Method for deactivating acid catalysts during the production process of polyoxymethylene copolymers

Abstract

The present invention relates to a method for deactivating an acid catalyst during a production process of a polyoxymethylene copolymer (cPOM) by adding (A) triisopropanolamine (tris(2-hydroxypropyl)amine) and / or (B) sodium carbonate and / or sodium bicarbonate, preferably (A) triisopropanolamine (tris(2-hydroxypropyl)amine) and (B) sodium carbonate and / or sodium bicarbonate, to a mixture (M1) comprising the polyoxymethylene copolymer (cPOM) and the acid catalyst.

Description

[Technical Field]

[0001] The present invention relates to a method for deactivating an acid catalyst during a production process of a polyoxymethylene copolymer (cPOM) by adding (A) triisopropanolamine (tris(2-hydroxypropyl)amine) and / or (B) sodium carbonate and / or sodium bicarbonate, preferably (A) triisopropanolamine (tris(2-hydroxypropyl)amine) and (B) sodium carbonate and / or sodium bicarbonate, to a mixture (M1) comprising the polyoxymethylene copolymer (cPOM) and the acid catalyst.

[0002] Furthermore, the present invention relates to the use of (A) triisopropanolamine and (B) sodium carbonate and / or sodium bicarbonate to deactivate an acid catalyst during the production of polyoxymethylene copolymers (cPOM).

[0003] Furthermore, the present invention relates to a method for producing a polymer molding composition (PM) comprising a polyoxymethylene copolymer (cPOM), to the polymer molding composition (PM) obtainable by this production method, and to the use of the polymer molding composition (PM) for the production of molded articles.

[0004] Polyoxymethylene copolymers have long been known. These polymers have many excellent properties, making them suitable for a wide variety of industrial applications. Polyoxymethylene copolymers are engineering thermoplastics used in a variety of applications in the transportation, electrical equipment, electronics, and consumer goods industries. Polyoxymethylene copolymers are also known as acetal resins, polyacetals, and polyformaldehyde. To produce polyoxymethylene copolymers, formaldehyde is generally converted to its cyclic oligomer, preferably 1,3,5-trioxane. Polyoxymethylene copolymers can be obtained by polymerizing a cyclic oligomer of formaldehyde, preferably 1,3,5-trioxane, with a comonomer in the presence of an acid catalyst. The polymerization can be carried out, for example, as a bulk polymerization in a melt kneader. After the polymerization reaction, a crude polyoxymethylene copolymer is obtained, still containing the acid catalyst. If the acid catalyst remains in the polyoxymethylene copolymer, it may catalyze the depolymerization reaction of the polyoxymethylene copolymer to formaldehyde, thereby resulting in an unstable polyoxymethylene copolymer with poor properties.

[0005] Therefore, after polymerization, the acid catalyst is typically deactivated and the crude polyoxymethylene copolymer is typically further stabilized by removal of residual monomers and removal of unstable end groups to obtain the final polyoxymethylene copolymer.

[0006] In order to deactivate the acid catalyst contained in the crude polyoxymethylene copolymer, a deactivator is usually added to the crude polyoxymethylene copolymer. A basic compound is generally used as the deactivator. When the acid catalyst used is a Bronsted acid such as perfluorinated acid or trifluoromethanesulfonic acid, the basic compound generally neutralizes the acid. On the other hand, when the acid used is a Lewis acid such as a BF3 derivative, an acid-base product in the form of an adduct or salt is formed, i.e., a complex between the acid catalyst and the basic compound, which remains in the polymer matrix of the polyoxymethylene copolymer.

[0007] DE-A-3703790 discloses a method for producing polyoxymethylene copolymers in which the acid catalyst is deactivated with triethylamine, triethanolamine, or tri-n-butylamine.

[0008] EP 1 688 461 also discloses a method for producing polyoxymethylene copolymers in which the acid catalyst is deactivated by the addition of an amine, namely triethylamine.

[0009] EP 0 244 245 A1 discloses a method for producing polyoxymethylene copolymers in which a hindered heterocyclic amine is used to deactivate the acid catalyst.

[0010] DE 19633708 A1 discloses a method for producing polyoxymethylene copolymers in which the acid catalyst is deactivated with ammonia, trimethylamine, dimethylamine, or triethylamine.

[0011] US Pat. No. 7,893,140 discloses a method for producing polyoxymethylene copolymers in which an acid catalyst is deactivated with triethylamine, tributylamine, triethanolamine, or tributanolamine.

[0012] WO 93 / 22359 discloses a method for producing polyoxymethylene copolymers by copolymerizing trioxane as the main monomer and a cyclic ether or cyclic formal as a comonomer using a cationically active catalyst, in which an alkali metal fluoride is contacted with the copolymer after completion of the copolymerization, thereby deactivating the polymerization catalyst.

[0013] WO 2020 / 011873 discloses a method for deactivating an acid catalyst during a polyoxymethylene copolymer (cPOM) manufacturing process by adding triisopropanolamine to a mixture containing the polyoxymethylene copolymer (cPOM) and the acid catalyst.

[0014] However, the methods and quenchers used in the prior art for producing polyoxymethylene copolymers sometimes result in polyoxymethylene copolymers with insufficient thermal and hydrolytic stability. Furthermore, in some cases, polyoxymethylene copolymers obtained by the methods described in the prior art exhibit excessively high formaldehyde emissions, making the final polyoxymethylene copolymers unusable for food or drinking water applications. Furthermore, in some cases, polyoxymethylene copolymers obtained by the methods described in the prior art exhibit migration of the quencher, making these polyoxymethylene copolymers also unusable for food contact or drinking water applications. Furthermore, in some cases, polyoxymethylene copolymers obtained by the methods described in the prior art exhibit poor stability when colored with common color masterbatches.

[0015] Therefore, the underlying object of the present invention is to provide a method for deactivating an acid catalyst during the production process of a polyoxymethylene copolymer, which results in a polyoxymethylene copolymer that does not have any of the above-mentioned disadvantages of the prior art, or has them to a significantly reduced extent. In particular, it is desirable that this method results in a polyoxymethylene copolymer that exhibits improved thermal and hydrolytic stability, lower formaldehyde emissions, and good color values, as well as good mechanical properties, and at the same time is suitable for food contact or drinking water applications.

[0016] The object is to provide a method for deactivating an acid catalyst during a process for producing polyoxymethylene copolymer (cPOM), the method comprising: a) providing a first mixture (M1) comprising a polyoxymethylene copolymer (cPOM) and an acid catalyst; b) (A) triisopropanolamine and / or (B) Sodium carbonate and / or sodium bicarbonate is added to the first mixture (M1) to deactivate the acid catalyst, Polyoxymethylene copolymer (cPOM), and a complex of an acid catalyst with component (A), and / or Reaction product of the acid catalyst and component (B) Obtaining a second mixture (M2) comprising: c) optionally adding at least one additive to the second mixture (M2); d) treating the second mixture (M2) under vacuum at a temperature in the range of 180-280°C to obtain a third mixture (M3); The problem is solved by a method including:

[0017] Another subject of the invention is a polymeric molding composition (PM) obtainable by the method according to claim 12.

