METHOD FOR PRODUCING POLYETHER THIOCARBONATE POLYOLS

Abstract

A process for preparing polyether thiocarbonate polyols comprising the step of reacting carbon disulfide and at least one alkylene oxide in the presence of a double metal cyanide catalyst and at least one H-functional starter compound, wherein before first contact with carbon disulfide the double metal cyanide catalyst has previously been contacted with at least one alkylene oxide the the invention likewise relates to a polyol obtainable by the process according to the invention.

Claims

1. A process for preparing polyether thiocarbonate polyols comprising reacting carbon disulfide and at least one alkylene oxide in the presence of a double metal cyanide catalyst and at least one H-functional starter compound, wherein the double metal cyanide catalyst has previously been contacted with at least one alkylene oxide before contacting with carbon disulfide.

2. The process according to claim 1, wherein the at least one alkylene oxide comprises at least one of ethylene oxide, propylene oxide and styrene oxide.

3. The process according to claim 1, wherein the at least one H-functional starter compound comprises at least one of a polyether polyol, a polyester polyol, a polyether ester polyol, a polyether carbonate polyol, a polycarbonate polyol, and a polyacrylate polyol.

4. The process according to claim 1, wherein the molar ratio of the at least one employed alkylene oxide to the employed carbon disulfide is in a range from ≥1:1 to ≤100:1.

5. The process according to claim 1 to 4, comprising (α) initially charging a reactor with the double metal cyanide catalyst and the at least one H-functional starter compounds, passing an inert gas through the reactor at a temperature of 50° C. to 200° C., and simultaneously establishing a reduced (absolute) pressure in the reactor of 10 mbara to 800 mbara by removing the inert gas; (β) admixing the mixture from (α) with a portion (based on the entirety of the amount of alkylene oxides employed in steps (β) and (γ)) of the at least one alkylene oxide at temperatures of 50° C. to 200° C.; (γ) adding carbon disulfide and at least one alkylene oxide to the mixture resulting from (β).

6. The process according to claim 5, wherein carbon disulfide and the at least one alkylene oxide in (γ) are continuously metered into the mixture resulting from (β).

7. The process according to claim 5, wherein (γ) is performed at 50° C. to 150° C.

8. The process according to claim 1, comprising (α′) initially charging a reactor with the double metal cyanide catalyst and the at least H-functional starter compound and/or a suspension medium which does not comprise H-functional groups, passing an inert gas through the reactor at a temperature of 50° C. to 200° C., and simultaneously establishing a reduced (absolute) pressure of 10 mbara to 800 mbara in the reactor by removing the inert gas; (β′) admixing the mixture from (α′) with a portion (based on the entirety of the amount of alkylene oxides employed in steps (β′) and (γ′)) of the at least one alkylene oxide at temperatures of 50° C. to 200° C., and subsequently interrupting the addition of the at least one alkylene oxide; (γ′) continuously metering at least one alkylene oxide, carbon disulfide, and at least one H-functional starter compound, and optionally double metal cyanide catalyst into the reactor during the reaction.

9. The process according to claim 8, comprising (α′) initially charging a reactor with the double metal cyanide catalyst in a suspension medium which does not comprise H-functional groups, passing an inert gas through the reactor at a temperature of 50° C. to 200° C., and simultaneously establishing a reduced (absolute) pressure in the reactor of 10 mbara to 800 mbara by removing the inert gas.

10. The process according to claim 8, wherein in step (γ′) the metered addition of the at least one H-functional starter compound is terminated before the addition of the at least one alkylene oxide.

11. The process according to claim 8, wherein step (γ′) is performed at 50° C. to 150° C.

12. A polyether thiocarbonate polyol obtainable by a process according to claim 1, wherein the total content of the functional group:
—S—C(═O)— in the polymer is ≤21 mol %.

13. The polyether thiocarbonate polyol according to claim 12 having a refractive index n.sub.D (20° C.) of ≥1.45.

14. A polyurethane polymer obtainable from the reaction of a polyol component comprising the polyether thiocarbonate polyol according to claim 12 with at least one polyisocyanate component.

15. The polyurethane polymer according to claim 14, wherein the polyurethane polymer is a polyurethane foam.

Description

EXAMPLES

[0129] The invention is more particularly described with reference to the examples which follow but without any intention to limit the invention thereto.

