METHOD FOR PRODUCING POLYALKYLENE OXIDE

Abstract

The present invention provides a production method for obtaining, by a simple method, a polyalkylene oxide whose molecular weight and polydispersity are controlled in the desired range.

The method for producing a polyalkylene oxide of the present disclosure comprises step 1 of performing a polymerization reaction of an alkylene oxide in the presence of a chain transfer agent to obtain a high-molecular-weight polyalkylene oxide; and step 2 of irradiating the high-molecular-weight polyalkylene oxide obtained in step 1 with radiation to obtain a polyalkylene oxide; wherein the amount of the chain transfer agent is 800 mass ppm or more relative to the alkylene oxide, and the high-molecular-weight polyalkylene oxide has a viscosity in a 1 mass % aqueous solution of 6000 mPas or less.

Claims

1. A method for producing a polyalkylene oxide, comprising step 1 of performing a polymerization reaction of an alkylene oxide in the presence of a chain transfer agent to obtain a high-molecular-weight polyalkylene oxide; and step 2 of irradiating the high-molecular-weight polyalkylene oxide obtained in step 1 with radiation to obtain a polyalkylene oxide; wherein the amount of the chain transfer agent is 800 mass ppm or more relative to the alkylene oxide, and the high-molecular-weight polyalkylene oxide has a viscosity in a 1 mass % aqueous solution of 6000 mPa.Math.s or less.

2. The method for producing a polyalkylene oxide according to claim 1, wherein the chain transfer agent comprises an alcohol compound.

3. The method for producing a polyalkylene oxide according to claim 1, wherein the alcohol compound is at least one member selected from the group consisting of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, and t-butanol.

4. The method for producing a polyalkylene oxide according to claim 2, wherein the alcohol compound is at least one member selected from the group consisting of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, and t-butanol.

5. The method for producing a polyalkylene oxide according to claim 1, wherein the polyalkylene oxide obtained in step 2 has a mass average molecular weight of 100000 to 2500000, and a polydispersity of 5 or more.

6. The method for producing a polyalkylene oxide according to claim 2, wherein the polyalkylene oxide obtained in step 2 has a mass average molecular weight of 100000 to 2500000, and a polydispersity of 5 or more.

7. The method for producing a polyalkylene oxide according to claim 3, wherein the polyalkylene oxide obtained in step 2 has a mass average molecular weight of 100000 to 2500000, and a polydispersity of 5 or more.

8. The method for producing a polyalkylene oxide according to claim 4, wherein the polyalkylene oxide obtained in step 2 has a mass average molecular weight of 100000 to 2500000, and a polydispersity of 5 or more.

Description

EXAMPLES

[0066] The present disclosure is described in more detail below by means of examples; however, the present disclosure is not limited to the embodiments of the examples.

Production Example 1: Production of Zinc Catalyst

[0067] After the inside of a round-bottom flask with an inner diameter of 80 mm and a capacity of 500 mL, equipped with a cooler, a dropping funnel, a nitrogen gas inlet tube, and a stirring blade with four (45° inclined) paddle blades with a blade diameter of 53 mm as a stirrer, was replaced with nitrogen, 87.1 g of n-hexane and 9.90 g of diethylzinc (Et.sub.2Zn) were added to this flask. While the inner temperature of the flask was maintained at 20° C., and the inside of the flask was stirred at a tip peripheral speed of 0.97 m/sec (stirring speed: 350 rpm), 11.03 g (0.240 mol) of ethyl alcohol (EtOH) was added dropwise at 0.2 g/min as the first stage to perform a reaction, thus obtaining a reaction solution. Subsequently, as the second stage, a mixture comprising 6.49 g (0.072 mol) of 1,4-butanediol (1,4-BDO) and 13.27 g (0.288 mol) of ethyl alcohol was added dropwise at a rate of 0.2 g/min into the above reaction solution that had been cooled to 10° C. After completion of the dropwise addition, the inside of the flask was increased to 30° C., and then further reacted for 1 hour. Subsequently, the temperature was increased to 50° C. to perform a reaction for 1 hour. Thereafter, by distillation in which the flask was heated to 80° C., an unreacted component was removed. After the distillation, the inside of the flask was allowed to cool to room temperature; then, 52.4 g of n-hexane was added to the flask, followed by heating to 80° C., thus performing the second distillation. This operation was performed one more time, thus performing distillation a total of three times. Thereafter, the resultant was cooled and diluted with 264 g of n-hexane to obtain 297 g of a zinc catalyst with a zinc content of 1.8 mass %.