[0018] It has been surprisingly found that when triisopropanolamine (component (A)) and sodium carbonate (NaCO) and / or sodium bicarbonate (NaHCO) (component (B)) are used to deactivate the acid catalyst in a process for producing polyoxymethylene copolymer (cPOM), the properties of the polyoxymethylene copolymer (cPOM) are improved. The polyoxymethylene copolymer (cPOM) exhibits improved thermal and hydrolytic stability, lower formaldehyde emissions, good color values, and good mechanical properties.

[0019] Furthermore, it has surprisingly been found that the complex of the acid catalyst with component (A) and / or the reaction product of the acid catalyst with component (B) remaining in the finished polyoxymethylene copolymer (cPOM) is stable, and therefore the final polyoxymethylene copolymer (cPOM) is thermally stable, hydrolytically stable, exhibits low formaldehyde emissions and low quencher migration, and is therefore particularly suitable for applications requiring contact with food or drinking water.

[0020] Step a) First mixture (M1) In step a), a first mixture (M1) is provided which comprises a polyoxymethylene copolymer (cPOM) and an acid catalyst.

[0021] Polyoxymethylene copolymers (cPOM) are known per se and are preferably prepared by polymerizing trioxane (as a monomer) with one or more comonomers.

[0022] Generally, the polyoxymethylene copolymer (cPOM) contained in the first mixture (M1) comprises 60 to 99.99 mol % of -CHO- repeat units and 0.01 to 40 mol % of repeat units according to formula (I). [ka] [In the formula, R 1 ~R4 are each independently a hydrogen atom, a C1-C4 alkyl group, or an alkoxy-substituted alkyl group having 1 to 4 carbon atoms, and R 5 is a chemical bond, -CH2-, -OCH2-, a C1-C4 alkyl or C1-C4 alkoxy substituted methylene group, or the corresponding oxymethylene group, and n is 0-3, and the mol % of -CHO- repeat units and the mol % of repeat units according to formula (I) are based on the total number of moles of repeat units contained in the polyoxymethylene copolymer (cPOM).

[0023] Preferably, the polyoxymethylene copolymer (cPOM) comprises 60 to 99.99 mol%, more preferably 80 to 99.95 mol%, even more preferably 90 to 99.9 mol%, and particularly preferably 94 to 99.5 mol% of -CHO- repeat units. Preferably, the polyoxymethylene copolymer (cPOM) comprises 0.01 to 40 mol%, more preferably 0.05 to 20 mol%, even more preferably 0.1 to 10 mol%, and particularly preferably 0.5 to 6 mol% of repeat units according to formula (I), the mol% in each case being based on the total number of moles of repeat units contained in the polyoxymethylene copolymer (cPOM).

[0024] Another subject of the present invention is therefore a method, wherein the polyoxymethylene copolymer (cPOM) comprises 60 to 99.99 mol % of -CHO- repeating units and 0.01 to 40 mol % of repeating units according to formula (I). [ka] [In the formula, R 1 ~R 4 are each independently a hydrogen atom, a C1-C4 alkyl group, or an alkoxy-substituted alkyl group having 1 to 4 carbon atoms, and R 5 is a chemical bond, —CH—, —OCH—, a C1-C4 alkyl or C1-C4 alkoxy substituted methylene group, or the corresponding oxymethylene group, and n is 0-3.

[0025] The -CHO- repeat unit is generally introduced into polyoxymethylene copolymers (cPOM) by polymerizing at least one main monomer selected from the group of cyclic formals (cyclic oligomers of formaldehyde), with 1,3,5-trioxane being particularly preferred.

[0026] The repeat units according to formula (I) can be advantageously introduced into the polyoxymethylene copolymer (cPOM) by ring-opening polymerization of at least one first comonomer selected from the group of those of formula (II): [ka] [In the formula, R 1 ~R 5 and n is as defined above for formula (I).

[0027] Preferably, the at least one first comonomer is selected from the group consisting of ethylene oxide, 1,2-propylene oxide, 1,2-butylene oxide, 1,3-butylene oxide, 1,3-dioxane, 1,3-dioxolane, and 1,3-dioxepane, with 1,3-dioxolane being particularly preferred.

[0028] Optionally, the polyoxymethylene copolymer (cPOM) may comprise repeat units derived from at least one second comonomer, preferably selected from the group consisting of cyclic ethers of formula (III) or acetals of formula (IV). [ka] wherein Z is a chemical bond, -O-, -ORO- (wherein R is C1-C8 alkylene or C3-C8 cycloalkylene), linear oligoformal, and polyformal. Preferred second comonomers are selected from the group consisting of ethylene diglycidyl, diglycidyl ethers, and diethers derived from a 2:1 molar ratio of glycidyl to formaldehyde, dioxane, or trioxane, and diethers derived from 2 moles of a glycidyl compound and 1 mole 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, 1,3-propanediol, and cyclohexane-1,4-diol.

[0029] When at least one second monomer is used, the at least one second monomer is preferably used in an amount such that the repeat units derived therefrom are contained in the polyoxymethylene copolymer (cPOM) in an amount of 0.001 to 5%, preferably 0.01 to 2%, the mol % in each case being based on the total number of moles of repeat units contained in the polyoxymethylene copolymer (cPOM).

[0030] The molecular weight of the cPOM can be adjusted to the required melt viscosity of the resulting product by using at least one chain transfer agent (CTA). The CTA can be a linear oligoformal such as dimethoxymethane, diethoxymethane, or dibutoxymethane. Dimethoxymethane (CH3OCH2OCH3) is the preferred CTA.

[0031] The melting point of the polyoxymethylene copolymer (cPOM) contained in the first mixture (M1) is preferably in the range of 150 to 200° C., more preferably in the range of 160 to 180° C. The melting point of the cPOM is determined in accordance with DIN EN ISO 11357-3 (2013-04) at a heating and cooling rate of 20 K / min and a sample weight of approximately 8.5 mg.

[0032] The molecular weight (weight average M w; determined as below) can be adjusted within a wide range. w is preferably in the range of 10,000 to 240,000 g / mol±10%, while the number average molecular weight M n (determined as described below) is preferably in the range of 8000 to 85000 g / mol. Preferably, the polyoxymethylene copolymer (cPOM) contained in the first mixture (M1) has a molecular weight (M w ), while its molecular weight (M n ) is preferably in the range of 9000 to 38000 g / mol. The M of the polyoxymethylene copolymer (cPOM) contained in the first mixture (M1) w / M n The ratio (polydispersity index) is preferably in the range of 1.4 to 14, and more preferably, M w / M n is in the range of 2.1 to 14.

[0033] The molecular weights of the polymer and cPOM were determined by size exclusion chromatography (SIZE EXTRACTION CHROMATOGRAPHY) in an SEC system. The SEC system consisted of the following combination of separation columns: a pre-column 5 cm long and 8 mm in diameter, and a second linear column 30 cm long and 7.5 mm in diameter. The separation material in both columns was PL-HFIP gel from Polymer Laboratories. The detector used was an Agilent 1100 differential refractometer. A mixture of hexafluoroisopropanol and 0.05% potassium trifluoroacetate was used as the eluent. The flow rate was 1 ml / min, and the column temperature was 35°C. 60 microliters of a solution with a concentration of 1.5 g of sample per liter of eluent was injected. The sample solution was previously filtered through a Millipore Millex FG (pore width 0.2 micrometers). Narrow-dispersion PMMA standards from PSS (Polymer Standards Service GmbH, Mainz, DE) with molecular weights M ranging from 800 to 2,220,000 g / mol were used for calibration. The polydispersity index is defined as the weight-average molecular weight divided by the number-average molecular weight.

