EP3790919A1

EP3790919A1 - Separating a double metal cyanide catalyst

Info

Publication number: EP3790919A1
Application number: EP19720923.2A
Authority: EP
Inventors: Thomas Ernst MÜLLER; Michael Pohl
Original assignee: Covestro Intellectual Property GmbH and Co KG
Current assignee: Covestro Intellectual Property GmbH and Co KG
Priority date: 2018-05-08
Filing date: 2019-05-06
Publication date: 2021-03-17
Also published as: EP3567067A1; WO2019215103A1; US20210363298A1; CN112384550A

Abstract

The invention relates to a method for separating a double metal cyanide catalyst (DMC catalyst) from polyol, comprising the steps of: A) providing in a reactor: a polyol containing the DMC catalyst; an alcohol; and optionally a filtering aid, the mixture being heated, B) filtering the mixture from step A), C) optionally separating the alcohol from the filtrate of step B), characterized in that in step A) 4 wt.% to 12 wt.% ethanol, in reference to 100 wt.% polyol, is used as the alcohol, without a chelating agent.

Description

Separation of double metal cyanide catalyst

This invention relates to a process for the separation of a double metal cyanide catalyst (hereinafter also called DMC catalyst) from polyols.

DMC catalysts are used in the preparation of polyols, such as polyether polyols or polyether carbonate polyols. These catalysts have a high efficiency in the polymerization, whereby the proportion of Kata analyzer used can be kept low. Despite the low proportion of DMC catalyst in the polyol, the storage stability of CCh-containing polyols is reduced by residues of active DMC catalyst in the polyol. For this reason, as well as due to the composition of the metal compound DMC catalyst such as cobalt compounds, separation is desirable.

A common method for separating the DMC catalyst from the polyol is the Filtrati on, in an upstream step, the DMC catalyst is converted into an insoluble to stand. The patent US 5,416,241 discloses for this upstream step the use of alkali metal hydroxides, water and magnesium silicate. No. 5,099,075 describes the separation of the DMC catalyst by its oxidation with, for example, hydrogen peroxide and subsequent filtration. In US 5,248,833, an alcohol is used in combination with an acidic chelating agent to subsequently filter the DMC catalyst. The use of such reactive compounds is undesirable from a safety, environmental and economical point of view and may also have negative effects on the polyol. For example, the use of alkali metal salts in polyether carbonate polyols can lead to the cleavage of the carbonate group in the polyethercarbonate polyol and thus broaden the molecular weight distribution of the polyethercarbonate polyol. In EP 0 385 619 A2, the DMC catalyst is rendered insoluble by the addition of a nonpolar solvent, and then filtered. However, in EP 0 385 619 A2, at least 50% by weight, based on the polyol, of a non-polar solvent is used. However, the use and subsequent separation of these amounts of solvents is uneconomical. The object of the present invention is therefore to provide an economical process for the separation of a DMC catalyst without the use of a chelating agent, which leads to no or only insignificant changes to the polyol.

Surprisingly, this object has been achieved by a process for the separation of a double metal cyanide (DMC) catalyst from polyol, comprising the steps

A) introducing a polyol containing DMC catalyst, an alcohol and, if appropriate, a filter aid into a reactor, the mixture being heated, B) filtering the mixture from step A),

C) optionally separating the alcohol from the filtrate of step B), characterized in that used in step A) as the alcohol 4 wt .-% to 12 wt .-% ethanol, based on 100 wt .-% polyol, without a chelating agent become. In the following, the steps carried out in the method according to the invention are described in more detail.

Step A)

The polyol containing DMC catalyst is a polyether polyol, polyetherester polyol, polyether carbonate polyol or a mixture of the aforementioned compounds. The polyol is preferably a polyethercarbonate polyol.

