WO2022258570A1

WO2022258570A1 - Process for producing polyoxymethylene-polyoxyalkylene copolymers

Info

Publication number: WO2022258570A1
Application number: PCT/EP2022/065321
Authority: WO
Inventors: Karolina WALKER; Aurel Wolf; Mike SCHUETZE; Christoph Guertler
Original assignee: Covestro Deutschland Ag
Priority date: 2021-06-10
Filing date: 2022-06-07
Publication date: 2022-12-15

Abstract

The present invention describes a process for producing a polyoxymethylene-polyoxyalkylene copolymer, comprising reacting a polymeric formaldehyde compound with an alkylene oxide in the presence of a double metal cyanide (DMC) catalyst, the polymeric formaldehyde compound having at least one terminal hydroxyl group. The process comprises providing a suspending agent in a reactor and copolymerizing the polymeric formaldehyde compound with the alkylene oxide, copolymerization taking place at a reactor temperature of 72°C to 84°C. The invention further relates to a polyoxymethylene-polyoxyalkylene copolymer that can be obtained by means of such a process and to the use of same for producing a polyurethane polymer.

Description

Process for preparing polyoxymethylene-polyoxyalkylene copolymers

The present invention describes a process for the preparation of a polyoxymethylene polyoxyalkylene copolymer comprising the reaction of a polymeric formaldehyde compound with an alkylene oxide in the presence of a double metal cyanide (DMC) catalyst, the polymeric formaldehyde compound having at least one terminal hydroxyl group, the process comprising the submission of a suspending agent in a reactor and a copolymerization of the polymeric formaldehyde compound with the alkylene oxide, wherein the copolymerization takes place at a reactor temperature of 72°C to 84°C. It also relates to a polyoxymethylene-polyoxyalkylene copolymer obtainable by such a process and its use for the production of a polyurethane polymer.

WO2015/155094 A1 discloses a process for preparing polyoxymethylene block copolymers, comprising the step of activating the DMC catalyst in the presence of an OH-terminated polymeric formaldehyde compound with a defined amount of alkylene oxide at 40° C. to 150° C., and subsequent polymerization with alkylene oxides at 100 °C. ln WO2020/114751 Al a process for preparing polyoxymethylene-polyalkylene oxide block copolymers is disclosed, comprising the step of polymerizing an alkylene oxide in the presence of an OH-terminated polyoxymethylene polymer as polymeric formaldehyde starter compound and a catalyst, the polyoxymethylene polymer having a number-average molecular weight Mn , from > 1100 g/mol to <2300 g/mol. The copolymerization of the alkylene oxide with the polymeric formaldehyde starter compound is carried out at a reactor temperature of 70.degree. ln WO 2020/083814 A1 a process for preparing a polyoxymethylene-polyoxyalkylene block copolymer is disclosed comprising the reaction of a polymeric formaldehyde compound with alkylene oxides in the presence of a double metal cyanide (DMC) catalyst and an H-functional starter substance at a reactor temperature of 70° C., where the theoretical molar mass of the polymeric formaldehyde compound is smaller than the theoretical molar mass of the H-functional starter substance. In the not yet published application PCT/EP2020/085885, a process for preparing a polyoxymethylene polyoxyalkylene copolymer is disclosed comprising the reaction of a polymeric formaldehyde compound with an alkylene oxide in the presence of a double metal cyanide (DMC) catalyst, the process comprising the submission of a suspending agent in a Reactor and subsequent copolymerization of the polymeric formaldehyde compound with the alkylene oxide at a reactor temperature of 70°C or 90°C. Based on the prior art, the task therefore arose of providing a simple and economically advantageous one-step process for the preparation of polyoxymethylene-polyoxyalkylene copolymers by reacting oligomeric and polymeric forms of formaldehyde as a starter substance with alkylene oxides, with the reactants being reacted as completely as possible However, possible side reactions are to be reduced as much as possible. These side reactions can be, for example, due to base-catalyzed rearrangement reactions of formaldehyde to form monofunctional formates or the depolymerization of the oligomeric and polymeric forms of formaldehyde to form low molecular weight or molecular forms of formaldehyde. In particular, the formation of monofunctional formate by-products leads to a reduction in the hydroxyl functionality of the resulting polyoxymethylene-polyoxyalkylene copolymer product, which is disadvantageous for further processing, for example to give polyurethanes with defined properties. It is therefore an object of this invention to also provide a process which corresponds to polyoxymethylene-polyalkylene oxide copolymer products with a final hydroxyl group functionality close to the theoretical functionality based on the functionality of the polymeric formaldehyde compound used.

Furthermore, it was also an object of the present invention to increase process reliability by reducing pressure increases during the copolymerization. Pressure increases, in particular unwanted pressure increases, during the copolymerization process can require a correction of the process or even a shutdown of the plant to a safe operating condition, so that the process efficiency is significantly impaired.

This object is achieved according to the invention by a process for preparing a polyoxymethylene-polyoxyalkylene copolymer comprising the reaction of a polymeric formaldehyde compound with an alkylene oxide in the presence of a double metal cyanide (DMC) catalyst; wherein the polymeric formaldehyde compound has at least one terminal hydroxyl group; the method comprising the following steps:

(a) Submission of a suspending agent in a reactor

(g) copolymerizing the polymeric formaldehyde compound with the alkylene oxide, and wherein step (g) occurs at a reactor temperature of from 72°C to 84°C.

The use of the word a in connection with countable quantities is to be understood here and in the following only as a numeral if this is clear from the context (e.g. with the wording “exactly one”). Otherwise, expressions such as “an alkylene oxide”, “a polymeric formaldehyde compound” etc. always also include embodiments in which two or more alkylene oxides, two or more polymeric formaldehyde compounds etc. are used.

The invention is explained in detail below. Various embodiments can be combined with one another as desired, as long as the context does not clearly indicate the opposite to the person skilled in the art.

For the purposes of the invention, polyoxymethylene copolymers refer to polymeric compounds which contain polyoxymethylene units and polyoxyalkylene and/or polyoxyalkylene carbonate units, preferably polyoxyalkylene units. In one embodiment of the method according to the invention, the polyoxymethylene-polyoxyalkylene copolymer has a number-average molecular weight of 1000 g/mol to 10000 g/mol, preferably 1000 g/mol to 5000 g/mol, particularly preferably 1000 g/mol to 3000 g/mol on, the number-average molecular weight being determined by means of gel permeation chromatography (GPC) based on DIN 55672-1: "Gel permeation chromatography, part 1 - tetrahydrofuran as eluent", polystyrene samples of known molecular weight being used for calibration.

The polyoxymethylene copolymers obtained offer a number of advantages over existing polymers. Certain physical properties such as glass transition temperatures, melting ranges, viscosities and solubilities, etc. can be controlled in a targeted manner via the length of the polyoxymethylene blocks in relation to the oligomeric polyoxyalkylene blocks.

Compared to polyoxymethylene homopolymers of the same molecular weight, the partial crystallinity in the polyoxymethylene-polyoxyalkylene copolymers according to the invention is typically reduced, which usually also leads to a reduction in glass transition temperatures, melting points and viscosities, etc. Furthermore, the presence of additional polyoxyalkylene blocks typically results in a significant increase in chemical and thermal stability. In addition, the resulting polyoxymethylene-polyoxyalkylene copolymers generally have good solubilities in various solvents, can usually be melted easily and without loss of mass, or are in the liquid state even at low temperatures. Compared to polyoxymethylene homopolymers, the polyoxymethylene-polyoxyalkylene copolymers thus exhibit significantly better processability.

Compared to polyether polyols of the same molecular weight, the proportion of polyoxyalkylene units produced from the corresponding alkylene oxides is reduced by the proportion of polyoxymethylene, which contributes to the advantageous economics of the product. Various physical properties such as glass transition temperatures, melting ranges, viscosities, solubility, etc. can be specifically controlled for a given molecular weight via the proportion of polyoxymethylene in relation to the polyoxyalkylene and via the molecular weight of the polymeric formaldehyde compound used.

