DE10238518A1 - Wear-resistant polyoxymethylene molding compounds and their use - Google Patents

Abstract

Polyoxymethylene molding compositions are described which contain at least one graft copolymer which has an olefin polymer as the graft base and grafted thereon at least one vinyl polymer or an ether polymer, and / or a graft copolymer which comprises a rubber-elastic core based on polydiene and a hard graft shell (Meth) acrylates and / or (meth) acrylonitrile or styrene and at least one (meth) acrylate and / or (meth) acrylonitrile, and at least one lubricant selected from the group consisting of silicone oils with a molecular weight (weight average) of at least 20,000 oils derived from alpha-olefins, from polyolefin waxes, from alkyl esters of carboxylic acids with ten to one hundred carbon atoms or combinations of these lubricants. DOLLAR A The compositions are particularly suitable as a thermoplastic molding composition for injection molding and extrusion for the production of moldings of all kinds, in particular for functional components for which low abrasion and low coefficients of friction are required.

Description

The present invention relates to new polyoxymethylene molding compositions and their use, in particular as a molding compound for Injection molding and extrusion for the production of moldings of any kind Kind, especially for Functional parts, for the low abrasion and low coefficient of friction are required.

Polyoxymethylene (hereinafter also as "POM" has good tribological properties. With blends different POM types is usually strong due to the polar character of the polymers, a sliding modification is required. It is important that modifiers are selected which weaken the strongly polar properties of POM. For this A number of non-polar polymers have already been used for this purpose such as polytetrafluoroethylene, polyethylene or polyethylene ultra high molecular weight.

There are also already grafted polymers have been used, which in addition to non-polar and polar polymer segments exhibit. A preferred representative of this type is one on polyethylene grafted styrene-acrylonitrile copolymer, e.g. LDPE SAN. compositions containing POM and such additives are described in EP-A-354,802 and in EP-A-420,564. There is also the addition of lubricants and other substances disclosed.

Another type of grafted polymer which are used as additives in POM molding compounds are polymers with core-shell structure, which has a rubber-elastic core based on polybutadiene and have a hard coat. Such additives are described in EP-A-156,285 and EP-A-668,317.

It is also known that the abrasion resistance of impact resistant modified POM molding compounds by adding lubricants can be improved. However, tests have shown that this statement must not be generalized, but that it depends on the combination of additives used. For example found that combinations of POM with LDPE-SAN and mineral oils, as well fluorinated synthetic oils are not or only poorly compatible with each other and no improvement wear resistance the molded parts formed from the molding composition compared to unmodified POM is found.

POM molding compounds have now been found, the selected one Combinations of additives included and which is a significant improvement in wear resistance of the molded parts formed therefrom.

The present invention relates to Containing compositions

• a) at least one polyoxymethylene homide / or copolymerizate,
• b) at least one graft copolymer which is an olefin polymer Graft base and grafted on at least one vinyl polymer or comprises an ether polymer and / or a graft copolymer which a rubber-elastic core based on polydiene and one hard graft cover from (meth) acrylates and / or (meth) acrylonitrile or from styrene and has at least one (meth) acrylate and / or (meth) acrylonitrile, and
• c) at least one lubricant selected from the group consisting of from silicone oils with a weight average molecular weight of at least 20,000, oils derived from alpha olefins, of polyolefin waxes, of alkyl esters of carboxylic acids ten to one hundred carbon atoms or combinations of these Lubricant.

The compositions of the invention have as component a) polyoxymethylene homo- or copolymers.

In the case of the polyoxymethylenes (“POM”), as described, for example, in DE-A-2,947,490 are described, in general are unbranched linear polymers which generally contain at least 80%, preferably at least 90%, oxymethylene units (-CH ₂ -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 Trioxans are those polymers whose hydroxyl end groups are known Are chemically stabilized against degradation, e.g. B. by esterification or by etherification. Copolymers are polymers made from 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.

