EP4314104A1

EP4314104A1 - Method for reducing aromatic (di)amines in polyurethane foams

Info

Publication number: EP4314104A1
Application number: EP22712003.7A
Authority: EP
Inventors: Joern Beaujean; Sebastian SCHLECHT; Matthaeus Gossner
Original assignee: Covestro Deutschland AG
Current assignee: Covestro Deutschland AG
Priority date: 2021-03-23
Filing date: 2022-03-17
Publication date: 2024-02-07
Also published as: WO2022200176A1

Abstract

The present invention relates to a method for producing polyurethane foams by reacting component A containing A1 an isocyanate-reactive component, A2 blowing agent containing water, A3 optionally auxiliary agent and additive, A4 a compound having the formula P[-O-C(O)-CH₂-C(X)-R¹]_n (I), wherein P stands for a polyether polyol having an OH functionality of 2 to 8 and a number-average molecular weight of 200 to 4000 g/mol, measured in accordance with DIN 55672-1 from August 2007, X stands for =O or =N-R², R¹ and R² stand, independently of each other, for a substituted or unsubstituted C₁ to C₈ alkyl group or a substituted or unsubstituted aryl group and n stands for the number of OH groups of P which are replaced by the group -O-C(O)-CH₂-C(X)-R¹ and is at least 1, with component B, an isocyanate component containing toluene diisocyanate, diphenylmethane diisocyanate, polyphenyl polymethylene polyisocyanate or mixtures of said compounds, at an isocyanate index of 100 or less. The invention also relates to polyurethane foams according to the method, to the use of the polyurethane foams and to the use of the component A4.

Description

PROCESS FOR REDUCING AROMATIC (DI-)AMINES IN POLYURETHANE FOAM MATERIALS

The present invention relates to a process for producing polyurethane foams using vvoonn emission-reducing compounds, the polyurethane foams themselves and the use of the emission-reducing compounds.

In the production of polyurethane foams, compounds are formed as by-products that can be emitted from the polyurethane foams. Examples of this are the formation of aromatic (di)amines such as e.g. toluenediamine (TDA) and methylenedianiline (MDA), which occur with isocyanate numbers below 100 and when larger amounts of water are used. Due to the harmful properties of these compounds, it is necessary to reduce the formation or emission of traces of these compounds.

Additives for reducing aromatic amines are known from the prior art. Thus, in DE 199 19 826 A1, α,β-unsaturated carboxylic acids, α,β-unsaturated carboxylic acid derivatives, α,β-unsaturated ketones and/or α,β-unsaturated aldehydes are disclosed for the reduction of aromatic amines in the production of polyurethane foams, such as for example hydroxyethyl acrylate. Another group for reducing aromatic amines are, for example, lactams, as disclosed in DE 199 28 687 A1 and in WO 2020/084003 A1. However, a compound as claimed in claim 1 is not used in any of these disclosures.

The object of the present invention is to provide a process for producing polyurethane foams with a reduced proportion of aromatic amines, in a preferred embodiment a reduced proportion of the total emissions, by reducing the emission of the additive.

This object is achieved by a process for producing polyurethane foams by reacting component A

A1 an isocyanate-reactive component,

A2 propellant containing water,

A3 Auxiliary and additive if necessary.

A4 a compound of formula

P[-OC(O)-CH ₂ -C(X)-R ¹ ] _n (I) wherein

P is a polyether polyol with an OH functionality of 2 to 8 and a number average molecular weight of 200 to 4000 g/mol, measured according to DIN 55672-1 of August 2007,

X is =0 or =NR ² , R ¹ , R ² each independently represent a substituted or unsubstituted C ₁ - to C ₈ - alkyl group or a substituted or unsubstituted aryl group, n represents the number of OH groups of P which is represented by the group -OC(O) - CH ₂ -C (X) - R ¹ are replaced and is at least 1, with

B an isocyanate component containing toluylene diisocyanate, diphenylmethane diisocyanate, polyphenylpolymethylene polyisocyanate or a mixture of the compounds mentioned, with an isocyanate index of 100 or less, preferably 90 or less.

The present invention also provides the polyurethane foams obtainable by the process described and the use of the compound of the formula (I) for reducing the proportion of aromatic amines.

Component A1

For example, polyols selected from the group consisting of polyether polyols, polyester polyols, polyether ester polyols, polycarbonate polyols and polyether-polycarbonate polyols can be used as isocyanate-reactive components. Polyester polyols and/or polyether polyols are preferred. The compounds of component A1 can have an amine and/or hydroxyl number of between 15 and 4000 mg KOH/g and a functionality of 1 to 8. The compounds of component A1 preferably have a number-average molecular weight of 2000 g/mol to 15000 g/mol, in particular 3000 g/mol to 12000 g/mol and particularly preferably 3500 g/mol to 6500 g/mol. If more than one compound of component A1 is used, the mixture of compounds of component A1 can preferably have a hydroxyl number of between 20 and 200 mg KOH/g, in particular 25 to 100 mg KOH/g.

“Functionality” in the context of the present invention denotes the theoretical average functionality (number of functions in the molecule that are reactive toward isocyanates or toward polyols) calculated from the known starting materials and their quantitative ratios.

