WO2006120218A1 - Improved method for removal of residual monomer from polyoxymethylenes - Google Patents

Abstract

The invention relates to a method for removal of unreacted residual monomers from polyoxymethylene homo- or co-polymers (POM) by degassing in a degassing device and subsequent mixing in a mixing device, characterised in that the residence time of the POM between discharge from the degassing device and introduction into the mixing device is a maximum of 60 secs.

Description

Improved process for residual monomer removal from polyoxymethylenes

description

The invention relates to a process for the removal of unreacted residual monomers from Polyoxymethylenhomo- or copolymers (POM) by degassing in a degassing and subsequent mixing in a mixing device, characterized in that the residence time of the POM between the discharge from the degassing device and the entry in the mixing device is a maximum of 60 seconds.

Furthermore, the invention relates to the use of said process during or after the preparation of polyoxymethylene homopolymers or copolymers, and to a process for the preparation of polyoxymethylene homopolymers or copolymers, characterized in that first suitable monomers are prepared in a monomer system or stored, then polymerizing the monomers in a polymerization reactor to said polymers, and during or after this polymerization, the residual monomers contained in the polymers removed by the former method.

Finally, the invention relates to the polyoxymethylene homopolymers or copolymers obtainable by the latter process.

Polyoxymethylene polymers (POM, also called polyacetals) are obtained by homo- or copolymerization of 1, 3,5-trioxane (trioxane in short), formaldehyde or other formaldehyde source. The conversion is usually not complete, but the POM crude polymer still contains up to 40% unreacted monomers. Such residual monomers are, for example, trioxane and formaldehyde, and optionally comonomers used, such as 1,3-dioxolane, 1, 3-butanediol formal or ethylene oxide. In summary, POM stands for homo- and copolymers.

The residual monomers are removed by workup by degassing from the crude polymer. According to the prior art, POM is degassed at atmospheric pressure or reduced pressure and optionally subsequently mixed with additives.

EP-A 638 599 describes a process for the preparation of polyacetals in which the residual monomers in a degassing part are vaporized by lowering the pressure. Thereafter, customary additives are mixed in a confectioning extruder.

EP-A 999 224 describes the preparation of polyacetal copolymers without addition of deactivators. In this case, the raw POM leaving the polymerization reactor falls through a "drop shaft" of unspecified length into one Mixing unit (eg extruder) and is there mixed with additives, wherein the unreacted monomers are removed before or in the mixing unit by "reduced pressure".

DE-A 31 47 309 discloses the preparation of oxymethylene polymers in the

Melting, in which the unreacted monomers are removed in a degassing and confectioning reactor and conventional additives are mixed.

The unpublished German patent application Az. 102005002413.0 dated 18.01.05 describes a process for the removal of residual monomers from POM, in which a heated POM melt is degassed under pressure. Before, during and / or after degassing, the POM may be provided with conventional additives in an extruder or other mixing device.

In the non-prepublished German patent application Az. 102005012480.1 dated 16.03.05 also discloses a process for the removal of residual monomers from POM, wherein a heated POM melt is degassed in a strand degasser. Preference is given to degassing twice (degassing pot with downstream strand degasser). Also according to this document, the POM may be provided with conventional additives before, during and / or after degassing in an extruder or other mixing device.

None of the documents mentioned gives information on the spatial or temporal distance of residual monomer removal (degassing) and addition of the additives, or the residence time of the POM between degassing and addition of additive. In particular, a maximum residence time of 60 seconds between discharge from the degassing and entry into the mixing device, or even an arrangement of the degassing directly at the mixing device, not disclosed.

The embodiments of degassing and additive mixing described in the cited prior art are not always satisfactory for demanding applications of the POM. Polyoxymethylenes may undergo undesired degradation reactions under thermal stress and shear stress associated with degassing and additive mixing, see e.g. Mikhailov et al., Plaste and Kuchchuk 1974, 653-655. As a result, the residual content of formaldehyde in the polymer may increase, and the polymer may show an undesirable intrinsic color and / or worse mechanical properties.

It was the task to remedy the disadvantages described, and to further improve the degassing and additive addition. In particular, a process should be provided with which polyoxymethylenes degas in a particularly gentle manner and can be provided with additives. Accordingly, the initially defined method for removing the residual monomers was found. In addition, the said use of this process, the aforementioned process for the preparation of the POM polymers and the POM polymers obtainable by the last-mentioned process were found. Preferred embodiments of the invention can be found in the subclaims. All pressures are absolute unless otherwise stated.

Polyoxymethylene homo- and copolymers

The polyoxymethylene homopolymers or copolymers (POM) are known as such and are commercially available. The Hσmopolymere be prepared by polymerization of formaldehyde or - preferably - trioxane; Comonomers are also used in the preparation of the copolymers.

In general, such POM polymers have at least 50 mole percent of repeating units -CH 2 O- in the polymer backbone. Polyoxymethylene copolymers are preferred, in particular those which, in addition to the repeating units -CH ₂ O-, have up to 50, preferably 0.01 to 20, in particular 0.1 to 10 mol% and very particularly preferably 0.5 to 6 mol%. at recurring units

wherein R ¹ to R ^{4 are} independently a hydrogen atom, a Ci to CU-alkyl group or a halogen-substituted alkyl group having 1 to 4 carbon atoms and R ^{5 is} a -CH ₂ -, -CH ₂ O-, a d- to C ₄ alkyl or C 1 to C ₄ haloalkyl substituted methylene group or a corresponding oxymethylene group and n has a value in the range of 0 to 3. Advantageously, these groups can be introduced into the copolymers by ring opening of cyclic ethers. Preferred cyclic ethers are those of the formula

wherein R ¹ to R ⁵ and n have the abovementioned meaning. For example, ethylene oxide, 1,2-propylene oxide, 1, 2-butylene oxide, 1, 3-butylene oxide, 1,3-dioxane, 1,3-dioxolane and 1, 3-dioxepane (= butanediol, BUFO) as cyclic Ether called as well linear oligo- or polyformals such as polydioxolane or polydioxepane called comonomers.

Also suitable are Oxymethylenterpolymerisate, for example, by reacting trioxane, one of the cyclic ethers described above with a third monomer, preferably bifunctional compounds of the formula

₂

wherein Z is a chemical bond, -O-, -ORO- (R is Cr to C ₈ -alkylene or C3 to Cβ-cycloalkylene) can be prepared.

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

End-group-stabilized polyoxymethylene polymers having predominantly C-C or -O-CH3 bonds at the chain ends are particularly preferred.

The preferred polyoxymethylene copolymers have melting points of at least 150 ^° C. and weight average molecular weights _M.sub.w in the range of 5,000 to 300,000, preferably 7,000 to 250,000. Particular preference is given to POM copolymers having a nonuniformity (M _w / M _n ) of from 2 to 15, preferably from 2.5 to 12, more preferably 3 to 9. The measurements are generally carried out by gel permeation chromatography (GPC) / SEC (size exclusion chromatography), the M _n value (number average molecular weight) is generally determined by GPC / SEC.

If appropriate, the molecular weights of the polymer can be adjusted to the desired values by the regulators customary in the trioxane polymerization, and by the reaction temperature and residence time. Suitable regulators are acetals or formals of monohydric alcohols, the alcohols themselves and the small amounts of water acting as chain transfer agents, the presence of which is generally never complete. constantly avoiding, in question. The regulators are used in amounts of from 10 to 10,000 ppm, preferably from 20 to 5,000 ppm.

Initiators (also referred to as catalysts) are the cationic initiators customary in the trioxane polymerization. Proton acids such as fluorinated or chlorinated alkyl and aryl sulfonic acids, e.g. Perchloric acid, trifluoromethanesulfonic acid or Lewis acids, e.g. Tin tetrachloride, arsenic pentafluoride, phosphoric pentafluoride and boron trifluoride and their complex compounds and salt-like compounds, e.g. Boron trifluoride etherates and triphenylmethylene hexafluorophosphate. The initiators (catalysts) are used in amounts of about 0.01 to

1,000 ppm, preferably 0.01 to 500 ppm and in particular from 0.01 to 200 ppm used. In general, it is advisable to add the initiator in dilute form, preferably in concentrations of 0.005 to 5 wt .-%. As solvents for this inert compounds such as aliphatic or cycloaliphatic Kwhlenwasser- substances, e.g. Cyclohexane, halogenated aliphatic hydrocarbons, glycol ethers, cyclic carbonates, lactones, etc. may be used. Particularly preferred solvents are triglyme (triethylene glycol dimethyl ether), 1, 4-dioxane, propylene carbonate or gamma-butyrolactone.

