EP1704184A1

EP1704184A1 - Polyoxymethylene molding compounds and use thereof

Info

Publication number: EP1704184A1
Application number: EP04816306A
Authority: EP
Inventors: Stefan Wulf; Klaus Kurz; Christine KÖSTLER
Original assignee: Ticona GmbH
Current assignee: Ticona GmbH
Priority date: 2003-12-18
Filing date: 2004-12-17
Publication date: 2006-09-27
Also published as: WO2005059030A1

Abstract

The invention relates to compositions containing: a) at least one polyoxymethylene homopolymer and/or copolymer, and; b) at least one ester wax containing at least one ester group derived from a carboxylic acid containing six to one hundred carbon atoms, and containing at least one primary, secondary or tertiary amino group and/or at least one heterocycle containing nitrogen, and/or containing amide waxes derived from aliphatic monoamines having six to twenty carbon atoms or from a heterocycle having nitrogen-containing amino groups and from a carboxylic acid containing six to one hundred carbon atoms. Component b) is suited for use as a formaldehyde scavenger in polyoxymethylene molding compounds.

Description

description

Polyoxymethylene molding compositions and their use

The present invention relates to new polyoxymethylene molding compositions with good internal sliding properties and low formaldehyde emissions.

Small amounts of formaldehyde are released during the manufacture and thermoplastic processing of polyoxymethylene compositions. 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 toxicity, it is 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 during the production and processing of polyoxymethylene molding compositions (hereinafter also referred to as “POM molding compositions”). Usually, so-called formaldehyde scavengers are used for this purpose. Such compounds often have primary and aromatically bound amino groups on that with the formaldehyde under

Formation of methylol groups react and thus remove them from the reaction system.

Typical formaldehyde scavengers for POM molding compositions are melamine, melamine-formaldehyde condensates (MFK), 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. Basically, therefore aiming for the highest possible amount of these additives. 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.

Typical lubricants are unmodified or oxidized polyolefin waxes or esters or amides of long-chain carboxylic acids. So far, ester waxes or amide waxes have been used. Typical representatives of these compounds are, for example, stearates or montanates which have been reacted with ethanediol, propanediol or ethylenediamine.

These compounds are so-called "internal lubricants", i.e. additives that are used in the POM molding composition, in contrast to "external lubricants", which e.g. are used as mold release agents and are used as coatings for molds.

The amount of additive added affects the emission of formaldehyde quantitatively. For this reason, the highest possible dosage of the formaldehyde scavenger has so far been sought. On the other hand, excessively high doses lead to the formation of mold deposits and / or undesirable ones

Surface effects, e.g. Streaking. A group of additives has now been found which simultaneously give the POM molding composition good sliding properties combined with the reduction in formaldehyde emissions. By using an additive with combined properties, it is possible to use it in higher doses without the formation of

Form coverings must be expected.

So far, the combination of properties mentioned above has been achieved by adding at least two additives. With the present invention, it is possible to achieve this combination of properties by adding only one additive.

POM molding compositions to which polyester amides have been added are also known. RU-A-2,039,772 describes casting compounds, the POM, branched Polycarbonate contains selected inorganic additives and ester amide wax. US-A-4,439,565 describes oligomeric polyester amides with sterically hindered amine side groups, which can be used as stabilizers against thermal or radiation-induced degradation in polymers. DE-A-1, 768,384 describes bis-oxalic acid ester amides as stabilizers for polymers. In the

GB-A-1, 165, 236 describes a process for stabilizing POM, in which inter alia formaldehyde acceptors, for example polyesteamides, are added. DE-A-10052 763 describes nucleated POM molding compositions with an increased crystallization rate. These can contain amides of long-chain fatty acids or bis-esters of long-chain fatty acids as lubricants.

The invention provides POM molding compositions which contain selected additives which on the one hand have nitrogen atoms with sufficient basicity so that the formaldehyde emission of the molding composition is reduced without other disadvantages for the POM, e.g. increased tendency to yellowing or formation of mold coverings, which also have residues derived from long-chain carboxylic acids, so that an additional sliding effect is imparted and thus the mechanical damage to the molten POM molding composition is reduced, which is one of the causes of the

Is formaldehyde emission.

