JPH08127789A - Lubricating oil composition - Google Patents

Abstract

PURPOSE: To improve the adsorption per unit area, coefficient of friction, and viscosity index by incorporating bis type and mono type alkenylsuccinimides and a particular polydimethylsiloxane into a base oil. CONSTITUTION: A bis type alkenylsuccinic acid with the average mol.wt. of the alkenyl group being 1000 to 1500, a mono type alkenylsuccinic acid with the average mol.wt. of the alkenyl group being 2000 to 2500, a low-mol.wt. polydimethylsiloxane having a kinematic viscosity of 10 to 100cSt, and a high- mol.wt. polydimethylsiloxane having a kinematic viscosity of 5000 to 20000cSt are incorporated as an additive into a base oil having a kinematic viscosity (100 deg.C) of not less than 3cSt.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a lubricating oil composition used as a lubricating oil for an automatic transmission.

[0002]

Lubricating oil for automatic transmissions used in automobiles, motor boats, agricultural machines, etc .: ATF (Automata)
tic Transmission Fluid)
The use of ashless dispersants is known. It is also known to use a metal-based detergent or the like for the purpose of increasing the friction coefficient (μ), or to use it in combination with these additives. For example, JP-A-3-39396, etc.

[0003]

However, since the ashless dispersant has a relatively higher effect of improving the friction coefficient than the metallic detergent, the ashless dispersant can be used to improve the friction coefficient more than the existing ATF. It is considered that the adsorption amount of the system dispersant is increased to improve the friction coefficient. However, if the addition amount of the ashless dispersant is increased, the balance between the system formed with other additives in the ATF is lost and the stability of the ATF becomes poor.

As described above, when an ashless dispersant, a friction modifier (FM agent) or a metal detergent is mixed in ATF,
The values of static friction coefficient (μs) and dynamic friction coefficient (μd) are not so high, and are not suitable for securing torque capacity, downsizing of clutch such as reduction of clutch diameter and number of clutches, and weight reduction. It was or,
If the friction coefficient is forcibly increased by increasing the addition amount of the ashless dispersant or the like, there is a problem that ATF with poor stability results.

On the other hand, some additives having a succinimide skeleton have an average molecular weight of 5500 or more. For example, the lubricating oil composition described in JP-A-6-240275 has an amine compound of 0.01 to 3.0% by weight, an overbased calcium phenate of 0.05 to 5.0% by weight, and a succinimide. Ashless dispersant 0.5 to 5.0% by weight, and B-shielding succinimide ashless dispersant 0.5 to 5.0
% By weight. This succinimide has a carbon number of 500 to 5000 (molecular weight of 7000 to 7).
0000) is used.

However, the dispersant has a molecular weight of 7,000.
~ 70,000 succinimide has a kinematic viscosity of 3 at 100 ° C.
When added to a base oil having a cSt or more, if these additives are added in an amount similar to that of the above-mentioned relatively low molecular weight dispersant, the viscosity of the entire ATF will increase. Therefore, the amount of the viscosity index improver (polymethacrylate) is reduced, but then the desired viscosity index cannot be achieved as the ATF.

If the viscosity index of ATF cannot be set high,
Viscosity changes greatly with temperature, resulting in high temperatures (for example, 10
If the kinematic viscosity at 0 ° C. is made uniform (usually about 7 cSt), the low temperature viscosity will increase. In this case, the hydraulic control of the transmission is the ATF having a high friction coefficient and a high viscosity index.
There is a disadvantage that it does not go smoothly compared to. The branch point of the viscosity index (VI) at which this problem occurs is around VI = 190 in the case of the high friction coefficient ATF of the present invention. That is, a viscosity index of 200 or more is preferable and 190
If it does not satisfy the above condition, a problem occurs when the coefficient of friction is high.

[0008]

Therefore, the inventor of the present invention has proposed a type peculiar to the ashless dispersant (see 8
It was possible to improve the adsorption amount by using a specific combination of these types, and eventually to improve the friction coefficient of ATF. The alkenyl succinimide used here as the ashless dispersant has a short-chain alkenyl group with an average molecular weight of 1000 to 1500 and a long-chain alkenyl group with an average molecular weight of 20.
It is necessary to blend those of 00 to 2500.

According to the present invention, since the metallic detergent is not contained, the adsorption of succinimide is not hindered, and the friction coefficient (μ) is improved. The addition amount of the friction modifier (FM agent: alkylamine) is 0.1 to 1.0% by weight, but if the addition amount is less than 0.1% by weight, μ ₀ / μ _d >.
1 and when the amount added is more than 1.0% by weight, the function of lowering the friction coefficient (μ) becomes large. In order to further improve the viscosity index, the use of a low-viscosity base oil improves, but it is practically problematic because it is volatile.