In addition to the initiators cocatalysts can be included. These are alcohols of any kind, e.g. aliphatic alcohols having 2 to 20 C atoms, such as t-amyl alcohol, methanol, ethanol, propanol, butanol, pentanol, hexanol; aromatic alcohols having 2 to 30 C atoms, such as hydroquinone; halogenated alcohols having 2 to 20 C atoms, such as hexafluoroisopropanol; Very particular preference is given to glycols of any type, in particular diethylene glycol and triethylene glycol; and aliphatic dihydroxy compounds, in particular diols having 2 to 6 carbon atoms, such as 1,2-ethanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,4-hexanediol, 1,4-cyclohexanediol, 1, 4-cyclohexanedimethanol and neopentyl glycol.

Monomers, initiators, cocatalyst and, if appropriate, regulators may be premixed in any way or may also be added to the polymerization reactor separately from one another.

Furthermore, the stabilizing components may contain sterically hindered phenols as described in EP-A 129369 or EP-A 128739.

The polymerization mixture is preferably deactivated directly after the polymerization, preferably without a phase change taking place. The deactivation of the initiator residues (catalyst residues) is generally carried out by adding deactivators (terminating agents) to the polymerization melt. Suitable deactivators are, for example, ammonia and primary, secondary or tertiary, aliphatic and aromatic amines, for example trialkylamines such as triethylamine, or triacetonediamine. Except- suitable are basic salts such as soda and borax, furthermore the carbonates and hydroxides of the alkali and alkaline earth metals, as well as alcoholates such as sodium ethoxide. Furthermore, alkali metal or alkaline earth metal alkyls are preferred as deactivators which have 2 to 30 C atoms in the alkyl radical. As particularly preferred metals Li ₁ Mg and Na may be mentioned, with n-butyllithium being particularly preferred.

The deactivators are usually added to the polymers in amounts of preferably 0.01 ppmw to 2 wt .-%, either as such or dissolved or suspended in water, methanol, other alcohols or other organic solvents.

Formaldehyde POM can be prepared in a customary manner by polymerization in the gas phase, in solution, by precipitation polymerization or in bulk (substance). Trioxane POMs are typically obtained by bulk polymerization using any reactors with high mixing efficiency. The reaction can be carried out homogeneously, e.g. in a melt, or heterogeneous, e.g. as polymerization to a solid or solid granules. Suitable examples are shell reactors, plowshare mixers, tube reactors, list reactors, kneaders (for example Buss kneaders), extruders with, for example, one or two screws, and stirred reactors, which reactors may have static or dynamic mixers.

In bulk polymerization, for example in an extruder, molten polymer can be used to produce a so-called melt seal towards the extruder inlet, as a result of which volatile constituents remain in the extruder. The above monomers are metered into the polymer melt present in the extruder, taken together or separately from the initiators (catalysts), at a preferred temperature of the reaction mixture of 62 to 114 ° C. The monomers (trioxane) are preferably also metered in a molten state, for example at 60 to 120 ^° C.

The melt polymerization is generally carried out at 1, 5 to 500 bar and 130 to 300 ⁰ C, and the residence time of the polymerization mixture in the reactor is usually 0.1 to 20, preferably 0.4 to 5 min. The polymerization is preferably carried out to a conversion of more than 30%, for example 60 to 90%.

In each case, a crude POM is obtained which, as mentioned, contains considerable proportions, for example up to 40%, of unconverted residual monomers, in particular trioxane and formaldehyde. Formaldehyde can also be present in the crude POM if only trioxane was used as the monomer since it can be formed as a degradation product of the trioxane. In addition, other oligomers of formaldehyde may be present, for example, the tetrameric tetroxane. Trioxane is preferably used as the monomer for the preparation of the POM, which is why the residual monomers also contain trioxane, moreover usually 0.5 to 10% by weight of tetroxane and 0.1 to 75% by weight of formaldehyde.

The process according to the invention for removing the residual monomers can be operated batchwise or, preferably, continuously.

degasing

The crude POM is degassed in a degassing device. Degassing devices (flash pots), degassing extruders with one or more screws, film extruders, thin-film evaporators, spray dryers, strand degasifiers and other conventional degassing devices are suitable as degassing devices. Degassing extruders or degassing pots are preferably used. The latter are particularly preferred.

The degassing can be carried out in one stage (in a single degassing device). Likewise, it can take place in several stages - for example in two stages - in several degassing devices, which are arranged one behind the other and / or in parallel. Preferably, the series-connected arrangement.

In the multi-stage degassing the degassing devices can be the same or different in type and size. For example, you can operate two identical Entgasungstöpfe one behind the other, or two different sized Entgasungstöpfe one behind the other, or two equal degassing extruder, or two differently dimensioned degassing extruder, or a degassing and behind a degassing extruder, or a degassing extruder and behind a degassing. The variant with two (identical or different) Entgasungstöpfen is preferred. Particularly preferred to use two different Entgasungstöpfe one behind the other, wherein the second pot has a smaller volume.

In a single-stage degassing, the pressure in the degassing device is usually 0.1 mbar to 10 bar, preferably 1 mbar to 2 bar and more preferably 5 mbar to 800 mbar, and the temperature is usually 100 to 260, preferably 115 to 230 and in particular 150 to 21O ⁰ C.

In a two-stage degassing, the pressure in the first stage is preferred

0.1 mbar to 10 bar, in particular 0.5 mbar to 8 bar and particularly preferably 1 mbar to 7 bar, and in the second stage preferably 0.1 mbar to 5 bar, in particular

0.5 mbar to 2 bar and more preferably 1 mbar to 1, 5 bar. In the case of a two-stage degassing, the temperature generally does not differ significantly from the temperatures mentioned for the one-stage degassing. The temperature of the polymer is carried out in a conventional manner by heat exchangers, double jacket, tempered static mixer, internal heat exchanger or other suitable devices. The adjustment of the pressure is also carried out in a conventional manner, for example by means of pressure control valves. The polymer may be molten or solid in the degasser.

The residence time of the polymer in the Entgasungsvörrichtung is usually 0.1 sec to 30 min, preferably 0.1 sec to 20 min. In a multi-stage degassing, these times refer to a single stage. Additional residence time can be introduced by connecting pipes. In order to minimize damage to the polymer due to thermal stresses, this additional residence time through connecting pipes is preferably at most 10 minutes.

The residual monomers liberated during degassing are separated off as vapor stream. Regardless of the design of the degassing (one or more stages, Entgasungstöpfe or extruder, etc.), the residual monomers are usually selected from trioxane, formaldehyde, tetroxane, 1, 3-dioxolane, 1, 3-dioxepan, ethylene oxide and oligomers of formaldehyde.

The residual monomers separated off by the process according to the invention (vapor stream) are drawn off in the customary manner. They can be condensed and recycled to the polymerization. The quantitative ratio of trioxane and formaldehyde in the vapor stream can be varied by adjusting appropriate pressures and temperatures. The higher the pressure, the greater the formaldehyde content in the broth stream.

Mix

After degassing in the degassing device, the POM is mixed in a mixing device. Preferably, in the mixing device, the POM is mixed with conventional additives, which are described below. Also preferably, the mixing device also serves a further degassing, see below.

As mixing devices are, for example, mixers, kneaders or - preferably - extruder. The mixing device is preferably operated continuously and is possibly temperable, wherein usually a part of the heat energy is already generated by the shear associated with the mixing process, and the remaining part is supplied by heating the mixing device.

Mixers are in particular mixers with moving tools, eg screw conveyor mixers, double spiral mixers, paddle mixers, plowshare mixers, Paddle mixer, agitator mixer (also agitator fan mixer) or rolling mills.

Suitable extruders are all conventional screw machines, in particular single-screw and twin-screw extruders (eg ZSK from Coperion or Werner & Pfleiderer), co-kneaders, Kombiplast machines, MPC kneading mixers, FCM mixers, KEX kneading screw extruders or shear roller extruders ,

The mixing device and its design, in particular the type and speed of the mixing tool and the amounts supplied and the throughput of the mixing device are chosen in a known manner such that the POM is mixed in the desired manner or the additives are incorporated in the desired manner in the POM or the POM is further degassed.

In the extruder, for example, speed, length, temperature profile along the screw (s), diameter and configuration of the extruder screw (s), for example, number and depth of flights, pitch, use and sequence of promotional (eg thrust edge), backfeeding, jamming, kneading and / or mixing elements along the screw, be varied accordingly. Preference is given to twin-screw extruders, in particular those with co-rotating screws.

During mixing, the temperature is usually 160 to 260, preferably 180 to 240 and in particular 200 to 220 ⁰ C and is adjusted with conventional heaters. For high shear mixers, cooling may be required to limit the heating of the polymer.

The pressure during mixing depends i.a. from the mixing device and the operating conditions. It is generally not critical and is for example 1 to 80, preferably 5 to 50 bar.

In a preferred embodiment, the mixing device and its operating conditions are selected in a manner known per se such that further degassing takes place in the mixing device, i. By mixing in the mixing device, the residual monomer content of the POM is lowered again. For this purpose, one can provide the mixing device with conventional degassing devices. For example, an extruder may be used which has vent openings. These may optionally be applied at reduced pressure, e.g. 50 to 800 mbar (absolute) can be operated to improve the degassing effect, and may have retention devices that prevent the escape of polymer.