Polyether carbonate polyols are prepared by addition of alkylene oxide and carbon dioxide to an H-functional initiator compound in the presence of a DMC catalyst, preferably by the steps:

(A) submitting a subset of the H-functional starter compounds and / or suspending agent, which contains no H-functional groups, in a reactor each together with DMC catalyst and optionally removing water and / or other volatile compounds by elevated temperature and / or reduced pressure ("drying"), (β) activation of the DMC catalyst by adding a portion (based on the total amount of alkylene oxide used in the activation and copolymerization) of alkylene oxide to the mixture resulting from step (a), wherein this addition of a partial amount of alkylene oxide, optionally in the presence C0 ₂ can take place, and in which case the temperature peak occurring due to the following exothermic chemical reaction ("hotspot") and / or a pressure drop in the reactor is respectively waited for, and wherein the step (β) for activation can also take place several times,

(g) adding alkylene oxide and carbon dioxide to the mixture resulting from step (β), wherein the alkylene oxide used in step (β) may be the same or different from the alkylene oxide used in step (g) and where appropriate H-functional starter compounds and DMC catalyst are continuously added during the storage in the reactor.

As used herein, the term "continuous" may be defined as the mode of adding a reactant so as to maintain a copolymerization effective concentration of the reactant, i. For example, the metering can be carried out at a constant metering rate, at a varying metering rate or in portions.

In general, alkylene oxides (epoxides) having 2 to 24 carbon atoms can be used to prepare a polyethercarbonate polyol. The alkylene oxides having 2 to 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- l, 2-pentenoxide, 4-methyl-1, 2-pentenoxide, 2-ethyl-1, 2-butene oxide, 1-heptene oxide, 1-octene oxide, 1-nonoxide, 1-decene oxide, 1-undecenoxide, 1-dodecenoxide, 4-methyl-l, 2-pentenoxide, butadiene monoxide, isoprene monoxide, cyclopentene oxide, cyclohexoxide, cycloheptenoxide, cyclooctene oxide, styrene oxide, methylstyrene oxide, pinene oxide, mono- or multiply epoxidized fats as mono-, di- and triglycerides, epoxidized fatty acids, ci C ₂ 4-esters of epoxidized fatty acids, epichlorohydrin, glycidol, and derivatives of glycidol, such as methyl glycidyl ether, ethyl glycidyl ether, 2-ethylhexyl glycidyl ether, All yl glycidyl ethers, glycidyl methacrylate and epoxy-functional alkoxysilanes, such as, for example, 3-glycidyloxypropyltrimethoxysilane, 3- Glycidyloxypropyltriethoxysilane, 3-glycidyloxypropyltripropoxysilane, 3-glycidyloxypropylmethyldimethoxysilane, 3-glycidyloxypropylethyldiethoxysilane, 3-glycidyloxypropyltri-isopropoxysilane. The alkylene oxides used are preferably ethylene oxide and / or propylene oxide and / or 1,2-butylene oxide, particularly preferably propylene oxide.

As a suitable H-functional initiator compound compounds can be used with lation for alkoxy active hydrogen atoms. For the alkoxylation active groups having active H atoms are, for example, -OH, -NI I ₂ (primary amines), -NH- (secondary amines), -SH and -CO2H, preferably -OH and -NH2, are particularly preferred is -OH.

As monofunctional starter compounds alcohols, amines, thiols and carboxylic acids can be used. As monofunctional alcohols can be used: methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, t-butanol, 3-buten-1-ol, 3-butyn-1-ol, 2-methyl 3-buten-2-ol, 2-methyl-3-butyn-2-ol, propargyl alcohol, 2-methyl-2-propanol, lt-butoxy-2-propanol, 1-pentanol, 2-pentanol, 3-pentanol , 1-hexanol, 2-hexanol, 3-hexanol, 1-heptanol, 2-heptanol, 3-heptanol, 1-octanol, 2-octanol, 3-octanol, 4-octanol, phenol, 2-hydroxybiphenyl, 3-hydroxybiphenyl , 4-hydroxybiphenyl, 2-hydroxypyridine, 3-hydroxypyridine, 4-hydroxypyridine. Suitable monofunctional amines are: butylamine, t-butylamine, pentylamine, hexylamine, aniline, aziridine, pyrrolidine, piperidine, morpholine. As monofunctional thiols can be used: ethanethiol, 1-propanethiol, 2-propanethiol, 1-butanethiol, 3-methyl-1-butanethiol, 2-butene-1-thiol, thiophenol. As monofunctional carboxylic acids may be mentioned: formic acid, It acetic acid, propionic acid, butyric acid, fatty acids such as stearic acid, palmitic acid, oleic acid, linoleic acid, linolenic acid, benzoic acid, acrylic acid.

