CN114729114A

CN114729114A - Method for producing polyether carbonate polyols

Info

Publication number: CN114729114A
Application number: CN202080083507.1A
Authority: CN
Inventors: S·布劳恩; J·霍夫曼; M·特拉文; M·沃哈克
Original assignee: Covestro Intellectual Property GmbH and Co KG
Current assignee: Covestro Intellectual Property GmbH and Co KG
Priority date: 2019-12-04
Filing date: 2020-12-01
Publication date: 2022-07-08
Also published as: EP4069762A1; KR20220111266A; WO2021110691A1

Abstract

The invention relates to a method for producing polyether carbonate polyols, comprising the step of reacting alkylene oxides with carbon dioxide in the presence of an H-functional starter compound and a double metal cyanide catalyst, characterized in that: (α) a portion of the amount of H-functional starter substance and/or of the suspension agent free of H-functional groups is preloaded in a reactor, in each case together with the DMC catalyst, (β) a portion of the amount of alkylene oxide is added to the mixture from step (α) at a temperature of from 90 to 150 ℃, wherein the addition of the alkylene oxide is then interrupted, (γ) alkylene oxide, carbon dioxide and a mixture comprising an unactivated double metal cyanide catalyst and an H-functional starter compound are metered continuously into the mixture obtained from (β), wherein the H-functional starter compound is a polyol having a number-average molar mass of from 550 to 2000 g/mol according to DIN 55672-1.

Description

Method for producing polyether carbonate polyols

The invention relates to a method for producing polyether carbonate polyols from H-functional starter compounds, alkylene oxides and carbon dioxide in the presence of Double Metal Cyanide (DMC) catalysts. It further relates to polyether carbonate polyols obtained by the process according to the invention.

The preparation of polyether carbonate polyols by catalytic reaction of alkylene oxides (epoxides) and Carbon Dioxide in the presence of H-functional starter substances ("starters") has been the subject of considerable research for more than 40 years (e.g.Inoue et al, Copolymerization of Carbon Dioxide and Epoxide with Organometallic Compounds; Die Makromolekulare Chemie 130, 210-220, 1969). This reaction is schematically shown in scheme (I), wherein R is an organic group, such as alkyl, alkylaryl or aryl, each of which may also contain heteroatoms, such as O, S, Si and the like, and wherein e, f and g are integers, and wherein the products shown here in scheme (I) with respect to the polyethercarbonate polyols are to be understood as meaning only that blocks having the structure shown can in principle be present in the resulting polyethercarbonate polyol, but the order, number and length of the blocks and the OH functionality of the starter can vary and are not limited to the polyethercarbonate polyols shown in scheme (I). This reaction (see scheme (I)) is very advantageous from an ecological point of view, since it represents the conversion of greenhouse gases such as CO₂And converted into a polymer. The further product formed, which is in fact a by-product, is a cyclic carbonate as shown in scheme (I) (e.g. at R = CH)₃Propylene carbonate).

EP 0222453 discloses a process for the preparation of polycarbonates from alkylene oxides and carbon dioxide using a catalyst system consisting of a DMC catalyst and a co-catalyst, such as zinc sulfate. This polymerization is initiated here by bringing a portion of the alkylene oxide into contact with the catalyst system at once. Only thereafter is the remaining amounts of alkylene oxide and carbon dioxide metered in simultaneously. The amount of 60 wt.% of alkylene oxide relative to the H-functional starter compound as shown in EP 0222453 a2 for the activation step in examples 1 to 7 is high and has the disadvantage of constituting a safety risk for industrial large-scale applications due to the high exothermicity of the homopolymerization of the alkylene oxide.

WO 2016/079065 a1 discloses a continuous process for preparing polyether carbonate polyols, in which a mixture of H-functional starter substance and activated DMC catalyst, alkylene oxide and carbon dioxide is metered in. However, no indication is given of the concentration of free alkylene oxide.

In order to prepare polyether carbonate polyols on an industrial scale, a method for carrying out the reaction is required which ensures product quality and safety.

It was therefore an object to provide a process for preparing polyether carbonate polyols, which is characterized by a low concentration of free alkylene oxide in the process, a narrow molar mass distribution of the polyether carbonate polyols obtained and a good selectivity. In addition, the process should result in shorter residence times, which can reduce reactor volume and reduce capital costs.

Surprisingly, it has been found that the object of the present invention is achieved by a process for preparing polyether carbonate polyols, comprising the step of reacting an alkylene oxide with carbon dioxide in the presence of an H-functional starter compound and a double metal cyanide catalyst, characterized in that:

(. alpha.) A portion of the amount of H-functional starter substance and/or of the suspending agent which does not contain H-functional groups is preloaded in the reactor, in each case together with the DMC catalyst,

(β) adding a portion of the amount of alkylene oxide to the mixture from step (α) at a temperature of from 90 to 150 ℃, wherein the addition of the alkylene oxide is then interrupted,

(γ) continuously metering the alkylene oxide, carbon dioxide and a mixture comprising an unactivated double metal cyanide catalyst and an H-functional starter compound into the mixture obtained from (β), wherein the H-functional starter compound is a polyol having a number-average molar mass according to DIN 55672-1 of from 550 to 2000 g/mol.

In a preferred embodiment, the present invention relates to a process for preparing polyether carbonate polyols, comprising the step of reacting alkylene oxides with carbon dioxide in the presence of an H-functional starter compound and a double metal cyanide catalyst, characterized in that:

(. alpha.) A portion of the amount of H-functional starter substance and/or of the suspending agent which is free of H-functional groups is pre-loaded in the reactor, optionally together with DMC catalyst in each case,

(gamma) continuously metering alkylene oxide, carbon dioxide and a mixture comprising an unactivated double metal cyanide catalyst and an H-functional starter compound into the mixture obtained from (beta), wherein the H-functional starter compound is a polyol having a number-average molar mass according to DIN 55672-1 of from 550 to 2000 g/mol,

(δ) the reaction mixture obtained in step (γ) is retained in the reactor or continuously transferred to a post-reactor, wherein the content of free alkylene oxide in the reaction mixture is in each case reduced by post-reaction under the selected process conditions (including temperature and residence time).

The polyether carbonate polyols prepared in accordance with the invention in the presence of Double Metal Cyanide (DMC) catalysts are distinguished by the fact that they also contain ether groups between the carbonate groups. This means that the e/f ratio is preferably from 2:1 to 1:20, more preferably from 1.5:1 to 1:10, relative to formula (Ia).

Step (a):

the process of the present invention for preparing polyether carbonate polyols by addition of alkylene oxides and carbon dioxide onto H-functional starter substances comprises a step (. alpha.).

The H-functional starter substance and/or the suspending agent free of H-functional groups can first be preloaded into the reactor, preferably with a partial amount of H-functional starter substance. Subsequently, a quantity of DMC catalyst, which is preferably not activated, may be added to the reactor. The order of addition is not important here. It is also possible to first fill the DMC catalyst and subsequently fill the suspension agent into the reactor. Alternatively, it is also possible to first suspend the DMC catalyst in an inert suspending agent and then introduce this suspension into the reactor. By means of the suspending agent, a sufficient heat exchange area with the reactor wall or cooling elements installed in the reactor is provided, so that the reaction heat released can be removed very well. Furthermore, the suspending agent provides heat capacity in the event of failure of cooling, so that the temperature in this case can be kept below the decomposition temperature of the reaction mixture.

The suspending agent does not contain H functional groups. Suitable suspending agents are all polar aprotic, weakly polar aprotic and nonpolar aprotic solvents which contain no H functional groups. The suspending agents used may also be mixtures of two or more of these suspending agents. The following polar aprotic solvents are mentioned here by way of example: 4-methyl-2-oxo-1, 3-dioxolane (hereinafter also referred to as cyclic propylene carbonate or cPC), 1, 3-dioxolan-2-one (hereinafter also referred to as cyclic ethylene carbonate or cEC), acetone, methyl ethyl ketone, acetonitrile, nitromethane, dimethyl sulfoxide, sulfolane, dimethylformamide, dimethylacetamide, N-methylpyrrolidone. One class of aprotic and weakly polar aprotic solvents includes, 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 (e.g., toluene, xylene, ethylbenzene) and chlorinated hydrocarbons such as chloroform, chlorobenzene, dichlorobenzene and carbon tetrachloride. The suspending agents used are preferably 4-methyl-2-oxo-1, 3-dioxolane, 1, 3-dioxolan-2-one, toluene, xylene, ethylbenzene, chlorobenzene and dichlorobenzene and mixtures of two or more of these suspending agents; particular preference is given to 4-methyl-2-oxo-1, 3-dioxolane and 1, 3-dioxolan-2-one or mixtures of 4-methyl-2-oxo-1, 3-dioxolane and 1, 3-dioxolan-2-one.

Also suitable as suspending agents are aliphatic lactones, aromatic lactones, lactides, cyclic carbonates having at least three optionally substituted methylene groups between the oxygen atoms of the carbonate groups, aliphatic cyclic anhydrides and aromatic cyclic anhydrides.

The aliphatic or aromatic lactone in the present invention is a cyclic compound having an ester bond in a ring, and is preferably a cyclic compound having an ester bond in a ring

4-membered ring lactones, for example beta-propiolactone, beta-butyrolactone, beta-valerolactone, beta-caprolactone, beta-isohexanolactone, beta-methyl-beta-valerolactone,

5-membered ring lactones, for example gamma-butyrolactone, gamma-valerolactone, 5-methylfuran-2 (3H) -one, 5-methylenedihydrofuran-2 (3H) -one, 5-hydroxyfuran-2 (5H) -one, 2-benzofuran-1 (3H) -one and 6-methyl-2-benzofuran-1 (3H) -one,

6-membered ring lactones, for example delta-valerolactone, 1, 4-dioxan-2-one, dihydrocoumarin, 1H-isochromen-1-one, 8H-pyrano [3,4-b ] pyridin-8-one, 1, 4-dihydro-3H-isochromen-3-one, 7, 8-dihydro-5H-pyrano [4,3-b ] pyridin-5-one, 4-methyl-3, 4-dihydro-1H-pyrano [3,4-b ] pyridin-1-one, 6-hydroxy-3, 4-dihydro-1H-isochromen-1-one, 7-hydroxy-3, 4-dihydro-2H-chromen-2-one, 3-ethyl-1H-isochromen-1-one, 3- (hydroxymethyl) -1H-isochromen-1-one, 9-hydroxy-1H, 3H-benzo [ de ] isochromen-1-one, 6, 7-dimethoxy-1, 4-dihydro-3H-isochromen-3-one and 3-phenyl-3, 4-dihydro-1H-isochromen-1-one,

7-membered ring lactones, for example ε -caprolactone, 1, 5-dioxepan-2-one, 5-methyloxepan-2-one, oxepan-2, 7-dione, thiepan-2-one, 5-chlorooxoheterocycloheptan-2-one, (4)S) -4- (propan-2-yl) oxepan-2-one, 7-butyloxepan-2-one, 5- (4-aminobutyl) oxepan-2-one, 5-phenyloxepan-2-one, 7-hexyloxepan-2-one, (5)S,7S) -5-methyl-7- (propan-2-yl) oxepan-2-one, 4-methyl-7- (propan-2-yl) oxepan-2-one,

more polybasic cyclic lactones, such as (7E) -oxetan-7-en-2-one.

