WO2004024818A1

WO2004024818A1 - Polyoxymethylene compositions containing selected formaldehyde scavengers and the use thereof

Info

Publication number: WO2004024818A1
Application number: PCT/EP2003/009076
Authority: WO
Inventors: Stefan Wulf; Dirk Zierer; Klaus Kurz
Original assignee: Ticona Gmbh
Priority date: 2002-08-29
Filing date: 2003-08-16
Publication date: 2004-03-25
Also published as: DE10239697B4; DE10239697A1; AU2003264058A1

Abstract

The invention relates to polyoxymethylene molding materials containing compounds of formula (I) R1-[X-CO-NH-R3-NH-CO-NR2-R4]o, wherein R1 to R3, X and o have the meanings as defined in Claim 1. The compounds of formula (I) are suited for use as formaldehyde scavengers in polyoxymethylene molding materials.

Description

description

POLYXYMETHY COMPOSITIONS CONTAINING SELECTED FORMALDEHYDE CATCHERS AND THEIR USE

The present invention relates to new polyoxymethylene molding compositions and selected formaldehyde scavengers.

In the manufacture and thermoplastic processing of

Polyoxymethylene compositions release small amounts of formaldehyde. This can be dissolved formaldehyde, which outgasses from the melt and the hot moldings, or it can be formaldehyde, which was formed when the composition was heated by being split off from the polymer.

The presence of formaldehyde is undesirable for several reasons. On the one hand, due to its physiological concern, it represents a burden for the operating personnel and, on the other hand, deposits can form on the tools, which lead to an impairment of the surface quality and the dimensional accuracy of the molded parts.

There has been no shortage of attempts to reduce the emission of formaldehyde in the production and processing of polyoxymethylene molding compositions. So-called formaldehyde scavengers are usually used for this. such

Compounds often have primary and aromatically bound amino groups which react with the formaldehyde to form methylol groups and thus remove it from the reaction system.

Formaldehyde scavengers containing 2,4-diamothazinyl groups have also become known. Such compounds are described in EP-A-202,530. These include condensates of 4,6-diamino-1,3,5-triazine with short-chain polyaminoalkylenes. Other compounds containing amino groups have also already been used as formaldehyde scavengers in polyoxymethylene molding compositions, for example aminopyridines, guanamines or allantoin.

The efficiency of the formaldehyde scavengers depends, among other things, on the amount of additives that are mixed into the molding compositions. In principle, therefore, the highest possible amount of these additives is sought. However, high amounts of additives can impair the processing properties of the molding compositions or lead to a deterioration in the quality of the products produced, for example as a result of the increased formation of mold coatings.

It has now been found that the concentration of melamine groups in the molding composition can be increased without having to accept the disadvantages described above when coupling selected groups which bind the formaldehyde to selected oligomers.

The present invention provides amino functionalities with suitable basicities for polyoxymethylene molding compositions, so that the formaldehyde emission can be significantly reduced without other disadvantages for the polymer, such as yellowing, or for its processing, such as the formation of moldings, in purchase to have to take.

According to the invention, selected formaldehyde scavengers were reacted with and reacted with selected isocyanate group-containing reagents

How to obtain immobilized formaldehyde scavengers.

Isocyanates blocked with nitrogen-containing compounds are already known from EP-A-1, 031, 589. The compounds described there are said to form supramolecular complexes through the formation of hydrogen bonds and the

Individual components are characterized by a molecular weight of less than 20,000. The stabilization of polyoxymethylene molding compositions or their use as formaldehyde scavengers is not described. The present invention relates to compositions comprising at least one polyoxymethylene homo- and / or copolymer and at least one compound of the formula I.

R ¹ - [X-CO-NH-R ³ -NH-CO-NR ² -R ⁴ ] ₀ (I),

where R ^{1 is} the divalent to hexavalent radical of an alcohol or amine, X is -O- or -NR ² -, R ^{2 is} hydrogen, alkyl, cycloalkyl, aryl or aralkyl,

R ^{3 is} alkylene, cycloalkylene, arylene or aralkylene,

R ^{4 is} a radical which is selected from the radicals of the formulas II, III, IV, V, VI and VII

(VI), -HN-C (= NH) -NH-CN (VII),

wherein R ^{5 is} hydrogen, -CO-CH ₃ or -CO-C ₆ H ₅ , o is an integer between 2 and 6 and p is 1 or 2. If any radicals are alkyl, these are generally saturated alkyl radicals having one to twenty carbon atoms. The alkyl radicals can be straight-chain or branched.