[0034] The molecular weight distribution of the polyoxymethylene copolymer (cPOM) contained in the first mixture (M1) may be unimodal or essentially unimodal. It may also have a multimodal molecular weight distribution. It may be possible for the cPOM to have a bimodal molecular weight distribution.

[0035] In step a), a first mixture (M1) is provided, comprising a polyoxymethylene copolymer (cPOM) and an acid catalyst. The term "acid catalyst" in the present invention is understood to mean both exactly one acid catalyst and a mixture of two or more acid catalysts. Preferably, the first mixture (M1) comprises one acid catalyst. Furthermore, the term "acid catalyst" in the present invention is understood to include not only the acid catalyst itself, but also the catalytically active conversion product of the acid catalyst.

[0036] The acid catalyst may preferably be at least one, for example two, more preferably one halide of boron, tin, titanium, phosphorus, antimony, or arsenic.Therefore, it may be preferable that the halide is chloride or fluoride, or that the halide contains both.Examples thereof are boron trifluoride, tin tetrachloride, titanium tetrachloride, phosphorus pentafluoride, phosphorus pentachloride, antimony pentafluoride, and arsenic pentafluoride, and in particular their complex compounds.

[0037] The acid catalyst may preferably be at least one halide of boron, in particular boron trifluoride, e.g., boron trifluorohydrate, or at least one, more preferably one coordination compound of a boron halide with at least one, more preferably one organic compound containing at least one oxygen atom. The organic compound for forming the coordination compound of the boron halide may be, for example, an alcohol or an ether.

[0038] Preferably, the acid catalyst is selected from the group consisting of boron halides coordinated with ethers, and in particular, alkyl ethers such as C1-C4 alkyl ethers may be most preferred. Coordination compounds of boron trifluoride with ethers, particularly dialkyl ethers such as C1-C4 dialkyl ethers, may be most preferred, particularly boron trifluoride dibutyl etherate, boron trifluoride diethyl etherate, boron trifluoride dimethyl etherate, or mixtures thereof. Most preferably, boron trifluoride diethyl etherate can be used.

[0039] Therefore, another subject of the present invention is a process, wherein the acid catalyst is at least one acid catalyst selected from the group consisting of boron trifluoride, coordination complexes of boron trifluoride with water, coordination complexes of boron trifluoride with dialkyl ethers, and catalytically active conversion products of the aforementioned acid catalysts.

[0040] In a particularly preferred embodiment, the first mixture (M1) comprises boron trifluoride diethyl etherate and a catalytically active conversion product of boron trifluoride diethyl etherate as the acid catalyst.

[0041] The amount of acid catalyst in the first mixture (M1) is not particularly limited. Typically, the amount of acid catalyst in the first mixture (M1) is 10 to 150 ppm, preferably 20 to 140 ppm, more preferably 30 to 130 ppm, and particularly preferably 40 to 100 ppm, in each case based on the total weight of the main monomer and comonomer, preferably based on the total weight of the first mixture (M1). If the amount is smaller, the reaction may start slower, and if the amount is larger, the reaction usually does not proceed faster.

[0042] Another subject of the present invention is therefore a process, wherein the acid catalyst in step a) is present in an amount of 10 to 150 ppm, based on the total weight of the first mixture (M1).

[0043] In a preferred embodiment, providing the first mixture (M1) in step a) comprises step a1), i.e. polymerizing at least one main monomer selected from the group of cyclic formals, preferably 1,3,5-trioxane, and at least one first comonomer selected from the group of those of formula (II) and, optionally, at least one second comonomer in the presence of an acid catalyst.

[0044] Therefore, another subject of the present invention is a method for preparing ... medicament for use in a process comprising the steps of: a1) at least one main monomer selected from the group of cyclic formals and a monomer of formula (II) [ka] [In the formula, R 1 ~R 5 and n is as defined in formula (I). and optionally at least one second comonomer in the presence of an acid catalyst to provide a first mixture (M1) comprising a polyoxymethylene copolymer (cPOM) and an acid catalyst.

[0045] In step a1), the acid catalyst is preferably present in an amount of 10 to 150 ppm based on the total weight of the main monomer and comonomer.

[0046] Another subject of the present invention is therefore a process, wherein the acid catalyst in step a1) is present in an amount of 10 to 150 ppm, based on the total weight of the main monomer and the comonomer.

[0047] Generally, the polymerization in step a1) can be carried out using a variety of methods. Such methods are known to those skilled in the art or are available to those skilled in the art by applying their general knowledge. Preferably, the first mixture (M1) is produced by cationic polymerization. During cationic polymerization, the cPOM can be formed in bulk (i.e., without solvent or essentially without solvent).

[0048] The polymerization can be carried out at temperatures, pressures, and equipment generally known to those skilled in the art or available to those skilled in the art by applying their general knowledge. For example, the polymerization can be carried out in an extruder, such as a twin-screw extruder or a self-cleaning extruder, or a cascade of two or more extruders. It may also be possible to carry out the process disclosed herein in a kneader, such as a self-cleaning kneader, or a cascade of two or more kneaders. Generally, it may be advantageous to carry out the polymerization at a temperature as low as possible to avoid energy waste, yet at a temperature high enough to maintain polymerization and ensure good mixing, especially by maintaining at least one monomer and, if present, at least one comonomer in a liquid state. Therefore, it may be preferable to carry out the polymerization at a temperature of 50 to 150°C, whereby a temperature of 60 to 120°C may be more preferred. The temperature thus refers to the temperature in the mass.

[0049] In one embodiment, the first mixture (M1) may further comprise an unreacted residual monomer in an amount of 2 to 30 wt %, typically selected from the above-mentioned main monomers, comonomers, and formaldehyde.

[0050] In a preferred embodiment, the first mixture (M1) comprises, based on the total weight of the first mixture (M1): 70 to 98% by weight of polyoxymethylene copolymer (cPOM), 2 to 30 wt. % unreacted residual monomer, and 10 to 150 ppm acid catalyst Includes.

[0051] Step b) According to step b), (A) triisopropanolamine and / or (B) Sodium carbonate and / or sodium bicarbonate is added to the first mixture (M1) to deactivate the acid catalyst, Polyoxymethylene copolymer (cPOM), and a complex of an acid catalyst with component (A), and / or Reaction product of the acid catalyst and component (B) A second mixture (M2) is obtained containing:

[0052] In a preferred embodiment, according to step b), (A) Triisopropanolamine and (B) Sodium carbonate and / or sodium bicarbonate is added to the first mixture (M1) to deactivate the acid catalyst, Polyoxymethylene copolymer (cPOM), and a complex of an acid catalyst and component (A), and Reaction product of the acid catalyst and component (B) A second mixture (M2) is obtained containing:

[0053] In the present invention, the terms "component (A)" and "triisopropanolamine" are used interchangeably and therefore have the same meaning. The same applies to "component (B)" and sodium carbonate and / or sodium bicarbonate. These terms also have the same meaning and are likewise used interchangeably.