Particularly preferred are epsilon-caprolactone and dihydrocoumarin.

The lactide in the present invention is a cyclic compound having two or more ester bonds in the ring, preferably glycolide (1, 4-dioxane-2, 5-dione), L-lactide (L-3, 6-dimethyl-1, 4-dioxane-2, 5-dione), D-lactide, DL-lactide, meso-lactide and 3-methyl-1, 4-dioxane-2, 5-dione, 3-hexyl-6-methyl-1, 4-dioxane-2, 5-dione, 3, 6-di (but-3-en-1-yl) -1, 4-dioxane-2, 5-dione (in each case including the optically active form). L-lactide is particularly preferred.

Cyclic carbonates having at least three optionally substituted methylene groups between the oxygen atoms of the carbonate groups are preferably trimethylene carbonate, neopentyl glycol carbonate (5, 5-dimethyl-1, 3-dioxan-2-one), 2, 4-trimethylpentane-1, 3-diol carbonate, 2-dimethylbutane-1, 3-diol carbonate, butane-1, 3-diol carbonate, 2-methylpropane-1, 3-diol carbonate, pentane-2, 4-diol carbonate, 2-methylbutane-1, 3-diol carbonate, TMP monoallyl ether carbonate, pentaerythritol diallyl ether carbonate, 5- (2-hydroxyethyl) -1, 3-dioxan-2-one, 5- [2- (benzyloxy) ethyl ] -1, 3-dioxan-2-one, 4-ethyl-1, 3-dioxolan-2-one, 5-ethyl-5-methyl-1, 3-dioxan-2-one, 5, 5-diethyl-1, 3-dioxan-2-one, 5-methyl-5-propyl-1, 3-dioxan-2-one, 5- (phenylamino) -1, 3-dioxan-2-one and 5, 5-dipropyl-1, 3-dioxan-2-one. Particular preference is given to trimethylene carbonate and neopentyl glycol carbonate.

The cyclic acid anhydride is preferably maleic anhydride, phthalic anhydride, cyclohexane-1, 2-dicarboxylic anhydride, biphenylic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, nadic anhydride and chlorinated products thereof, succinic anhydride, glutaric anhydride, diglycolic anhydride, 1, 8-naphthalic anhydride, succinic anhydride, dodecenyl succinic anhydride, tetradecenyl succinic anhydride, hexadecenyl succinic anhydride, octadecenyl succinic anhydride, 3-and 4-nitrophthalic anhydride, tetrachlorophthalic anhydride, tetrabromophthalic anhydride, itaconic anhydride, dimethylmaleic anhydride, allyl nadic anhydride, 3-methylfuran-2, 5-dione, 3-methyldihydrofuran-2, 5-dione, dihydro-2H-pyran-2, 6(3H) -dione, 1, 4-dioxane-2, 6-dione, 2H-pyran-2, 4,6(3H,5H) -trione, 3-ethyldihydrofuran-2, 5-dione, 3-methoxydihydrofuran-2, 5-dione, 3- (prop-2-en-1-yl) dihydrofuran-2, 5-dione, N- (2, 5-dioxotetrahydrofuran-3-yl) carboxamide, and 3[ (2E) -but-2-en-1-yl ] dihydrofuran-2, 5-dione. Succinic anhydride, maleic anhydride and phthalic anhydride are particularly preferred.

The suspending agents used may also be mixtures of two or more of the suspending agents mentioned. Most preferably, the suspending agent used in step (α) is most preferably 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, carbon tetrachloride, epsilon-caprolactone, dihydrocoumarin, trimethylene carbonate, neopentyl glycol carbonate, 3, 6-dimethyl-1, 4-dioxane-2, 5-dione, di-ketone, N-methyl pyrrolidone, N-methyl ether, N-carbonate, N-methyl ether, N-2, N, at least one compound of succinic anhydride, maleic anhydride and phthalic anhydride.

In one embodiment of the present invention, the suspending agent which does not contain H functions is preloaded in step (. alpha.) in the reactor, optionally together with the DMC catalyst, without H-functional starter substance being preloaded in the reactor here. Alternatively, it is also possible to preload in step (. alpha.) in the reactor a suspending agent which does not contain H functional groups and additionally a partial amount of H functional starter substance(s) and optionally DMC catalyst.

The DMC catalyst is preferably used in such an amount that the DMC catalyst content in the reaction product obtained from step (γ) is from 10 to 10000 ppm, more preferably from 20 to 5000 ppm, most preferably from 50 to 500 ppm.

In a preferred embodiment, in step (α), an inert gas (e.g. argon or nitrogen), an inert gas/carbon dioxide mixture or carbon dioxide is introduced into the resulting mixture of (i) a portion of the amount of H-functional starter substance and/or suspending agent and (ii) DMC catalyst at a temperature of from 90 ℃ to 150 ℃, more preferably from 100 ℃ to 140 ℃, and a reduced pressure (absolute) of from 10 mbar to 800 mbar, more preferably from 50 mbar to 200 mbar, is simultaneously applied.

In an alternative preferred embodiment, in step (α), the resulting mixture of (i) a portion of the amount of H-functional starter substance(s) and/or suspending agent and (ii) DMC catalyst is subjected at least once, preferably three times, to 1.5 to 10 bar (absolute), more preferably 3 to 6 bar (absolute), of an inert gas (e.g. argon or nitrogen), an inert gas/carbon dioxide mixture or carbon dioxide at a temperature of from 90 to 150 ℃, more preferably from 100 to 140 ℃, and the overpressure is then reduced in each case to about 1 bar (absolute).

The DMC catalyst can be added, for example, in solid form or as a suspension in a suspending agent or a mixture of at least two suspending agents.

In another preferred embodiment, in step (. alpha.),

(α -I) pre-loading with a partial amount of H-functional starter substance and/or suspending agent, and

(alpha-II) bringing the temperature of the partial amount of H-functional starter substance and/or the suspending agent to 50 to 200 ℃, preferably 80 to 160 ℃, more preferably 100 to 140 ℃, and/or reducing the pressure in the reactor to less than 500 mbar, preferably 5 to 100 mbar, wherein optionally an inert gas stream (e.g. argon or nitrogen), an inert gas/carbon dioxide stream or a carbon dioxide stream is passed through the reactor,

wherein a double metal cyanide catalyst is added to the partial amount of H-functional starter substance and/or the suspending agent in step (. alpha. -I) or immediately thereafter in step (. alpha. -II), and

wherein the suspending agent does not contain H functional groups.

Step (β):

step (a)Beta) is used to activate the DMC catalyst. Step (. beta.) is preferably carried out under a carbon dioxide atmosphere. Activation in the context of the present invention means the step of adding a portion of the amount of alkylene oxide to the DMC catalyst suspension at a temperature of from 90 ℃ to 150 ℃ and then interrupting the addition of alkylene oxide, wherein heat generation which can lead to temperature peaks ("hot spots") is observed as a result of the subsequent exothermic chemical reaction, and also as a result of the alkylene oxide and optionally CO₂Pressure drop in the reactor was observed. The process step of activation is carried out by reacting a portion of the amount of alkylene oxide, optionally in CO₂In the presence of a DMC catalyst until a period of heat generation has occurred. Optionally in separate steps, optionally in CO₂The partial amount of alkylene oxide is added to the DMC catalyst in the presence of this and the addition of alkylene oxide can then be interrupted in each case. In this case, the process step of activation comprises the step of optionally adding CO to a first partial amount of alkylene oxide₂The DMC catalyst is added in the presence until a period of heat generation has occurred after the last partial amount of alkylene oxide has been added. Generally, a step of drying the DMC catalyst and optionally the H-functional starter substance at elevated temperature and/or under reduced pressure can be provided before the activation step, wherein optionally an inert gas is passed through the reaction mixture.

The metering in of the alkylene oxide (and optionally carbon dioxide) can in principle be effected in different ways. The metering can be started under vacuum or under a preselected pre-pressure (Vordruck). The pre-pressure is preferably set by introducing carbon dioxide, wherein the pressure (absolute) is from 5 mbar to 100 bar, preferably from 10 mbar to 50 bar, preferably from 20 mbar to 50 bar.

In a preferred embodiment, the amount of alkylene oxide used in the activation in step (β) is from 0.1 to 25.0 wt. -%, preferably from 1.0 to 20.0 wt. -%, more preferably from 2.0 to 16.0 wt. -%, based on the dosimeter used in step (α). The alkylene oxide can be added in one step or in portions in the form of a plurality of partial amounts. Preferably, after addition of a portion of the amount of alkylene oxide, the addition of alkylene oxide is interrupted until heat generation occurs and the next portion of the amount of alkylene oxide is not added until then.

Step (y):

according to the invention, alkylene oxide, carbon dioxide and a mixture comprising unactivated DMC catalyst and an H-functional starter compound, wherein the H-functional starter compound is a polyol having a number-average molar mass of 550 to 2000 g/mol, are metered continuously into the reactor in step (. gamma.).