From the mixing device, the polymer is withdrawn by conventional conveying elements, for example pumps, in particular melt pumps, screw conveyors or the like. fem the mixing device is not self-promoting (extruder). Subsequently, the discharged melt is usually cooled and granulated.

Dwell time between degassing and mixing

According to the invention, the residence time of the POM between the discharge from the degassing device and the entry into the mixing device is not more than 60 seconds, preferably not more than 30 seconds and more preferably not more than 10 seconds. Residence time means the mean residence time, and in the case of multi-stage degassing meant the last degassing device before the mixing device.

In one embodiment A of the invention, the polymer is withdrawn from the degassing device with a pipeline and / or customary discharge elements and conveyed into the mixing device, it also being possible, if necessary, to interpose collecting vessels or valves. Suitable delivery devices are e.g. Pumps (melt pumps, gear pumps, etc.), screw conveyors and other commonly used for promoting melt conveyor members. The residence time of the POM in the pipelines, conveying elements, collecting tanks and valves is taken together to a maximum of 60, preferably a maximum of 30 and preferably a maximum of 10 seconds.

In a particularly preferred embodiment B, the discharge of the degassing device coincides with the entry of the mixing device, i. In this case, the discharge of the degassing is mounted directly to the entry of the mixing device without intermediate collecting containers, pipes, pumps, screw conveyors, valves or other conveying devices or control devices.

In embodiment B, one can regard the mixing device as the discharge member which withdraws the POM from the degassing device. As a result, a separate discharge member for the degassing is saved, which reduces the investment and the space required by the plant and improves the economy.

In terms of apparatus, the degassing device is arranged above the mixing device so that the polymer, following gravity, falls from the degassing device into the mixing device.

As mentioned, a degasification pot is preferably used as degassing device, and preferably an extruder as mixing device. In this case, embodiment B can be realized, for example, by removing the bottom of the degassing pot and mounting the bottom open degassing pot directly onto the entry dome of the extruder. As a result, the extruder sets the bottom of the degassing The extruder acts as a Austragsorgan of Entgasungstopfs by pulling the POM from the pot. Accordingly, in this realization, the polymer is not first collected in the degassing pot, then discharged through a pump or other conveying member and conveyed through a pipeline into the extruder. Rather, the degassing is arranged on the extruder and emptied directly into the extruder.

additives

The polyoxymethylene molding compositions may, as mentioned, optionally contain further additives which are mixed in the mixing device and described below under 1) to 11). The quantities given are preferred quantities in the event that the additive in question is used at all.

1)

Talcum, a hydrated magnesium silicate of the composition Mg ₃ [(OH) 2 / Si ₄ Oio] or 3 MgO • 4 SiO 2 • H2O. These so-called three-layer phyllosilicates have a triclinic, monoclinic or rhombic crystal structure with a platelet-like appearance. Mn, Ti, Cr, Ni, Na and K can be present on further trace elements, it being possible for the OH group to be partially replaced by fluoride.

If used, talc is preferably used in amounts of from 0.01 to 2% by weight, preferably from 0.02 to 0.8% by weight and in particular from 0.03 to 0.4% by weight, based on the finished POM.

Particular preference is given to using talc whose particle sizes are 100% less than 20 μm. The particle size distribution is usually determined by sedimentation analysis and is preferably: <20 μm: 100% by weight, <10 μm: 99% by weight, <5 μm: 85% by weight, <3 μm: 60% by weight , <2 μm: 43% by weight. Such products are commercially available as Micro-Tale IT. Extra (Norwegian TaIc Minerals) available.

2)

Polyamides, in particular semicrystalline or amorphous resins, as described, for example, in the Encyclopedia of Polymer Science and Engineering, Vol. 11, pp. 315 to 489, John Wiley & Sons, Inc., 1988. In general, the melting point of the polyamide is below 225 ⁰ C, preferably below 215 ⁰ C.

Examples of these are Polyhexamethylenazelainsäureamid, Polyhexamethylensebacin- acid amide, Polyhexamethylendodekandisäureamid, poly-11-aminoundecansäureamid and bis (p-aminocyclohexyl) methane-dodekansäurediamid or obtained by ring-opening of lactams, such as caprolactam or Polylaurinlactam products. Also Polyamides based on terephthalic acid or isophthalic acid as the acid component and / or trimethylhexamethylenediamine or bis (p-aminocyclohexyl) propane as the diamine component and polyamide base resins prepared by copolymerizing two or more of the aforementioned polymers or their components are suitable.

Particularly suitable polyamides 2) which may be mentioned are mixed polyamides based on caprolactam, hexamethylenediamine, p.p'-diaminodicyclohexylmethane and adipic acid, which may additionally contain monofunctionally polymerizing compounds such as propionic acid or triacetonediamine as molecular weight-regulating components. Examples include Ultramid® 1 C or Ultramid® C31 from BASF Aktiengesellschaft.

Other suitable polyamides are sold 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, or by the amount of said monofunctionally polymerizing compounds.

The proportion of the polyamides 2) in the finished POM - if used - is usually 0.001 to 2 wt .-%, preferably 0.005 to 1, 99 wt .-%, preferably 0.01 to 0.08 wt .-%.

By the concomitant use of a polycondensation product of 2,2-di- (4-hydroxyphenyl) propane (bisphenol A) and epichlorohydrin, the dispersibility of the polyamides used can be improved in some cases.

Such condensation products of epichlorohydrin and bisphenol A are commercially available. Processes for their preparation are also known to the person skilled in the art. Tradenames of the polycondensates are Phenoxy® (Union Carbide Corporation) and Epikote® (Shell). The molecular weight of the polycondensates can vary within wide limits; In principle, the commercially available types are all suitable.

3)

Alkaline earth silicates and / or alkaline earth glycerophosphates, if used, usually in amounts of 0.002 to 2.0 wt .-%, preferably 0.005 to 0.5 wt .-% and in particular 0.01 to 0.3 wt .-%, based on the finished POM. As alkaline earth metals for the formation of silicates and glycerophosphates preferably calcium and especially magnesium have proven. Find application advantageously calcium glycerophosphate, and preferably Magnesiumglyce- pyrophosphate and / or calcium silicate, preferably magnesium silicate, wherein as alkaline earth metal silicates ^J, particularly preferred are those represented by the formula

Me • x SiO ₂ • n H ₂ O

be described in the mean

Me is an alkaline earth metal, preferably calcium or in particular 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 alkaline earth silicates or glycerophosphates 3) are advantageously used in finely ground form. Products with an average particle size of less than 100 microns, preferably less than 50 microns are particularly well suited.

Preferably used are calcium and magnesium silicates and / or calcium and magnesium glycerophosphates. For example, they can be specified by the following characteristics:

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,

SiO ₂ ratio: 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, average particle size: less than 100 μm, preferably less than 50 μm;

Calcium or magnesium glycerophosphates:

Content of CaO or MgO: greater than 70% by weight, preferably greater than 80% by weight,

Incineration residue: 45 to 65% by weight,

Melting point: greater than 300 ^° C. and average grain size: less than 100 μm, preferably less than 50 μm.

4) a) esters or amides of saturated or unsaturated aliphatic carboxylic acids having 10 to 40 carbon atoms, preferably 16 to 22 carbon atoms, with polyols or aliphatic saturated alcohols or amines having 2 to 40 carbon atoms, preferably 2 to 6 C atoms, or b) ethers derived from alcohols and ethylene oxide. The amount of these esters, amides or ether if used - is usually 0.01 to 5, preferably from 0.09 to 2 and in particular from 0.1 to 0.7 wt .-%, based on the finished POM.

The carboxylic acids may be monovalent or divalent. Examples which may be mentioned are pelargonic acid, palmitic acid, lauric acid, margaric acid, dodecanedioic acid, behenic acid and particularly preferably stearic acid, capric acid and montanic acid (mixture of fatty acids having 30 to 40 carbon atoms).

The aliphatic alcohols can be monovalent to tetravalent. Examples of alcohols are n-butanol, n-octanol, stearyl alcohol, ethylene glycol, propylene glycol, neopentyl glycol, pentaerythritol, with glycerol and pentaerythritol being preferred.

The aliphatic amines can be monovalent to trivalent. Examples of these are stearylamine, ethylenediamine, propylenediamine, hexamethylenediamine, di (6-aminohexyl) amine, with ethylenediamine and hexamethylenediamine being particularly preferred. Correspondingly, preferred esters or amides are glycerol distearate, glycerol tristearate, ethylenediamine distearate, glycerol monopalmitate, glycerol trilautate, glycerol monobehenate and pentaerythritol tetrastearate.

It is also possible to use mixtures of different esters or amides or esters with amides in combination, the mixing ratio being arbitrary.

