JPH07109479A - Viscosity index improver for lubricating oil - Google Patents

Abstract

PURPOSE:To obtain a lubricating oil improved in viscosity index, shear stability and low-temperature flow by adding a di(2-ethylhexyl) fumarate/1-octene/styrene copolymer of a weight-average molecular weight of 5000 or above to a lubricating oil. CONSTITUTION:1mol of di(2-ehylhexyl) fumarate is copolymerized with 0.15-0.5mol of 1-octene to produce a copolymer of a weight-average molecular weight of 5000 or above. It is also possible that the components of this copolymer and 0.3mol or below desirably 0.2-0.01mol of styrene are copolymerized to form a terpolymer of a higher molecular weight. The improver mentioned in this title contains this polymer as the effective component and is added desirably in an amount of 5-30 pts.wt. per 100 pts.wt. base oil such as a mineral oil. This improver can impart well-balanced performances to a lubricating oil.

Description

Detailed Description of the Invention

[0001]

The present invention relates to the viscosity index (V
I) The improving agent, and more specifically, to the lubricating oil viscosity index improving agent containing a fumarate ester copolymer as an active ingredient.

[0002]

2. Description of the Related Art Lubricating oils are usually added with a viscosity index improver in order to suppress fluctuations in viscosity due to temperature changes. As such a viscosity index improver, polymethacrylate, ethylene-propylene copolymer and the like have been widely used. However, with polymethacrylate, if the effect of improving the viscosity index is increased (the molecular weight is increased), the shear stability will decrease. In addition, in the ethylene-propylene copolymer, the low-temperature fluidity of the base oil is lowered at an addition amount such that the effect of improving the viscosity index is obtained. Conversely, if the addition amount is reduced, the low-temperature fluidity is improved. It has a drawback that the effect of improving the viscosity index is reduced.

Therefore, the present invention aims to provide an excellent viscosity index improver for lubricating oils.

[0004]

As a result of repeated studies on additives for lubricating oils, the present inventors have found that a copolymer of an α-olefin having a specific carbon number and a specific fumaric acid diester is an active ingredient. The present inventors have found that the viscosity index improver as described above is excellent in the effect of improving the viscosity index of a lubricating oil, and that it is also effective as a thickener, and thus arrived at the present invention.

That is, the present invention relates to (A) di (2-fumaric acid).
Ethylhexyl) and (B) 1-octene to (A) 1
A copolymer obtained by polymerizing 0.15 to 0.5 mol of (B) with respect to mol, and having a weight average molecular weight of 50.
Provided is a lubricating oil viscosity index improver containing as an active ingredient a copolymer of 00 or more.

The copolymer of di (2-ethylhexyl) fumarate and 1-octene used in the present invention contains (B) 1-octene per 1 mol of (A) di (2-ethylhexyl) fumarate. 0.15-0.5 mol, preferably 0.2-0.3
Included in molar ratio. If the amount of (B) is less than this, bubbles tend to be generated when the copolymer is sheared, and the foam breakage tends to be poor. If it is more than this, the foam breaks well but shear stability decreases. . The copolymer may be of any copolymer type, and may be, for example, a random, block, or graft copolymer. The weight average molecular weight (Mw) of the copolymer is 5,000 or more, and 20,000 or more is practical. The higher the weight average molecular weight, the higher the effect of improving the viscosity index, which is preferable, but it is usually 100,000.
Use the following:

Japanese Patent Publication No. 62-16996 discloses a lubricating oil for the purpose of improving the oiliness and wear resistance of the lubricating oil.
C ₄ alpha-olefin and α of -C _60, adding a copolymer of dialkyl esters of β- unsaturated carboxylic acid is disclosed. However, the above-mentioned copolymer of 1-octene and di (2-ethylhexyl) fumarate is not specifically described here.