The object of the present invention is to provide new POM molding compositions which, in addition to a low emission of formaldehyde during production and processing, have excellent sliding properties.

The present invention relates to compositions comprising a) at least one polyoxymethylene homo- and / or copolymer, and b) at least one ester wax containing at least one ester group derived from a carboxylic acid containing six to one hundred carbon atoms and at least one primary, secondary or tertiary amino group and / or at least a nitrogen-containing heterocycle and / or at least one amide wax derived from aliphatic monoamines having six to thirty carbon atoms or a heterocycle containing an amino group containing nitrogen and a carboxylic acid containing six to one hundred carbon atoms.

Component a) of the compositions according to the invention

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 (-CH ₂ -O-). The term polyoxy-methylene includes both homopolymers of formaldehyde or its cyclic oligomers, such as trioxane or tetroxane, and 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, in particular 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 -CH ₂ -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 ¹ to R ⁴ independently of one another are a hydrogen atom, a C to C ₄ alkyl group or a halogen-substituted alkyl group having 1 to 4 C atoms and R ^{5 is} a -CH2-, -O-CH ₂ -, ad- to C ₄ alkyl or C to C ₄ haloalkyl substituted methylene group or a corresponding oxymethylene group and n has a value in the range from 0 to 3.

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

formula

where R) 1 ¹ D R5 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, mentioned 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 wherein Z is a chemical bond, -O- or -OR ⁶ -O- (R ⁶ = C ₂ - to C ₈ -alkylene or C ₂ - to Cs-cycloalkylene).

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 homopolymers 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 at 190 ° C / 2, 16 kg) of 2 to 50 cm ^3/10 min (ISO 1133).

Component b) of the compositions according to the invention are ester waxes derived from at least one carboxylic acid containing six to one hundred carbon atoms, which by esterification of a mono- or polyvalent Alcohol containing at least one primary, secondary or tertiary amino group and / or by esterification of a mono- or polyhydric alcohol containing at least one nitrogen-containing heterocycle; or component b) is selected amide waxes with an amide group which are derived from aliphatic monoamines with six to twenty

Carbon atoms or from a nitrogen-containing heterocycle and from a carboxylic acid containing six to one hundred carbon atoms.

The carboxylic acids typically have one to two and in particular one

Carboxyl group and preferably eight to fifty, in particular twenty to thirty-five, carbon atoms.

The carboxylic acids can be aromatic, heterocyclic, araliphatic, cycloaliphatic or aliphatic, the heterocyclic, araliphatic, cycloaliphatic or aliphatic compounds also being unsaturated or, in particular, saturated. It is preferably aliphatic carboxylic acids, in particular saturated aliphatic carboxylic acids.

Preferred examples of carboxylic acids are lauric acid, myristic acid,

Palmitic acid, stearic acid, arachidic acid, behenic acid, oleic acid or in particular carboxylic acids derived from montan waxes.

The amino alcohols required for the preparation of component b) to be used according to the invention can be aromatic, heterocyclic, araliphatic, cycloaliphatic or aliphatic, the heterocyclic, araliphatic, cycloaliphatic or aliphatic compounds also being unsaturated, preferably ethylenically unsaturated, or in particular saturated. They are preferably aliphatic amino alcohols, in particular saturated aliphatic amino alcohols.

In addition, component b) containing nitrogen atoms and at least one alcohol group can be prepared Heterocycles are used. The heterocycles preferably have one nitrogen atom or two nitrogen atoms or one nitrogen atom and one oxygen atom. They are typically five- to seven-membered heterocycles that can be unsaturated or saturated.

