combine the isocyanate-reactive compounds and, if appropriate, the catalysts, blowing agents and / or auxiliaries and / or additives in the A component and as the B component use the isocyanates and catalysts and / or blowing agents. The inhibitors can be used in the A and / or B component or in the components of these components, preferably in the A component or components of the A component.

The invention is illustrated by the following examples. Examples:

In order to simulate conditions that can occur in the above-mentioned special applications, moist heat aging was carried out with samples of the soft foams mentioned below. For this purpose, test cubes with an edge length of 3 cm at 90 ° C and 90% rel. Humidity aged for 72 hours in a climate cabinet. Under these conditions, hydrolytic cleavage of urethane and urea bonds can occur. This leads not only to a drastic deterioration in the mechanical properties, but also to the formation of aromatic amines.

For this reason, the MDA or TDA content of the foams produced was measured both in the untreated state and after aging under heat and moisture, in addition to the compression set, resilience and compression hardness.

The aromatic amines were extracted using a method developed by Prof. Skarping, University of Lund. For this purpose, the foam is squeezed out 10 times with 10 ml of acetic acid (w = 1% by weight). The acetic acid was transferred to a 50 ml volumetric flask with the foam sample compressed. The process is repeated three times and the volumetric flask is filled up to the measuring mark with acetic acid. The MDA content of the combined extracts was then determined by means of capillary electrophoresis with UV detection. The MDA contents given in the examples correspond to the absolute contents of the MDA formed in the PUR foam.

example 1

A component:

97 parts by weight of a polyol with OHZ 28, an average functionality of 2.3 and an EO / PO ratio of 14/86

3 parts by weight of a polyol with the OHZ 42, a medium

Functionality of 3 and a PO / EO ratio of 30/70

3.31 parts by weight of water

0.8 parts by weight of aminopropylimidazole 0.6 parts by weight of Lupragen N107, OH number: 421 (BASF)

0.5 part by weight of Tegostab B 8631 (Goldschmidt) Component B

Mixture of a polymer MDI with a proportion of 50% and a mixture of 2,4'-MDI and 4,4'-MDI in a ratio of 1: 1 with a proportion of 50%.

oL: without wet heat storage mL: after wet heat storage

Example 2

Production of a flexible polyurethane foam in analogy to 1), hereinafter referred to as test system 1 with the difference that the A component contained 5% by weight γ-butyrolactone in dissolved form.

oL: without wet heat storage mL: after wet heat storage

Example 3

Production of a flexible polyurethane foam in analogy to 1), hereinafter referred to as test system 2 with the difference that the A component contained 5% by weight ε-caprolactone in dissolved form.

OL: without wet heat storage _m .L. : after moist heat storage Example 4

Production of a flexible polyurethane foam in analogy to 1), hereinafter referred to as test system 3 with the difference that the A component contained 5% by weight γ-decanolactone in dissolved form.

oL: without wet heat storage mL: after wet heat storage

Example 5

Production of a flexible polyurethane foam in analogy to 1) hereinafter referred to as test system 4, with the difference that the A component contained 5% by weight δ-dodecanolactone in dissolved form.

oL: without wet heat storage mL: after wet heat storage

Example 6

Production of a flexible polyurethane foam in analogy to 1), hereinafter referred to as test system 5 with the difference that the A component contained 5% by weight of 2-pyrrolidone in dissolved form.

oL: without wet heat storage mL: after wet heat storage Example 7

Production of a flexible polyurethane foam in analogy to 1), hereinafter referred to as test system 6 with the difference that the A component contained 5% by weight δ-valerolactam in dissolved form.

oL: without wet heat storage mL: after wet heat storage

Example 8

Production of a flexible polyurethane foam in analogy to 1), hereinafter referred to as test system 7 with the difference that the A component contained 5% by weight of cycledistillate in dissolved form.

oL: without wet heat storage mL: after wet heat storage

Cycled distillate: distillation residue that arises in the synthesis of polyester polyols based on ADS-DEG-trimethylolpropane and approx. 40 - 50% by mass of low molecular weight cyclic esters, i.e. Condensation products from diethylene glycol (DEG) and adipic acid (ADS), e.g. Contains DEG-ADS esters and ADS-DEG-ADS-DEG esters as well as DEG and low molecular weight linear esters.

discussion of the results

The advantages according to the invention, ie the significantly reduced content of primary aromatic amines after storage under warm, moist conditions by adding lactones and lactams and, in particular, low molecular weight cyclic esters based on DEG / ADS in polyurethane foams, could be demonstrated convincingly on the basis of the examples given. In the case of the compounds mentioned, a chemical reaction of the primary amines to the corresponding substituted ones takes place with ring opening Carboxamides instead. In addition, hydrolytic cleavage of the lactones and lactams to the corresponding hydroxy or aminocarboxylic acids is also possible. These carboxylic acids in turn are capable of deactivating the tertiary amine catalysts used by protonating the catalytically active tertiary nitrogen and thus significantly preventing its activity from cleaving urethane and urea bonds. By adding the lactone and lactam compounds according to the invention or the cyclic esters, significantly fewer urethane and urea bonds are consequently split. This manifests itself not only in significantly smaller amounts of extractable primary amines, but also in a significantly lower deterioration in the mechanical properties of the foams (test systems) after storage under moist heat. As the results also show, the test systems show a significantly smaller drop in the resilience after wet-heat aging compared to the two comparison systems. The compression set remains at a much lower level, while the compression hardness generally drops to a lower level, which is due to the already known softening effect of the lactones and lactams. The added lactone and lactam compounds and the cyclic esters are therefore suitable as stabilizers against hydrolytic cleavage of urethane and urea bonds and thus against the formation of primary amines in polyurethane products. Another advantage, which becomes clear when looking at the examples, is the improvement of the compression set before the moist heat storage, in particular through the addition of cyclic esters based on DEG / ADS. In addition to their function as hydrolysis stabilizers, the compounds according to the invention are also suitable as additives for the production of polyisocyanate polyaddition products with improved compression set (lower DVR values in the finished foam).

Claims

claims

1. Flexible polyurethane foams with a density of 15 to 300 kg / m ³ containing lactones, lactams and / or cyclic esters.

2. Mattresses or upholstery for furniture or carpets containing flexible polyurethane foams according to claim 1.

3. Process for the production of flexible polyurethane foams with a density of 15 to 300 kg / m ³ , characterized in that the production is carried out in the presence of lactones, lactams and / or cyclic esters.

4. Use of lactones, lactams and / or cyclic esters to deactivate aminic catalysts in polyisocyanate polyadducts.

Use of lactones, lactams and / or cyclic esters to reduce the content of primary amines in polyisocyanate polyadducts.

6. Use of lactones, lactams and / or cyclic esters to improve the mechanical properties in polyisocyanate polyadducts.

7. Use according to claim 4, 5 or 6 in processes for the preparation of polyisocyanate polyadducts.

8. Use according to claim 4, 5 or 6 in flexible polyurethane foams.