Production Example 2-1: Production of High-Molecular-Weight Polyalkylene Oxide

[0068] After the inside of a pressure-resistant reaction vessel with an inner diameter of 94 mm and a capacity of 1 L, equipped with a dropping funnel, a nitrogen gas inlet tube, and a stirring blade with an anchor-type paddle blade with a blade diameter of 47 mm as a stirrer, was replaced with nitrogen, 340 g of n-hexane was placed in this pressure-resistant reaction vessel, and 0.975 g (zinc equivalent: 0.0004 mol) of the zinc catalyst obtained in Production Example 1 was uniformly dispersed in this n-hexane to obtain a dispersion.

[0069] After 0.203 g (0.0034 mol) of isopropanol and 81 g (1.84 mol) of ethylene oxide were added as chain transfer agents to the dispersion, the vessel was tightly closed, and maintained at 40° C. While stirring the mixture, a polymerization reaction was performed.

[0070] In the polymerization reaction, the amount of the chain transfer agent is 2500 mass ppm relative to ethylene oxide.

[0071] The white product obtained by the polymerization reaction was separated by filtration, followed by drying under reduced pressure at 40° C. to give 81.0 g of a high-molecular-weight polyethylene oxide. The viscosity in a 1% aqueous solution of the obtained high-molecular-weight polyalkylene oxide was 5800 mPa.Math.s.

Production Example 2-2: Production of High-Molecular-Weight Polyalkylene Oxide

[0072] 81.0 g of a high-molecular-weight polyethylene oxide was obtained in the same manner as in Production Example 2-1, except that the chain transfer agent was changed to t-butanol, and the amount was changed to about 818 mass ppm relative to ethylene oxide.

[0073] The obtained high-molecular-weight polyalkylene oxide had a viscosity in a 1% aqueous solution of 3200 mPa.Math.s.

Production Example 2-3-1: Production of High-Molecular-Weight Polyalkylene Oxide

[0074] After the inside of a pressure-resistant reaction vessel with an inner diameter of 94 mm and a capacity of 1 L, equipped with a dropping funnel, a nitrogen gas inlet tube, and a stirring blade with an anchor-type paddle blade with a blade diameter of 47 mm as a stirrer, was replaced with nitrogen, 340 g of n-hexane was placed in this pressure-resistant reaction vessel, and 0.975 g (zinc equivalent: 0.0004 mol) of the zinc catalyst obtained in Production Example 1 was uniformly dispersed in this n-hexane to obtain a dispersion.

[0075] After 81 g (1.84 mol) of ethylene oxide was added to the dispersion, the vessel was tightly closed, and maintained at 40° C. While stirring the mixture, a polymerization reaction was performed.

[0076] The white product obtained by the polymerization reaction was separated by filtration, followed by drying under reduced pressure at 40° C. to give 81.0 g of a high-molecular-weight polyethylene oxide. The viscosity in a 1% aqueous solution of the obtained high-molecular-weight polyalkylene oxide was 13520 mPa.Math.s.

Production Example 2-3-2: Production of High-Molecular-Weight Polyalkylene Oxide

[0077] 81.0 g of a high-molecular-weight polyethylene oxide was obtained in the same manner as in Production Example 2-3-1. The viscosity in a 1% aqueous solution of the high-molecular-weight polyalkylene oxide was 12400 mPa.Math.s.