[0130] H-functional starter compounds (starters) used:

PET-1 difunctional poly(oxypropylene)polyol having an OH number of 112 mg.sub.KOH/g
PET-2 trifunctional poly(oxypropylene)polyol having an OH number of 240 mg.sub.KOH/g

[0131] The DMC catalyst was prepared according to example 6 of WO-A 01/80994.

[0132] The 300 ml pressure reactor used in the examples had an (internal) height of 10.16 cm and an internal diameter of 6.35 cm. The reactor was equipped with an electrical heating jacket (510 watt maximum heating power). The counter-cooling consisted of an immersed tube of external diameter 6 mm which had been bent into a U shape and which projected into the reactor up 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 and a thermal sensor of diameter 1.6 mm, which both projected into the reactor up to 3 mm above the base.

[0133] The heating power of the electrical heating jacket during activation [step (β)] was on average about 20% of the maximum heating power. As a result of the adjustment, the heating power varied by ±5% of the maximum heating power. The occurrence of increased evolution of heat in the reactor, brought about by the rapid reaction of propylene oxide during the activation of the catalyst [step (β)], was observed via reduced heating power of the heating jacket, engagement of the counter-cooling, and, as the case may be, a temperature increase in the reactor. The occurrence of evolution of heat in the reactor, brought about by the continuous reaction of propylene oxide during the reaction [step (γ)], led to a fall in the power of the heating jacket to about 8% of the maximum heating power. As a result of the adjustment, the heating power varied by ±5% of the maximum heating power.

[0134] The hollow-shaft stirrer used in the examples was a hollow-shaft stirrer where the gas was introduced into the reaction mixture via a hollow shaft in the stirrer. The stirrer body mounted on the hollow shaft comprised four arms having a diameter of 35 mm and a height of 14 mm. The arm was equipped at each end with two gas outlets of 3 mm in diameter. The turning stirrer created a negative pressure such that the gas above the reaction mixture was sucked away and was introduced into the reaction mixture via the hollow shaft of the stirrer.

[0135] The copolymerization of propylene oxide and CS.sub.2 resulted not only in the cyclic propylene thiocarbonate but also in the polyether thiocarbonate polyol containing polythiocarbonate units (—S(C═S)—) shown in formula (X)

##STR00002##

and also polythiocarbonate units (—S(C═O)—) shown in formula (XI):

##STR00003##

[0136] The copolymerization of propylene oxide and CS.sub.2 resulted not only in the cyclic propylene thiocarbonate but also in the polyether thiocarbonate polyol additionally containing polyether units shown in formula (XII)

##STR00004##

[0137] Characterization of the reaction mixture was by .sup.1H NMR spectroscopy, IR spectroscopy and gel permeation chromatography.

[0138] The ratio of the amount of cyclic propylene thiocarbonate to polyether thiocarbonate polyol (selectivity) and the molar ratio of thiocarbonate groups to ether groups in the polyether thiocarbonate polyol (e/f ratio) and the proportion of converted propylene oxide (C in mol %) were determined by .sup.1H NMR spectroscopy. Each sample was dissolved in deuterated chloroform and analyzed on a Bruker spectrometer (AV400, 400 MHz). The relevant resonances in the .sup.1H NMR spectrum (based on TMS=0 ppm) which were used for integration are as follows: [0139] I1: 1.11-1.16: CH.sub.3 group of the polyether units, of the polythiocarbonate units and of the polythiocarbonate units (—S(C═O)—), area of resonance corresponds to three H atoms [0140] I2: 1.53-1.55: CH.sub.3 group of the cyclic monothiocarbonate, area of resonance corresponds to three H atoms [0141] I3: 1.64-1.66: CH.sub.3 group of the cyclic thiocarbonate, area of resonance corresponds to three H atoms [0142] I4: 4.47-4.58: CH.sub.2 group of the polythiocarbonate units, area of resonance corresponds to two H atoms [0143] I5: 5.10-5.12: CH group of the polythiocarbonate units (—S(C═O)—), area of resonance corresponds to one H atom [0144] I6: 5.77-5.81: CH group of the polythiocarbonate units, area of resonance corresponds to one H atom

[0145] Reported are the molar ratio of the amount of linear polyether thiocarbonate polyol (P mol %) to cyclic thiocarbonate based on the sum of the amount of propylene oxide employed during activation and copolymerization and the molar ratio of thiocarbonate groups (—S(C═S)—) to thiocarbonate groups (—S(C═O)—) in the polyether thiocarbonate polyol.