As H-functional starter compounds suitable polyhydric alcohols are beispielwei se dihydric alcohols (such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 1, 4-butanediol, 1, 4-butenediol, 1,4-butynediol, neo pentylglycol, 1,5-pentanediol, methylpentanediols (such as, for example, 3-methyl-1,5-pentanediol), 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, 1,12-dodecanediol, bis- (hydroxymethyl) cyclohexanes (such as, for example, 1,4-bis (hydroxymethyl) cyclohexane), triethylene glycol, tetraethylene glycol, polyethylene glycols, dipropylene glycol, tripropylene glycol, polypropylene glycols, dibutylene glycol and polybutylene glycols); trihydric alcohols (such as trimethylolpropane, glycerol, trishydroxyethyl isocyanurate, castor oil); tetrahydric alcohols (such as pentaerythritol); Polyalcohols (like For example, sorbitol, hexitol, sucrose, starch, starch hydrolysates, cellulose, cellulose hydrolysates, hydroxy-functionalized fats and oils, especially castor oil), and all modifying products of these aforementioned alcohols with different amounts of e-caprolactone. It is also possible to use trihydric alcohols, for example trimethylolpropane, glycerol, trishydroxyethyl isocyanurate and castor oil, in mixtures of--functional starter compounds.

The Fl-functional starter compounds may also be selected from the class of polyether polyols, in particular those having a molecular weight M _n in the range from 100 to 4000 g / mol, preferably from 250 to 2000 g / mol. Preference is given to polyether polyols which are built up from repeating ethylene oxide and propylene oxide units, preferably with a proportion of 35 to 100% propylene oxide units, particularly preferably with a proportion of 50 to 100% propylene oxide units. Fliers may be random copolymers, gradient copolymers, alternating or block copolymers of ethylene oxide and propylene oxide. Suitable polyether polyols composed of repeating propylene oxide and / or ethylene oxide units are, for example, the Desmophen®, Acclaim®, Arcol®, Baycoll®, Bayfill®, Bayflex® Baygal®, PET® and polyether polyols Covestro Deutschland AG (such as Desmophen® 3600Z, Desmophen® 1900U, Acclaim® Polyol 2200, Acclaim® Polyol 40001, Arcol® Polyol 1004, Arcol® Polyol 1010, Arcol® Polyol 1030, Arcol® Polyol 1070, Baycoll® BD 1110, Bayfill® VPPU 0789, Baygal® K55, PET® 1004, Polyether® S180). Further suitable homo-polyethylene oxides are, for example, the Pluriol® E grades from BASF SE, suitable homopolypropylene oxides are, for example, the Pluriol® P grades from BASF SE, suitable mixed copolymers of ethylene oxide and propylene oxide are, for example, Pluronic® PE or Pluriol® RPE brands of BASF SE.

The Fl-functional starter compounds may also be selected from the class of polyesters terpolyole, in particular those having a molecular weight M _n Be in the range of from 200 to 4500 g / mol, preferably 400 to 2500 g / mol. Polyester polyols used are at least difunctional polyesters. Preferably, polyester polyols consist of alternating acid and alcohol units. As acid components z. As succinic acid, maleic acid, maleic anhydride, adipic acid, phthalic anhydride, phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, tetrahydrophthalic anhydride, flexahydrophthalic anhydride or mixtures of said acids and / or anhydrides used. As alcohol components z. Ethanediol, 1,2- Propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 1,4-bis (hydroxymethyl) cyclohexane, diethylene glycol, dipropylene glycol, trimethylolpropane, glycerol, Pentaerythritol or mixtures of the alcohols mentioned ver used. If divalent or polyhydric polyether polyols are used as the alcohol component, polyester polyethers are obtained which can likewise serve as starter compounds for the preparation of the polyether carbonate polyols. If polyether polyols are used to prepare the polyester ether polyols, preference is given to polyether polyols having a number average molecular weight M _{n of} from 150 to 2000 g / mol.

