Use of urethane alcohols for preparing polyether carbonate polyols

Abstract

The present invention relates to a method for preparing polyether carbonate polyols by the addition of alkylene oxides and carbon dioxide onto H-functional starter compounds. The method is characterized in that at least one urethane alcohol according to formula (II) is used as an H-functional starter compound, wherein R 1 represents a linear or branched C2 to C24-alkylene which can be optionally interrupted by heteroatoms such as O, S or N and can be substituted; R2 represents a linear or branched C2 to C24-alkylene which can be optionally interrupted by heteroatoms such as O, S or N and can be substituted; R3 represents H, linear or branched C1 to C24-alkyl, C3 to C24-cycloalkyl, C4 to C24-aryl, C5 to C24-arylalkyl, C2 to C24-alkenyl, C2 to 24-alkinyl, that can each be optionally interrupted by heteroatoms such as O, S, or N and/or may each be substituted with alkyl, aryl, and/or hydroxyl.

Claims

1. A process for preparing polyether carbonate polyols, the process comprising an addition of alkylene oxides and carbon dioxide onto H-functional starter compounds comprising at least one urethane alcohol of formula (II) ##STR00004## where R.sup.1 is linear or branched C.sub.2- to C.sub.24-alkylene which may optionally be interrupted by heteroatoms such as O, S or N and may be substituted, R.sup.2 is linear or branched C.sub.2- to C.sub.24-alkylene which may optionally be interrupted by heteroatoms such as O, S or N and may be substituted, R.sup.3 is H, linear or branched C.sub.1- to C.sub.24-alkyl, C.sub.3- to C.sub.24-cycloalkyl, C.sub.4- to C.sub.24-aryl, C.sub.5- to C.sub.24-aralkyl, C.sub.2- to C.sub.24-alkenyl, C.sub.2- to C.sub.24-alkynyl, each of which may optionally be interrupted by heteroatoms such as O, S or N and/or each of which may be substituted by alkyl, aryl and/or hydroxyl.

2. The process as claimed in claim 1, wherein R.sup.1=CH.sub.2CH.sub.2 or CH.sub.2CH(CH.sub.3), R.sup.2=CH.sub.2CH.sub.2 or CH.sub.2CH(CH.sub.3), and R.sup.3=H.

3. The process as claimed in claim 1, wherein the urethane alcohol of formula (II) is obtained by reacting propylene carbonate and/or ethylene carbonate with an alkanolamine of formula (III)
HN(R.sup.3)R.sup.2OH(III)

4. The process as claimed in claim 3, wherein the urethane alcohol is obtained by reacting propylene carbonate and/or ethylene carbonate with at least one amine selected from the group consisting of ethanolamine, diethanolamine, (N-methyl)ethanolamine, isopropanolamine, diisopropanolamine and propanolamine.

5. The process as claimed in claim 1, wherein the alkylene oxide used is at least one alkylene oxide selected from the group consisting of ethylene oxide and propylene oxide.

6. The process as claimed in claim 1, wherein the addition is conducted in the presence of at least one DMC catalyst.

7. The process as claimed in claim 1, wherein the addition is conducted in the presence of a metal complex catalyst based on the metals zinc and/or cobalt.

8. The process as claimed in claim 1, wherein () the urethane alcohol of formula (II) or a suspension medium is initially charged and any water and/or other volatile compounds are removed by elevated temperature and/or reduced pressure, with addition of the DMC catalyst to the urethane alcohol of formula (II) or to the suspension medium before or after the removal of the water and/or the other volatile compounds, and () adding a portion to activate copolymerization (based on the total amount of alkylene oxides used in the activation and copolymerization) of alkylene oxide to the mixture resulting from step (), where this portion of alkylene oxide may optionally be added in the presence of CO.sub.2 and where a temperature spike that occurs due to the exothermic chemical reaction that follows and/or a pressure drop in the reactor is awaited in each case, and where step () for activation may also be repeated, and () adding alkylene oxide, carbon dioxide and optionally urethane alcohol of formula (II) to the mixture resulting from step (), where at least one urethane alcohol of formula (II) is added as H-functional starter substance at least in one of steps () and ().