wobei R¹ bis R⁴ unabhängig voneinander ein Wasserstoffatom, eine C₁- bis Ca-Alkylgruppe oder eine halogensubstituierte Alkylgruppe mit 1 bis 4 C-Atomen und R⁵ eine -CH2-, -O-CH₂-, eine C₁- bis C₄-Alkyl- oder C₁- bis C₄-4-Haloalkyl substituierte Methylengruppe oder eine entsprechende Oxymethylengruppe darstellen und n einen Wert im Bereich von 0 bis 3 hat.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-, up to 50, preferably from 0.1 to 20 and in particular 0.5 to 10 mol% of repeating units of the contain the following formula,

wherein R ¹ to R ⁴ independently of one another are a hydrogen atom, a C ₁ - to Ca-alkyl group or a halogen-substituted alkyl group with 1 to 4 C-atoms and R ^{5 is} a -CH2-, -O-CH ₂ -, a C ₁ - bis C ₄ alkyl or C ₁ to C ₄ -4 haloalkyl substituted methylene group or a corresponding oxymethylene group and n has a value in the range from 0 to 3.

wobei R¹ bis R⁵ und n die obengenannte Bedeutung haben.These groups can advantageously be introduced into the copolymers by ring opening of cyclic ethers. Preferred cyclic ethers are those of the formula below

where R ¹ to R ⁵ 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 are particularly advantageous from 99.5 - 95 Mol% trioxane and 0.5 to 5 mol% of one of the aforementioned comonomers used.

wobei Z eine chemische Bindung, -O- oder -O-R⁶-O-(R⁶ = C₂- bis C₈-Alkylen oder C₂- bis C₈-Cycloalkylen) ist, hergestellt werden.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

where Z is a chemical bond, -O- or -OR ⁶ -O- (R ⁶ = C ₂ - to C ₈ -alkylene or C ₂ - to C ₈ -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 2: 1, and Diether from 2 moles of glycidyl compound and 1 mole of one aliphatic diols with 2 to 8 carbon atoms, such as Diglycidyl ether of ethylene glycol, 1,4-butanediol, 1,3-butanediol, Cyclobutane-1,3-diol, 1,2-propanediol and cyclohexane-1,4-diol just to name a few examples.

Process for the preparation of the above POM homopolymers and copolymers described are known to the person skilled in the art and 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 at the chain ends become special prefers.

The used POM-polymers generally have a melt index (MVR value 190/2, 16, ISO 1133) of 1 to 50 cm ^3/10 min.

The compositions according to the invention usually contain 40 to 98% by weight, preferably 60 to 95% by weight, of POM homo- or Copolymer and 2 to 60% by weight, preferably 5 to 40% by weight Compounds of the formula I, these details being based on get the total composition.

The graft copolymers of component b) are described in EP-A-354,802 and EP-A-420,564 or in EP-A-156,285 and EP-A-668,317, the disclosure of which is expressly incorporated herein by reference becomes.

As a graft base for the graft copolymers of the first type are basically all olefin polymers or olefin copolymers.

Examples include homopolymers of alpha olefins, such as. Polyethylene, polypropylene or polybutylene, with polyethylene as low-density polyethylene (LDPE), as linear low-density polyethylene (LLDPE) or as high-density polyethylene (HDPE) may be present.

Other examples are copolymers, the main one of alpha-olefins and other ethylenically copolymerizable therewith unsaturated Monmeren are derived, such as with other alpha-olefins, alpha-beta-ethylenic unsaturated carboxylic acids or their derivatives, such as their glycidyl esters. Examples of such Copolymers are ethylene-propylene copolymers, ethylene-1-butene copolymers, Copolymers derived from ethylene and glycidyl acrylate or glycidyl methacrylate.

Suitable graft monomers are Principle all ethylenically unsaturated Monomers with polar groups or other graftable monomers with polar groups which are the polarity of the substantially non-polar Modify the graft base.

Examples of graft monomers are ethylenic unsaturated Carboxylic acids, like acrylic acid or methacrylic acid, and their derivatives, such as their esters, nitriles or amides, preferably their alkyl esters or nitriles, optionally in combination with other polar or non-polar comonomers, such as acrylonitrile or Combination of styrene with acrylonitrile; or polyethers such as polyalkylene glycols.

A graft copolymer is particularly preferred based on polyethylene or polypropylene grafted with acrylonitrile or with styrene / acrylonitrile.

Such products are known per se and commercially available. An example for is the product Modiper A 1401 from NOF Corporation, Tokyo, Japan.