Also suitable are polyether polyols or polyester polyols which are esterified or etherified with mono- or polybasic carboxylic acids, preferably fatty acids. Suitable products are commercially available, for example, as Loxiol® EP 728 from Henkel KGaA.

Preferred ethers 4) b), which are derived from alcohols and ethylene oxide, have the general formula RO (CHaCHaO) _n H, in which R is an alkyl group having 6 to 40 carbon atoms and n is an integer greater than or equal to 1.

Particularly preferred for R is a saturated Ci6-iβ fatty alcohol with n 50, which is commercially available as Lutensol® AT 50 from BASF.

5) non-polar polypropylene waxes, i. Polypropylene waxy character, which have a corresponding low molecular weight.

The amount of these polypropylene waxes - if used - is usually 0.05 to 10, preferably from 0.1 to 5 wt .-%, based on the finished POM. Waxes 5) have a weight average molecular weight M _{w of} from 2,000 to 60,000 (by GPC and standard polystyrene), preferably from 5,000 to 50,000, and more preferably from 10,000 to 45,000. Their softening point is preferably at least 140 ⁰ C, preferably at least 150 ⁰ C ₁ determined according to DIN EN 1427 (ring-and-ball method), their viscosity generally from 10 to 5000 mPas, preferably from 100 to 3000 mPas at 17O ⁰ C. according to DIN 53018 and their density usually from 0.87 to 0.92 g / cm ³ , preferably from 0.88 to 0.91 g / cm ³ according to DIN 53479.

Preferred waxes 5) have the form of so-called micropowders whose d ₅ o value is from 1 to 50 μm, preferably from 5 to 30 μm.

According to Ullmann's Encyclopedia of Industrial Chemistry, 6th edition, keyword 6.1.5 Polar Polyolefin Waxes, Verlag Chemie, 2000, waxes without the incorporation of polar groups (in particular of carboxyl and / or ester groups) are understood to mean nonpolar polypropylene waxes in the sense of the invention. ,

The waxes 5) can be produced in high-pressure stirred autoclaves or in high-pressure tubular reactors using regulators. Production in stirred high pressure autoclave is preferred. The stirred high-pressure autoclave are known per se, a description can be found in Ullmann's Encyclopedia of Industrial Chemistry, 5th edition, keywords: Waxes, Vol. A 28, p 146 ff., Verlag Chemie Weinheim, Basel, Cambridge, New York, Tokyo , 1996. In them predominantly the ratio length / diameter behaves at intervals of 5: 1 to 30: 1, preferably 10: 1 to 20: 1. The equally applicable high pressure tube reactors can also be found in Ullmann's Encyclopedia of Industrial Chemistry, 5th edition , Waxes, Vol. A 28, p. 146 ff., Verlag Chemie Weinheim, Basel, Cambridge, New York, Tokyo, 1996.

According to Ulimann (supra), the depolymerization of polypropylenes having higher molecular weights is customary as a further preparation method.

The commercially available waxes 5) are translucent, colorless to white powder products which give clear melts and are soluble in nonpolar solvents.

Preferred products are Licowax® PP in particular Licowax® PP 230 and PP 220 and Licowax® VP PP grades from Clariant and Ceridust® VP 6071 and the LC 525 N, LC 502 N, LC 502 NC, LC 503 N, LC 503 NC Types from Hana Corporation, Korea. 6)

Nucleating agent, if used usually in amounts of 0.0001 to 1% by weight, preferably 0.001 to 0.8 wt .-% and in particular 0.01 to 0.3 wt .-%, based on the finished POM.

Suitable nucleating agents are all known compounds, for example melamine cyanurate, boron compounds such as boron nitride, silica, talc, 2,3-dioxyquinoxaline, branched and crosslinked acetal copolymers, acetal block copolymers and pigments such as e.g. Heliogenblau® (copper phthalocyanine pigment) from BASF Aktiengesellschaft, as well as melamine-formaldehyde condensates.

7)

Fillers, if used usually in amounts of up to 50 wt .-%, preferably

5 to 40 wt .-% based on the finished POM.

For example, potassium titanate whiskers, carbon and preferably glass fibers are suitable, the glass fibers e.g. in the form of glass fabrics, mats, nonwovens and / or glass silk rovings or cut glass silk of low-alkali E glass with a diameter of 5 to 200 microns, preferably 8 to 50 microns can be used. Fibrous fillers, after incorporation, preferably have an average length of 0.05 to 1 mm, in particular 0.1 to 0.5 mm.

Other suitable fillers are, for example, calcium carbonate or glass beads, preferably in ground form or mixtures of these fillers.

8) impact-modifying polymers (hereinafter also referred to as rubber-elastic polymers or elastomers), if used usually in amounts of up to 50, preferably 0 to 40 wt .-%, based on the finished POM.

Preferred types of such elastomers are the so-called ethylene-propylene (EPM) and ethylene-propylene-diene (EPDM) rubbers. EPM rubbers generally have virtually no double bonds, while EPDM rubbers can have 1 to 20 double bonds / 100 carbon atoms.

As diene monomers for EPDM rubbers 8), for example, 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-1,5-diene and octa-1,4-diene, cyclic dienes such as cyclopentadiene, cyclohexadienes, cyclooctadienes and dicyclopentadienes 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-methyltricyclo (5.2.1.0.2.6) -3,8-decadiene or mixtures thereof. To be favoured Hexa-1, 5-diene, 5-ethylidene-norbornene and dicyclopentadiene. The diene content of the EPDM rubbers is preferably 0.5 to 50, in particular 1 to 8 wt .-%, based on the total weight of the rubber.

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

Another group of preferred rubbers 8) are copolymers of ethylene with esters of (meth) acrylic acid. In addition, the rubbers may still contain epoxy group-containing monomers. These epoxy group-containing monomers are preferably incorporated into the rubber by adding epoxy group-containing monomers of the general formulas I or II to the monomer mixture

CHR ⁸ = CH - (CHR ⁷ ) _α - CH - CHR ⁶ C)

CH ₂ = CR ¹⁰ - COO - (CH ₂ ) _p --CH - CHR ⁹ (II)

\> /

wherein R ⁶ to R ^{10 are} hydrogen or alkyl groups having 1 to 6 carbon atoms and m is an integer from 0 to 20, g is an integer from 0 to 10 and p is an integer from 0 to 5.

The radicals R ⁶ to R ⁸ preferably denote hydrogen, where m is 0 or 1 and g is 1. The corresponding compounds are allyl glycidyl ether and vinyl glycidyl ether.

Preferred compounds of the formula II are epoxy group-containing esters of acrylic acid and / or methacrylic acid, such as glycidyl acrylate and glycidyl methacrylate.

Advantageously, the copolymers consist of 50 to 98 wt .-% of ethylene, 0 to 20 wt .-% of epoxy-containing monomers and the remaining amount of (meth) acrylic acid esters.

Particularly preferred are copolymers of

50 to 98, in particular 55 to 95 wt .-% ethylene,

0.1 to 40, in particular 0.3 to 20 wt .-% glycidyl acrylate and / or glycidyl methacrylate, (meth) acrylic acid and / or maleic anhydride and

1 to 50, in particular 10 to 40 wt .-% n-butyl acrylate and / or 2-ethylhexyl acrylate. Further preferred esters of acrylic and / or methacrylic acid are the methyl, ethyl, propyl and i- or t-butyl esters. In addition, vinyl esters and vinyl ethers can also be used as comonomers.

The ethylene copolymers 8) described above can be prepared by methods known per se, preferably by random copolymerization under high pressure and elevated temperature. Corresponding methods are generally known.

Preferred elastomers 8) are also emulsion polymers, their preparation e.g. at Blackley in the monograph "Emulsion Polymerization". The emulsifiers and catalysts which can be used are known per se.

Basically, homogeneously constructed elastomers or those with a shell structure can be used. The shell-like structure is u.a. determined by the order of addition of the individual monomers; the morphology of the polymers is also influenced by this order of addition.

By way of example, as monomers for the preparation of the rubber portion of the elastomers, acrylates such as e.g. N-butyl acrylate and 2-ethylhexyl acrylate, corresponding methacrylates, butadiene and isoprene and their mixtures called. These monomers may be reacted with other monomers such as e.g. 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 (having a glass transition temperature lower than ⁰ ° C.) of the elastomers may be the core, the outer shell, or a middle peel (for elastomers having more than two shell construction); in the case of multi-shell elastomers, it is also possible for a plurality of shells to consist of a rubber phase.

In addition to the rubber phase, one or more hard components (with glass transition temperatures of more than 2O ⁰ C) on the structure of the elastomer involved, these are generally prepared by polymerization of 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. In addition, smaller proportions of other comonomers can also be used here.