[0146] Taking account of the relative intensities, the values were calculated as follows:

Polyether thiocarbonate polyol (P mol %)=[((I1/3)/((I1/3)+(I2/3+(I3/3))]*100%

Molar ratio of thiocarbonate groups (—S(C═S)—) to thiocarbonate groups (—S(C═O)—) in the polyether thiocarbonate polyol:

e/e′=(I4/2)+(I6))/I5

[0147] Proportion of thiocarbonate groups (—S(C═S)—) resulting from incorporation of carbon disulfide in the repeating units of the polyether thiocarbonate polyol:

thiocarbonate groups (—S(C═S)—) mol %=[((I4/2)+(I6))/((I4/2)+I5+I6)]*100%

[0148] Proportion of thiocarbonate groups (—S(C═O)—) resulting from incorporation of carbon disulfide in the repeating units of the polyether thiocarbonate polyol:

thiocarbonate groups (—S(C═O)—) mol %=[(I5/((I4/2)+I5+I6)]*100%

[0149] The number-average M.sub.n and the weight-average M.sub.w of the molecular weight of the resulting polymers was determined by gel permeation chromatography (GPC). The procedure of DIN 55672-1 was followed: “Gel permeation chromatography, Part 1—Tetrahydrofuran as eluent” (SECurity GPC System from PSS Polymer Service, flow rate 1.0 mL/min; columns: 2×PSS SDV linear M, 8×300 mm, 5 μm; RID detector). Polystyrene samples of known molar mass were used for calibration.

[0150] The OH number (hydroxyl number) was determined based on DIN 53240-2 but using N-methylpyrrolidone rather than THF/dichloromethane as solvent. A 0.5 molar ethanolic KOH solution was used for titration (endpoint recognition by potentiometry). The test substance used was castor oil with certified OH number. The reporting of the unit in “mg/g” relates to mg[KOH]/g[polyether thiocarbonate polyol].

[0151] Viscosity was determined on an Anton Paar Physica MCR 501 rheometer. A cone-plate configuration having a separation of 1 mm was selected (DCP25 measurement system). The polythioether carbonate polyol (0.1 g) was applied to the rheometer plate and subjected to a shear of 0.01 to 1000 l/s at 25° C. and the viscosity was measured every 10 s for 10 min. The viscosity averaged over all measurement points is reported.

[0152] For rheological determination of the gel point for the polyurethane polymer the polythioether carbonate polyols were admixed with an equimolar amount of Desmodur N3300 (hexamethylene diisocyanate trimer) and 2000 ppm of dibutyltin laurate (2% in diphenyl ether). The complex moduli G′ (storage modulus) and G″ (loss modulus) were determined in an oscillation measurement at 40° C. and a frequency of 1 Hz, using a plate/plate configuration with a plate diameter of 15 mm, a plate-to-plate distance of 1 mm, and a 10 percent deformation. The gel point was defined as time at which G′=G″.

[0153] The proportion of sulfur atoms (S wt %) in the polyether thiocarbonate polyol was determined using elemental analysis. Analysis in the Leco “CHN628” instrument is based on combustion at 950° C. (afterburning space 850° C.) in a pure oxygen stream and subsequent analysis in a stream of helium as carrier gas. Analysis is effected based on the standards DIN 51732 and DIN EN ISO 16948. The sulfur content is determined based on DIN CENTS 15289 after combustion of the sample in the oxygen stream and drying of the combustion gas by means of infrared cells.

[0154] The refractive index of polyether thiocarbonate polyols was determined using an AR4 Abbe refractometer from A.KRÜSS Optronic GmbH.

[0155] IR spectroscopy: FT-IR Spectra were recorded using a Bruker Alpha-P FT-IR Spectrometer (Bruker Optics), equipped with a diamond head. All samples were recorded in a range of 4000-400 cm.sup.−1 with 24 scans at a resolution of 4 cm.sup.−1. The spectra were evaluated using OPUS 7.0 software (Bruker Optics).