The metered addition of carbon dioxide, alkylene oxide, a mixture comprising non-activated DMC catalyst and H-functional starter compound, wherein the H-functional starter compound is a polyol having a number-average molar mass of from 550 to 2000 g/mol, and optionally further H-functional starter compound, can be carried out simultaneously or successively (in portions); for example, the entire amount of carbon dioxide, the entire amount of the mixture comprising the non-activated DMC catalyst and the H-functional starter compound, wherein the H-functional starter compound is a polyol having a number-average molar mass of 550 to 2000 g/mol, the amount of further H-functional starter substance and/or the amount of alkylene oxide metered into step (. gamma.) can be added all at once or continuously. The term "continuous" as used herein may be defined as a mode of reactant addition such that the concentration of reactants effective for copolymerization is maintained, i.e., the metering may be performed, for example, at a constant metering rate, at a variable metering rate, or in portions.

The CO can be gradually or stepwise increased or decreased during the addition of alkylene oxide, a mixture comprising non-activated DMC catalyst and H-functional starter compound (wherein the H-functional starter compound is a polyol having a number average molar mass of 550 to 2000 g/mol), and/or a further H-functional starter substance₂The pressure, or to keep it constant. Preferably, the total pressure is kept constant during the reaction by metering in additional carbon dioxide. Simultaneously or sequentially with the metering of carbon dioxide, a mixture comprising the unactivated DMC catalyst and an H-functional starter compound (wherein the H-functional starter compound is a polyol having a number average molar mass of 550 to 2000 g/mol), and/or further H-functional starter substances. The alkylene oxide can be metered in at a constant metering rate, or gradually or stepwise increasing or decreasing the metering rate, or portionwise. Preferably, the alkylene oxide is added to the reaction mixture at a constant addition rateIn the above-mentioned material. If a plurality of alkylene oxides is used for the synthesis of the polyether carbonate polyols, the alkylene oxides can be metered in individually or as mixtures. The metering in of the alkylene oxide, of the mixture comprising the unactivated DMC catalyst and the H-functional starter compound (wherein the H-functional starter compound is a polyol having a number-average molar mass of 550 to 2000 g/mol) and/or of the further H-functional starter compound can take place simultaneously or successively (in portions) via individual metering in (addition) each or via one or more metering in, wherein the alkylene oxide and/or the further H-functional starter substance can be metered in individually or in the form of a mixture. Random, alternating, block-wise or gradient polyether carbonate polyols can be synthesized via the manner and/or sequence of metering in the further H-functional starter substance, the alkylene oxide, the mixture comprising the unactivated DMC catalyst and the H-functional starter compound (wherein the H-functional starter compound is a polyol having a number-average molar mass of 550 to 2000 g/mol) and/or carbon dioxide.

In a preferred embodiment, the process is carried out as a semibatch process and, in step (γ), the metering in of the H-functional starter substance is ended at a point in time before the addition of the alkylene oxide.

Preferably, an excess of carbon dioxide is used based on the calculated amount of carbon dioxide incorporated in the polyether carbonate polyol, since an excess of carbon dioxide is advantageous due to the reaction inertness of carbon dioxide. The amount of carbon dioxide can be determined by the total pressure (absolute) under the respective reaction conditions (in the present invention, the total pressure (absolute) is defined as the sum of the partial pressures of the alkylene oxide and carbon dioxide used). It has been found that the total pressure (absolute) which is advantageous for the copolymerization for preparing the polyether carbonate polyols is from 5 to 120 bar, preferably from 10 to 110 bar, more preferably from 20 to 100 bar. The carbon dioxide can be fed continuously or discontinuously. Depending on how fast the alkylene oxide is consumed and whether the product should contain optionally no CO₂The polyether block of (1). The amount of carbon dioxide (given as pressure) can likewise be varied during the alkylene oxide addition. CO 2₂The metering into the reactor can be carried out in gaseous or liquid state. CO 2₂It can also be added to the reactor in solid form,and then converted to a gaseous, dissolved, liquid and/or supercritical state under the selected reaction conditions. Carbon dioxide can be metered into the gas or liquid phase.

A preferred embodiment of the process according to the invention is characterized in particular in that the entire amount of H-functional starter substance is added in step (. gamma.). This addition can be carried out by constant metering rate, by variable metering rate or in portions.

It has also been found for the process of the invention that the copolymerization (step (. gamma.)) for preparing the polyether carbonate polyols is advantageously carried out at from 50 ℃ to 150 ℃, preferably from 60 ℃ to 145 ℃, more preferably from 70 ℃ to 140 ℃, very particularly preferably from 90 ℃ to 130 ℃. If a temperature below 50 ℃ is set, the reaction generally becomes very slow. At temperatures above 150 ℃, the amount of undesirable by-products increases dramatically.

Steps (α), (β) and (γ) may be carried out in the same reactor, or may each be carried out separately in a different reactor. A particularly preferred type of reactor is a stirred tank.

The polyether carbonate polyols can be prepared in stirred tanks, which are cooled, depending on the embodiment and the mode of operation, by reactor jackets, cooling surfaces located internally and/or in pump-around systems. Particular attention should be paid to the metering rate of the alkylene oxide both in semibatchwise applications, in which the product is removed only after the end of the reaction, and in continuous applications, in which the product is removed continuously. The metering rate should be adjusted so that the alkylene oxide reacts sufficiently rapidly despite the carbon dioxide inhibiting effect. The concentration of free alkylene oxide in the reaction mixture during the activation step (step β) is preferably > 0 wt. -% to 100 wt. -%, more preferably > 0 wt. -% to 50 wt. -%, most preferably > 0 wt. -% to 20 wt. -%, in each case based on the weight of the reaction mixture. The concentration of free alkylene oxide in the reaction mixture during the reaction (step γ) is preferably > 0 to 40 wt. -%, more preferably > 0 to 25 wt. -%, most preferably > 0 to 15 wt. -%, in each case based on the weight of the reaction mixture.

The polyether carbonate polyols are preferably prepared in a continuous process.

The subject of the present invention is therefore also a process in which, in step (γ), a mixture comprising an unactivated DMC catalyst and an H-functional starter compound, wherein the H-functional starter compound is a polyol having a number-average molar mass of from 550 to 2000 g/mol, and alkylene oxide are metered continuously ("copolymerized") into the reactor in the presence of carbon dioxide, and in which the resulting reaction mixture (comprising the reaction product) is removed continuously from the reactor.

The amount of DMC catalyst used is preferably selected so that the content of DMC catalyst in the reaction product obtained from step (γ) is from 10 to 10000 ppm, more preferably from 20 to 5000 ppm, most preferably from 50 to 500 ppm.

Preferably, steps (α) 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 (γ). It is also possible to carry out steps (. alpha.,. beta.) and (. gamma.) in one reactor.

The term "continuous" as used herein can be defined as a mode of addition of the associated catalyst or reactant that maintains a substantially continuous effective concentration of the DMC catalyst or reactant. The catalyst may be fed in a truly continuous manner or in relatively close increments. Continuous addition of starter can likewise be effected in a truly continuous manner or incrementally. Without departing from the present process, the DMC catalyst or reactant is added incrementally such that the concentration of the added material is reduced to substantially 0 for a period of time before the next incremental addition. However, it is preferred to maintain the DMC catalyst concentration at substantially the same concentration for the major portion of the course of the continuous reaction and to have the starter substance present for the major portion of the copolymerization process. However, incremental addition of DMC catalyst and/or reactant that does not significantly affect the product properties is "continuous" in the sense that the term is used herein. It is possible, for example, to provide a circulation loop in which a portion of the reaction mixture is circulated to a preceding location in the process, thereby eliminating discontinuities caused by incremental addition.

The residence time of the reaction mixture in the reactor is preferably from 0.5 to 5.0 hours, more preferably from 1.0 to 4.0 hours, particularly preferably from 1.5 to 3.5 hours. Residence time is the average residence time in the reactor where thorough mixing is desired.

Step (delta)

In an optional step (δ), the reaction mixture obtained from step (γ), typically having an alkylene oxide content of from 0.05 to 10% by weight, may be subjected to a post-reaction in a reactor or may be continuously transferred to a post-reactor for a post-reaction by which the free alkylene oxide content is reduced. In step (δ), the free alkylene oxide content in the reaction mixture is preferably reduced to less than 0.5 wt.%, more preferably less than 0.1 wt.%, by the post-reaction.

When the reaction mixture obtained from step (γ) remains in the reactor, the reaction mixture is preferably maintained at a temperature of 60 ℃ to 140 ℃ for 10 min to 24 h, more preferably at a temperature of 80 ℃ to 130 ℃ for 1h to 12 h to perform post-reaction. The reaction mixture is preferably stirred here until the free alkylene oxide content in the reaction mixture has been reduced to below 0.5% by weight, more preferably below 0.1% by weight. By having reacted free alkylene oxide and optionally carbon dioxide, the pressure in the reactor during the post-reaction in step (δ) is usually reduced until a constant value is reached.

The post-reactor used may be, for example, a tubular reactor, a loop reactor or a stirred tank. Preferably, the pressure in this latter reactor is the same pressure as in the reaction apparatus in which reaction step (. gamma.) is carried out. However, it is also possible to select a higher or lower pressure in the downstream reactor. In another preferred embodiment, carbon dioxide is released completely or partially after the reaction step (. gamma.) and the downstream reactor is operated at standard pressure or slightly overpressure. The temperature in the downstream reactor is preferably from 50 ℃ to 150 ℃, more preferably from 80 ℃ to 140 ℃.

The post-reactor used is preferably a tubular reactor, wherein, for example, a single tubular reactor or a cascade of a plurality of tubular reactors arranged in parallel or linearly in series can be used. The residence time in the tubular reactor is preferably from 5 min to 10 h, more preferably from 10 min to 5 h.

DMC catalysts

DMC catalysts for the homopolymerization of alkylene oxides are known in principle from the prior art (see, for example, U.S. Pat. No. 3, 3404109, U.S. Pat. No. 3, 3829505, U.S. Pat. No. 3, 3941849 and U.S. Pat. No. 3, 5158922). DMC catalysts such as those described in U.S. Pat. No. 4, 5470813, EP-A700949, EP-A743093, EP-A761708, WO 97/40086, WO 98/16310 and WO 00/47649 have very high activity and enable polyethercarbonate polyols to be prepared at very low catalyst concentrations, so that it is generally no longer necessary to separate the catalyst from the finished product. Typical examples are the highly active DMC catalysts described in EP-A700949, which contain not only double metal cyanide compounds, for example zinc hexacyanocobaltate (III), and organic complexing ligands, for example tert-butanol, but also polyethers having a number average molecular weight of more than 500 g/mol.