As a graft base for the graft copolymers of the second type are basically all elastomers that form the rubber-elastic core.

Under the term "elastomer" is a polymer with rubber-elastic behavior in the context of this description to understand.

Examples of elastomers are acrylate rubber (ACM), polyester urethane rubber (AU), brominated butyl rubber (BIIR), polybutadiene (BR), polyisoprene, chlorinated butyl rubber (CIIR), chlorinated polyethylene (CM), Epichlorohydrin homopolymer (CO), polychloroprene (CR), sulfurized Polyethylene (CSM), ethylene-acrylate rubber (EAM), epichlorohydrin _ Copolymers (ECO), ethylene-propylene copolymers, sulfur cross-linked or peroxide cross-linked (EPDM / S, EPDM / P and EPM / P), polyether-urethane rubber (EU), ethylene-vinyl acetate copolymer (EVM), fluorine rubber (FKM), fluorosilicone rubber (FVMQ), hydrogenated Nitrile rubber (H-NBR), butyl rubber (IIR), vinyl-containing Dimethylpolysiloxane (MVQ), nitrile rubber (NBR) natural rubber (NR, IR), thioplastics (OT), polyfluorophosphazenes (PNF), polynorbornene (PNR), styrene-butadiene rubber (SBR) and carboxy-containing nitrile rubber (X-NBR).

Preferred graft bases for the graft copolymers of the second type for forming the rubber elastic core Polybutadiene, polyisoprene and / or polybutadiene / polystyrene.

Suitable graft monomers are Principle all ethylenically unsaturated Monomers which cover the rubber-elastic core with a non-rubber-elastic Modify the shell. These are preferably ethylenically unsaturated monomers with polar groups, as already mentioned above for the production of the component b) enumerated of the first type and / or non-polar ethylenically unsaturated monomers such as styrene.

Preferred examples of graft monomers are ethylenically unsaturated Carboxylic acids, like acrylic acid or methacrylic acid, and their derivatives, such as their alkyl esters with monohydric alcohols with one to ten carbon atoms, for example methyl, ethyl Propyl or butyl acrylate or the corresponding methacrylate; or Vinyl esters such as vinyl acetate; or vinyl ethers, such as vinyl methyl ether; or N-vinyl pyrrolidone; or non-polar ethylenically unsaturated monomers, like styrene.

Graft copolymers are particularly preferred based on polybutadiene and a two-shell graft shell Polystyrene and polymethacrylate.

Such products are known per se and commercially available. An example for is the product Paraloid EXL 2600 from Rohm and Haas Germany GmbH, Frankfurt am Main.

The proportion of component b) in the compositions according to the invention is usually 5 up to 50% by weight, preferably 8 to 30% by weight, based on the total composition.

As a lubricant or lubricant Combinations of component c) are suitable with a silicone oil Molecular weight (weight average) of at least 20,000, of alpha olefins derived oils, Polyolefin waxes, alkyl esters of carboxylic acids with ten to one hundred Carbon atoms or combinations of these lubricants.

In the case of silicone oils, all polysiloxanes that are liquid at room temperature (25 ° C.) can be used, provided that they have a weight average molecular weight of at least 20,000, preferably at least 25,000 and very particularly preferably from 25,000 to 300,000. In the molecular weight an For the purposes of this description, the silicone oils are values which have been obtained by gel permeation chromatography.

Typical viscosities of these oils at 25 ° C are in the range of 500 to 300,000 mm ² / s.

It is particularly preferred dialkyl polysiloxanes, especially dimethyl polysiloxanes. Products of this type are, for example, known as silicone oils AK (Wacker Chemistry) in retail.

As oils derived from alpha olefins, everyone can at room temperature (25 ° C) liquid Polyolefin homo- or copolymers or polyolefin homo- or co-oligomers are used.

Such oils generally have molecular weights less than 5,000 (number average), preferably from 100 to 4,000 and most preferably from 500 to 3,000. With the molecular weight information for these oils in mind This description is about values based on viscosity measurements Japanese Industry Standards JISK 2283 have been obtained. typical viscosities of these oils be at 100 ° C in the range of 10 to 2,000 cSt.