[0156] The following examples 1 to 4 were performed with PET-1 as the starter. The values for pressure refer to the absolute pressure.

Example 1: Polymerisation of Propylene Oxide and CS.SUB.2 .with a DMC Catalyst Dried Under Argon and Activated in an Ar Atmosphere in a Semi-Batch Process with Addition of CS2 in Step γ

[First Activation Stage, Step (α)]

[0157] A 300 ml pressure reactor fitted with a hollow-shaft stirrer was initially charged with a mixture of DMC catalyst (18 mg) and PET-1 (20 g). The reactor was sealed and the pressure in the reactor reduced to 5 mbara for five minutes. The pressure in the reactor was then adjusted to 50 mbara by application of a light Ar stream and simultaneous removal of the gas with a pump. The reactor was heated to 130° C. and the mixture was stirred (800 rpm) at 130° C. under reduced pressure (50 mbara) and a light Ar stream for 30 minutes.

[Second Activation Stage, Step (β)]

[0158] A pressure of 2 bara of Ar was established. 2 g of propylene oxide were metered in using an HPLC pump (1.0 mL/min) and the reaction mixture was stirred (800 rpm) for 20 min. Subsequently, two further portions of propylene oxide of 2 g each were metered in by means of the HPLC pump (1.0 mL/min) and the reaction mixture was stirred (800 rpm) for 20 min in each case. The occurrence of a brief increase in evolution of heat in the reactor during this time confirmed the activation of the catalyst.

[Polymerisation Stage, Step (γ)]

[0159] After cooling to 110° C., a further 34 g of propylene oxide were metered in by means of an HPLC pump (1.0 ml/min) with continued stirring. 4 min after commencement of the addition of propylene oxide, 15 g of CS.sub.2 were simultaneously metered in by means of an HPLC pump (0.5 mL/min). The reaction mixture was subsequently stirred at 110° C. for a further 1 h. The reaction was stopped by cooling the reactor with ice water, the positive pressure was released and the resulting product analyzed.

[0160] The NMR spectroscopic analysis of the reaction mixture showed full conversion of the propylene oxide.

[0161] The selectivity for linear polyether thiocarbonate polyol over cyclic thiocarbonate was ≥99%.

[0162] The molar ratio of thiocarbonate groups (—S(C═S)—) to thiocarbonate groups (—S(C═O)—) in the polyether thiocarbonate polyol was 3.9.

[0163] The proportion of sulfur atoms (wt %) in the polyether thiocarbonate polyol was 6.2 wt %.

[0164] The obtained polyether thiocarbonate polyol had a molecular weight M.sub.n=3411 g/mol, M.sub.w=5798 g/mol and a polydispersity of 1.7.

[0165] The OH number of the resulting mixture was 44.0 mg.sub.KOH/g.

[0166] The refractive index of the obtained polyether thiocarbonate polyol was 1.51.

[0167] The time until attainment of the gel point for the polyurethane polymer was 8.2 min.

Example 2: Polymerisation of Propylene Oxide and CS2 with a DMC Catalyst Dried Under Argon and Activated in an Ar Atmosphere in a Semi-Batch Process

[First Activation Stage, Step (α)]

[0168] A 300 ml pressure reactor fitted with a hollow-shaft stirrer was initially charged with a mixture of DMC catalyst (18 mg) and PET-1 (20 g). The reactor was sealed and the pressure in the reactor reduced to 5 mbara for five minutes. The pressure in the reactor was then adjusted to 50 mbara by application of a light Ar stream and simultaneous removal of the gas with a pump. The reactor was heated to 130° C. and the mixture was stirred (800 rpm) at 130° C. under reduced pressure (50 mbara) and a light Ar stream for 30 minutes.

[Second Activation Stage, Step (β)]

[0169] A pressure of 2 bara of Ar was established. 2 g of propylene oxide were metered in using an HPLC pump (1.0 mL/min) and the reaction mixture was stirred (800 rpm) for 20 min. Subsequently, two further portions of propylene oxide of 2 g each were metered in by means of the HPLC pump (1.0 mL/min) and the reaction mixture was stirred (800 rpm) for 20 min in each case. The occurrence of a brief increase in evolution of heat in the reactor during this time confirmed the activation of the catalyst.