9. The process as claimed in claim 1, wherein one or more urethane alcohols of the formula (II) are metered continuously into a reactor as H-functional starter substance(s) during the addition.

10. The process as claimed in claim 6, wherein the one or more urethane alcohols of formula (II), the one or more alkylene oxide(s) and the DMC catalyst are metered continuously into a reactor in the presence of the carbon dioxide and wherein the resulting reaction mixture, which includes the reaction product of the copolymerization, is removed continuously from the reactor.

11. The process as claimed in claim 10, wherein, in a step (), the reaction mixture removed continuously from the reactor with a content of 0.05% by weight to 10% by weight of alkylene oxide is transferred into a postreactor in which, by way of a postreaction, the content of free alkylene oxide is reduced to less than 0.05% by weight in the reaction mixture.

12. A polyurethane foam prepared by reacting a polyisocyanate with a polyether carbonate polyol containing a structural unit of the formula (IV) ##STR00005## where R.sup.1=CH.sub.2CH.sub.2 or CH.sub.2CH(CH.sub.3), R.sup.2=CH.sub.2CH.sub.2 or CH.sub.2CH(CH.sub.3), and where R.sup.1 and R.sup.2 may be identical or different from one another.

Description

EXAMPLES

(1) Test Methods:

(2) Experimentally determined OH numbers were determined by the method of DIN 53240. The amine numbers (NH number) were determined by the method of DIN 53176.

(3) The viscosities were determined by means of a rotary viscometer (Physica MCR 51, manufacturer: Anton Paar) by the method of DIN 53018.

(4) The fraction of incorporated CO.sub.2 in the resulting polyether carbonate polyol (CO.sub.2 content) and the ratio of propylene carbonate to polyether carbonate polyol were determined by .sup.1H NMR (Bruker DPX 400, 400 MHz; pulse program zg30, relaxation delay d1: 10 s, 64 scans). Each sample was dissolved in deuterated chloroform. The relevant resonances in the .sup.1H NMR (based on TMS=0 ppm) are as follows:

(5) cyclic carbonate (which was formed as a by-product) resonance at 4.5 ppm, carbonate resulting from carbon dioxide incorporated in the polyether carbonate polyol (resonances at 5.1 to 4.8 ppm), unreacted PO with resonance at 2.4 ppm, polyether polyol (i.e. without incorporated carbon dioxide) having resonances at 1.2 to 1.0 ppm.

(6) The mole fraction of the carbonate incorporated in the polymer in the reaction mixture is calculated by formula (XIV) as follows, using the following abbreviations:

(7) A(4.5)=area of the resonance at 4.5 ppm for cyclic carbonate (corresponds to a hydrogen atom)

(8) A(5.1-4.8)=area of the resonance at 5.1-4.8 ppm for polyether carbonate polyol and a hydrogen atom for cyclic carbonate

(9) A(2.4)=area of the resonance at 2.4 ppm for free, unreacted PO

(10) A(1.2-1.0)=area of the resonance at 1.2-1.0 ppm for polyether polyol

(11) Taking into account the relative intensities the values for the polymer-bound carbonate (linear carbonate LC) in the reaction mixture were converted into mol % as per the following formula (XII):

(12) $\begin{array}{cc}\mathrm{LC}=\frac{A\left(5.1-4.8\right)-A\left(4.5\right)}{A\left(5.1-4.8\right)+A\left(2.4\right)+0.33*A\left(1.2-1.0\right)}*100& \left(\mathrm{XII}\right)\end{array}$

(13) The weight fraction (in % by weight) of polymer-bound carbonate (LC) in the reaction mixture was calculated by formula (XIII),

(14) $\begin{array}{cc}{\mathrm{LC}}^{}=\frac{\left[A\left(5.1-4.8\right)-A\left(4.5\right)\right]*102}{D}*100\%& \left(\mathrm{XIII}\right)\end{array}$

(15) where the value of D (denominator D) is calculated by formula (XIV):
D=[A(5.1-4.8)A(4.5)]*102+A(4.5)*102+A(2.4)*58+0.33*A(1.2-1.0)*58(XIV)

(16) The factor of 102 results from the sum of the molar masses of CO.sub.2 (molar mass 44 g/mol) and of propylene oxide (molar mass 58 g/mol); the factor of 58 results from the molar mass of propylene oxide.

