JP2015172165A - Lubricant composition for agricultural machinery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lubricant composition for agricultural machinery which has a high viscosity index and is excellent in low-temperature fluidity and shear stability and also high in flash point.SOLUTION: A lubricant composition for agricultural machinery contains a base oil having a 100°C kinematic viscosity of 3.5-5.5 mm/s, a viscosity index of 120 or greater and a %CP of 75 or higher and is blended with a polymethacrylate 1 of a mass average molecular wt. of 1×10to 3×10and a polymethacrylate 2 of a mass average molecular wt. of 4×10to 7×10.

Description

  The present invention relates to a lubricating oil composition, and more particularly to a lubricating oil composition used for agricultural machinery such as a tractor and a combine.

Agricultural machines such as tractors, rice planters, binders, and combines have many sliding parts such as hydraulic actuators, gears, clutches, and wet brakes, and it is common to lubricate them with one oil type. . For this reason, lubricating oils for agricultural machines are required to have various functions such as friction characteristics, wear resistance, oxidation stability, and rust prevention.
For example, the inclusion of a predetermined polysulfide compound has improved the extreme pressure property and the friction characteristic, and has been proposed as a common lubricating lubricant for tractors and construction machines (see Patent Document 1). In addition, friction is achieved by including a zinc dialkyldithiophosphate having a predetermined structure, one or more metal detergents selected from basic calcium sulfonate and basic calcium phenate, and a predetermined succinimide compound. Lubricating oil compositions for agricultural machinery that are excellent in properties, wear resistance and extreme pressure have been proposed (see Patent Documents 2 and 3).

JP 2001-311090 A JP 2009-144097 A JP 2009-144098 A

In recent years, in order to save fuel consumption of an internal combustion engine, the lubricating oil used has been reduced in viscosity in a low temperature region. Therefore, it is required to keep the viscosity index of the lubricating oil high. Moreover, since the lubricating oil used for agricultural machines, such as a tractor and a combine, receives a big shear over a long period of time by use environment, shear stability is also calculated | required. Furthermore, it is necessary to keep the flash point higher than the safety during use.
However, it is difficult for the lubricating oil composition for agricultural machinery described in Patent Documents 1 to 3 to satisfy all of the above-described problems.

  An object of the present invention is to provide a lubricating oil composition for agricultural machinery having a high viscosity index, excellent low-temperature fluidity and shear stability, and high flash point.

In order to solve the above problems, the present invention provides the following lubricating oil composition for agricultural machinery.
(1) A lubricating oil composition comprising a base oil having a kinematic viscosity at 100 ° C. of 3.5 mm ² / s or more and 5.5 mm ² / s or less, a viscosity index of 120 or more, and% CP of 75 or more. And a polymethacrylate 1 having a mass average molecular weight of 1 × 10 ⁵ or more and 2 × 10 ⁵ or less and a polymethacrylate 2 having a mass average molecular weight of 4 × 10 ⁴ or more and 7 × 10 ⁴ or less. A lubricating oil composition for agricultural machinery.
(2) The lubricating oil composition for agricultural machinery according to (1) above, wherein the composition satisfies at least one of the following (a) to (k): Composition.
(A) 40 ° C. kinematic viscosity of 33 mm ² / s or more and 37 mm ² / s or less (b) 100 ° C. kinematic viscosity of 7 mm ² / s or more and 9 mm ² / s or less (c) Viscosity index of 200 or more (d) Pour point (E) BF viscosity (−20 ° C.) is 2 Pa · s or less (f) BF viscosity (−40 ° C.) is 20 Pa · s or less (g) Decrease in kinematic viscosity at 100 ° C. in ultrasonic shear stability test The rate is 20% or less (3) In the lubricating oil composition for agricultural machinery according to the above (1) or (2), the kinematic viscosity at 100 ° C. is 10 mm ² / s to 12 mm ² / s, and the viscosity A lubricating oil composition for agricultural machinery, comprising a base oil having an index of 100 or more and 115 or less and a% CP of 65 or more and 85 or less.
(4) In the lubricating oil composition for agricultural machinery according to any one of (1) to (3) above, the mass average molecular weight is 1 × 10 ⁴ or more and 3.9 × 10 ⁴ or less. A lubricating oil composition for agricultural machinery, comprising polymethacrylate 3.
(5) In the lubricating oil composition for agricultural machinery according to any one of (1) to (4) above, a metal system having a base number by the hydrochloric acid method of 150 mgKOH / g or more and 180 mgKOH / g or less A lubricating oil composition for agricultural machinery, comprising a detergent.
(6) The lubricating oil composition for agricultural machinery according to (5) above, wherein the metal detergent is at least one of metal salicylate, metal phenate and metal sulfonate. Composition.
(7) The lubricating oil composition for agricultural machinery according to (6) above, wherein the metal detergent is an alkaline earth metal detergent.
(8) The lubricating oil composition for agricultural machinery according to (7) above, wherein the alkaline earth metal is Ca.