[Polymerisation Stage, Step (γ)]

[0170] After cooling to 110° C., 15 g of CS.sub.2 were metered in by means of an HPLC pump (2.0 ml/min) with continued stirring. After the addition of CS.sub.2, 34 g of propylene oxide were metered in by means of an HPLC pump (1 mL/min). The reaction mixture was subsequently stirred at 110° C. for a further 1 h. The reaction was stopped by cooling the reactor with ice water, the positive pressure was released and the resulting product analyzed.

[0171] The NMR spectroscopic analysis of the reaction mixture showed full conversion of the propylene oxide.

[0172] The selectivity for linear polyether thiocarbonate polyol over cyclic thiocarbonate was ≥99%.

[0173] The molar ratio of thiocarbonate groups (—S(C═S)—) to thiocarbonate groups (—S(C═O)—) in the polyether thiocarbonate polyol was 8.9.

[0174] The proportion of sulfur atoms (wt %) in the polyether thiocarbonate polyol was 3.7 wt %.

[0175] The obtained polyether thiocarbonate polyol had a molecular weight M.sub.n=3116 g/mol, M.sub.w=6232 g/mol and a polydispersity of 2.0.

[0176] The OH number of the resulting mixture was 42.6 mg.sub.KOH/g.

[0177] The refractive index of the obtained polyether thiocarbonate polyol was 1.46.

[0178] The time until attainment of the gel point for the polyurethane polymer was 6.3 min.

Example 3 (Comparative): Preparation of a Polyether Thiocarbonate Polyol Via a Semi-Batch Process with Addition of CS2 in Step α

[First Activation Stage, Step (α)]

[0179] A 300 ml pressure reactor fitted with a sparging stirrer was initially charged with a mixture of DMC catalyst (18 mg), PET-1 (20 g) and CS.sub.2 (15 g). The reactor was sealed and the pressure in the reactor reduced to 5 mbara for five minutes. The pressure in the reactor was then adjusted to 50 mbara by application of a light Ar stream and simultaneous removal of the gas with a pump. The reactor was heated to 130° C. and the mixture was stirred (800 rpm) at 130° C. under reduced pressure (50 mbara) and a light Ar stream for 30 minutes.

[Second Activation Stage, Step (β)]

[0180] A pressure of 2 bara of Ar was established. 2 g of propylene oxide were metered in using an HPLC pump (1.0 mL/min) and the reaction mixture was stirred (800 rpm) for 20 min. Subsequently, two further portions of propylene oxide of 2 g each were metered in by means of the HPLC pump (1.0 mL/min) and the reaction mixture was stirred (800 rpm) for 20 min in each case. The occurrence of a brief increase in evolution of heat in the reactor during this time confirmed the activation of the catalyst.

[Polymerisation Stage, Step (γ)]

[0181] After cooling to 110° C., 34 g of propylene oxide were metered in by means of an HPLC pump (1.0 ml/min) with continued stirring. The reaction mixture was subsequently stirred at 110° C. for a further 1 h. The reaction was stopped by cooling the reactor with ice water, the positive pressure was released. No product was obtained.

Example 4 (Comparative): Preparation of a Polyether Thiocarbonate Polyol Via a Semi-Batch Process with Addition of CS2 in Step β

[First Activation Stage, Step (α)]

[0182] A 300 ml pressure reactor fitted with a hollow-shaft stirrer was initially charged with a mixture of DMC catalyst (18 mg) and PET-1 (20 g). The reactor was sealed and the pressure in the reactor reduced to 5 mbara for five minutes. The pressure in the reactor was then adjusted to 50 mbara by application of a light Ar stream and simultaneous removal of the gas with a pump. The reactor was heated to 130° C. and the mixture was stirred (800 rpm) at 130° C. under reduced pressure (50 mbara) and a light Ar stream for 30 minutes.