This can result in advantageous physical properties, in particular of secondary products of these polymers, and thus enable new applications.

In the context of the entire invention, the term “alkyl” generally includes substituents from the group n-alkyl such as ethyl or propyl, but not methyl, branched alkyl and/or cycloalkyl. In the context of the entire invention, the term "aryl" generally includes substituents from the group of carbo- or heteroaryl substituents such as phenyl and/or polynuclear carbo- or heteroaryl substituents, which may be bonded with further alkyl groups and/or heteroatoms such as nitrogen, oxygen, silicon, sulfur or phosphorus can be substituted. The radicals R1, R2, R3 and/or R4 can be linked to one another within a repeating unit in such a way that they form cyclic structures, such as, for example, a cycloalkyl radical which is incorporated into the polymer chain via two adjacent carbon atoms.

Suitable polymeric formaldehyde compounds for the process according to the invention are in principle those oligomeric and polymeric forms of formaldehyde which have at least one terminal hydroxyl group for reaction with the alkylene oxides and any other comonomers. According to the invention, the term “terminal hydroxyl group” is understood in particular to mean a terminal hemiacetal functionality which results as a structural feature via the polymerization of the formaldehyde. For example, the starter compounds can be oligomers and polymers of formaldehyde of the general formula (11)

HO-(CH ₂ O) _n -H (11) where n is an integer > 2 and where polymeric formaldehyde typically has n > 8 repeat units.

Polymeric formaldehyde compounds suitable for the process according to the invention generally have molar masses of 62 to 30000 g/mol, preferably 62 to 12000 g/mol, particularly preferably 242 to 6000 g/mol and very particularly preferably 242 to 3000 g/mol and comprise from 2 to 1000, preferably from 2 to 400, particularly preferably from 8 to 200 and very particularly preferably from 8 to 100 oxymethylene repeating units n. The compounds used in the process according to the invention typically have a functionality (F) of 1 to 3 in In certain cases, however, these can also be higher-functional, i.e. have a functionality > 3. Preference is given to using open-chain polymeric formaldehyde compounds with terminal hydroxyl groups in the process according to the invention Functionality from 1 to 10, preferably from 1 to 5, more preferably from 2 to 3 have. Linear polymeric formaldehyde compounds which have a functionality of 2 are very particularly preferably used in the process according to the invention. The functionality F corresponds to the number of OH end groups per molecule.

The polymeric formaldehyde compounds used for the process according to the invention can be prepared by known processes (cf. e.g. M. Haubs et al., 2012, Polyoxymethylenees, Ullmann's Encyclopedia of Industrial Chemistry; G. Reus et al., 2012 , formaldehydes, ibid.). In principle, the formaldehyde compounds can also be used in the form of a copolymer in the process according to the invention. Further suitable formaldehyde copolymers for the process according to the invention are copolymers of formaldehyde and of trioxane with cyclic and/or linear formals, such as butanediol formal. It is also conceivable that higher homologous aldehydes, such as acetaldehyde, propionaldehyde, etc., are incorporated into the formaldehyde polymer as comonomers. It is also conceivable that formaldehyde compounds according to the invention are in turn produced starting from H-functional starter compounds; in particular, polymeric formaldehyde compounds with a hydroxyl end group functionality F>2 can be obtained here by using polyvalent compounds (cf. e.g. WO 1981001712 A1, Bull. Chem. Soc. J., 1994, 67, 2560-2566, US 3436375, JP 03263454, JP 2928823).

As is known, formaldehyde polymerizes even through the presence of small traces of water. In aqueous solution, a mixture of oligomers and polymers of different chain lengths is formed depending on the concentration and temperature of the solution, which are in equilibrium with molecular formaldehyde and formaldehyde hydrate. So-called paraformaldehyde precipitates out of the solution as a white, poorly soluble solid and is usually a mixture of linear formaldehyde polymers with n=8 to 100 repeating oxymethylene units.

An advantage of the process according to the invention is in particular that polymeric formaldehyde or so-called paraformaldehyde, which is commercially and inexpensively available, can be used directly as a reactant without the need for additional preparatory steps. In an advantageous embodiment of the invention, paraformaldehyde is therefore used as the reactant deployed.

Preference is given here to linear formaldehyde compounds of the general formula (11) HO—(CH ₂ O)nH, where n is an integer >2, preferably where n=2 to 1000, particularly preferably where n=2 to 400 and very particularly preferred with n = 8 to 100, used with two terminal hydroxyl groups. In particular, mixtures of polymeric formaldehyde compounds of the formula HO-(CH ₂ 0)nH, each with different values for n can be used. In an advantageous embodiment, the mixtures of polymeric formaldehyde compounds of the formula (II) used contain HO-(CH ₂ 0)nH at least 1% by weight, preferably at least 5% by weight and particularly preferably at least 10% by weight of polymeric formaldehyde Compounds with n > 20.

In a preferred embodiment of the method according to the invention, the polymeric formaldehyde compound has 2 hydroxyl groups and 8 to 100 oxymethylene repeating units (s) or 3 hydroxyl groups and 8 to 100 oxymethylene repeating units (n).

Compounds of the general formula (IV) used as the epoxide alkylene oxide (epoxide) for the preparation of the polyoxymethylene copolymers:

used, where R ¹ , R ² , R ³ and R ⁴ are independently hydrogen or an optionally additional heteroatoms such as nitrogen, oxygen, silicon, sulfur or phosphorus-containing alkyl or aryl radical and can optionally be linked together so that they form cyclic structures, such as a cycloalkylene oxide.

In the process according to the invention it is possible in principle to use those alkylene oxides which are suitable for the polymerization in the presence of a DMC catalyst. If different alkylene oxides are used, they can be metered in either as a mixture or one after the other. In the case of the latter method of dosing, the polyether chains of the polyoxymethylene-polyoxyalkylene copolymer obtained in this way can in turn also have a copolymer structure.

In general, alkylene oxides (epoxides) having 2-24 carbon atoms can be used for the process according to the invention. The alkylene oxides having 2-24 carbon atoms are, for example, one or more compounds selected from the group consisting of ethylene oxide, propylene oxide, 1-butene oxide, 2,3-butene oxide, 2-methyl-1,2-propene oxide (isobutene oxide), 1-pentene oxide, 2,3-pentene oxide, 2-methyl-1,2-butene oxide, 3-methyl-1,2-butene oxide, 1-hexene oxide, 2,3-hexene oxide, 3,4-hexene oxide, 2-methyl- 1,2-pentene oxide, 4-methyl-1,2-pentene oxide, 2-ethyl-1,2-butene oxide, 1-heptene oxide, 1-octene oxide, 1-nonene oxide, 1-decene oxide, 1-undecene oxide, 1-dodecene oxide, 4-Methyl-1,2-pentene oxide, butadiene monoxide, isoprene monoxide, cyclopentene oxide, cyclohexene oxide, cycloheptene oxide, cyclooctene oxide, styrene oxide, methyl styrene oxide, pinene oxide, mono- or polyepoxidized fats as mono-, di- and triglycerides, epoxidized fatty acids, C1-C24 Esters of epoxidized fatty acids, epichlorohydrin, glycidol, and derivatives of glycidol such as for example methyl glycidyl ether, ethyl glycidyl ether, 2-ethylhexyl glycidyl ether, allyl glycidyl ether, glycidyl methacrylate and epoxy-functional alkoxysilanes such as 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilane, 3-