Examples of such oils are Homopolymers or oligomers based on alpha-olefins, e.g. derived from ethylene, propylene or butylene; or in particular Copolymers or oligomers based on different alpha-olefins, such as. derived from ethylene and at least one monomer selected from the group consisting of propylene, butylene, pent-1-ene, hex-1-ene, Oct-1's, Dec-1's, or combinations of one or more of these Comonomers.

It is particularly preferred co-oligomers derived from ethylene and propylene or from ethylene and butylene with a number average molecular weight of 500 to 4000.

Products of this type are commercially available, for example, under the name Lucant ^R (Mitsui Petrochemical).

The use of polyolefin waxes and / or of alkyl esters of carboxylic acids with ten to one hundred Carbon atoms or combinations of these lubricants in POM molding compositions is already known.

This is how WO-A-01 / 96,470 describes it POM molding compounds that have a combination of these lubricants. Reference is expressly made to the disclosure of this document.

Polyethylene waxes are mainly used as polyolefin waxes used. This can be non-polar, i.e. unmodified Are polyethylene waxes or preferably oxidized polyethylene waxes, which have polar groups, such as carboxyl groups or alcohol groups.

Polyethylene waxes commonly used have a density of 0.92 to 0.98 g / cm ³ and a dropping point of 100 to 145 ° C, and a viscosity number at 140 ° C of 100 to 100,000 mPa * sec (measured according to DGF-M- III 8).

Preferred oxidized polyethylene waxes are high molecular polar waxes. These usually point an acid number from 5 to 25 mg KOH / g and a viscosity at 140 ° C from 3,000 to 100,000 mPa * sec on (measured according to DGF-M-III 8; DGF standard methods can vary from from the Wissenschaftliche Verlagsgesellschaft mbH in Stuttgart become).

As an alkyl ester of carboxylic acids with The esters of one or two can have ten to one hundred carbon atoms polyhydric alcohols with mono- or polyhydric carboxylic acids for Come into play.

Examples of alcohols are monohydric Alcohols with one to twenty carbon atoms, such as methanol, ethanol, Propanol, isopropanol, butanol, pentanol, hexanol, heptanol, octanol, Nonanol, decanol, stearic alcohol or behenyl alcohol; or divalent Alcohols with two to ten carbon atoms, such as ethylene glycol, propylene glycol or butylene glycol; or trihydric alcohols, with three to ten Carbon atoms such as glycerin or trimethylolpropane; or tetravalent Alcohols with four to ten carbon atoms, such as pentaerythritol; or hexavalent alcohols with four to eight carbon atoms, such as sorbitol or mannitol.

Examples of monovalent carboxylic acids are carboxylic acids with ten to forty carbon atoms, such as lauric acid, palmitic acid, stearic acid, behenic acid or Montan acids.

Ester waxes, stearyl stearate, Behenyl behenate, isostearyl stearate, glycerol monostearate, glycerol monoisostearate, Glycerol distearate, pentaerythritol tereastearate, pentaerythritol tetrabehenate, Montansäureester and partially saponified montanic acid esters or their combinations in any mixing ratio used.

The proportion of component c) in the compositions according to the invention is usually 0.1 to 8% by weight, preferably 0.5 to 6% by weight, based on the total composition.

When using the lubricants of component c), what is not self-evident in this category of products has surprisingly been found to be sufficiently well tolerated by the other components of the composition. Low wear values and good sliding properties are achieved with the lubricants of component c). By adding component b), the polar POM is somewhat less polar. The consequence of this is that the usual adhesion forces are reduced when POM is paired with POM, and thus there is less wear. The combination of components b) and c) further reduce the abrasion of the molding compound and improve the already good sliding behavior of each individual component. The compositions according to the invention have clear plans parts in comparison to products highly filled with tribological fillers, such as calcium carbonate or with PTFE powder.

When using the at room temperature liquid but high molecular weight Silicone oils has about it also highlighted that in processing and application of the molding compounds with increased Temperatures due to the relatively high vapor pressure of the silicone oil only one low volatility of the lubricant can be determined. So are these oils at room temperature nonvolatile and also at 200 ° C is a volatility of below 1% (weight loss in% with a sample of 5 g in a porcelain crucible after heating for two hours at 230 ° C).