[Second Activation Stage, Step (β)]

[0183] A pressure of 2 bara of Ar was established. 15 g of CS.sub.2 were metered in via an HPLC pump (2.0 mL/min) with continued stirring and a slight temperature drop was apparent. Once a temperature of 130° C. had been reestablished, 2 g of propylene oxide were metered in using an HPLC pump (1.0 mL/min) and the reaction mixture was stirred (800 rpm) for 20 min. Subsequently, two further portions of propylene oxide of 2 g each were metered in by means of the HPLC pump (1.0 mL/min) and the reaction mixture was stirred (800 rpm) for 20 min in each case. The occurrence of a brief increase in evolution of heat in the reactor during this time confirmed the activation of the catalyst.

[Polymerisation Stage, Step (γ)]

[0184] After cooling to 110° C., 34 g of propylene oxide were metered in by means of an HPLC pump (1.0 ml/min) with continued stirring. The reaction mixture was subsequently stirred at 110° C. for a further 1 h. The reaction was stopped by cooling the reactor with ice water, the positive pressure was released. No product was obtained.

TABLE-US-00001 TABLE 1 Overview of results for preparation of polyether thiocarbonate polyols with variation of the time of addition of carbon disulfide in a semi-batch process Time of Proportion of addition n(PO)/ Selectivity sulfur Refractive Ex- of CS.sub.2 n(CS2) for PETC.sup.b) S(—S(C═S)—) S(—S(C═O)—) atoms index ample.sup.a) [−] [mol/mol] [mol %] [mol %] [mol %] [wt %] [−] 1 [step γ] 3.5 ≥99% 79.9 20.1 6.2 1.51 2 [step γ] 3.5 ≥99% 89.9 10.1 3.7 1.46 3 [step α] 3.5 No product was obtained. (comp.) 4 [step β] 3.5 No product was obtained. (comp.) .sup.a)comp.: comparative example, PETC: .sup.b)linear polyether thiocarbonate polyol,

[0185] Examples 1 and 2 and comparative examples 3 and 4 show that in the case of addition of carbon disulfide in the polymerization stage (step γ) (example 1-2) the carbon disulfide is incorporated into the polymer while by contrast in the case of addition of carbon disulfide only during the first activation stage (step α) (comparative example 3) or the second activation stage (step β) (comparative example 4) no product is obtained. Likewise, the refractive index of the polymer increases with an increased proportion of incorporated carbon disulfide in the polyether thiocarbonate polyol (examples 1-2). The linear polyether thiocarbonate polyol is likewise obtained in high selectivity over cyclic thiocarbonate and the obtained polyol has a higher ratio of thiocarbonate groups (—S(C═S)—) to thiocarbonate groups (—S(C═O)—) (examples 1-2).

Example 5: Variation of the Starter Polyol Through Use of PET-2 Instead of PET-1 (n(PO)/n(CS2)=3.7)

[0186] Employed in a procedure analogous to example 1 were: PET-2 starter (20 g); DMC catalyst (18 mg); propylene oxide (2+2+2 g in step (B)+36 g in step (γ), 42 g altogether); CS2 (0.5 mL/min=15 g); catalyst activation as described; argon stripping (50 mbara); activation temperature=130° C.; reaction temperature=110° C.; postreaction time=1 h. The reaction was stopped by cooling the reactor with ice water, the positive pressure was released and the resulting product analyzed.

[0187] The NMR spectroscopic analysis of the reaction mixture showed full conversion of the propylene oxide.

[0188] The selectivity of linear polyether thiocarbonate polyol to cyclic thiocarbonate was ≥99%.

[0189] The molar ratio of thiocarbonate groups (—S(C═S)—) to thiocarbonate groups (—S(C═O)—) in the polyether thiocarbonate polyol was 7.3%.

[0190] The proportion of sulfur atoms (wt %) in the polyether thiocarbonate polyol was 6.4 wt %.

[0191] The obtained polyether thiocarbonate polyol had a molecular weight M.sub.n=3430 g/mol, M.sub.w=6517 g/mol and a polydispersity of 1.9.

[0192] The OH number of the resulting mixture was 54.7 mg.sub.KOH/g.

[0193] The refractive index of the obtained polyether thiocarbonate polyol was 1.54.

[0194] The time until the attainment of the gel point for the polyurethane polymer was 2.0 min.

