METHOD FOR PRODUCING POLYALKYLENE GLYCOL, VISCOSITY INDEX IMPROVER, LUBRICATING OIL COMPOSITION, AND METHOD FOR PRODUCING LUBRICATING OIL COMPOSITION

Abstract

The method for producing a polyalkylene glycol of the present invention is a method for producing a polyalkylene glycol, including performing a polymerization reaction of an alkylene oxide with a composite metal catalyst, the polymerization reaction being performed in the presence of an organic solvent in an amount of 10 to 90 mass % based on the polyalkylene glycol to be produced.

Claims

1. A method for producing a polyalkylene glycol, the method comprising performing a polymerization reaction of an alkylene oxide with a composite metal catalyst, the polymerization reaction being performed in the presence of an organic solvent in an amount of 10 to 90 mass % based on the polyalkylene glycol to be produced.

2. The method for producing a polyalkylene glycol according to claim 1, wherein the organic solvent comprises an ether compound.

3. The method for producing a polyalkylene glycol according to claim 2, wherein the ether compound is selected from the group consisting of a dialkyl ether, an alkyl group of which is a branched or linear alkyl group having 5 to 12 carbon atoms; a dialkyl diether, an alkyl group of which is a branched or linear alkyl group having 5 to 12 carbon atoms; a polyether, which is an alkyl ether of a trihydric or higher polyhydric alcohol, an alkyl group of which is a branched or linear alkyl group having 5 to 12 carbon atoms; a polyvinyl ether; and a polyalkylene glycol ether having an end hydroxyl group that is etherified with a linear or branched alkyl group having 1 to 5 carbon atoms.

4. The method for producing a polyalkylene glycol according to claim 3, wherein the ether compound is selected from the group consisting of a polyvinyl ether; and a polyalkylene glycol ether having an end hydroxyl group that is etherified with a linear or branched alkyl group having 1 to 5 carbon atoms.

5. The method for producing a polyalkylene glycol according to claim 1, wherein the composite metal catalyst is a composite metal cyanide complex catalyst.

6. The method for producing a polyalkylene glycol according to claim 5, wherein the composite metal cyanide complex catalyst comprises an alcohol compound as an organic ligand.

7. The method for producing a polyalkylene glycol according to claim 1, wherein the polyalkylene glycol is produced by performing polymerization reaction with the composite metal catalyst present in a mixture of the alkylene oxide and an initiator, which is a compound having one or more hydroxyl group.

8. The method for producing a polyalkylene glycol according to claim 7, wherein the compound having one or more hydroxyl group is a polyalkylene glycol having a weight average molecular weight that is lower than the polyalkylene glycol to be produced.

9. The method for producing a polyalkylene glycol according to claim 1, wherein the polyalkylene glycol produced has a weight average molecular weight of 20,000 or more.

10. A viscosity index improver, comprising a polyalkylene glycol that is produced by the production method according to claim 9.

11. A lubricating oil composition, comprising the polyalkylene glycol that is produced by the production method according to claim 1.

12. A method for producing a lubricating oil composition, the method comprising blending a mixture comprising the polyalkylene glycol that is obtained by the production method according to claim 1 and the organic solvent.

Description

EXAMPLES

[0071] The present invention will be described further specifically with reference to examples below, but the present invention is not limited to the examples.

[0072] The measurement of the properties was performed according to the following procedures.

(1) Weight Average Molecular Weight (Mw)

[0073] The weight average molecular weight was measured with gel permeation chromatography (GPC). In the GPC, the measurement was performed by using two columns of TSKgel Super Multipore HZ-M, produced by Tosoh Corporation, and tetrahydrofuran as an eluent with a refractive index detector, and the weight average molecular weight was obtained with the standard polystyrene.

[Preparation of Composite Metal Complex Catalyst]

[0074] An aqueous solution containing 10.2 g of zinc chloride and 10 g of water was placed in a 500 mL flask. Subsequently, while stirring the content of the flask and retaining the content at 40° C., an aqueous solution containing 4.3 g of potassium hexacyanocobaltate and 75 g of water was added dropwise to the flask over 30 minutes. After completing the dropwise addition, the mixture in the flask was stirred for 30 minutes, and then a mixture containing 80 g of tert-butyl alcohol, 80 g of water, and 0.6 g of polypropylene glycol (the both ends of which were hydroxyl groups) having a weight average molecular weight of 2,000 was further added to the flask, followed by stirring at 40° C. for 30 minutes and at 60° C. for further 60 minutes. The mixture thus obtained was filtered under increased pressure with a circular filter plate having a diameter of 125 mm and quantitative filter paper for fine particles, so as to separate a solid matter in a slurry form containing a composite metal cyanide complex catalyst.

[0075] Subsequently, the resulting solid matter was placed in a flask, to which a mixture of 36 g of tert-butyl alcohol and 84 g of water was added, followed by stirring for 30 minutes, and then the mixture was filtered under increased pressure to provide a solid matter in a slurry form. The resulting solid matter was placed in a flask, to which a mixture of 108 g of tert-butyl alcohol and 12 g of water was added, followed by stirring for 30 minutes, so as to provide a liquid containing a composite metal cyanide complex catalyst dispersed in a tert-butyl alcohol-water mixed solvent. The liquid was mixed with 120 g of polypropylene glycol (the both ends of which were hydroxyl groups) having a weight average molecular weight of 2,000 as an initiator, and then the volatile components were distilled off under reduced pressure at 80° C. for 3 hours and at 115° C. for further 3 hours, so as to provide a mixture containing the initiator and the composite metal cyanide complex catalyst.

