WO2000026299A1

WO2000026299A1 - Polyoxymethylene molding materials with improved thermostability, nucleation tendency and discoloration resistance

Info

Publication number: WO2000026299A1
Application number: PCT/EP1999/007955
Authority: WO
Inventors: Dieter Ruchatz; Klaus Dorn
Original assignee: Basf Aktiengesellschaft
Priority date: 1998-10-30
Filing date: 1999-10-20
Publication date: 2000-05-11

Abstract

The invention relates to polyoxymethylene molding materials which contain (i) at least one polyoxymethylene homo- and/or copolymer, (ii) at least one conventional adjuvant and (iii) at least one polymeric plastic material as additive which at the same time promotes nucleation and improves thermostability. Said molding materials are characterized in that (iii) is a copolymer which is obtained by polymerization in substance or in solution of a mixture of A1) 0.1-100 parts of one or more cross-linking agents with at least two polymerizable carbon-carbon double bonds, A2) 0.1-99.9 parts of one or more acrylates and/or methacrylates, B) 0.1-99.9 parts of one or more acrylamides and/or methacrylamides and/or dialkylaminoalkylacrylates and/or dialkylaminoalkylmethacrylates, C) based on 100 parts A) + B) > 0.2 to 10 parts molecular weight controller and D) based on 100 parts A) + B) up to 5 parts radicalic polymerization initiators. The molding materials are further characterized in that (iii) is contained in the molding material in an amount of 0.01 to 2 parts based on the sum of (i) + (ii), whereby all amounts relate to parts by weight (wt/wt) and A1), A2) and B) together must give 100 parts. The use of cross-linked polymers in POM molding materials results in advantages with respect to the thermal stability, resistance to discoloration and at the same time to the nucleation tendency of POM molded materials.

Description

Polyoxymethylene molding compounds with improved

Thermostability, tendency to nucleation and

Discoloration stability

The invention relates to nucleated polyoxymethylene molding compositions which can be reinforced or unreinforced, with improved discoloration stability, and moldings therefrom by using certain non-yellowing additives which have a nucleating and stabilizing effect in polyoxymethylene.

In particular, the invention relates to reinforced or unreinforced polyoxymethylene molding compositions

(i) at least one polyoxymethylene homo- and / or copolymer,

(ii) at least one customary additive and (iii) at least one polymeric plastic material.

Polyoxymethylene (POM, polyacetal) is an excellent material from which a wide variety of everyday objects can be produced, particularly by injection molding. The chemical resistance to many organic solvents and bases is particularly advantageous. Since the market launch of polyacetals, various attempts have been made to improve the properties of polyoxymethylene in a targeted manner, so that its technical application spectrum could be broadened further.

Polyoxymethylene homopolymers and / or copolymers are particularly suitable for the production of reinforced or unreinforced molding compositions. In order to improve their processability, mechanical properties and thermal stability, the polyoxymethylene homo- and / or copolymers with conventional additives and at least mixed with an additive to improve the thermal stability and at least one additive for nucleation.

It is known that polyacetals (polyoxymethylenes, POM) as semi-crystalline materials have a pronounced tendency to crystallize. The degree of crystallization depends, among other things, on the comonomer content and is between 50 to 80% (Ullmann's Encyclopedia of Industrial Chemistry, Vol. A21, 1992, VCH Publishers, Inc.). Even with a slight subcooling of a polyoxymethylene melt, rapid growth of spherulites is observed, which are usually larger than the light wavelength and give the material a high opacity. In addition, as a result of the crystallization process, numerous microscopic cracks and internal stresses arise inside and on the surface of the material. Through these cracks and internal stresses, the mechanical properties of moldings, eg. B. injection molded parts, adversely affected by polyoxymethylene. The flaws described are more pronounced the larger the individual spherulites are.

The size and number of spherulites in polyoxymethylene and thus their mechanical properties depend crucially on the type and number of crystallization nuclei. Nucleating agents act as crystallization agents or crystallization accelerators and increase the number of spherulites while simultaneously reducing and standardizing the spherulite size. The resulting spherulite structure of nucleated polyoxymethylenes is much finer and more uniform than that of non-nucleated polyoxymethylenes, which is reflected in significantly improved mechanical properties (H. Domininghaus: The plastics and their properties, 3rd edition, VDI-Verlag, Düsseldorf, 1988, 307 -336; H. Cherdron et al .: Makromol. Chem. Suppl. 1975, 1, 621-636). Spiked with nucleating agents

Polyoxymethylenes also solidify significantly faster and thus enable a shorter cycle time during injection molding. To improve the mechanical properties and cycle time of polyoxymethylenes, it is necessary to reduce and standardize the spherulite size. This is achieved through the use of

Nucleating agents reached. Inorganic and organic materials are proposed as nucleating agents for polyoxymethylenes. These include talc (DE 12 47 645), boron nitride (US 3 767 610), branched or cross-linked polyoxymethylene (DE 21 01 817), trioxane

Block copolymers (DE 21 42 091) or special melamine-formaldehyde polycondensates (DE 25 40 207).

Of the nucleating agents listed above, the latter melamine-formaldehyde polycondensates have by far achieved the greatest commercial importance as nucleating agents in polyoxymethylene due to their excellent nucleating action and are therefore used to a large extent in commercial polyoxymethylenes. Compared to all other known nucleating agents for polyoxymethylene, the melamine-formaldehyde condensates mentioned also show a considerable improvement in the thermal stability of polyoxymethylene. This is another reason for the widespread use of these melamine-formaldehyde condensates as a nucleating and at the same time stabilizing additive in polyoxymethylenes. The advantage of melamine-formaldehyde condensates over inorganic nucleating agents or branched or crosslinked polyoxymethylenes is therefore the combination of nucleating agent and heat stabilizer in a single substance.

Nucleating agents which combine nucleating and stabilizing properties also facilitate the preparation, handling and metering of the additive mixture which is to be added to the polyoxymethylene and is absolutely necessary for stabilization and nucleation and which comprises at least one antioxidant, one nucleating agent and a heat stabilizer; other additives, such as. B. pigments, lubricants, formaldehyde scavengers or light stabilizers can optionally be added to this mixture. The fewer components of this basic stabilizing composition, consisting of an antioxidant, a nucleating agent and a heat stabilizer, the lower the risk of partial or complete segregation of the individual components of this additive mixture during its production, conveyance and metering, as is typically the case with solid mixtures due to density differences , Differences in the grain size distribution and different bulk densities of the individual components contained therein occur. If the described separation of the individual components occurs when the basic stabilization mixture consisting of the components described above is added to the polyoxymethylene melt, the optimal concentration of the individual stabilizers and of the nucleating agent in polyoxymethylene originally intended in polyoxymethylene deviates more or less strongly from the actual concentration in polyoxymethylene with the result that the properties, in particular the stability and the mechanical properties, of the polyoxymethylene are adversely affected.

It is therefore desirable to keep the number of individual components in the additive mixture as low as possible in order to minimize the risk of segregation of the individual components when handling the reaction mixture and thus always to maintain a constant and optimal concentration of the

To achieve stabilizers and nucleating agents in polyoxymethylene. The melamine-formaldehyde condensate already described contributes to reducing the number of individual components, since, as already mentioned, it simultaneously takes on the function of a heat stabilizer and nucleating agent. However, melamine-formaldehyde condensates have the disadvantage of increasing the yellowing of polyoxymethylenes, especially after warm storage. For the vast majority of applications, however, polyoxymethylene that is as free of yellowing as possible is required. Low-yellowing or even non-yellowing additives which, like the melamine-formaldehyde condensates, have a nucleating and, at the same time, a stabilizing effect on polyoxymethylenes, have not been proposed to date. Low-yellowing or yellowing-free nucleating agents exist, but they have no thermostabilizing effect. If exclusively nucleating additives are used in polyoxymethylene, at least one further additive must therefore be added for heat stabilization, with the disadvantage that the above-mentioned segregation can occur during metering.

In view of the state of the art specified and set out herein, it was therefore an object of the invention to provide reinforced or unreinforced polyoxymethylene molding compositions for industrial production which are superior to the POM molding compositions used hitherto in practice. In particular, the new POM molding compositions should have a lower tendency to discolour than previously known POM molding compositions. Finally, it is also aimed at nucleation and heat stabilization with a single

To achieve additive, which should also be easy and inexpensive to manufacture.

These and other tasks, which are not described in more detail, are solved by a polyoxymethylene molding compound of the type specified at the beginning with the features of the characterizing part of claim 1. Advantageous refinements are the subject of the subordinate claims which are referred to claim 1. With regard to the method aspects, the technical teaching given in claim 21 solves the problems of the invention. Appropriate uses are protected in claims 22 and 23. Claims 24 and 25 are directed to moldings and semi-finished products or films produced from the molding compositions according to the invention.

Characterized in that in polyoxymethylene molding compositions

(i) at least one polyoxymethylene homo- and / or copolymer and

(ii) at least one common additive

a copolymer is used as additive (iii) to simultaneously improve the tendency to nucleation and thermostability, which is obtained by polymerization in solution or substance of a mixture of

AI) 0.1-100 parts of one or more crosslinkers with at least two polymerizable carbon-carbon double bonds A2) 0-99.9 parts of one or more acrylates and / or methacrylates

B) 0 to 99.9 parts of one or more acrylamides and / or methacrylamides and / or dialkylaminoalkyl acrylates and / or dialkylaminoalkyl methacrylates

C) based on 100 parts of AI) + A2) + B) 0 to 10 parts of molecular weight regulator and

D) based on 100 parts of AI) + A2) + B) up to 5 parts of free-radical polymerization initiators is available,

and that

(iii) in an amount of 0.01 to 2 parts based on the sum of (i) + (ii) is contained in the molding composition, where all amounts relate to parts by weight (wt / wt) and AI), A2) and B) must total 100 parts, the problems on which the invention is based are solved in an unpredictable manner. In particular, it was found, quite surprisingly, that the polymeric additives (iii) according to the invention, in addition to a heat-stabilizing effect with less tendency to discolouration, also have a nucleating effect in polyoxymethylenes.