Example 6: Copolymerization of Styrene Oxide and CS.SUB.2 .(n(SO)/n(CS2)=1.8)

[0195] Employed in a procedure analogous to example 1 were: PET-1 starter (20 g); DMC catalyst (18 mg, 300 ppm); styrene oxide (2+2+2 g in step (13)+36 g in step (γ), 42 g altogether); CS.sub.2 (0.5 mL/min=15 g); catalyst activation as described; argon stripping (50 mbara); activation temperature=130° C.; reaction temperature=110° C.; postreaction time=1 h. A polyether thiocarbonate polyol having a viscosity of. 9.22 Pa.Math.s was obtained.

Example 7: Polymerisation of Propylene Oxide and CS2 with a DMC Catalyst Dried Under Argon and Activated in an Ar Atmosphere in a Semi-Batch CAOS Process

[First Activation Stage, Step (α)]

[0196] A 970 mL pressure reactor fitted with a sparging stirrer was initially charged with a mixture of DMC catalyst (30.0 mg) and toluene (175 mL) and the reaction mixture was stirred (800 rpm) for 30 min at 130° C.

[Second Activation Stage, Step (β)]

[0197] A pressure of 2 bar of Ar was established. 2.5 g of propylene oxide were metered in using an HPLC pump (3.0 mL/min) and the reaction mixture was stirred (800 rpm) for 20 min. Subsequently, two further portions of propylene oxide of 2.5 g each were metered in by means of the HPLC pump (3.0 mL/min) and the reaction mixture was stirred (800 rpm) for 20 min in each case. The occurrence of a brief increase in evolution of heat in the reactor during this time confirmed the activation of the catalyst.

[Polymerisation Stage, Step (γ)]

[0198] The temperature was readjusted to 110° C. and a further 77.4 g of propylene oxide were metered in by means of an HPLC pump (1.25 mL/min) with stirring, with continued stirring of the reaction mixture (800 rpm). Three minutes after commencement of the addition of propylene oxide (3.0), 4.5 g of dipropylene glycol were metered in by means of a separate HPLC pump (0.18 mL/min) with stirring. 15 min after commencement of the addition of propylene oxide (15.0 g), 10.0 g of CS.sub.2 were simultaneously metered in by means of a separate HPLC pump (0.13 mL/min). After the addition of propylene oxide had ended, the reaction mixture was stirred at 110° C. for a further 30 min. The reaction was stopped by cooling the reactor with ice water, the positive pressure was released and the resulting product analyzed.

[0199] The NMR spectroscopic analysis of the reaction mixture showed full conversion of the propylene oxide.

[0200] The selectivity for linear polyether thiocarbonate polyol over cyclic thiocarbonate was ≥99%.

[0201] The molar ratio of thiocarbonate groups (—S(C═S)—) to thiocarbonate groups (—S(C═O)—) in the polyether thiocarbonate polyol was 13.5.

[0202] The proportion of sulfur atoms (wt %) in the polyether thiocarbonate polyol was 2.1 wt %.

[0203] The obtained polyether thiocarbonate polyol had a molecular weight M.sub.n=2918 g/mol, M.sub.w=5798 g/mol and a polydispersity of 1.81.

[0204] The OH number of the resulting mixture was 40.3 mg.sub.KOH/g.

Example 8 (Comparative): Polymerisation of Propylene Oxide and CS2 with a DMC Catalyst Dried Under Argon and Activated in an Ar Atmosphere in a Semi-Batch CAOS Process with Addition of CS.SUB.2 .in Step α

[First Activation Stage, Step (α)]

[0205] A 970 mL pressure reactor fitted with a sparging stirrer was initially charged with a mixture of DMC catalyst (30.0 mg), toluene (175 mL) and CS.sub.2 (10.0 g) and the reaction mixture was stirred (800 rpm) for 30 min at 130° C.

[Second Activation Stage, Step (β)]

[0206] A pressure of 2 bar of Ar was established. 2.5 g of propylene oxide were metered in using an HPLC pump (3.0 mL/min) and the reaction mixture was stirred (800 rpm) for 20 min. Subsequently, two further portions of propylene oxide of 2.5 g each were metered in by means of the HPLC pump (3.0 mL/min) and the reaction mixture was stirred (800 rpm) for 20 min in each case. The occurrence of a brief increase in evolution of heat in the reactor during this time confirmed the activation of the catalyst.