[0054] Triisopropanolamine (tris(2-hydroxypropyl)amine; TIPOA; component (A)) has a CAS number of 122-20-3. Its molar mass is 191.27 g / mol, its melting point is 45°C, and its boiling point is 301°C. Triisopropanolamine is water-soluble.

[0055] Sodium carbonate (Na2CO3; component (B)) has the CAS number 497-19-8. Its molar mass is 105.99 g / mol and its melting point is 851 °C. Sodium carbonate is water-soluble.

[0056] Sodium bicarbonate (NaHCO3; component (B)) has the CAS number 144-55-8. Its molar mass is 84.01 g / mol. Sodium bicarbonate is also water-soluble.

[0057] In step b), components (A) and (B) can be added simultaneously.

[0058] Another subject of the present invention is therefore a process, in which in step b) components (A) and (B) are added simultaneously.

[0059] However, it is also possible to add component (A) before component (B) in step b).

[0060] Another subject of the present invention is therefore a process, in which in step b) component (A) is added before component (B).

[0061] Another object of the present invention is a process, wherein in step b) component (A) is added before component (B), and component (B) is added simultaneously with at least one additive.

[0062] In this case, it will be clear to the skilled artisan that after step b) the second mixture (M2) Polyoxymethylene copolymer (cPOM) and Complex of acid catalyst and component (A) containing only and only after step c) the second mixture (M2) Reaction product of the acid catalyst and component (B) It is clear that this also includes

[0063] In step b), triisopropanolamine (component (A)) can be added in pure form, in the form of a slurry, or in the form of a solution containing triisopropanolamine and a solvent, which can be an organic solvent or water.

[0064] In one embodiment, the triisopropanolamine in step b) is added to the first mixture (M1) in the form of a solution containing triisopropanolamine and an organic solvent. Suitable organic solvents include, for example, cyclohexane, methanol, ethanol, acetone, methyl ethyl ketone, ethyl acetate, or benzene, with benzene and ethyl acetate being preferred. Ethyl acetate is most preferred.

[0065] When triisopropanolamine is added in the form of a solution, the concentration of triisopropanolamine is typically in the range of 1 to 50 wt %, preferably in the range of 2 to 40 wt %, more preferably in the range of 2 to 30 wt %, and particularly preferably in the range of 3 to 10 wt %, based on the total weight of the solution containing triisopropanolamine and the organic solvent.

[0066] In another embodiment, the triisopropanolamine in step b) is added to the first mixture (M1) in the form of a solution comprising triisopropanolamine and water.

[0067] However, ethyl acetate may be the most preferred solvent.

[0068] Furthermore, in another embodiment, triisopropanolamine may be added in step b) as a mixture with at least one other quenching agent selected from the group consisting of ammonia, triethylamine, tri-n-butylamine, and triethanolamine. However, in a preferred embodiment, triisopropanolamine is the only quenching agent added in step b).

[0069] In step b), triisopropanolamine is preferably added in a molar excess of 25:1 to 1:1, more preferably 10:1 to 1.1:1, particularly preferably 5:1 to 1.2:1, taking into account the acid catalyst contained in the first mixture (M1).

[0070] In step b), component (B) can be added in pure form, in the form of a slurry, or in the form of a solution comprising component (B) and a solvent, preferably water.

[0071] When added as a slurry or in pure (solid) form, the average particle size D50 of component (B) must be less than 100 μm (D10: 20 μm; D90: 250 μm), preferably less than 50 μm (D10: 12 μm; D90: 200 μm), to achieve the same degree of effectiveness as in solution. Powders that are too coarse may not react completely with the acidic components of the polymer melt and may even cause brownish spots in the product.

[0072] In the context of the present invention, "D10" is understood to mean a particle size where 10% by volume of the particles are equal to or less than D10, based on the total volume of the particles, and 90% by volume of the particles are greater than D10, based on the total volume of the particles. Similarly, "D50" is understood to mean a particle size where 50% by volume of the particles are equal to or less than D50, based on the total volume of the particles, and 50% by volume of the particles are greater than D50, based on the total volume of the particles. Correspondingly, "D90" is understood to mean a particle size where 90% by volume of the particles are equal to or less than D90, based on the total volume of the particles, and 10% by volume of the particles are greater than D90, based on the total volume of the particles.

[0073] To determine particle size, component (B) is suspended in the dry state by compressed air or in a solvent, such as water or ethanol, and the suspension is analyzed. D10, D50, and D90 are determined by laser diffraction using a Malvern Mastersizer 3000. Evaluation is by Fraunhofer diffraction.

[0074] In a preferred embodiment, component (B) in step b) is added to the first mixture (M1) in the form of a solution comprising component (B) and water.

[0075] In a particularly preferred embodiment, in step b), component (A) is reacted with at least one solvent (C A) containing the component (A) dissolved in the solution (S A ) and component (B) is added in the form of at least one solvent (C B ) containing the component (B) dissolved in the solution (S B ) is added.

[0076] Another subject of the present invention is therefore a process for the preparation of a soluble polymer comprising, in step b), reacting component (A) with at least one solvent (C A ) containing the component (A) dissolved in the solution (S A ) and component (B) is added in the form of at least one solvent (C B ) containing the component (B) dissolved in the solution (S B ) is added.

[0077] In this case, the solution (S A ) is preferably a solvent (C A ) and / or water as the solvent (S B ) is preferably a solvent (C B ) includes water.

[0078] Therefore, a first object of the present invention is to i) Solution (S A ) is the solvent (C A ethyl acetate and / or water as the solvent; and / or ii) Solution (S B ) is the solvent (C B ) containing water as It is a method.

[0079] In a most particularly preferred embodiment, in step b), component (A) is treated with at least one solvent (C A ) containing the component (A) dissolved in the solution (S A ) and component (B) is added in solid form at the end of step b) by mixing the first mixture (M1) and component (B) in the solid phase, then proceed to step c).

[0080] Preferably, in step b), in addition to component (A), i) adding sodium carbonate alone to the first mixture (M1) in a concentration ranging from 30 to 120 ppm, preferably from 60 to 70 ppm, based on the total weight of the first mixture (M1); or ii) adding sodium bicarbonate alone to the first mixture (M1) in a concentration ranging from 100 to 300 ppm, preferably from 150 to 200 ppm, based on the total weight of the first mixture (M1); or iii) adding sodium carbonate to the first mixture (M1) at a concentration ranging from 30 to 60 ppm based on the total weight of the first mixture (M1), and sodium bicarbonate to the first mixture (M1) at a concentration ranging from 30 to 200 ppm based on the total weight of the first mixture (M1);

[0081] A first subject of the present invention is therefore a method for preparing a soluble ... i) adding sodium carbonate alone to the first mixture (M1) in a concentration ranging from 30 to 120 ppm based on the total weight of the first mixture (M1), or ii) adding only sodium bicarbonate to the first mixture (M1) in a concentration ranging from 100 to 300 ppm based on the total weight of the first mixture (M1), or iii) adding sodium carbonate to the first mixture (M1) at a concentration ranging from 30 to 60 ppm based on the total weight of the first mixture (M1) and sodium bicarbonate to the first mixture (M1) at a concentration ranging from 30 to 200 ppm based on the total weight of the first mixture (M1); It is a method.