glycidyloxypropyltripropoxysilane, 3-glycidyloxypropylmethyldimethoxysilane, 3-glycidyloxypropylethyldiethoxysilane, 3-glycidyloxypropyltriisopropoxysilane. The epoxide of the general formula (1) is preferably a terminal epoxide, where R1, R2 and R3 are hydrogen, and R4 can be hydrogen, an alkyl or aryl radical optionally containing additional heteroatoms such as nitrogen, oxygen, silicon, sulfur or phosphorus and can differ in different repeat units. In a preferred embodiment of the process according to the invention, the alkylene oxide is one or more compound(s) and is selected from the group consisting of ethylene oxide, propylene oxide, styrene oxide and cyclohexene oxide, preferably ethylene oxide and propylene oxide and particularly preferably propylene oxide. In one embodiment of the process according to the invention, a suspension medium is used, the suspension medium used preferably containing no H-functional groups. All polar-aprotic, weakly polar-aprotic and non-polar-aprotic solvents which do not contain any H-functional groups are suitable as suspension media without H-functional groups. A mixture of two or more of these suspending agents can also be used as the suspending agent. In one embodiment of the method according to the invention, the suspending agent that does not contain any H-functional groups is one or more compound(s) and is selected from the group consisting of 4-methyl-2-oxo-1,3-dioxolane, 1,3 -Dioxolan-2-one, acetone, methyl ethyl ketone, acetonitrile, nitromethane, dimethyl sulfoxide, sulfolane, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, dioxane, diethyl ether, methyl tert-butyl ether, tetrahydrofuran, ethyl acetate, butyl acetate, pentane, n-hexane, benzene , toluene, xylene, ethylbenzene, chloroform, chlorobenzene, dichlorobenzene and carbon tetrachloride.

4-Methyl-2-oxo-1,3-dioxolane, 1,3-dioxolan-2-one, toluene, xylene, ethylbenzene, chlorobenzene and dichlorobenzene and mixtures of two or several of these suspending agents used, particularly preferably 4-methyl-2-oxo-l, 3-dioxolane and 1,3-dioxolan-2-one and toluene or a mixture of 4-methyl-2-oxo-l, 3-dioxolane and 1,3 dioxolan-2-one and/or toluene. It is likewise also possible to use a further starter compound, which is in liquid form under the reaction conditions, as a suspension medium in a mixture with the polymeric formaldehyde starter compound. In an alternative embodiment of the process according to the invention, in step (a) a suspension medium containing H-functional groups is initially charged together with DMC catalyst in the reactor. In a preferred embodiment, the suspension medium containing H-functional groups contains the DMC catalyst , a polyoxymethylene-polyoxyalkylene copolymer obtainable from a preceding production process containing an activated DMC catalyst. In this way, possible separation steps are saved compared to the use of a suspending agent that does not have any H-functional groups, resulting in a simpler and more efficient process.

The double metal cyanide compounds present in the process according to the invention which can preferably be used in the process according to the invention are the reaction products of water-soluble metal salts and water-soluble metal cyanide salts.

Double metal cyanide (DMC) catalysts for use in the homopolymerization of alkylene oxides are known in principle from the prior art (see e.g. US-A 3,404,109, US-A 3,829,505, US-A 3,941,849 and US-A 5 158 922). DMC catalysts described, for example, in US-A-5,470,813, EP-A-700,949, EP-A-743,093, EP-A-761,708, WO 97/40086, WO 98/16310 and WO 00/47649 a very high activity and enable the production of polyether carbonates at very low catalyst concentrations. A typical example are the highly active DMC catalysts described in EP-A 700 949, which, in addition to a double metal cyanide compound (e.g. zinc hexacyanocobaltate(III)) and an organic complex ligand (e.g. tert-butanol), also contain a polyether with a number-average molecular weight greater than Contain 500 g/mol.

The DMC catalysts that can be used according to the invention are preferably obtained by (1.) in the first step reacting an aqueous solution of a metal salt with the aqueous solution of a metal cyanide salt in the presence of one or more organic complex ligands, e.g. an ether or alcohol,

(2.) where, in the second step, the solid is separated from the suspension obtained from (a) by known techniques (such as centrifugation or filtration),

(3.) Where appropriate, in a third step, the isolated solid is washed with an aqueous solution of an organic complex ligand (e.g. by resuspension and subsequent renewed isolation by filtration or centrifugation),

(4.) the resulting solid then being dried, optionally after pulverization, at reactor temperatures of generally 20-120° C. and at pressures of generally 0.1 mbar to normal pressure (1013 mbar), and in the first step or directly after the precipitation of the double metal cyanide compound (second step) one or more organic complex ligands, preferably in excess (based on the double metal cyanide compound) and optionally further complex-forming components are added.

The double metal cyanide compounds present in the DMC catalysts which can be used according to the invention are the reaction products of water-soluble metal salts and water-soluble metal cyanide salts.

For example, an aqueous zinc chloride solution (preferably in excess, based on the metal cyanide salt) and potassium hexacyanocobaltate are mixed and then dimethoxyethane (glyme) or tert-utanol (preferably in excess, based on zinc hexacyanocobaltate) is added to the suspension formed.

Metal salts suitable for preparing the double metal cyanide compounds preferably have a composition according to the general formula (V),

M(X) _n (V), where

M is selected from the metal cations Zn ²⁺ , Fe ²⁺ , Ni ²⁺ , Mn ²⁺ , Co ²⁺ , Sr ²⁺ , Sn ²⁺ , Pb ²⁺ and Cu ²⁺ , M is preferably Zn ²⁺ , Fe ²⁺ , Co ²⁺ or Ni ²⁺ ,

X is one or more (i.e. different) anions, preferably an anion selected from the group consisting of halides (i.e. fluoride, chloride, bromide, iodide), hydroxide, sulfate, carbonate, cyanate, thiocyanate, isocyanate, isothiocyanate, carboxylate, oxalate and nitrate ; n is 1 when X=sulfate, carbonate or oxalate and n is 2 when X=halide, hydroxide, carboxylate, cyanate, thiocyanate, isocyanate, isothiocyanate or nitrate, or suitable metal salts preferably have a composition according to the general formula (VI) on,

M _r (X)3 (VI), where

M is selected from the metal cations Fe ³⁺ , Al ³⁺ , Co ³⁺ and Cr ³ ,

X comprises one or more (ie different) anions, preferably an anion selected from the group consisting of halides (ie fluoride, chloride, bromide, iodide), hydroxide, sulfate, carbonate, cyanate, thiocyanate, isocyanate, isothiocyanate, carboxylate, oxalate and nitrate; r is 2 when X = sulfate, carbonate or oxalate and r is 1 when X = halide, hydroxide, carboxylate, cyanate, thiocyanate, isocyanate, isothiocyanate or nitrate, or suitable metal salts preferably have a composition according to the general formula (VII) on,

M(X) _S (VII), where

M is selected from the metal cations Mo ⁴⁺ , V ⁴⁺ and W ⁴⁺ ,

X comprises one or more (i.e. different) anions, preferably an anion selected from the group consisting of halides (i.e. fluoride, chloride, bromide, iodide), hydroxide, sulfate, carbonate, cyanate, thiocyanate, isocyanate, isothiocyanate, carboxylate, oxalate and nitrate ; s is 2 when X = sulfate, carbonate or oxalate and s is 4 when X = halide, hydroxide, carboxylate, cyanate, thiocyanate, isocyanate, isothiocyanate or nitrate, or suitable metal salts preferably have a composition according to the general formula (VIII) on,

M(X) _t (VIII), where

M is selected from the metal cations Mo ⁶⁺ and W ⁶⁺ ,

X comprises one or more (i.e. different) anions, preferably anions selected from the group consisting of halides (i.e. fluoride, chloride, bromide, iodide), hydroxide, sulfate, carbonate, cyanate, thiocyanate, isocyanate, isothiocyanate, carboxylate, oxalate and nitrate; t is 3 when X = sulfate, carbonate or oxalate and t is 6 when X = halide, hydroxide, carboxylate, cyanate, thiocyanate, isocyanate, isothiocyanate or nitrate.

Examples of suitable metal salts are zinc chloride, zinc bromide, zinc iodide, zinc acetate, zinc acetylacetonate, zinc benzoate, zinc nitrate, iron(II) sulfate, iron(II) bromide, iron(II) chloride, iron(III) chloride, cobalt(II) chloride, cobalt(II) thiocyanate, nickel(II) chloride and nickel(II) nitrate. Mixtures of different metal salts can also be used.