Production Example 2-4: Production of High-Molecular-Weight Polyalkylene Oxide

[0078] 81.0 g of a high-molecular-weight polyethylene oxide was obtained in the same manner as in Production Example 2-1, except that the amount of the chain transfer agent was changed to about 200 mass ppm relative to ethylene oxide. The viscosity in a 1% aqueous solution of the high-molecular-weight polyalkylene oxide was 11100 mPa.Math.s.

Production Example 2-5: Production of High-Molecular-Weight Polyalkylene Oxide

[0079] 81.0 g of a high-molecular-weight polyethylene oxide was obtained in the same manner as in Production Example 2-1, except that the chain transfer agent was changed to t-butanol and the amount was changed to about 236 mass ppm relative to ethylene oxide.

[0080] The viscosity in a 1% aqueous solution of the obtained high-molecular-weight polyalkylene oxide was 7720 mPa.Math.s.

Example 1

[0081] By irradiating 40.0 g of the high-molecular-weight polyethylene oxide obtained in Production Example 2-1 with 0.6 kGy of gamma ray, 40.0 g of the desired medium-molecular-weight polyethylene oxide was obtained. Gamma-ray irradiation was performed with high-molecular-weight polyethylene oxide powder contained in a nylon/low-density polyethylene bag, and Cobalt 60 gamma irradiation facility No. 1 (RIC1), produced by Radia Industry Co., Ltd., was used as an irradiation apparatus.

Example 2

[0082] 40.0 g of the desired medium-molecular-weight polyethylene oxide was obtained in the same manner as in Example 1, except that 0.7 kGy of gamma ray was emitted.

Example 3

[0083] By irradiating 40.0 g of the high-molecular-weight polyethylene oxide obtained in Production Example 2-2 with 5.0 kGy of gamma ray, 40.0 g of the desired medium-molecular weight polyethylene oxide was obtained.

Example 4

[0084] 40.0 g of the desired medium-molecular-weight polyethylene oxide was obtained in the same manner as in Example 3, except that 8.0 kGy of gamma ray was emitted.

Comparative Example 1

[0085] By irradiating 40.0 g of the high-molecular-weight polyethylene oxide obtained in Production Example 2-3-1 with 0.8 kGy of gamma ray, 40.0 g of the desired medium-molecular-weight polyethylene oxide was obtained.

Comparative Example 2

[0086] 40.0 g of the desired medium-molecular-weight polyethylene oxide was obtained in the same manner as in Comparative Example 1, except that 0.9 kGy of gamma ray was emitted.

Comparative Example 3

[0087] By irradiating 40.0 g of the high-molecular-weight polyethylene oxide obtained in Production Example 2-3-2 with 3.2 kGy of gamma ray, 40.0 g of the desired medium-molecular-weight polyethylene oxide was obtained.

Comparative Example 4

[0088] 40.0 g of the desired medium-molecular-weight polyethylene oxide was obtained in the same manner as in Comparative Example 3, except that 27.0 kGy of gamma ray was emitted.

Comparative Example 5

[0089] By irradiating 40.0 g of the high-molecular-weight polyethylene oxide obtained in Production Example 2-4 with 0.8 kGy of gamma ray, 40.0 g of the desired medium-molecular-weight polyethylene oxide was obtained.

Comparative Example 6

[0090] 40.0 g of the desired medium-molecular-weight polyethylene oxide was obtained in the same manner as in Comparative Example 5, except that 0.9 kGy of gamma ray was emitted.

Comparative Example 7

[0091] By irradiating 40.0 g of the high-molecular-weight polyethylene oxide obtained in Production Example 2-5 with 2.4 kGy of gamma ray, 40.0 g of the desired medium-molecular-weight polyethylene oxide was obtained.

Comparative Example 8

[0092] 40.0 g of the desired medium-molecular-weight polyethylene oxide was obtained in the same manner as in Comparative Example 7, except that 20.0 kGy of gamma ray was emitted.