(17) The weight fraction (in % by weight) of cyclic carbonate (CC) in the reaction mixture was calculated by formula (XI):

(18) $\begin{array}{cc}{\mathrm{CC}}^{}=\frac{A\left(4.5\right)*102}{D}*100\%& \left(\mathrm{XV}\right)\end{array}$

(19) where the value of D is calculated by formula (XIV).

(20) In order to calculate the composition based on the polymer component (consisting of polyether which has been formed from propylene oxide during the activation steps which take place under CO.sub.2-free conditions, and polyether carbonate polyol formed from starter, propylene oxide and carbon dioxide during the activation steps which take place in the presence of CO.sub.2 and during the copolymerization) from the values for the composition of the reaction mixture, the non-polymeric constituents of the reaction mixture (i.e. cyclic propylene carbonate and any unconverted propylene oxide present) were mathematically eliminated. The weight fraction of the repeat carbonate units in the polyether carbonate polyol was converted to a weight fraction of carbon dioxide using the factor A=44/(44+58). The figure for the CO.sub.2 content in the polyether carbonate polyol (CO.sub.2 incorporated; see examples which follow and table 1) is normalized to the polyether carbonate polyol molecule which has formed in the copolymerization and the activation steps.

(21) The amount of cyclic propylene carbonate formed is determined via the mass balance of the total amount of cyclic propylene carbonate present in the reaction mixture and the amount of propylene carbonate used as the initial charge.

(22) The determination of the functionality of the starter in the finished polyether carbonate polyol was conducted by means of .sup.13C NMR (from Bruker, Advance 400, 400 MHz; wait time d1: 4 s, 6000 scans). Each sample was dissolved in deuterated acetone-D6 with addition of chromium(III) acetylacetonate. The solution concentration was 500 mg/mL.

(23) The relevant resonances in the .sup.13C NMR (based on CHCl.sub.3=7.24 ppm) are as follows:

(24) The carbon signals of the carbon atoms bonded directly to the nitrogen (methylene groups, methine group) of the starter are evaluated:

(25) Bifunctionally started: 40.4 ppm to 40.0 ppm (one carbon)

(26) Trifunctionally started: 42.2 ppm to 40.5 ppm (two carbons)

(27) Bifunctionally started means that only the OH groups of the urethane alcohol starter compound are alkoxylated.

(28) Trifunctionally started means that the OH groups and the NH group of the urethane bond of the urethane alcohol starter compound are alkoxylated.

(29) The chemical shifts in the .sup.13C NMR were determined by comparative measurements (comparative spectra).

(30) The apparent densities were determined to DIN EN ISO 845.

(31) The compression hardnesses (40% compression) were determined to DIN EN ISO 1798.

(32) Raw Materials Used:

(33) Catalyst for the preparation of the polyether carbonate polyols (DMC catalyst):

(34) Double metal cyanide catalyst, containing zinc hexacyanocobaltate, tert-butanol and polypropylene glycol having a number-average molecular weight of 1000 g/mol, according to example 6 in WO-A 01/80994.

(35) Cyclic propylene carbonate (cPC): from Acros, art. no.: 131560025

(36) Cyclic ethylene carbonate (cEC): from Acros, art. no.: 118410010

(37) Ethanolamine: from Merck; art. no.: 800849

(38) Stabilizer 1: siloxane-based foam stabilizer, Tegostab BE 2370, Evonik Goldschmidt

(39) Isocyanate 1: mixture of 80% by weight of tolylene 2,4- and 20% by weight of tolylene 2,6-diisocyanate, available under the Desmodur T 80 name, Bayer MaterialScience AG

(40) Catalyst 1: bis(2-dimethylaminoethyl) ether in dipropylene glycol, available as Addocat 108, from Rheinchemie

(41) Catalyst 2: tin(II) ethylhexonate, available as Dabco T-9, from Air Products

(42) Preparation of Urethane Alcohols:

Example 1a

(43) A 10 L four-neck flask having a reflux condenser and thermometer was initially charged with cyclic propylene carbonate (6080 g, 59.6 mol). Subsequently, ethanolamine (2405 g, 39.6 mol) was gradually added dropwise at 60 C. within 50 min at such a rate that the temperature did not exceed 72 C. The reaction mixture was subsequently stirred at 60 C. for 24 h. After cooling to 25 C., the urethane alcohol was obtained.