[0082] Preferred combinations are 30 ppm sodium carbonate and 75-85 ppm sodium bicarbonate, 40 ppm sodium carbonate and 65-75 ppm sodium bicarbonate, and 60 ppm sodium carbonate and 60-70 ppm sodium bicarbonate.

[0083] In step b), a second mixture (M2) is obtained, which comprises a polyoxymethylene copolymer (cPOM) and a complex of an acid catalyst and component (A) and / or a reaction product of an acid catalyst and component (B), preferably comprising a polyoxymethylene copolymer (cPOM) and a complex of an acid catalyst and component (A) and a reaction product of an acid catalyst and component (B).

[0084] Step c) In step c), optionally at least one additive is added to the second mixture (M2). Step c) can be carried out after step b). However, it can also be carried out simultaneously with step b).

[0085] As mentioned above, in step b), it is also possible that component (A) is added prior to component (B), and component (B) is added simultaneously with the at least one additive.

[0086] The at least one additive can be added in any known device, preferably in a mixing device.

[0087] The at least one additive is preferably selected from the group consisting of antioxidants, formaldehyde scavengers, UV absorbers, mold release agents, acid scavengers, and nucleating agents.

[0088] Suitable antioxidants are, for example, triethylene glycol bis(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate, sterically hindered phenols such as, for example, BASF SE's Irganox 245. When an antioxidant is used, it is added in an amount such that the polyoxymethylene copolymer (cPOM) contains 0.001 to 10% by weight, preferably 0.05 to 2% by weight, more preferably 0.2 to 0.5% by weight of antioxidant, based on the total weight of the polyoxymethylene copolymer (cPOM).

[0089] Suitable formaldehyde scavengers are, for example, amines, aminotriazine compounds, benzoguanamine, amino acids, hydrazides, urea or urea derivatives, allantoin, guanamine, hydantoin, (modified) melamine or condensates of melamine with formaldehyde, and polyamides, or mixtures thereof. When a formaldehyde scavenger is used, it is added in an amount such that the polyoxymethylene copolymer (cPOM) contains 0.001 to 10% by weight, preferably 0.05 to 2% by weight, more preferably 0.1 to 0.5% by weight of formaldehyde scavenger, based on the total weight of the polyoxymethylene copolymer (cPOM).

[0090] Suitable polyamides are, for example, copolyamides based on caprolactam, hexamethylenediamine, bis(4-aminocyclohexyl)methane, and adipic acid, which may further contain monofunctional polymeric compounds such as propionic acid or triacetonediamine as components for adjusting the molar mass. Examples are Ultramid® 1C and Ultramid® C31 from BASF SE. When polyamides are used, they are added in an amount such that the polyoxymethylene copolymer (cPOM) contains 0.001 to 2 wt. %, preferably 0.05 to 1.5 wt. %, more preferably 0.1 to 0.5 wt. % of polyamide, based on the total weight of the polyoxymethylene copolymer (cPOM).

[0091] Suitable UV absorbers are, for example, hindered amine light stabilizers such as hindered amines of the following polymeric structure: [ka] [In the formula, n is an integer ranging from 5 to 50.] When a hindered amine is used, it is added in an amount such that the polyoxymethylene copolymer (cPOM) accounts for 0.001 to 10% by weight, preferably 0.01 to 1% by weight, and more preferably it may be 0.05 to 0.5% by weight of the hindered amine, based on the total weight of the polyoxymethylene copolymer (cPOM).

[0092] Suitable release agents are, for example, 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 saturated aliphatic alcohols or amines having 2 to 40 carbon atoms, preferably 2 to 6 carbon atoms. When esters or amides are used, they are added in an amount such that the polyoxymethylene copolymer (cPOM) contains 0.01 to 5 wt. %, preferably 0.09 to 1 wt. %, and especially 0.1 to 0.5 wt. % of the release agent, based on the total weight of the polyoxymethylene copolymer (cPOM). Thus, preferred esters or amides are glyceryl distearate, glyceryl tristearate, ethylenediamine distearate, glyceryl monopalmitate, glyceryl trilaurate, glyceryl monobehenate, and pentaerythrityl tetrastearate.

[0093] Suitable acid scavengers other than sodium carbonate and sodium bicarbonate are, for example, alkaline earth carbonates, hydroxides, (hydroxy)stearates, or silicates. When an acid scavenger is used, it is added in an amount such that the polyoxymethylene copolymer (cPOM) contains 0.001 to 2% by weight, preferably 0.01 to 1% by weight, in particular 0.02 to 0.1% by weight, of the acid scavenger, based on the total weight of the polyoxymethylene copolymer (cPOM).

[0094] Suitable nucleating agents are, for example, melamine cyanurate, melamine formaldehyde condensates, silica acid, branched polyoxymethylene, and talc. When a nucleating agent is used, it is added in an amount such that the polyoxymethylene copolymer (cPOM) contains 0.005 to 5 wt. %, preferably 0.01 to 1 wt. %, and in particular 0.02 to 0.2 wt. % of the nucleating agent, based on the total weight of the polyoxymethylene copolymer (cPOM).

[0095] When present, the additives are added in the customary manner, for example individually or collectively, in pure form, as a solution or suspension, or as a masterbatch.

[0096] Step d) In a preferred embodiment, the second mixture (M2) contains 2 to 30 wt. % of unreacted residual monomer, as described above, and 40 to 150 ppm of the complex of the catalyst and triisopropanolamine and the reaction product of the catalyst and component (B).

[0097] Additionally, polyoxymethylene copolymers may contain unstable end groups.

[0098] Thus, in a preferred embodiment, the second mixture (M2) is heat treated to remove residual monomers and depolymerize the unstable end groups in step d) to obtain a third mixture (M3).

[0099] In step d), the second mixture (M2) is treated under vacuum at a temperature in the range of 180-280°C, preferably in the range of 180-260°C, to obtain a third mixture (M3).

[0100] The removal of residual monomers and unstable end groups is usually carried out in the melt using kneading and degassing devices. This finishing process is generally known to those skilled in the art.

[0101] For the polyoxymethylene copolymer (cPOM) and further optionally contained components, such as unreacted residual monomers, the above comments and preferences apply analogously.

[0102] Another object of the present invention is a method for deactivating an acid catalyst during the production of polyoxymethylene copolymers (cPOM), (A) Triisopropanolamine and (B) Sodium carbonate and / or sodium bicarbonate The use of.

[0103] Preferably, components (A) and (B) are used after the polymerization step in the production of polyoxymethylene copolymers (cPOM).