The DMC catalyst is preferably obtained by

(i) In a first step an aqueous solution of a metal salt is reacted with an aqueous solution of a metal cyanide salt in the presence of one or more organic complexing ligands, such as ethers or alcohols,

(ii) wherein in a second step the solids are separated from the suspension obtained from (i) by known techniques such as centrifugation or filtration,

(iii) wherein the separated solid is optionally washed with an aqueous solution of the organic complexing ligand in a third step (e.g.by resuspension and subsequent re-separation by filtration or centrifugation),

(iv) wherein the resulting solid is subsequently dried, optionally after powdering, at a temperature of typically 20-120 ℃ and a pressure of typically 0.1 mbar to standard pressure (1013 mbar),

and wherein in the first step or immediately after precipitation of the double metal cyanide compound (second step), one or more organic complexing ligands and optionally further complex-forming components are added, preferably in excess, based on the double metal cyanide compound.

The double metal cyanide compound contained in the DMC catalyst is the reaction product of a water-soluble metal salt and a water-soluble metal cyanide salt.

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

The metal salts suitable for preparing the double metal cyanide compounds preferably have the general formula (II)

M(X)_n (II)

Wherein

M is selected from the metal cations Zn²⁺、Fe²⁺、Ni²⁺、Mn²⁺、Co²+、Sr²⁺、Sn²⁺、Pb²⁺And Cu²⁺(ii) a M is preferably Zn²⁺、Fe² ⁺、Co²⁺Or Ni²⁺，

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

when X = sulfate, carbonate or oxalate, n is 1, and

when X = halide, hydroxide, carboxylate, cyanate, thiocyanate, isocyanate, isothiocyanate or nitrate, n is 2,

or suitable metal salts have the general formula (III)

M_r(X)₃ (III)

Wherein

M is selected from the metal cations Fe³⁺、Al³⁺、Co³⁺And Cr³⁺，

when X = sulfate, carbonate or oxalate, r is 2, and

when X = halide, hydroxide, carboxylate, cyanate, thiocyanate, isocyanate, isothiocyanate or nitrate, r is 1,

or a suitable metal salt having the general formula (IV)

M(X)_s (IV)

Wherein

M is selected from metal cation Mo⁴⁺、V⁴⁺And W⁴⁺，

when X = sulfate, carbonate or oxalate, s is 2, and

when X = halide, hydroxide, carboxylate, cyanate, thiocyanate, isocyanate, isothiocyanate or nitrate, s is 4,

or a suitable metal salt having the formula (V)

M(X)_t (V)

Wherein

M is selected from metal cation Mo⁶⁺And W⁶⁺，

when X = sulfate, carbonate or oxalate, t is 3, and

when X = halide, hydroxide, carboxylate, cyanate, thiocyanate, isocyanate, isothiocyanate or nitrate, t is 6.

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) thiocyanate, nickel (II) chloride and nickel (II) nitrate. Mixtures of different metal salts may also be used.

The metal salts suitable for preparing the double metal cyanide compounds preferably have the general formula (VI)

(Y)_a M'(CN)_b (A)_c (VI)

Wherein

M' is selected from one or more metal cations 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 selected from Co (II), Co (III), Fe (II), Fe (III), Cr (III), Ir (III) and Ni (II),

y is selected from alkali metals (i.e. Li)⁺、Na⁺、K⁺、Rb⁺) And alkaline earth metals (i.e., Be)²⁺、Mg²⁺、Ca²⁺、Sr²⁺、Ba²⁺) One or more metal cations of (a) a,

a is selected from one or more anions of halide (i.e. fluoride, chloride, bromide, iodide), hydroxide, sulfate, carbonate, cyanate, thiocyanate, isocyanate, isothiocyanate, carboxylate, azide, oxalate or nitrate, and

a. b and c are integers, wherein the values of a, b and c are selected to ensure electroneutrality of the metal cyanide salt; a is preferably 1,2,3 or 4; b is preferably 4, 5 or 6; c preferably has a value of 0.

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

Preferred double metal cyanide compounds contained in the DMC catalysts are compounds of the formula (VII)

M_x[M'_x,(CN)_y]_z (VII)

Wherein M is as defined in formulae (II) to (V), and

m' is as defined in formula (VI), and

x, x', y and z are integers and are selected to ensure electroneutrality of the double metal cyanide compound.

It is preferable that

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 hexacyanocoridate (III), zinc hexacyanoferrate (III) and cobalt (II) hexacyanocobaltate (III). Further examples of suitable double metal cyanide compounds can be found, for example, in US 5158922 (column 8, lines 29-66). Particular preference is given to using zinc hexacyanocobaltate (III).

Organic complexing ligands added in the preparation of DMC catalysts are disclosed, for example, in US 5158922 (see, in particular, column 6, lines 9 to 65), US 3404109, US 3829505, US 3941849, EP-A700949, EP-A761708, JP 4145123, US 5470813, EP-A743093 and WO-A97/40086. The organic complexing ligands used are, for example, water-soluble organic compounds containing heteroatoms, such as oxygen, nitrogen, phosphorus or sulfur, which can form complexes with double metal cyanide compounds. Preferred organic complexing ligands are alcohols, aldehydes, ketones, ethers, esters, amides, ureas, nitriles, thioethers and mixtures thereof. Particularly preferred organic complexing ligands are aliphatic ethers (e.g.dimethoxyethane), water-soluble aliphatic alcohols (e.g.ethanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, 2-methyl-3-buten-2-ol and 2-methyl-3-butyn-2-ol), compounds containing aliphatic or cycloaliphatic ether groups and aliphatic hydroxyl groups (e.g.ethylene glycol mono-tert-butyl ether, diethylene glycol mono-tert-butyl ether, tripropylene glycol monomethyl ether and 3-methyl-3-oxetanemethanol). The most preferred organic complexing ligand is selected from one or more of dimethoxyethane, t-butanol, 2-methyl-3-buten-2-ol, 2-methyl-3-butyn-2-ol, ethylene glycol mono-t-butyl ether and 3-methyl-3-oxetanemethanol.

In the preparation of the DMC catalyst, use is optionally made of a catalyst selected from the group consisting of polyethers, polyesters, polycarbonates, polyalkylene glycol sorbitan esters, polyalkylene glycol glycidyl ethers, polyacrylamides, poly (acrylamide-co-acrylic acid), polyacrylic acid, poly (acrylic acid-co-maleic acid), polyacrylonitrile, polyalkyl acrylates, polyalkyl methacrylates, polyvinyl methyl ethers, polyvinyl ethyl ethers, polyvinyl acetates, polyvinyl alcohols, poly-N-vinylpyrrolidone, poly (N-vinylpyrrolidone-co-acrylic acid), polyvinyl methyl ketones, poly (4-vinylphenol), poly (acrylic acid-co-styrene), oxazoline polymers, polyalkylene imines, copolymers of maleic acid and maleic anhydride, hydroxyethyl cellulose and polyacetals, polycarbonates, copolymers of ethylene glycol and propylene glycol, Or one or more complex-forming components of the class of compounds of glycidyl ethers, glycosides, polyol carboxylates, gallic acid (Gallens ä ure) or salts, esters or amides thereof, cyclodextrins, phosphorus compounds, alpha, beta-unsaturated carboxylates or ionic surface-or interface-active compounds.

Preferably, in the DMC catalyst preparation, in a first step an aqueous solution of a metal salt (e.g. zinc chloride) used in a stoichiometric excess (at least 50 mole%) based on the metal cyanide salt (i.e. a molar ratio of metal salt to metal cyanide salt of at least 2.25:1.00) and a metal cyanide salt (e.g. potassium hexacyanocobaltate) is reacted in the presence of an organic complexing ligand (e.g. tert-butanol) to form a suspension comprising a double metal cyanide compound (e.g. zinc hexacyanocobaltate), water, excess metal salt and the organic complexing ligand.

Such organic complexing ligands can be present here in an aqueous solution of the metal salt and/or metal cyanide salt or added directly to the suspension obtained after precipitation of the double metal cyanide compound. It has been found advantageous to mix the aqueous metal salt and metal cyanide salt solutions with the organic complexing ligand by vigorous stirring. Optionally, the suspension formed in the first step is subsequently treated with additional complex-forming components. The complex-forming component is preferably used here in the form of a mixture with water and an organic complexing ligand. The preferred method for carrying out the first step, i.e. the preparation of the suspension, is carried out by using a mixing nozzle, more preferably using a jet disperser as described in WO-a 01/39883.

In a second step, the solid (i.e. the precursor of the catalyst) is separated from the suspension by known techniques, such as centrifugation or filtration.

In a preferred embodiment variant, the isolated solid is subsequently washed in a third process step with an aqueous solution of the organic complexing ligand (for example by resuspension and subsequent re-isolation by filtration or centrifugation). Water-soluble by-products, such as potassium chloride, for example, can thereby be removed from the catalyst. The amount of organic complexing ligand in the aqueous wash solution is preferably from 40 to 80 wt.%, based on total solution.

Optionally, 0.5 to 5 wt.%, preferably based on the total solution, of further complex-forming components are added to the aqueous washing solution in a third step.

It is also advantageous to wash the separated solids more than once. Preferably, in the first washing step (iii-1) an aqueous solution of the organic complexing ligand (e.g. with an aqueous solution of tert-butanol) is washed (e.g. by resuspension and subsequent re-separation by filtration or centrifugation) to thereby remove, for example, water-soluble by-products, such as potassium chloride, from the catalyst. More preferably, the amount of organic complexing ligand (e.g., t-butanol) in the aqueous wash solution is preferably from 40 wt% to 80 wt%, based on the total solution of the first wash step. In a further washing step (iii-2), the first washing step is repeated one or more times, preferably 1 to 3 times, or preferably a non-aqueous solution, for example a mixture or solution of an organic complexing ligand (e.g. tert-butanol) and further complex-forming components (preferably 0.5 to 5% by weight, based on the total amount of washing solution in step (iii-2)) is used as washing solution and the solid is washed one or more times, preferably 1 to 3 times, therewith.