Example 1

[Production of PAG]

[0076] In a 200 mL autoclave, 10.05 g of the mixture containing the initiator and the composite metal cyanide complex catalyst (polypropylene glycol: 10 g, composite metal cyanide complex catalyst: 0.05 g) and 28 g of polyethyl vinyl ether (.sub.weight average molecular weight: 362) (30 mass % based on the PAG to be produced) as an organic solvent were charged. After replacing the interior of the autoclave with nitrogen, 40 g of propylene oxide was added thereto, and the internal temperature was increased to 130° C. After confirming that the internal pressure of the autoclave was decreased, 43 g of propylene oxide was added at a flow rate of 3 mL/min After the addition, the reaction was performed at the internal temperature retained to 130° C. until the internal pressure of the autoclave reached 0.1 MPa or less. After the reaction, 1.5 g of sodium methoxide as a catalyst deactivator was added thereto, the mixture was stirred for 1 hour, then 1N sulfuric acid was added thereto in an amount of 1.5 times equivalent amount based on sodium, and the mixture was neutralized at 120° C. for 2 hours, then dehydrated at 120° C. for 2 hours, and then filtered. After the filtration, 2.0 wt % of synthetic magnesium silicate as an absorbent was added, and the mixture was processed at 120° C. for 30 minutes, then dehydrated at 20 Torr for 2 hours, and then filtered, so as to provide 120 g of a mixture of PAG (92 g) produced through the aforementioned reaction and the organic solvent. Only the PAG was extracted from the resulting mixture and measured for the weight average molecular weight Mw of the PAG by the above-described method, and thus Mw was 30,000.

Example 2

[0077] The same procedures as in Example 1 were performed except that the amount of the organic solvent used in the polymerization reaction was 65 g, which was 70 mass % based on the PAG to be produced. Only the PAG was extracted from the resulting mixture and measured for the weight average molecular weight Mw of the PAG by the above-described method, and thus Mw was 30,000.

Example 3

[0078] The same procedures as in Example 1 were performed except that the amount of the organic solvent used in the polymerization reaction was 46 g, which was 50 mass % based on the PAG to be produced. Only the PAG was extracted from the resulting mixture and measured for the weight average molecular weight Mw of the PAG by the above-described method, and thus Mw was 30,000.

Example 4

[0079] The same procedures as in Example 1 were performed except that the amount of the organic solvent used in the polymerization reaction was 30 g, which was 30 mass % based on the PAG to be produced, and 15.08 g of the mixture containing the initiator and the composite metal cyanide complex catalyst (polypropylene glycol: 15 g, composite metal cyanide complex catalyst: 0.08 g) was used. Only the PAG was extracted from the resulting mixture and measured for the weight average molecular weight Mw of the PAG by the above-described method, and thus Mw was 20,000.

Comparative Example 1

[0080] Polymerization reaction was performed in the same manner as in Example 1 except that the organic solvent was not used. After the addition of the whole amount of propylene oxide, the reaction was performed while retaining the internal temperature at 130° C. as similar to Example 1, but the stirring blade was stopped in the course of the reaction, and the polymerization reaction was difficult to continue.

Comparative Example 2

[0081] Polymerization reaction was performed in the same manner as in Example 1 except that the amount of the organic solvent used in the polymerization reaction was 4.6 g, which was 5 mass % based on the PAG to be produced.

[0082] After the addition of the whole amount of propylene oxide, the reaction was performed while retaining the internal temperature at 130° C. as similar to Example 1, but the stirring blade was stopped in the course of the reaction, and the polymerization reaction was difficult to continue.

Comparative Example 3

[0083] The same procedures as in Example 1 were performed except that the amount of the organic solvent used in the polymerization reaction was 88 g, which was 95 mass % based on the PAG to be produced. In Comparative Example 3, the polymerization was not completed due to the prolonged reaction time.

[0084] As described in the foregoing, in Examples 1 to 3, PAG having a high molecular weight was able to be efficiently produced by performing the polymerization reaction in the presence of the organic solvent in an amount of 10 to 90 mass %. In Comparative Examples 1 and 2 with an amount of the organic solvent of less than 10 mass %, on the other hand, the reaction was not able to be continued due to the excessively high viscosity in the course of the reaction, and thus PAG having a high molecular weight was not able to be efficiently produced. In the case where the amount of the organic solvent exceeded 90 mass % as in Comparative Example 3, the polymerization was not completed even by prolonging the reaction time, and thus PAG having a high molecular weight was not able to be efficiently produced.

INDUSTRIAL APPLICABILITY

[0085] The polyalkylene glycol produced by the present invention is blended in a lubricating oil composition used in a refrigerator, an internal-combustion engine, a gear system, a bearing system, a transmission system, a shock absorber, and the like, and used, for example, as a viscosity index improver. The polyalkylene glycol can also be used as a raw material for urethane constituting an adhesive, a sealant, and the like.