The additions of component c) have generally a more or less bad affinity for POM on so that when injection molding with a segregation and / or a splicing would have to be expected in the finished component. Surprisingly has in the compositions of the invention good tolerance of the components highlighted together. That behavior is particularly good when using oils pronounced, derived from alpha olefins.

Compositions are preferred wherein component b) is a graft copolymer is an ethylene polymer as a graft base and grafted onto it Stryrene acrylonitrile or styrene methacrylate.

Compositions are particularly preferred, wherein component b) is a graft copolymer which is an ethylene polymer as a graft base and grafted onto it, stryrene-acrylonitrile or Has styrene methacrylate and wherein component c) is one of alpha-olefins derived oil or where component c) is a combination of a polyolefin wax with an alkyl ester of a carboxylic acid containing ten to one hundred Is carbon atoms.

Compositions are very particularly preferred, wherein component b) is a graft copolymer which is an ethylene polymer as a graft base and grafted onto it, stryrene-acrylonitrile or Styrene methacrylate and wherein component c) is a combination an oil derived from alpha olefins with a polyolefin wax and an alkyl ester of a carboxylic acid of ten to one hundred Is carbon atoms. These combinations are characterized by a particularly high abrasion resistance.

Other preferred compositions contain as component b) a graft copolymer which has a rubber-elastic Core based on polybutadiene and / or polyisoprene and / or polybutadiene / styrene owns and that and a hard graft cover made of styrene and methacrylate having.

Compositions are particularly preferred, wherein component b) is a graft copolymer which has a rubber elastic Core based on polybutadiene and / or polyisoprene and / or polybutadiene / styrene owns and that and a hard graft cover made of styrene and methacrylate and wherein component c) is a silicone oil with a molecular weight (Weight average) of at least 20,000 or a combination a polyolefin wax with an alkyl ester of a carboxylic acid is ten to one hundred carbon atoms or one of alpha olefins derived oil is.

Compositions are very particularly preferred, wherein component b) is a graft copolymer which has a rubber elastic Core based on polybutadiene and / or polyisoprene and / or polybutadiene / styrene owns and that and a hard graft cover made of styrene and methacrylate and wherein component c) is a combination of one of alpha olefins derived oil with a polyolefin wax and an alkyl ester of a carboxylic acid is ten to one hundred carbon atoms. Draw these combinations is also characterized by a particularly high abrasion resistance. By component b) is additional high toughness achieved.

In addition to the components listed above contain the compositions according to the invention in usually other additives known per se.

Examples of this are processing aids, such as antioxidants, acid scavengers, formaldehyde scavengers, UV stabilizers, Adhesion promoter, other lubricants, nucleating agents or mold release agents, Fillers, reinforcing materials or antistatic agents; or additives, which give the molding compound a desired property, such as dyes and / or pigments and / or other impact modifiers and / or electrical conductivity mediating additives; as well as mixtures of these additives, without, however, restricting the scope to the examples mentioned.

The proportion of these additives in the compositions according to the invention is usually 0.01 to 60% by weight, preferably 0.01 to 40% 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) propionyl hydrazine, 1,6-hexanediol-bis-3- (3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) propionate, 3,6-dioxaoctane-l, 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 (3 ', 5'-di-tert-butyl-4'-hydroxybenzyl) benzene.

Examples of acid scavengers and / or formaldehyde scavengers are compounds of various types which can chemically bind split-off formaldehyde and thus prevent its possible oxidation to formic acid and / or which act as proton acceptors. Examples of such compounds are polyhydroxy compounds, urea and its substitution products, condensation products of urea derivatives, Amides, low-melting polyamides, high-melting polyamides dispersed in a carrier, melamine-formaldehyde condensation products, amines and other nitrogen-containing compounds, salts of carboxylic acids and alkaline earth oxides.