Alkenyl succinimides used as ashless dispersants in lubricating oil compositions include the following types: I) Monotype II) Bis type (two succinimide skeletons) III) B type (boron-introduced type) IV) Non-B type V) Long chain type (length of alkenyl chain is average molecular weight) In 2
000 to 2500) VI) Non-long chain type (alkenyl chain length is about 1000 to 1500 in terms of average molecular weight I) to VI) has the following chemical formula.

[0011]

Embedded image

There are the following eight types of alkenyl succinimide, including (a) B type bis type and (b) long chain monotype. (A) B-type bis type (b) Long-chain monotype (c) Non-long-chain non-B-type bis type (d) Non-B-type monotype (e) Long-chain bistype (f) B-type monotype (g) Long chain B type bis type (h) Long chain B type mono type

The eight combinations are as follows. Combination of 2 out of 8 types: ₈ C ₂ = 28 Combination of 3 out of 8 types: ₈ C ₃ = 56 However, it is known that combinations of 4 or more types have no effect. With this 28 + 56 = 84 combinations, it is possible to change the mixing ratio of the combined addition amount.

As an example of the combination by type, (a)
In the combination of B type bis type and (b) long chain monotype, there is a limit to the amount of adsorption between the case where only small molecule (a) is used and the case where only long chain molecule (large molecule) of (b) is used. , (A) 20 to 80 vol%, (b) 80 to 20 vo
When added to a base oil (mineral oil, synthetic oil) in a combination of 1%, preferably (a) 40 to 60 vol%, (b) 6
When 0 to 40 vol% was added, as shown in the test described later, the following effects were recognized as compared with the case where each was added alone. The amount of adsorption on iron increases. As a result, it has a high coefficient of friction (μ) when formulated as ATF.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION An adsorption amount measurement experiment was conducted under the following conditions. -Additive samples are PAO (polyalphaolefin, 10
Dissolve 5 wt% concentration in 0 ° C. 4 cSt) and collect about 200 cc in a beaker.・ Next, polish one side of SP material (φ20, thickness 2mm) and finish buffing to make it a mirror surface. This SP material was immersed in a beaker and heated at 120 ° C.-96 hrs. Adsorb under the conditions of. -Remove the adsorbed SP material sample and wash the surface with petroleum benzine.・ IR-RAS (Infrared high sensitivity reflection measurement method: Infra
red-Reflection Absorption
The peak intensity of the additive adsorbed on the surface of the SP material is measured by Spectroscopy).

The average molecular weight of the alkenyl group of the alkenyl succinimide is (a) B type bis type: average molecular weight 1000 to 1500
Degree (b) long chain monotype: average molecular weight 2000-2500
(C) Non-B type bis type: average molecular weight 1000-150
It was set to about 0. The molecular weight of the additive having an ultrahigh molecular weight succinimide skeleton used as a comparison is (x) average molecular weight 5500 to 7000 (y) average molecular weight 55000 to 70000.

FIG. 1 is a graph showing the results of measurement of the amount of adsorption. The horizontal axis shows (a) B type bis type: (b) long chain monotype = 50%: 50%, and (a) B type bis. Type 10
0% and (b) long chain monotype 100% are taken, and the vertical axis shows the peak intensity. As is clear from this graph, when alkenyl succinimide is used in a combination of (a) B-based bis type 50% and (b) long-chain monotype 50%, the above (a) and (b) are S more than when used alone
The amount of adsorption to the P material (iron) was obviously high.

FIG. 2 is a graph showing the test results of the chip-on-disk test, where the horizontal axis represents the peripheral speed (m / s) and the vertical axis represents the coefficient of friction (μ). As shown in this graph,
When (a) B type bis type 2.5% and (b) long chain monotype 2.5% are added in combination, respectively, (a), (b)
The coefficient of friction was greater than when 5% each was used alone.

The monotype and the bis type differ in structure, number of polar groups (C = 0, N), molecular weight, etc., and when added in combination, micelles (aggregates) are easily formed and high density per unit area is achieved. It is considered to be adsorbed on.

Adjust the ATF based on the results of this test,
SAE NO. The static friction coefficient (μs), the dynamic friction coefficient (μd), and μ ₀ / μd were measured in 2 tests.
The results are shown in Table 1, Table 2 and Table 3. (The addition amounts of other additives are the same.) In addition, Table 1 is a component table of Examples 1 to 9, and Table 2 is Comparative Examples 1 to 1.
No. 0 component table, Table 3 shows Comparative Examples 8 and 11-14 and Example 1
It is a component table of 0 to 15, and SAE NO. 2 is a table showing the results of the test in the 2 test (clutch friction test).