The alkyl radicals can also carry inert substituents, for example alkoxy radicals with preferably one to six carbon atoms, or halogen atoms, such as chlorine.

Straight-chain alkyl radicals having one to six, preferably one to three, carbon atoms are preferred. Methyl is particularly preferred.

If any radicals are cycloalkyl, these are generally saturated cycloalkyl radicals having five to eight, preferably five or six, ring carbon atoms.

The cycloalkyl radicals can also carry inert substituents, for example alkyl or alkoxy radicals with preferably one to six carbon atoms, or halogen atoms, such as chlorine.

Cyclopentyl or cyclohexyl are preferred.

If any radicals are aryl, these are generally aromatic hydrocarbon radicals with one or two aromatic nuclei, which may also have one or two ring heteroatoms, such as nitrogen, sulfur or

May have oxygen.

The aryl radicals can also carry inert substituents, for example alkyl or alkoxy radicals having preferably one to six carbon atoms, or halogen atoms, such as chlorine.

Phenyl is preferred. If any radicals are aralkyl, these are generally aromatic hydrocarbon radicals with one or two aromatic nuclei which also have an alkylene chain.

The aralkyl radicals can also carry inert substituents, for example alkyl or alkoxy radicals with preferably one to six carbon atoms, or halogen atoms, such as chlorine.

Benzyl is preferred.

Preferred radicals R ² are methyl or preferably hydrogen.

If any residues are alkylene, these are generally saturated alkylene residues with two to twenty carbon atoms. The alkylene radicals can be straight-chain or branched.

The alkylene radicals can also carry inert substituents, for example alkoxy radicals with preferably one to six carbon atoms, or halogen atoms, such as chlorine.

Alkylene radicals with two to six are preferred. Ethylene is particularly preferred.

Any cycloalkylene radicals are generally saturated cycloalkylene radicals having five to eight, preferably five or six

Ring carbon atoms.

The cycloalkylene radicals can also carry inert substituents, for example alkyl or alkoxy radicals with preferably one to six carbon atoms, or halogen atoms, such as chlorine.

Cyclopentylene or cyclohexylene are preferred. If any radicals are arylene, these are generally aromatic hydrocarbon radicals having one or two aromatic nuclei, which may also have one or two ring heteroatoms, such as nitrogen, sulfur or oxygen.

The arylene radicals can also carry inert substituents, for example alkyl or alkoxy radicals with preferably one to six carbon atoms, or halogen atoms, such as chlorine.

Preferred are phenylene, especially 1, 3- and 1, 4-phenylene, ^{biphen-4,4'-diyl,}

^{Diphenylmethane-4,4'-diyl,} or naphthylene.

If any radicals mean aralkylene, these are generally aromatic hydrocarbon radicals with one or two aromatic nuclei which also have an alkylene chain.

The aralkylene radicals can also carry inert substituents, for example alkyl or alkoxy radicals with preferably one to six carbon atoms, or halogen atoms, such as chlorine.

R ¹ is the di- to hexavalent residue of an alcohol or amine after removal of the alcohol or amino groups. These can be low molecular weight or also oligomeric or polymeric compounds.

Examples of low molecular weight radicals R ¹ are those listed above for R ²

Alkylene, cycloalkylene, arylene or aralkylene radicals or also tri- or tetravalent radicals which are derived from trimethylolpropane, pentaerythritol or H2N-CH2-CH2-NH-CH2-CH ₂ -NH2.

Preferred are compositions in which R ^{1 is} a radical of the formula —CnH ₂ n-, in which n is an integer from 2 to 4, phenylene, trimethylolpropane without the three hydroxyl groups, pentaerythritol without the four hydroxyl groups, or a sugar without the six hydroxyl groups , Examples of oligomeric or polymeric residues R ¹ are residues of a polyether, polyester, polyamide, polyacrylate, polyolefin, polysiloxane or polycarbonate having di- to tetravalent hydroxyl or amino end groups after the end groups have been removed.