  ADVANTAGE OF THE INVENTION According to this invention, it can provide the lubricating oil composition for agricultural machines which is a high viscosity index | exponent, is excellent in low-temperature fluidity | liquidity and shear stability, and has a high flash point. The present invention is particularly suitable for tractors, combines and the like.

The lubricating oil composition for agricultural machinery of the present invention (hereinafter also referred to as “the present composition”) has a kinematic viscosity at 100 ° C. of 3.5 mm ² / s to 5.5 mm ² / s and a viscosity index of 120. Polymethacrylate 1 containing a base oil having a% CP of 75 or more and a weight average molecular weight of 1 × 10 ⁵ or more and 2 × 10 ⁵ or less, and a weight average molecular weight of 4 × 10 ⁴ or more and 6 × 10 ⁴ It is characterized by blending the following polymethacrylate 2. Details will be described below.

[Base oil]
The base oil used in the composition may be mineral oil or synthetic oil. Various conventionally known oils can be used as the mineral oil, and examples thereof include paraffin-based mineral oil, intermediate-based mineral oil, and naphthene-based mineral oil. Specifically, light neutral oil, intermediate neutral oil, heavy neutral oil, bright stock, etc. by solvent refining or hydrogen refining can be mentioned. As the synthetic oil, various conventionally known oils can be used. For example, poly α-olefin (including α-olefin copolymer), polybutene, polyol ester, dibasic acid ester, phosphate ester, Polyphenyl ether, alkylbenzene, alkylnaphthalene, polyoxyalkylene glycol, neopentyl glycol, silicone oil, trimethylolpropane, pentaerythritol, hindered ester, and the like can be used. These base oils can be used singly or arbitrarily in combination of two or more, and a mineral oil and a synthetic oil may be used in combination.

Here, the 100 ° C. kinematic viscosity of the above base oil is 3.5 mm ² / s or more and 5.5 mm ² / s or less, preferably 4 mm ² / s or more and 5 mm ² / s or less. If the 100 ° C. kinematic viscosity is less than 3.5 mm ² / s, the flash point will be lowered. On the other hand, when the 100 ° C. kinematic viscosity exceeds 5.5 mm ² / s, the pour point becomes high and the low temperature fluidity deteriorates.
The viscosity index of the above base oil is 120 or more, preferably 125 or more. When the viscosity index of the base oil is less than 120, the viscosity index when used as a composition is lowered.
The% CP of the base oil is 75 or more. When the% CP is less than 75, the viscosity index when the composition is used is lowered. In addition,% CP is calculated | required by ring analysis (ndM method).
The preferable content of the base oil is 50% by mass or more and 95% by mass or less based on the total amount of the composition. If the blending amount of the base oil is less than 50% by mass, the performance as a base oil may not be sufficiently imparted to the present composition. On the other hand, when the blending amount of the base oil exceeds 95% by mass, the functions of the additives described later may not be sufficiently exhibited.

In addition to the above-described base oil (also referred to as “base oil 1” for convenience), the composition further has a kinematic viscosity at 100 ° C. of 10 mm ² / s to 12 mm ² / s and a viscosity index of 100 or more. A base oil having 115 or less and% CP of 65 or more and 85 or less (also referred to as “base oil 2” for convenience) may be included.
By mixing and using base oil 2 with base oil 1, the thickness of the oil film can be increased, and wear resistance and fatigue life can be improved. It is also possible to increase the flash point. The blending ratio of the base oil 1 and the base oil 2 is preferably in the range of 0 to 0.5 in mass ratio “base oil 2 / base oil 1” from the viewpoint of the effect of the present invention.

