JP5458718B2 - Lubricant composition and rolling bearing - Google Patents

Description

  The present invention relates to a lubricant composition and a rolling bearing.

  To date, rolling compositions used for various industrial machines, vehicles, electrical equipment, various motors, automobile parts, and the like have been filled with a grease composition in order to impart lubricity. In recent years, a reduction in torque has been required for the purpose of reducing the size and weight of devices and equipment, increasing the speed, and saving energy. Particularly in rolling bearings for vehicles, startability at low temperatures is also required.

  In order to reduce the torque, it is conceivable to enclose a grease composition having a low blending degree, but grease leakage tends to occur. Therefore, it has been proposed to use a lubricant composition that is made semi-solid by using a thickener and a gelling agent in combination (see, for example, Patent Documents 1 to 3).

JP 58-219297 A JP 2005-139398 A International Publication No. WO2006-051671

  The lubricant composition made into a semi-solid state using a gelling agent remains cured without being sheared when the bearing is not rotated, and when the bearing rotates, a shearing force acts to show fluidity. Therefore, leakage can be suppressed while maintaining lubricity. Moreover, since the amount of the thickener can be reduced, there is an effect that the amount of the base oil is relatively increased.

  However, since the lubricant composition made into a semi-solid state using a conventional gelling agent has a large blending ratio of the thickener, the fluidity when the shearing force is applied is not sufficient, and the time until it flows There is also a problem. Further, it cannot be said that the restoring property (flow-restoration reversibility) of returning to the original curing state or the fluid state in the process of repeating the cured state and the fluid state is sufficient.

  The present invention has been made in view of such circumstances, and further improves the fluidity and fluid-restoration reversibility of a lubricant composition made into a semi-solid state using a gelling agent and has a long lubrication life. The object is to provide a rolling bearing that is also low torque.

In order to achieve the above object, the present invention provides the following lubricant composition and rolling bearing.
(1) at least one amino acid-based gelling agent selected from N-2-ethylhexanoyl-L-glutamic acid dibutylamide, N-lauroyl-L-glutamic acid-α, γ-n-dibutyramide ;
At least one benzylidene sorbitol-based gelling agent selected from benzylidene sorbitol, ditrilidene sorbitol, and asymmetric dialkyl benzylidene sorbitol ,
Lubricant composition characterized in that the base oil is increased only by the gelling agent mixed at a mass ratio of amino acid gelling agent: benzylidene sorbitol gelling agent = 20-80%: 80-20%. object.
(2) In the inner space formed between the inner ring, the outer ring, a plurality of rolling elements movably arranged between the inner ring and the outer ring, and the inner ring and the outer ring, the above (1) A rolling bearing characterized by being filled with a lubricant composition .

Since the specific amino acid-based gelling agent and the specific benzylidene sorbitol-based gelling agent blended in the lubricant composition of the present invention have a chemical structure that easily forms hydrogen bonds, they are used in combination at a specific mixing ratio. By doing so, the base oil can be increased with a smaller blending amount. Further, the lubricant composition of the present invention has a large amount of change in viscosity due to the action of these gelling agents, can achieve low torque, and is excellent in flow-reversible recovery.

  In addition, in a rolling bearing filled with such a lubricant composition, there is no leakage of the lubricant, the lubrication life is excellent, and the torque is low.

It is a graph which shows the relationship between the kind of gelling agent obtained by Test 1, its compounding quantity, and the immiscible penetration. It is a graph which shows the relationship between the blending ratio of the amino acid type gelling agent and the benzylidene sorbitol type gelling agent obtained in Test 2 and the consistency recovery rate. 6 is a graph showing the change in the immiscibility consistency during three cycles of the lubricant composition of Example 1 obtained in Test 2. FIG.

Hereinafter, the present invention will be described in detail.
[Lubricant composition]
The lubricant composition of the present invention is obtained by increasing the base oil by using an amino acid gelling agent and a benzylidene sorbitol gelling agent in combination without using a thickener.

(Gelling agent)
As the amino acid-based gelling agents, because of its high synergistic effect with the benzylidene sorbitol gelling agent, N-2-ethyl-hexanoyl -L- glutamic acid dibutyl, N- lauroyl -L- glutamic acid-.alpha., gamma-n - use of dibutyl. These may be used in combination.

And a benzylidene sorbitol gelling agent, because of its high synergistic effect with the amino acid-based gelling agents, benzylidene sorbitol, di benzylidene sorbitol, dialkyl benzylidene sorbitol asymmetrical used. These may be used in combination.