In the context of this invention, the number-average molar mass M _n (also: molecular weight) is determined by gel permeation chromatography in accordance with DIN 55672-1 (August 2007).

Polyetherester polyols which can be used are those compounds which contain ether groups, ester groups and OH groups. Organic dicarboxylic acids having up to 12 carbon atoms are preferably used to prepare the polyetherester polyols, preferably aliphatic dicarboxylic acids having 4 to 6 carbon atoms or aromatic dicarboxylic acids, which are used individually or as a mixture. Examples include suberic acid, azelaic acid, decanedioic acid, malonic acid, phthalic acid, pimelic acid and sebacic acid and, in particular, glutaric acid, fumaric acid, succinic acid, adipic acid, phthalic acid, terephthalic acid and isoterephthalic acid called. In addition to organic dicarboxylic acids, it is also possible to use derivatives of these acids, for example their anhydrides and their esters and half-esters with low molecular weight, monofunctional alcohols having 1 to 4 carbon atoms. The proportionate use of the above bio-based starting materials, in particular fatty acids or fatty acid derivatives (oleic acid, soybean oil etc.) is also possible and can have advantages, for example with regard to storage stability of the polyol formulation, dimensional stability, fire behavior and compressive strength of the foams.

Polyether polyols obtained by alkoxylating starter molecules such as polyhydric alcohols are used as a further component for the production of the polyetherester polyols. The starter molecules are at least difunctional, but may also contain proportions of higher-functional, in particular trifunctional, starter molecules.

Starter molecules are, for example, ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentenediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,10-decanediol, 2-methylpropane-1,3-diol, neopentyl glycol, 2,2-dimethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-butyl-2-ethyl-1, 3-propanediol, 2-butene-1,4-diol and 2-butyne-1,4-diol, diethylene glycol, dipropylene glycol, glycerol, trimethylolpropane, di- and trifunctional polyether polyols. The polyether polyols preferably have an OH functionality of 2 to 4 and a molecular weight M _n in the range from 62 to 4500 g/mol and in particular a molecular weight M _n in the range from 62 to 3000 g/mol. Starter molecules with functionalities other than OH can also be used alone or in a mixture.

Polyetheresterpolyols can also be produced by the alkoxylation, in particular by ethoxylation and/or propoxylation, of reaction products obtained by reacting organic dicarboxylic acids and their derivatives and components with Zerewitinoff-active hydrogens, in particular diols and polyols. Examples of derivatives of these acids that can be used are their anhydrides.

The polyester polyols of component Al can, for example, polycondensates of polyhydric alcohols, preferably diols, atoms having 2 to 12 carbon atoms, preferably having 2 to 6 carbon atoms, and polycarboxylic acids, such as. B. di-, tri- or even tetracarboxylic acids or hydroxycarboxylic acids or lactones, aromatic dicarboxylic acids or mixtures of aromatic and aliphatic dicarboxylic acids are preferably used. Instead of the free polycarboxylic acids, the corresponding polycarboxylic acid anhydrides or corresponding polycarboxylic acid esters of lower alcohols can also be used to prepare the polyester.

Particularly suitable carboxylic acids are: succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, decanedioic acid, tetrahydrophthalic acid, Hexahydrophthalic acid, cyclohexanedicarboxylic acid, tetrachlorophthalic acid, itaconic acid, malonic acid, 2-methylsuccinic acid, 3,3-diethylglutaric acid, 2,2-dimethylsuccinic acid, dodecanedioic acid, endomethylenetetrahydrophthalic acid, dimer fatty acid, trimer fatty acid, citric acid, trimellitic acid, benzoic acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid and terephthalic acid. Derivatives of these carboxylic acids, such as dimethyl terephthalate, can also be used. The carboxylic acids can be used either individually or as a mixture. The carboxylic acids used are preferably adipic acid, sebacic acid and/or succinic acid, particularly preferably adipic acid and/or succinic acid.

Examples of hydroxycarboxylic acids which can be used as reactants in the preparation of a hydroxyl-terminated polyester polyol are lactic acid, malic acid, hydroxycaproic acid, hydroxybutyric acid, hydroxydecanoic acid, hydroxystearic acid and the like. Suitable lactones include caprolactone, butyrolactone and homologues.

In particular, bio-based starting materials and/or their derivatives can also be used for the production of polyester polyols, e.g. B. Castor oil, polyhydroxy fatty acids, ricinoleic acid, hydroxyl-modified oils, grape seed oil, black cumin oil, pumpkin seed oil, borage seed oil, soybean oil, wheat seed oil, rapeseed oil, sunflower seed oil, peanut oil, apricot kernel oil, pistachio oil, almond oil, olive oil, macadamia nut oil, avocado oil, sea buckthorn oil, sesame oil, hemp oil, Hazelnut oil, primrose oil, wild rose oil, safflower oil, walnut oil, fatty acids, hydroxyl-modified and epoxidized fatty acids and fatty acid esters, for example based on myristoleic acid, palmitoleic acid, oleic acid, vaccenic acid, petroselinic acid, gadoleic acid, erucic acid, nervonic acid, linoleic acid, alpha- and gamma-linolenic acid, stearidonic acid, arachidonic acid , timnodonic acid, clupanodonic acid and cervonic acid. Esters of ricinoleic acid with polyhydric alcohols, e.g., glycerol, are particularly preferred. The use of mixtures of such bio-based acids with other carboxylic acids, e.g. phthalic acids, is also preferred.