Examples of suitable heterocyclic radicals are Pyrrolyi, oxazolyl, imidazolyl, isoxazolyl, pyrazolyl, oxadiazolyl, triazolyl, indolyl, isoindolyl, benzoxazolyl, benzimidazolyl, benzisoxazolyl, benzopyrazolyl, benzotriazolyl, carbazolyl, pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, triazinyl, quinolinyl, isoquinolinyl, quinoxalinyl , Quinazolinyl, cinnolinyl, naphthyridinyl, pyridopyrimidinyl, purinyl, pteridinyl,

4H-quinolizinyl, piperidinyl, pyrrolidinyl, tetrahydropyranyl, isoxazolidinyi, pyrrolidyl, piperidyl, piperazinyl, oxazolinyl, isoxazolinyl, oxazolidinyl, isoxazolidinyi and morpholinyl.

These heterocyclic residues are substituted and have at least one

Substituents with an alcohol group, preferably a methylol group or a 1-hydroxyethyl group.

Further examples of substituents are halogen, alkyl, alkoxy, hydroxyl, amino (unsubstituted, mono- or disubstituted), carboxyl, alkoxycarbonyl, alkylcarbonyl,

Haloalkyl and oxo. An example of a nitrogen-containing heterocyclic radical containing oxo groups is 2,5-dioxo-4-imidazolidinyl.

Heterocycles can also arise from the reaction of amino alcohols with long-chain carboxylic acids. For example, when implementing Tris

(hydroxymethyl) aminomethane with carboxylic acid diesters of 4,4-bis (hydroxymethyl) -Δ ² oxazoline.

The amino alcohols typically have two to fourteen carbon atoms, especially two to six carbon atoms. Examples of amino alcohols are 2-aminophenol, 4-amino-cyclohexanol, aminoethanol, diethanolamine, tris (hydroxymethyl) aminomethane, 3-amino-propanol or 4-amino-butanol.

The nitrogen-containing heterocycles can have several ring nitrogen atoms and / or hydroxy functionalities, preferably one to three hydroxyl groups and one or two ring nitrogen atoms.

The aliphatic amines required for the production of component b) to be used according to the invention can be unsaturated or, in particular, saturated.

The amines have six to twenty two carbon atoms, especially ten to eighteen carbon atoms.

Examples of amines are fatty amines (also called taigamines), laurylamine, myristylamine, palmitylamine, stearylamine, oleylamine, arachidylamine or behenylamine.

The heterocyclic aliphatic amines required for the production of component b) to be used according to the invention can be unsaturated or saturated.

Preferred components b) are compounds of the formulas I, II, III, IV, V and / or

VI

wherein R ¹⁰ , R ¹² and R ^{14 are} independently monovalent aliphatic, cycloaliphatic, heterocyclic, aromatic or araliphatic radicals having six to one hundred carbon atoms, or R ¹⁰ and R ¹² or R ¹⁰ and R ¹⁴ or R ¹² and R ¹⁴ together form a divalent aliphatic, cycloaliphatic, heterocyclic, aromatic or araliphatic radical with six to one hundred carbon atoms, R ⁹ , R ¹¹ , R ¹³ and R ⁶ independently of one another are divalent aliphatic, cycloaliphatic, heterocyclic, aromatic or araliphatic radicals,

R ^9a and R ^11a independently of one another are a covalent bond or divalent aliphatic, cycloaliphatic, heterocyclic, aromatic or araliphatic radicals, R ⁷ , R ⁸ , R ¹⁵ , R ¹⁷ and R ^{18 are} independently hydrogen or monovalent aliphatic, cycloaliphatic, heterocyclic, aromatic or araliphatic

Are leftovers, or

R ⁷ and R ⁸ or R ¹⁷ and R ¹⁸ or R ¹⁵ and R ¹⁸ together can form a saturated or unsaturated heterocycle containing at least one nitrogen atom, which may optionally have further ring hetero atoms, in particular a further nitrogen atom or oxygen atom, and

R ^{19 is} a monovalent aliphatic radical having six to thirty carbon atoms or a heterocyclic radical containing nitrogen.

If any radicals are alkyl, these are generally saturated alkyl radicals with one to one hundred 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, or the alkyl radicals can chain heteroatoms, such as

Have oxygen atoms or -NH groups.