[Polymethacrylate (PMA)]
The present composition is prepared by blending two types of polymethacrylate (hereinafter also referred to as “PMA”) with a base oil. Hereinafter, these two types of PMA are referred to as PMA1 and PMA2 for convenience.
PMA1 is a so-called high molecular weight PMA, and has a mass average molecular weight (hereinafter also referred to as “Mw”) of 1 × 10 ⁵ or more and 3 × 10 ⁵ or less, preferably 1 × 10 ⁵ or more and 2 × 10 ⁵ or less. It is.
Here, when Mw of PMA1 exceeds 3 × 10 ⁵ , shear stability is lowered. On the other hand, when the Mw of PMA1 is less than 1 × 10 ⁵ , the effect of improving the viscosity index is inferior. PMA2 has an Mw in the range of 4 × 10 ⁴ or more and 7 × 10 ⁴ or less, and is a polymethacrylate having a medium molecular weight, but mainly exhibits an effect of lowering the pour point. The preferable Mw of PMA2 is 4 × 10 ⁴ or more and 6 × 10 ⁴ or less. In the present composition, by using the above-described PMA1 and PMA2 in combination, it is possible to achieve both a high viscosity index and shear stability, and to lower the pour point.
The preferable amount of PMA1 is 1% by mass or more and 20% by mass or less based on the total amount of the composition, and the more preferable amount is 1% by mass or more and 10% by mass or less. The preferable amount of PMA2 is 0.1% by mass or more and 2% by mass or less based on the total amount of the composition, and the more preferable amount is 0.1% by mass or more and 1% by mass or less.
Moreover, the preferable compounding ratio (mass ratio, PMA1 / PMA2) of PMA1 and PMA2 is 0.5 or more and 200 or less, and a more preferable compounding ratio is 0.5 or more and 100 or less.
Here, when a low molecular weight polymethacrylate having Mw of 1 × 10 ⁴ or more and 3.9 × 10 ⁴ or less is blended as PMA3, shear stability is further improved. The preferable Mw of PMA3 is 2 × 10 ⁴ or more and 3.9 × 10 ⁴ or less.
In addition, Mw can be measured using size exclusion chromatography, for example. As a method using this technique, there is a Prominence GPC system manufactured by Shimadzu Corporation.

[Metal-based detergent]
In the present composition, it is preferable to add a metallic detergent to the base oil from the viewpoint of maintaining the cleanliness of the lubricating oil.
The metal detergent is preferably at least one of metal salicylate, metal phenate and metal sulfonate. As the metal, an alkaline earth metal is preferable, and Ca is more preferable. From the viewpoint of maintaining cleanliness, Ca salicylate is particularly preferable.
As the metallic detergent, in order to maintain the cleanliness of the lubricating oil, the base number by the hydrochloric acid method is preferably 100 mgKOH / g or more and 250 mgKOH / g or less, more preferably 150 mgKOH / g or more and 180 mgKOH / g or less. .
As a compounding quantity of a metal type detergent, it is preferable that they are 0.1 mass% or more and 10 mass% or less on the composition whole quantity basis, and it is more preferable that they are 0.1 mass% or more and 3 mass% or less. Moreover, in terms of metal amount, it is preferably 60 mass ppm or more and 6000 mass ppm or less, and more preferably 60 mass ppm or more and 2000 mass ppm or less. If the blending amount of the metal detergent is less than the above lower limit value, the effect of maintaining cleanliness may not be sufficient. On the other hand, even if the blending amount of the metal detergent exceeds the upper limit described above, it may be difficult to obtain an effect commensurate with the blending amount.

[This composition]
The lubricating oil composition for agricultural machinery of the present invention preferably satisfies at least one of the following (a) to (k).
(A) 40 ° C. kinematic viscosity of 33 mm ² / s or more and 37 mm ² / s or less (b) 100 ° C. kinematic viscosity of 7 mm ² / s or more and 9 mm ² / s or less (c) Viscosity index of 200 or more (d) Pour point (E) BF viscosity (−20 ° C.) is 2 Pa · s or less (f) BF viscosity (−40 ° C.) is 20 Pa · s or less (g) Decrease in kinematic viscosity at 100 ° C. in ultrasonic shear stability test 20% or less

When the 40 ° C. kinematic viscosity or 100 ° C. kinematic viscosity of the composition satisfies the above-described range, the fuel economy and the low temperature fluidity can be improved without deteriorating other performances.
When the viscosity index is 200 or more, the temperature dependence of the viscosity of the composition can be sufficiently suppressed. The viscosity index of the composition is more preferably 210 or more.
This composition becomes more excellent in low-temperature fluidity when the pour point, BF viscosity (−20 ° C.) and BF viscosity (−40 ° C.) satisfy the above (d), (e) and (f), respectively. .

  In the ultrasonic shear stability test according to JPI-5S-29-2006, this composition was subjected to an output voltage at which the rate of decrease in kinematic viscosity at 40 ° C. was 25% after irradiating 30 mL of standard oil with ultrasonic waves for 10 minutes. When the rate of decrease in kinematic viscosity at 100 ° C. when the sample is irradiated with ultrasonic waves at that voltage is 20% or less, the shear stability when used for a long period of time becomes superior. A more preferable reduction rate of 100 ° C. kinematic viscosity is 15% or less. In addition, in the case of the decreasing rate of 40 degreeC kinematic viscosity in the same test, 15% or less is preferable and it is more preferable that it is 10% or less.