Examples of UV stabilizers, the POM Stabilize against photooxidative degradation are UV absorbers or sterically hindered amines (HALS stabilizers). examples for UV absorbers are benzophenone derivatives, such as 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-alkoxybenzophenones with n-octyl, iso-octyl or dodecyl as the alkyl group; benzotriazole, such as 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-5'-tert.octylphenyl) benzotriazole, 2- (2'-Hydroxy-3 ', 5'-di-tert-amylphenyl) benzotriazole, 2- (2'-Hydroxy-3', 5'-di- {2 '' - phenyl} -iso propylphenyl) benzotriazole, or 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) -5-chlorobenzotriazole; 2-ethylhexyl-2-cyano-3,3'-diphenylacrylate; Benzoates, such as p-butylphenyl salicylate, n-hexadecyl-3,5-di-tert-butyl-4-hydroxybenzoate; Oxanilides, such as N- (2-ethylphenyl) -N '- (2-ethoxy-5-tert-butylphenyl) oxalamide, 2-ethyl-2'-ethoxyoxanilide; UV-absorbing pigments such as carbon black or titanium dioxide; or HALS stabilizers, such as 4-acetoxy-2,2,6,6-tetramethylpiperidine, 4-stearoyloxy-2,2,6,6-tetramethylpiperidine, 4- (phenylcarbamoyloxy) -2,2,6,6-tetramethylpiperidine, Bis (2,2,6,6-tetramethylpiperidyl) succinate, bis (2,2,6,6-tetramethylpiperidyl) sebacate, Bis (2,2,6,6-tetramethyl-4-piperidyl) hexamethylene-1,6-dicarbamate, Tris (2,2,6,6-tetramethyl-4-piperidyl) benzene-1,3,5-tricarboxylate and polycondensates from dimethyl succinate and 1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine.

Examples of adhesion promoters are connections, which enable or improve the adhesion of the phases to one another. Examples for such Compounds can be found in EP-B-629,659.

Examples of lubricants are alkali or alkaline earth metal salts of long chain carboxylic acids, e.g. Calcium or magnesium stearate.

Examples of nucleating agents are compounds which promote the creation of a fine and more even structure of the POM, thereby the mechanical strength properties of the moldings increase. Moreover often allow nucleated POM molding compounds to be used earlier Demolding, that is a shortening the cycle times in injection molding processing. Examples of nucleating agents are talc, boron nitride, 2,3-dioxyquinoxaline, branched and cross-linked Acetal copolymers, acetal block copolymers and special melamine-formaldehyde resins.

Examples of other lubricants and mold release agents are salts of montanic acids, Salts of fatty acids, fatty alcohols, N, N '- (bis-stearyol) ethylenediamine or cis-erucic acid amide.

Examples of fillers are glass balls, calcium carbonate, Talc, wollastonite, zinc oxide or silicon dioxide.

Examples of reinforcement materials are carbon fibers, Aramid fibers or glass fibers.

Examples of antistatic agents are bis (2-hydroxyethyl) cocosamine, fatty acid ester or aliphatic sulfonates.

Examples of dyes and / or pigments are chromium oxide, iron oxide, titanium dioxide, ultramarine blue or soot.

Examples of other impact modifiers are polyurethanes with elastomeric properties or other elastomers, like the ones listed above Links.

Examples of electrical conductivity mediating additives are soot or Metal particles, such as aluminum or copper powder, as well as steel fibers, Carbon fiber or graphite.

Examples of other polymeric lubricants are ultra high molecular weight polyethylene (PE-UHMW), polytetrafluoroethylene (PTFE) or aramid powder or fiber.

The manufacture and processing of the compositions according to the invention can by mixing the finely divided, for example powdered or granulated components and subsequent thermoplastic processing done or by mixing the components in suitable heatable mixing units. Suitable mixing units and processes are described for example in: Saechtling, Kunststoff-Taschenbuch, Hanser Verlag, 27th edition 1998, on pages 202 to 217, to which reference is taken.

The mixture of the components of the compositions according to the invention can be carried out, for example, in kneaders, for example in Brabender kneaders.

Is preferably used as a mixing unit a screw machine used, in particular an extruder, such as a twin screw extruder. Processing is preferably done in the injection molding process.

The advantageous processing temperatures are usually in the range from 180 to 230 ° C, advantageous between 190 to 210 ° C.

The compositions of the invention leave for All types of molded parts, including foils and profiles, use with high tribological requirements, for example for leadership and sliding bushes, gears, Gearboxes, transport chains, cam and cam disks, zippers, switches, Roller and slide guides, Rotary traps for _ Car locks, Wiper bearings or guides for car window lifters.