Preferred R ¹⁰ , R ¹² and R ^{14 are} alkyl radicals having eight to fifty, in particular twenty to thirty-five, carbon atoms.

Preferred R ⁷ , R ⁸ , R ¹⁵ , R ¹⁷ and R ^{18 are} alkyl radicals having one to ten, in particular one to six, carbon atoms. As R ¹⁹ , alkyl radicals have six to twenty-two, preferably ten to eighteen, carbon atoms.

If any radicals are cycloalkyl, these are generally saturated but also unsaturated cycloalkyl radicals having five to eight, preferably five or six, ring carbon atoms, which may also have one or two ring heteroatoms, such as nitrogen, sulfur or oxygen, and, if appropriate, one or more alkylene chains can have. 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 mean aryl, these are generally aromatic hydrocarbon radicals with one or two aromatic nuclei.

If any radicals are heterocyclic radicals, these are saturated or unsaturated hydrocarbon radicals, including the aromatic hydrocarbon radicals, which can have one, two or three ring heteroatoms, such as nitrogen, sulfur or oxygen. Typically, there are two interconnected ring systems or preferably one ring system. Heterocycles containing nitrogen or nitrogen and oxygen are preferred.

The aryl radicals or heterocyclic 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.

The preferred aryl radical is phenyl. Preferred heterocyclic radicals are 4-methylene-Δ ² -oxazolinyl, 1, 3,5-triazinyl or 2,5-dioxy-4-imidazolidinyl.

If any radicals are aralkyl, 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, and which furthermore have at least one 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.

If any radicals mean divalent alkyl radicals (alkylene), these are generally saturated alkylene radicals having one 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 having preferably one to six carbon atoms, or halogen atoms, such as chlorine, or the alkylene radicals can have heteroatoms in the chain, such as oxygen atoms or -NH groups, or heterocyclic, aromatic or cycloaliphatic groups.

Alkylene radicals having one to ten carbon atoms are preferred. Methylene, ethylene or propylene are particularly preferred.

If any radicals mean divalent cycloalkyl radicals (cycloalkylene), these are generally saturated or unsaturated cycloalkylene radicals having five to eight, preferably five or six, ring carbon atoms, which may also have one or two ring heteroatoms, such as nitrogen, sulfur or Oxygen and optionally one or more alkylene chains.

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 mean divalent aryl radicals (arylene), these are generally aromatic hydrocarbon radicals with one or two aromatic nuclei.

If any radicals mean divalent heterocyclic radicals, they are divalent saturated or divalent unsaturated

Hydrocarbon residues, including aromatic hydrocarbon residues, which may have one, two or three ring heteroatoms such as nitrogen, sulfur or oxygen. Typically, there are two interconnected ring systems or preferably one ring system. Heterocycles containing nitrogen or nitrogen and oxygen are preferred.

The arylene radicals or heterocyclic 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.

Preferred are phenylene, especially 1, 3- and 1, 4-phenylene, ^{biphen-4,4'-diyl,} ^{diphenylmethane-4,4'-diyl,} naphthylene or especially 4,4-bis-methylene-Δ ² - and oxazolindiyl 1, 3,5-triazinediyl.

If any radicals mean divalent aralkyl radicals (aralkylene), these are generally aromatic hydrocarbon radicals with one or two aromatic nuclei, which may also have one or two ring heteroatoms, such as May have nitrogen, sulfur or oxygen and which furthermore 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.

Preferred components b) are derived from acids from montan waxes, in particular by reaction with amino alcohols, in particular with diethanolamine or with triethanolamine and / or with primary long-chain monoamines

Taigamines, or with nitrogen-containing heterocyclic amines and / or with heterocyclic polyols such as 4,4-bis (hydroxymethyl) -Δ ² -oxazoline have been converted into the corresponding amino group-containing esters.