In some cases, it has been found to be advantageous to use emulsion polymers 8) which have reactive groups on the surface. Such groups are, for example, epoxy, amino or amide groups, as well as functional groups, by the concomitant use of monomers of the general formula

can be introduced

where the substituents may have the following meanings:

R ^{15 is} hydrogen or a C 1 to C ₄ alkyl group,

R ^is hydrogen, a ^{C 1 to C 6} alkyl group or an aryl group, in particular

phenyl,

R ^{17 is} hydrogen, a C ₁ to C 10 alkyl, a C ₆ to C 12 aryl group or -OR ¹⁸

R ^{18 is} a Cr to Cβ-alkyl or Ce to C 12 -aryl group, which may optionally be substituted by O- or N-containing groups,

X is a chemical bond, a Cr to Cio-alkylene or C6-Ci2-arylene group or the O.

- C - Y

Y OZ or NH-Z and

Z is a Ci to Cio-alkylene or Ce to Ci2-arylene group.

The graft monomers described in EP-A 208 187 are also suitable for introducing reactive groups on the surface. Further examples which may be mentioned are 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 acrylate and (N, N-diethylamino) called ethyl acrylate.

Furthermore, the particles of the rubber phase can also be crosslinked. Examples of monomers acting as crosslinkers are buta-1,3-diene, divinylbenzene, diallyl phthalate, butanediol diacrylate and dihydrodicyclopentadienyl acrylate, and also the compounds described in EP-A 50 265.

Furthermore, it is also possible to use so-called graftlinking monomers, ie monomers having two or more polymerizable double bonds which react at different rates during the polymerization. Preferably, compounds are used in which at least one active group polymerized at about the same rate as the other monomers, while the other reactive group (or reactive groups), for example polymerized much slower (polymerize). The different polymerization rates bring a certain proportion of unsaturated double bonds in 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 grafting monomers to form chemical bonds, ie the grafted-on phase is at least partially linked to the grafting base via chemical bonds.

Examples of such graft-crosslinking monomers are allyl-containing monomers, in particular allyl esters of ethylenically unsaturated carboxylic acids, such as allyl acrylate, allyl methacrylate, diallyl maleate, diallyl fumarate, diallyl itaconate or the corresponding monoallyl compounds of these dicarboxylic acids. In addition, there are a variety of other suitable graftlinking 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 in the component 8) is up to 5 wt .-%, preferably not more than 3 wt .-%, based on the elastomers 8).

Preferred emulsion polymers 8) have a core of buta-1,3-diene, isoprene, n-butyl acrylate, ethylhexyl acrylate or mixtures thereof, optionally together with crosslinking monomers, and at least one outer shell of styrene, acrylonitrile, (meth) acrylates or their mixtures, optionally with reactive groups as described herein on.

Instead of graft polymers having a multi-shell structure, homogeneous, i. single-shell elastomers of buta-1, 3-diene, isoprene and n-butyl acrylate or copolymers thereof are used. These products can also be prepared by concomitant use of crosslinking monomers or monomers having reactive groups.

The described elastomers 8) can also be prepared by other conventional methods, e.g. by suspension polymerization.

As further suitable elastomers 8) may be mentioned thermoplastic polyurethanes which z. For example, in EP-A 115 846, EP-A 115 847 and EP-A 117 664 are described.

Of course, it is also possible to use mixtures of the rubber types listed above. 9) other customary additives and processing aids, in particular flame retardants, plasticizers, adhesion promoters, dyes and pigments. The proportion of such additives, if used, is generally in the range from 0.001 to 5% by weight, based on the finished POM.

10)

Formaldehyde scavengers. Suitable formaldehyde scavengers 10) are listed below under 10a), 10b), 10c) and 10d). The compounds mentioned under 10a), 10b) and 10c), if used, are used in amounts of 0.001 to 3, preferably 0.01 to 2 and in particular 0.1 to 1 wt .-%, based on the finished POM. The amount of compounds 10d) is mentioned below.

10a)

Amine group-containing compounds. Preferably used amine-substituted triazine compounds such as melamine (I.S.δ-triazine ^^. Θ-triamine). The amine groups may be unsubstituted (-NH2) or substituted with substituents R (-NHR or -NRΣ).

Very particular preference is given to amine-substituted triazine compounds which additionally have at least one aromatic group. Preferred triazine compounds are compounds of the general formula

wherein Ri, R ₂ and R3 are the same or different and each represent hydrogen atoms, halogen atoms, a hydroxyl group, an alkyl group, an alkoxy group, an aryl group, an arylalkyloxy group or a substituted or unsubstituted amine group with the proviso that at least one of Ri , R ₂ and R _{3 is} a substituted or unsubstituted amine group, and at least one of R ₁ , R ₂ and R ₃ is composed of a Cs-C 20 aromatic group which may be optionally substituted.

The halogen atom is, for example, chlorine or bromine, preferably chlorine. Examples of the alkyl group are those having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms. Examples of alkoxy groups are those having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms. Preferred aryl groups are the phenyl group, naphthyl group and fluorenyl group. As arylalkyloxy groups, phenylalkyloxy groups, in particular benzyloxy or phenylethyloxy groups, are preferred.

Examples of substituents on the substituted amino group include lower alkyl groups having 1 to 6 carbon atoms, such as methyl, ethyl, butyl or hexyl groups, phenyl groups, lower alkenyl groups having 3 to 6 carbon atoms, such as AIIyI or hexenyl groups, hydroxyalkyl groups 1 or 2 carbon atoms, such as hydroxymethyl or hydroxyethyl groups, and cyanoalkyl groups having 3 to 6 carbon atoms, such as cyanoethyl or cyanobutyl groups.

Examples of amine-substituted and aromatic-substituted triazine compounds include 2,4-diamino-6 (o, p, m) -chlorophenyltriazine, 2-amino-4-chloro-6-phenyltriazine, 2-amino-4,6-diphenyltriazine, 2,4- Diamino-6-naphthyltriazine, 2,4-diamino-6-fluorenyl-triazine, 2,4-diamino-6 (o, m, p) alkylphenyltriazine, where the methyl radical is preferred as a substituent, 2,4-diamino-6 ( o, m, p) methoxyphenyltriazine and 2,4-diamino-6 (o, m, p) - carboxy-phenyltriazines, N-phenylmelamine, N, N'-diphenylmelamine, wherein benzoguanamine, ie 2,4-diamino-6-phenyl-sym.-triazine, 2,4-diamino-6-benzyloxy-sym.-triazine are particularly preferred.

Particularly preferred triazine compounds contain at least two radicals R 1, R ₂ or R ₃ , which are built up from (un) substituted amino groups and / or in which the aromatic radical R 1, R ₂ or R ₃ consists of at least one phenyl ring.

Very particularly preferred as the triazine compound are the guanamines, in particular benzoguanamine.

10b) inorganic, formaldehyde-binding compounds. In this case, the binding of the formaldehyde can be carried out chemically or preferably physically, e.g. by adsorption.

Preference is given to using zeolites, ie crystalline aluminosilicates with ordered channel and cage structures. The network of such zeolites is composed of SiO ₄ and AIO ₄ tetrahedra, which are connected via the common oxygen bridges. An overview of the known structures can be found, for example, in MW Meier, DH Olson, Ch. Baerlocher, "Atlas of Zeolite Structure Types", 5th revised edition, Elsevier, London, 2001. Another listing is available on the Internet at URL http : //topaz.ethz.ch/IZA-SC/SearchRef.htm, where among other things the following structures are described: ABW, ACO, AEI, AEL, AEN, AET, AFG, AFI, AFN, AFO, AFR, AFS ₁ AFT , AFX, AFY, AHT, ANA, APC, APD, AST, ASV, ATN, ATO, ATS, ATT, ATV, AWO, AWW, BCT, BEA, BEC, BlK, BOG, BPH, BRE, CAN, CAS, CDO , CFI, CGF, CGS, CHA, CHI, CLO, CON, CZP, DAC, DDR, DFO, DFT, DOH, DON, EAB, EDI, EMT, EPI, ERI, ESV ₁ ETR, EUO ₁ FAU, FER, FRA, GIS ₁ GIU, GME, GON, GOO ₁ HEU, IFR, ISV, ITE, ITH, ITW, IWR, IWW, JBW ₁ KFI, LAU, LEV ₁ LIO, LOT, LOV ₁ LTA, LTL, LTN ₁ MAR, MAZ, MEI, MEL, MEP, MER ₁ MMFI, MFS ₁ MON, MOR, MSO, MTF, MTN ₁ MTT, MTW, MWW, NAB, NAT, NEES, NON ₁ NPO ₁ OBW ₁ OFF, OSI ₁ OSO, PAR, PAU ₁ PHI ₁ PON ₁ RHO, RON, RRO, RSN, RTE ₁ RTH ₁ ROD, RWR ₁ RWY ₁ SAO, SAS ₁ SAT ₁ SAV ₁ SBE, SBS, SBT ₁ SFE ₁ SFF, SFG ₁ SFH ₁ SFN SFO ₁ SGT ₁ SOD ₁ SSY, STF ₁ STI ₁ STT, TER, THO ₁ TONE, TSC, UEI ₁ UFI ₁ UOZ ₁ USI, UTL, VET ₁ VFI, VNI ₁ VSV ₁ WEI ₁ WHO, YUG or ZON.