Metal cyanide salts suitable for preparing the double metal cyanide compounds preferably have a composition according to the general formula (IX).

(Y)a M'(CN) _b (A) _c (ix), where

M' is selected from one or more metal cations from the group consisting of Fe(II), Fe(III), Co(II), Co(III), Cr(II), Cr(III), Mn(II), Mn( III), Ir(III), Ni(II), Rh(III), Ru(II), V(IV) and V(V), M' is preferably one or more metal cations from the group consisting of Co(II), Co(III), Fe(II), Fe(III), Cr(III), Ir(III) and Ni(II),

Y is selected from one or more metal cations from the group consisting of alkali metal (ie Li ⁺ , Na ⁺ , K ⁺ , Rb ⁺ ) and alkaline earth metal (ie Be ²⁺ , Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ ),

A is selected from one or more anions from the group consisting of halides (ie fluoride, chloride, bromide, iodide), hydroxide, sulfate, carbonate, cyanate, thiocyanate, isocyanate, isothiocyanate, carboxylate, azide, oxalate or nitrate and a, b and c are integers, the values for a, b and c being chosen such that the metal cyanide salt is electroneutral; a is preferably 1, 2, 3 or 4; b is preferably 4, 5 or 6; c preferably has the value 0.

Examples of suitable metal cyanide salts are sodium hexacyanocobaltate(III), potassium hexacyanocobaltate(III), potassium hexacyanoferrate(II), potassium hexacyanoferrate(III), calcium hexacyanocobaltate(III) and lithium hexacyanocobaltate(III).

Preferred double metal cyanide compounds which are contained in the DMC catalysts which can be used according to the invention are compounds having compositions according to the general formula (IX)

M _x [M' _x ,(CN) _y ] _z (IX) wherein M is as defined in formulas (V) to (VIII) and M' is as defined in formula (IX), and x, x', y and z are integers and chosen so that the electron neutrality of the double metal cyanide compound is given.

Preferably x = 3, x' = 1, y = 6 and z = 2,

M = Zn(II), Fe(II), Co(II) or Ni(II) and M' = Co(III), Fe(III), Cr(III) or Ir(III).

Examples of suitable double metal cyanide compounds a) are zinc hexacyanocobaltate(III), zinc hexacyanoiridate(III), zinc hexacyanoferrate(III) and cobalt(II) hexacyanocobaltate(III). Further examples of suitable double metal cyanide compounds can be found, for example, in US 5,158,922 (column 8, lines 29-66). Zinc hexacyanocobaltate(III) can be used with particular preference.

The organic complex ligands that can be added in the preparation of the DMC catalysts are described, for example, in US Pat. No. 5,158,922 (see in particular column 6, lines 9 to 65), US Pat 700 949, EP-A 761 708, JP 4 145 123, US 5 470 813, EP-A 743 093 and WO-A 97/40086). For example, as organic complex ligands water-soluble organic compounds containing heteroatoms, such as oxygen, nitrogen, phosphorus or sulfur, which can form complexes with the double metal cyanide compound. Preferred organic complex ligands are alcohols, aldehydes, ketones, ethers, esters, amides, ureas, nitriles, sulfides and mixtures thereof. Particularly preferred organic complex ligands are aliphatic ethers (such as dimethoxyethane), water-soluble aliphatic alcohols (such as ethanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, 2-methyl-3-buten-2-ol and 2-methyl-3-butyn-2-ol), compounds containing both aliphatic or cycloaliphatic ether groups and aliphatic hydroxyl groups (such as ethylene glycol mono-tert-butyl ether, diethylene glycol mono-tert-butyl ether, tripropylene glycol mono-methyl ether and 3-methyl-3-oxetane-methanol). Highly preferred organic complex ligands are selected from one or more compounds from the group consisting of dimethoxyethane, tert-butanol, 2-methyl-3-buten-2-ol, 2-methyl-3-butyn-2-ol, ethylene glycol mono-tert- butyl ether and 3-methyl-3-oxetane-methanol.

In the preparation of the DMC catalysts that can be used according to the invention, one or more complex-forming component(s) from the compound classes of polyethers, polyesters, polycarbonates, polyalkylene glycol sorbitan esters, polyalkylene glycol glycidyl ethers, polyacrylamide, poly(acrylamide-co-acrylic acid), polyacrylic acid, poly(acrylic acid co-maleic acid), polyacrylonitrile, polyalkyl acrylates, polyalkyl methacrylates, polyvinyl methyl ether, polyvinyl ethyl ether, polyvinyl acetate, polyvinyl alcohol, poly-N-vinylpyrrolidone, poly(N-vinylpyrrolidone-co-acrylic acid), polyvinyl methyl ketone, poly(4-vinylphenol), poly(acrylic acid-co -styrene), oxazoline polymers, poly alkylenimines, maleic acid and maleic anhydride copolymers, hydroxyethyl cellulose and poly acetals, or glycidyl ethers, glycosides, carboxylic acid esters of polyhydric alcohols, bile acids or their salts, esters or amides, cyclodextrins, phosphorus compounds, a,b-unsaturated carboxylic acid esters or ionic Surface or interfacial act ive connections used.

When preparing the DMC catalysts that can be used according to the invention, preference is given to using the aqueous solutions of the metal salt (e.g. zinc chloride) in the first step in a stoichiometric excess (at least 50 mol %), based on the metal cyanide salt. This corresponds to at least a molar ratio of metal salt to metal cyanide salt of 2.25 to 1.00. The metal cyanide salt (e.g. potassium hexacyanocobaltate) is reacted in the presence of the organic complex ligand (e.g. tert-butanol) to form a suspension containing the double metal cyanide compound (e.g. zinc hexacyanocobaltate), water, excess metal salt, and the organic complex ligand.

The organic complex ligand can be present in the aqueous solution of the metal salt and/or the metal cyanide salt, or it is added directly to the suspension obtained after precipitation of the double metal cyanide compound. It has proven advantageous to mix the aqueous solutions of the metal salt and the metal cyanide salt and the organic complex ligand with vigorous stirring. The one formed in the first step is optional Suspension then treated with another complex-forming component. The complex-forming component is preferably used in a mixture with water and organic complex ligands. A preferred method for carrying out the first step (ie the preparation of the suspension) is carried out using a mixing nozzle, particularly preferably using a jet disperser, as described, for example, in WO-A 01/39883.

In the second step, the solid (i.e. the precursor of the catalyst) can be isolated from the suspension by known techniques such as centrifugation or filtration. In a preferred embodiment, the isolated solid is then washed with an aqueous solution of the organic complex ligand in a third process step (e.g. by resuspending and subsequent renewed isolation by filtration or centrifugation). In this way, for example, water-soluble by-products such as potassium chloride can be removed from the catalyst that can be used according to the invention. The amount of the organic complex ligand in the aqueous washing solution is preferably between 40 and 80% by weight, based on the total solution.

Optionally, in the third step, a further complex-forming component, preferably in the range between 0.5 and 5% by weight, based on the total solution, is added to the aqueous washing solution.

In addition, it is advantageous to wash the isolated solid more than once. Preferably, in a first washing step (3.-1), washing is carried out with an aqueous solution of the unsaturated alcohol (e.g. by resuspending and then isolating again by filtration or centrifugation) in order in this way, for example, to remove water-soluble by-products, such as potassium chloride, from the to remove catalyst. The amount of unsaturated alcohol in the aqueous washing solution is particularly preferably between 40 and 80% by weight, based on the total solution of the first washing step. In the further washing steps (3.-2), the first washing step is carried out either once or several times, preferably once to three times repeated, or preferably a non-aqueous solution, such as a mixture or solution of unsaturated alcohol and other complex-forming component (preferably in the range between 0.5 and 5% by weight, based on the total amount of the washing solution of step (3.- 2)), used as washing solution and the solid washed with it once or several times, preferably once to three times.