These are particularly preferably radicals of a polyether or polyester which have di- to tetravalent hydroxyl or amino end groups after the end groups have been removed and which have the recurring structural units of the formulas VIII, IX, X or XI

- [R ⁶ -O-] _x -R ⁶ - (VIII), R ⁷ - [[- 0-R ⁶ -] _x -] _p (IX),

- [R ⁸ -O-CO-R ⁹ -CO-0-] _y -R ⁸ - (X), R ¹⁰ - [[O-CO-R ⁹ -CO-OR ⁸ -] _y ] _p - (XI )

in which R ⁶ , R ⁸ and R ⁹ independently of one another are alkylene, cycloalkylene, arylene or aralkylene,

R ⁷ and R ^{10 are} residues of a di to tetravalent aliphatic, cycloaliphatic, aromatic or araliphatic alcohol, x and y are integers from 1 to 200, and p is an integer from 2 to 4.

R ⁶ and R ⁸ are very particularly preferably radicals of the formula -CH ₂ -CH ₂ -, -CH (CH ₃ ) - CH- or -CH ₂ -CH2-CH2-CH2-, R ⁹ is a radical of the formula -C _m H ₂ m-, where m is an integer from 2 to 6, or a phenylene radical, and R ⁷ and R ¹⁰ are radicals of

Formula -C _n H ₂ n-, phenylene, trimethylolpropane without the three hydroxyl groups or pentaerythritol without the four hydroxyl groups.

In further preferred, X is -NH- or in particular -O-.

In the compounds of the formula I, the compositions according to the invention contain structural units R ³ which are derived from a diisocyanate. Any diisocyanates can be used.

Preferred radicals are R ³ , the radicals of the formula -C _P H2 _P -, in which p is an integer from 2 to 18, or a divalent radical of a cycloalkylene having five to eight ring carbon atoms, a phenylene or naphthylene radical, where these radicals can have one to four substituents which are selected from the group consisting of alkyl, alkoxy, cycloalkyl, cycloalkyloxy, aryl and aryloxy.

Compositions in which R ^{3 is} a divalent one are very particularly preferred

Rest is derived from 4-methylpentane, 5-methylhexane, 1-methylcyclohexane, 6-methylheptane, 2,2,5-trimethylheptane, 3,7-dimethyloctane, 1, 2,2-trimethylcyclopentane, 1, 4- or 1, 3-Dimethylcyclohexane, toluene, biphenyl, diphenylmethane, dicyclohexyimethane, isophorone and hexane.

Compositions in which R ^{4 is} a radical of the formula V or in particular the formula II and which preferably have recurring structural units of the formulas VIII, IX, X or XI, in which x or y are integers from 8 to 15, are particularly preferred.

Compositions in which o is 2 are further preferred.

The invention also relates to selected and new compounds of the formula I in which X, R ¹ , R ² , R ³ , R ⁴ , R ⁵ and o have the meanings defined above, with the proviso that when R ^{4 is} a radical of the formula II, III, IV, VI or VII, R ^{1 is} the radical of a polyether or polyester having di- to tetravalent hydroxyl or amino end groups after removal of the end groups, which is the repeating structural units of the formulas VIII, IX, X or XI defined above and where the indices x, y and p assume values such that the compound of the formula I has a molecular weight of at least 800, preferably at least 800 to 5,000, particularly preferably from 850 to 2,200. The invention furthermore relates to the use of the compound of the formula I for reducing the formaldehyde emission of polyoxymethylene homo- or copolymers.

The compounds of the formula I used according to the invention can be obtained by processes known per se by reacting dihydric alcohols or amines of the formula XII with diisocyanates of the formula XIII and then capping the free isocyanate groups of the resulting adduct with amines of the formula XIV

R ¹ - [XH] ₀ (XII), NCO-R ³ -NCO (XIII),

R ⁴ -NH ₂ (XIV),

wherein R ¹ , R ³ , R ⁴ , X and o have the meaning defined above.

In the reaction, the compounds of the formulas XII and XIII are used in such an amount that the free alcohol or amino groups of the compound of the formula XII are in each case blocked by an isocyanate group of the compound of the formula XIII and only one isocyanate group of the

Diisocyanate XIII reacted. By introducing an excess of diisocyanate XIII and / or a diisocyanate XIII with two differently reactive isocyanate groups, polymeric adducts can be prevented from forming.

The reaction is typically carried out in an organic solvent, for example in dipolar aprotic solvents, such as DMSO, or in aromatic hydrocarbons, such as toluene or xylene, which are liquid at reaction temperatures.