Preferably, the structures BEA, FER, FAU, LTA ₁ MEL, MFI or MOR, as well as mixed structures of two or more of these types are mentioned, such as a zeolite material with MEL / MFI mixed structure. Among others, particularly preferred is an LTA-type zeolite. Very particular preference is given to zeolites which have essentially 8-ring channels (and essentially no 10- and / or 12-ring channels).

To compensate for the negative electrovalence that results from incorporation of Al (III) into the Si (IV) silicate lattice, exchangeable cations are found in zeolitic materials. In particular, depending on the method of preparation of the zeolitic material, these may be, for example, cations of sodium, potassium, lithium, rubidium or cesium. Ammonium ions may also be present as cations in the zeolitic material. Replacing these cations with protons, for example by ion exchange, gives the corresponding materials in the so-called aeid form, the H-form. Preferably, at least 75% by weight of the zeolite is not in the H form, more preferably at least 97% by weight.

The pore diameter of the zeolites is preferably in the range from 0.3 to 0.5 nm, in particular from 0.37 to 0.43 nm, determined in accordance with DIN 66134 and DIN 66135.

The particle size of the zeolites is preferably in the range of 3 to 7 .mu.m, in particular 4 to 6 .mu.m, determined according to ISO 13320 in the version of 1999-11-01. As a dispersant for determining the particle size, demineralized (VE) water was used. The apparatus used was a Malvern Mastersizer 2000 (Module Hydro 2000G). The preparation of the samples was carried out at a solids content of 1 to 2 wt .-% in water and subsequent stirring with a magnetic stirrer, stirring for 1 min. As a particle size, the size of the particles was determined at a pass of 50%.

Most preferably, the zeolite has a pore diameter in the range of 0.37 to 0.43 nm and a particle size in the range of 4.0 to 6.0 microns. The zeolite may in principle have any molar ratio Si: Al, calculated as molar ratio SiO ₂ ) AbO ₃ . Preferably, the Si: Al ratio, calculated as the molar ratio of SiOΣiAbOa, is in the range of up to 5: 1, in particular 0.9: 1 to 5: 1, particularly preferably about 1: 1.

In addition, zeolites are also suitable whose structures differ from those mentioned above, or whose pore diameters and / or particle sizes and / or Si: Al ratios and / or proportions in H form are outside the ranges mentioned.

10c) the following compounds or their derivatives (i.e., such compounds, the following

Compounds as basic body):

Allantoin (5-ureido-hydantoin);

Aminopyridines, especially 2-, 3- and 4-aminopyridine;

Poly-beta-alanine;

polyacrylamides;

Ethyl-para-aminobenzoate; Polyethylene vinyl alcohols;

Urea derivatives;

2-amino-2-methyl-1,3-propanediol;

1, 2,3-benzotriazole;

anthranilamide; sterically hindered amines (monomeric or oligomeric), e.g. the compound having CAS No. 152261-33-1, commercially available as Uvinul® 5050 H from BASF;

soy protein isolate;

Distearyl pentaerythritol diphosphite;

Casseine; and 4-aminobenzoic acid.

10d)

Polyethyleneimines. These are understood as meaning both homopolymers and copolymers which contain the grouping -CH ₂ -CH ₂ -NH-. They are, for example, according to the methods in Ullmann's Encyclopedia of Industrial Chemistry as the 6th edition, 1999 Electronic Release, Verlag VCH Weinheim, and as the 6th edition, 2000 Electronic Release, Verlag Wiley-VCH, each keyword "Aziridines", Chap. 6 "Ilses", available, or according to WO-A 94/12560 available.

It is preferable to use the polyethyleneimines 10d) - if used - in such an amount that the POM 0.01 to 500 ppmw, in particular 0.1 to 200 ppmw, more preferably 0.1 to 50 ppmw and most preferably 0.5 up to 10 ppmw of the polyethyleneimine. One can also use several polyethyleneimines; In this case, the amounts mentioned refer to the sum of all polyethyleneimines.

The ethyleneimine homopolymers are generally obtainable by polymerization of ethyleneimine (aziridine) in aqueous or organic solution in the presence of acid-releasing compounds, acids or Lewis acids. Such homopolymers are linear or preferably branched polymers. The latter generally have primary, secondary and tertiary amino groups in the ratio of, for example, about 1: 1: 0.7. The distribution of the amino groups can be determined, for example, by means of ¹³ C-NMR spectroscopy.

Comonomers used are preferably compounds which have at least two amino functions. Examples of suitable comonomers are alkylenediamines having 2 to 10 C atoms in the alkyl radical, with ethylenediamine and propylenediamine being preferred. Further suitable comonomers are diethylenetriamine, triethylenetetramine, tetraethylenepentamine, dipropylenetriamine, tripropylenetetamine, dihexamethylenetriamine, aminopropylethylenediamine and bisaminopropylethylenediamine.

In addition, crosslinked polyethyleneimines which are obtainable by reaction of polyethyleneimines with bifunctional or polyfunctional crosslinkers which have as functional group at least one halohydrin, glycidyl, aziridine, isocyanate unit or a halogen atom are suitable. Examples thereof include epichlorohydrin or bischlorohydrin ethers of polyalkylene glycols having 2 to 100 ethylene oxide and / or propylene oxide units and the compounds listed in DE-A 19 93 17 20 and US Pat. No. 4,144,123. Methods for the preparation of crosslinked polyethyleneimines are i.a. from the o.g. Fonts and EP-A 895 521 and EP-A 25 515 known.

Furthermore, grafted polyethyleneimines are suitable, it being possible for all compounds which can react with the amino or imino groups of the polyethyleneimines to be used as the grafting agent. Suitable grafting agents and processes for the preparation of grafted polyethyleneimines can be found, for example, in EP-A 675 914.

Likewise suitable polyethyleneimines are amidated polymers which are usually obtainable by reaction of polyethyleneimines with carboxylic acids, their esters or anhydrides, carboxamides or carboxylic acid halides. Depending on the proportion of amidated nitrogen atoms in the Polyethyleniminkette the amidated polymers can be subsequently crosslinked with said crosslinkers. In this case, up to 30% of the amino functions are preferably amidated, so that for a closing cross-linking reaction still enough primary and / or secondary nitrogen atoms are available.

Also suitable are alkoxylated polyethyleneimines, which are obtainable, for example, by reacting polyethyleneimine with ethylene oxide and / or propylene oxide. Such aloxylated polymers are also crosslinkable.

Other suitable polyethyleneimines include hydroxyl-containing polyethyleneimines and amphoteric polyethyleneimines (incorporation of anionic groups) and lipophilic polyethyleneimines, which are generally obtained by incorporation of long-chain hydrocarbon radicals into the polymer chain. Methods for the preparation of such polyethyleneimines are known to the person skilled in the art, so that no further details are required.

Accordingly, the polyethyleneimines 10d) are preferably selected from

Homopolymers of ethyleneimine,

Copolymers of ethyleneimine and amines having at least two amino groups, crosslinked polyethyleneimines, - grafted polyethyleneimines, amidated polymers obtainable by reaction of polyethyleneimines with

Carboxylic acids or carboxylic acid esters, anhydrides, amides or halides, alkoxylated polyethyleneimines, hydroxyl-containing polyethyleneimines, amphoteric polyethyleneimines, and lipophilic polyethyleneimines.

Suitable polyethyleneimines usually have a weight-average molecular weight of from 100 to 3,000,000, preferably from 200 to 1,000,000 and more preferably from 500 to 500,000 g / mol, determined by means of light scattering or gel permeation chromatography (GPC).

The polyethylenimines 10d) can be used as such ("anhydrous") or as a solution or suspension, with water being the preferred solvent.The viscosity of the "anhydrous" polyethyleneimines - their water content in accordance with DIN 53715 according to Karl Fischer is a maximum of ca. 1 wt .-% - is generally in the range of 100 to> 200,000 mPa · s, preferably in the range of 500 to> 200,000 mPa ^« s, determined according to DIN EN ISO 2555 (Brookfield RVT, 20 ⁰ C, spindle 6, 20 rpm).

Suitable aqueous solutions of polyethyleneimines generally have a water content (according to DIN 53715 according to Karl Fischer) of 20 to 99, preferably 40 to 80 Wt .-% on; the viscosity of these solutions according to DIN EN ISO 2555 (Brookfield RVT, 20 C ₁ ⁰ 5 spindle, 20 rpm) is usually 50 to 100,000, preferably 200 to 50,000 mPa ^«s.

It is preferable to use polyethyleneimines having a water content of at most 5% by weight, e.g. about 0.5 to 1 wt .-%, according to DIN 53715 after Karl Fischer.