  As shown in Test 1 to be described later, by using an amino acid gelling agent and a benzylidene sorbitol gelling agent in combination, the blending amount in the lubricant composition is greater than that when used alone due to a synergistic effect. Can be reduced. However, when the total amount of the amino acid-based gelling agent and the benzylidene sorbitol-based gelling agent exceeds 8% by mass, the initial consistency becomes too hard, and when applied to application places such as filling work on rolling bearings. The handleability of the is reduced. In addition, sufficient fluidity cannot be obtained even if shear is applied. On the other hand, if the amount is less than 2% by mass, the thickening action of the base oil is not sufficient, and it is too soft from the beginning and easily leaks from the application site such as a rolling bearing. Preferably it is 3-6 mass%.

The mixing ratio of the amino acid-based gelling agent and benzylidene sorbitol gelling agent is in a mass ratio, amino acid-based gelling agent: benzylidene sorbitol gelling = 20-80%: and 80 to 20%. When both the amino acid-based gelling agent and the benzylidene sorbitol-based gelling agent are less than 20% or more than 80%, the synergistic effect is lowered, and the degree of improvement in flow-restoration reversibility is lowered. Preferably, it is amino acid type gelling agent: benzylidene sorbitol type gelation = 40-70%: 60-30%.

(Base oil)
The base oil is not particularly limited as long as it is a lubricant that can dissolve the amino acid-based gelling agent and the benzylidene sorbitol-based gelling agent, and a mineral oil-based, synthetic oil-based or natural oil meter lubricant can be selected according to the purpose. The mineral oil-based lubricating oil is preferably refined by appropriately combining vacuum distillation, oil removal, solvent extraction, hydrocracking, solvent dewaxing, sulfuric acid washing, clay purification, hydrorefining, and the like. Examples of synthetic oils include hydrocarbon oils, aromatic oils, ester oils, and ether oils. Examples of natural oil-based lubricating oils include beef tallow, lard, soybean oil, rapeseed oil, rice bran oil, coconut oil, palm oil, palm kernel oil, and other oils and hydrides thereof. These base oils can be used alone or in admixture of two or more. Among these lubricating oils, those having polarity are preferable, and polyol ester oils and ether-based oils are more preferable.

Further, the kinematic viscosity of the base oil, in view of the lubricity and ^{low-torque, 10~400mm 2 / s (40 ℃} ) are ^{preferred, 20~250mm 2 / s (40 ℃} ) is more preferable.

(Additive)
In the lubricant composition of the present invention, various additives may be mixed as desired in order to further improve various performances. Additives include antioxidants such as amines, phenols, sulfurs, zinc dithiophosphates and zinc dithiocarbamates, rust preventions such as metal sulfonates, esters, amines, metal naphthenates, succinic acid derivatives, etc. Additives used for lubrication alone, such as agents, phosphorus-based, extreme pressure agents such as zinc dithiophosphate, organic molybdenum, oiliness improvers such as fatty acids and animal and vegetable oils, metal deactivators such as benzotriazole, Alternatively, two or more kinds can be mixed and used. In addition, the addition amount of these additives will not be specifically limited if it is a grade which does not impair the objective of this invention.

(Production method)
In the method for producing the lubricant composition of the present invention, first, an amino acid gelling agent and a benzylidene sorbitol gelling agent and a predetermined amount of additives are respectively added to the base oil, and the mixture is heated and stirred until the gelling agent is dissolved. To do. Next, the lubricant composition is poured into an aluminum bat that has been previously cooled with water, and the bat is cooled with cold water to obtain a gel. Then, the lubricant composition is obtained by applying the gel-like material to a three-roll mill.

[Rolling bearings]
The present invention also provides a rolling bearing encapsulating the above-described lubricant composition. However, the type and structure of the rolling bearing are not limited, and the bearing space is filled with the above-described lubricant composition.

  The rolling bearing of the present invention has a long lubricating life and low torque due to the lubricant composition.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

(Test 1)
Polyol ester oil (kinematic viscosity 33 mm ² / s, 40 ° C.), (A) N-2-ethylhexanoyl-L-glutamic acid dibutylamide only, (B) dibenzylidene sorbitol only, (C) N-2-ethyl Hexanoyl-L-glutamic acid dibutylamide and dibenzylidene sorbitol were added in equal amounts such that the blending amounts were 3% by mass, 4% by mass or 5% by mass, respectively, dissolved by heating and stirring, and then water-cooled in advance. It was poured into an aluminum bat, and the bat was cooled with cold water to be solidified in a gel form, and was subjected to a three-roll mill to obtain a lubricant composition.