Compositions in which R ¹⁰ , R ¹² and R ^{14 are} independently monovalent aliphatic radicals having ten to thirty-five carbon atoms, R ⁹ , R ¹¹ , R ¹³ and R ^{16 are} independently divalent aliphatic radicals having two to six carbon atoms, R ⁷ , R ⁸ , R ¹⁵ , R ¹⁷ and R ^{18 are} independently hydrogen or monovalent aliphatic radicals having one to six carbon atoms, or R ¹⁵ and R ¹⁸ together are a saturated or containing one nitrogen atom or two nitrogen atoms or one nitrogen atom and one oxygen atom form unsaturated heterocycle.

In addition, compositions are particularly preferred in which component b) has ester groups or amide groups which are derived from monovalent carboxylic acids having eight to thirty-five carbon atoms, in particular from lauric acid, palmitic acid, oleic acid, stearic acid, behenic acid or from acids from montan wax.

Compositions are particularly preferred in which component b) is derived from diethanolamine, from triethanolamine or from 4,4-bis (hydroxymethyl) -Δ ² - derived oxazoline, which are esterified with monovalent carboxylic acids with eight to thirty-five carbon atoms.

The invention further relates to the use of ester waxes containing at least one of six to one hundred carbon atoms

Carboxylic acid-derived ester group and at least one primary, secondary or tertiary amino group and / or at least one nitrogen-containing heterocycle and / or amide waxes derived from aliphatic monoamines having six to twenty carbon atoms or from a nitrogen-containing heterocycle and from one containing six to one hundred carbon atoms Carboxylic acid to reduce the formaldehyde emission of polyoxymethylene homo- or copolymers.

The components b) used according to the invention can be obtained by processes known per se by reacting amino alcohols of the formulas Ia to Va and / or primary amines of the formula Via with one or more mono- and / or dicarboxylic acids of the formulas X or XI

R ¹⁰ -COOH (X), HOOC-R ^{10 '} -COOH (XI)

wherein R ⁷ , R ⁸ , R ⁹ , R ^9a , R ¹⁰ , R ¹¹ , R ^11a , R ¹³ , R ¹⁵ , R ¹⁶ , R ¹⁷ , R ¹⁸ and R ^{19 have} the meaning defined above, wherein R ¹⁰ also R Can be ¹² or R ¹⁴ , and wherein R ^{10 is} a divalent aliphatic, cycloaliphatic, heterocyclic, aromatic or araliphatic radical having six to one hundred carbon atoms.

Instead of the free carboxylic acid (s) of the formulas X and XI, their ester- and amide-forming derivatives, such as their halides, anhydrides or esters, can also be used.

In the reaction, the compounds of the formulas X and / or XI are used in such an amount that the free alcohol groups of the compounds of the Formulas la to Va or the free amide group of the compound of the formula Via are each reacted by a carboxyl group or carboxyl derivative group of the compound of the formula X and / or XI.

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

The reaction is usually carried out in the presence of a catalyst of the ester and

Amide formation.

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 starting products of formulas la to via are known and some are commercially available. Otherwise, these starting compounds can be obtained by standard reactions in organic chemistry.

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

(Component a)) and 0.01 to 5% by weight, preferably 0.2 to 0.5% by weight of component b), these details each relating to the overall composition.

In addition to these constituents, the compositions according to the invention may 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, other lubricants, nucleating agents or mold release agents; Fillers, such as glass balls, calcium carbonate, talc, wollastonite or silicon dioxide; Reinforcing 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 conductivity carbon blacks or metal particles, and mixtures of these additives, but without restricting the scope to the limit the examples mentioned.

The proportion of these additives in the compositions according to the invention is usually 0.2 to 50% by weight, preferably 0.5 to 30% by weight, based on the total composition.

A preferred embodiment relates to compositions comprising, in addition to components a) and b), dyes and / or pigments.

Pigments are particularly preferably used, in particular titanium dioxide, very particularly preferably combined with carbon black.

The compositions according to the invention particularly preferably contain titanium dioxide with further inorganic and / or organic pigments.

The compositions according to the invention likewise particularly preferably contain titanium dioxide, carbon black and other inorganic and / or organic pigments.

The molding compositions colored according to the invention are distinguished by a surprisingly high stability against decomposition and release of formaldehyde during processing.