The isolated and optionally washed solid can then be dried, optionally after powdering, at a temperature of 20 to 100 ℃ and a pressure of 0.1 mbar to standard pressure (1013 mbar).

A preferred process for separating the DMC catalyst from the suspension by filtration, cake washing and drying is described in WO-A01/80994.

After carrying out the process according to the invention for preparing polyether carbonate polyols, the reaction mixture obtained comprises the DMC catalyst in the form of generally finely divided solid particles. It may therefore be desirable to remove the DMC catalyst from the resulting reaction mixture as completely as possible. The advantage of separating off the DMC catalyst is, on the one hand, that the polyether carbonate polyols obtained meet industry-or certification-relevant limits, for example with regard to the metal content or with regard to other emissions from the activated catalyst remaining in the product, and, on the other hand, are used for the recovery of the DMC catalyst.

Various methods can be used to substantially or completely remove the DMC catalyst. The DMC catalyst can be separated from the polyethercarbonate polyol, for example, using membrane filtration (nanofiltration, ultrafiltration or crossflow filtration), using cake filtration, using precoat filtration or by centrifugation.

Preferably, the DMC catalyst is separated off using a multistage process consisting of at least two steps.

For example, in the first step, the reaction mixture to be filtered is separated in a first filtration step into a larger substream (filtrate) from which most or all of the catalyst has been separated and a smaller residual stream (retentate) which comprises the separated catalyst. This residual stream is then subjected to dead-end filtration in a second step. A further filtrate stream is thus obtained from which most or all of the catalyst has been separated off, and catalyst residues which are moist to a substantial dryness.

Alternatively, it is also possible to subject the catalyst contained in the polyether carbonate polyol to adsorption, agglomeration/coagulation and/or flocculation in a first step and then to separate the solid phase from the polyether carbonate polyol in a second or more subsequent steps. Adsorbents suitable for mechanical-physical and/or chemical adsorption comprise in particular activated or unactivated alumina or fuller's earth (sepiolite, montmorillonite, talc, etc.), synthetic silicates, activated carbon, silica/diatomaceous earth and activated silica/diatomaceous earth in the typical amount range of 0.1 to 2% by weight, preferably 0.8 to 1.2% by weight, based on the polyether carbonate polyol, at temperatures of 60 to 140 ℃, preferably 90 to 110 ℃, and residence times of 20 to 100 minutes, preferably 40 to 80 minutes, wherein the adsorption step can be carried out in a batch or continuous manner, including the incorporation of the adsorbent.

The preferred method for separating off this solid phase (consisting, for example, of adsorbent and DMC catalyst) from the polyethercarbonate polyol is precoat filtration. Here, the filter surface is "precoated" with a permeable/permeable filter aid (e.g.inorganic: C salts, perlite; organic: cellulose) having a layer thickness of from 20 mm to 250 mm, preferably from 100 mm to 200 mm ("precoating"), depending on the filtration performance which is determined by the particle size distribution of the solid phase to be separated off, the specific average resistance of the filter cake obtained and the total resistance of precoating and filter cake. In combination with the deep filtration of the smaller particles in the precoat, the majority of the solid phase (consisting, for example, of the adsorbent and the DMC catalyst) is separated off at the surface of the precoat. The temperature of the crude product to be filtered is here from 50 ℃ to 120 ℃, preferably from 70 ℃ to 100 ℃.

To ensure adequate product flow through the precoat and cake layer grown thereon, the cake layer and small portions of the precoat layer can be stripped (periodically or continuously) using a scraper or knife and removed from the process. The displacement of such a blade or scraper is performed at a minimum travel speed of about 20-500 μm/min, preferably 50-150 μm/min.

Once the precoat layer is substantially or completely stripped by this method, filtration is stopped and a new precoat layer is applied to the filter surface. The filter aid can be suspended in, for example, cyclic propylene carbonate.

Such precoat filtration is usually carried out in a vacuum drum filter. In order to achieve an industry-related filtrate throughput of 0.1 to 5 m bulkheads/(m.h) with a viscous feed stream, the drum filter may also be manufactured as a pressure drum filter having a pressure difference between the medium to be filtered and the filtrate side of at most 6 bar and more.

In principle, the DMC catalyst can be separated off from the reaction mixture obtained in the process according to the invention either before the removal of volatile constituents (for example cyclic propylene carbonate) or after the separation of volatile constituents.

Furthermore, the DMC catalyst can be separated off from the reaction mixture obtained from the process according to the invention before or during the respective described catalyst separation step, with or without additional addition of solvents, in particular cyclic propylene carbonate, to reduce the viscosity.

Except preferably used zinc (Zn) hexacyanocobaltate bases₃[Co(CN)₆]₂) In addition to the DMC catalysts of (a), the process of the present invention can also be used with other metal complex catalysts based on metallic zinc and/or cobalt and known to the person skilled in the art from the prior art for the copolymerization of epoxides and carbon dioxide. This includes in particular the so-called zinc glutarate catalysts (described for example in m.h. Chisholm et al, Macromolecules 2002, 35, 6494), the so-called zinc diimine catalysts (described for example in s.d. Allen, j. Am. chem.soc.2002, 124, 14284), the so-called cobalt Salen catalysts (described for example in US 7,304,172B 2, US 2012/0165549 a 1) and bimetallic zinc complexes with macrocyclic ligands (described for example in m.r. Kember et al, angelw.chem., int. ed., 2009, 48, 931).

Alkylene oxide

In general, the process of the present invention can use alkylene oxides (epoxides) having from 2 to 24 carbon atoms. Alkylene oxides having 2 to 24 carbon atoms are, for example, selected from the group consisting of ethylene oxide, propylene oxide, 1-butylene oxide, 2, 3-butylene oxide, 2-methyl-1, 2-propylene oxide (isobutylene oxide), 1-pentylene oxide, 2, 3-pentylene oxide, 2-methyl-1, 2-butylene oxide, 3-methyl-1, 2-butylene oxide, 1-hexylene oxide, 2, 3-hexylene oxide, 3, 4-hexylene oxide, 2-methyl-1, 2-pentylene oxide, 4-methyl-1, 2-pentylene oxide, 2-ethyl-1, 2-butylene oxide, 1-heptylene oxide, 1-octylene oxide, 1-nonylene oxide, 1-decylene oxide, 1-epoxyundecane, 1-epoxydodecane, 4-methyl-1, 2-epoxypentane, butadiene monooxide, isoprene monooxide, epoxycyclopentane, epoxycyclohexane, epoxycycloheptane, epoxycyclooctane, styrene oxide, methyl styrene oxide, pinene oxide, mono-or poly-epoxidized fats (in the form of mono-, di-and tri-esters of glycerol), epoxidized fatty acids, C1-C24 esters of epoxidized fatty acids, epichlorohydrin, glycidyl, and glycidyl derivatives such as methyl glycidyl ether, ethyl glycidyl ether, 2-ethylhexyl glycidyl ether, allyl glycidyl ether, glycidyl methacrylate, and epoxy-functional alkoxysilanes such as 3-glycidoxypropyltrimethoxysilane, glycidoxypropylene, glycidol, and the like, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyltripropoxysilane, 3-glycidoxypropyl-methyl-dimethoxysilane, 3-glycidoxypropyl-ethyl-diethoxysilane, and 3-glycidoxypropyltriisopropoxysilane. The alkylene oxide used is preferably ethylene oxide, propylene oxide or a mixture of ethylene oxide and propylene oxide, in particular propylene oxide.

H-functional initiator compounds

According to the invention, a mixture comprising an unactivated double metal cyanide catalyst and an H-functional starter compound is metered in step (γ), wherein the H-functional starter compound is a polyol having a number average molar mass of 550 to 2000 g/mol. The polyols used in the mixtures according to the invention have a functionality of at least 2, preferably from 2 to 8, more preferably from 2 to 4 and particularly preferably from 2 to 3. The number-average molar mass of the polyols is 550 to 2000 g/mol, preferably 600 to 1500 g/mol, particularly preferably 650 to 1250 g/mol, most preferably 700 to 1200 g/mol. The polyol is preferably selected from polyether polyols, polyester polyols, polyesterether polyols, polycarbonate polyols, polyethercarbonate polyols and polyacrylate polyols, more preferably from polyether polyols and polyethercarbonate polyols. The polyols used according to the invention are preferably prepared using DMC catalysts.

In a particularly preferred embodiment, the polyol is selected from the group consisting of molecular weights M_nA polyether polyol having a functionality of from 550 to 2000 g/mol and a molecular weight M of from 2 to 3_nAt least one compound of a polyether carbonate polyol having a functionality of from 2 to 3 in an amount of from 550 to 2000 g/mol, wherein the polyether polyol and the polyether carbonate polyol are most preferably prepared with a DMC catalyst.

In a most preferred embodiment, the polyol is of molecular weight M_nA polyether polyol having a functionality of from 550 to 2000 g/mol and from 2 to 3.

The polyols having a number-average molar mass of 550 to 2000 g/mol may comprise one or more of the compounds mentioned above.

A proportion of activated DMC catalyst may be included in the polyol. The amount of activated DMC catalyst in the polyol used is here preferably 500 ppm or less, more preferably 250 ppm or less, particularly preferably 125 ppm or less, in each case based on the amount of polyol used in the mixture comprising unactivated double metal cyanide catalyst and H-functional starter compound, where the H-functional starter compound is a polyol having a number-average molar mass of 550 to 2000 g/mol.

In a preferred embodiment, the proportion of non-activated DMC catalyst in the mixture comprising non-activated DMC catalyst and polyol having a number average molar mass of 550 to 2000 g/mol is from 50% to 97% by weight, more preferably from 60% to 90% by weight, most preferably from 70% to 80% by weight, in each case based on the sum of the masses of non-activated and activated DMC catalyst.

In addition to polyols having a number average molar mass of 550 to 2000 g/mol, other H-functional starter substances can also be used in the process according to the invention. Suitable further H-functional starter substances ("starters") which can be used are compounds having alkoxylation-active H atoms having a molar mass of from 18 to 4500 g/mol, preferably from 62 to 500 g/mol, more preferably from 62 to 182 g/mol.