Examples of suitable diols are ethylene glycol, butylene glycol, diethylene glycol, triethylene glycol, polyalkylene glycols such as polyethylene glycol, also 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol and isomers, neopentyl glycol or

Hydroxypivalic Acid Neopentyl Glycol Ester. Ethylene glycol, diethylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol or mixtures of at least two of the diols mentioned, in particular mixtures of 1,4-butanediol, 1,5-pentanediol and 1, 6-hexanediol.

In addition, polyols such as trimethylolpropane, glycerol, erythritol, pentaerythritol, trimethylolbenzene or trishydroxyethyl isocyanurate can also be used, glycerol and trimethylolpropane being preferred. In addition, monohydric alkanols can also be used.

Polyether polyols used according to the invention are obtained by production methods known to those skilled in the art, such as, for example, by anionic polymerization of one or more alkylene oxides having 2 to 4 carbon atoms with alkali metal hydroxides, such as sodium or potassium hydroxide, alkali metal alkoxides, such as sodium methylate, sodium or potassium ethylate or potassium isopropylate, or amine alkoxylation -Catalysts, such as dimethylethanolamine (DMEOA), imidazole and/or imidazole derivatives, using at least one starter molecule which contains 2 to 8, preferably 2 to 6, bonded reactive hydrogen atoms.

Examples of suitable alkylene oxides are 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 one after the other, or as mixtures. Preferred alkylene oxides are propylene oxide and ethylene oxide, and particular preference is given to copolymers of propylene oxide with ethylene oxide. The alkylene oxides can be reacted in combination with CO ₂ .

Examples of suitable starter molecules are: water, organic dicarboxylic acids such as succinic acid, adipic acid, phthalic acid and terephthalic acid, aliphatic and aromatic, optionally N-mono-, N,N- and N,N'-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, phenylenediamines, 2,3-, 2,4- and 2,6-tolylenediamine and 2,2'-, 2,4'- and 4,4'-diaminodiphenylmethane.

Preferably used are dihydric or polyhydric alcohols such as ethanediol, 1,2- and 1,3-propanediol, diethylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, paraformaldehyde, triethanolamine, bisphenols, glycerol, trimethylolpropane, pentaerythritol, sorbitol and sucrose.

Polycarbonate polyols which can be used are polycarbonates containing hydroxyl groups, for example polycarbonate diols. These arise in the reaction of carbonic acid derivatives, such as diphenyl carbonate, dimethyl carbonate or phosgene, with polyols, preferably diols.

Examples of such diols are ethylene glycol, 1,2- and 1,3-propanediol, 1,3- and 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, neopentyl glycol, 1,4-bishydroxymethylcyclohexane, 2- Methyl-1,3-propanediol, 2,2,4-trimethylpentanediol-1,3, dipropylene glycol, polypropylene glycols, dibutylene glycol, polybutylene glycols, bisphenols and lactone-modified diols of the type mentioned above. Instead of or in addition to pure polycarbonate diols, it is also possible to use polyether-polycarbonate diols, which are obtainable, for example, by copolymerization of alkylene oxides, such as propylene oxide, with CO ₂ .

Polymer polyols, PHD polyols and PIPA polyols can also be used in component A1 as isocyanate-reactive components. Polymer polyols are polyols containing proportions of solid polymers produced by free radical polymerization of suitable monomers such as styrene or acrylonitrile in a base polyol. PHD (polyhydrazodicarbonamide) polyols are produced, for example, by in situ polymerization of an isocyanate or an isocyanate mixture with a diamine and/or hydrazine (or hydrazine hydrate) in a polyol, preferably a polyether polyol. The PHD dispersion is preferably prepared by reacting an isocyanate mixture of 75 to 85% by weight of 2,4-tolylene diisocyanate (2,4-TDI) and 15 to 25% by weight of 2,6-tolylene diisocyanate (2,6 -TDI) with a diamine and/or hydrazine hydrate in a polyether polyol prepared by alkoxylating a trifunctional starter (such as glycerol and/or trimethylolpropane). PIPA polyols are polyether polyols modified by polyisocyanate polyaddition with alkanolamines, the polyether polyol preferably having a functionality of 2.5 to 4.0 and a hydroxyl number of 3 mg KOH/g to 112 mg KOH/g (molecular weight 500 g/mol to 18000 g/mol).

It is also possible to use isocyanate-reactive components with a toe-opening effect, such as, for example, copolymers of ethylene oxide and propylene oxide with an excess of ethylene oxide or aromatic diamines such as diethyltoluenediamine.