Furthermore, polycarbonate polyols (such as, for example, polycarbonate diols) can be used as H-functional starter compounds, in particular those having a molecular weight M _n in the range from 150 to 4500 g / mol, preferably 500 to 2500, for example by reaction of phosgene, dimethyl carbonate, diethyl carbonate or diphenyl carbonate and di- and / or polyfunctional alcohols or polyester polyols or polyether polyols. Examples of polycarbonate polyols are found, for. As in EP-A 1359177. For example, as the polycarbonate diols Desmophen® C-types of Covestro Germany AG can be used, such as. Desmophen® C 1100 or Desmophen® C 2200.

Polyether polyols used according to the invention are obtained by preparation methods known to the person skilled in the art, for example by anionic polymerization of one or more alkylene oxides having 2 to 24 carbon atoms using at least one H-functional initiator compound containing 2 to 8, preferably 2 to 6, active hydrogen atoms.

As suitable alkylene oxides and H-functional starter compounds, the compounds already described can be used.

Useful polyetherester polyols are those compounds containing ether groups, ester groups and OH groups. Organic dicarboxylic acids having up to 12 carbon atoms are suitable for preparing the polyetheresterpolyols, preferably aliphatic dicarboxylic acids having 4 to 6 carbon atoms or aromatic dicarboxylic acids, which are used singly or in admixture. Examples which may be mentioned are suberic acid, azelaic acid, decanedicarboxylic acid, maleic acid, malonic acid, phthalic acid, pimelic acid and sebacic acid, and in particular glutaric acid, fumaric acid, succinic acid, adipic acid, phthalic acid, terephthalic acid and isoterephthalic acid. In addition to organic dicarboxylic acids also derivatives of these acids, for example their anhydrides and their esters and half esters with low molecular weight, monofunctional alcohols having 1 to 4 carbon atoms can be used. The proportional use of the abovementioned bio-based starting materials, in particular of fatty acids or fatty acid derivatives (oleic acid, soybean oil, etc.) is also possible.

As a further component for the preparation of the polyetherester polyols Polyetherpo lyols are used, which can be obtained as already described.

Polyetheresterpolyole can also be prepared by the alkoxylation, in particular by ethoxylation and / or propoxylation, of reaction products obtained by the reaction of organic dicarboxylic acids and their derivatives and components with Zerewitinoff active hydrogens, in particular diols and polyols. As derivatives of these acids, for example, their anhydrides can be used, such as phthalic anhydride.

Preparation processes of the polyols are described, for example, by Ionescu in "Chemistry and Technology of Polyols for Polyurethanes", Rapra Technology Limited, Shawbury 2005, p.55 et seq. (Chapter 4: Oligo-Polyols for Elastic Polyurethanes), page 263 et seq 8: Polyester Polymers for Elastic Polyurethanes) and in particular on page 311 ff. (Section 13: Polyether Polyols for Rigid Polyurethane Foams) and page 419 ff. (Section 16: Polyester Polyols for Rigid Polyurethane Foams) Service. It is also possible to obtain polyester and polyether polyols via glycolysis of suitable polymer recyclates.

Suitable suspending agents are all polar aprotic, weakly polar aprotic and nonpolar aprotic solvents, which each contain no H-functional groups. As a suspending agent, a mixture of two or more of these suspen sion medium can be used. By way of example, the following polar aprotic solvents may be mentioned at this point: 4-methyl-2-oxo-1,3-dioxolane (also referred to below as cyclic propylene carbonate or cPC), 1,3-dioxolan-2-one (hereinafter also as cyclic ethylene carbonate or cEC), acetone, methyl ethyl ketone, acetonitrile, nitromethane, dimethyl sulfoxide, sulfolane, dimethylformamide, dimethylacetamide and N-methylpyrrolidone. The group of nonpolar and weakly polar aprotic solvents include, for example, ethers, such as dioxane, diethyl ether, methyl tert-butyl ether and tetrahydrofuran, esters, such as ethyl acetate and butyl acetate, hydrocarbons, such as pentane, n-hexane, Benzene and alkylated benzene derivatives (eg toluene, Xylene, ethylbenzene) and chlorinated hydrocarbons, such as chloroform, chlorobenzene, dichlorobenzene and carbon tetrachloride. Preferred suspending agents are 4-methyl-2-oxo-l, 3-dioxolane, l, 3-dioxolan-2-one, toluene, xylene, ethylbenzene, chlorobenzene and dichlorobenzene and mixtures of two or more of these suspending agent is a set, particularly preferred 4-methyl-2-oxo-l, 3-dioxolane and l, 3-dioxolan-2-one or a mixture of 4-methyl-2-oxo-l, 3-dioxolane and l, 3-dioxolan-2-one ,