The reaction temperatures are usually 0 to 220 ° C, preferably 30 to 150 ° C. The first stage of the reaction usually takes place at lower temperatures, for example at 0 to 50 ° C., and the second stage of the reaction usually takes place at higher temperatures, for example at 50 to 150 ° C. It is of course also possible to carry out both reaction stages at the same temperature.

The resulting adducts containing isocyanate groups are then reacted in a second step with an amine XIV or a mixture of such amines. This is advantageously done without isolating the intermediate of formula XV

R ¹ - [X-CO-NH-R ³ -NCO] ₀ (XV),

wherein R ¹ , R ³ , X and o have the meaning defined above.

This reaction also takes place in an organic solvent. Examples of this are listed above.

The starting products of the formulas XII, XIII and XIV are known and some are commercially available. Otherwise, these starting compounds can be obtained by standard reactions in organic chemistry.

In addition to the compounds of the

Formula I polyoxymethylene homo- or copolymers.

The polyoxymethylenes (POM), as described, for example, in DE-A 29 47 490, are generally unbranched linear polymers, which are generally at least 80%, preferably at least 90%,

Contain oxymethylene units (-CH2-O-). The term polyoxymethylene includes both homopolymers of formaldehyde or its cyclic oligomers, such as trioxane or tetroxane, as well as corresponding copolymers.

Homopolymers of formaldehyde or trioxane are those polymers whose

Hydroxyl end groups are chemically stabilized against degradation in a known manner, e.g. B. by esterification or by etherification. Copolymers are polymers of formaldehyde or its cyclic oligomers, especially trioxane, and cyclic ethers, cyclic acetals and / or linear polyacetals.

Such POM homopolymers or copolymers are known per se to the person skilled in the art and are described in the literature.

In general, these polymers have at least 50 mol% of recurring units -CH2-O- in the main polymer chain. The homopolymers are generally prepared by polymerizing formaldehyde or trioxane, preferably in the presence of suitable catalysts. In the compositions according to the invention, POM copolymers are preferred, in particular those which, in addition to the repeating units -CH ₂ -O-, also contain up to 50, preferably from 0.1 to 20 and in particular 0.5 to 10 mol% of repeating units

contain, where R to R independently of one another are a hydrogen atom, a Cr to C ₄ alkyl group or a halogen-substituted alkyl group having 1 to 4 C atoms and R ^{15 is} a -CH2-, -O-CH ₂ -, ad- to C ₄ alkyl or C ₄ to C - represent 4-substituted methylene group or a corresponding oxymethylene group, and n has a value in the range of 0 has up. 3

These groups can advantageously be introduced into the copolymers by ring opening of cyclic ethers. Preferred cyclic ethers are those of the formula

where R ¹¹ to R ¹⁵ and n have the meaning given above.

Examples include ethylene oxide, 1,2-propylene oxide, 1,2-butylene oxide,

1, 3-butylene oxide, 1, 3-dioxane, 1, 3-dioxolane and 1, 3-dioxepane as cyclic ethers and linear oligo- or polyformals, such as polydioxolane or polydioxepane, as comonomers.

Copolymers of 99.5-95 mol% of trioxane and 0.5 to 5 mol% of one of the aforementioned comonomers are used particularly advantageously.

Also suitable as polyoxymethylenes are oxymethylene terpolymers which, for example, by reacting trioxane, one of the cyclic ethers described above and with a third monomer, preferably a bifunctional compound of the formula

O ^ O

where Z is a chemical bond, -O- or -0-R ¹⁷ -O- (R = C ₂ - to C_ -alkylene or C- ₂ - to Cs-cycloalkylene) are produced.

Preferred monomers of this type are ethylene diglycide, diglycidyl ether and diether from glycidylene and formaldehyde, dioxane or trioxane in a molar ratio of 2: 1, and diether from 2 mol of glycidyl compound and 1 mol of an aliphatic diol having 2 to 8 carbon atoms, such as, for example, the diglycidyl ether of ethylene glycol , 1, 4-butanediol, 1,3-butanediol, cyclobutane-1,3-diol, 1,2-propanediol and cyclohexane-1,4-diol, to name just a few examples.

Processes for the preparation of the POM homo- and copolymers described above are known to the person skilled in the art and are described in the literature.

The preferred POM copolymers have melting points of at least 150 ° C. and molecular weights (weight average) M _w in the range from 5,000 to 200,000, preferably from 7,000 to 150,000.