(44) Properties of the resulting urethane alcohol:

(45) OH number: 507 mg KOH/g

(46) NH number: 0.51 mg KOH/g

(47) Viscosity (25 C.): 268 mPas

Example 1b

(48) 1000 g of urethane alcohol, prepared according to example 1a, was freed of volatile constituents by means of thin-film evaporation (0.1 mbar, 120 C.).

(49) This resulted in a urethane alcohol having the following properties:

(50) OH number: 671 mg KOH/g

(51) NH number: 0.20 mg KOH/g

(52) Viscosity (25 C.): 3170 mPas

Example 2

(53) A 2 L four-neck flask with reflux condenser and thermometer was initially charged with a mixture of cyclic propylene carbonate (1181 g, 11.6 mol) and cyclic ethylene carbonate (62 g, 0.7 mol) which had been heated to 50 C. Subsequently, ethanolamine (500 g, 8.2 mol) was gradually added dropwise at 60 C. within 60 mm at such a rate that the temperature did not exceed 70 C. The reaction was subsequently stirred at 60 C. for 15 h. After cooling to 25 C., the urethane alcohol was obtained.

(54) Properties of the resulting urethane alcohol:

(55) OH number: 523 mg KOH/g

(56) NH number: 0.20 mg KOH/g

(57) Viscosity (25 C.): 313 mPas

Example 3 (LAEM 528)

(58) A 2 L four-neck flask with reflux condenser and thermometer was initially charged with a mixture of cyclic propylene carbonate (1110 g, 10.9 mol) and cyclic ethylene carbonate (123 g, 1.4 mol) which had been heated to 50 C. Subsequently, ethanolamine (500 g, 8.2 mol) was gradually added dropwise at 60 C. within 60 min at such a rate that the temperature did not exceed 79 C. The reaction was subsequently stirred at 60 C. for 15 h. After cooling to 25 C., the urethane alcohol was obtained.

(59) Properties of the resulting urethane alcohol:

(60) OH number: 527 mg KOH/g

(61) NH number: 0.30 mg KOH/g

(62) Viscosity (25 C.): 295 mPas

(63) Preparation of Polyether Carbonate Polyols:

Example 4: Copolymerization of PO and CO2 with Continuous Metered Addition of the Urethane Alcohol Starter Compound

(64) Step () (Drying):

(65) 107 mg of unactivated dried DMC catalyst were suspended in 31 g of 4-methyl-2-oxo-1,3-dioxolane (also referred to hereinafter as cyclic propylene carbonate or cPC) and the suspension was then introduced into a 1 L pressure reactor with a gas metering device. The suspension was then heated up to 130 C. and was introduced together with 26-30 L/h of nitrogen over the course of 30 min and, at the same time, reduced pressure of 75-100 mbar was applied.

(66) Step () (Catalyst Activation):

(67) In the reactor, at 130 C., 1200 rpm and at a supply pressure of about 100 mbar, which was established with nitrogen, an amount of 5 g of propylene oxide (PO) was added all at once. The onset of the reaction was manifested by a temperature spike (hotspot) and by a pressure drop to the starting pressure. After the first pressure drop, the reactor was pressurized with p=50 bar of CO.sub.2 then, for activation, a further 10 g of PO were added all at once. After a delay, there was another temperature spike and the total pressure in the reactor showed a pressure decrease.