Groups reactive for alkoxylation and having active hydrogen atoms are, for example, -OH, -NH₂(Primary amine), -NH- (Secondary amine), -SH and-CO₂H, preferably-OH and-NH₂More preferably-OH. The H-functional starter substances used are, for example, one or more compounds selected from the group consisting of mono-or polyols, polyamines, polythiols, amino alcohols, thiol-containing (Thioalkohol), hydroxy esters, polyether polyols, polyester polyols, polyesterether polyols, polyethercarbonate polyols, polycarbonate, polyethyleneimine, polyetheramine, polytetrahydrofuran (for example PolyTHF from BASF), polytetrahydrofuranamine, polyetherthiols, polyacrylate polyols, castor oil, glycerol mono-or diesters of ricinoleic acid, glycerol monoesters of fatty acids, chemically modified glycerol mono-, di-and/or triesters of fatty acids, and C1-C24 alkyl esters of fatty acids containing on average at least 2 OH groups per molecule. Examples of fatty acid C1-C24 alkyl esters containing an average of at least 2 OH groups per molecule are esters of fatty acids such as Lupranol Balance (from BASF AG), Merginol products (from Hobum Oleo)Chemicals GmbH), Sovermol products (from Cognis Deutschland GmbH)&Co, KG Corp.) and Soyol TM products (from USSC Co.).

The mono-H functional starter compounds used may be alcohols, amines, thiols and carboxylic acids. The monofunctional alcohols used may be: methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, tert-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, 1-tert-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, 2-hydroxy-ethyl-1-ol, 2-butanol, 3-methyl-2-propanol, 1-tert-butoxy-2-propanol, 1-pentanol, 2-pentanol, 3-hexanol, 2-hexanol, 1-heptanol, 2-hydroxy-biphenyl, 2-butanol, or the like, 2-butanol, or the like, 3-hydroxybiphenyl, 4-hydroxybiphenyl, 2-hydroxypyridine, 3-hydroxypyridine, 4-hydroxypyridine. Monofunctional amines that may be considered include: butylamine, tert-butylamine, pentylamine, hexylamine, aniline, aziridine, pyrrolidine, piperidine, morpholine. The monofunctional thiols used may be: ethanethiol, 1-propanethiol, 2-propanethiol, 1-butanethiol, 3-methyl-1-butanethiol, 2-butene-1-thiol, thiophenol. Monofunctional carboxylic acids which may be mentioned include: formic acid, acetic acid, propionic acid, butyric acid, fatty acids such as stearic acid, palmitic acid, oleic acid, linoleic acid, linolenic acid, benzoic acid, acrylic acid.

Examples of polyols suitable as H-functional starter compounds include diols (e.g., ethylene glycol, diethylene glycol, 1, 2-propanediol, dipropylene glycol, 1, 3-propanediol, 1, 4-butanediol, 1, 4-butenediol, 1, 4-butynediol, neopentyl glycol, 1, 5-pentanediol, methylpentanediols (e.g., 3-methyl-1, 5-pentanediol), 1, 6-hexanediol, 1, 8-octanediol, 1, 10-decanediol, 1, 12-dodecanediol, bis- (hydroxymethyl) -cyclohexane (e.g., 1, 4-bis- (hydroxymethyl) cyclohexane), triethylene glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, dibutylene glycol, and polybutylene glycol); trihydric alcohols (e.g. trimethylolpropane, glycerol, trishydroxyethyl isocyanurate, castor oil); tetrahydric alcohols (e.g., pentaerythritol); polyols (e.g., sorbitol, hexitols, sucrose, starch hydrolysates, cellulose hydrolysates, hydroxy-functionalized fats and oils, especially castor oil) and all modifications of these aforementioned alcohols with varying amounts of epsilon-caprolactone.

The H-functional starter compounds can also be selected from the substance classes of polyether polyols having a molecular weight Mn of from 18 to 4500 g/mol and a functionality of from 1 to 8, preferably from 2 to 3. Preferred are polyether polyols made up of repeating ethylene oxide and propylene oxide units, preferably having a proportion of propylene oxide units of from 35% to 100%, more preferably having a proportion of propylene oxide units of from 50% to 100%. These may be random, gradient, alternating or block copolymers of ethylene oxide and propylene oxide.

The H-functional starter compound may also be selected from the substance class of polyester polyols. The polyester polyols used are at least difunctional polyesters. The polyester polyols are preferably composed of alternating acid and alcohol units. The acid component used is, for example, succinic acid, maleic anhydride, adipic acid, phthalic anhydride, phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride or mixtures of the acids and/or anhydrides. The alcohol component used is, for example, ethylene glycol, 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. When the alcohol component used is a binary or a polyhydric polyether polyol, polyester ether polyols are obtained which can likewise be used as starting compounds for the preparation of polyether carbonate polyols.

Furthermore, the H-functional starter compounds used may be, for example, polycarbonate diols prepared by reaction of phosgene, dimethyl carbonate, diethyl carbonate or diphenyl carbonate and difunctional alcohols or polyester polyols or polyether polyols. Examples of polycarbonates can be found, for example, in EP-A1359177.

In another embodiment of the present invention, polyether carbonate polyols may be used as H-functional starter compounds. For this purpose, these polyether carbonate polyols used as H-functional starter compounds are prepared beforehand in a separate reaction step.

The H-functional starter compounds generally have a functionality (i.e. the number of H atoms per molecule that are active for polymerization) of 1 to 8, preferably 2 or 3. The H-functional starter compounds are used alone or as a mixture of at least two H-functional starter compounds.

The H-functional starter compound is particularly preferably one or more compounds selected from the group consisting of ethylene glycol, propane-1, 2-diol, propane-1, 3-diol, butane-1, 4-diol, pentane-1, 5-diol, 2-methylpropane-1, 3-diol, neopentyl glycol, 1, 6-hexanediol, 1, 8-octanediol, diethylene glycol, dipropylene glycol, glycerol, trimethylolpropane, pentaerythritol, sorbitol and polyether polyols having a molecular weight Mn of from 150 to 4500 g/mol and a functionality of from 2 to 3.

Polyether carbonate polyols are prepared by the catalytic addition of carbon dioxide and alkylene oxides onto H-functional starter compounds. In the context of the present invention, "H-functional" is understood to mean the number of H atoms active for alkoxylation per molecule of starter compound.

Component K

Compounds suitable as component K are characterized in that they contain at least one phosphorus-oxygen-hydrogen bond. Preferably, component K is at least one compound selected from the group consisting of:

phosphoric acid,

Mono-and dialkyl esters of phosphoric acid,

Mono-and diaryl esters of phosphoric acid,

Mono-and dialkyl aryl esters of phosphoric acid,

(NH₄)₂HPO₄，

Phosphonic acid,

Monoalkyl esters of phosphonic acids,

A monoaryl ester of a phosphonic acid,

Monoalkylaryl esters of phosphonic acids,

Phosphorous acid,

Mono-and dialkyl esters of phosphorous acid,

Mono-and diaryl phosphites,

Mono-and dialkyl aryl esters of phosphorous acid, and

phosphinic acid.

The mono-or dialkyl esters of phosphoric acid are preferably mono-and dialkyl esters of orthophosphoric acid, mono-, di-or trialkyl esters of pyrophosphoric acid and mono-, di-, tri-, tetra-or polyalkyl esters of polyphosphoric acid, more preferably the respective esters comprising alcohols having from 1 to 30 carbon atoms. The mono-or diaryl esters of phosphoric acid are preferably mono-and diaryl esters of orthophosphoric acid, mono-, di-or triaryl esters of pyrophosphoric acid and mono-, di-, tri-, tetra-or polyaryl esters of polyphosphoric acid, more preferably the respective esters comprising alcohols having from 6 to 10 carbon atoms. The mono-or dialkyl aryl esters of phosphoric acid are preferably mono-or dialkyl aryl esters of orthophosphoric acid, mono-, di-or trialkyl aryl esters of pyrophosphoric acid and mono-, di-, tri-, tetra-or polyalkyl aryl esters of polyphosphoric acid, more preferably the respective esters comprising alcohols having from 7 to 30 carbon atoms. Examples of compounds suitable as component K include the following: diethyl phosphate, monoethyl phosphate, dipropyl phosphate, monopropyl phosphate, dibutyl phosphate, monobutyl phosphate, diphenyl phosphate, ditolyl phosphate, fructose 1, 6-diphosphate, glucose 1-phosphate, bis (4-nitrophenyl) phosphate, dibenzyl phosphate, diethyl 3-butenyl phosphate, dihexadecyl phosphate, diphenyl phosphate, and 2-hydroxyethyl methacrylate phosphate.

The monoalkyl esters of phosphonic acids preferably used are the respective esters comprising alcohols having from 1 to 30 carbon atoms. The monoaryl esters of phosphonic acids preferably used are the respective esters comprising alcohols having from 6 to 10 carbon atoms. The monoalkylaryl esters of phosphonic acids preferably used are the respective esters comprising alcohols having from 7 to 30 carbon atoms.

The mono-and dialkyl esters of phosphorous acid preferably used are the respective esters comprising alcohols having from 1 to 30 carbon atoms. This includes, for example, phenylphosphonic acid, butylphosphonic acid, dodecylphosphonic acid, ethylhexylphosphonic acid, octylphosphonic acid, ethylphosphonic acid, methylphosphonic acid and octadecylphosphonic acid. The mono-and diaryl esters of phosphorous acid preferably used are the respective esters comprising alcohols having from 6 to 10 carbon atoms. The mono-and dialkyl aryl phosphites which are preferably used are the respective esters comprising alcohols having from 7 to 30 carbon atoms.

Component K is more preferably at least one compound selected from phosphoric acid, phosphonic acid and phosphinic acid. Component K is most preferably phosphoric acid.

Alcohols having 1 to 30 carbon atoms mentioned in the description of component K are, for example, methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol, heptadecanol, octadecanol, nonadecanol, methoxymethanol, ethoxymethanol, propoxymethanol, butoxymethanol, 2-ethoxyethanol, 2-propoxyethanol, 2-butoxyethanol, phenol, ethyl glycolate, propyl glycolate, ethyl hydroxypropionate, propyl hydroxypropionate, 1, 2-ethanediol, 1, 2-propanediol, 1,2, 3-trihydroxypropane, 1,1, 1-trimethylolpropane or pentaerythritol.