Thus, the reinforced or unreinforced molding composition based on polyoxymethylene according to the invention offers POM molding compositions known from the prior art, in particular compared to the compositions known from DE-PS 25 40 207, u. a. the advantage of causing significantly less yellowing in polyoxymethylenes.

Component (i)

Component (i) is an essential component of the molding composition according to the invention. These are polyoxymethylene homopolymers and / or copolymers, in the context of the invention being understood here to mean both a homopolymer alone, several homopolymers in a mixture with one another, a copolymer alone, a plurality of copolymers in a mixture with one another and mixtures which are one or more homopolymers have together with one or more copolymers.

The polyoxymethylenes which form the main constituent (i) of the molding compositions according to the invention can be homopolymers of formaldehyde or trioxane or copolymers of trioxane. They can have a linear structure, but can also be branched or networked. They can be used individually or as a mixture.

Homopolymers of formaldehyde or trioxane are understood to mean those polymers whose semiacetal hydroxyl end groups are chemically stabilized against degradation, for example by esterification or etherification. Among copolymers of trioxane Copolymers of trioxane and at least one compound copolymerizable with trioxane understood.

The homopolymers have i. d. R. thermally stable end groups such as ester or ether groups. The copolymers of formaldehyde or trioxane advantageously have more than 50%, in particular more than 75%, of oxymethylene groups. Copolymers which contain at least 0.1% by weight of groups of the copolymer which have at least two adjacent carbon atoms in the chain have proven particularly useful. Polyoxymethylenes which contain 1 to 10% by weight of comonomers have acquired particular industrial importance.

In the context of the invention, polyoxymethylene copolymers are preferred as component (i) which, in addition to the repeating units -CH2O-, also up to 50, preferably 0.1 to 20 and in particular 0.3 to 10 mol% of repeating units

have, wherein R ^ 'to R ^' independently of one another a hydrogen atom, a C ~ to C4 ~ alkyl group or a halogen-substituted alkyl group having 1 to 4 C atoms and R ⁵ 'a -CH2-, -CH2O-, a C ~ bis C4 ~ alkyl or Cχ ~ to C4-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 the formula

where R 'to R ^' and n have the meaning given above.

Compounds of the formula in particular are suitable as comonomers

CH ₂ - (CHR) _X - [O— (CH ₂ ) _z ] yO (I ')

suitable in which R is a hydrogen atom, an alkyl radical having 1 to 6, preferably 1, 2 or 3 carbon atoms, which can be substituted by 1, 2 or 3 halogen atoms, preferably chlorine atoms, an alkoxymethyl radical having 2 to 6, preferably 2, 3 or 4 carbon atoms, a phenyl radical or a phenoxymethyl radical, x is an integer from 1 to 3, where y is zero, y is an integer from 1 to 3, where x is zero and z is 2, and z is an integer from 3 to 6, preferably 3 or 4, where x is zero and y is 1.

Particularly suitable cyclic ethers are epoxides, e.g. As ethylene oxide, styrene oxide, propylene oxide or epichlorohydrin, and glycidyl ether of mono- or polyhydric alcohols or phenols.

Particularly suitable cyclic acetals are cyclic formals of aliphatic or cycloaliphatic α, ω-diols with 2 to 8, preferably 2, 3 or 4

Carbon atoms whose carbon chain can be interrupted by an oxygen atom at intervals of 2 carbon atoms, e.g. B.:

Glycol formal (1,3-dioxolane), propanediol formal (1,3-dioxane)

Butanediol formal (1,3-dioxepane) and

Diglycol formal (1, 3, 6-trioxocane) as well

4-chloromethyl-l, 3-dioxolane,

Hexanediol formal (1,3-dioxonane) and butenediol formal (1,3-dioxacyclohepten-5). Suitable linear polyacetals are both homopolymers or copolymers of the cyclic acetals defined above and linear condensates of aliphatic or cycloaliphatic α, ω-diols with aliphatic aldehydes or thioaldehydes, preferably formaldehyde. In particular, homopolymers of cyclic formals of aliphatic α, ω-diols with 2 to 8, preferably 2, 3 or 4 carbon atoms are used, for. B. poly- (1,3-dioxolane), poly- (1,3-dioxane) and poly- (1,3-dioxepane).

The values for the viscosity number of the polyoxymethylenes used according to the invention (measured on a solution of the polymer in hexafluoroisopropanol, which is adjusted to pH 8 to 9 with methanolic sodium hydroxide solution, at 25 ° C. in a concentration of 0.3 g / 100 ml) should generally be at least 160 (ml / g). The crystallite melting points of the polyoxymethylenes are in the range from 140 to 180.degree. C., preferably 150 to 170.degree. C., their densities are 1.38 to 1.45 gx ml ^~ l, preferably 1.40 to 1.43 gx ml ^~ l (measured according to DIN 53 479). As a rule, the polyoxymethylenes used have a number average

Molecular weight M _n from 2,000 to 200,000, preferably from 10,000 to 100,000, and a volume flow index (melt volume rate, MVR) at 190 ° C and a contact force of 2.16 kg according to DIN ISO 1133 of 0.5 to 200 ^3/10 min cm, preferably from 1 to 70 cm ^3/10 min.

The preferably binary or ternary trioxane copolymers used according to the invention are prepared in a known manner by polymerizing the monomers in the presence of cationically active catalysts at temperatures between 0 and 150 ° C, preferably between 70 and 140 ° C (cf. e.g. DE -AS 14 20 283). Examples of catalysts used here are Lewis acids, such as boron trifluoride or antimony pentafluoride, and complex compounds of such Lewis acids, preferably etherates, for. B. boron trifluoride diethyl etherate or boron trifluoride di-tert. -butyl etherate used. Protonic acids, e.g. B. Perchloric acid, as well as salt-like compounds, e.g. B. triphenylmethylhexafluorophosphate or

Triethyloxonium tetrafluoroborate, acetyl perchlorate or esters of perchloric acid, e.g. B. methoxymethyl perchlorate or tert. Butyl perchlorate. All substances which are known to act as chain transfer agents in the polymerization of trioxane can be used to regulate the molecular weight. The polymerization can be carried out continuously or batchwise in bulk, suspension or solution by the processes known for trioxane homo- and copolymerization. To remove unstable fractions, the copolymers can be subjected to a thermal or hydrolytically controlled, partial degradation down to primary alcohol end groups (see, for example, DE-AS 14 45 273 and 14 45 294).

The homopolymers of formaldehyde or trioxane used according to the invention are also prepared in a known manner by catalytically polymerizing the monomer (cf., for example, DE-AS 10 37 705 and 11 37 215).

Polymers which are composed of trioxane and 1 to 10% by weight of ethylene oxide, 1,3-dioxolane or butanediol formal have become particularly important. As additional comonomers for trioxane, compounds with several polymerizable groups in the molecule, for. B. alkyl glycidyl formal, polyglycol diglycidyl ether, alkanediol diglycidyl ether, e.g. B.

1, 4-butanediol diglycidyl ether or bis (alkanetriol) - triformale can be used. But are also suitable, in particular for the production of terpolymers of trioxane, diformals, for. B. Diglycerol diformal.

They are usually used in an amount of 0.05 to

5 wt .-%, preferably 0.1 to 2 wt .-%, based on the

Total amount of monomer applied. Component (i) is present in the molding composition according to the invention in an amount of 40 to 99.99, advantageously 70 to 99.99 and in particular 95 to 99.9% by weight, based on the weight of component (i), (ii) and (iii). The molding composition according to the invention particularly advantageously consists of components (i), (ii) and (iii).

Component (ii)

Another essential component of the reinforced or unreinforced polyoxymethylene molding composition according to the invention is component (ii). This is an additive, but several additives can also be used at the same time.

Depending on how the advantageous property profile of the molding composition according to the invention is to be varied further, one or more additives (ii) are used.

The additives (ii) can come from a wide variety of compound classes and can produce a wide variety of technical effects. All additives which are usually intended for use in reinforced or unreinforced polyoxymethylene molding compositions are suitable as additives (ii).

Examples of suitable additives (ii) are costabilizers, reinforcing fillers such as inorganic fibers such. B. carbon fibers or glass fibers, organic polymer fibers such. B. aramid fibers (Nomex ^® , Kevlar ^® ) or polyacrylonitrile fibers, wollastonites and chalk, talc, carbon black and potassium titanates, nucleating agents, antistatic agents, light and flame retardants, lubricants and lubricants, plasticizers, antioxidants, pigments, dyes, optical brighteners, internal release agents , Impact modifiers such as polyurethane rubbers or graft rubbers based on polymerized (meth) acrylic acid esters, polymerized (Meth) acrylonitrile and / or polymerized butadiene and polymers such as polyalkylene terephthalates.

Thermoplastic polyurethanes (TPU) enjoy particular preference among the additives (ii).

Suitable TPUs can be produced, for example, by reacting

a) organic, preferably aromatic diisocyanates,

b) polyhydroxyl compounds with molecular weights of 500 to 8000 and

c) chain extenders with molecular weights of 60 to 400 in the presence of optionally

d) catalysts,

e) auxiliaries and / or additives.