(68) Step () (Copolymerization of PO and CO.sub.2 with Continuous Metered Addition of the Urethane Alcohol Starter Compound):

(69) On completion of activation, propylene oxide (196 g) at 1.00 g/min and 18 g of the urethane alcohol from example 1b at 0.104 g/min were metered simultaneously into the reactor. At the same time, the reaction temperature was lowered from 130 C. at 1 C./min to 105 C. The progress of the reaction was monitored via the CO.sub.2 consumption, by keeping the pressure in the reactor constant at 50 bar of CO.sub.2 by continuously regulated replenishment. After the addition of PO had ended, stirring was continued at 105 C. and reaction pressure until the CO.sub.2 consumption had abated (1200 rpm). This further reaction took about 3 h.

(70) The product mixture obtained was freed of traces of monomeric propylene oxide by means of a rotary evaporator and stabilized by the addition of 500 ppm of Irganox 1076. Subsequently, the cyclic propylene carbonate was removed from the reaction mixture by means of thin-film evaporation (0.1 mbar, 120 C.). The CO.sub.2 content incorporated in the polycarbonate polyol, the viscosity, OH number and functionality were determined by the abovementioned analytical methods.

(71) Properties of the resulting polyether carbonate polyol:

(72) OH number: 58.7 mg KOH/g

(73) Viscosity (25 C.): 4640 mPas

(74) CO.sub.2 content: 15.0%

(75) Functionality: 2.74

Example 5: Copolymerization of PO and CO2 with Continuous Metered Addition of the Urethane Alcohol Starter Compound

(76) Step () (Drying):

(77) 107 mg of unactivated dried DMC catalyst were suspended in 31 g of cPC and the suspension was then introduced into a 1 L pressure reactor with a gas metering device. The suspension was then heated up to 130 C. and was introduced together with 26-30 L/h of nitrogen over the course of 30 min and, at the same time, reduced pressure of 75-100 mbar was applied.

(78) Step () (Catalyst Activation):

(79) In the reactor, at 130 C., 1200 rpm and at a supply pressure of about 100 mbar, which was established with nitrogen, an amount of 5 g of propylene oxide (PO) was added all at once. The onset of the reaction was manifested by a temperature spike (hotspot) and by a pressure drop to the starting pressure. After the first pressure drop, the reactor was pressurized with p=50 bar of CO.sub.2 then, for activation, a further 10 g of PO were added all at once. After a delay, there was another temperature spike and the total pressure in the reactor showed a pressure decrease.

(80) Step () (Copolymerization of PO and CO.sub.2 with Continuous Metered Addition of the Urethane Alcohol Starter Compound):

(81) On completion of activation, propylene oxide (196 g) at 1.01 g/min and 18 g of the urethane alcohol from example 2 at 0.100 g/min were metered simultaneously into the reactor. At the same time, the reaction temperature was lowered from 130 C. at 1 C./min to 105 C. The progress of the reaction was monitored via the CO.sub.2 consumption, by keeping the pressure in the reactor constant at 50 bar of CO.sub.2 by continuously regulated replenishment. After the addition of PO had ended, stirring was continued at 105 C. and reaction pressure until the CO.sub.2 consumption had abated (1200 rpm). This further reaction took about 3 h.

(82) The product mixture obtained was freed of traces of monomeric propylene oxide by means of a rotary evaporator and stabilized by the addition of 500 ppm of Irganox 1076. Subsequently, the cyclic propylene carbonate was removed from the reaction mixture by means of thin-film evaporation (0.1 mbar, 120 C.). The CO.sub.2 content incorporated in the polyether carbonate polyol, the viscosity and OH number were determined by the abovementioned analytical methods.

(83) Properties of the resulting polyether carbonate polyol:

(84) OH number: 50.7 mg KOH/g

(85) Viscosity (25 C.): 7370 mPas

(86) CO.sub.2 content: 16.6%

Example 6: Copolymerization of PO and CO2 with Continuous Metered Addition of the Urethane Alcohol Starter Compound

(87) Step () (Drying):

(88) 107 mg of unactivated dried DMC catalyst were suspended in 31 g of cPC and the suspension was then introduced into a 1 L pressure reactor with a gas metering device. The suspension was then heated up to 130 C. and was introduced together with 26-30 L/h of nitrogen over the course of 30 min and, at the same time, reduced pressure of 75-100 Mbar was applied.

