JP5691877B2 - Lubricant composition and rolling bearing - Google Patents

Description

  The present invention relates to a lubricant composition containing a gelling agent and a rolling bearing in which the lubricant composition is enclosed.

  Although the lubricant composition is applied to the rotation support part of various apparatuses, what provided the retainability in the application location by containing a gelatinizer is known. For example, Patent Document 1 describes a grease composition increased by using a grease thickener in combination with a gelling agent capable of solidifying an organic liquid in a very small amount. In the grease composition of Patent Document 1, fluidity due to shearing and heat is improved by using a thickener and a gelling agent in combination, and the grease is prevented from flowing out because it is re-cured when the shearing and heat are removed. It has an effect that can be done. In addition, since the amount of thickener added can be reduced by the amount used in combination with the gelling agent, heat generation caused by stirring is suppressed and thermal deterioration of the lubricant is prevented. Torque has the effect of extending the life.

  Patent Document 2 describes a semi-solid lubricant composition containing a liquid crystal compound and a gelling agent as a lubricant composition useful for lubrication of precision devices such as computer HDDs and mobile phones. Yes. The lubricant composition of Patent Document 2 controls fluidity under static conditions, and easily flows by shearing under dynamic conditions (for example, a sliding portion) and contributes to lubrication.

JP 58-219297 A JP 2005-139398 A

  However, the lubricant composition containing the conventional gelling agent is softened due to the formation of an aggregate of the gelling agent in a high-temperature environment, and when shearing force is applied thereto, it flows into an oil but stops shearing. Sometimes it becomes difficult to re-form the network (network structure) by the gelling agent.

  Therefore, the present invention provides a lubricant composition in which even when used in a high-temperature environment, it easily becomes oily when shearing force is applied, and in a state where shearing is not applied, the network formed by the gelling agent is rapidly re-formed to become a gel. It is an object of the present invention to provide a rolling bearing having a long life and low torque and excellent seizure resistance.

In order to solve the above problems, the present invention provides the following lubricant composition and rolling bearing .
(1) A base oil, containing at least one gelling agent selected from an amino acid gelling agent and a benzylidene sorbitol derivative, and inorganic particles having a BET specific surface area of 300 m ² / g or more. A lubricant composition.
(2) A rolling bearing characterized in that a plurality of rolling elements are rotatably held between an inner ring and an outer ring, and the lubricant composition described in (1) above is enclosed .

  The lubricant composition of the present invention contains a gelling agent comprising an amino acid gelling agent or a benzylidene sorbitol derivative, so that it easily becomes oily when shearing force is applied, and in a state where shearing is not applied, the gelling agent Since hydrogen bonding force is easily generated between them, the network formed by the gelling agent is rapidly re-formed to become a gel.

In addition, since inorganic particles having a specific specific surface area are interposed between the gelling agents, aggregation of the gelling agents in a high temperature environment is suppressed. And even if it flows into oily by applying a shearing force, since the gelling agent is not aggregated, a network of gelling agents is quickly formed, and the viscosity recoverability does not deteriorate.

  In this way, even in a high temperature environment, the viscosity recovery is excellent, and a good lubrication state can be maintained for a long time.

  Therefore, the rolling bearing of the present invention in which the lubricant composition of the present invention is encapsulated has low torque, excellent seizure resistance, and a long life.

It is sectional drawing which shows an example of the rolling bearing of this invention. It is a graph which shows the relationship between the BET specific surface area of an inorganic type particle | grain, and a viscosity recovery factor. It is a graph which shows the relationship between the BET specific surface area of an inorganic type particle | grain, and a relative baking lifetime.

  Hereinafter, the present invention will be described in detail.

[Gelling agent]
In the lubricant composition of the present invention, at least one selected from an amino acid gelling agent and a benzylidene sorbitol derivative is used as the gelling agent. Preferably, both an amino acid gelling agent and a benzylidene sorbitol derivative are used in combination. Since these gelling agents have a chemical structure in which hydrogen bonding is likely to occur between the gelling agents, a network formed by the gelling agents is not easily formed, and can be gelled in a small amount. Specifically, the content of the gelling agent can be 2 to 8% by mass of the total amount of the lubricant composition, and more preferably 3 to 6% by mass. When the content of the gelling agent is less than 2% by mass, the gelling agent is too soft from the beginning and easily leaks from the application site. When it exceeds 8% by mass, the initial consistency becomes too hard and the handling property is deteriorated, and even if a shearing force is applied, it does not flow into oil and the lubricity is also deteriorated.