[Polymerisation Stage, Step (γ)]

[0207] The temperature was readjusted to 110° C. and a further 77.4 g of propylene oxide were metered in by means of an HPLC pump (1.25 mL/min) with stirring, with continued stirring of the reaction mixture (800 rpm). Three minutes after commencement of the addition of propylene oxide (3.0), 4.5 g of dipropylene glycol were metered in by means of a separate HPLC pump (0.18 mL/min) with stirring. After the addition of propylene oxide had ended, the reaction mixture was stirred at 110° C. for a further 30 min. The reaction was stopped by cooling the reactor with ice water, the positive pressure was released. No product was obtained.

Example 9 (Comparative): Polymerisation of Propylene Oxide and CS2 with a DMC Catalyst Dried Under Argon and Activated in an Ar Atmosphere in a Semi-Batch CAOS Process with Addition of CS.SUB.2 .in Step β

[First Activation Stage, Step (α)]

[0208] A 970 mL pressure reactor fitted with a sparging stirrer was initially charged with a mixture of DMC catalyst (30.0 mg), toluene (175 mL) and CS.sub.2 (10.0 g) and the reaction mixture was stirred (800 rpm) for 30 min at 130° C.

[Second Activation Stage, Step (β)]

[0209] A pressure of 2 bar of Ar was established. 10.0 g of CS.sub.2 were metered in via an HPLC pump (2.0 mL/min) with continued stirring and a slight temperature drop was apparent. Once a temperature of 130° C. had been reestablished, 2.5 g of propylene oxide were metered in using an HPLC pump (1.0 mL/min) and the reaction mixture was stirred (800 rpm) for 20 min. Subsequently, two further portions of propylene oxide of 2.5 g each were metered in by means of the HPLC pump (1.0 mL/min) and the reaction mixture was stirred (800 rpm) for 20 min in each case. The occurrence of a brief increase in evolution of heat in the reactor during this time confirmed the activation of the catalyst.

[Polymerisation Stage, Step (γ)]

[0210] The temperature was readjusted to 110° C. and a further 77.4 g of propylene oxide were metered in by means of an HPLC pump (1.25 mL/min) with stirring, with continued stirring of the reaction mixture (800 rpm). Three minutes after commencement of the addition of propylene oxide (3.0), 4.5 g of dipropylene glycol were metered in by means of a separate HPLC pump (0.18 mL/min) with stirring. After the addition of propylene oxide had ended, the reaction mixture was stirred at 110° C. for a further 30 min. The reaction was stopped by cooling the reactor with ice water, the positive pressure was released. No product was obtained.

TABLE-US-00002 TABLE 2 Overview of results for preparation of polyether thiocarbonate polyols with variation of the time of addition of carbon disulfide in a semi-batch CAOS process Time of Proportion addition n(PO)/ Selectivity of sulfur Refractive Ex- of CS.sub.2 n(CS2) for PETC.sup.b) S(—S(C═S)—O) S(—S(C═O)—) atoms index ample.sup.a) [−] [mol/mol] [mol %] [mol %] [mol %] [wt %] [−] 7 [step γ] 11.1 ≥99% 93.1 6.9 2.1 1.47 8 [step α] 11.1 No product was obtained. (comp.) 9 [step β] 11.1 No product was obtained. (comp.) .sup.a)comp.: comparative example, PETC: .sup.b)linear polyether thiocarbonate polyol,

[0211] Example 7 and comparative examples 8-9 show that in the case of addition of carbon disulfide in the polymerization stage (step γ) (example 7) the carbon disulfide is incorporated into the polymer while by contrast in the case of addition of carbon disulfide only during the first activation stage (step α) (comparative example 8) or the second activation stage (step β) (comparative example 9) no product is obtained. Likewise, the refractive index of the polymer increases with an increased proportion of incorporated carbon disulfide in the polyether thiocarbonate polyol (examples 7). The linear polyether thiocarbonate polyol is likewise obtained in high selectivity over cyclic thiocarbonate and the obtained polyol has a higher ratio of thiocarbonate groups (—S(C═S)—) to thiocarbonate groups (—S(C═O)—) (examples 7).