[0021]

[Table 1]

The following additives are added to the base oil at a maximum of 30% (addition of 30% or more has no effect commensurate with the cost of the additives). (Detergent-dispersing agent) Alkenyl succinimide: 1 to 10% If 1% or less, no effect can be expected, and if 10% or more, oxidative stability is poor and precipitation or precipitation occurs. (Viscosity index improver) Polymethacrylate: 4 to 20% No effect can be expected at 4% or less, and it is difficult to dissolve at 20% or more. (Antioxidant) Alkyldiphenylamine: 0.5 to 4% If 0.5% or less, no effect can be expected, and if 4% or more, oil is deteriorated. (Friction modifier) Alkylamine: 0.05 to 1% If 0.05% or less, no effect can be expected, and if 1% or more, oil is deteriorated. (Extreme pressure agent) SP compound (commercial item "Basolve 719", manufactured by Vanderbilt): 0.1-4% If 0.1% or less, no effect can be expected, and if 4% or more, toxicity is large and heat resistance Is bad.

The kinematic viscosity of the base oil is 3 to 5 cS at 100 ° C.
t. A combination of two or more kinds of mineral oil fractions or synthetic oils may be used. Although there is a method of using a low-viscosity base oil to increase the viscosity index, it cannot be used for a long time because it is volatile and has a low flash point. Further, the blending ratio of the additives is as described in the examples, but once the blending amount of one additive is determined, the blending amount of the other additives is also determined by the proportion, and the balance of the lubricant system is Can be taken.

(Example 1): Alkenyl succinimide, (a) B type bis type: (b) long chain monotype =
2.5 wt%: 2.5 wt% = 50 wt%: 50 wt%
Blended with. The first half of the proportional formula is the ratio to the base oil, and the second half is the ratio of the two alkenyl succinimides. The same applies hereinafter.

(Example 2): Alkenyl succinimide, (a) B type bis type: (b) long chain monotype =
3.0 wt%: 2.0 wt% = 60 wt%: 40 wt%
Blended with.

(Example 3): Alkenyl succinimide (a) B type bis type: (b) long chain monotype =
2.0 wt%: 3.0 wt% = 40 wt%: 60 wt%
Blended with.

(Example 4): Alkenyl succinimide (a) B type bis type: (b) long chain monotype =
3.5 wt%: 1.5 wt% = 70 wt%: 30 wt%
Blended with.

(Example 5): Alkenyl succinimide (a) B type bis type: (b) long chain monotype =
1.5 wt%: 3.5 wt% = 30 wt%: 70 wt%
Blended with.

(Example 6): Alkenyl succinimide, (a) B type bis type: (b) long chain monotype:
(C) Non-B type bis type = 2.5 wt%: 1.25 wt
%: 1.25 wt% = 50 wt%: 25 wt%: 25w
Blended at t%.

(Example 7) Alkenyl succinimide was used as (a) B type bis type: (b) long chain monotype =
2.5 wt%: 2.5 wt% = 50 wt%: 50 wt%
Blended with. The ratio of alkylamine to base oil is
It is 0.2 wt%.

(Example 8): Alkenyl succinimide (a) B type bis type: (b) long chain monotype =
2.5 wt%: 2.5 wt% = 50 wt%: 50 wt%
Blended with. The ratio of alkylamine to base oil is
It is 0.1 wt%.

(Example 9) Alkenyl succinimide was used as (a) B type bis type: (b) long chain monotype =
2.5 wt%: 2.5 wt% = 50 wt%: 50 wt%
Blended with. The ratio of alkylamine to base oil is
It is 1.0 wt%.

[0033]

[Table 2]

In the examples, the compounding range of polydimethylsiloxane is 10 ppm to 100 ppm. 10 ppm
In the following cases, improvement of friction coefficient cannot be expected and 100pp
If it is more than m, it cannot be dispersed.

In the examples, the friction coefficient and the viscosity index are improved because the polydimethylsiloxane makes the bis type and the mono type arranged uniformly, so that the adsorption on iron is dense and the adsorption amount is high. It seems to increase. Further, it is considered that the polydimethylsiloxane suppresses air bubbles in the oil generated when the ATF is mechanically stirred, and promotes dispersion of bis type and mono type and adsorption of metal. Especially high molecular weight (kinematic viscosity 50
Polydimethylsiloxane (00 to 20000 cSt) (25 ° C) and low molecular weight (kinematic viscosity 10 to 100 cSt)
(25 ° C) polydimethylsiloxane 4: 1 to 1: 4
It is considered that the above adsorption is promoted when mixed at a ratio of.