The isolated and optionally washed solid can then, optionally after pulverization, be dried at reactor temperatures of 20-100° C. and at pressures of 0.1 mbar to atmospheric pressure (1013 mbar). A preferred process for isolating the DMC catalysts which can be used according to the invention from the suspension by filtration, filter cake washing and drying is described in WO-A 01/80994.

The double metal cyanide (DMC) catalyst is preferably used in a calculated amount of 100 to 3000 ppm, preferably 120 to 2500 ppm, particularly preferably 150 to 2200 ppm, based on the sum of the masses of the polymeric formaldehyde compound and the alkylene oxide. If the proportion of DMC catalyst is high, the heavy metals must be removed before further conversion to form the polyurethane. Below 100 ppm of the double metal cyanide (DMC) catalyst, catalytic conversion can no longer be observed.

In the process according to the invention, suspension agents with H-functional groups or suspension agents without H-functional groups, preferably suspension agents without H-functional groups, are used.

In the process according to the invention, a suspending agent is placed in a reactor.

In one embodiment of the process according to the invention, the suspending agent in step (a) contains no H-functional groups.

In step (a), a suspending agent which contains no H-functional groups is preferably initially taken in the reactor together with the DMC catalyst, and no polymeric formaldehyde compound is initially taken in the reactor. Alternatively, in step (a), a suspending agent which contains no H-functional groups and, in addition, a portion of the polymeric formaldehyde compound and, if appropriate, DMC catalyst can be initially taken in the reactor.

In a preferred embodiment, an inert gas (for example argon or nitrogen), an inert gas Carbon dioxide mixture or carbon dioxide introduced and at the same time a reduced pressure (absolute) from 10 mbar to 800 mbar, particularly preferably from 50 mbar to 200 mbar applied.

In an alternative preferred embodiment, the resulting mixture of suspending agent and DMC catalyst is at a temperature of 50 to 120° C., preferably 60 to 110° C. and particularly preferably 70 to 100° C., at least once, preferably three times, at 1.5 bar to 10 bar (absolute), particularly preferably 3 bar to 6 bar (absolute) of an inert gas (e.g. argon or nitrogen), an inert gas-carbon dioxide mixture or carbon dioxide and the overpressure is then reduced to about 1 bar (absolute). The DMC catalyst can be added in solid form or as a suspension in a suspending agent or in a mixture of at least two suspending agents. In a further preferred embodiment, in step (a)

(a-1) the suspending agent or a mixture of at least two suspending agents and

(a-11) bringing the temperature (reactor temperature) of the suspension medium or the mixture of at least two suspension mediums to 50 to 120° C., preferably from 60 to 110° C. and particularly preferably from 70 to 100° C., and/or the pressure in the reactor less than 500 mbar, preferably 5 mbar to 100 mbar, with an inert gas stream (e.g. of argon or nitrogen), an inert gas-carbon dioxide stream or a carbon dioxide stream being passed through the reactor, where appropriate, the double metal cyanide catalyst for Suspending agents or the mixture of at least two suspending agents are added in step (a-1) or immediately thereafter in step (a-11), and wherein the suspending agent does not contain any H-functional groups.

Step (ß) serves to activate the DMC catalyst. If appropriate, this step can be carried out under an inert gas atmosphere, under an atmosphere of an inert gas/carbon dioxide mixture or under a carbon dioxide atmosphere. For the purposes of this invention, activation is a step in which a portion of the alkylene oxide compound is added at temperatures (reactor temperatures) of from 50 to 120° C., preferably from 55 to 110° C. and particularly preferably from 60 to 100° C., to form the DMC catalyst suspension ( Mixture from step (a)) is added and then the addition of the alkylene oxide compound is interrupted, with heat being generated as a result of a subsequent exothermic chemical reaction, which can lead to a temperature peak in the reaction system ("hotspot"), as well as due to the reaction of alkylene oxide and possibly CO2 a pressure drop in the reactor is observed. The process step of activation is the period of time from the addition of the partial amount of alkylene oxide compound, optionally in the presence of CO 2 , to the DMC catalyst until heat is generated. If appropriate, the partial amount of alkylene oxide compound can be added to the DMC catalyst in several individual steps, if appropriate in the presence of CO2, and then the addition of the alkylene oxide compound can be interrupted in each case. In this case, the process step of activation comprises the period of time from the addition of the first portion of alkylene oxide compound, optionally in the presence of CO2, to the DMC catalyst until the occurrence of heat generation after addition of the last portion of alkylene oxide compound. In general, the activation step can be followed by a step for drying the DMC catalyst and if appropriate, upstream of the polymeric formaldehyde compound at elevated temperature (reactor temperature) and/or reduced pressure, if appropriate with passing an inert gas through the reaction mixture.

In principle, one or more alkylene oxides (and optionally the carbon dioxide) can be metered in in different ways. Dosing can be started from the vacuum or with a previously selected pre-pressure. The admission pressure is preferably set by introducing an inert gas (such as nitrogen or argon) or carbon dioxide, the pressure (absolute) being 5 mbar to 100 bar, preferably 10 mbar to 50 bar and preferably 20 mbar to 50 bar. In a preferred embodiment, the amount of one or more alkylene oxides used in the activation in step (β) is 0.1 to 25.0% by weight, preferably 1.0 to 20.0% by weight, particularly preferably 2. 0 to 16.0% by weight (based on the amount of suspending agent used in step (a)). The alkylene oxide can be added in one step or in portions in several portions. After the addition of a portion of the alkylene oxide compound, the addition of the alkylene oxide compound is preferably interrupted until heat is generated and only then is the next portion of the alkylene oxide compound added. In one embodiment of the process according to the invention, the polymeric formaldehyde compound and/or the alkylene oxide is metered into the reactor stepwise or continuously in step (g). In a preferred embodiment of the process according to the invention, the polymeric formaldehyde compound and the alkylene oxide are continuously metered into the reactor in step (g). dosed. In a preferred embodiment of the process according to the invention, the polymeric formaldehyde compound and the alkylene oxide are metered in continuously in step (g).

One or more polymeric formaldehyde compound(s), one or more alkylene oxide(s) and optionally also the carbon dioxide can be metered in simultaneously or sequentially (in portions), for example the total amount of carbon dioxide, the amount of polymeric formaldehyde compound and/or that in step ( g) metered amounts of alkylene oxides are added all at once or continuously. As used herein, the term "continuously" can be defined as a mode of addition of a reactant such that a copolymerization-effective concentration of the reactant is maintained, ie, for example, dosing can be at a constant dosing rate, at a varying dosing rate, or incrementally. It is possible during the addition of the alkylene oxide and/or the polymeric formaldehyde compound to gradually or stepwise increase or decrease the CCF pressure or leave it the same. The total pressure is preferably kept constant during the reaction by adding more carbon dioxide. One or more alkylene oxide(s) and/or the one or more polymeric formaldehyde compound(s) are metered in simultaneously or sequentially with the carbon dioxide metering. It is possible to meter in the alkylene oxide at a constant metering rate, or to increase or decrease the metering rate gradually or stepwise, or to add the alkylene oxide in portions. The alkylene oxide is preferably added to the reaction mixture at a constant metering rate. If several alkylene oxides are used to synthesize the polyoxymethylene-polyoxyalkylene copolymers, the alkylene oxides can be metered in individually or as a mixture. The alkylene oxides or the polymeric formaldehyde compound can be metered in simultaneously or sequentially via separate meterings (additions) or in one or more meterings, it being possible for the alkylene oxides or the polymeric formaldehyde compounds to be metered in individually or as a mixture. It is possible to synthesize statistical, alternating, block-like or gradient-like polyoxymethylene-polyoxyalkylene copolymers via the type and/or order of metering of the polymeric formaldehyde compounds, the alkylene oxides and/or the carbon dioxide. In a preferred embodiment, in step (g) the metering of the one or more polymeric formaldehyde compound(s) is ended before the addition of the alkylene oxide. In a further embodiment of the process according to the invention, an excess of carbon dioxide is used, based on the calculated amount of carbon dioxide incorporated in the polyethercarbonate polyol, since an excess of carbon dioxide is advantageous due to the inertness of carbon dioxide. The amount of carbon dioxide can be determined via the total pressure under the particular reaction conditions. The range from 0.01 to 120 bar, preferably from 0.1 to 110 bar, particularly preferably from 1 to 100 bar, has proven advantageous as the total pressure (absolute) for the copolymerization to prepare the polyethercarbonate polyols. It is possible to supply the carbon dioxide continuously or discontinuously. This depends on how quickly the alkylene oxides are consumed and whether the product is supposed to contain CCF-free polyether blocks. The amount of carbon dioxide (expressed as pressure) can also vary when adding the alkylene oxides. CO2 can also be added to the reactor as a solid and then, under the selected reaction conditions, convert to the gaseous, dissolved, liquid and/or supercritical state.