DMC catalysts are known in principle from the prior art for the homopolymerization of epoxides (see for example US-A 3 404 109, US-A 3 829 505, US-A 3 941 849 and US-A 5 158 922). DMC catalysts which are described, for example, in US Pat. No. 5,470,813, EP-A 700 949, EP-A 743 093, EP-A 761 708, WO-A 97/40086, WO-A 98/16310 and WO-A 00 / 47649 be, have a very high activity in the homopolymerization of epoxides and allow the preparation of polyether polyols and / or Polyethercarbonatpolyo len at very low catalyst concentrations (25 ppm or less). A typical example are the highly active DMC catalysts described in EP-A 700 949 which, in addition to a double metal cyanide compound (eg zinc hexacyanocobaltate (III)) and an organic complex ligand (eg t-butanol), also have a polyether with a number average molecular weight M _n greater contained as 500 g / mol.

In step A), ethanol is added to the polyol containing DMC catalyst as alcohol in an amount of 4% by weight to 12% by weight, based on 100% by weight of polyol. Preference is given to using 5% by weight to 9% by weight of ethanol, based on 100% by weight of polyol, in step A).

Optionally, a filter aid is presented in step A). Filter aids are used, for example, to prevent clogging of the filter. Examples of filter aids are cellulose, silica gel, alumina, activated carbon, diatomaceous earth or perlite.

The mixture is then heated in step A), preferably to a temperature of 80 to 180 ° C, particularly preferably 80 to 120 ° C. The mixture in step A) is preferably heated for 100 to 140 minutes.

In the preparation of polyols in the presence of a DMC catalyst, the polyols are transferred after the reaction in a secondary reactor so that free alkylene oxide can still react. Subsequently, unreacted Mo nomere or other volatile constituents are separated from the polyols by distillation as a rule. therefore In a preferred embodiment of this invention, step A) is carried out in such a post-reactor in which alcohol and optionally filter aid to the polyol ent holding DMC catalyst is added to the post-reactor prior to the distillation of the polyol.

Step B)

The resulting mixture from step A) is then filtered. Filtra tion methods are described for example by T. Sparks in "Solid-Fiquid Filtration", Butterworth Heinemann, Oxford 2011. Preferably, the mixture is filtered through a depth filter medium. The mixture resulting from step A) can be filtered at a temperature of from 10 to 150.degree. C., preferably from 80 to 120.degree. It is also possible to carry out the filtration under pressure, preferably a pressure of 4 to 8 bar is set.

Step CI

The alcohol can then be separated from the purified polyol by separation methods known to the person skilled in the art to the filtration in step B). To separate the alcohol, it is possible, for example, to use thermal separation processes, such as distillation or stripping, or mechanical separation processes, such as membrane filtration or dialysis. Preference is given to using thermal separation processes or combinations of thermal and non-thermal separation processes to separate off the alcohol. Particularly preferred are evaporation equipment, such as falling film evaporator or Vakuumver steamer, or Strippingkolonnen, as well as combinations of the mentioned used. Most preferably, a falling film evaporator or thin film evaporator is used to separate the alcohol from the purified polyol.

In a first embodiment, the invention relates to a process for the separation of a double metal cyanide (DMC) catalyst, comprising the steps

A) introducing a polyol containing DMC catalyst, an alcohol and, if appropriate, a filter aid into a reactor, the mixture being heated,

B) filtration of the mixture from step A),

C) optionally separating the alcohol from the filtrate of step B), characterized in that used in step A) as alcohol 4 wt .-% to 12 wt .-% ethanol, based on 100 wt .-% of polyol, without a chelating agent.