End-group stabilized POM polymers which have C-C bonds or the methoxy end groups at the chain ends are particularly preferred.

The used POM-polymers generally have a melt index (MVR value 190/2, 16) of 2 to 50 cm ^3/10 min (ISO 1 133).

The compositions according to the invention usually contain 75 to 99.99% by weight, preferably 80 to 99.8% by weight, of POM homo- or copolymer and 0.01 to 5% by weight, preferably 0.2 to 0.5% by weight. % of compounds of the formulas I, these details relating in each case to the overall composition.

In addition to these components, the compositions according to the invention also contain other additives known per se.

Examples of this are processing aids such as antioxidants, acid scavengers and others

Formaldehyde scavengers, UV stabilizers, adhesion promoters, lubricants, nucleating agents or mold release agents; Fillers, such as glass balls, calcium carbonate, talc, wollastonite or silicon dioxide; Reinforcement materials such as carbon fibers, aramid fibers or glass fibers; Antistatic agents or additives which impart a desired property to the molding composition, such as dyes and / or pigments and / or

Impact modifiers and / or additives which impart electrical conductivity, for example carbon black or metal particles, and mixtures of these additives, but without restricting the scope to the examples mentioned. The proportion of these additives in the compositions according to the invention is usually 0.2 to 30% by weight, preferably 0.5 to 25% by weight, based on the total composition.

Examples of antioxidants are phenolic compounds, such as N, N'-bis-3- (3 ', 5'-di-tert-butyl-4 ^' -hydroxyphenyl) propionylhydrazine, 1, 6-hexanediol-bis-3- (3rd ^', ^5' -di- tert-butyl-4 ^{'hydroxyphenyl)} propionate, 3,6-dioxaoctane-1, 8-diol-bis-3- ^[3' -t-butyl-4 ^'- ^hydroxy-5' - (methylphenyl)] propionate, N, N ^' -hexamethylene-bis-3- (3 ^' , 5 ^' -di-tert.butyl- 4 ^' -hydroxyphenyl) propionamide, tetrakis [methylene-3- (3 ^' , 5 ^{'-di-tert-butyl-4'-hydroxyphenyl)} propionyl)] methane and 1, 3,5-trimethyl-2,4,6-tris ^(3', 5 ^{'-di-tert-butyl-} 4 ^{'hydroxybenzyl)} benzene.

Examples of lubricants are esters and amides of a long-chain aliphatic carboxylic acid and an aliphatic alcohol, or polyethylene waxes, preferably oxidized polyethylene waxes.

Examples of additives which give the molding composition a desired property are ultra-high molecular weight polyethylene (PE-UHMW), polytetrafluoroethylene (PTFE) and graft copolymers which are a product of a grafting reaction from an olefin

Polymer and an acrylonitrile / styrene copolymer.

Examples of impact modifiers are polyurethanes with elastomeric properties or other elastomers.

The following examples illustrate the invention without limiting it. Unless otherwise stated, quantities are always given in parts by weight.

General working instructions

The polyol was dissolved in DMSO. A solution of isophorone diisocyanate in DMSO was added dropwise at room temperature. After the addition, 5-10 drops were left of dibutyltin dilaurate was added and the reaction solution was stirred at room temperature for about 6 hours. After this, melamine was added and the reaction was stirred at 150 ° C. overnight.

The DMSO was separated off by distillation, the product was dried to constant weight at 120 ° C. and then finely ground.

The table below shows the reagents used and the yields obtained

table

Application Examples

The stabilizers thus produced were mixed in different concentrations in a POM with an MVR of 9 ml / 10 min and compared against melamine in their acceptor properties. In addition to the formaldehyde acceptors, other stabilizers were present (lubricants, oxidation stabilizers, acid scavengers), the type and amount of which were kept constant in all experiments. The formaldehyde emission was measured using the VDA 275 test. The results are shown in the table below. table

Claims

claims

1. Compositions containing at least one polyoxymethylene homo- and / or copolymer and 0.01 to 5% by weight of at least one compound of the formula I with a molecular weight of at least 800

R ¹ - [X-CO-NH-R ³ -NH-CO-NR ² -R ⁴ ] ₀ (I),

in which R ¹ denotes the di- to hexavalent radical of an alcohol or amine,

X is -O- or -NR ² -,

R ^{2 is} hydrogen, alkyl, cycloalkyl, aryl or aralkyl,

R ^{3 is} alkylene, cycloalkylene, arylene or aralkylene,

(VI), -HN-C (= NH) -NH-CN (VII),

wherein R ^{5 is} hydrogen, -CO-CH ₃ or -CO-C ₆ H ₅ , o is an integer between 2 and 6 and p is 1 or 2.