In a preferred embodiment, the polyethyleneimines are hyperbranched or hyperbranched. Highly hyperbranched or hyperbranched polyethyleneimines in the context of this invention are understood as meaning unvarnished macromolecules having -NH groups which are structurally as well as molecularly nonuniform. They can be constructed either from a central molecule analogous to dendrimers, but with uneven chain length of the branches. However, they can also be constructed linearly with functional side groups or, as a combination of the two extremes, have linear and branched molecular moieties. For the definition of dendrimeric and hyperbranched polymers see also PJ. Flory, J. Am. Chem. Soc. 1952, 74, 2718 and H. Frey et al., Chem. Eur. J. 2000, 6, no. 14, 2499.

The degree of branching (DB) is defined as

T + Z

L-ZLJ

T + Z + L

where T is the number of terminal monomer units, Z is the number of branched monomer units, and L is the number of linear monomer units. These numbers can be determined by ¹³ C nuclear magnetic resonance spectra as primary (gives T), tertiary (gives Z) and secondary (gives L) amino groups. In the context of the present invention, "dendrimer" is understood to mean that the degree of branching is 99.9 to 100% For the definition of the degree of branching, see also H. Frey et al., Acta Polym., 1997, 48, 30.

The degree of branching of the inventively preferred highly branched or hyperbranched polyethyleneimines is generally 40 to 100, preferably 50 to 80 and in particular 55 to 70%.

Suitable polyethyleneimines are also commercially available, for example as Lupasol® from BASF. In particular Lupasol® WF, anhydrous (water content of at most 1% by weight, according to DIN 53715 according to Karl Fischer), highly branched polyethyleneimine having a weight-average molecular weight of about 25,000 g / mol determined by means of GPC, a viscosity of> 200,000 mPa ^' S (Brookfield RVT, 2O ⁰ C, spindle 6, 20 rpm) and a dynamic viscosity of about 15,000 mPa * s (ISO 2555, 50 ⁰ C), is well suited. A process for the preparation of said formaldehyde scavengers 10a) to 10d) are known to the person skilled in the art or the compounds are commercially available, which is why further details are unnecessary. One or more different formaldehyde scavengers 10) can be used.

11)

Antioxidants, if used in amounts of from 0.01 to 3, preferably 0.05 to 2 and in particular 0.1 to 1 wt .-%, based on the finished POM. Suitable antioxidants 11) are listed below under 11 a), 11 b) and 11 c).

11a)

Stabilizers against thermo-oxidative degradation of POM, in particular all compounds with phenolic structure, which have at least one sterically demanding group on the phenolic ring. Preferably, e.g. Compounds of the formula

into consideration, in which mean:

R ¹ and R ^{2 are} an alkyl group, a substituted alkyl group or a substituted TYi azolgruppe, wherein 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 Pat. No. 4,360,617).

Another group of preferred sterically hindered phenols IV) is derived from substituted benzenecarboxylic acids, in particular substituted benzenepropionic acids.

Particularly preferred compounds of this class are compounds of the formula

wherein R ⁴ , R ⁵ , R ⁷ and R ⁸ independently of one another Ci-C ₈ alkyl groups, which in turn may be substituted (at least one of which is a sterically demanding group) and R ^{6 is} a bivalent aliphatic radical having 1 to 10 carbon atoms which may also have CO bonds in the main chain.

Preferred compounds corresponding to this formula are

commercially available as Irganox® 245 from Ciba-Geigy, and

a commercial product Irganox® 259 from Ciba-Geigy.

Further examples of suitable antioxidants 11a) are:

4,4'-Butyiiden-bis (6-tert-butyl-3-methyl-phenol),

2,2'-methylenebis (4-methyl-6-tert-butyl-phenol), N, N'-hexamethylene-bis (3,5-di-tert-butyl-4-hydroxyhydrozinnamide),

1,6-hexamethylene bis (3,5-di-tert-butyl-4-hydroxyhydrozinnamate),

N _l N'-bis (3,5-di-tert-butyl-4-hydroxyhydrozinnamoyl) hydrazine,

Tetrakis-methylene (3,5-di-tert-butyl-4-hydroxyhydrozinnamate) methane, i.δ-CS.e-oxa-octamethylene-1 to CS-methyl-S-tert-butyl-hydroxyhydrozinnamate), 1, 6 hexanediol-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate],

Pentaerythril-tetrakis- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate],

DistiaryI-3,5-di-tert-butyl-4-hydroxybenzylphosphonate,

2,6,7-trioxa-1-phosphabicyclo [2.2.2] oct-4-ylmethyl-3,5-di-tert-butyl-4-hydroxyhydrocinnamate, SS-di-tert-butyl ^ hydroxyphenyl-S.δ distearyl thiotriazylamin,

2- (2'-Hydroxy-3 ¹ -hydroxy-3 ', 5 ^I -di-tert-butylphenyl) -5-chlorobenzotriazole, 2,6-di-tert-butyl-4-hydroxymethylphenol,

I .SS-trimethyl ^^. Θ-tris-CS.δ-di-tert-butyl ^ -hydroxybenzyO-benzene, 4,4'-methylenebis (2,6-di-tert-butylphenol) _I 3,5-di-tert-butyl-4-hydroxybenzyl-dimethylamine, and N.N'-hexamethylene-bisCS.δ-di-tert-butyl-hydroxyhydrocinnamide).

Have proven to be particularly effective and therefore preferably be used

2,2 ¹ -methylene bis (4-methyl-6-tert-butylphenyl) ₁

1,6-hexanediol bis (3,5-di-tert-butyl-4-hydroxyphenyl) propionate (Irganox® 259), pentaerythrityl tetrakis [3- (3,5-di-tert-butyl 4-hydroxyphenyl) -propionate] and the above-described Irganox® 245 from Ciba Geigy, which is particularly well suited.

In some cases, sterically hindered phenols having no more than one sterically hindered group ortho to the phenolic hydroxy group have been found to be particularly advantageous; in particular for improving the color stability when stored in diffuse light for extended periods of time.

Also useful as antioxidants 11a) are sulfur-containing compounds.

11b)

Stabilizers against photo-oxidative degradation of POM, which act as UV absorbers, for example

i) Benzophenone derivatives such as

2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone,

2-hydroxy-4-alkoxybenzophenones with n-octyl, iso-octyl and dodecyl as the alkyl group,

2,2'-dihydroxy-4-methoxybenzophenone,

2,2'-dihydroxy-4,4'-dimethoxybenzophenone,

2-hydroxy-4-methoxy-5-sulphobenzophenone and 2-hydroxy-4-oxybenzylbenzophenone,

ii) Benzotriazole derivatives, such as those available under the name Tinuvin® from Ciba Geigy, for example

2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-5'-tert-octylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5 ^I -di-tert. -amyl-phenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di- {2 "-phenyl} iso-propyl-phenyl) benzotriazole _l 2- (2 ^L -hydroxy-3' ₁ 5'-di-tert-butyl phenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3'-methyl-5'-tert-butyl-phenyl) -5-chlorobenzotriazole, 2- (2-hydroxy-5-methylphenyl) -benzotriazole, 2- (2-Hydroxy-3,5-di-tert-butylphenyl) -benzotriazole, 2- (3,5-di-tert-amyl-hydroxyphenyl) -benzotriazole, 2- (2-hydroxy-3 ', 5'-diisoamylphenyl) - benzotriazole, 2- (2'-hydroxy-4-octoxyphenyl) benzotriazole, 2- (2H) -benzotriazol-2-yl) -4,6-bis- (1,1-dimethylpropyl) -phenol and 2- (2H- Benzotriazol-2-yl) -4- (1, 1-dimethylpropyl) -6- (1-methylpropyl) -phenol, with 2- (2Η-hydroxy-3'5'-bis (1,1-dimethylbenzyl) phenyl) benzotriazole particularly is preferred.

iii) 2-ethylhexyl-2-cyano-3,3'-diphenylacrylate,

iv) benzoates such as

p-tert-butylphenylsalicylate, p-octylphenylsalicilate, n-hexadecyl-3,5-di-tertiary-butyl-4-hydroxybenzoate,

v) oxanilides, such as N- (2-ethylphenyI) -N '- (2-ethoxy-5-tertiary butylphenyl) oxalamide, or 2-ethyl-2'-ethoxyoxanilide,

vi) UV-absorbing pigments, especially carbon black, but also TiO 2 also act to stabilize the action of light, with sufficient dosage even in the presence of colored pigments.

11c) stabilizers against photo-oxidative degradation of POM, which are hindered amine light stabilizers (HALS). Suitable HALS are in particular compounds of the formula

into consideration, where

R is identical or different alkyl radicals R ^{1 are} hydrogen or an alkyl radical and A represents an optionally substituted 2- or 3-membered alkylene chain.