(89) Step () (Catalyst Activation):

(90) In the reactor, at 130 C. 1200 rpm and at a supply pressure of about 100 mbar, which was established with nitrogen, an amount of 5 g of propylene oxide (PO) was added all at once. The onset of the reaction was manifested by a temperature spike (hotspot) and by a pressure drop to the starting pressure. After the first pressure drop, the reactor was pressurized with p=50 bar of CO.sub.2 then, for activation, a further 10 g of PO were added all at once. After a delay, there was another temperature spike and the total pressure in the reactor showed a pressure decrease.

(91) Step () (Copolymerization of PO and CO.sub.2 with Continuous Metered Addition of the Urethane Alcohol Starter Compound):

(92) On completion of activation, propylene oxide (196 g) at 1.00 g/min and 18 g of the urethane alcohol from example 3 at 0.100 g/min were metered simultaneously into the reactor. At the same time, the reaction temperature was lowered from 130 C. at 1 C./min to 105 C. The progress of the reaction was monitored via the CO.sub.2 consumption, by keeping the pressure in the reactor constant at 50 bar of CO.sub.2 by continuously regulated replenishment. After the addition of PO had ended, stirring was continued at 105 C. and reaction pressure until the CO.sub.2 consumption had abated (1200 rpm). This further reaction took about 3 h.

(93) The product mixture obtained was freed of traces of monomeric propylene oxide by means of a rotary evaporator and stabilized by the addition of 500 ppm of Irganox 1076. Subsequently, the cyclic propylene carbonate was removed from the reaction mixture by means of thin-film evaporation (0.1 mbar, 120 C.). The CO.sub.2 content incorporated in the polyether carbonate polyol, the viscosity, and OH number were determined by the abovementioned analytical methods.

(94) Properties of the resulting polyether carbonate polyol:

(95) OH number: 58.7 mg KOH/g,

(96) Viscosity (25 C.): 4640 mPas

(97) CO.sub.2 content: 15.0%

Example 7: Continuous Process with Continued Metered Addition of the Urethane Alcohol Starter Compound

(98) The reaction was conducted in a continuously operated stirred tank cascade consisting of five pressure vessels connected in series (reactor R1, reactor R2, reactor R3, reactor R4 and reactor R5).

(99) R1, R2, R3, R4 and R5 are each reactors continuously stirred reactors:

(100) Reactor R1 (capacity 300 mL) had a height (internal) of 10.16 cm and an internal diameter of 6.35 cm. The reactor was equipped with an electrical heating jacket (maximum heating power 510 watts). The reactor had countercooling in the form of a U-shaped immersed tube of external diameter 3.17 mm, which projected into the reactor to 5 mm above the base, and through which cooling water flowed at about 10 C. The water flow was switched on and off by means of a magnetic valve. In addition, the reactor was equipped with an inlet tube for inert gas (nitrogen), an inlet tube for propylene oxide, and a temperature sensor of diameter 3.17 mm, which projected into the reactor to 3 mm above the base. In addition, the reactor was equipped with an inlet tube for inert gas or carbon dioxide and a connection for vacuum, which led into the gas phase of the reactor. The reactor was stirred by means of a pitched blade stirrer, which had four stirrer paddles (45) each having a diameter of 35 mm and a height of 10 mm. By means of a mass flow regulator, the liquid phase was metered into reactor R2.

(101) Reactor R2 (capacity 300 mL) had a height (internal) of 10.16 cm and an internal diameter of 6.35 cm. The reactor was equipped with an electrical heating jacket (maximum heating power 510 watts). The reactor had countercooling in the form of a spiral-wound tube of external diameter 3.17 mm, through which cooling water flowed at about 10 C. The water flow was switched on and off by means of a magnetic valve. In addition, the reactor was equipped with an inlet tube for inert gas (nitrogen), an inlet tube for propylene oxide, and a temperature sensor of diameter 3.17 min, which projected into the reactor. In addition, the reactor was equipped with an inlet tube for inert gas or carbon dioxide and a connection for vacuum, which led into the gas phase of the reactor. The reactor was stirred by means of a pitched blade stirrer, which was in the middle of a flow direction plate having baffles. The pitched blade stirrer was a stirrer having four stirrer paddles (45) having a diameter of 35 mm and a height of 10 mm. In addition, the reactor had a sightglass. Via a heated tube, the overflow was conducted into reactor R3.