A preferred embodiment of the method according to the invention is characterized, inter alia, in that in step (g) the total amount of the one or more polymers Formaldehyde compound (s) is added. This addition can be done at a constant metering rate, at a varying metering rate or in portions. In one embodiment of the process according to the invention, step (g), ie the copolymerization of the polymeric formaldehyde compound with the alkylene oxide, takes place at a reactor temperature of 73.degree. C. to 83.degree. preferably from 75°C to 82°C.

The reactor temperature in the present invention is defined as a predetermined temperature and does not take into account any temperature increases or decreases in the reaction system, for example, due to exo- or endothermic reactions.

For the process according to the invention it has also been shown that the copolymerization in the presence of carbon dioxide (step (g)) for the preparation of the polyoxymethylene polyether carbonate polyol copolymers or the polymerization in the presence of an inert gas such as nitrogen to form polyoxymethylene polyether polyol copolymers advantageously i.e. step (g) at a reactor temperature of from 73°C to 83°C. preferably from 75°C to from 82°C.

The alkylene oxide, the polymeric formaldehyde compound and the DMC catalyst can be metered in via separate or common metering points. In a preferred embodiment, the alkylene oxide and the polymeric formaldehyde compound are fed continuously to the reaction mixture via separate metering points. This addition of the one or more polymeric formaldehyde compound(s) can take place as continuous metering into the reactor or in portions.

Steps (a), (β) and (g) can be carried out in the same reactor or each separately in different reactors. Particularly preferred reactor types are: tubular reactors, stirred tanks, loop reactors.

Polyoxymethylene-polyoxyalkylene copolymers can be prepared in a stirred tank, the stirred tank being cooled, depending on the embodiment and mode of operation, via the reactor jacket, internal cooling surfaces and/or cooling surfaces located in a pumped circuit. Both in the semi-batch application, in which the product is removed only after the end of the reaction, and in the continuous application, in which the product is removed continuously, particular attention must be paid to the metering rate of the alkylene oxide. It is to be set in such a way that, despite the inhibiting effect of the carbon dioxide and/or the polymeric formaldehyde compound, the alkylene oxides react sufficiently quickly. The concentration of free alkylene oxides in the reaction mixture during the activation step (step ß) is preferably >0 to 100% by weight, more preferably >0 to 50% by weight, most preferably >0 to 20% by weight (each based on the weight of the reaction mixture). The concentration of free Alkylene oxides in the reaction mixture during the reaction (step g) is preferably >0 to 40% by weight, more preferably >0 to 25% by weight, most preferably >0 to 20% by weight, based in each case on the weight of the reaction mixture. In a preferred embodiment, the activated DMC catalyst-suspending agent mixture resulting from steps (a) and (β) is further reacted in the same reactor with one or more alkylene oxide(s), one or more polymeric formaldehyde compound(s) and optionally carbon dioxide In a further preferred embodiment, according to steps (a) and (ß) resulting activated DMC catalyst-suspending agent mixture in another reaction vessel (e.g. a stirred tank, tubular reactor or loop meactor) further with alkylene oxides, one or more polymeric formaldehyde compound (s ) and optionally carbon dioxide.

When the reaction is carried out in a tubular reactor, the activated catalyst-suspending agent mixture resulting from steps (a) and (ß), one or more polymeric formaldehyde compound(s), one or more alkylene oxide(s) and optionally carbon dioxide are pumped continuously through a tube. The molar ratios of the reactants vary depending on the desired polymer. In a preferred embodiment, carbon dioxide is metered in in its liquid or supercritical form in order to enable optimum miscibility of the components. Advantageously, mixing elements are installed for better mixing of the reactants, such as those sold by Ehrfeld Mikrotechnik BTS GmbH, for example, or mixer-heat exchanger elements, which at the same time improve mixing and heat dissipation.

Loop meactors can also be used to make polyoxymethylene-polyoxyalkylene copolymers. These generally include reactors with material recycling, such as a jet loop reactor, which can also be operated continuously, or a loop-shaped tubular reactor with suitable devices for circulating the reaction mixture, or a loop of a plurality of tubular reactors connected in series. The use of a loop meactor is particularly advantageous because backmixing can be implemented here, so that the concentration of free alkylene oxides in the reaction mixture is in the optimum range, preferably in the range >0 to 40% by weight, particularly preferably >0 to 25% by weight % by weight, most preferably >0 to 16% by weight (in each case based on the weight of the reaction mixture).

The polyoxymethylene-polyoxyalkylene copolymers are preferably produced in a continuous process which comprises both continuous copolymerization and continuous addition of the one or more polymeric formaldehyde compound(s). In a further embodiment of the process according to the invention, the resulting reaction mixture is continuously removed from the reactor in step (g).

The invention therefore also relates to a process in which, in step (g), one or more polymeric formaldehyde compound(s), one or more alkylene oxide(s) and DMC catalyst are metered continuously into the reactor, optionally in the presence of carbon dioxide (“copolymerization”) and wherein the resulting reaction mixture (containing the reaction product) is continuously removed from the reactor.

For example, an activated DMC catalyst-suspending agent mixture is prepared for the continuous process for preparing the polyoxymethylene-polyoxyalkylene copolymers according to steps (a) and (ß), then according to step (g)

(gΐ) in each case a subset of one or more polymeric formaldehyde compound(s), one or more alkylene oxide(s) and optionally carbon dioxide metered in to initiate the copolymerization, and

(g2) continuously metering in the remaining amount of DMC catalyst, one or more polymeric formaldehyde compound(s) and alkylene oxide(s), optionally in the presence of carbon dioxide, while the copolymerization is progressing, the resulting reaction mixture being simultaneously removed continuously from the reactor. In step (g), the DMC catalyst is preferably added suspended in the suspension medium with H-functional groups or suspension medium without H-functional groups, preferably suspension medium without H-functional groups, the amount preferably being chosen such that the content of DMC catalyst in the resulting reaction product is 10 to 10000 ppm, more preferably 20 to 5000 ppm and most preferably 50 to 800 ppm. In one embodiment of the process according to the invention, the double metal cyanide (DMC) catalyst is used in a theoretical amount of 50 to 800 ppm, based on the sum of the masses of the polymeric formaldehyde compound and the alkylene oxide.

Preferably, steps (a) and (β) are carried out in a first reactor and the resulting reaction mixture is then transferred to a second reactor for the copolymerization of step (g). However, it is also possible to carry out steps (a), (β) and (g) in one reactor.

It has also been found that the process of the present invention can be used to produce large quantities of the polyoxymethylene-polyoxyalkylene copolymer product initially using a DMC activated according to steps (a) and (ß) in a suspending agent. Catalyst is used, and during the copolymerization (g) the DMC catalyst is added without prior activation.