TABLE-US-00001 TABLE 1 Viscosity in a 1% aqueous solution of high- molecular- Chain weight Gamma ray Medium-molecular-weight Example/ transfer polyethylene irradiation polyethylene oxide Comparative agent oxide amount Mw/Mn Example (ppm) (mPa .Math. s) (kGy) Mw Mn polydispersity Example 1 2500 5800 0.6 2391040 246762 9.7 Example 2 2500 5800 0.7 2058456 226204 9.1 Example 3 818 3200 5.0 179645 23456 7.7 Example 4 818 3200 8.0 175465 22513 7.8 Comparative 0 13520 0.8 1936620 624014 3.1 Example 1 Comparative 0 13520 0.9 1626898 390801 4.2 Example 2 Comparative 0 12400 3.2 1241492 338731 3.7 Example 3 Comparative 0 12400 27.0 165376 44970 3.7 Example 4 Comparative 200 11100 0.8 1917854 467769 4.1 Example 5 Comparative 200 11100 0.9 1580953 376417 4.2 Example 6 Comparative 236 7720 2.4 1019966 251132 4.1 Example 7 Comparative 236 7720 20.0 181439 51835 3.5 Example 8

[0093] Table 1 shows the measurement results of the mass average molecular weight (Mw), number average molecular weight (Mn), and polydispersity (Mw/Mn) of a medium-molecular-weight polyethylene oxide obtained in each of the Examples and Comparative Examples. Table 1 indicates that by obtaining a high-molecular-weight polyalkylene oxide having a viscosity in a 1 mass % aqueous solution of 6000 mPa.Math.s or less, in which the amount of the chain transfer agent was set to 800 mass ppm or more relative to the alkylene oxide, and treating the high-molecular-weight polyalkylene oxide with gamma ray, a medium-molecular-weight polyalkylene oxide that had a polydispersity of 5 or more although it had a medium molecular weight was generated.

[0094] The following methods were used for various evaluation methods.

Mass Average Molecular Weight and Polydispersity

[0095] The mass average molecular weight and polydispersity of polyethylene oxide were measured by gel permeation chromatography.

[0096] Specifically, 0.02 g of polyethylene oxide was added to 40 mL of a 0.19M sodium nitrate aqueous solution, followed by dissolution for 3 hours to obtain a solution. The solution was filtered through a 0.8 μm membrane filter, and the obtained filtrate was analyzed by gel permeation chromatography (HLC-8220GPC produced by Tosoh Corporation, guard column: TSKgel guardcolumn PWXL). In this measurement, TSKgel G6000PWXL, TSKgel GMPWXL, and TSKgel G3000PWXL were used as size exclusion columns; the mobile phase was a 0.20 M sodium nitrate aqueous solution; the flow rate was 0.5 mL/min; the column temperature was 40° C.; the differential refractometer temperature was 40° C.; the injection volume was 500 pL; and the measurement time was 90 minutes. Separately, by using a polyethylene oxide standard sample having a known weight average molecular weight, number average molecular weight, and polydispersity, the measurement was performed in a similar manner to form a calibration curve, and the mass average molecular weight, number average molecular weight, and polydispersity of polyethylene oxides having a LogM in the range of 3.5 to 7.2 were calculated based on the calibration curve.

Viscosity in 1% Aqueous Solution

[0097] 6 g of a polyethylene oxide and 125 mL of isopropanol were added to a 1 L beaker, and 594 g of ion exchange water was added under stirring the mixture at 300 to 400 rpm using a stirring blade, followed by stirring for one minute. Thereafter, the stirring speed was changed to 60 rpm, and the stirring was continued for an additional 3 hours to obtain an aqueous solution of 1% polyethylene oxide. The aqueous solution was maintained at 25° C., and the viscosity was measured using a rotational viscometer (Brookfield “RVDV-II+”). This value was defined as the viscosity in a 1% aqueous solution.