Such a copolymer can be produced by a known polymerization method. That is, di (2-ethylhexyl) fumarate and 1-octene are polymerized by a conventional method in the presence of a reaction initiator, for example, a radical polymerization initiator such as benzoyl peroxide (BPO). The polymerization method may be either a solution polymerization method (a known solvent such as benzene, toluene, xylene, or tetrahydrofuran can be used) or a bulk polymerization method (no solvent). To obtain a high molecular weight copolymer, the reaction temperature is preferably 50 to 70 ° C, more preferably about 60 ° C. In addition, in order to improve the yield,
It is recommended to react for 7 days. The reaction initiator is preferably BPO which decomposes at 60 ° C. Furthermore, it is preferable to carry out without solvent. Also, a suitable solvent system such as tetrahydrofuran-
A higher molecular weight product can be obtained by reprecipitating with an acetone system.

The above copolymer further contains 0.3% or less, preferably 0.2 to 0.01 mol, of (C) styrene per 1 mol of (A) for the purpose of increasing the molecular weight. Can be included in. However, if the amount of styrene is too large, the solubility in the base oil will deteriorate. Further, as other copolymerization component, α-methylstyrene, 4-methylstyrene and the like can be contained in an amount of 0.3 mol or less per 1 mol of (A).

The lubricant viscosity index improver of the present invention contains the above-mentioned copolymer as an active ingredient. In addition to the above copolymer, polymethacrylate or the like may be added.

The addition amount of the viscosity index improver of the present invention in the lubricating oil varies depending on the use of the lubricating oil, but is usually preferably 2 to 50 parts by weight, more preferably 100 parts by weight of the base oil such as mineral oil. 5 to 30 parts by weight can be added.

The lubricating oil to which the viscosity index improver of the present invention is added can be used as engine oil, turbine oil, gear oil and the like.

[0013]

The present invention will be further described by the following examples.

The various evaluation tests carried out in the following examples were carried out as follows. In all the tests, the sample oil was prepared by adding 10% by weight of the active ingredient of the viscosity index improver to the base oil. Also, as the base oil, 1
Mineral oil with a viscosity of 00 ° C. of 4.88 mm ² / s was used. (1) Oxidation stability test (Indiana Stirring Oxidation Te
st, ISOT) JIS K 2514-1982 (lubricating oil oxidation stability test method). That is, a magnetic stirrer, a glass rod (varnish rod) and a steel / copper plate catalyst were placed in a glass container (beaker shape) and the glass container was covered. Sample oil 2
50 ml was added and heated at 165.5 ° C. for 48 hours with stirring.

When the lacquer / sludge adhering to the glass rod or the glass container was visually observed, good results were obtained for Examples 1 to 4. (2) Shear stability test (ultrasonic method) It was conducted in accordance with the ultrasonic method in JPI-5S-29-88 (lubricating oil shear stability test method). That is, 30 ml of sample oil was placed in a beaker, the tip of a horn of an ultrasonic oscillator was placed below the oil surface, and ultrasonic irradiation was performed. Output 13.6
Irradiation was performed at V and oil temperature of 40 ° C. for 30 minutes.

The viscosities (100 ° C. and 40 ° C.) of fresh oil (sample oil before treatment) and shear oil (sample oil after shear treatment) were measured, and the viscosity index (VI) was calculated. Further, the VI change of the sheared oil with respect to the fresh oil was examined (the smaller the numerical value (absolute value), the better the shear stability).
In addition, since minute bubbles are generated during the shearing test, disappearance of bubbles (stopping bubbles) after the shearing was stopped was visually observed. If the defoaming is poor, it causes inconvenience when added to the lubricating oil. (3) Low-temperature fluidity test It was performed in accordance with ASTM D 2983-80 (low-temperature viscosity measurement method for lubricating oil by Brookfield viscometer). That is, 30 ml of sample oil was put into a test tube, and the spindle was immersed to a certain depth. The spindle was rotated at a constant speed and the viscosity under low shear rate (Brookfield (BF) viscosity) was measured. The oil temperature was -20 degreeC and -40 degreeC. Example 1 In a 500 ml separable flask equipped with a condenser tube with a ball and a magnetic stirrer, di (2-ethylhexyl) fumarate was added.
233.9 g (687 mmol), 1-octene 22.9
g (204 mmol) and styrene 10.8 g (10
4 mmol) was added and nitrogen was flushed in for 1 hour with vigorous stirring. Put the reaction vessel in an oil bath and raise the temperature to 60 ° C.
Kept at 3.23g of benzoyl peroxide (BPO)
(13.3 mmol) was added, and the mixture was stirred for 7 days. Then, the temperature was raised to 150 ° C. and the light components were distilled off to obtain 256.3 g of a polymer. Yield 98%.