In the absence of polydimethylsiloxane, sufficient dispersion and adsorption cannot be realized. The defoaming effect is insufficient, and the ratio of non-contact parts increases due to oil film breakage, etc.
The improvement of the friction coefficient of is hindered. For the above reasons, A
It is considered to have a negative influence on improving the friction coefficient of TF.

(Comparative Example 1): Alkenyl succinimide was added to (a) B type bis type of 5.0 wt%, and (b).
Do not mix long chain monotype.

(Comparative Example 2): Alkenyl succinimide was blended with (b) 5.0 wt% of long-chain monotype, (a)
B type bis type is not mixed.

(Comparative Example 3): Alkenyl succinimide (a) B type bis type: (b) long chain monotype =
0.5 wt%: 4.5 wt% = 10 wt%: 90 wt%
Blended with.

(Comparative Example 4): Alkenyl succinimide (a) B type bis type: (b) long chain monotype =
4.5 wt%: 0.5 wt% = 90 wt%: 10 wt%
Blended with.

(Comparative Example 5): Alkenyl succinimide (a) B type bis type: (b) long chain monotype =
1.0 wt%: 4.0 wt% = 20 wt%: 80 wt%
Blended with.

(Comparative Example 6): Alkenyl succinimide was used as (a) B type bis type: (b) long chain monotype =
4.0 wt%: 1.0 wt% = 80 wt%: 20 wt%
Blended with.

(Comparative Example 7): Ultra high molecular weight alkenyl succinimide, (x) B type bis type: (y) long chain monotype = 2.5 wt%: 2.5 wt% = 50 wt%: 5
Blended with 0 wt%. The ratio of polymethacrylate to the base oil is 4.0 wt%.

(Comparative Example 8): Ultra high molecular weight alkenyl succinimide, (x) B type bis type: (y) long chain monotype = 2.5 wt%: 2.5 wt% = 50 wt%: 5
Blended with 0 wt%.

(Comparative Example 9) Alkenyl succinimide was added to (a) B type bis type: (b) long chain monotype =
2.5 wt%: 2.5 wt% = 50 wt%: 50 wt%
Blended with. The ratio of alkylamine to base oil is
It is 0.01 wt%.

[0046]

[Table 3]

When a high molecular weight polydimethylsiloxane and a low molecular weight polydimethylsiloxane are used in combination, the adsorption generated by the combination of succinimide monotype and bistype is further promoted, and the friction coefficient is improved. Conceivable.

It has been found that when ATF is formulated with a combination of succinimide monotype and bis type with the addition of a small amount of trilauryl trithiophosphate, the coefficient of friction is improved. This is considered to exert the effect of further complementing the effect of improving the friction coefficient by adsorption obtained by the combination of succinimide.

(Example 10): Ultra high molecular weight alkenyl succinimide (x) B type bis type: (y) long chain monotype = 2.5 wt%: 2.5 wt% = 50 wt%: 5
Blended with 0 wt%. Further, trilauryl trithiophosphate is blended in an amount of 0.01 wt% with respect to the base oil. As for polydimethylsiloxane, 25 ppm of low molecular weight and 25 ppm of high molecular weight are blended.

(Example 11): Ultra high molecular weight alkenyl succinimide (x) B type bis type: (y) long chain monotype = 2.5 wt%: 2.5 wt% = 50 wt%: 5
Blended with 0 wt%. Also, trilauryl trithiophosphate is blended in an amount of 0.01 wt% with respect to the base oil.

(Example 12) Alkenyl succinimide was used as (a) B-based bis type: (b) long-chain monotype =
2.5 wt%: 2.5 wt% = 50 wt%: 50 wt%
Blended with. The polydimethylsiloxane is blended with 25 ppm of low molecular weight and 25 ppm of high molecular weight.

(Example 13) Alkenyl succinimide was used as (a) B type bis type: (b) long chain monotype =
2.5 wt%: 2.5 wt% = 50 wt%: 50 wt%
Blended with. Also, trilauryl trithiophosphate,
Add 0.01 wt% to the base oil.

(Example 14) Alkenyl succinimide was used as (a) B type bis type: (b) long chain monotype =
2.5 wt%: 2.5 wt% = 50 wt%: 50 wt%
Blended with. The polydimethylsiloxane is blended with 25 ppm of low molecular weight and 25 ppm of high molecular weight.