The following applies to the starting materials (a) to (c), catalysts (d), auxiliaries and additives (e) which can be used for this:

a) Suitable organic diisocyanates (a) are, for example, aliphatic, cycloaliphatic and preferably aromatic diisocyanates. Examples include: aliphatic diisocyanates such as hexamethylene diisocyanate, cycloaliphatic diisocyanates such as isophorone diisocyanate, 1,4-cyclohexane diisocyanate, 1-methyl-2, - and -2, 6-cyclohexane diisocyanate and the corresponding isomer mixtures , 4,4'-, 2,4'- and

2,2'-dicyclohexylmethane diisocyanate and the corresponding isomer mixtures and preferably aromatic diisocyanates, such as 2,4-tolylene diisocyanate, mixtures of 2,4- and 2,6-tolylene diisocyanate, 4,4'-, 2,4 '- and 2, 2'-diphenylmethane diisocyanate. Mixtures of 2,4'- and 4,4'-diphenylmethane diisocyanate, urethane-modified liquid 4,4'- and / or 2,4'-diphenylmethane diisocyanates, 4,4'-diisocyanatodiphenylethane (1,2) and 1,5-naphthylene diisocyanate. Hexamethylene diisocyanate, isophorone diisocyanate, 1,5-naphthylene diisocyanate,

Diphenylmethane diisocyanate isomer mixtures with a, 4'-diphenylmethane diisocyanate content of greater than 96% by weight and in particular 4,4'-diphenylmethane diisocyanate.

Polyetherols and polyesterols are preferably suitable as higher molecular weight polyhydroxyl compounds (b) with molecular weights of 500 to 8000. However, hydroxyl-containing polymers, for example polyacetals, such as polyoxymethylenes and, above all, water-insoluble formals, for example. B.

Polybutanediol formal and polyhexanediol formal, and polycarbonates, especially those made from diphenyl carbonate and hexanediol-1, 6, produced by transesterification, with the above-mentioned molecular weights. The polyhydroxyl compounds must be at least predominantly linear, i.e. H. be constructed difunctionally in the sense of the isocyanate reaction. The polyhydroxyl compounds mentioned can be used as individual components or in the form of mixtures.

Suitable polyetherols can be prepared by reacting one or more alkylene oxides with 2 to 4 carbon atoms in the alkylene radical with a starter molecule which contains two active hydrogen atoms bonded. As alkylene oxides such. B. called: ethylene oxide, 1, 2-propylene oxide, 1,2- and 2,3-butylene oxide. Ethylene oxide and mixtures of propylene oxide-1, 2 and ethylene oxide are preferably used. The alkylene oxides can be used individually, alternately in succession or as a mixture. Examples of suitable starter molecules are: water, amino alcohols, such as N-alkyl diethanolamines, for example N-methyl-diethanolamine and diols, such as ethylene glycol, 1,3-propylene glycol, 1,4-butanediol and 1, 6-hexanediol. mixtures of starter molecules can also be used. Suitable polyetherols are also the hydroxyl-containing polymerization products of tetrahydrofuran (polyoxytetramethylene glycols).

Polyetherols of propylene oxide-1, 2 and ethylene oxide are preferably used in which more than 50%, preferably 60 to 80% of the OH groups are primary hydroxyl groups and in which at least part of the ethylene oxide is arranged as a terminal block; z. B. in particular polyoxytetramethylene glycols.

Such polyetherols can be obtained by e.g. B. to the starter molecule first

Polymerized propylene oxide-1, 2 and then the ethylene oxide or first copolymerized all of the propylene oxide-1, 2 in a mixture with part of the ethylene oxide and then polymerized the rest of the ethylene oxide or gradually a part of the ethylene oxide, then the entire propylene oxide-1, 2 and then the rest of the ethylene oxide, polymerized onto the starter molecule.

The essentially linear polyetherols have molecular weights of 500 to 8000, preferably 600 to 6000 and in particular 800 to 3500. They can be used both individually and in the form of mixtures with one another.

Suitable polyesterols can be prepared, for example, from dicarboxylic acids having 2 to 30 carbon atoms, preferably 4 to 8 carbon atoms and polyhydric alcohols. Examples of suitable dicarboxylic acids are: aliphatic dicarboxylic acids, such as succinic acid, glutaric acid, Adipic acid, suberic acid, azelaic acid and sebacic acid and aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid. The dicarboxylic acids can be used individually or as mixtures, e.g. B. in the form of a succinic, glutaric and adipic acid mixture. Mixtures of aromatic and aliphatic dicarboxylic acids can also be used. To prepare the polyesterols, it may be advantageous to use the corresponding dicarboxylic acid derivatives, such as dicarboxylic acid esters with 1 to 4 carbon atoms in the alcohol radical, instead of the dicarboxylic acids,

To use dicarboxylic acid anhydrides or dicarboxylic acid chlorides. Examples of polyhydric alcohols are glycols with 2 to 10, preferably 2 to 6, carbon atoms, such as ethylene glycol, diethylene glycol, 1,4-butanediol, 1, 5-pentanediol, 1, 6, hexanediol, 1, 10, 2, 2-decanediol Dimethylpropanediol-1, 3, propanediol-1, 3 and dipropylene glycol. Depending on the desired properties, the polyhydric alcohols can be used alone or, if necessary, in mixtures with one another.

Also suitable are esters of carbonic acid with the diols mentioned, in particular those with 4 to 6 carbon atoms, such as 1,4-butanediol and / or 1,6-hexanediol, condensation products of ω-hydroxycaproic acid and preferably polymerization products of lactones, for example optionally substituted ω -Caprolactones.

Dialkylene glycol polyadipates containing 2 to 6 are preferably used as polyesterols

Carbon atoms in the alkylene radical, such as. B. ethanediol polyadipates, 1,4-butanediol polyadipates, ethanediol-butanediol-1,4-polyadipates, 1,6-hexanediol-neopentylglycol polyadipates, polycaprolactones and in particular 1,6-hexanediol-1,4-butanediol polyadipates . The polyesterols have molecular weights from 500 to 6000, preferably from 800 to 3500.

As chain extender (c) with

Molecular weights of 60 to 400, preferably 60 to 300, come preferably aliphatic diols having 2 to 30 carbon atoms, preferably 2, 4 or 6 carbon atoms, such as. B. ethanediol, hexanediol-1, 6, diethylene glycol, dipropylene glycol and in particular butanediol-1. However, diesters of terephthalic acid with glycols having 2 to 4 carbon atoms, such as. B. terephthalic acid bis-ethylene glycol or -butandιol-1, 4, hydroxyalkylene ether of the hydrochmon, such as. B. 1, 4-Dι- (ß-hydroxyethyl) - hydroquinone, (cyclo) aliphatic diamines, such as. B. 4, 4'-Dιamιno-dιcyclohexylmethane, 3, 3'-Dιmethyl-4, 4'-diammodicyclohexylmethane, isophorone-diamm, ethylenediamine, 1,2- 1,3-propylene-dιamm, N-methyl-propylene -dιamm-1, 3, N, N'-dimethyl-ethylenediamine and aromatic diamines, such as. B. 2,4- and 2, 6-tolylene diamm, 3, 5-dimethyl-2, 4- and -2, 6-toluylene diamm and primary ortho-di-, tri- and / or tetraalkyl-substituted 4, 4th '-Dιamιno-dιphenylmethane.

To set the hardness and melting point of the TPU, the structural components (b) and (c) can be varied in relatively wide molar ratios. Molar ratios of

Polyhydroxyl compounds (b)

Chain extenders (c) from 1: 1 to 1:12, in particular from 1: 1.8 to 1: 6.4, the hardness and melting point of the TPU increasing with the content

Diols increases.

To produce the TPU, the structural components (a), (b) and (c) are reacted in the presence of any catalysts (d), auxiliaries and / or additives (e) in amounts such that the Equivalence ratio of NCO groups of the diisocyanates (a) to the sum of the hydroxyl groups or hydroxyl and amino groups of components (b) and (c) 1: 0.85 to 1.20, preferably 1: 0.95 to 1: 1.05 and in particular 1: 0.98 to 1.02.

d) Suitable catalysts, which in particular the

Accelerate reaction between the NCO groups of the diisocyanates (a) and the hydroxyl groups of the structural components (b) and (c) are the conventional tertiary amines known and known in the art, such as. B. triethylamine, dirnethylcyclohexylamine,

N-methylmorpholine, N, N'-dimethylpiperazine, 2- (dimethylaminoethoxy) ethanol, diazabicyclo- (2, 2, 2) octane and similar and in particular organic metal compounds such as titanium acid esters,

Iron compounds such as B. iron (III) acetylacetonate, tin compounds, z. B. tin diacetate, tin dioctoate, tin dilaurate or the tin dialkyl salts of aliphatic carboxylic acids such as dibutyltin diacetate, dibutyltin dilaurate or the like. The catalysts are usually used in amounts of 0.001 to 0.1 part per 100 parts of polyhydroxyl compound (b).

In addition to catalysts, auxiliary components and / or additives (e) can also be incorporated into the structural components (a) to (c). Lubricants may be mentioned, for example

Inhibitors, stabilizers against hydrolysis, light, heat or discoloration and plasticizers.

Further information on the above-mentioned auxiliaries and additives can be found in the specialist literature, for example the monograph by JH Saunders and KC Frisch "High Polymers", Volume XVI, Polyurethane, Parts 1 and 2, Verlag Interscience Publishers 1962 and 1964 or DE-OS 29 01 774. Preferred components (ii) in the molding composition according to the invention are also elastomers which

Emulsion polymerization were prepared and z. B. are described in Blackley in the monograph "Emulsion Polymerization". The emulsifiers and

Catalysts are known per se. In principle, homogeneously constructed elastomers or those with a shell structure can be used, so-called core-shell polymers. The shell-like structure is determined by the order of addition of the individual monomers .; the morphology of the polymers is also affected by this order of addition.

Only representative here are monomers for the production of the rubber part of the elastomers, such as acrylates. B. n-butyl acrylate and 2-ethylhexyl acrylate, corresponding methacrylates, butadiene and isoprene and mixtures thereof. These monomers can with other monomers such as. B. styrene, acrylonitrile, vinyl ethers and other acrylates or methacrylates such as methyl methacrylate, methyl acrylate, ethyl acrylate and propyl acrylate are copolymerized.

The soft or rubber phase (with a glass transition temperature below 0 ° C) of the elastomers can be the core, the outer shell or a middle shell (in the case of elastomers with more than two shells); in the case of multi-layer elastomers, several shells can also consist of a rubber phase.