  And the immiscible penetration of each lubricant composition was measured. The results are shown in FIG. 1, and the combined use of an amino acid gelling agent and a benzylidene sorbitol gelling agent can lower the immiscibility consistency even with the same blending amount.

(Test 2)
In the formulation shown in Table 1, the lubricant compositions of Examples 1-2 and Comparative Examples 1-3, and the total amount of 4% by mass, N-2-ethylhexanoyl-L-glutamic acid dibutylamide and dibenzylidene sorbitol What changed the mixture ratio was prepared. That is, N-2-ethylhexanoyl-L-glutamic acid dibutylamide as an amino acid-based gelling agent and dibenzylidene sorbitol as a benzylidene sorbitol-based gelling agent were added to 96 g of a polyol ester oil (kinematic viscosity 33 mm ² / s, 40 ° C.). A predetermined amount was added and dissolved by heating and stirring, and then poured into a water-cooled aluminum bat, and the bat was cooled with cold water to be solidified into a gel and subjected to a three-roll mill to obtain a lubricant composition.

Further, as Comparative Example 4, 8 g of lithium 12-hydroxystearate was added to 92 g of polyol ester oil (kinematic viscosity 33 mm ² / s, 40 ° C.), heated and dissolved, and then pre-cooled in an aluminum vat. After pouring, the bat was cooled with cold water to be solidified into a gel, and then applied to a three-roll mill to obtain a lubricant composition.

  And about each lubricant composition, the following (1) shear fluidity | liquidity test and (2) flow-restoration reversibility test were done.

(1) Shear fluidity test The initial immiscibility consistency of the lubricant composition was measured. Further, using a rotation-revolution stirrer, the mixture was stirred for 3 minutes at rotation 1370 r / min and revolution 1370 r / min, sheared, and then the immiscible penetration was measured.

  The results are also shown in Table 1. As the difference between the immiscible consistency before shearing and the immiscible consistency after shearing is larger, the viscosity change is larger and preferable. Moreover, if the immiscible penetration after shearing is 360 or more (consistency having no yield stress), it can be evaluated that there is fluidity due to shear. The lubricating compositions of Examples 1 and 2 have large viscosity changes and fluidity.

(2) A flow-restoration reversibility test was performed.
Using a rotation-revolution stirrer, the lubricant composition was stirred at rotation 1370 r / min and revolution 1370 r / min for 3 minutes, sheared, measured for immiscible penetration, and allowed to stand at 40 ° C. for 3 hours. After that, measuring the immiscible consistency again as one cycle is repeated three times. And each immiscible penetration was measured immediately after the first shearing and after 3 cycles, and the viscosity recovery rate was calculated from the following formula. The viscosity recovery rate is an index indicating the recovery performance when repeatedly subjected to shear. The higher the value, the lower the recoverability even when the shear is repeatedly applied. In addition, it has recovered to the initial consistency at 100%.

  The results are shown in Table 1 and FIG. 2, and are particularly good when the (N-2-ethylhexanoyl-L-glutamic acid dibutylamide: dibenzylidene sorbitol) ratio is in the range of 20-80%: 80-20%. The viscosity recovery rate is obtained.

  Moreover, although the change of the immiscible consistency between 3 cycles of the lubricant composition of Example 1 is shown in FIG. 3, it has shown favorable flow-reversible recoverability.

Claims (2)

At least one amino acid gelling agent selected from N-2-ethylhexanoyl-L-glutamic acid dibutylamide, N-lauroyl-L-glutamic acid-α, γ-n-dibutylamide ;
At least one benzylidene sorbitol-based gelling agent selected from benzylidene sorbitol, ditrilidene sorbitol, and asymmetric dialkyl benzylidene sorbitol ,
Lubricant composition characterized in that the base oil is increased only by the gelling agent mixed at a mass ratio of amino acid gelling agent: benzylidene sorbitol gelling agent = 20-80%: 80-20%. object. 2. The lubricant composition according to claim 1, wherein an inner ring, an outer ring, a plurality of rolling elements that are freely rollable between the inner ring and the outer ring, and an internal space formed between the inner ring and the outer ring are formed in the lubricant composition according to claim 1. A rolling bearing characterized by being filled with an object .

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