Also suitable as component K are phosphorus compounds which can form one or more phosphorus-oxy-hydrogen groups by reaction with OH-functional compounds, for example water. Examples of such phosphorus compounds that may be considered include phosphorus (V) sulfide, phosphorus tribromide, phosphorus trichloride, and phosphorus triiodide.

Mixtures of any of the above compounds can also be used as component K. Component K can also be used in a mixture with a suspending agent or in a mixture with a trialkyl phosphate, in particular triethyl phosphate.

In a preferred embodiment, component K is selected from phosphoric acid, phosphonic acid, phosphorous acid, phosphinic acid, phosphonous acid, phosphinic acid, phosphine oxides and at least one compound of phosphoric acid, phosphonic acid, phosphorous acid, phosphinic acid, phosphonous acid, phosphinic acid salts, esters, halides and amides, phosphorus (V) sulfide, phosphorus tribromide, phosphorus trichloride and phosphorus triiodide.

Component K can be metered in at any stage of the process, component K preferably being metered in such a way that the reaction product obtained from stage (γ) contains an amount of from 5 to 2000 ppm, more preferably from 10 to 1000 ppm, particularly preferably from 30 to 500 ppm. It is advantageous to meter in component K in step (γ); particularly preferably, component K is metered in admixture with the H-functional starter compound. It is also advantageous to add component K to the reaction mixture in the postreactor of step (δ). It is furthermore advantageous to add component K to the reaction mixture obtained after the post-reaction (step (. delta.)).

In a preferred embodiment, the polyol in the mixture of step (γ) contains component K in a proportion of from 5 to 2000 ppm, wherein said component K is selected from the group consisting of phosphoric acid, phosphonic acid, phosphorous acid, phosphinic acid, phosphonous acid, phosphinic acid, phosphine oxide and at least one compound of phosphoric acid, phosphonic acid, phosphorous acid, phosphinic acid, phosphonous acid, salts, esters, halides and amides of phosphinic acid, phosphorous sulfide (V), phosphorous tribromide, phosphorous trichloride and phosphorous triiodide.

In one possible embodiment of the present invention, during the post-reaction (step (δ)), component K is added in an amount of from 5 ppm to 1000 ppm, more preferably from 10 ppm to 500 ppm, most preferably from 20 ppm to 200 ppm, in each case based on the reaction mixture obtained in step (γ). Component K is more preferably added during the post-reaction at a free alkylene oxide content of from 0.1 to 10% by weight, most preferably from 1 to 10% by weight, most particularly preferably from 5 to 10% by weight, of alkylene oxide. When the process of the invention is carried out using a tubular reactor for the post-reaction in step (δ), component K is more preferably metered in the second half of the passage of the reaction mixture in the tubular reactor.

The polyether carbonate polyols obtained according to the present invention have a functionality of, for example, at least 2, preferably from 2 to 8, more preferably from 2 to 6, most preferably from 2 to 4. The molecular weight is preferably from 800 to 10000 g/mol, more preferably from 1200 to 6000 g/mol.

The polyether carbonate polyols obtainable by the process of the present invention have a low content of by-products and can be processed without difficulty, in particular by reaction with di-and/or polyisocyanates, to give polyurethanes, in particular polyurethane flexible foams. For polyurethane applications, preference is given to using polyether carbonate polyols based on H-functional starter compounds having a functionality of at least 2.

Furthermore, the polyether carbonate polyols obtainable by the process of the present invention can also be used in applications such as washing and cleaning composition formulations, drilling fluids, fuel additives, ionic and nonionic surfactants, lubricants, technical chemicals for paper or textile manufacture or cosmetic formulations.

It is known to the person skilled in the art that, depending on the respective field of application, the polyether carbonate polyols used must meet certain material properties, such as molecular weight, viscosity, functionality and/or hydroxyl number.

Examples

The present invention is illustrated in detail by the following examples, but is not limited thereto.

The DMC catalyst used in the examples was prepared according to example 6 of WO-A01/80994.

The pressure data refers to absolute pressure.

GPC：

Number average molecular weight M of the product_nAnd a weight average molecular weight M_wAnd polydispersity (M)_w/M_n) As determined by Gel Permeation Chromatography (GPC). Operating according to DIN 55672-1 (2016 month 3): "gel permeation chromatography, part 1-tetrahydrofuran as eluent" (SECURITY GPC System from PSS Polymer Service, flow rate 1.0 ml/min; column: 2 XPSS SDV Linear M, 8X 300 mm, 5 μ M; RID detector). Here, polystyrene samples of known molar mass are used for calibration.

CO in polyether carbonate polyols₂The contents are as follows:

CO incorporated in the polyether carbonate polyol obtained₂And the ratio of propylene carbonate to polyether carbonate polyol are determined by¹H-NMR (Bruker, DPX 400, 400 Mhz; pulse program zg30, relaxation delay d1: 10s, 64 scans). Each sample was dissolved in deuterated chloroform.¹The relevant resonances in H NMR (based on TMS = 0 ppm) were as follows:

cyclic carbonates with resonances at 4.5 ppm (which are formed as by-products), carbonates produced from carbon dioxide incorporated into the polyether carbonate polyol with resonances at 5.1 to 4.8 ppm, unreacted PO with resonances at 2.4 ppm, polyether polyols with resonances at 1.2 to 1.0 ppm (i.e. without incorporated carbon dioxide), 1, 8-octanediol incorporated as starter molecule (if present) with resonances at 1.6 to 1.52 ppm.

The molar proportion of carbonate incorporated into the polymer in the reaction mixture is calculated as follows according to formula (VIII), using the following abbreviations:

f (4.5) = resonance area at 4.5 ppm of cyclic carbonate (corresponding to one H atom)

F (5.1-4.8) = area of resonance of one H atom of polyether carbonate polyol and cyclic carbonate at 5.1-4.8 ppm

F (2.4) = resonance area of free unreacted PO at 2.4 ppm

F (1.2-1.0) = resonance area of polyether polyol under 1.2-1.0 ppm

F (1.6-1.52) = 1, 8-octanediol (starter) (if present) area of resonance at 1.6 to 1.52 ppm.

Taking into account the relative strength, the polymerization-bonded carbonate ("linear carbonate" LC) in the reaction mixture is converted to mol% according to the following formula (VIII):

。

the weight proportion (% by weight) of the polymerically bonded carbonate (LC') in the reaction mixture is calculated on the basis of the formula (IX):

wherein the value of N ("denominator" N) is calculated according to formula (X):

。

factor 102 is obtained from CO₂The sum of the molar masses of (molar mass 44 g/mol) and of propylene oxide (molar mass 58 g/mol); the factor 58 is obtained from the molar mass of propylene oxide; and the factor 146 is obtained from the molar mass of the 1, 8-octanediol starter used, if present.

The weight proportion (% by weight) of the cyclic carbonate (CC') in the reaction mixture is calculated according to formula (XI):

wherein the value of N is calculated according to equation (X).

In order to calculate the composition based on the polymer fraction (from the polyether polyol (which is free of CO) from the composition value of the reaction mixture₂Formed from starter and propylene oxide during the activation step carried out under conditions) and polyether carbonate polyols (which are in CO₂Formed by the starter, propylene oxide and carbon dioxide during the activation step carried out in the presence and during the copolymerization), the non-polymeric constituents of the reaction mixture (i.e. the cyclic propylene carbonate and optionally unconverted propylene oxide) are excluded by calculation. The weight proportion of the carbonate repeating units in the polyether carbonate polyol is converted to the weight proportion of carbon dioxide using a factor F =44/(44+ 58). CO in polyether carbonate polyols₂The data on the content is normalized to that in CO₂The proportion of polyether carbonate polyol molecules formed in the copolymerization and optional activation step in the presence (i.e.obtained from the starter (1, 8-octanediol, if present) and from the starter to the reaction mixture in the absence of CO₂The proportion of polyether carbonate polyol molecules obtained by reaction of the epoxide added under the conditions is not taken into account here).

Example 1: propylene oxide and CO Using unactivated DMC catalyst₂By copolymerization of

Preparation of catalyst-polyol mixture 1

In a first vessel, 6.108 g of DMC catalyst (not activated) and 170 ppm H₃PO₄(85%) was mixed into 10 kg of a poly (oxypropylene) polyol having a number average molar mass of 683 g/mol and a functionality of 2.8. The poly (oxypropylene) polyol already contained 65 ppm of activated DMC catalyst.

Step (alpha)

A pressure reactor purged with nitrogen and having a gas metering device (gas inlet line) and a product discharge line was preloaded with 0.83 g of DMC catalyst (not activated) and 5 kg of number averageA molar mass of 2914 g/mol, a functionality of 2.8 and CO₂A suspension of polyether carbonate polyol with a content of 14.6%.

Step (beta)

By addition of CO₂The reactor was adjusted to a pressure of 30 bar and correspondingly to 120 ℃. 0.25 kg of Propylene Oxide (PO) was metered into the reactor over the course of 2 min with stirring at 120 ℃. The reaction start is indicated by a temperature peak ("hot spot"). A second addition of 0.25 kg of propylene oxide was made within 2 min. The reaction start is again indicated by a temperature peak.

Step (gamma)

After activation was complete, the reactor contents were tempered to 120 ℃. Thereafter, 7.7 kg/h of propylene oxide, 2.7 kg/h of catalyst-polyol mixture 1 and carbon dioxide were metered simultaneously into the reactor, so that a residence time of 2.5 h and a total pressure of 30 bar were produced in the steady-state continuous operation of the stirred reactor. The concentration of free propylene oxide in the steady-state continuous state (measured in the reactor by means of the MIR probe) is here 1.1% by weight and the reaction temperature is 107 ℃. The catalyst concentration in the reactor was 100 ppm.

Step (delta)

Thereafter, the reaction mixture was conveyed from the pressure reactor through a tubular postreactor (reaction volume 2 l) which was tempered to 120 ℃. The surge tank was operated at 120 ℃ and an average residence time of 4 h before the cyclic propylene carbonate was separated off.

Finally, in order to isolate the cyclic propylene carbonate, the product is subjected to a two-step thermal after-treatment, i.e. in a first step by means of a falling-film evaporator and then in a second step by means of a stripper operating under nitrogen countercurrent.