The invention therefore also relates to the use of the compositions for the abovementioned Purposes.

The following examples explain the Invention without limiting it. Quantities are given here unless otherwise stated, always in parts by weight.

For the examples, a copolymer of trioxane and dioxolane with a melt volume index MVI 190/2 was used by 16 8 cm ^3/10 min. The components listed in the table below were added to the copolymer. The amounts used were given as parts by weight.

Table 1

The POM copolymer with the respective additives was in a high-speed fluid mixer, Diosna V100 (Dierk u. sons, Osnabrück, Federal Republic of Germany) and a twin screw extruder Megacompounder ZSK 25 WLE, Fa. Werner u. Pfleiderer, Stuttgart at a melt temperature of 200 ° C melted and then granulated. The granules were dried at 120 ° C for eight hours and subsequently to test specimens for mechanical and tribological tests injected. As an injection molding machine the type KM 90/210 B (from Krauss Maffei, Munich, Federal Republic of Germany) was used. The Processing conditions were based on the recommendations of ISO 9988-2, Fabric standard for POM.

measurements

Rheological properties: MVR 190/2, 16 according to ISO 1133
Mechanical properties: tensile test according to ISO 527 part 1 and 2 impact strength according to ISO 179/1 eU

Wear measurements:

The abrasion was measured on a wear shaft, a rotating shaft on the cylindrical specimen with 12 mm diameter from the test item Were pressed.

The wear volume became dependent determined by time. The test principle corresponded to ISO / DIS 7148-2 the "pin on ring "principle.

test conditions

material Wave: steel Shaft diameter: 65 mm roughness March: 0.8 μm Burden: 3.1 N Sliding speed: 136 m / min Duration of test: 60 hours

The measurement results are as follows Table 2 listed.

Table 2

Claims (12)

Compositions comprising a) at least one polyoxymethylene homo- or copolymer, b) at least one graft copolymer which has an olefin polymer as the graft base and grafted thereon at least one vinyl polymer or an ether polymer, and / or a graft copolymer which has a rubber-elastic core based on polydiene and a hard graft shell made of (meth) acrylate and / or (Meth) acrylonitrile or from styrene and at least one (meth) acrylate and / or (meth) acrylonitrile, and c) at least one lubricant selected from the group consisting of silicone oils with a molecular weight (weight average) of at least 20,000, of alpha-olefins derived oils, from polyolefin waxes, from alkyl esters of carboxylic acids with ten to one hundred carbon atoms or from combinations of these lubricants. Compositions according to claim 1, characterized in that Component b) is a graft copolymer which is an ethylene polymer Has graft base and grafted onto it styrene-acrylonitrile or styrene-methacrylate. Compositions according to claim 2, characterized in that Component c) is an oil derived from alpha olefins. Compositions according to claim 2, characterized in that Component c) a combination of a polyolefin wax with a Alkyl ester of a carboxylic acid with ten to one hundred carbon atoms. Compositions according to claim 2, characterized in that Component c) a combination of alpha-olefins derived oil with a Polyolefin wax and an alkyl ester of a carboxylic acid is ten to one hundred carbon atoms. Compositions according to claim 1, characterized in that Component b) is a graft copolymer that has a rubber elastic Core based on polybutadiene and / or polyisoprene and / or polybutadiene / styrene and a hard graft shell from styrene and methacrylate. Compositions according to claim 6, characterized in that Component c) a silicone oil With a weight average molecular weight of at least 20,000 is. Compositions according to claim 6, characterized in that Component c) is an oil derived from alpha-olefins. Compositions according to claim 6, characterized in that Component c) a combination of a polyolefin wax with a Alkyl ester of a carboxylic acid with ten to one hundred carbon atoms. Compositions according to claim 6, characterized in that Component c) a combination of an oil derived from alpha-olefins with a Polyolefin wax and an alkyl ester of a carboxylic acid is ten to one hundred carbon atoms. Use of the compositions according to claim 1 for manufacture of molded parts. Use according to claim 11, characterized in that it the molded parts are about and sliding bushes, gears, Gearboxes, transport chains, cam and cam disks, zippers, switches, Roller and slide guides, Rotary traps for Car locks, Wiper bearings and guides for car window lifters is.