If, in addition to the rubber phase, one or more hard components (with glass transition temperatures of more than 20 ° C) are involved in the construction of the elastomer, these are generally made by polymerizing styrene, acrylonitrile, methacrylonitrile, α-methylstyrene, p-methylstyrene, acrylic acid esters and methacrylic acid esters such as methyl acrylate, ethyl acrylate and methyl methacrylate as main monomers. Besides that, here too lower proportions of other comonomers are used.

In some cases it has proven to be advantageous to use emulsion polymers which have reactive groups on the surface. such

Groups are e.g. B. epoxy, amino or amide groups and functional groups by the use of monomers of the general formula

can be introduced, where the substituents can have the following meanings:

R ^{1 "is} hydrogen or a C ¹ -C ₄ alkyl group

R ² "is hydrogen, a Ci to Cg alkyl group or

Aryl group, in particular phenyl R ^{3 "} hydrogen, a Ci to Cι ₀ alkyl, a C ₆ - to Cι ₂ -

Aryl group or -OR ^{4 "} R ^{4" is} a Ci- to C ₈ -alkyl or C ₆ - to -CC ₂ aryl group, which can optionally be substituted with 0 or N-containing groups, X is a chemical bond, a Ci to Cι ₀ -alkylene or

C ₆ - to Cι ₂ arylene group or

Y O-Z or NH-Z and

Z is a Cι ~ to Cι ₀ alkylene or C ₆ - to Cχ ₂ arylene group.

The graft monomers described in EP-A 208 187 are also suitable for introducing reactive groups on the surface. Further examples include acrylamide, methacrylamide and substituted esters of acrylic acid or methacrylic acid such as (Nt-butylamino) ethyl methacrylate,

(N, N-dimethylamino) ethyl acrylate, (N, N-dimethylamino) methyl methacrylate and

(N, N-Diethylamino) called ethyl acrylate.

The particles of the rubber phase can also be crosslinked. Monomers acting as crosslinking agents are, for example, buta-1, 3-diene, divinylbenzene, diallyl phthalate and dihydrodicyclopentadienyl acrylate and the compounds described in EP-A 50 265.

Furthermore, so-called graft-linking monomers can also be used, i.e. H. Monomers with two or more polymerizable double bonds, which react at different rates during the polymerization. Those compounds are preferably used in which at least one reactive group polymerizes at approximately the same rate as the other monomers, while the other reactive group (or reactive groups) z. B. polymerized significantly slower (polymerize). The different polymerization rates result in a certain proportion of unsaturated double bonds in the rubber. If a further phase is subsequently grafted onto such a rubber, the double bonds present in the rubber react at least partially with the graft monomer to form chemical bonds, ie. H. the grafted phase is at least partially linked to the graft base via chemical bonds.

Examples of such graft-crosslinking monomers are monomers containing allyl groups, in particular allyl esters of ethylenically unsaturated carboxylic acids such as allyl acrylate, allyl methacrylate, diallyl maleate, diallyl fumarate, diallylitavonate or the corresponding Monoallyl compounds of these dicarboxylic acids. There are also a large number of other graft-crosslinking monomers; for further details, reference is made here, for example, to US Pat. No. 4,148,846. In general, the proportion of these crosslinking monomers is up to 5% by weight, preferably not more than 3% by weight, based on the elastomer or emulsion polymer.

Some preferred emulsion polymers are listed below. First of all, there are graft copolymers with a core and at least one outer shell that have the following structure:

Monomers for the core Monomers for the shell

Buta-1,3-diene, isoprene, styrene, acrylonitrile, n-butyl acrylate, acrylates, methacrylates, optionally ethylhexyl acrylate or those with reactive groups such as mixtures, optionally together with monomers crosslinking described herein

Instead of graft polymers with a multi-layer structure, homogeneous, ie. H. single-shell elastomers of buta-1, 3-diene, isoprene and n-butyl acrylate or their copolymers are used. These products can also be prepared by using crosslinking monomers or monomers with reactive groups. The elastomers described can also by other conventional methods, for. B. by suspension polymerization.

Preferred components (ii) in the molding composition according to the invention are also the so-called ethylene-propylene (EPM) or ethylene-propylene-diene (EPDM) rubbers.

EPM rubbers generally have practically none

Double bonds more, while EPDM rubbers can have 1 to 20 double bonds / 100 carbon atoms. Examples of diene monomers for EPDM rubbers are conjugated dienes such as isoprene and butadiene, non-conjugated dienes having 5 to 25 carbon atoms such as penta-1,4-diene, hexa-1,4-diene, hexa-1,5 -diene, 2, 5-dimethylhexa-l, 5-diene and octa-1, -diene, cyclic dienes such as cyclopentadiene,

Cyclohexadienes, cyclooctadienes and dicyclopentadiene and alkenylnorbornenes such as 5-ethylidene-2-norbornene, 5-butylidene-2-norbornene, 2-methallyl-5-norbornene, 2-isopropenyl-5-norbornene and tricyclodienes such as 3-methyl-tricyclo (5.2. , 1.0.2.6) -3, 8-decadiene or mixtures thereof. Hexa-1,5-diene-5-ethylidene-norbornene and dicyclopentadiene are preferred. The diene content of the EPDM rubbers is preferably 0.5 to 50, in particular 1 to 8,% by weight, based on the total weight of the rubber.

The EPDM rubbers can also be grafted with other monomers, e.g. with glycidyl (meth) acrylates, (meth) acrylic acid esters and (meth) acrylamides.

Further preferred components (ii) in the molding composition according to the invention are suitable compounds, plasticizers, lubricants, antioxidants, adhesion promoters, light stabilizers and pigments for trapping formaldehyde (formaldehyde scavenger).

Lubricants and lubricants that can be added individually or as a mixture can belong to a wide variety of substance classes, such as. B. metal stearates (such as calcium stearate), waxes, fatty acid amides (such as stearic acid amide, bis-stearoyl-ethylenediamide), hydroxycarboxylic acid amides, fatty acids, fatty acid esters, montanic acid esters, paraffin waxes, synthetic paraffins, low molecular weight or oligomeric polyolefin waxes (such as. G. Polyethylene waxes), graft-modified polyolefin waxes, alcohols (such as palmityl alcohol, stearyl alcohol, tallow fatty alcohol), ketones (such as stearone), silicones (such as polydimethylsiloxane), silicone oils , Polysiloxanes, acrylic-modified polysiloxanes, Polytetrafluoroethylene (PTFE), polyalkylene glycols, special fatty acid esters as described in DE 4117655.

Esters of polyhydric alcohols (such as, for example, ethylene glycol, diethylene glycol, butanediol, glycerol, diglycerol, pentaerythritol, sorbitol) with long-chain fatty acids (for example stearic acid, behenic acid, palmitic acid, capric acid, lauric acid, linoleic acid, erucic acid) are particularly preferred, that can be used individually or as a mixture. The hydroxyl groups of the alcohol component in the carboxylic acid ester can either be completely esterified or only partially esterified. Glycerol esters based on saturated fatty acids in which not all hydroxyl groups are esterified are particularly preferred.

Further information on the above-mentioned lubricants and lubricants can be found in Ullmann's encyclopedia

Technical Chemistry, Volume 15, Verlag Chemie, 4th edition (1978) 268-270, Additives for Plastics Handbook, J. Murphy, Elsevier Advanced Technology (1996) 239-255 or Polymeric Materials, Volume 2, H. Batzer, Thieme- Verlag (1984) 328-337.

In principle, all substances which the person skilled in the art can consider for this purpose can serve as light stabilizers. They can be used individually or as a mixture. Light stabilizers based on benzotriazole derivatives (such as 2- (2 '-hydroxy-3', 5 '-di (1, 1-dimethylbenzyl) phenyl) benzotriazole), benzophenone derivatives (such as e.g. 2-hydroxy-4-methoxybenzophenone or 2,2'-dihydroxy-4,4'-dimethoxybenzophenone), aromatic benzoate derivatives (such as, for example, p-octylphenyl salicylate), phenyltriazines,

Cyanocinnamic acid amides or cyanocinnamic acid esters (as described, for example, in WO 9713749), or sterically hindered amine compounds (HALS), for example derivatives of 2, 2, 6, 6-tetramethylpiperidine (such as, for example, a dimethyl succinate polymer with 4-hydroxy-2, 2, 6, 6-tetramethyl 1-piperidineethanol). Benzotriazole derivatives, which are commercially available under the name Tinuvin ^® (registered trademark of Ciba-Geigy AG), have proven to be particularly suitable. Tinuvin ^® 234 is especially preferred: 2- (2 '-hydroxy-3', 5 '-di (1, 1- dimethylbenzyl) phenyl) benzotriazole. Particularly suitable derivatives of 2, 2, 6, 6-tetramethylpiperidine, under the name Tinuvin ^® or Chimasorb® ^® (registered trademark of Ciba-Geigy AG) are commercially available are. Tinuvin are particularly preferred

622 LD from Ciba-Geigy AG: dimethyl succinate polymer with 4-hydroxy-2, 2,6, 6-tetramethyl-l-piperidineethanol, and Tinuvin ^® 770 LD by Ciba-Geigy AG: bis (2, 2,6,6- tetramethyl-4-piperidyl) sebazate.

More details on suitable light stabilizers can be found in the monograph by J. F. Rabek, Photostabilization of Polymers; Principles and Applications, Elsevier Applied Science, NY, 1990.

Polyamides which can also be used as additives are known per se. Semicrystalline or amorphous resins such as z. B. in Encyclopedia of Polymer Science and Engineering, Vol. 11, pp. 315 to 489, John Wiley & Sons, Inc. 1988 can be used, the melting point of the polyamide preferably below 225 ° C, preferably below 215 ° C.