Thus, a particularly advantageous feature of the preferred embodiment of the present invention is the ability to use "fresh" DMC catalysts without activation for the portion of DMC catalyst that is continuously added in step (g). Activation of DMC catalysts to be performed analogously to step (β) not only involves additional operator attention, which increases manufacturing costs, but also requires a pressure reaction vessel, which also increases capital costs in building a corresponding production plant. Here, "fresh" catalyst is defined as unactivated DMC catalyst in solid form or in the form of a slurry in a polymeric formaldehyde compound or suspending agent. The ability of the present process to use fresh, unactivated DMC catalyst in step (g) allows for significant savings in the commercial production of polyethercarbonate polyols and is a preferred embodiment of the present invention.

As used herein, the term "continuously" can be defined as a mode of addition of a relevant catalyst or reactant such that a substantially continuous effective concentration of the DMC catalyst or reactant is maintained. The catalyst feed can be truly continuous or in relatively closely spaced increments. Likewise, continuous addition of the polymeric formaldehyde compound can be truly continuous or it can be incremental. It would not deviate from the present method to incrementally add a DMC catalyst or reactants such that the concentration of the added materials falls to essentially zero for some time before the next incremental addition. However, it is preferred that the DMC catalyst concentration be maintained at substantially the same concentration during most of the course of the continuous reaction and that starter substance be present during most of the copolymerization process. Incremental addition of DMC catalyst and/or reactant that does not substantially affect the nature of the product is still "continuous" as the term is used herein. For example, it is feasible to provide a recycle loop in which a portion of the reacting mixture is recycled to a previous point in the process, thereby smoothing out discontinuities caused by incremental additions.

Optionally, in step (d), the reaction mixture removed continuously in step (g), which generally contains from 0.05% by weight to 10% by weight of alkylene oxide, can be transferred to an after-reactor in which a post-reaction the content of free Alkylene oxide is reduced to less than 0.05% by weight in the reaction mixture. A tubular reactor, a loop reactor or a stirred tank, for example, can be used as the after-reactor.

The pressure in this after-reactor is preferably the same as in the reaction apparatus in which reaction step (g) is carried out. However, the pressure in the downstream reactor can also be selected to be higher or lower. In a further preferred embodiment, the carbon dioxide is released completely or partially after reaction step (g) and the downstream reactor is operated at atmospheric pressure or a slight excess pressure. The temperature (reactor temperature) in the downstream reactor is preferably 50 to 150°C and particularly preferably 80 to 140°C.

Another object of the present invention are polyoxymethylene-polyoxyalkylene copolymers obtainable by the process according to the invention. In one embodiment of the invention, the polyoxymethylene-polyalkylene oxide copolymer has an oxymethylene group content of 1% by weight to 70% by weight, preferably 10% by weight to 50% by weight and particularly preferably 20% by weight. up to 50% by weight, based on the polyoxymethylene-polyalkylene oxide copolymer product, and determined using the 1H-NMR method described in the experimental section. In one embodiment, the polyoxymethylene copolymers have a number-average molecular weight of <15000 g/mol, preferably <9500 g/mol, particularly preferably <6000 g/mol, very particularly preferably <5000 g/mol, in particular from 200 g/mol to 9500 g/mol, preferably from 500 g/mol to 5000 g/mol. The number-average molecular weight can be determined, for example, by gel permeation chromatography (GPC) against e.g. polystyrene standards and/or via experimentally determined hydroxyl numbers (OH#). In a preferred embodiment, the polyoxymethylene copolymers have a number-average molecular weight of from 500 g/mol to 5000 g/mol, preferably from 1000 g/mol to 4000 g/mol and particularly preferably from 1500 g/mol to 3500 g/mol. The number-average molecular weight can be determined, for example, by gel permeation chromatography (GPC) against e.g. polystyrene standards and/or via experimentally determined hydroxyl numbers (OH#).

The polyoxymethylene copolymers of the invention preferably have terminal hydroxy groups and preferably have a hydroxy functionality F > 2 (number of hydroxy groups per molecule). In a further embodiment of the polyoxymethylene copolymers, they have a monomodal molecular weight distribution and a polydispersity index (PD1) of <2.5, preferably <2.2. The polyoxymethylene copolymers obtainable by the process according to the invention preferably contain less than 1.0% by weight, in particular less than 0.5% by weight, based on the total mass of the polyoxymethylene copolymer obtained, of formate and/or methoxy impurities. The polyoxymethylene copolymers obtainable by the process according to the invention generally have a low content of by-products and decomposition products, such as formate, traces of methoxy, monomeric and oligomeric formaldehyde, residual monomers and can be processed without problems, in particular by reaction with di-, tri- and /or polyisocyanates to form polyurethanes, isocyanate-functionalized polyurethane prepolymers or polyisocyanurates, in particular polyurethane thermoplastics, polyurethane coatings,

Fibers, elastomers, adhesives and, in particular, polyurethane foams, including flexible (such as, for example, flexible polyurethane block foams and flexible polyurethane molded foams) and rigid foams. Polyoxymethylene copolymers which have a functionality of at least 2 are preferably used for polyurethane applications. Furthermore, the polyoxymethylene copolymers obtainable by the process according to the invention can be used in applications such as detergent and cleaning agent formulations, adhesives, paints, varnishes, functional fluids, drilling fluids, fuel additives, ionic and non-ionic surfactants, lubricants, process chemicals for paper or textile production or cosmetic/ medicinal formulations are used. The person skilled in the art knows that, depending on the respective area of application, the polymers to be used must meet certain material properties such as molecular weight, viscosity, polydispersity, functionality and/or hydroxyl number (number of terminal hydroxyl groups per molecule).

The invention further relates to a method for producing a polyurethane polymer, comprising the step of reacting a polyisocyanate component with a polyol component, the polyol component comprising the polyoxymethylene-polyoxyalkylene copolymer obtained by the method according to the invention. In one embodiment of this method, the polyurethane polymers are flexible polyurethane foams or rigid polyurethane foams. In a further embodiment of this method, the polyurethane polymers are thermoplastic polyurethane polymers.

The subject matter of the invention is therefore also a polyurethane polymer obtainable by reacting a di-, tri- and/or polyisocyanate with at least one polyoxymethylene-polyoxyalkylene copolymer obtained by the process according to the invention.

The invention also relates to a flexible polyurethane foam or a rigid polyurethane foam obtainable by reacting a di-, tri- and/or polyisocyanate with at least one polyoxymethylene-polyoxyalkylene copolymer obtained by the process according to the invention. Also included according to the invention is the use of polyoxymethylene-polyoxyalkylene copolymer obtained by the process according to the invention for the production of polyurethanes, detergent and cleaning agent formulations, drilling fluids, fuel additives, ionic and nonionic surfactants, lubricants, process chemicals for paper or textile production or cosmetic formulations .

examples

Used connections:

Paraformaldehyde (Granuform M®) from Prefere Paraform GmbH & Co. KG was used. Propylene oxide (PO) was purchased from Sigma-Aldrich and used without purification. In all examples, DMC catalyst was prepared as DMC catalyst according to example 6 in WO 01/80994 A1, containing zinc hexacyanocobaltate, tert. -Butanol and polypropylene glycol with a number-average molecular weight of 1000 g/mol.

method description

'H NMR

The composition of the polymer was determined by means of 111-NMR (Bruker, DPX 400, 400 MHz; pulse program ^zg30 , waiting time D1: 10 s, 64 scans). Each sample was dissolved in deuterated chloroform. The relevant resonances in the ¹ 11-NMR (based on TMS = 0 ppm) and the assignment of the area integrals (A) are as follows:

• cyclic propylene carbonate (cPC), by-product, resonating at 4.5 ppm, area integral corresponds to an H atom;

• monomeric propylene oxide (PO), which is not reacted, with resonance at 2.4 or 2.75 ppm, area integral corresponds to an H atom in each case;

• Polypropylene oxide (PPO), PO homopolymer, with resonances at 1.0 to 1.2 ppm, area integral corresponds to 3 H atoms;

• Poly- or paraformaldehyde (pFA) with resonances at 4.6 to 5.2 ppm, area integral minus one H atom of the cyclic propylene carbonate (cPC) thus corresponds to 2 H atoms;

The mole fractions (x) of the reaction mixture are determined as follows:

• x(cPC) = A(4.5ppm)

• x(PO) = A(2.75ppm) or A(2.4ppm)

• x(PPO) = A(1.0-1.2ppm)/3

• x(pFA) = (A(4.6-5.2 ppm) - x(cPc) - x(cPC))/2 x(HCOO) = A(8.1 ppm) x(MeO) = A(3.4ppm)/3

The mole percentage is calculated by dividing the mole fraction (x) of each component by the sum of the mole fractions present in the sample. In addition, the weight fraction is calculated by multiplying the mole fractions (x) by the associated molar masses and dividing by the sum of the weight parts contained. The following molar masses (g/mol) are used to convert the parts by weight: cPC = 102, PO and PPO = 58, pFA = 30. The polymer composition is calculated and normalized using the parts PPO and pFA, so that the specification in parts by weight of 100 (wt%) is made.