The obtained copolymer was subjected to the above-mentioned various evaluation tests as an active ingredient of a viscosity index improver. The results are shown in Table 1. Example 2 A 500 ml separable flask equipped with a condenser tube with a ball and a magnetic stirrer was charged with di (2-ethylhexyl) fumarate.
202.1 g (594 mmol) and 1-octene 1
7.0 g (151 mmol) was added and nitrogen was flushed in for 1 hour with vigorous stirring. Put the reaction vessel in an oil bath and keep the temperature at 60 ° C, and add benzoyl peroxide (BP
O) (3.16 g, 13.0 mmol) was added and the mixture was stirred for 5 days. Then, the temperature was raised to 150 ° C. and the light components were distilled off to obtain 217.8 g of a polymer. Yield 9
8%.

The obtained copolymer was subjected to the above-mentioned various evaluation tests as a viscosity index improver active ingredient. The results are shown in Table 1. Example 3 A 500 ml separable flask equipped with a condenser tube with a ball and a magnetic stirrer was charged with di (2-ethylhexyl) fumarate.
160.7 g (472 mmol) and 1-octene 1
0.7 g (95 mmol) was added and flushed with nitrogen for 1 hour with vigorous stirring. Put the reaction vessel in an oil bath and keep the temperature at 60 ° C, and add benzoyl peroxide (BP
O) (1.38 g, 5.7 mmol) was added, and the mixture was stirred for 3 days. Then, the temperature was raised to 150 ° C. and the light components were distilled off to obtain 171.2 g of a polymer. Yield 99
%.

The obtained copolymer was subjected to the above various evaluation tests as an active ingredient of a viscosity index improver. The results are shown in Table 1. Example 4 100 g of the polymer obtained in Example 3 was dissolved in 200 ml of tetrahydrofuran (THF). This solution was poured into 800 ml of acetone for reprecipitation. Further, the obtained precipitate was reprecipitated in a mixed solvent system of 100 ml of THF and 300 ml of acetone. The obtained precipitate was dried in air for 2 days to obtain 35 g of a polymer.

The obtained copolymer was subjected to the above various evaluation tests as an active ingredient of a viscosity index improver. The results are shown in Table 1. Comparative Example 1 Di (2-ethylhexyl) fumarate was placed in a 500 ml separable flask equipped with a condenser tube with balls and a magnetic stir bar.
149.1 g (438 mmol) and 1-octene 9.
6 g (86 mmol) was added and with vigorous stirring 1
It was flushed with nitrogen for an hour. Put the reaction vessel in an oil bath and keep the temperature at 80 ° C, and use benzoyl peroxide (BPO).
6.36 g (26.3 mmol) was added and the mixture was stirred for 2 days. Then, the temperature was raised to 150 ° C. and the light components were distilled off to obtain 152.6 g of a polymer. Yield 93
%.

The resulting copolymer was subjected to the above-mentioned various evaluation tests as a viscosity index improver active ingredient. The results are shown in Table 1. Comparative Example 2 In a 500 ml separable flask equipped with a condenser tube with balls and a magnetic stirrer, di (2-ethylhexyl) fumarate was added.
175.1 g (514 mmol) was added and flushed with nitrogen for 1 hour with vigorous stirring. The reaction vessel was placed in an oil bath and the temperature was kept at 60 ° C., 4.48 g (18.5 mmol) of benzoyl peroxide (BPO) was added, and
It was stirred for a day. Then, the temperature was raised to 150 ° C. and the light components were distilled off to obtain 176.0 g of a polymer.
Yield 98%.