Examples include polyhexamethylene azelaic acid amine, polyhexamethylene sebacic acid amide, polyhexamethylene dodecanedioic acid amide, poly-11-aminoundecanoic acid amide and bis (p-aminocyclohexyl) methane dodecanoic acid diamide or those obtained by ring opening of lactams, e.g. B. or polylaurine lactam products obtained. Also polyamides based on terephthalic or isophthalic acid as the acid component and / or trimethylhexamethylene diamine or bis (p-aminocyclohexyl) propane as the diamine component and polyamide base resins which are obtained by copolymerization of two or several of the aforementioned polymers or their components have been prepared are suitable.

Mixed polyamides based on caprolactam, hexamethylenediamine, p, p'-diamino-dicyclohexylmethane and adipic acid may be mentioned as particularly suitable polyamides. An example of this is the product sold by BASF Aktiengesellschaft under the name Ultramid® 1 C.

Other suitable polyamides are marketed by Du Pont under the name Elvamide®.

The preparation of these polyamides is also described in the aforementioned document. The ratio of terminal amino groups to terminal acid groups can be controlled by varying the molar ratio of the starting compounds.

The proportion of the polyamide in the molding composition according to the invention is preferably 0.005 to 1.99% by weight, in particular 0.01 to 1.5% by weight.

By using a polycondensation product of 2,2-di- (4-hydroxyphenyl) propane (bisphenol A) and

Epichlorohydrin can in some cases improve the dispersibility of the polyamides used.

Such condensation products of epichlorohydrin and bisphenol A are commercially available. Methods for their preparation are also known to the person skilled in the art.

Trade names of the polycondensates are Phenoxy® (from Union Carbide Corporation) and Epikote® (from Shell). The molecular weight of the polycondensates can vary within wide limits; in principle, the types available on the market are all suitable.

The inventive polyoxymethylene molding compositions can contain up to 2.0 as additives (ii) % By weight, preferably 0.005 to 0.5% by weight and in particular 0.01 to 0.3% by weight, based on the total weight of the molding compositions of one or more alkaline earth metal silicates and / or alkaline earth metal glycerophosphates. Calcium and in particular magnesium have proven to be excellent as alkaline earth metals for the formation of the silicates and glycerophosphates. Calcium glycerophosphate and preferably magnesium glycerophosphate and / or calcium silicate and preferably magnesium silicate are expediently used, alkaline earth silicates, in particular those which are preferred by the formula, being particularly preferred

MeO • x SiO2 • n H2O

are described in the mean

Me an alkaline earth metal, preferably calcium or especially magnesium,

x is a number from 1.4 to 10, preferably 1.4 to 6 and

n is a number equal to or greater than 0, preferably 0 to 8.

The compounds are advantageously used in finely ground form. Products with an average particle size of less than 100 μm, preferably less than 50 μm, are particularly suitable.

Calcium and magnesium silicates and / or calcium and

Magnesium glycerophosphates. These can be specified, for example, using the following key data:

Calcium or magnesium silicate: content of CaO or MgO: 4 to 32% by weight, preferably 8 to 30% by weight and in particular 12 to 25% by weight, ratio of SiO ₂ : CaO or SiO ₂ : MgO (mol / mol): 1.4 to 10, preferably 1.4 to 6 and in particular 1.5 to 4, bulk density: 10 to 80 g / 100 ml, preferably 10 to 40 g / 100 ml and average parameter: less than 100 μm, preferably less than 50 μm and

Calcium or magnesium glycerophosphates: CaO or MgO content: greater than 70% by weight, preferably greater than 80% by weight, residue on ignition: 45 to 65% by weight melting point: greater than 300 ° C. and average grain size: smaller than 100 μm, preferably less than 50 μm.

Ambosol ^® , a synthetic magnesium silicate from Societe Nobel, Bozel, Puteaux, has proven to be particularly suitable.

The molding compositions according to the invention can also contain amounts of a fibrous or particulate filler or mixtures thereof as an additive.

As reinforcing fillers, for example, inorganic fibers such as potassium titanate whiskers, carbon and preferably glass fibers may be mentioned, the glass fibers e.g. B. in the form of glass fabrics, mats, nonwovens and / or glass silk rovings or cut glass silk made of low-alkali E-glass with a diameter of 5 to 200 microns, preferably 8 to 50 microns can be used, the fibrous fillers preferably after their incorporation have an average length of 0.05 to 1 mm, in particular 0.1 to 0.5 mm.

Other suitable reinforcing fillers are e.g. B. organic polymer fibers such. B. aramid fibers (Nomex ^® , Kevlar ^® ) or polyacrylonitrile fibers.

Other suitable additional fillers are, for example, wollastonite, calcium carbonate, glass balls, quartz powder, silicon and boron nitride or mixtures of these fillers. Preferred combinations of fillers are: wollastonite with glass fibers, with mixing ratios of 5: 1 to 1: 5 being preferred.

Antioxidants that can be used individually or as mixtures can also be used. Sterically hindered phenols, for example, are suitable as antioxidants. Suitable sterically hindered phenols are in principle all compounds with a phenolic structure which have at least one sterically demanding group on the phenolic ring.

Preferably, e.g. Compounds of the formula

in which mean:

R ¹ and R ^{2 are} an alkyl group, a substituted alkyl group or a substituted triazole group, where the radicals R ¹ and R ^{2 may be the} same or different and R ^{3 is} an alkyl group, a substituted alkyl group, an alkoxy group or a substituted amino group.

Antioxidants of the type mentioned are described for example in DE-A 27 02 661 (US-A 4 360 617).

Another group of preferred sterically hindered phenols is derived from substituted benzene carboxylic acids, in particular from substituted benzene propionic acids.

Particularly preferred compounds from this class are compounds of the formula

wherein R ^4, R ^5, R ⁷ and R ⁸ Cι-C ₈ independently of one another - represent alkyl groups which may in turn be substituted (at least one of which is a bulky group), and R ⁶ is a divalent aliphatic radical having 1 to 10 C Atoms means that the main chain can also have CO bonds.

Examples include sterically hindered phenols:

2,2'-methylene-bis- (4-methyl-6-tert-butylphenol), 1,6-hexanediol-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate ], Pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], distearyl-3,5-di-tert. -butyl-4-hydroxybenzylphosphonate, 2, 6, 7-trioxa-l-phosphabicyclo- [2.2.2] oct-4-yl-methyl-3, 5-di-tert. -butyl-4-hydroxyhydrocinnamate, 3, 5-di-tert. -butyl-4-hydroxyphenyl- 3, 5-distearyl-thiotriazylamine, 2- (2 '-hydroxy-3' -hydroxy-3 ', 5' -di-tert.-butylphenyl) -5-chlorobenzotriazole, 2, 6- Diet. -butyl-4-hydroxymethylphenol, 1,3, 5-trimethyl-2,, 6-tris (3, 5-di-tert-butyl-4-hydroxybenzyl) benzene, 4,4'-methylene-bis- (2, 6-di-tert-butylphenol), 3, 5-di-tert. - Butyl-4-hydroxybenzyl-dimethylamine, N, N '-hexamethylene-bis- 3, 5-di-tert. -butyl-4-hydroxyhydrocinnamide (Irganox 1098 from Ciba-Geigy), 3- (3-tert-butyl-4-hydroxy-5-methyl-phenyl) -N- (6- (3- (3-tert. -butyl-4-hydroxy-5-methylphenyl) propionylamino) hexyl) propionamide and N, N 'bis (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) -hydrazine (Irganox MD 1024 from Ciba-Geigy). Have proven to be particularly effective and are therefore preferably used 2,2'-methylene-bis- (4-methyl-6-tert-butyl-phenyl), 1,6-hexanediol-bis- [3,5-di- tert. - Butyl-4-hydroxyphenyl) propionate (Irganox® 259 from Ciba-Geigy), pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (Irganox® 1010 or Ciba-Geigy), diethylene glycol bis- [3- [3- (tert-butyl) -4-hydroxy-5-methylphenyl] propionate], or triethylene glycol bis- [3- (3- (tert. butyl) -4-hydroxy-5-methylphenyl] propionate] (Irganox® 245 from Ciba-Geigy), which is particularly suitable.

In addition to sterically hindered phenols, antioxidants with a lactone structure can also be used. Examples of this are the 3-arylbenzofuranones described in DE-PS-4432732 or the benzofuran-2-ones described in EP 644190. A combination of the sterically hindered phenols described above, such as. B. triethylene glycol bis- [3- (3- (tert-butyl) -4-hydroxy-5-methylphenyl] propionate] (Irganox® 245 from Ciba-Geigy) and one or more 3-

Arylbenzofuranones, such as. B. 3- (3, 4-Dimethylphenyl) -5, 7- di-tert. -butyl-3H-benzofuran-2-one.

The antioxidants, which can be used individually or as mixtures, are usually in an amount of up to 2% by weight, preferably from 0.005 to 2% by weight, in particular 0.1 to 1% by weight, based on the total weight of the molding compounds included.

In some cases, sterically hindered phenols with no more than one sterically hindered group ortho to the phenolic hydroxyl group have proven to be particularly advantageous; especially when assessing the color stability when stored in diffuse light over long periods of time. These additives can be present in a wide variety of amounts in the molding composition according to the invention, the amount of the particular additive (ii) used in each individual case depending on the particular useful technical effect that is to be achieved with it. The additives (ii) are expediently used in the molding composition according to the invention in the customary amounts known from the prior art of up to 60% by weight, amounts of from 0.01 to 50% by weight, based on the weight of the components (i ), (ii) and (iii) are particularly advantageous.

Component (iii)

The essential component for the invention of the reinforced or unreinforced polyoxymethylene molding compositions according to the invention is that as an additive for

Nucleation and polymeric plastic material used to improve the thermal stability (iii). Component (iii) is therefore an essential component.