In a second embodiment, the invention relates to a process according to embodiment 1, characterized in that the polyol is a polyether polyol and / or a polyether carbonate polyol.

In a third embodiment, the invention relates to a method according to embodiment form 1 or 2, characterized in that used in step A) as alcohol 5 wt .-% to 9 wt .-% ethanol. In a fourth embodiment, the invention relates to a method according to any one of embodiments 1 to 3, characterized in that in step A), the mixture is heated to a temperature of 80 ° C to l80 ° C.

In a fifth embodiment, the invention relates to a method according to one of the embodiments 1 to 4, characterized in that in step A) the mixture is heated for a time of 100 minutes to 140 minutes.

In a sixth embodiment, the invention relates to a method according to any one of embodiments 1 to 5, characterized in that in step B), the filtration is carried out at a temperature of 80 ° C to l20 ° C.

In a seventh embodiment, the invention relates to a method according to one of the embodiments 1 to 6, characterized in that in step B), the filtration is carried out at a pressure of 4 bar to 8 bar.

In an eighth embodiment, the invention relates to a method according to one of the embodiments 1 to 7, comprising the step

C) separating the alcohol from the filtrate of step B). In a ninth embodiment, the invention relates to a method according to Ausfüh tion form 8, characterized in that the alcohol in step C) fering device by a Verdamp, a stripping column or a combination of the above is separated abge. In a tenth embodiment, the invention relates to a method according to Ausfüh tion form 9, characterized in that the evaporation device is a Fallfilmver evaporator or a thin-film evaporator.

In an eleventh embodiment, the invention relates to a process according to one of the embodiments 1 to 10, characterized in that the polyol is a polyether carbonate polyol.

In a twelfth embodiment, the invention relates to a process according to embodiment 11, characterized in that the polyethercarbonate polyol is prepared by addition of carbon dioxide and alkylene oxide to an H-functional starter compound in the presence of a DMC catalyst, characterized by the steps:

(A) submitting a subset of the H-functional initiator compound and / or suspending agent, which does not contain H-functional groups, in a reactor each together with DMC catalyst and optionally removing water and / or other volatile compounds by elevated temperature and / or reduced pressure ("drying"),

(β) Activation of the DMC catalyst by addition of a partial amount (based on the total amount of alkylene oxide used in the activation and copolymerization) of alkylene oxide to that resulting from step (a) the mixture, said addition of a subset of alkylene oxide given - If it can be done in the presence of C0 ₂ , and in which case the temperature peak occurring due to the following exothermic chemical reaction ("hotspot") and / or a pressure drop in the reactor, respectively, and wherein the step (ß) to activate several times can

(g) addition of alkylene oxide and carbon dioxide to the mixture resulting from step (β), wherein the alkylene oxide used in step (β) may be identical or different from the alkylene oxide used in step (g) and optionally H-functional starter compounds and DMC catalyst are added continuously during the addition in the reactor. Experimental part

feedstocks

Polyol A Polyethercarbonate polyol prepared via DMC-catalyzed polymerization of propylene oxide in the presence of CO2 having a functionality of 3, an OH number of 56.1 mg KOH / g, 12% by weight.

% built-in CO2 and a concentration of 200 ppm DMC catalyst.

Ethanol with 2% by weight of methyl ethyl ketone denatured ethanol (from Fluka)

General Experimental Procedure 200 g of polyol A were introduced into a 300 ml pressure reactor and ethanol (see Table 1) was added. The mixture was heated to the appropriate temperature (see Table 1) and stirred for 120 minutes (Step A)). Subsequently, the mixture from step A) was removed from the reactor and transferred to a pressure filter for filtration. The mixture was stirred at l00 ° C and 6 bar pressure over a Becopad ^® 450 filter layer (thickness: 3.9 mm, diameter: 50 mm, area: 157 mm ² Material: cellulose, separation zone:

1.0 to 2.0 pm) from Eaton (step B)). The ethanol present in the filtrate was separated in a subsequent step on a thin-film evaporator and determines the proportion of Co / Zn residues (step C)). Detailed information on the proportions of ethanol used and the temperature used in step A) of the individual examples are given in Table 1.