The obtained polymer was subjected to the above various evaluation tests as an active ingredient of a viscosity index improver. The results are shown in Table 1. Comparative Example 3 In a 500 ml separable flask equipped with a condenser tube with balls and a magnetic stirrer, di (2-ethylhexyl) fumarate was added.
145.5 g (427 mmol) and styrene 8.9
g (85 mmol) was added and flushed with nitrogen for 1 hour with vigorous stirring. The reaction vessel was placed in an oil bath to keep the temperature at 60 ° C., and benzoyl peroxide (BPO) 2.
34 g (9.7 mmol) was added and the mixture was stirred for 3 days. Then, the temperature was raised to 150 ° C. and the light components were distilled off to obtain 156.0 g of a polymer. Yield 98%.

The obtained copolymer was subjected to the above-mentioned various evaluation tests as an active ingredient of a viscosity index improver. The results are shown in Table 1. Comparative Example 4 In a 500 ml separable flask equipped with a condenser tube with balls and a magnetic stir bar, di (2-ethylhexyl) fumarate was added.
168.1 g (494 mmol), 1-octene 33.4
g (298 mmol) and 7.7 g (74 mmol) of styrene were added and nitrogen was flushed in for 1 hour with vigorous stirring. The reaction vessel was put in an oil bath and the temperature was kept at 60 ° C., and 4.65 g of benzoyl peroxide (BPO) (1
(9 mmol) was added and the mixture was stirred for 5 days. Then, the temperature was raised to 150 ° C. and the light components were distilled off to obtain 198.0 g of a polymer. Yield 93%.

The obtained copolymer was subjected to the above-mentioned various evaluation tests as an active ingredient of a viscosity index improver. The results are shown in Table 1. Comparative Example 5 In a 500 ml separable flask equipped with a condenser tube with balls and a magnetic stirrer, di (2-ethylhexyl) fumarate was added.
142.0 g (417 mmol) and 1-octene 5.
1 g (45 mmol) was added and with vigorous stirring 1
It was flushed with nitrogen for an hour. Put the reaction vessel in an oil bath and keep the temperature at 60 ° C, and use benzoyl peroxide (BPO).
1.01 g (4.3 mmol) was added, and the mixture was stirred for 3 days. Then, the temperature was raised to 150 ° C. and the light components were distilled off to obtain 147.3 g of a polymer. Yield 99%.

The resulting copolymer was subjected to the above various evaluation tests as an active ingredient of a viscosity index improver. The results are shown in Table 1. Comparative Example 6 In a 500 ml separable flask equipped with a condenser tube with balls and a magnetic stirrer, di (2-ethylhexyl) fumarate was added.
156.9 g (461 mmol), 1-octene 15.5
g (138 mmol) and styrene 25.0 g (24
(0 mmol) was added and nitrogen was flushed in for 1 hour with vigorous stirring. Put the reaction vessel in an oil bath and raise the temperature to 60 ° C.
Kept at 1.81 g of benzoyl peroxide (BPO)
(7.5 mmol) was added, and the mixture was stirred for 7 days. Then, the temperature was raised to 150 ° C. and the light components were distilled off to obtain 192.4 g of a polymer. Yield 97%.

The obtained copolymer was subjected to the above-mentioned various evaluation tests as an active ingredient of a viscosity index improver. The results are shown in Table 1. Comparative Example 7 Polymethacrylate (trade name: Plexol 1019, ROHM
Andhase (manufactured by Rohm & Haars) was used as the viscosity index improver active ingredient in the above various evaluation tests. The results are shown in Table 1. Comparative Example 8 Ethylene-Propylene Copolymer (Brand Name: Lucant DA-2
000B, manufactured by Mitsui Petrochemical Co., Ltd.) was subjected to the above-mentioned various evaluation tests as a viscosity index improver active ingredient. The results are shown in Table 1.
Shown in. Comparative Example 9 140.2 g (8) of diethyl maleate was placed in a 500 ml three-necked flask equipped with a condenser tube with balls and a magnetic stirrer.
14 mmol), an α-olefin having 18 carbon atoms 81.
6 g (323 mmol) and 73.2 g (326 mmol) of α-olefin having 16 carbon atoms were added, and nitrogen was flushed for 1 hour with vigorous stirring. The reaction vessel was placed in an oil bath and the temperature was kept at 160 ° C., and 8.32 g (56.9 mmol) of di-tert-butyl peroxide was added in several portions and the mixture was stirred for 3 hours. Then, the pressure was reduced to 20 mmHg, and the light components were distilled off to obtain 279.9 g of a polymer.
Yield 92%.