Determination of functionality F

The proportion of formate determined by ¹ 11 NMR reflects the proportion of MeOH formed in the equimolar proportion (F=1). The difference between this amount of substance n(OH, F=1) and the amount of substance n(OH, theoretical) (theoretical hydroxyl value of the recipe) gives the amount of substance of the diol components n(F=2). The functionality of the product mixture is formed via the proportions of the respective molar amounts of F=2 -based hydroxyl groups and F=1 -based hydroxyl groups in relation to the total molar amount.

Gel Permeation Chromatography (GPC)

The weight and number average molecular weights Mw and Mn of the resulting polymers were determined by gel permeation chromatography (GPC). The procedure was based on DIN 55672-1: "Gel permeation chromatography, part 1 - tetrahydrofuran as

Eluent”. Polystyrene samples of known molar mass were used for calibration. The polydispersity index is calculated from the quotient of the weight-average and number-average molecular weight.

Example 1 Production of the polyoxymethylene-polyalkylene oxide copolymer with a total DMC catalyst loading of 1000 ppm and continuous addition of pFA and PO in step g 10 g of pretreated pFA (pretreatment: 50° C., 5 mbar, 1.5 h) and 300 mg DMC catalyst suspended in 150 g cPC. Inerting with N2 (25 L/h) with stirring (500 rpm) at 30 mbar is carried out at 60° C. for 30 min. The suspension was heated to 70°C with stirring (1000 rpm). After the reactor temperature had been reached, 20 g of propylene oxide (8.8% by weight) were quickly added to the suspension. The onset of the reaction was noticeable by a temperature peak (“hotspot”) combined with a simultaneous drop in pressure. The reactor temperature was then increased to 80° C., and the 208 g of PO were added at a metering rate of 0.9 g/min and 62 g of paraformaldehyde (as a 20% suspension in cPC) at a metering rate of 1.7 g/min. After the addition was complete, the mixture was stirred until the exothermic reaction subsided or the pressure remained constant at 80.degree. The product mixture was then removed and degassed on a rotary evaporator at 60° C. and 10 mbar. The reaction mixture was analyzed by means of GPC and NMR analysis.

_Mn (GPC) = 2605 g/mol PD1 = 1.19

According to NMR, a formaldehyde content in the polymer of 22.1% by weight was determined. According to NMR, the total proportion of formate and methoxy end groups was less than 0.2% by weight.

Example 2 (Comparative): Preparation of the polyoxymethylene-polyalkylene oxide copolymer with a total DMC catalyst loading of 1000 ppm and continuous addition of pFA and PO in step g

The experiment was carried out analogously to Example 1, with the continuous metering of PO and pFA being carried out at a reactor temperature of 90° C. in step g.

_Mn (GPC) = 2742 g/mol PD1 = 1.05

According to NMR, a formaldehyde content in the polymer of 21.7% by weight was determined. According to NMR, the total proportion of formate and methoxy end groups was less than 0.3% by weight.

Example 3 (Comparative): Preparation of the polyoxymethylene-polyalkylene oxide copolymer with a total DMC catalyst loading of 1000 ppm and continuous addition of pFA and PO in step g

The experiment was carried out analogously to example 1, with the continuous metering of PO and pFA being carried out at a reactor temperature of 70° C. in step g.

_Mn (GPC) = 2610 g/mol PD1 = 1.21

According to NMR, a formaldehyde content in the polymer of 22.2% by weight was determined. According to NMR, the total proportion of formate and methoxy end groups was less than 0.2% by weight.

Claims

patent claims

Claims 1. A process for preparing a polyoxymethylene-polyoxyalkylene copolymer comprising reacting a polymeric formaldehyde compound with an alkylene oxide in the presence of a double metal cyanide (DMC) catalyst; wherein the polymeric formaldehyde compound has at least one terminal hydroxyl group; the method comprising the following steps:

(a) Submission of a suspending agent in a reactor

2. The process of claim 1 wherein step (g) is carried out at a reactor temperature of from 73°C to 83°C. preferably from 75°C to 82°C.

3. The method according to claim 1 or 2, wherein in step (g) the polymeric formaldehyde compound is metered continuously or in stages, preferably continuously.

4. The method according to any one of claims 1 to 3, wherein in step (g) the alkylene oxide is metered continuously or stepwise, preferably continuously.

5. The method according to any one of claims 1 to 4, wherein in step (g) the metering of the one or more polymeric formaldehyde compound (s) is terminated before the addition of the alkylene oxide.

6. The method according to any one of claims 1 to 5, wherein in step (g) the resulting reaction mixture is continuously removed from the reactor.

7. The method according to any one of claims 1 to 6, wherein in step (g) DMC catalyst is continuously metered into the reactor and the resulting reaction mixture is continuously removed from the reactor.

8. The method according to any one of claims 1 to 7, wherein in step (a) the suspending agent does not contain any H-functional groups.

9. The method according to claim 8, wherein in step (a) a suspending agent which contains no H-functional groups is initially charged together with the DMC catalyst in the reactor.

10. The method according to claim 9, wherein subsequent to step (a)

(β) a portion of alkylene oxide is added to the mixture from step (a) at reactor temperatures of from 50 to 120° C., and the addition of the alkylene oxide compound is then interrupted.

11. The method according to any one of claims 8 to 10, wherein in step (a) the suspending agent that contains no H-functional groups is one or more compound(s) and is selected from the group consisting of 4-methyl-2-oxo -l,3-dioxolane, 1,3-dioxolan-2-one, acetone, methyl ethyl ketone, acetonitrile, nitromethane, dimethyl sulfoxide, sulfolane, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, dioxane, diethyl ether, methyl tert-butyl ether, tetrahydrofuran, ethyl acetate , butyl acetate, pentane, n-

hexane, benzene, toluene, xylene, ethylbenzene, chloroform, chlorobenzene, dichlorobenzene and carbon tetrachloride.

12. The method according to any one of claims 1 to 11, wherein the alkylene oxide is one or more compound (s) and is selected from the group consisting of ethylene oxide, propylene oxide, styrene oxide and cyclohexene oxide, preferably ethylene oxide and propylene oxide and particularly preferably propylene oxide.

13. The method according to any one of claims 1 to 12, wherein the polymeric formaldehyde compound has 2 hydroxyl groups and 8 to 100 oxymethylene repeating units (s) or 3 hydroxyl groups and 8 to 100 oxymethylene repeating units (s).

14. The method according to any one of claims 1 to 13, wherein the double metal cyanide (DMC) - catalyst is used in a theoretical amount of 50 to 800 ppm based on the sum of the masses of the polymeric formaldehyde compound and the alkylene oxide.

15. A process for preparing a polyurethane polymer, comprising the step of reacting a polyisocyanate component with a polyol component, wherein the

The polyol component comprises a polyoxymethylene-polyoxyalkylene copolymer obtained according to the process of any one of claims 1 to 14.