Preferred HALS are derivatives of 2,2,6,6-tetramethylpiperidine such as

4-acetoxy-2,2,6,6-tetramethylpiperidine, 4-stearoyloxy-2,2,6,6-tetramethylpiperidine, 4-aryloxy-2 ₁ 2 _I 6,6-tetramethylpiperidine ₁ 4-methoxy-2,2 ₁ 6,6-tetramethylpiperidine, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine ₁ 4-Cyclohexyloxy-2 ₍ 2 _> 6,6-tetramethylpiperidine, 4-phenoxy-2,2,6,6,6-tetramethylpiperidine ₎ ^ Benzoxy - ^^. Θ.δ-tetramethylpiperidine, and 4- (phenylcarbamoyloxy) -2,2,6,6-tetramethylpiperidine.

Further suitable are:

Bis (2 ₎ 2,6,6-tetramethyl-4-piperidyl) oxalate,

Bis (2,2,6,6-tetramethyl-4-piperidyl) succinate ₁

Bis (2,2,6,6-tetramethyl-4-piperidyl) maIonat, bis (2,2,6-tetramethyl _I 6 - ^ - piperidyl) adipate

Bis (1, 2,2,6,6-pentamethylpiperidyl) sebacate,

Bis (2,2 _l, 6,6-tetramethyl-4-piperidyl) terephthalate,

1, 2-bis (2 _l 2 _I 6,6-tetramethyl-4-piperidyloxy) ethane,

Bis (2 _I 2 _> 6,6-tetramethyl-4-piperidyl) hexamethylene-1,6-dicarbamate, bis-O-methyl-1-yl-tetramethyl-1-diperidoxyadipate, and

Tris (2 ₎ 2 _{l of} 6,6-tetramethyl-4-piperidyl) benzene-1,3,5-tricarboxylate.

Preference is furthermore given to relatively high molecular weight piperidine derivatives, for example the polymer of dimethyl butanedioate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol or poly-6- (1,1,3,3-tetramethylbutyl) amino-1, 3,5-triazine-2 _I 4-diyl (2,2 ₎ -6,6-tetramethyl-4-piperidinyl) imino-1,6-hexanediyl (2 _I 2 _J 6,6-tetramethyl-14-piperidinyl) imino, and polycondensates of dimethyl succinate and 1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine which are like bis (2,2,6,6-tetramethyl-4-piperidyl) sebazate are particularly well suited.

Such compounds are commercially available under the name Tinuvin® or Chimasorb® from Ciba-Geigy.

Another particularly preferred HALS antioxidant 11c) is called Uvinul® 4049 H from BASF:

Further details and other, also suitable antioxidants are Gächter / Müller (ed.), Plastics Additives, 4th Edition 1993, reprint Nov. 1996, Hanser Verlag Munich, on pages 40 to 48 and 205 to 213 refer, and Bottenbruch ( Ed.), Kunststoff-Handbuch, Volume 3/1 Polycarbonates Polyacetals Polyester Cellulose esters, Hanser-Verlag Munich 1993, on pages 320 to 323.

A process for the preparation of said antioxidants are known in the art or the compounds are commercially available, which is why further details are unnecessary. One or more different antioxidants 11) can be used.

Process product and use of the process in POM production

A degassed, low-monomer POM is obtained as the product of the process according to the invention for residual monomer removal (in the following "degassing process") .The residual monomer content of the POM is generally from 0.0001 to 0.02% by weight, in particular from 0.0001 to 0.01 Wt .-% and particularly preferably 0.0001 to 0.001 wt .-%.

The degassing process according to the invention makes it possible to degas polyoxymethylenes in a particularly gentle manner and to provide them with additives. The obtained POM is characterized not only by a low residual monomer content, but also by a low intrinsic color and good mechanical properties.

Another object of the invention is the use of the above-described degassing during or after the preparation of polyoxymethylene Homo- or copolymers.

In the production of POM, suitable monomers are usually first prepared in a so-called monomer system, for example trioxane from aqueous formaldehyde solution, and / or suitable monomers are stored. Thereafter, the monomers are transferred from the monomer plant in a polymerization reactor and polymerized there to POM, as already described above. The described crude POM from which the unreacted residual monomers are reacted with the erfindungsge- According degas degassing be separated. Likewise, it is possible to separate off residual monomers by the degassing process according to the invention already during the polymerization to give the POM, or else this residual monomer separation according to the invention is carried out both during and after the polymerization.

Another subject of the invention is therefore also a method (hereinafter "POM method") for the preparation of Polyoxymethylenhomo- or copolymers, characterized in that first prepared or stored in a monomer monomer suitable monomers, then polymerizing the monomers in a polymerization reactor to said polymers , and during or after this polymerization, the residual monomers contained in the polymers are removed by the above degassing process. Of course, the residual monomers can also be removed during and after the polymerization.

The POM process according to the invention accordingly comprises the degasification process according to the invention as a process step.

It is also preferred to minimize the residence time between the individual steps of the POM process. For example, one can minimize the residence time between the polymerisation reactor or demolition zone and the degassing device, and / or minimize the residence time between the mixing device and the granulator.

As mentioned, the residual monomers removed by the degassing process can be used again as feedstocks in POM production, ie recycled (recycled) in the POM process according to the invention. You can adjust the destination of this return of the production plant. For example, one can return the residual monomers directly into the polymerization reactor or in its feed, or return them to the monomer plant.

Consequently, the POM process is preferably characterized in that the removed residual monomers are recycled to the polymerization reactor or to the monomer unit. Of course you can also combine these two variants.

Finally, the subject of the invention is also the polyoxymethylene homo- or copolymers obtainable by the described POM process. example

A monomer mixture consisting of 95% by weight of trioxane, 3% by weight of dioxolane and 0.005% by weight of methylal was continuously metered into a polymerization reactor at a flow rate of 5 kg / h. The reactor was a tubular reactor equipped with static mixers and operated at 155 ^° C. and 30 bar.

As an initiator, 0.1 ppmw of perchloric acid was mixed into the monomer stream, using a 0.01% by weight solution of 70% by weight aqueous perchloric acid in gamma-butyrolactone. After a polymerization time (residence time) of 2 minutes, triacetonediamine (as a 0.1% by weight solution in 1,3-dioxolane) was metered into the polymer melt as deactivator and mixed in so that the deactivator was present in 10-fold molar excess to the initiator , The residence time in the deactivation zone was 3 min.

The polymer melt was withdrawn through a pipeline and expanded via a control valve in a first degassing, which was provided with an exhaust pipe. The temperature of the Entgasungstopfs was 190 ⁰ C and the pressure was 3 bar.

From the first pot, the melt was withdrawn through a pipe and expanded via a control valve in a second Entgasungstopf, which was provided with an exhaust pipe. The temperature of the degassing pot was 190 ° C and the pressure was ambient pressure. The pot had no bottom and was mounted directly on the feed dome of a twin-screw extruder ZSK 30 from Werner & Pfleiderer, so that the degassed polymer fell from the pot directly onto the extruder screws.

The extruder was operated at 19O ⁰ C and with a screw speed of 150 rpm and was provided with vent openings, which were operated at 500 mbar. In addition, it had a feed opening for additives, by which 0.5 kg / h of the antioxidant Irganox® 245 (formula see under 11a) above) were added by Ciba. The product was discharged in a conventional manner, cooled and granulated.

Claims

claims

1. A process for the removal of unreacted residual monomers from polyoxymethylene Homo- or copolymers (POM) by degassing in a degassing device and subsequent mixing in a mixing apparatus, characterized in that the residence time of the POM between the discharge from the degassing and Entry into the mixing device is a maximum of 60 sec.

2. The method according to claim 1, characterized in that the residence time is a maximum of 30 sec.

3. Process according to claims 1 to 2, characterized in that the degassing device is a degassing pot.

4. Process according to claims 1 to 3, characterized in that the mixing device is an extruder.

5. The method according to claims 1 to 4, characterized in that the output of the degassing device coincides with the entry of the mixing device.

6. Process according to claims 1 to 5, characterized in that the degassing pot is arranged on the extruder and empties directly into the extruder.

7. Process according to claims 1 to 6, characterized in that the residual monomers are selected from trioxane, formaldehyde, tetroxane, 1, 3-dioxolane, 1, 3-dioxepane, ethylene oxide and oligomers of formaldehyde.

8. Process according to claims 1 to 7, characterized in that in the mixing device the POM is mixed with customary additives.

9. Process according to claims 1 to 8, characterized in that a further degassing takes place in the mixing device.

10. Use of the method according to claims 1 to 9 during or after the preparation of Polyoxymethylenhomo- or copolymers.

11. A process for the preparation of polyoxymethylene homopolymers or copolymers, which comprises first preparing or storing suitable monomers in a monomer system, then dissolving the monomers in a polymerizate. polymerized onsreaktor to said polymers, and during or after this polymerization, the residual monomers contained in the polymers by the method according to claims 1 to 9 removed.

12. The method according to claim 11, characterized in that the removed

Residual monomers are recycled into the polymerization reactor or into the monomer.

13. polyoxymethylene homo- or copolymers, obtainable by the process according to claims 11 to 12.