The polymeric plastic material (iii) is in the molding composition according to the invention in an amount of 0.01 to

2 parts based on 100 parts of (i) + (ii). It is generally not advisable to increase the proportion of the polymeric material (iii) in the molding composition according to the invention by more than 2 parts, based on 100 parts (i) + (ii), because the advantages which can still be achieved thereby , no longer justify the higher consumption of polymeric material (iii). In addition, the polymeric material (iii) and the molding composition according to the invention may separate under certain circumstances. In contrast, the amount of polymeric material (iii) in the molding composition according to the invention should not be less than 0.01 part, because otherwise the advantageous technical effects caused by the polymeric material (iii) cannot always fully meet the requirements of practice. Accordingly, it is the range from 0.01 to 2 parts around an optimum, within which the proportion of the polymeric material (iii) in the molding composition according to the invention varies and can be adapted to the other essential constituents of the molding composition according to the invention used in each case. Within this preferred range, a narrower window is particularly useful, so that the molding composition according to the invention is characterized in a particularly preferred embodiment in that (iii) in an amount of 0.02 to 1 part, based on the sum (i) + (ii) calculated as 100 parts, is contained in the molding compound. Within this particularly expedient range, within which the molding composition according to the invention is particularly advantageous and is outstandingly suitable for the production of moldings and foils, is the range from 0.05 to 0.5 parts, again based on the sum (i) + (ii ), which is calculated as 100 parts, to be emphasized because such a proportion of polymeric plastic material (iii) results in an excellent application profile of the relevant molding composition according to the invention. This means that the amount of polymeric plastic material (iii) as a low-yellowing additive for nucleating and improving the thermostability of reinforced or unreinforced polyoxymethylene molding compositions with regard to the cost of materials on the one hand and the advantageous technical effect achieved on the other hand is excellently balanced and is therefore particularly preferred according to the invention.

In principle, the polyoxymethylene molding composition according to the invention can have the constituents (i), (ii) and (iii), which is intended to mean that other constituents not mentioned in the description may also be present in the polyoxymethylene molding composition. In a particularly preferred embodiment, however, the molding composition consists of the three components (i), (ii) and (iii) mentioned. As already stated, (iii) is a copolymer which can be obtained by polymerization in solution or polymerization in bulk (bulk polymerization). Solution polymerization is understood to mean a polymerization process in which monomers in a solvent according to the methods known for solution polymerizations, such as. B. in Ullmann's Encyclopedia of Industrial Chemistry, 4th edition, Verlag Chemie, vol. 19, p. 112, polymerized continuously or discontinuously. Under bulk polymerization is a

Polymerization process understood, in which monomers are polymerized without solvent, so that the polymerization reaction takes place in bulk or in bulk.

The components AI) and A2) of the polymer (iii)

Component AI) is a compound which has at least two polymerizable C =C double bonds in the molecule. Component AI) can consist of one or more such compounds. Therefore, in a particular variant of the invention (iii) is a copolymer which can be obtained by solution polymerization or bulk polymerization of a mixture, in which

AI) consists of 0.1-100 parts of one or more crosslinkers with at least two polymerizable carbon-carbon double bonds.

Component A2), which can also be used to obtain the polymer according to the invention (component (iii)), is one or more (meth) acrylates. The term “(meth) acrylates” is understood in principle to mean esters of acrylic acid and also esters of methacrylic acid which have a polymerizable CC double bond in the molecule. Component A2) can consist of one or more methacrylates. These can optionally have one or more acrylates.

Therefore, in a particular variant of the invention (iii) is a copolymer which can be obtained by solution polymerization or bulk polymerization of a mixture, in which

A2) 0-99.9 parts of one or more methacrylates of the general formula I

_/ CH ₃ CH ₂ = C ^(J) 'COOR ¹ where R is a linear, cyclic or branched

Is an alkyl radical having 1 to 30 carbon atoms or is a linear or branched hydroxyalkyl radical having 1 to 30 carbon atoms or a linear or branched alkylene radical having 1 to 30

Is carbon atoms or is a linear or branched epoxyalkyl radical having 1 to 30 carbon atoms or is a linear or branched alkylene glycol alkyl ether radical having 2 to 100 carbon atoms or is a linear or branched alkylene glycol radical having 2 to 100 carbon atoms or is an alkoxy radical or is a benzyl radical or a furfuryl or tetrahydrofurfuryl radical, and / or

0 - 99.9 parts of one or more acrylates of the general formula II

CH ₂ = CH (II), COOR ² wherein R is a cyclic or linear or branched alkyl radical having 1 to 30 carbon atoms or a linear or branched Hydroxyalkyl radical having 1 to 30 carbon atoms means a linear or branched alkylene radical having 1 to 30 carbon atoms or a linear or branched epoxyalkyl radical having 1 to 30 carbon atoms or a linear or branched alkylene glycol alkyl ether radical having 2 to 100 carbon atoms or a linear or branched Alkylene glycol radical having 2 to 100 carbon atoms or a benzyl radical or a furfuryl or tetrahydrofurfuryl radical is, where AI) and A2) together can give 0.1-100 parts and the sum of the parts AI), A2) and B ) Results in 100.

Among the compounds of the formula I, those in which R ^{1 is} methyl, ethyl and / or propyl, butyl, pentyl and / or hexyl are particularly preferred in the context of the invention. Mixtures of compounds in which R ² in the general formula II is methyl, ethyl, propyl, butyl, pentyl and / or hexyl are furthermore particularly expedient.

The person skilled in the art basically understands the compounds referred to as crosslinking agents or crosslinking monomers AI) to be all common compounds which can be used for crosslinking in the polymerization. In an incomplete list, this includes a. Methacrylic anhydride, allyl methacrylate, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, tetraethylene glycol dimethacrylate,

Polyethylene glycol dimethacrylate, 1, 3-butanediol dimethacrylate, 1, 4-butanediol dimethacrylate, 1, 3-butanediol diacrylate, 1,4-butanediol diacrylate, 1, 6-hexanediol dimethacrylate, hexanediol diacrylate, glycerol-1, 3-dimethacrylate, neopyl acrylate, neopentyl acrylate, neopentyl acrylate, neopentyl acrylate, neopent Neopentyl glycol ethoxylate diacrylate, neopentyl glycol ethoxylate dimethacrylate, diurethane dimethacrylate, trimethylolpropane trimethacrylate,

Trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, pentaerythritol trimethacrylate, dipentaerythritol hexaacrylate, dipentaerythritol pentaacrylate, polyethylene oxide dimethacrylate, divinylbenzene, 1, 5-hexadiene, 1, 4-0ctadylphenyl, 1, 7-0ctadylphenyl, dienylimate '-Methylene-to-

(acrylic acid amide), N, N '-methylene-bis- (methacrylic acid amide), ethylene glycol divinyl ether, triethylene glycol divinyl ether, tetraethylene glycol divinyl ether, butanediol divinyl ether, hexanediol divinyl ether, polyethylene oxide divinyl ether or trimethylol propane trivinyl ether.

Component B) of the polymer (iii)

The (meth) acrylamides and / or to be used as component B) in the context of the invention

Dialkylaminoalkyl acrylates and / or dialkylaminoalkyl methacrylates are generally known to the person skilled in the art. In a preferred embodiment of the molding composition according to the invention, component B)

Acrylamide and / or methacrylamide and / or

Dimethylaminoethyl methacrylate used. The amount of component B) in the polymer (iii) is in the range from

0 - 99.9 parts, where AI), A2) and B) together give 100 parts.

Component C) of the polymer (m)

Another component C) which can be used for the polymerization to produce the copolymers (111) according to the invention are 0 to 10 parts of molecular weight regulator based on 100 parts of AI) + A2) + B). Basically, this includes all compounds familiar to the person skilled in the art which can be used to regulate the molecular weight in solution polymerization. In an incomplete payment, this may include a. 4-methyl-2,4-diphenylpentene (1) (1,1 - (1,1-dimethyl-3-methylene-1,1-propenedyl) -bisbenzene, α-

Methylstyrene), or aliphatic mercapto compounds, such as. B. ethyl mercaptoacetate, 2-ethylhexyl mercaptoacetate, methyl 3-mercaptopropionate, 2-ethylhexyl mercaptopropionate, trimethylolpropane trimercaptoacetate, glycol dimercaptoacetate, pentaerythritol tetrakis mercaptoacetate, 1-propanotholol, n-propanodolol, n-propanetholol, 2-propanodolol, 2-propanodolol. -Dodecyl mercaptan.

Of the aforementioned compounds, n-dodecyl mercaptan is particularly preferred. An advantage of using molecular weight regulators is the generation of stable ones

End groups in the copolymer, which significantly increase the thermal stability of the copolymeπsats (m) compared to unregulated.

Component D) of the polymer (m)

Another component, which may be up to 5 parts based on 100 parts of AI) + A2) + B) in the mixture which is used to produce the copolymers of the invention (component (m)), and radical polymerization initiators. Although the polymerization reaction can in principle be triggered in any manner familiar to the person skilled in the art (for example by radiation or the like), initiation with radical-forming polymerization initiators is preferred. In addition to the classic connections that can be used Azo initiators such as azobisisobutyronitrile (AIBN) or 1, 1-azobiscyclohexane carbonitrile, including aliphatic peroxy compounds, such as. B. tert. -Amylperoxyneodecanoate, tert. -Amylperoxypivalat, tert. Butyl peroxyneodecanoate, tert. -Butyl peroxypivalate, tert. -Amylperoxy-2-ethylhexanoate, tert. -Butylperoxy-2-ethylhexanoate, tert. -Amylperoxy-3, 5.5, - trimethylhexanoate, ethyl-3, 3-di- (tert.amylperoxy) - butyrate, tert. Butyl perbenzoate, tert. -Butyl hydroperoxide, decanoyl peroxide, lauroyl peroxide, benzoyl peroxide and any mixtures of the compounds mentioned. Of the aforementioned compounds, lauroyl peroxide, azobisisobutyronitrile, tert. -Amylperoxyneodecanoate and tert. -Butylperoxypivalat particularly preferred. Azobisisobutyronitrile and lauroyl peroxide are particularly preferred.