In addition to the isocyanate-reactive compounds described above, component A1 can contain, for example, graft polyols, polyamines, polyamino alcohols and polythiols. The isocyanate-reactive components described also include those compounds with mixed functionalities

For the production of polyurethane foams in the cold foam process, preference is given to using polyethers which have at least two hydroxyl groups and an OH number of 20 to 50 mg KOH/g, the OH groups consisting of at least 80 mol % of primary OH groups (determined by means of ¹ H-NMR (e.g. Bruker DPX 400, deuterochloroform)). The OH number is particularly preferably from 25 to 40 mg KOH/g, very particularly preferably from 25 to 35 mg KOH/g.

If appropriate, compounds having at least two isocyanate-reactive hydrogen atoms and an OH number of 280 to 4000 mg KOH/g, preferably 400 to 3000 mg KOH/g, particularly preferably 1000 to 2000 mg KOH/g, are additionally used in component A1. These are to be understood as meaning compounds containing hydroxyl groups and/or amino groups and/or thiol groups and/or carboxyl groups, preferably Compounds containing hydroxyl groups and/or amino groups, which serve as chain extenders or crosslinking agents. These compounds generally have 2 to 8, preferably 2 to 4, isocyanate-reactive hydrogen atoms. For example, ethanolamine, diethanolamine, triethanolamine, sorbitol and/or glycerol can be used.

Component A1 can consist of one or more of the abovementioned isocyanate-reactive components; component A1 preferably contains polyethers containing at least two hydroxyl groups, optionally mixed with polyesters containing at least two hydroxyl groups.

In a preferred embodiment, component A1 contains:

A11l Compounds containing isocyanates-reactive hydrogen atoms with an NH number according to DIN 53176 in the version of November 2002 and/or OH number according to DIN 53240-1 in the version of June 2013 from 15 to <120 mg KOH/g, optionally

A1.2 isocyanate-reactive compounds containing hydrogen atoms with an NH number according to DIN 53176 in the November 2002 version and/or OH number according to DIN 53240-1 in the June 2013 version of 120 to 600 mg KOH/g, and possibly

A1.3 Compounds containing hydrogen atoms which are reactive towards isocyanates and have an NH number in accordance with DIN 53176 in the November 2002 version and/or OH number in accordance with DIN 53240-1 in the June 2013 version of 600 to 4000 mg KOH/g.

Component A2

Chemical and/or physical blowing agents are used as component A2.

Water or carboxylic acids and mixtures thereof, for example, are used as the chemical blowing agent A2.1. These react with isocyanate groups to form the propellant gas, for example in the case of water, carbon dioxide is formed and in the case of z. B. formic acid produces carbon dioxide and carbon monoxide. At least one compound selected from the group consisting of formic acid, N,N-dialkylcarbamic acid, oxalic acid, malonic acid and ricinoleic acid is preferably used as the carboxylic acid. The ammonium salts of these acids are also suitable. Water is particularly preferably used as the chemical blowing agent. For example, low-boiling organic compounds such as e.g. B. hydrocarbons, ethers, ketones, carboxylic acid esters, carbonic acid esters, halogenated hydrocarbons. Particularly suitable are organic compounds which are inert to the isocyanate component B and have boiling points below 100° C., preferably below 50° C., at atmospheric pressure. These boiling points have the advantage that the organic compounds evaporate under the influence of the exothermic polyaddition reaction. Examples of such preferably used organic compounds are alkanes such as heptane, hexane, n- and isopentane, preferably technical mixtures of n- and isopentanes, n- and isobutane and propane, cycloalkanes such as cyclopentane and/or cyclohexane , Ethers such as furan, dimethyl ether and diethyl ether, ketones such as acetone and methyl ethyl ketone, carboxylic acid alkyl esters such as methyl formate, dimethyl oxalate and ethyl acetate and halogenated hydrocarbons such as methylene chloride, dichloromonofluoromethane, difluoromethane, trifluoromethane, difluoroethane, tetrafluoroethane, chlorodifluoroethane, 1,1-dichloro- 2,2,2-trifluoroethane, 2,2-dichloro-2-fluoroethane and heptafluoropropane. Also preferred is the use of (hydro)fluorinated olefins, such as HFO 1233zd(E) (trans-1-chloro-3,3,3-trifluoro-1-propene) or HFO 1336mzz(Z) (cis-1,1 ,1,4,4,4-hexafluoro-2-butene) or additives such as FA 188 from 3M (1,1,1,2,3,4,5,5,5-nonafluoro-4-(trifluoromethyl)pent- 2-en). Mixtures of two or more of the organic compounds mentioned can also be used. The organic compounds can also be used in the form of an emulsion of small droplets.

In a particular embodiment, the component contains A2

A2.1 0.5 to 5% by weight (based on the total mass of component A) chemical blowing agents and/or

A2.20 to 15% by weight (based on the total mass of component A) physical blowing agents. Particular preference is given to using water as component A2.

Component A3

Auxiliaries and additives are used as component A3, such as a) catalysts (activators), b) surface-active additives (surfactants), such as emulsifiers and foam stabilizers, in particular those with low emissions such as products from the Tegostab ^® LF series, c) additives such as reaction retardants ( For example, acidic substances such as hydrochloric acid or organic acid halides), cell regulators (such as paraffins or fatty alcohols or dimethylpolysiloxanes), pigments, dyes, flame retardants (such as tricresyl phosphate), stabilizers against aging and weathering, plasticizers, fungistatic and bacteriostatic substances, fillers (such as barium sulphate, diatomaceous earth, soot or whiting) and release agents.