2. Compositions according to claim 1, characterized in that R ²

Is methyl or preferably hydrogen.

3. Compositions according to claim 1, characterized in that R ^{1 of} the radical having a di- to tetravalent hydroxyl or amino end group of a polyether, polyester, polyamide, polyacrylate, polyolefin, polysiloxane or

Polycarbonate after removal of the end groups.

4. Compositions according to claim 3, characterized in that R ^{1 is} the divalent to tetravalent hydroxyl or amino end group having a residue of a polyether or polyester after removal of the end groups, which has the recurring structural units of the formulas VIII, IX, X or XI

- [R ⁶ -O-] _x -R ⁶ - (VIII), R ⁷ - [[- OR ⁶ -] _x -] _p (IX),

- [R ⁸ -0-CO-R ⁹ -CO-0-] _y -R ⁸ - (X), R ¹⁰ - [[O-CO-R ⁹ -CO-OR ⁸ -] _y ] _p - (XI )

R ⁷ and R ^{10 are} residues of a di to tetravalent aliphatic, cycloaliphatic, aromatic or araliphatic alcohol, x and y represent integers from 1 to 200, and p is an integer from 2 to 4.

5. Compositions according to claim 4, characterized in that R ⁶ and R ^{8 are} radicals of the formula -CH ₂ -CH ₂ -, -CH (CH ₃ ) -CH- or -CH2-CH ₂ -CH2-CH ₂ -,

R ^{9 is} a radical of the formula -CmH ₂ m-, where m is an integer from 2 to 6, or a phenylene radical, and R ⁷ and R ^{10 are} radicals of the formula -C _n H ₂ n-, phenylene, Trimethylolpropane without the three hydroxyl groups or pentaerythritol without the four hydroxyl groups.

6. Compositions according to claim 1, characterized in that R ^{1 is} a radical of the formula -C _n H2 _n -, where n is an integer from 2 to 4, phenylene,

Trimethylolpropane without the three hydroxyl groups, pentaerythritol without the four hydroxyl groups, or a sugar without the six hydroxyl groups.

7. Compositions according to claim 1, characterized in that X is -NH- or in particular -O-.

8. Compositions according to claim 1, characterized in that R ^{3 is} a radical -C _p H ₂ p-, where p is an integer from 2 to 18, a divalent radical of a cycloalkylene having five to eight ring carbon atoms, a phenylene or naphthylene radical, these radicals being one to four

May have substituents which are selected from the group consisting of alkyl, alkoxy, cycloalkyl, cycloalkyloxy, aryl and aryloxy.

9. Compositions according to claim 8, characterized in that R ^{3 is} a divalent radical derived from 4-methylpentane, 5-methylhexane, 1-

Methylcyclohexane, 6-methylheptane, 2,2,5-trimethylheptane, 3,7-dimethyloctane, 1, 2,2-trimethylcyclopentane, 1, 4- or 1, 3-dimethylcyclohexane, toluene, biphenyl, diphenylmethane, dicyclohexylmethane, isophorone and is hexane.

10.Compositions according to claim 1, characterized in that R ⁴ a

Radical of formula V or in particular of formula II.

11. Compositions according to claim 8, characterized in that R ^{4 is} a radical of formula V or in particular of formula II and x and y are integers from 8 to 15.

^ .Compositions according to claim 1, characterized in that o is 2.

13. Compounds of formula I according to claim 1, wherein X, R ¹ , R ² , R ³ , R ⁴ , R ⁵ and o have the meanings defined in claim 1, with the proviso that when R ^{4 is} a radical of formula II , III, IV, VI or VII, R ^{1 is} the radical having a di- to tetravalent hydroxyl or amino end group of a polyether or polyester after removal of the end groups, which is the repeating structural units of the formulas VIII, IX, X or XI according to claim 4 and where the indices x, y and p assume values such that the compound of the formula I has a molecular weight of at least 800, preferably at least 800 to 5,000, particularly preferably from 850 to 2,200.

14. Use of the compound of formula I according to claim 1 for reducing the formaldehyde emission of polyoxymethylene homo- or copolymers.