(102) Reactor R3 (capacity 300 mL) had a height (internal) of 10.16 cm and an internal diameter of 6.35 cm. The reactor was equipped with an electrical heating jacket (maximum heating power 510 watts). The reactor had countercooling in the form of a spiral-wound tube of external diameter 3.17 mm, through which cooling water flowed at about 10 C. The water flow was switched on and off by means of a magnetic valve. In addition, the reactor was equipped with an inlet tube for the reaction mixture from reactor R2 and a temperature sensor of diameter 3.17 mm. Via a heated tube, the overflow was conducted into reactor R4. Reactor R4 was of identical design to reactor R3. The overflow was conducted via a heated tube into reactor R5.

(103) Reactor R5 (capacity 1700 mL) had a height (internal) of 28.5 cm and an internal diameter of 9.82 cm. The reactor was equipped with an electrical heating jacket (maximum heating power 510 watts). The reactor had countercooling in the form of an immersed tube bent in the form of a wave and having external diameter 6.35 min, which projected into the reactor to 5 mm above the base and through which cooling water flowed at about 10 C. The water flow was switched on and off by means of a magnetic valve. In addition, the reactor was equipped with a temperature sensor of diameter 3.17 mm, which projected into the reactor to 3 mm above the base. The reactor was stirred by means of a spiral stirrer where a rectangular metal rod in spiral form having a cross section of 12.445 mm was mounted on the stirrer shaft, with an external spiral diameter of 6 cm, an internal diameter of 4.6 cm and a height of 14 cm. The gas phase was discharged into the waste air via a pressure-retaining valve,

(104) For the recording of the propylene oxide concentration during the catalyst activation in reactor R2, a Bruker MATRIX-MF spectrometer equipped with 3.17 mm ATR-IR fiber optic probes was used. The ATR-IR fiber optic probes (90 diamond prism with base area 12 mm and height 1 mm as ATR element, 245 reflection of the IR beam. IR beam introduced via optical fibers) was installed into the reactors in such a way that the diamond at the end of the 3.17 mm ATR fiber optic probe was completely immersed into the reaction mixture. IR spectra (mean of 100 scans) were recorded every 60 seconds in the range of 4000-650 cm.sup.1 with a resolution of 4 cm.sup.1. The propylene oxide concentration was monitored via recording of the characteristic bands for propylene oxide at 830 cm.sup.1. A decrease in the intensity of the bands at 830 cm.sup.1 to 5% of the maximum value was regarded as complete conversion of propylene oxide.

(105) For the removal of the volatile constituents, the reaction mixture was guided through a falling-film evaporator. The solution (0.1 kg in 1 h) ran along the inner wall of a tube of diameter 70 mm and length 200 mm which was heated externally to 120 C., in the course of which the reaction mixture was distributed homogeneously as a thin film on the inner wall of each falling-film evaporator by three rollers of diameter 10 mm rotating at a speed of 250 rpm. Within the tube, a pressure of <1 mbar was established by means of a pump. The reaction mixture which had been purified to free it of volatile constituents (e.g. unconverted propylene oxide, cyclic propylene carbonate) was collected in a receiver at the lower end of the heated tube.

(106) Process Steps:

(107) Preparation of a Mixture of DMC Catalyst and Urethane Alcohol Starter Compound:

(108) A 300 mL pressure reactor (reactor R1) equipped with a pitched blade stirrer was initially charged with a mixture of DMC catalyst (0.645 g) and urethane alcohol from Example 1a (250.00 g). The reactor was closed and the mixture of DMC catalyst and starter was stirred in reactor R1 at 40 C. at 300 rpm and 1 bar overnight. The pressure in reactor R1 was regulated stepwise to 47 bar with nitrogen which was introduced into the gas phase.