Preferred catalysts are aliphatic tertiary amines (e.g. trimethylamine, tetramethylbutanediamine), cycloaliphatic tertiary amines (e.g. 1,4-diaza(2,2,2)bicyclooctane), aliphatic amino ethers (e.g. dimethylaminoethyl ether and N,N,N-trimethyl-N- hydroxyethyl bisaminoethyl ether), cycloaliphatic amino ethers

(e.g. N-ethylmorpholine), aliphatic amidines, cycloaliphatic amidines, urea, derivatives of urea (such as aminoalkylureas), in particular (3-dimethylaminopropylamine)urea) and tin catalysts (such as dibutyltin oxide, dibutyltin dilaurate, tin octoate).

Particularly preferred catalysts are (i) urea, derivatives of urea and/or (ii) the abovementioned amines and amino ethers, characterized in that the amines and amino ethers contain a functional group which reacts chemically with the isocyanate. Preferably the functional group is a hydroxyl group, a primary or secondary amino group. These particularly preferred catalysts have the advantage that they have greatly reduced migration and emission behavior. Examples of particularly preferred catalysts are: (3-dimethylaminopropylamine)-urea, 1,1'-((3-

(dimethylamino)propyl)imino)bis-2-propanol, N-[2-[2-(dimethylamino)ethoxy]ethyl]-N-methyl-1,3-propanediamine and 3-dimethylaminopropylamine.

Component A4

According to the invention, a compound having the formula

P[-OC(O)-CH ₂ -C(X)-R ¹ ] _n (I) wherein

X is =0 or =NR ² ,

R ¹ , R ² each independently represent a substituted or unsubstituted C ₁ - to C ₈ - alkyl group or a substituted or unsubstituted aryl group, n represents the number of OH groups of P represented by the group -OC(O)- CH ₂ -C(X)-R ¹ are replaced and at least 1 is used to reduce the proportion of aromatic (di)amines, preferably toluenediamine (TDA) and/or methylenedianiline (MDA). The compound of formula (I) can, for example, by reacting a polyether polyol P with a ß-keto carboxylic acid ester and optionally subsequent reaction with a primary amine R ² -NH ₂ are prepared. The polyether polyol P can be obtained as described in component A1. The polyether polyol P has an OH functionality of 2 to 8, preferably 2 to 4 and particularly preferably 2 to 3. The molecular weight of the polyether polyol P is 200 to 4000 g/mol, preferably 200 to 2000 g/mol and particularly preferably 200 to 800 g/mol.

In a particular embodiment, the polyether polyol P has an equivalent weight of 50 to 500 g/mol, particularly preferably an equivalent weight of 50 to 500 g/mol and an OH functionality of 2 to 6. The equivalent weight is based on the number-average molecular weight of the Polyetherpolyol P determined.

Acetoacetate esters, 3-oxopentanoic esters, 3-oxohexanoic esters, 4-methyl-3-oxopentanoic esters, benzylacetoacetate esters, 3-oxo-5-phenylpentanoic esters can be used as β-ketocarboxylic acid esters. The .beta.-ketocarboxylic acid ester is preferably an acetoacetate ester, particularly preferably a C.sub.1 _-C.sub.6 _-alkyl ester of acetoacetic acid. R ¹ is preferably a substituted or unsubstituted C ₁ - to C ₈ - alkyl group, preferably a CI to C6 alkyl group, in particular a methyl, ethyl, propyl, or isopropyl group.

The primary amine R ² -NH ₂ has a substituted or unsubstituted C ₁ to C ₈ alkyl group or a substituted or unsubstituted aryl group. R ² is preferably an unsubstituted or substituted C ₁ - to C ₈ -alkyl group, particularly preferably a C ₁ - to C ₈ -alkyl group which has a tertiary amine as a substituent.

In the compound of formula (I), n OH groups of the polyether polyol P are replaced by the group -OC(O)-CH ₂ -C(X)-R ¹ , where n is at least 1. The compound of the formula (I) is preferably a polyether polyol P in which only one free OH group is present or all OH groups are replaced by the group -OC(O)-CH ₂ -C(X)- ^R1 have been replaced.

In a particular embodiment, a compound of the formula (I) is used in which

P is a polyether polyol having an OH functionality of 2 to 6 and an equivalent weight of 50 to 500 g/mol,

R ¹ , R ² each independently represent a substituted or unsubstituted C ₁ - to C ₄ - alkyl group, and only one or two free OH groups are present.

Component A4 is preferably used in a proportion of 0.20 to 10% by weight, particularly preferably 0.3 to 5% by weight, based in each case on the total mass of component A. Component B

Aliphatic, cycloaliphatic, araliphatic, aromatic and heterocyclic polyisocyanates are used as component B, for example those of the formula (II)

Q(NCO) _n (II) in which n is an integer between 2-4, preferably 2 or 3, and

Q is an aliphatic hydrocarbon radical having 2-18, preferably 6-10 carbon atoms, a cycloaliphatic hydrocarbon radical having 4-15, preferably 6-13 carbon atoms or an araliphatic hydrocarbon radical having 8-15, preferably 8-13 carbon atoms .