(Example 15) Ultra high molecular weight alkenyl succinimide (x) B type bis type: (y) long chain mono type = 2.5 wt%: 2.5 wt% = 50 wt%: 50
Blended in wt%. The polydimethylsiloxane is blended with 25 ppm of low molecular weight and 25 ppm of high molecular weight.

(Comparative Example 10): Ultra high molecular weight alkenyl succinimide (x) 5.0 wt% of B type bis type was compounded, and (b) long chain monotype was not compounded. The polydimethylsiloxane is blended with 25 ppm of low molecular weight and 25 ppm of high molecular weight.

(Comparative Example 11): 5.0% by weight of (x) B-based bis type alkenyl succinimide was blended and (b) long chain monotype was not blended. Also, trilauryl trithiophosphate was added to the base oil at 0.01
wt% is added.

(Comparative Example 12): (a) B-based bis type of 5.0 wt% was blended with alkenyl succinimide,
(B) Long chain monotype is not mixed. The polydimethylsiloxane is blended with 25 ppm of low molecular weight and 25 ppm of high molecular weight.

(Comparative Example 13) Alkenyl succinimide was mixed in (a) B type bis type of 5.0 wt%, and (b)
Do not mix long chain monotype. Also, trilauryl trithiophosphate is blended in an amount of 0.01 wt% with respect to the base oil.

FIG. 3 is a graph showing the change of the static friction coefficient depending on the change of the blending amount of alkenyl succinimide in Tables 1 and 2, and FIG. 4 is the dynamic friction coefficient depending on the change of the blending amount (wt%) of alkenyl succinimide. It is a graph which shows the change of.

As is clear from FIGS. 3 and 4, it was found that the amount of alkenyl succinimide adsorbed affects the increase in ATF μ. , (B) 20 long chain monotypes
When blended in a ratio of from wt% to 80 wt%, preferably 3
When blended in a proportion of 0 wt% to 70 wt%, a high static friction coefficient (μs) and high dynamic friction coefficient (μd) can be obtained.

At this time, as described with reference to FIGS. 1 and 2, (a) B type bis type has an average molecular weight of 1000 to 15
00, (b) long chain monotype has an average molecular weight of 2000
It is about 2,500.

[0062]

As described in detail above, the present invention has the following effects. According to claim 1, two types of alkenyl succinimide of bis type and mono type are added to the base oil, and kinematic viscosity of polydimethylsiloxane is 10 to 100.
Low molecular weight cSt and kinematic viscosity 5000 to 20000 cS
Since the additive in which the high molecular weight substance of t is combined is blended, the adsorption amount is controlled, and the friction coefficient can be improved.

According to the second aspect of the present invention, since the base oil is blended with the additive which is a combination of two types of alkenyl succinimide of bis type and mono type and trilauryl thiophosphate, the static friction coefficient and the dynamic friction coefficient are improved. Can be made.

According to claim 3, the base oil has an alkenyl group having an average molecular weight of 1,000 to 1,500 and 2,000 to 25.
Since two kinds of alkenyl succinimide additives of No. 00 are mixed, the friction coefficient can be improved.

According to claim 4, the kinematic viscosity at 100 ° C. is 3
The average molecular weight of the alkenyl group is 10 in base oil of cSt or more
Since two kinds of alkenyl succinimide additives of 00 to 1500 and 2000 to 2500 are mixed, the viscosity index can be improved and the static friction coefficient and the dynamic friction coefficient can be improved.

[Brief description of drawings]

FIG. 1 is a graph showing a measurement result of an adsorption amount.

FIG. 2 is a graph showing the results of a chip-on-disk test.

[Fig. 3] Blend amount of alkenyl succinimide (% by weight)
Graph showing changes in static friction coefficient due to changes in

FIG. 4 Blending amount of alkenyl succinimide (% by weight)
Graph showing changes in dynamic friction coefficient due to changes in

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Claims (4)

[Claims] 1. A base oil containing the following additives, two alkenyl succinimides of bis type and mono type, a low molecular weight substance having a kinematic viscosity of 10 to 100 cSt and a high molecular weight substance having a kinematic viscosity of 5,000 to 20,000 cSt. A lubricating oil composition prepared by combining and 2. A lubricating oil composition prepared by combining a base oil with the following additives, two alkenyl succinimides of bis type and mono type, and trilauryl thiophosphate. 3. The following additives to the base oil, wherein the alkenyl group has an average molecular weight of 1000 to 1500 and 2.
A lubricating oil composition containing 000 to 2500 alkenyl succinimide. 4. A base oil having a kinematic viscosity at 100 ° C. of 3 cSt or more and the following additives, and the alkenyl group having an average molecular weight of 1000 to 1500:
A lubricating oil composition containing 000 to 2500 alkenyl succinimide.