Inorganic and / or organic dyes and / or pigments can be used. Examples of inorganic pigments are iron oxide pigments, lead chromate pigments, ultramarine pigments, iron blue pigments, cobalt blue pigments, rutile pigments, in particular titanium dioxide, cadmium pigments, bismuth vanadate pigments, cerium sulfide pigments, complex inorganic colored pigments ( so-called

Mixed phase metal oxide pigments) and carbon blacks.

Examples of organic pigments are azo pigments such as monoazo yellow and mono orange pigments; Diazo pigments, ß-naphthol pigments, naphthol AS pigments, benzimidazolone pigments, diazo condensation pigments, metal complex pigments,

Isoindolinone and isoindoline pigments, polycyclic pigments such as phthalocyanine pigments, quinacridone pigments, perylene and perinone pigments; Thioindigo pigments, anthraquinone pigments such as anthrapyrimidine pigments, flavanthrone pigments, pyranthrone pigments and anthanthrone pigments; Dioxazine pigments, triaryl carbonium pigments, quinophthalone pigments and diketo-pyrrolo-pyrrole

Pigments.

These pigments can be used either individually or as a mixture or together with polymer-soluble dyes.

Examples of antioxidants are phenolic compounds, such as N, N ^' -bis-3- (3', 5 ^' -ditert.butyl-4 ^' -hydroxyphenyl) -propionylhydrazine, 1, 6-hexanediol-bis-3- (305 ^' -di-tert.butyl-4'-hydroxyphenyl) propionate, 3,6-dioxaoctane-1,8-diol-bis-3- [3 ^' -tert.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- (30 ^5' -di-tert butyl-4 ^{'-hydroxybenzyl).} -benzene.

Examples of further 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 that give the molding compound a desired property are ultra high molecular weight polyethylene (PE-UHMW), polytetrafluoroethylene (PTFE) and graft copolymers, which is a product of a graft reaction of an olefin polymer and an acrylonitrile / styrene copolymer.

Examples of impact modifiers are polyurethanes with elastomers

Properties, grafted polymers containing, in addition to non-polar, also polar polymer segments, for example styrene-acrylonitrile copolymer grafted onto polyethylene, such as LDPE-SAN as described in EP-A-354.802 and EP-A-420.564, or particularly preferably polymers with a core shell - Structure which have a rubber-elastic core based on polybutadiene and a hard shell, as described in EP-A-156,285 and EP-A-668,317.

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

Examples

Kneading experiments with a Brabender kneader to investigate the manufacture of POM multiblock copolymers and the investigation of formaldehyde emissions

VDA275 test.

Brabender kneading experiments

The starting materials (POM powder, antioxidant, hydrolysis stabilizer, optionally further stabilizers and internal lubricant: a total of 50 g) were compounded in an extruder and processed into granules. The housing temperature of the kneading chamber of a_Brabender PlastiCorder was set to 200 ° C and a hopper (accessory of the Brabender kneader) was placed on the kneading chamber. As soon as the housing temperature had reached 190 ° C, the kneader was running

(40 rpm) the granules (50 g in total) are filled into the funnel and then pressed into the kneading chamber by a displacer (wedge-shaped punch) with a bearing weight of 5 kg. The mixture started to melt and as soon as the When the melting process was completed (short-term drop in torque), the filling funnel was removed and instead the cover with the purge gas supply line and exhaust pipe was put on. The formaldehyde content of the exhaust gas was measured continuously and the experiment was ended after a total of 60 minutes (from filling the granulate mixture).

Formaldehyde emission according to VDA275

Panels with a wall thickness of 1 mm are made from the POM molding compounds. After a storage period of 24 h, the formaldehyde emission from the plates became

VDA 275 determined (VDA recommendation no.275, Automotive Engineering Documentation July 1994).

Test specimen production: The polyacetal granules were injection-molded into platelets with the dimensions 80 * 50 * 1 mm. An Kraus Maffei injection molding machine

KM 120 / 340B was used with the following injection molding parameters:

Melt temperature 195 ° C, flow front speed 200 mm / s, mold wall temperature 85 ° C, holding pressure 900 bar, holding pressure time 30 s, cooling time 10 s, back pressure 0 to 10 bar.