The proportion of DMC catalyst in the purified polyol A is determined by the contained Co / Zn residues in the purified polyol A. The proportion of Co / Zn residue is determined by elemental analysis with optical emission spectrometry using inductively coupled plasma (ICP-OES). The ICP-OES was performed with a SPECTRO ARCOS from SPECTRO and an argon plasma. To determine the Co / Zn residues, the proportions for Co were determined via the emission at the wavelengths 228.616 nm, 230.786 nm and 238.892 nm, and for Zn at 202.613 nm, 206.266 nm and 213.856 nm, respectively. Table 1

* Comparative Example

based on the total weight of the polyol

Comparative Example 1 in Table 1 indicates the proportion of Co / Zn residues in polyol A by the process according to the invention, wherein no ethanol was added in step A). The inventive method leads in Examples 5 and 7 to a significant reduction in the Co / Zn residues in the polyol component. In contrast, in Comparative Examples 2 to 4 and 6, non-inventive amounts of ethanol in step A) were added to the polyol component. The proportion of Co / Zn residues in Comparative Examples 2 to 4 compared to Example 5, in comparison example 6 compared to Example 7 significantly increased.

Claims

claims:

A process for separating a double metal cyanide (DMC) catalyst from polyol comprising the steps

A) providing a polyol containing DMC catalyst, an alcohol and optionally a filter aid in a reactor, wherein the mixture is heated,

B) filtration of the mixture from step A),

C) optionally separating the alcohol from the filtrate of step B), characterized in that used in step A) as the alcohol 4 wt .-% to 12 wt .-% ethanol, based on 100 wt .-% polyol, without a chelating agent become.

2. The method according to claim 1, characterized in that the polyol is a Polyetherpo lyol and / or a polyether carbonate polyol.

3. The method according to claim 1 or 2, characterized in that in step A) as Al kohol 5 wt .-% to 9 wt .-% ethanol are used.

4. The method according to any one of claims 1 to 3, characterized in that in step

A) the mixture is heated to a temperature of 80 ° C to 180 ° C.

5. The method according to any one of claims 1 to 4, characterized in that in step

A) the mixture is heated for a time of 100 minutes to 140 minutes.

6. The method according to any one of claims 1 to 5, characterized in that in step B) the filtration is carried out at a temperature of 80 ° C to 120 ° C.

7. The method according to any one of claims 1 to 6, characterized in that in step

B) the filtration is carried out at a pressure of 4 bar to 8 bar.

8. The method according to any one of claims 1 to 7, comprising the step

C) separating the alcohol from the filtrate of step B).

A process according to claim 8, characterized in that the alcohol in step C) is separated by an evaporation means, a stripping column or a combination thereof.

10. The method according to claim 9, characterized in that the evaporation device is a falling-film evaporator or a thin-film evaporator.

11. The method according to any one of claims 1 to 10, characterized in that the Po lyol is a polyether carbonate polyol.

12. The method according to claim 11, characterized in that the Polyethercarbonatpo lyol is prepared by addition of carbon dioxide and alkylene oxide to a Fl-functional starter compound in the presence of a DMC catalyst, characterized by the steps:

(A) submission of a subset of the Fl-functional initiator compound and / or suspending agent containing no Fl-functional groups in a reactor each together with DMC catalyst and optionally removing water and / or other volatile compounds by increased Tempe temperature and / or reduced pressure ("drying"),

(β) Activation of the DMC catalyst by adding a portion (based on the total amount of alkylene oxide used in the activation and copolymerization) of alkylene oxide to the mixture resulting from step (a), this addition of a portion of alkylene oxide where appropriate, in the presence of C0 ₂ can be carried out, and in which case the temperature peak occurring due to the following exothermic chemical reaction ("Flotspot") and / or a pressure drop in the reactor is respectively waited, and wherein the step (ß) to activate several times (g) addition of alkylene oxide and carbon dioxide to the mixture resulting from step (β), wherein the alkylene oxide used in step (β) may be the same or different from the alkylene oxide used in step (g) and optionally fluoro-functional Starter compounds and DMC catalyst are added continuously during the addition in the reactor.