With regard to the invention, a molding composition is very particularly preferred which comprises a copolymer (iii) which can be obtained by bulk polymerization or solution polymerization

30 - 90 parts AI),

0 - 60 parts A2),

10 - 50 parts B),

0.5 - 5 parts C) and

0.1 - 2 parts D),

contains, where AI) + A2) + B) must give 100 parts (wt / wt).

Molding compositions in which Al) trimethylolpropane triacrylate, A2) methyl methacrylate, B) methacrylamide, C) n-dodecyl mercaptan and D) azobis (isobutyronitrile) or are also extremely preferred

AI) trimethylolpropane trimethacrylate, A2) methyl methacrylate,

B) methacrylamide, C) n-dodecyl mercaptan and

D) Azobis (isobutyronitrile) or

AI) pentaerythritol tetraacrylate, A2) methyl methacrylate, B) methacrylamide, C) n-dodecyl mercaptan and

D) azobis (isobutyronitrile) or Al) dipentaerythritol penta- / hexa-acrylate, A2) methyl methacrylate, B) methacrylamide,

C) n-dodecyl mercaptan and D) azobis (isobutyronitrile).

The proportions of component (iii) in an amount of

0.02-1 part, preferably 0.05-0.5 part, based on the sum (i) + (ii), calculated as 100 parts in the molding composition, are also extremely preferred.

The invention also relates to a process for producing a shaped body or a film from a molding material

(1) Melting and mixing the constituents of the molding composition in an extruder at 150 to 260 ° C

and

(2) shaping processing of the resulting molding compound to give the molding or film in question,

wherein a molding compound is used which contains a reinforced or unreinforced polyoxymethylene molding compound according to the invention or which consists of such a molding compound.

Another aspect of the invention relates to the use of copolymers (iii), which by

Bulk or solution polymerization of a mixture of

AI) 0.1-100 parts of one or more crosslinkers with at least two polymerizable carbon-carbon double bonds

A2) 0 - 99.9 parts of one or more acrylates and / or methacrylates B) 0-99.9 parts of one or more acrylamides and / or methacrylamides and / or dialkylaminoalkyl acrylates and / or dialkylaminoalkyl methacrylates

C) based on 100 parts of A) + B)> 0.2 to 10 parts of molecular weight regulator and

D) based on 100 parts of A) + B) up to 5 parts of free-radical polymerization initiators,

is available

where all amounts relate to parts by weight (wt / wt) and AI), A2) and B) must total 100 parts, for the simultaneous stabilization and nucleation of molding compositions which contain polyoxymethylene homo- and / or copolymers.

The use of copolymers (iii) is preferred in an amount of 0.01 to 2 parts based on 100 parts of molding composition, the 100 parts being calculated without the copolymers used for nucleation and thermal stabilization.

The invention further relates to films, moldings and semi-finished products made from molding compositions according to the invention.

The polymeric materials (iii) to be used according to the invention are produced continuously or batchwise by the customary and known methods of free-radical-initiated bulk polymerization or solution polymerization.

In terms of method, the production of the molding composition according to the invention has no major particularities. Rather, it is obtained by the customary and known method of producing molding compositions. For this purpose, components (i), (ii) and (iii) of the molding composition according to the invention can be prepared individually or in the form of one or more Mixtures are fed to a suitable mixing device and mixed there at temperatures of 0 to 260 ° C. It is advantageous here to intensively mix components (i), (ii) and (iii) of the molding composition according to the invention at temperatures from 0 to 150 ° C., preferably from 0 to 50 ° C., the resulting pre-prepared mixture in an extruder , preferably a multi-shaft extruder, which may be equipped with a degassing device, and melt at temperatures of 150 to 260 ° C, preferably 200 to 250 ° C, degas the resulting melt and extrude and then discharge it from the extruder in question . The molding composition according to the invention obtained in this way can be granulated after cooling. The resulting granules can be stored temporarily or used directly for the production of films or moldings, the customary and known methods of blow molding and injection molding being suitable for the production of the films and moldings from the molding composition according to the invention.

As the examples illustrate, compared to known molding compositions, the molding compositions according to the invention have, in addition to good mechanical properties, an improvement in the temperature resistance and a significantly lower tendency to discoloration. The molding composition according to the invention is therefore extremely suitable for the production of films and moldings. The moldings are advantageously used in the automotive, electrical appliance and electronics industries.

In the context of the invention, alkyl radicals denote linear or arbitrarily branched alkyl groups which each have the number of carbons indicated. It should be stated that the residues should also be disclosed, the size of which lies between the specifically stated carbon numbers. All conceivable constitutional isomers are among the to subscribe the specified scope. The same applies to an alkylene group.

AC ₆ to C ₁₂ aryl group denotes an aromatic radical having 6 to 12 carbon atoms. These are preferably the phenyl and naphthyl radical. The same applies to an arylene group.

Halogen in the context of the invention means fluorine, chlorine, bromine, iodine.

Examples

Examples of the present invention are shown below, but it is a matter of course that the present invention is not limited thereto.

The following examples serve to illustrate the subject matter of the invention.

1. First, the general implementation of a

Solution polymerization and bulk polymerization for the preparation of copolymers which can be used according to the invention are described, it being understood that the implementation of the solution polymerization and bulk polymerization is not restricted to the process steps and apparatuses described under 1.1 to 1.3. For the entire description, the term “copolymers” encompasses a polymer which has at least 2 different monomers, in particular also terpolymers, etc. The details of the formulation, process parameters and specifications required for the preparation of the examples according to the invention can be found in the tables below. 1.1 equipment

a) 500 mL HWS double jacket vessel with anchor stirrer, Pt 100 temperature measurement, reflux condenser and thermostat

or

b) Mold consisting of 2 glass plates, between which a plastic piping is inserted for sealing, the distance between the glass plates being controlled by the piping diameter and the piping comprising three sides of the mold and the fourth side remaining open or closed after filling with piping becomes. To prevent the polymer from sticking to the glass or the piping, the glass plates are covered with a release film (e.g. "Hostaphan RV 36 / Putz). The shape is applied to three

Pages fixed with special brackets. The glass mold is heated to the desired polymerization temperature by introducing the glass mold into heated water baths or heated ovens of suitable size with temperature control.

1.2 Approach

The type and concentration of the input materials can be found in the respective recipe.

The reaction mixture consists of: monomers, regulators, initiators and, if necessary, solvents.

1.3 Implementation

The polymerization is divided into 4 general steps A to D, the processing of which can vary depending on the specifications in the respective recipe. Step A:

Monomers, regulators and any solvents are placed in the polymerization vessel and dissolved with stirring at room temperature or elevated temperature.

Step B:

The initiator is added and the solution is heated to 70 ° C. by means of a thermostat. The temperatures of the heating jacket and, if applicable, of the reaction mixture are determined by means of a sensor and recorded on the temperature recorder.

Step C:

After the end of the polymerization, the reactor contents are brought to room temperature and the copolymer obtained is separated off from any supernatant solvent.

Step D:

Drying the polymer block or the viscous polymer solution or the failed polymer block and crushing the polymer material (m) in a suitable Retsch impact cross mill SK 1 (6 mm sieve plate) and then in a Retsch Ultra centrifugal mill ZM 1 through a 0.25 mm sieve (cooled with liquid nitrogen). Some samples were additionally ground on an impact mill with pin disc inserts (from Bauermeister) and screened and fractionated.

1.4 Analytics

For some polymers, the

Glass transition temperature determined by means of differential scanning g calorimetne (DSC). Essential data and results for copolymers (iii) are given in Table 1.

Table 1

The material composition of the thermal stabilizers used according to the invention (iii!

Explanations :

MMA = methyl methacrylate AIBN azobis (isobutyronitrile)

MAA = methacrylamide n-DDM n-dodecyl mercaptan

BDMA = butanediol dimethacrylate EtOH ethanol

EGDMA = iProp isopropanol, ethylene glycol dimethacrylate

TMPTMA = trimethylolpropane trimethacrylate

3. Production and Properties of Molding Compounds According to the Invention (Examples Nos. 1 to 30) and Not According to the Invention (Comparative Experiments VI to V3):

3.1 General test instructions:

.. In the examples No. 1 to No. 30 and the comparative experiments VI to V3 each case, a thermally undegraded polyoxymethylene copolymer H20-00 or N20-00 (MVR = 1.8 to 4.0 cm ^3/10 minutes; determined according to DIN ISO 1133 at 190 ° C and a contact force of 2.16 kg), which had been produced from a mixture of 97.3 wt .-% trioxane and 2.7 wt .-% butanediol formal and which was still about 5 wt. -% unreacted trioxane and about 3 wt .-% thermally unstable formaldehyde adduct, mixed with different amounts of additives (B) and additives (C) for thermal stabilization in a dry mixer at a temperature of 23 ° C. The resulting prefabricated mixtures were introduced at a temperature of 23 ° C in a twin-screw extruder with a degassing device (type ZSK 28 from Werner and Pfleiderer, Stuttgart), homogenized at 180 to 230 ° C and degassed, after which the homogenized mixture through a nozzle as a strand was pressed out and granulated.

3.2 To test the thermal stability, the

The rate of solidification and tendency to discolouration of the polyoxymethylene samples were determined:

GV (N ₂ 2 h): The weight loss in% by weight of a sample of 1.2 g of granules after heating for two hours at 222 ° C. under a nitrogen atmosphere; GV (air 2 h): Weight loss in Ge .- a sample of 1.2 g of granules after heating for two hours at 222 ° C in air;

Isothermal crystallization time t ₂ : samples of 3.0 mg each are in an Al crucible with a perforated

Weighed the lid and heated it to 190 ° C at a heating rate of 40 K / min in a differential scanning calorimeter (type Mettler DSC 820), held it at this temperature for 5 min and then cooled it to 149 ° C at a cooling rate of 30 K / min and then kept at this temperature. Now the time until the maximum of the heat of crystallization released is reached, calculated from the point in time at which 149 ° C. is reached. This isothermal crystallization time is the time in s from reaching the crystallization temperature (149 ° C) to the maximum of the exothermic crystallization peak (= complete crystallization).