Before the test, the test specimens were stored for 24 hours in a standard climatic cabinet at 23 ° C and 50 relative air humidity.

Test: Two test specimens were hung in a 1 liter glass bottle over 50 ml of electric water on a stainless steel hook and stored for 3 hours in a forced-air drying cabinet at 60 ° C. The test specimens were removed from the test bottle. 5 ml of sample solution were pipetted into a test tube, the test tube was annealed at 95 ° C. for 10 minutes. Now 3 ml of acetylacetone and 3 ml of a 20% ammonium acetate solution were added to the test tube. With the reagents, the formaldehyde formed the diacetyldihydrolutidine complex, the absorption of which was determined photometrically at 412 nm. The formaldehyde concentration in the sample solution was calculated from the absorption. The type Hostaform ^® C9021 (copolymer 1, Ticona GmbH) was used as the POM in one test series, the type C27021 (copolymer 2, Ticona GmbH) in a second test series, and the type T1020 (terpolymer, Ticona GmbH) in a third test series. Irganox 245 (CIBA) was used as an antioxidant in all test series and tricalcium citrate was used as a hydrolysis stabilizer. Type C27021 was a pigmented product, while the other two types were unpigmented. The table below shows the type and amount of the internal lubricant used, the melt flow index of the granulate, the amount of formaldehyde released during Brabender degradation and the formaldehyde emission of the POM molding compound determined in accordance with VDA 275.

Table: Test results

⁾ Licowax C is an amide wax with two amide groups based on ethylenediamine and stearic acid (Clariant GmbH); NC 133 is an ester amide wax derived from diethanolamine and acids from montan waxes (Clariant GmbH); FH-G 370 is an amide wax derived from taigamines and acids from montan waxes with an amide group (Clariant GmbH); FH-G 408 is an ester wax (Clariant GmbH) derived from 4,4-bis (hydroxymethyl) -Δ ² oxazoline and acids from montan waxes; FH-R 227 is an ester wax derived from triethanolamine and acids from montan waxes (Clariant GmbH)

²⁾ MVR at 2.16 kg and 190 ° C. The results shown in the table show that the molding compositions according to the invention have a significantly reduced release of formaldehyde.

Claims

claims

1. Compositions containing a) at least one polyoxymethylene homo- and / or copolymer, and b) at least one ester wax containing at least one ester group derived from a carboxylic acid containing six to one hundred carbon atoms and at least one primary, secondary or tertiary amino group and / or at least one nitrogen containing heterocycle and / or at least one amide wax derived from aliphatic monoamines having six to thirty carbon atoms or from a heterocycle containing nitrogen groups and from a carboxylic acid containing six to one hundred carbon atoms.

2. Compositions according to claim 1, characterized in that the polyoxymethylene homo- and / or copolymer has a melting point of at least 150 ° C and a molecular weight (weight average) M _w in the range from 5,000 to 200,000, preferably from 7,000 to 150,000.

3. Compositions according to claim 1, characterized in that the polyoxymethylene homo- and / or copolymer is end group stabilized and has C-C bonds or methoxy end groups at the chain ends.

4. Compositions according to one or more of claims 1 to 3, characterized in that component b) is a compound of the formulas I and / or II and / or III and / or IV and / or V and / or VI