According to the invention, component B contains toluylene diisocyanate (“TDI”), diphenylmethane diisocyanate, polyphenylpolymethylene polyisocyanate or a mixture of the compounds mentioned. In addition to TDI, other polyisocyanates can be used, such as polyphenylpolymethylene polyisocyanates, such as those produced by aniline-formaldehyde condensation and subsequent phosgenation ("crude MDI") and polyisocyanates containing carbodiimide groups, urethane groups, allophanate groups, isocyanurate groups, urea groups or biuret groups ("modified polyisocyanates"). , In particular those modified polyisocyanates which are derived from 2,4- and/or 2,6-tolylene diisocyanate or from 4,4'- and/or 2,4'-diphenylmethane diisocyanate. As component B, at least one compound is preferably selected from the group consisting of 2,4- and 2,6-

Toluylene diisocyanate, 4,4'- and 2,4'- and 2,2'-diphenylmethane diisocyanate and polyphenylpolymethylene polyisocyanate ("multi-nuclear MDI") are used.

The polyurethane foams obtained according to the invention are preferably flexible polyurethane foams or semirigid polyurethane foams. To produce the polyurethane foams, the reaction components are treated according to the known method

One-step process, the prepolymer process or the semi-prepolymer process are implemented, often using mechanical equipment.

The polyurethane foams can be produced as molded foams or also as block foams, it being possible for the molded foams to be produced in a hot-curing or cold-curing manner. The invention therefore relates to a process for the production of polyurethane foams, the polyurethane foams produced by this process and their use for the production of molded parts or block goods, and the molded parts or block goods themselves. The polyurethane foams obtainable according to the invention are used, for example, in the following areas: furniture upholstery, textile inserts, mattresses, automobile seats, headrests, armrests, sponges and components, as well as seat and instrument paneling, and have indexes of 100 or less, preferably 50 to 90, particularly preferably 65 to 85. The isocyanate index (also known as index or isocyanate index) is the quotient of the amount of substance [mol] of isocyanate groups actually used and the amount of substance [mol] of isocyanate-reactive groups actually used, multiplied by 100:

Index = (moles of isocyanate groups / moles of isocyanate-reactive groups) * 100

The NCO value (also: NCO content, isocyanate content) is determined using EN ISO 11909:2007. Unless otherwise stated, these are the values at 25°C.

In a preferred embodiment of the invention, the invention relates to a process for the production of polyurethane foams, the components

Al containing compounds with isocyanate-reactive hydrogen atoms

A1.1 29.0 to 96.5 wt DIN 53240-1 in the June 2013 version from 20 to < 120 mg KOH/g,

A1.2 0 to 60% by weight (based on the total mass of component A).

Isocyanates containing reactive hydrogen atoms with an NH number according to DIN 53176 in the version of November 2002 and/or OH number according to DIN 53240-1 in the version of June 2013 from 120 to < 600 mg KOH/g,

A1.3 0 to 10% by weight (based on the total mass of component A).

Isocyanates containing reactive hydrogen atoms with an NH number according to DIN 53176 in the November 2002 version and/or OH number according to DIN 53240-1 in the June 2013 version of 600 to 4000 mg KOH/g,

A2 propellant containing

A2.1 0.1 to 10% by weight, preferably 1 to 5% by weight (based in each case on the total mass of component A) chemical blowing agents such as water and/or A2.2 0 to 15% by weight (based on the total mass of component A) physical blowing agents such. e.g. CO ₂ ,

A3 0.5 to 10% by weight (based on the total mass of component A) auxiliaries and additives such as a) catalysts, b) surface-active additives, c) pigments and/or flame retardants,

A4 0.25 to 10% by weight (based on the total mass of component A) of a compound with the formula

P[-OC(O)-CH ₂ -C(X)-R ¹ ] _n (I) wherein

X is =0 or =NR ² ,

R ¹ , R ² each independently represent a substituted or unsubstituted C ₁ - to C ₈ - alkyl group or a substituted or unsubstituted aryl group, n represents the number of OH groups of P which is represented by the group -OC(O)- CH ₂ -C(X)- R ¹ are replaced and is at least 1, with

B Di- and/or polyisocyanates with a content of >50% by weight of difunctional isocyanates, containing toluylene diisocyanate, diphenylmethane diisocyanate,

Polyphenyl polymethylene polyisocyanate or a mixture of said compounds are reacted with one another at an isocyanate index of 100 or less.

examples

Test methods:

The raw density and molded part density was determined in accordance with DIN EN ISO 845 in the October 2009 version. The test specimens had a volume of 80x80x40 mm ³ . The hydroxyl number was determined in accordance with DIN 53240-1 in the June 2013 version.