[Various additives]
Various additives such as an extreme pressure agent, an oily agent, an antioxidant, a rust inhibitor, a corrosion inhibitor, and an antifoaming agent can be blended with the present composition as long as the effects of the invention are not impaired.
Examples of the extreme pressure agent include sulfur-based, phosphorus-based, and boron-based extreme pressure agents. Examples of sulfur-based extreme pressure agents include sulfurized olefins, sulfurized fats and oils, sulfurized esters, thiocarbonates, dithiocarbamates, polysulfides, and the like. Examples of the phosphorus-based extreme pressure agent include zinc dithiophosphate, phosphite, alkyl or aryl acid phosphate, amine salts thereof, trialkyl or triaryl phosphate, and the like.
A preferable blending amount of the extreme pressure agent is in the range of about 0.1% by mass or more and 5% by mass or less, more preferably in the range of 0.5% by mass or more and 3% by mass or less based on the total amount of the composition.

Examples of the oily agent include aliphatic monocarboxylic acids, polymerized fatty acids, hydroxy fatty acids, aliphatic monoalcohols, aliphatic monoamines, aliphatic monocarboxylic amides, partial esters of polyhydric alcohols and aliphatic monocarboxylic acids (sorbitan). And a partial ester thereof. These may be used individually by 1 type and may be used in combination of 2 or more type.
Although the compounding quantity of an oiliness agent is not specifically limited, It is preferable that it is the range of 0.01 mass% or more and 5 mass% or less on the basis of the composition whole quantity.

  Examples of the rust preventive include fatty acid, alkenyl succinic acid half ester, fatty acid soap, alkyl sulfonate, polyhydric alcohol fatty acid ester, fatty acid amide, oxidized paraffin, alkyl polyoxyethylene ether, and the like. Although the preferable compounding quantity of a rust preventive agent is not specifically limited, It is the range of 0.01 mass% or more and 3 mass% or less on the basis of the composition whole quantity.

Examples of the corrosion inhibitor include benzotriazole corrosion inhibitors, benzimidazole corrosion inhibitors, benzothiazole corrosion inhibitors, thiadiazole corrosion inhibitors, and the like. Although the preferable compounding quantity of a corrosion inhibitor is not specifically limited, It is the range of 0.01 mass% or more and 1 mass% or less on the basis of the composition whole quantity.
Examples of antifoaming agents include silicone compounds and ester compounds. Although the preferable compounding quantity of an antifoamer is not specifically limited, It is the range of 1 mass ppm or more and 5000 mass ppm or less on the composition whole quantity basis.

  The composition has a high viscosity index, excellent low-temperature fluidity, excellent shear stability, and a high flash point. Therefore, the lubricating oil composition of the present invention is particularly suitable for agricultural machinery such as tractors.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples. The properties and performance of the base oil and the lubricating oil composition (sample oil) in each example were determined by the following method.
(1) Kinematic viscosity at 40 ° C. and 100 ° C. Based on the method described in JIS K2283, the kinematic viscosity at 40 ° C. and 100 ° C. (unit: mm ² / s) was measured.
(2) Viscosity index The viscosity index was calculated based on the method described in JIS K2283.
(3)% CA,% CN,% CP
It was measured by ring analysis ndM method.
(4) BF viscosity (-20 ° C, -40 ° C)
It measured based on JPI-5S-26-85.
(5) Pour point Measured according to JIS K 2269.

(6) Content of calcium (Ca) and phosphorus (P) It was measured according to JPI-5S-38-92.
(7) Base number It measured based on JIS K2501. The base number was determined by the hydrochloric acid method and the perchloric acid method, respectively.
(8) Shear stability (ultrasonic shear stability test)
The test was conducted in accordance with JPI-5S-29-2006, and 30 mL of standard oil was irradiated with ultrasonic waves for 10 minutes, and then the output voltage at which the kinematic viscosity decrease rate at 40 ° C. was 25% was determined. The rate of decrease (%) in each kinematic viscosity was calculated from the 100 ° C. kinematic viscosity and the 40 ° C. kinematic viscosity before and after the test when irradiated with ultrasonic waves.

[Examples 1-4, Comparative Examples 1-4]
A lubricating oil composition (sample oil) shown in Table 2 was prepared using a base oil (see Table 1) and various additives. The evaluation results of each sample oil are shown in Table 2.