(109) Step () (Activation):

(110) A 300 mL pressure reactor (reactor R2) equipped with pitched blade stirrer, baffles and flow direction plate was initially charged with a mixture of DMC catalyst (0.059 g) and propylene carbonate (150.10 g) and stirred at 650 rpm. Subsequently, at the base of the reactor, a gentle nitrogen flow of 10 g/h into the reaction mixture was established with the waste air tap open. The reaction mixture was inertized for 31 min and the reactor was then closed. The reactor was heated up to 130 C. 15 g of propylene oxide were metered in with the aid of a mass flow regulator (200 g/h). The decrease in the concentration of propylene oxide was monitored via IR spectroscopy. The reaction mixture was stirred (650 rpm) until the conversion of the propylene oxide was complete (about 15 min). Subsequently, twice more, 15 g of propylene oxide were metered in with the aid of a mass flow regulator (200 g/h) and the reaction mixture was stirred (650 rpm) each time until the conversion of the propylene oxide was complete (about 15 min). The occurrence of a brief increase in evolution of heat in the reactor after addition of the propylene oxide confirmed that the catalyst had been activated. Subsequently, by means of a mass flow meter and a micro-annular gear pump, the mixture of urethane alcohol and DMC catalyst was metered in from reactor R1 (20 g/h). The flow was regulated to 7.70 g/h as soon as the exit of the mixture of urethane alcohol and DMC catalyst was visible through the sightglass at the end of the immersed conduit (about 8 min). In addition, 71 g/h of propylene oxide were metered continuously into reactor R2 via a mass flow regulator and an immersed conduit.

(111) Step () (Copolymerization):

(112) As soon as the overflow from reactor R2 (at liquid volume 195 mL) had been reached, the valve at the outlet of reactor R2 was opened. CO.sub.2 was introduced continuously into the gas phase of reactor R2 at a flow rate of 23 g/h. The outlet stream was led through the further pressure vessels (reactors R3, R4 and R5) and a pressure-retaining valve which had been set to supply pressure 50 bar. The temperature in reactors R3 and R4 was regulated to 130 C., and that in reactor R5 to 100 C. The stirrer speed in reactors R3 and R4 was 650 rpm, and that in reactor R5 200 rpm. The product mixture was collected at 100 C. under pressure in reactor R5 and stirred at 200 rpm. The temperature of the heated conduits between reactors R1 and R2 was 50 C., and that of those between reactors R2-R3 and R3-R4 and R4-R5 was 100 C. After an operating time of 94 hours, a sample of the liquid phase was taken from reactor R5 via a valve. After the volatile constituents had been removed from the reaction mixture by means of the falling-film evaporator (see above), the polyether carbonate polyol was obtained:

(113) Properties of the Resulting Polyether Carbonate Polyol:

(114) OH number: 66.3 mg KOH/g

(115) Viscosity (25 C.): 1855 mPas

(116) CO.sub.2 content: 10.2%

Examples 8-11: Production of Flexible Polyurethane Foams

(117) Flexible polyurethane foams were produced according to the recipes specified in table 1 below. The proportions of the components are listed in parts by weight.

(118) High-quality flexible polyurethane foams having homogeneous cell structure were obtained, which were characterized by determining the apparent densities and compression hardnesses (compression hardness measured at 40% compression) (table 1).

(119) TABLE-US-00001 TABLE 1 Preparation of flexible polyurethane foams Example 8 9 10 11 Polyether carbonate polyol from 100 100 example 4 [parts by wt.] Polyether carbonate polyol from 100 example 5 [parts by wt.] Polyether carbonate polyol from 100 example 6 [parts by wt.] Stabilizer 1 [parts by wt.] 2.4 1.2 2.4 2.4 Catalyst 1 [parts by wt.] 0.15 0.12 0.15 0.15 Catalyst 2 [parts by wt.] 0.14 0.18 0.14 0.14 Water [parts by wt.] 2.50 4.50 2.50 2.50 Isocyanate 1 [parts by wt.] 36.0 56.8 34.5 34.2 NCO index 108 108 108 108 Apparent density [kg/m.sup.3] 39.3 27.8 41.4 37.2 Compression hardness, 4th cycle 3.0 4.4 3.4 0 [kPa]