[0104] Another subject of the invention is a method for producing a polymeric molding composition (PM), comprising the steps of: a1) at least one main monomer selected from the group of cyclic formals and a monomer of formula (II) [ka] [In the formula, R 1 ~R 5 and n is as defined above in claim 2. polymerizing at least one first comonomer selected from the group consisting of (a) and (b) and optionally at least one second comonomer in the presence of an acid catalyst to provide a first mixture (M1) comprising a polyoxymethylene copolymer (cPOM) and an acid catalyst; b) (C) Triisopropanolamine and (D) Sodium carbonate and / or sodium bicarbonate is added to the first mixture (M1) to deactivate the acid catalyst, Polyoxymethylene copolymer (cPOM), and a complex of an acid catalyst and component (A), and Reaction product of the acid catalyst and component (B) Obtaining a second mixture (M2) comprising: c) optionally adding at least one additive to the second mixture (M2); d) treating the second mixture (M2) under vacuum at a temperature in the range of 180-280°C, preferably in the range of 180-260°C, to obtain a third mixture (M3); The method includes:

[0105] For steps a1) and b), c) and d) of the method for producing a polymer molding composition (PM), the above-mentioned explanations and preferences regarding the method for deactivating an acid catalyst during the production process of a polyoxymethylene copolymer (cPOM) apply analogously.

[0106] Another subject of the invention is a polymeric molding composition (PM) obtainable by the process described above.

[0107] The polymer molding composition (PM) obtained by the process for producing a polymer molding composition (PM) preferably comprises 60 to 99.99 wt. % polyoxymethylene copolymer (cPOM), 100 to 500 ppm of a complex of an acid catalyst and component (A) and / or a reaction product of an acid catalyst and component (B), and optionally, 0 to 39.99 wt. % of at least one additive selected from the group consisting of antioxidants, formaldehyde scavengers, UV absorbers, mold release agents, acid scavengers, and nucleating agents. Includes.

[0108] Another subject of the invention is the use of the polymeric molding composition (PM) for the production of molded articles.

[0109] The invention will now be explained in more detail by the following examples, without however being limited thereto. [Example]

[0110] Laboratory scale example: Inventive Examples I1 to I27 and Comparative Examples C28 and C29 Examples I31 to I62 of the present invention and Comparative Example C30 a) Material The following ingredients are used: (1) Crude cPOM (corresponding to the first mixture (M1)) Crude cPOM was prepared in a stainless steel beaker equipped with a magnetic stirrer and thermocouple in a fume hood. The stainless steel beaker was placed in a solid aluminum block and adjusted to 80°C. 300 g (96.5 wt. % based on the total amount of monomers used) of 1,3,5-trioxane was melted in a sealed aluminum container at approximately 85°C and transferred to the beaker. In parallel, 10.88 g of 1,3-dioxolane (3.5 wt. % based on the total amount of monomers used) was diluted with 2.798 g of ethyl acetate at room temperature (RT), and 0.0252 g of boron trifluoride diethyl etherate (81 ppm based on the total amount of monomers used) was added. The mixture was poured into 1,3,5-trioxane adjusted to 81°C while stirring. After a few seconds, a white cloudiness appeared, and after a few more seconds, the contents solidified into a white crude cPOM block as the temperature increased. After about 15 minutes, the resulting crude cPOM block is removed from the beaker. After cooling, the crude cPOM block is crushed with a hammer and crushed into small pieces in a Vorwerk Thermomix machine.

[0111] (2) Ingredients used for inactivation: Component (A): Triisopropanolamine (85% in water): BASF SE Ingredient (B-1): Sodium carbonate (Na2CO3, 497-19-8): Honeywell Fluka Component (B-2): Sodium bicarbonate (NaHCO3, 144-55-8): Sigma-Aldrich For comparison: Calcium hydroxide (Ca(OH)2) (1305-62-0): Sigma-Aldrich

[0112] (3) Additives: Ethylene bis(oxyethylene) bis-(3-(5-tert-butyl-4-hydroxy-m-tolyl)-propionate) (36443-68-2): Irganox 245 FF from BASF SE Synthetic magnesium silicate (1343-88-0): Ambosol 500 (PQ Corporation) Talc (14807-96-6): Hydrous magnesium silicate: IT Extra (Mondo) EBS / N,N'-ethylenedi(stearamide) (110-30-5): Acrawax C (Lonza) Polyethylene glycol: Pluriol E8000

[0113] (4) Additional ingredients: Diglyme (bis(2-methoxyethyl) ether)

[0114] b) Deactivation of the catalyst and production of the polymer molding composition (PM) Inventive Examples I1 to I27 and Comparative Examples C28 and C29 Step a) The coarse cPOM powder is placed in a 1 liter HWS container with a Teflon blade stirrer. The HWS container is evacuated and vented with nitrogen three times to remove oxygen and moisture.

[0115] Step b) Addition of component (A) Add 0.12 g of triisopropanolamine (85% in water) and 15 μL of water to 12 mL of diglyme, and spray the resulting solution onto the crude cPOM powder with a nebulizer. The crude cPOM is then heated to 60 °C in a preheated oil bath with vigorous stirring and stirred under a nitrogen stream for 1 h. It is then cooled under nitrogen.

[0116] Addition of component (B) or Ca(OH)2 (for comparison) 25 g of crude cPOM powder treated with component (A) was placed in a 250 mL flask with a Teflon blade stirrer. Depending on the required amount of component (B) shown in Tables 1, 2, and 3, the corresponding amount of a 5 wt. % aqueous solution / slurry of component (B) (Na2CO3 and / or NaHCO3) or Ca(OH)2) was made up to 1 mL with diglyme and sprayed onto the cPOM powder with a nebulizer. The cPOM was then heated to 60 °C in a preheated oil bath and stirred under a nitrogen flow for 1 hour. It was then cooled to 50 °C under nitrogen to obtain a second mixture (M2).

[0117] Step c) Addition of additives An additive mixture containing 3 parts by weight of Irganox 245 FF, 0.5 parts by weight of synthetic magnesium silicate, 0.4 parts by weight of talc, 1.5 parts by weight of EBS, and 2 parts by weight of Pluriol E8000 (based on the total weight of the additive mixture) was ground in a laboratory mill to obtain a fine, homogeneous powder, which was then added to the second mixture (M2) in an amount of 0.74%. To achieve this, 29.6% by weight (7.4 g) of the powder mixture was filled with diglyme to a volume of 40 mL and shaken thoroughly. 1 mL of the resulting additive solution / slurry was sprayed onto the mixture (M2) and then stirred at 50°C for 30 minutes under nitrogen.

[0118] In steps b) and c), diglyme is used as a carrier medium to ensure uniform and complete addition of the components.

[0119] Step d) Melting of the second mixture (M2) The second mixture (M2) treated with the additive solution is filled into a 250 mL HWS container, and its bottom is rubbed with Teflon paste to form a very thin film to prevent adhesion to the glass. The container is placed under vacuum (approximately 100 mbar) and nitrogen and immersed in an oil bath preheated to 210 °C. After 10-15 minutes, the second mixture (M2) treated with the additive solution is completely melted and gas formation ceases (there is virtually no further bubble formation; the third mixture (M3)). After the container cools, the POM peels off from the glass wall as a carrot.