The obtained copolymer was subjected to the above-mentioned various evaluation tests as an active ingredient of a viscosity index improver. The results are shown in Table 1. Comparative Example 10 In a 500 ml three-necked flask equipped with a cooling tube with balls and a magnetic stirrer, 123.5 g of disec-butyl maleate.
(541 mmol), α-olefin 5 having 18 carbon atoms
5.4 g (219 mmol) and α-containing 16 carbon atoms
48.6 g (217 mmol) of olefin was added and nitrogen was flushed in for 1 hour with vigorous stirring. The reaction vessel was put in an oil bath to keep the temperature at 160 ° C., 5.53 g (37.8 mmol) of di-tert-butyl peroxide was added in several portions, and the mixture was stirred for 3 hours. Then, the pressure was reduced to 20 mmHg, and the light components were distilled off to obtain 218.6 g of a polymer. Yield 94%.

The obtained copolymer was subjected to the above various evaluation tests as an active ingredient of a viscosity index improver. The results are shown in Table 1. Comparative Example 11 Di (2-ethylhexyl) fumarate 13 was added to a 500 ml three-necked flask equipped with a condenser tube with balls and a magnetic stirrer.
0.3 g (383 mmol), α-olefin having 18 carbon atoms 48.3 g (191 mmol) and carbon number 16
34.4 g (153 mmol) of α-olefin were added and nitrogen was flushed in for 1 hour with vigorous stirring. Put the reaction vessel in an oil bath and keep the temperature at 160 ℃.
3.86 g (26.4 mmol) of t-butyl peroxide
Was added in several times and stirred for 3 hours. Then 2
The light fraction was distilled off by reducing the pressure to 0 mmHg to obtain a polymer 201.
2 g was obtained. Yield 93%.

The obtained copolymer was subjected to the above various evaluation tests as an active ingredient of a viscosity index improver. The results are shown in Table 1.

[0030]

[Table 1] As shown in Table 1 above, in the case of the fumaric acid diester-1-octene copolymer having a small molecular weight (Comparative Example 1), the VI improving effect was hardly recognized. Also,
The fumaric acid diester-styrene copolymer (Comparative Example 3) has an effect of improving VI, but has poor shear stability and poor foam breakage. On the other hand, in the fumaric acid diester homopolymer (Comparative Example 2), although the VI improving effect is recognized, the shear stability is poor and the foam breakage is poor. Further, a copolymer having a too large amount of 1-octene (Comparative Example 4) tends to have low shear stability, and a too small amount (Comparative Example 5) has good shear stability but poor defoaming. Become. Further, Comparative Example 7 (conventional product) has poor shear stability, and Comparative Example 8 (conventional product) has poor low-temperature fluidity. On the other hand, even if the copolymers (Comparative Examples 9 to 11) shown in Table 1 of JP-B No. 62-16996 were used, the effect of improving VI was hardly recognized.

On the other hand, it can be seen that all the copolymers of the examples are excellent in the effect of improving the viscosity index, shear stability and low temperature fluidity.

[0032]

INDUSTRIAL APPLICABILITY The viscosity index improver of the present invention is suitable as a viscosity index improver for lubricating oils because it has a well-balanced effect of improving the viscosity index, shear stability and low temperature fluidity.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication location C10N 40:25 (72) Inventor Tokashiki Toshihide Nishitsurugaoka 1-3 chome Oimachi Iruma-gun Saitama No. 1 Tonen Co., Ltd. Research Institute

Claims (2)

[Claims] 1. (A) Di (2-ethylhexyl) fumarate
And (B) 1-octene, a copolymer obtained by polymerizing (B) 0.15 to 0.5 mol per 1 mol of (A), and having a weight average molecular weight of 5,000 or more. A lubricating oil viscosity index improver containing a copolymer as an active ingredient. 2. The lubricating oil according to claim 1, wherein the copolymer is a copolymer obtained by further polymerizing styrene (C) in an amount of 0.3 mol or less with respect to 1 mol of (A). Viscosity index improver.