  Moreover, when using together an amino acid type gelling agent and a benzylidene sorbitol derivative, it is preferable that a compounding ratio shall be an amino acid type gelling agent: benzylidene sorbitol derivative = 20-80: 80-20 (mass ratio), 40-60 : 60 to 40 (mass ratio) is more preferable. When it deviates from said compounding ratio, the synergistic effect by using together will become low, and the improvement degree of a viscosity recovery property will fall.

  As the amino acid gelling agent, for example, N-2-ethylhexanoyl-L-glutamic acid dibutylamide and N-lauroyl-L-glutamic acid-α, γ-n-dibutylamide are suitable.

  As the gelling agent comprising a benzylidene sorbitol derivative, for example, dibenzylidene sorbitol, ditrilidene sorbitol and asymmetric dialkylbenzylidene sorbitol are suitable.

[Inorganic particles]
In the present invention, inorganic particles are blended in order to suppress aggregation of the gelling agent at a high temperature. Inorganic particles, in order to more effectively suppress the aggregation of the gelling agent state, and are 300 meters ² / g or more in BET specific surface area, it is favorable preferable is 500 meters ² / g or more. Accordingly, the inorganic particles are not limited as long as they have such a BET specific surface area. For example, carbon black such as ketjen black, alumina, silica, zeolite, and the like are preferable, and ketjen black and zeolite are particularly preferable. Is preferred. Two or more inorganic particles may be used in combination.

  Moreover, 0.5-5 mass% of the amount of lubricant composition is preferable, and, as for content of an inorganic type particle | grain, 1-3 mass% is more preferable. When the content of the inorganic particles is less than 0.5% by mass, the effect of suppressing the aggregation of the gelling agent at a high temperature cannot be sufficiently obtained. When it exceeds 5% by mass, the initial consistency becomes too hard and the handling property is deteriorated, and even if a shearing force is applied, it does not flow into an oil and the lubricity is also deteriorated.

[Base oil]
The base oil constituting the lubricant composition is not particularly limited, and any of the oils (mineral oil-based, synthetic oil-based or natural oil-based lubricants) used as the base oil of ordinary lubricant compositions. Also good. Specifically, mineral oil base oils are those obtained by refining mineral oil by appropriately combining vacuum distillation, oil removal, solvent extraction, hydrocracking, solvent dewaxing, sulfuric acid washing, clay refining, hydrorefining, etc. Can be used. As the synthetic base oil, hydrocarbon oil, aromatic oil, ester oil, ether oil and the like can be used. As the natural oil-based base oil, beef tallow, lard, soybean oil, rapeseed oil, rice bran oil, coconut oil, palm oil, palm kernel oil and other oil-based oils, or hydrides thereof can be used.

  Various additives may be mixed in the lubricant composition for the purpose of improving 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. Agents, extreme pressure agents such as phosphorus-based, zinc dithiophosphate and organic molybdenum, oiliness improvers such as fatty acids and animal and vegetable oils, metal deactivators such as benzotriazole, and the like. These additives can be used alone or in admixture of two or more. These additives can be added in amounts that do not impair the object of the present invention.

〔Production method〕
In order to produce a lubricant composition, for example, a predetermined amount of a gelling agent and inorganic particles are blended in a base oil to which an additive is added as necessary, and the mixture is heated and stirred so that the gelling agent is dissolved. A liquid product is obtained. This liquid material is poured into a metal vat that has been previously cooled with water, and cooled with running water to obtain a gel-like material. And a lubricant composition is obtained by knead | mixing this gel-like thing with a 3 roll mill.

  The lubricant composition of the present invention can be applied to the rotation support portion of various devices. For example, it can be enclosed in a rolling bearing, a linear guide device, a ball screw, etc., and the high temperature durability can be improved. In addition, since it becomes oily even with extremely weak shear, low torque can be realized, and torque can be stabilized at an early stage.

  For example, FIG. 1 is a cross-sectional view showing a ball bearing 1 which is an example of a rolling bearing according to the present invention, and a plurality of balls 13 are held between an inner ring 10 and an outer ring 11 by a cage 12 so as to be able to roll. Further, the bearing space S formed by the inner ring 10, the outer ring 11 and the balls 13 is filled with the above-described lubricant composition (not shown) and sealed with seals 14 and 14.

  The present invention will be further described below with reference to examples and comparative examples.