[0120] Examples I31 to I62 of the present invention and Comparative Example C30 Step a) For each example, 25 g of crude cPOM powder is placed in a flask.

[0121] Step b) Addition of components (A) and (B) A 7.51 wt % solution of triisopropanolamine in ethyl acetate (component (A)) and one of the 5 wt % aqueous solutions / slurries of component (B) (Na2CO3 or NaHCO3) are added by the method shown in Table 4 and heated to 60°C with stirring in a nitrogen flow for a predetermined time to obtain a second mixture (M2).

[0122] Step c) Addition of additives 185 mg of an additive mixture containing 0.3 wt. % Irganox 245 FF, 0.05 wt. % synthetic magnesium silicate, 0.04 wt. % talc, 0.15 wt. % EBS, and 0.2 wt. % Pluriol E8000 (based on the total weight of the second mixture (M2)) is added to the second mixture (M2) over a predetermined period of time while stirring.

[0123] Step d) Melting of the second mixture (M2) The second mixture (M2) treated with the additive mixture is filled into a 250 mL HWS container, and its bottom is rubbed with Teflon paste to form a very thin film to prevent adhesion to the glass. The container is placed under vacuum (approximately 100 mbar) and nitrogen and immersed in an oil bath preheated to 210 °C. After 15 minutes, the second mixture (M2) treated with the additive mixture is completely melted and gas formation ceases (there is virtually no further bubble formation; the third mixture (M3)). After the container cools, the POM peels off from the glass wall as a carrot.

[0124] c) Analysis method To determine the weight loss at 222°C and the content of extractable formaldehyde (FA), the carrots obtained above are ground and the resulting powder is degassed at 140°C for 5 hours.

[0125] Weight loss N2 (determination of weight loss under nitrogen atmosphere): To test thermal stability, the weight loss at 222°C under a slow N2 flow is determined. This is the weight loss in percent of a weighed sample of approximately 1 g of powder when heated at 222°C under nitrogen for 2 hours. After cooling, the sample is reweighed and the weight loss is calculated.

[0126] Extractable Formaldehyde (FA) Content: The extractable FA content is determined as follows: 5 g of POM powder with a particle size of less than 0.5 mm and 10 g of deionized water are charged into a 250 mL round-bottom flask equipped with a reflux condenser and an oval magnetic bar. An aluminum block that fits the round shape of the flask is heated to 120 °C on a magnetic stirring / heating plate. The flask is lowered onto the aluminum block, stirring is initiated, and the start of boiling is monitored and timed. This procedure is continued for 50 or 100 minutes, respectively, with gentle reflux. After rapid cooling and settling of the powder, the aqueous phase is aspirated through a syringe filter and sent for formaldehyde determination by the photometric acetylacetone method described by Kakac and Vejdelek, Handbuch der photometrischen Analyse organischer Verbindungen, Verlag Chemie, Weinheim (1974): formaldehyde is reacted with two equivalents of acetylacetone and one equivalent of ammonia to produce 3,5-diacetyl-1,4-dihydrolutidine, which is then determined photometrically at a wavelength of 412 nm with a baseline correction of 495 nm.

[0127] Pellet Color: b * The color values ​​are determined based on the flat, hemispherical underside of the carrot. * Values ​​are given. Negative values ​​indicate a bluish tint, and positive values ​​indicate a yellow to brownish tint. Bluish to neutral tints are preferred.

[0128] yellowness index, YI The yellowness index (YI) is determined according to DIN 6167. Both the color and the yellowness index are determined by a Konica Minolta spectrophotometer CM-3600d, and the data are processed by the respective color data software CM-S 100w Spectra Magic NX. The preferred YI value is in the range of -2 to 2.

[0129] Drinking water test (migration test) The test is carried out according to the procedure described in DIN EN 12873-1 and -2. First, 2 mm thick plaques are pressed at 190 ° C, wired, completely immersed in deionized water and stored in screw-cap jars at exactly 85 ° C. After exactly one day, the water is removed, the plaques are rinsed with tap water for 1 hour and extracted again with fresh deionized water. The formaldehyde content of the extracted water at the specified days is determined, and the content of FA in ppm is calculated based on the 100 cm 2 and normalized to 100 mL of water. This results in decay curves that tend to zero for the inventive example and remain unacceptably high for the comparative example. These results are shown in Tables 5 and 6.

[0130] Extrusion tests (Table 5) are carried out in a twin-shaft Xplore® MC 15 microcompounder from Xplore Instruments BV, charged with 19 g of powder. The melt is compounded at 190°C and 100 rpm for 5 and 10 minutes, respectively, and then discharged as a strand, which is granulated for thermal testing (weight loss). A portion of the melt is collected on a Teflon pad and then pressed into plaques for color measurement.

[0131] d) Results Inventive Examples I1 to I27 and Comparative Examples C28 and C29

[0132] [Table 1]

[0133] [Table 2]

[0134] [Table 3]

[0135] The results in Tables 1-3 show that using carbonate and / or sodium bicarbonate (component (B)) to deactivate the catalyst results in a lower extractable FA content compared to the deactivator Ca(OH)2 used in the prior art. To achieve an acceptable low extractable FA content, using component (B) requires a concentration of only 40 ppm sodium carbonate or 160 ppm sodium bicarbonate to produce a product within the desired color range, whereas using Ca(OH)2 requires a concentration of at least 150 ppm, which already results in a significant yellowish discoloration. The combination of sodium carbonate and sodium bicarbonate allows for a low extractable FA content and a neutral color. Furthermore, the use of components (A) and (B) at the appropriate concentrations does not adversely affect the color of the cPOM. In contrast, deactivation with calcium hydroxide results in either a white product with a high extractable FA content or a product with a low extractable FA content but an unacceptable yellowish-brownish discoloration.

[0136] Inventive Examples I31-I62 and Comparative Example C30

[0137] [Table 4-1] [Table 4-2] [Table 4-3]

[0138] [Table 5]

[0139] [Table 6]

[0140] Pilot scale example: Examples I66 to I71 of the present invention and Comparative Example C75 a) Material The following ingredients are used: (1) Crude cPOM (corresponding to the first mixture (M1)) 300 g (96.5 wt. % based on the total amount of monomers used) of 1,3,5-trioxane are melted in a 500 mL aluminum bottle at 80 °C. In parallel, 10.88 g of 1,3-dioxolane (3.5 wt. % based on the total amount of monomers used) are placed in a screw-cap jar at room temperature and mixed with 2.80 g (3.10 mL) of boron trifluoride diethyl etherate (0.9% in ethyl acetate, corresponding to 0.0252 g of boron trifluoride diethyl etherate (81 ppm based on the total amount of monomers used)). This mixture is added to the 1,3,5-trioxane melt with a syringe, the needle reaching almost to the bottom. After a brief swirling period of 1-2 seconds, the starting mixture is immediately poured into a kneader (2-liter mixing and kneading machine type LKS 1 from Linden, usable volume 1 liter) adjusted to 60 °C. After a few seconds, the viscosity of the liquid mixture increases, it becomes cloudy, dough-like at first, then solid, and is pulverized by two rotating kneading blades (speed: 75 rpm). Finally, the coarse cPOM is converted into powder form. After 5 minutes, the deposits on the walls and kneading elements are knocked off for a short time (3 minutes) and then pulverized again for a further period (5 minutes).