The content of aromatic amines in the foam was determined for the examples in Table 1 by extraction with 0.1% acetic acid according to Skarping (A. Marand, D. Karlsson, M. Dalene, G. Skarping, Analytica Chimica Acta, 2004. 510, 109-119 J R Johnson, D Karlsson, M Dalene, G Skarping, Analytica Chimica Acta, 2010. 678(1), 117-123), but different from the cited literature without subsequent derivatization. After demolding, the TDA and MDA content of the samples was determined for the first time after 4 hours. The samples were then stored openly for a total of 48 hours (Examples 3 and 4) or 72 hours (Examples 1, 2 and 6 to 9) before the second analysis was carried out (Table 1: "after storage"). The specification NN < 0.06 means that the measured value is below the detection limit and the specification < 0.2 means that the measured value is below the limit of quantification.

The VOC and FOG values for the examples in Table 2 were measured in accordance with the Technical Rule VDA 278 of the Association of the Automotive Industry "Thermal desorption analysis of organic emissions for the characterization of non-metallic automotive materials" in the October 2011 version.

Description of the experiments

raw materials

Al.1-1: Polyether polyol having an OH number of 28 mg KOH/g, prepared by alkoxylating glycerol with a mixture of ethylene oxide and propylene oxide in a proportion of 87/13

Al.1-2: polyol containing filler with 21.6% polyurea dispersion (PHD) as filler and 78.4% of a polyether polyol based on glycerol, ethylene oxide and propylene oxide with a number-average molecular weight of 4007 g/mol and an OH number of 28 mg KOH/g Al.1-3: Polyether polyol based on glycerol, ethylene oxide and propylene oxide with a very high proportion of ethylene oxide groups and an OH number of 37 mg KOH/g

Al.1-4: Polyether polyol with an OH number of 31 mg KOH/g Al.1-5: Dispersion of styrene-acrylonitrile copolymer (42% by weight) in a glycerol-started polypropylene oxide-polyethylene oxide block copolymer (OH number 20 mg KOH/g)

Al.2-1: polyether polyol mixture, catalytically active, OH number 127 mg KOH/g Al.2-2: polyether polyol mixture with a functionality of 1.8 and an OH number of 410 mg KOH/g

Al.3-1: glycerol A2.1-1: water

A3-1: Silicone stabilizer (Niax® L-3222, commercial product from Momentive Performance

materials)

A3-2: tertiary amine catalyst (Polycat® 58, commercial product from Evonik)

A3-3: amine catalyst (Dabco® NE 1091, commercial product from Evonik)

A3-4: Silicone stabilizer (Tegostab® B 8736 LF2, commercial product from Evonik)

A3-5: 33% by weight of triethylenediamine in dipropylene glycol (Dabco 33 LV, commercial product from

Evonik)

A3-6: Amine catalyst (Niax® A-400, commercial product from Momentive Performance

materials)

A3-7 Foam stabilizer Tegostab® B 8783 LF2 (commercial product from Evonik)

A3-8: Bis[2-dimethylamino)ethyl]ether (70 wt%) in dipropylene glycol (30 wt%), Niax®

Catalyst A-I (commercial product of Momentive Performance Materials)

A4-1: Additive based on a polyether polyol with a number average molecular weight of

300 g/mol and an OH functionality of 3, with 85% of the OH groups having been reacted with methyl acetoacetate

A4-2: Additive A4-1, where for 2/3 of the carbonyl groups the oxygen atom is replaced by =N-(CH ₂ ) ₃ -

N(CH ₃ ) ₂ was replaced

B-1: Isocyanate mixture of 70% by weight TDI and 30% by weight 4,4'-MDI and higher homologues

B-2: Isocyanate mixture of 80% by weight 2,4-TDI and 20% by weight 2,6-TDI

B-3: 4,4'-MDI and higher homologues

To produce the polyurethane foams, the necessary amounts of the components listed in Tables 1 to 3, with the exception of the isocyanate, are placed in a paper cup with a metal bottom (volume: approx = 64 mm) charged with air at 4200 rpm for 45 seconds.

The isocyanate is weighed into a suitable beaker and emptied again (flow time: 3 s). This beaker, which is still wet on the inside walls, is tared and refilled with the specified amount of isocyanate. The isocyanate becomes the other Components added (flow time: 3 s). The resulting mixture of isocyanate and the other components is mixed intensively for 5 seconds using an agitator (from Pendraulik). To form a molded foam (Tables 1 and 2), the reaction mixture is poured into an aluminum box mold with a volume of 10 dm ³ at 40° C., with a release agent being applied. The mold is closed and locked. After 10 minutes, the latch is opened and released.

The examples in Table 1 show the effect of the process according to the invention with the additives A4-1 and A4-2 on the proportion of aromatic (di-)amine in the polyurethane foam determined using the Skarping method. Irrespective of the index, the process according to the invention leads to polyurethane foams with lower proportions of aromatic (di-)amine before and after storage of the polyurethane foams.

Due to the catalytically active imine group in additive A4-2, the amount of catalyst in Example 9 had to be adjusted compared to Comparative Example 8, so that a polyurethane foam with the same molding density is obtained.