The falling-film evaporator is operated here at a temperature of 169 ℃ and a pressure of 17 mbar (absolute).

The nitrogen stripper was operated at a temperature of 160 ℃, a pressure of 80 mbar (abs.) and 0.6 kg N₂Run under nitrogen flow per kg product.

Example 2: propylene oxide using unactivated DMC catalystsAnd CO₂By copolymerization of

The process in example 2 is carried out analogously to example 1, the residence time in the steady-state continuous operation of the stirred reactor in step (. gamma.) being 1.7 h.

Example 3: propylene oxide and CO Using unactivated DMC catalyst₂By copolymerization of

The process in example 2 is carried out analogously to example 1, the residence time in the steady-state continuous operation of the stirred reactor in step (. gamma.) being 1.4 hours.

Example 4 (comparative): propylene oxide and CO Using activated DMC catalysts₂By copolymerization of

Preparation of catalyst-polyol mixture 2

In the first reactor, 4.476 g of DMC catalyst (unactivated) were mixed into 10 kg of a poly (oxypropylene) polyol having a number average molar mass of 716 g/mol and a functionality of 2.8. The poly (oxypropylene) polyol is tempered to 100 ℃ and N is added₂Stripping was continued at 10 mbar for 60 min. Thereafter, the vessel contents were tempered to 130 ℃ and CO was added thereto₂A pressure of 30 bar was established. With the addition of 2.9 kg of propylene oxide, the catalyst was activated, which is indicated by a temperature peak. This activation step was repeated two more times, with each passage of a temperature peak indicating the start of the reaction. 170 ppm of H₃PO₄(85%) was added to catalyst-polyol mixture 2.

Step (alpha)

A pressure reactor inerted with nitrogen, having a gas metering device (gas inlet line) and a product discharge line, was preloaded with 0.5 g of DMC catalyst (unactivated) and 5 kg of a number-average molar mass of 2914 g/mol, a functionality of 2.8 and CO₂A suspension of polyether carbonate polyol with a content of 14.6%.

Step (beta)

By addition of CO₂The reactor was adjusted to a pressure of 30 bar and correspondingly to 120 ℃. 0.225 kg of Propylene Oxide (PO) was metered into the reactor at 120 ℃ over the course of 2 min with stirring. Passing the temperature peak("hot spot") indicates the start of the reaction. A second addition of 0.225 kg of Propylene Oxide (PO) was made within 2 min. The reaction start is again indicated by a temperature peak ("hot spot").

Step (gamma)

After activation was complete, the reactor contents were tempered to 120 ℃. Thereafter, 6.6 kg/h of propylene oxide, 3.45 kg/h of catalyst-polyol mixture 2 and carbon dioxide were metered simultaneously into the reactor, so that a residence time of 2.9 h and a pressure of 30 bar were produced in the steady-state continuous operation of the stirred reactor. The catalyst concentration in the reactor was 100 ppm. The temperature should here be reduced stepwise to the target value of 112 ℃, but when 6 hours after the reduction to 114 ℃, a free propylene oxide concentration of more than 5% (measured in the reactor by the MIR probe) is established, so that it is no longer possible to run a stable process due to significant temperature and pressure fluctuations. After this time, the free propylene oxide concentration was slowly reduced and the experiment was restarted at 120 ℃ and the temperature was gradually reduced to 117 ℃ at which steady state operation was continued. The concentration of propylene oxide leaving the reactor (measured by the MIR probe in the reactor) at steady state was here 3.8 wt.%. For reasons of process stability, it is not possible to increase the throughput to shorten the residence time in the main reactor. In each case, the reaction mixture was continuously withdrawn from the reactor via a product discharge line.

Step (delta)

To complete the reaction, the reaction mixture was conveyed through a tubular reactor, which was tempered to 120 ℃. Before separation, the buffer tank was operated at 120 ℃ and an average residence time of 4 h. In analogy to the procedure in examples 1 to 3, cyclic propylene carbonate was separated from polyether carbonate polyol.

Example 5 (comparative): propylene oxide and CO Using short chain Starter₂Copolymerization of (2)

Preparation of catalyst-polyol mixture 3

In the first reactor, 26.5 g of DMC catalyst (not activated) were mixed into 5 kg of a mixture of glycerol (4.25 kg) and propylene glycol (0.75% by weight), which corresponds to a mixture of 2.8Functionality. 170 ppm of H₃PO₄(85%) was added to the catalyst-polyol mixture 3.

Step (alpha)

A pressure reactor inerted with nitrogen, having a gas metering device (gas inlet line) and a product discharge line, was preloaded with 1 g of DMC catalyst (not activated) and 4.7 kg of a suspension of propylene carbonate.

Step (beta)

By addition of CO₂The reactor was adjusted to a pressure of 30 bar and correspondingly to 120 ℃. 0.225 kg of Propylene Oxide (PO) was metered into the reactor at 120 ℃ over the course of 2 min with stirring. The reaction start is indicated by a temperature peak ("hot spot"). A second addition of 0.225 kg of Propylene Oxide (PO) took place within 2 min. The reaction start is again indicated by a temperature peak ("hot spot").

Step (ii) of(γ)

After activation was complete, the reactor contents were tempered to 120 ℃. Thereafter, 7.4 kg/h of propylene oxide, 0.26 kg/h of catalyst-polyol mixture 3 and carbon dioxide were metered simultaneously into the reactor, so that a residence time of 3.8 h and a pressure of 30 bar were produced in the steady-state continuous operation of the stirred reactor. The catalyst concentration in the reactor was 150 ppm. The temperature is here gradually reduced to a target value of 107 ℃. The concentration of propylene oxide leaving the reactor (measured by the MIR probe in the reactor) at steady state was here 2.4 wt.%. In each case, the reaction mixture was continuously withdrawn from the reactor via a product discharge line.

Step (delta)

Table 1:

	residence time [ h ]]	Incorporated CO₂[ weight% ]]	PDI [Mw/Mn]	Selective c/l [ -]	Concentration of free PO [ wt.%]
						Example 1	2.5	13.2	1.11	0.08	1.1
Example 2	1.7	12.6	1.11	0.08	2.0
						Example 3	1.4	12.3	1.12	0.08	2.2
Example 4	2.9	12.6	1.69	0.107	3.8
						Example 5	3.8	14.7	1.12	0.165	2.4

Comparative example

Cyclic carbonate/linear carbonate ratio.

Claims

1. A process for preparing polyether carbonate polyols comprising the step of reacting an alkylene oxide with carbon dioxide in the presence of an H-functional starter compound and a double metal cyanide catalyst, characterized in that:

2. The process according to claim 1, characterized in that the reaction product obtained from step (γ) is continuously withdrawn from the reactor.

3. The process according to claim 2, characterized in that the average residence time of the reaction mixture in step (γ) is from 0.5 to 5.0 hours.

4. The process according to claim 2, characterized in that the average residence time of the reaction mixture in step (γ) is from 1.5 to 5.0 hours.

5. Process according to any one of claims 1 to 4, characterized in that the mixture comprising the unactivated double metal cyanide catalyst and the H-functional starter compound contains 500 ppm or less of activated double metal cyanide catalyst based on the H-functional starter compound.

6. Process according to any of claims 1 to 5, characterized in that in the mixture comprising non-activated DMC catalyst and H-functional starter compound, the proportion of non-activated DMC catalyst is from 50% to 97% by weight, based on the sum of the masses of non-activated and activated DMC catalyst in the mixture.

7. Process according to any one of claims 1 to 6, characterized in that component K is added so that component K is contained in the reaction product obtained from step (γ) in a proportion of 5 to 2000 ppm.

8. A process according to claim 7, characterized in that component K is selected from phosphoric acid, phosphonic acid, phosphorous acid, phosphinic acid, phosphonous acid, phosphinic acid, phosphine oxide and at least one compound of phosphoric acid, phosphonic acid, phosphorous acid, phosphinic acid, phosphonous acid, phosphinic acid salts, esters, halides and amides, phosphorus (V) sulfide, phosphorus tribromide, phosphorus trichloride and phosphorus triiodide.

9. Process according to any one of claims 1 to 7, characterized in that the polyol in the mixture of step (γ) contains component K in a proportion of from 5 to 2000 ppm, wherein said component K is selected from phosphoric acid, phosphonic acid, phosphorous acid, phosphinic acid, phosphonous acid, phosphinic acid, phosphine oxide and at least one compound of phosphoric acid, phosphonic acid, phosphorous acid, phosphinic acid, phosphonous acid, phosphinic acid salts, esters, halides and amides, phosphorus sulfide (V), phosphorus tribromide, phosphorus trichloride and phosphorus triiodide.

10. Process according to any one of claims 1 to 9, characterized in that the polyol in the mixture of step (γ) has a number average molar mass according to DIN 55672-1 of from 600 to 1500 g/mol.

11. The process according to any one of claims 1 to 10, characterized in that the polyol in the mixture of step (γ) is selected from at least one compound of the group consisting of polyether polyols, polyester polyols, polyesterether polyols, polycarbonate polyols, polyethercarbonate polyols and polyacrylate polyols.

12. The process as claimed in any of claims 1 to 9, characterized in that the H-functional starter compound in the mixture comprising the unactivated double metal cyanide catalyst and the H-functional starter compound of step (γ) is selected from the group consisting of molecular weights M according to DIN 55672-1_nA polyether polyol having a functionality of from 550 to 2000 g/mol and a molecular weight M of from 2 to 3_nAt least one compound of a polyether carbonate polyol having a functionality of from 2 to 3 and from 550 to 2000 g/mol.

13. Process according to any one of claims 1 to 12, characterized in that the double metal cyanide catalyst is present in step (γ) in a proportion of 10 to 10000 ppm, based on the entire reaction mixture.

14. A process according to any one of claims 1 to 13, characterized in that the alkylene oxide used is ethylene oxide, propylene oxide or a mixture of propylene oxide and ethylene oxide.

15. A process according to any one of claims 1 to 14, characterized in that the double metal cyanide catalyst used comprises at least one compound selected from the group consisting of zinc hexacyanocobaltate (III), zinc hexacyanoferrate (III) and cobalt (II) hexacyanocobaltate (III).