CieLab values: Colorimetric determination of the color distances L *, a * and b * (CieLab color coordinates) of the granules after extrusion at the time 2 hours after storage in a circulating air dryer at 140 ° C according to DIN 6174 (ASTM E 1347). In addition, some of the samples pretreated in this way are then stored at 140 ° C. for 100 h and the CieLab color coordinates are determined again.

Table 2 gives an overview of the molding compositions produced according to the invention and not according to the invention. The results of the above tests are summarized in Table 3. Table 2

The material composition of the molding compositions not according to the invention (Comparative Examples VI to V3) and of the molding compositions according to the invention (Example No. 1 to No. 30).

cn

Table 2 continued

r

Table 2 continued

Table 2 continued

n ^

Table 3

Thermal stability, isothermal crystallization time, melt viscosity and CieLab color coordinates of the molding compositions not according to the invention (comparative examples VI to V3) and the molding compositions according to the invention (examples No. 1 to No. 30).

c

Table 3 continued

Table 3 continued

Table 3 continued

c o

Claims

claims

1. Having polyoxymethylene molding composition

(i) at least one polyoxymethylene homo- and / or copolymer,

(ii) at least one common additive and

(iii) at least one polymeric plastic material as

Additive, which also serves to nucleate and improve thermal stability,

characterized in that

component (iii) by polymerization in solution or substance from a mixture of

D) based on 100 parts of AI) + A2) + B) up to 5 parts of radical polymerization initiators is available, and that

(iii) in an amount of 0.01 to 2 parts based on the sum of (i) + (ii)

is contained in the molding compound, all amounts being in parts by weight (wt / wt) relate and AI), A2) and B) must total 100 parts.

2. Molding compound consisting of (i), (ii) and (iii).

3. Molding composition according to claim 1 and / or 2,

characterized in that

(iii) is a copolymer that by

Solution polymerization or bulk polymerization of a mixture is obtainable, wherein

AI) consists of 0.1-100 parts of one or more crosslinkers with at least two polymerizable carbon-carbon double bonds,

A2) from 0 to 99.9 parts of one or more methacrylates of the general formula I

wherein R ^{1 is} a cyclic or linear or branched alkyl radical having 1 to 30

Is carbon atoms or is a linear or branched hydroxyalkyl radical having 1 to 30 carbon atoms or is a linear or branched alkylene radical having 1 to 30 carbon atoms or is a linear or branched epoxyalkyl radical having 1 to 30 carbon atoms or is a linear or branched alkylene glycol alkyl ether radical having 2 to

100 carbon atoms or represents a linear or branched alkylene glycol radical having 2 to 100 carbon atoms or a benzyl radical means or represents a furfuryl or tetrahydrofurfuryl radical,

and or

from 0 - 99.9 parts of one or more acrylates of the general formula II

CH ₂ = CH (II), COOR ²

wherein R ^{2 is} a cyclic or linear or branched alkyl radical having 1 to 30

Is carbon atoms or a linear or branched hydroxyalkyl radical having 1 to 30

Is carbon atoms or is a linear or branched alkylene radical having 1 to 30 carbon atoms or is a linear or branched epoxyalkyl radical having 1 to 30 carbon atoms or is a linear or branched alkylene glycol alkyl ether radical having 2 to 100 carbon atoms or is a linear or branched alkylene glycol radical having 2 is up to 100 carbon atoms or is a benzyl radical or is a furfuryl or

Tetrahydrofurfuryl radical means

consists,

where AI) and A2) together can give 1 - 100 parts and the sum of parts AI), A2) and B) gives 100.

Molding composition according to claim 3, characterized in that

R ^{1 is} methyl, ethyl, propyl, butyl, pentyl and / or hexyl.

5. Molding composition according to claim 3 or 4, characterized in that

R ^{2 is} methyl, ethyl, propyl, butyl, pentyl and / or hexyl.

6. Molding composition according to one or more of the preceding claims, characterized in that

AI) ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, tetraethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, 1, 3- butanediol dimethacrylate, 1, 4-butanediol dimethacrylate, 1, 3-butanediol diacrylate, 1, 4-butanediol diacrylate, 1,6-hexanediol dimethacrylate, hexanediol diacrylate, Glycerol-1,3-dimethacrylate, neopentylglycol dimethacrylate, neopentylglycol diacrylate, neopentylglycol ethoxylate diacrylate, neopentylglycol ethoxylate dimethacrylate, diurethane dimethacrylate,

Trimethylolpropane trimethacrylate,

Trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, pentaerythritol trimethacrylate, dipentaerythritol hexaacrylate dipentaerythritol pentaacrylate, polyethylene oxide dimethacrylate, divinylbenzene, 1,5-

Hexadiene, 1, 7-octadiene, 1, 4-butylene dimethacrylate, 1,4-butanediol diacrylate, bisphenol-A-dimethacrylate, polybutanediol dimethacrylate, N, N '-methylene-bis- (acrylic acid amide), N, N' -methylene-bis- (methacrylic acid amide), ethylene glycol divinyl ether, triethylene glycol divinyl ether,

Tetraethylene glycol divinyl ether, butanediol divinyl ether, hexanediol divinyl ether, polyethylene oxide divinyl ether and / or trimethylolpropane trivinyl ether.

7. Molding composition according to one or more of the preceding claims, characterized in that AI) butanediol dimethacrylate, trimethylolpropane trimethacrylate,

Trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, pentaerythritol trimethacrylate, dipentaerythritol hexaacrylate, dipentaerythritol pentaacrylate and / or trimethylolpropane trivinyl ether.

8. Molding composition according to one or more of the preceding claims, characterized in that

B) is acrylamide and / or methyl acrylamide and / or dimethylaminomethyl methacrylate.

9. Molding composition according to one or more of the preceding claims, characterized in that

C) is n-dodecyl mercaptan.

10. Molding composition according to one or more of the preceding claims, characterized in that

D) Lauryl peroxide and / or azobis (isobutyronitrile) and / or tert. Amyl peroxy neodecanoate and / or tert-butyl peroxypivalate.

11. Molding composition according to one or more of claims 3-10, characterized in that (iii) is a copolymer which is obtainable by bulk polymerization or solution polymerization from

30 - 90 parts AI), 0 - 60 parts A2), 5 - 50 parts B), 0.5 - 5 parts C) and 0.1 - 2 parts D),

where AI) + A2) + B) must give 100 parts (wt / wt).

12. Molding composition according to claim 11, characterized in that

AI) trimethylolpropane triacrylate, A2) methyl methacrylate,

B) methacrylamide, C) n-dodecyl mercaptan and D) azobis (isobutyronitrile).

13. Molding composition according to claim 11, characterized in that AI) trimethylolpropane trimethacrylate, A2) methyl methacrylate, B) methacrylamide,

C) n-dodecyl mercaptan and D) azobis (isobutyronitrile).

14. Molding composition according to claim 11, characterized in that

AI) pentaerythritol tetraacrylate, A2) methyl methacrylate, B) methacrylamide, C) n-dodecyl mercaptan and D) azobis (isobutyronitrile).

15. Molding composition according to claim 11, characterized in that AI) dipentaerythritol penta- / hexa-acrylate, A2) methyl methacrylate, B) methacrylamide, C) n-dodecyl mercaptan and D) azobis (isobutyronitrile).

16. Molding composition according to claim 11, characterized in that

AI) trimethylolpropane triacrylate, A2) methyl methacrylate, B) dimethylammoethyl methacrylate, C) n-dodecyl mercaptan and D) azobis (isobutyronitrile).

17. Molding composition according to claim 11, characterized in that AI) trimethylolpropane trimethacrylate, A2) methyl methacrylate, B) dimethylaminoethyl methacrylate, C) n-dodecyl mercaptan and D) azobis (isobutyronitrile).

18. Molding composition according to claim 11, characterized in that

AI) pentaerythritol tetraacrylate, A2) methyl methacrylate, B) dimethylaminoethyl methacrylate, C) n-dodecyl mercaptan and D) azobis (isobutyronitrile).

19. Molding composition according to claim 11, characterized in that AI) dipentaerythritol penta- / hexa-acrylate, A2) methyl methacrylate,

B) dimethylaminoethyl methacrylate, C) n-dodecyl mercaptan and D) azobis (isobutyronitrile).

20. Molding composition according to one of the preceding claims, characterized in that (iü) in an amount of 0.02-1 part, preferably 0.05-0.5 part, based on the sum (i) + (ii) calculated as 100 parts are contained in the molding compound.

21. Process for the production of a shaped body or a film from a molding material

and

(2) shaping processing of the resulting molding compound to give the molding or film in question, characterized in that a molding composition is used which contains a reinforced or unreinforced polyoxymethylene molding composition according to one of Claims 1 to 20 or which consists of such a molding composition.

22. Use of copolymers which by bulk polymerization or solution polymerization of a mixture of

AI) 0.1-100 parts of one or more crosslinkers with at least two polymerizable carbon

Carbon double bonds

A2) 0 - 99.9 parts of one or more acrylates and / or methacrylates

B) 0 - 99.9 parts of one or more acrylamides and / or methacrylamides and / or

Dialkylaminoalkyl acrylates and / or dialkylaminoalkyl methacrylates

D) based on 100 parts of Ä) + B) up to 5 parts of free-radical polymerization initiators,

is available

where all amounts relate to parts by weight (wt / wt) and AI), A2) and B) together have to give 100 parts, for simultaneous stabilization and

Nucleation of molding compositions which contain polyoxymethylene homopolymers and / or copolymers.

23. Use according to claim 22 of copolymers in an amount of 0.01 to 2 parts based on 100 parts of molding material, the 100 parts without the for nucleation and thermal stabilizing copolymers are expected.

24. Shaped body and semi-finished product made of molding composition according to claims 1 to 20.

25. Film made of molding composition according to claims 1 to 20.