Table 2 shows the effect of the process according to the invention on formulations based on isocyanate B-2 in accordance with VDA 278. A polyurethane foam without an additive A4 (Example 10) has a total TDA emission of 210 ppm. In contrast, the use of various amounts of additive A4 in polyurethane foams leads to emissions of TDA of only 22 to 119 ppm (Examples 11 to 13).

Table 3 shows the reduction of aromatic (di)amine in the production of viscoelastic polyurethane foams. In Examples 15 and 16, the use of component A4-1 according to the invention leads to a significant reduction in aromatic (di-)amines in the foam compared to reference example 14.

Claims

patent claims

1. Process for the production of polyurethane foams by reacting component A containing

A1 an isocyanate-reactive component,

A2 propellant containing water,

A3 Auxiliary and additive, if necessary.

A4 a compound of formula

P[-OC(O)-CH ₂ -C(X)-R ¹ ] _n (I) wherein

X is =O or =NR ² ,

R ¹ , R ² each independently represents a substituted or unsubstituted C ₁ - to C ₈ - alkyl group or a substituted or unsubstituted aryl group, n represents the number of OH groups of P represented by the group -OC(O)- CH ₂ -C(X)- R ¹ are replaced and is at least 1, with

Component B an isocyanate component containing tolylene diisocyanate, diphenylmethane diisocyanate, polyphenylpolymethylene polyisocyanate or

Mixtures of said compounds with an isocyanate number of 100 or less.

2. The method according to claim 1, wherein P is a polyether polyol having an OH functionality of 2-4.

3. The method according to claim 1 or 2, wherein P is a polyether polyol having a number-average molecular weight of 200 to 2000 g / mol, measured according to DIN 55672-1 of August 2007.

4. The method according to claim 1 or 2, wherein P is a polyether polyol having a number-average molecular weight of 800 to 2000 g / mol, measured according to DIN 55672-1 of August 2007.

5. The method according to any one of claims 1 to 4, wherein R ² contains a tertiary amino group.

6. The method according to any one of claims 1 to 5, wherein n is chosen so that P contains either only one free OH group or no free OH group.

7. The method according to any one of claims 1 to 6, wherein A4 is present in a proportion of 0.25 to 5% by weight, based on the total mass of component A.

8. The method according to any one of claims 1 to 7, wherein the isocyanate index is 50-90.

9. The method according to any one of claims 1 to 8, wherein R ¹ is a substituted or unsubstituted C ₁ - to C ₄ alkyl group.

10. The method according to any one of claims 1 to 8, wherein the compound of formula (I) is obtained by reacting an acetoacetate ester with the polyether polyol P and optionally subsequent reaction with an amine.

11. The method according to claim 1, wherein a compound according to formula (I) is used in which

12. The method according to any one of claims 1 to 11, wherein the component A contains the following components

A1 containing compounds with isocyanate-reactive hydrogen atoms

A1.1 29.0 to 96.5 wt DIN 53240-1 in the June 2013 version from 20 to < 120 mg KOH/g, A1.2 0 to 60% by weight (based on the total mass of component A) of compounds containing isocyanate-reactive hydrogen atoms and having an NH number according to DIN 53176 in the version of November 2002 and/or OH number according to DIN 53240-1 in the June 2013 version from 120 to < 600 mg KOH/g,

A1.3 0 to 10% by weight (based on the total mass of component A) of compounds containing isocyanate-reactive hydrogen atoms and having an NH number in accordance with DIN 53176 in the version of November 2002 and/or OH number in accordance with DIN 53240-1 in the June 2013 version from 600 to 4000 mg KOH/g,

A2 propellant containing

A2.1 0.1 to 10% by weight, preferably 1 to 5% by weight (in each case based on the total mass of component A) chemical blowing agents such as water and/or

A2.2 0 to 15% by weight (based on the total mass of component A) physical blowing agents such as e.g. e.g. CO ₂ ,

A3 0.5 to 10% by weight (based on the total mass of component A) auxiliary and

Additives such as a) catalysts, b) surface-active additives, c) pigments and/or flame retardants,

A4 0.25 to 5% by weight (based on the total mass of component A).

Compound of formula (I).

13. polyurethane foam produced by a method according to any one of claims 1 to

12.

14. Use of the polyurethane foams according to claim 13 for the production of

Furniture upholstery, textile inserts, mattresses, automobile seats, headrests, armrests, sponges, foam sheets for use in automobile parts such as headliners, door quarter panels, seat pads and structural elements.

15. Use of a compound of formula (I)

P[-OC(O)-CH ₂ -C(X)-R ¹ ] _n (I) wherein P is a polyether polyol with an OH functionality of 2 to 8 and a number average molecular weight of 200 to 4000 g/mol, measured according to DIN 55672-1 of August 2007,

X is =O or =NR ² , R ¹ , R ² are each independently a substituted or unsubstituted C ₁ - to C ₈ -

alkyl group or a substituted or unsubstituted aryl group, n represents the number of OH groups of P which are replaced by the group -OC(O)-CH ₂ -C(X)- R ¹ and is at least 1, for the reduction of aromatic (di)amine, preferably toluylenediamine and/or methylenedianiline, in polyurethane foams.