wherein R ¹⁰ , R ¹² and R ^{14 are} independently monovalent aliphatic, cycloaliphatic, heterocyclic, aromatic or araliphatic radicals having six to one hundred carbon atoms, or R ¹⁰ and R ¹² or R ¹⁰ and R ¹⁴ or R ¹² and R ¹⁴ together form one divalent aliphatic, cycloaliphatic, heterocyclic, aromatic or araliphatic radical having six to one hundred carbon atoms, R ⁹ , R ¹¹ , R ¹³ and R ¹⁶ independently of one another are divalent aliphatic, cycloaliphatic, heterocyclic, aromatic or araliphatic radicals, R ^9a and R ^{11a are} independent of one another are a covalent bond or divalent aliphatic, cycloaliphatic, heterocyclic, aromatic or araliphatic radicals, R ⁷ , R ⁸ , R ¹⁵ , R ¹⁷ and R ¹⁸ independently of one another are hydrogen or monovalent aliphatic, cycloaliphatic, heterocyclic, aromatic or araliphatic radicals, or R ⁷ and R ⁸ or R ¹⁷ and R ¹⁸ or R ¹⁵ and R ¹⁸ together can form a saturated or unsaturated heterocycle containing at least one nitrogen atom, independently of one another are monovalent aliphatic, cycloaliphatic, heterocyclic, aromatic or araliphatic radicals, and R ^{19 is} a monovalent aliphatic radical having six to thirty carbon atoms or a nitrogen-containing heterocyclic radical.

5. Compositions according to claim 4, characterized in that R ¹⁰ , R ¹² and R ^{14 are} independently monovalent aliphatic radicals having ten to thirty-five carbon atoms, R ⁹ , R ¹¹ , R ¹³ and R ^{16 are} independently divalent aliphatic radicals having two to are six carbon atoms, R ⁷ , R ⁸ , R ¹⁵ , R ¹⁷ and R ^{18 are} independently hydrogen or monovalent aliphatic radicals having one to six carbon atoms, or R ¹⁵ and R ¹⁸ together are one nitrogen atom or two nitrogen atoms or one nitrogen atom and one Form oxygen atom-containing saturated or unsaturated heterocycle.

6. Compositions according to claim 1, characterized in that component b) has ester groups or amide groups which are derived from monovalent carboxylic acids having eight to thirty-five carbon atoms, in particular from lauric acid, palmitic acid, oleic acid, stearic acid, behenic acid or from acids from montan wax.

7. Compositions according to claim 1, characterized in that component b) is derived from diethanolamine, from triethanolamine or from 4,4-bis (hydroxymethyl) -Δ ² oxazoline, which are esterified with monovalent carboxylic acids having eight to thirty-five carbon atoms.

8. Compositions according to claim 1, characterized in that they contain dyes and / or pigments in addition to components a) and b).

9. Compositions according to claim 8, characterized in that they contain inorganic pigments, in particular iron oxide pigments, lead chromate pigments, ultramarine pigments, iron blue pigments, cobalt blue pigments, rutile pigments, in particular titanium dioxide, cadmium pigments, bismuth vanadate. Pigments, cerium sulfide pigments, complex inorganic colored pigments (so-called mixed-phase metal oxide pigments), carbon blacks or combinations of one or more thereof.

10. Compositions according to claim 8, characterized in that they contain organic pigments, in particular azo pigments, diazo pigments, β-naphthol pigments, naphthol AS pigments, benzimidazolone pigments, diazo condensation pigments, metal complex pigments, isoindolinone pigments. and isoindoline pigments, polycyclic pigments, thioindigo pigments, anthraquinone pigments, dioxazine pigments, triaryl carbonium pigments, quinophthalone pigments, diketo-pyrrolo-pyrrole pigments or combinations of one or more thereof.

1 1. Compositions according to claim 8, characterized in that they contain titanium dioxide, especially in combination with carbon black.

12. Compositions according to claim 11, characterized in that they contain further inorganic and / or organic pigments.

13. Compositions according to claim 10, characterized in that these as polycyclic pigments phthalocyanine pigments, quinacridone pigments, perylene pigments and / or perinone pigments or as anthraquinone pigments, anthrapyrimidine pigments, flavanthrone pigments, pyranthrone pigments and / or contain anthanthron pigments.

14. Use of ester wax containing at least one ester group derived from a carboxylic acid containing six to one hundred carbon atoms and at least one primary, secondary or tertiary amino group and / or at least one nitrogen-containing heterocycle and / or amide waxes derived from aliphatic monoamines having six to twenty carbon atoms or of a heterocycle containing an amino group and of a carboxylic acid containing six to one hundred carbon atoms to reduce the formaldehyde emission of polyoxymethylene homo- or copolymers.