[Test 1]
Example 1
Dibenzylidenesorbitol is blended with 94 g of a polyol ester having a kinematic viscosity at 40 ° C. of 33 mm ² / s, ² g of dibenzylidene sorbitol, 2 g of N-2-ethylhexanoyl-L-glutamic acid dibutylamide, and 2 g of ketjen black. And N-2-ethylhexanoyl-L-glutamic acid dibutylamide was heated and stirred until completely dissolved to obtain a liquid material comprising the lubricant composition. This liquid material was poured into an aluminum bat that had been previously cooled with water, and the bat was cooled with running water to obtain a gel-like material. And the sample of Example 1 was obtained by applying the gel-like material to a three-roll mill. In addition, the initial immiscibility penetration of the sample was measured.

(Examples 2 to 4 and Comparative Example 1.2)
Samples of Examples 2 to 4 and Comparative Examples 1 and 2 were obtained in the same manner as in Example 1 using the base oil, gelling agent and inorganic particles shown in Table 1. Moreover, the initial immiscible penetration of each sample was measured.

The following durability test was performed on the samples of Examples 1 to 4 and Comparative Examples 1 and 2. The results are also shown in Table 1.
(1) High temperature standing test 10 g of each sample was put in a stainless steel petri dish, left in a thermostat heated to 150 ° C. for 100 hours and then taken out, and after cooling, the immiscible penetration was measured. And stability at high temperature was evaluated by comparing with the initial immiscibility penetration. It can be said that the smaller the difference from the initial immiscibility, the better the high-temperature stability.
(2) Flow-recovery reversibility test The immiscibility (high temperature initial immiscibility) of the sample after the high temperature storage test was measured. Moreover, a sample is put into a rotation-revolution stirrer, and a shear force is applied under conditions of rotation 1370 r / min, revolution 1370 r / min, 3 minutes, and an immiscible consistency (immiscible consistency immediately after shearing) is obtained. It was measured. In addition, the sample after application of shear was allowed to stand at 40 ° C. for 3 hours, and the immiscible penetration (immiscible penetration after standing) was measured. And the viscosity recovery rate was computed from the following formula. It can be said that the higher the viscosity recovery rate, the better the flow-restoration reversibility.

  FIG. 2 is a graph showing the relationship between the BET specific surface area and the viscosity recovery rate of the inorganic particles based on the results of Examples 1 to 4 and Comparative Examples 1 and 2.

From the above results, it can be seen that the stability at high temperature and the viscosity recovery rate are increased by blending inorganic particles having a BET specific surface area of 300 m ² / g or more together with the gelling agent.

[Test 2]
(Examples 5-8 and Comparative Examples 3-5)
Samples of Examples 5 to 8 and Comparative Examples 3 to 5 were obtained in the same manner as in Test 1 using the base oil, gelling agent or thickener and inorganic particles shown in Table 2.

The following bearing tests were performed on the samples of Examples 5 to 8 and Comparative Examples 3 to 5. The results are also shown in Table 2.
(3) Bearing Torque Test A sample bearing was sealed in a deep groove ball bearing “6305” (inner diameter 25 mm, outer diameter 62 mm, width 17 mm, non-contact rubber seal) manufactured by NSK Ltd. to produce a test bearing. Then, the test bearing was rotated at 3000 min-1 at an axial load of 98 N, a radial load of 29.4 N, and room temperature, and an average torque value between 1200 seconds and 1800 seconds after the start of rotation was obtained. The results are shown as relative values where the average torque value of Comparative Example 3 is 1.
(4) Bearing seizure test A sample bearing was sealed in a deep groove ball bearing “6305” (inner diameter 25 mm, outer diameter 62 mm, width 17 mm, non-contact rubber seal) manufactured by NSK Ltd. to produce a test bearing. Then, the test bearing was rotated at 5000 min −1 at an axial load of 98 N, a radial load of 98 N, and an ambient temperature of 140 ° C., and the time until seizure (baking life) was determined. The results are shown as relative values with the baking life of Comparative Example 3 as 1.

  3 is a graph showing the relationship between the BET specific surface area of the inorganic particles and the relative bake life based on the results of Examples 5 to 8 and Comparative Examples 3 to 5. FIG.

From the above results, by encapsulating a lubricant composition containing inorganic particles having a BET specific surface area of 300 m ² / g or more together with a gelling agent, a rolling bearing having a low torque, excellent seizure resistance and a long life can be obtained. It turns out that it is obtained.

DESCRIPTION OF SYMBOLS 1 Ball bearing 10 Inner ring 11 Outer ring 12 Cage 13 Ball 14 Seal

Claims (2)

A lubricant comprising: a base oil; at least one gelling agent selected from an amino acid gelling agent and a benzylidene sorbitol derivative; and inorganic particles having a BET specific surface area of 300 m ² / g or more. Composition. A rolling bearing characterized in that a plurality of rolling elements are rotatably held between an inner ring and an outer ring, and the lubricant composition according to claim 1 is enclosed .

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