鉱油Ａ〜Ｆはいずれも鉱油であり、合成油ＡはＰＡＯ（ポリアルファオレフィン）である。ここで、鉱油Ａ、Ｂ、Ｃおよび合成油Ａが本発明の基油１に相当し、鉱油Ｄが本発明の基油２に相当する。

Mineral oils A to F are all mineral oils, and synthetic oil A is PAO (polyalphaolefin). Here, the mineral oils A, B and C and the synthetic oil A correspond to the base oil 1 of the present invention, and the mineral oil D corresponds to the base oil 2 of the present invention.

1) PMA-a: polymethacrylate (Mw = 1.7 × 10 ⁵ ) (PMA1)
2) PMA-b: polymethacrylate (Mw = 3.2 × 10 ⁴ ) (PMA3)
3) PMA-c: polymethacrylate (Mw = 5.5 × 10 ⁵ )
4) PMA-d: polymethacrylate (Mw = 5.0 × 10 ⁴ ) (PMA2)
5) OCP: Olefin copolymer (Mw = 2.8 × 10 ⁵ )
6) Additive package: Additive package for tractor oil 7) Metal detergent: Ca salicylate (hydrochloric acid method base number: 164 mgKOH / g)
8) Antifoaming agent: silicone

[Evaluation results]
As is clear from the results shown in Table 2, the sample oils of Examples 1 to 4 (the lubricating oil composition for agricultural machinery of the present invention) have a high viscosity index, excellent low-temperature fluidity, and shear stability. The flash point is also high. In particular, it is worthy of special mention that the rate of decrease in viscosity at 100 ° C. in the shear stability test is 15% or less. Therefore, it can be understood that the lubricating oil composition for agricultural machinery of the present invention is particularly suitable for tractors, combines and the like.
On the other hand, since the sample oils of Comparative Examples 1 to 4 lack any of the configurations of the present invention, they cannot satisfy all of the problems of the present invention. In particular, the rate of decrease in viscosity at 100 ° C. exceeds 15% in the shear stability test.

Claims (8)

A lubricating oil composition for agricultural machinery comprising a base oil having a kinematic viscosity at 100 ° C. of 3.5 mm ² / s or more and 5.5 mm ² / s or less, a viscosity index of 120 or more, and a% CP of 75 or more. And
Polymethacrylate 1 having a weight average molecular weight of 1 × 10 ⁵ or more and 3 × 10 ⁵ or less,
A lubricating oil composition for agricultural machinery, comprising a polymethacrylate 2 having a mass average molecular weight of 4 × 10 ⁴ or more and 7 × 10 ⁴ or less. In the lubricating oil composition for agricultural machines according to claim 1,
The lubricating composition for agricultural machinery, wherein the composition satisfies at least one of the following (a) to (k).
(A) 40 ° C. kinematic viscosity of 33 mm ² / s or more and 37 mm ² / s or less (b) 100 ° C. kinematic viscosity of 7 mm ² / s or more and 9 mm ² / s or less (c) Viscosity index of 200 or more (d) Pour point (E) BF viscosity (−20 ° C.) is 2 Pa · s or less (f) BF viscosity (−40 ° C.) is 20 Pa · s or less (g) Decrease in kinematic viscosity at 100 ° C. in ultrasonic shear stability test 20% or less In the lubricating oil composition for agricultural machines according to claim 1 or 2,
And a base oil having a kinematic viscosity at 100 ° C. of 10 mm ² / s or more and 12 or less, a viscosity index of 100 or more and 115 or less, and a% CP of 65 or more and 85 or less. Composition. In the lubricating oil composition for agricultural machines according to any one of claims 1 to 3,
Further, agricultural machinery lubricating oil composition characterized in that the mass average molecular weight is blended with polymethacrylate 3 is 3.9 × 10 ⁴ or less 1 × 10 ⁴ or more. In the lubricating oil composition for agricultural machines according to any one of claims 1 to 4,
Further, a lubricating oil composition for agricultural machinery, comprising a metallic detergent having a base number by the hydrochloric acid method of 150 mgKOH / g or more and 180 mgKOH / g or less. In the lubricating oil composition for agricultural machines according to claim 5,
A lubricating oil composition for agricultural machinery, wherein the metal-based detergent is at least one of metal salicylate, metal phenate, and metal sulfonate. In the lubricating oil composition for agricultural machines according to claim 6,
The lubricating oil composition for agricultural machinery, wherein the metal detergent is an alkaline earth metal detergent. The lubricating oil composition for agricultural machinery according to claim 7,
A lubricating oil composition for agricultural machinery, wherein the alkaline earth metal is Ca.