[0141] (2) Ingredients used for inactivation: The quenching uses the same ingredients as described above in the laboratory scale example.

[0142] (3) Additives: The same additives are used as described above in the laboratory scale example.

[0143] b) Deactivation of the catalyst and production of the polymer molding composition Step a) Step a) is carried out as described in a) Materials (1).

[0144] Steps b), c), and d) Addition of component (A) 1.60 g of triisopropanolamine solution is applied to the top of the crude cPOM powder with a syringe. The triisopropanolamine solution is prepared by mixing 3.9 g of 85 wt % aqueous triisopropanolamine and 48.1 g of ethyl acetate. The treated powder is kneaded at 60°C for 5 minutes. It is then removed from the kneader and ground into a powder in a Vorwerk Thermomix machine (yield: 290 g; 93%). The powder is then conditioned under nitrogen at 60°C for 1 hour in a 2-liter HWS container with a Teflon-blade stirrer. Total yield: 255g (85%)

[0145] Addition of component (B) or Ca(OH)2 (for comparison), and addition of additives According to Table 7, component (B) / Ca(OH)2 and additives are added to a 250 mL HWS container and the powder mixture is vigorously stirred with a blade stirrer under a gentle nitrogen flow at 50°C for 30 minutes, then melted at 210°C (step d)).

[0146] c) Analysis method The same analytical methods are used as described above in the laboratory scale example.

[0147] d) Results

[0148] [Table 7]

[0149] Table 7 shows that for carrots, 60-66 ppm solid sodium carbonate (Na2CO3) provides the best compromise between weight loss and yellowness index, while calcium hydroxide (Ca(OH)2) provides inferior color at comparable weight loss. For similar results, 66-72 ppm sodium carbonate powder is required for a 5-minute extrusion, and about 66 ppm for a 10-minute extrusion. The efficiency of ground sodium carbonate powder is similar to that of aqueous sodium carbonate solution.

Claims

1. 1. A method for deactivating an acid catalyst during a process for producing polyoxymethylene copolymer (cPOM), the method comprising: a) providing a first mixture (M1) comprising the polyoxymethylene copolymer (cPOM) and the acid catalyst; b) (A) triisopropanolamine, and / or (B) sodium carbonate and / or sodium bicarbonate to the first mixture (M1) to deactivate the acid catalyst, the polyoxymethylene copolymer (cPOM), and a complex of the acid catalyst and component (A), and / or A reaction product of the acid catalyst and component (B) obtaining a second mixture (M2) comprising: c) optionally adding at least one additive to said second mixture (M2); d) treating said second mixture (M2) under vacuum at a temperature in the range of 180-280°C to obtain a third mixture (M3); A method comprising:

2. The polyoxymethylene copolymer (cPOM) is a copolymer of 60 to 99.99 mol % of —CH ２ O-repeating units and 0.01 to 40 mol % of formula (I) 【Chemistry 1】 [In the formula, R １ ~R ４ are each independently a hydrogen atom, C １ ~C ４ an alkyl group or an alkoxy-substituted alkyl group having 1 to 4 carbon atoms; R ５ is a chemical bond, -CH ２ -, -OCH ２ -, C １ ~C ４ Alkyl or C １ ~C ４ an alkoxy-substituted methylene group, or the corresponding oxymethylene group, and n is 0 to 3. The method of claim 1 , comprising repeating units according to

3. Step a) a1) at least one main monomer selected from the group of cyclic formals and a monomer of formula (II) 【Chemistry 2】 [In the formula, R １ ~R ５ and n is as defined above in claim 2. and optionally at least one second comonomer selected from the group consisting of:

3. The method of claim 1 or 2, comprising:

4. The acid catalyst is i) at least one acid catalyst selected from the group consisting of boron trifluoride, coordination complexes of boron trifluoride with water, coordination complexes of boron trifluoride with dialkyl ethers, and catalytically active conversion products of the aforementioned acid catalysts; and / or ii) in step a) is present in an amount of 10 to 150 ppm based on the total weight of said first mixture (M1); and / or iii) in step a1), present in an amount of 10 to 150 ppm based on the total weight of the primary monomer and the comonomer; 4. The method according to any one of claims 1 to 3.

5. 5. The method according to claim 1, wherein in step b) components (A) and (B) are added simultaneously.

6. 5. The method of claim 1, wherein in step b) component (A) is added before component (B).

7. In step b), component (A) is mixed with at least one solvent (C Ａ a solution (S) containing the component (A) dissolved in Ａ ) and component (B) is added in the form of at least one solvent (C Ｂ ) a solution (S Ｂ 7. The method according to claim 1, wherein the hydroxybenzoate is added in the form of hydroxybenzoate.

8. i) the solution (S Ａ ) is a solvent (C Ａ ethyl acetate and / or water as the solvent; and / or ii) the solution (S Ｂ ) is a solvent (C Ｂ ) containing water as The method of claim 7.

9. 5. The method of claim 1, wherein in step b) component (A) is added prior to component (B), and component (B) is added simultaneously with the at least one additive.

10. In step b), in addition to component (A), i) adding sodium carbonate alone to said first mixture (M1) in a concentration ranging from 30 to 120 ppm based on the total weight of said first mixture (M1), or ii) adding sodium bicarbonate alone to said first mixture (M1) in a concentration ranging from 100 to 300 ppm based on the total weight of said first mixture (M1), or iii) adding sodium carbonate to the first mixture (M1) at a concentration ranging from 30 to 60 ppm, based on the total weight of the first mixture (M1), and sodium bicarbonate to the first mixture (M1) at a concentration ranging from 30 to 200 ppm, based on the total weight of the first mixture (M1); 10. The method according to any one of claims 1 to 9.

11. For deactivating acid catalysts during the production of polyoxymethylene copolymers (cPOMs), (A) triisopropanolamine and (B) sodium carbonate and / or sodium bicarbonate Use of.

12. 1. A method for producing a polymer molding composition (PM), comprising: a1) at least one main monomer selected from the group of cyclic formals and a monomer of formula (II) 【Transformation 3】 [In the formula, R １ ~R ５ and n is as defined above in claim 2. and optionally at least one second comonomer in the presence of an acid catalyst to provide a first mixture (M1) comprising a polyoxymethylene copolymer (cPOM) and said acid catalyst; b) (A) triisopropanolamine, and (B) sodium carbonate and / or sodium bicarbonate to the first mixture (M1) to deactivate the acid catalyst, the polyoxymethylene copolymer (cPOM), and a complex of the acid catalyst and component (A), and A reaction product of the acid catalyst and component (B) obtaining a second mixture (M2) comprising: c) optionally adding at least one additive to said second mixture (M2); d) treating said second mixture (M2) under vacuum at a temperature in the range of 180-280°C to obtain a third mixture (M3); A method comprising:

13. A polymeric molding composition (PM) obtainable by the method according to claim 12.

14. 14. Use of a polymer molding composition (PM) according to claim 12 or 13 for the production of moldings.

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