JP5347454B2 - Lubricant composition and rolling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lubricant composition which changes easily from a gel-like state to an oil-like state by imparting a shearing force to thereby flow and besides, when stopping the impartation of the shearing force, which recovers the viscosity quickly and has a gel-like state, and to provide a rolling device having excellent lubrication performance and a long life. <P>SOLUTION: This rolling device of a deep-groove ball bearing is provided with; an inner ring 1 having on an outer peripheral surface an orbit surface 1a, an outer ring 2 having on an inner peripheral surface an orbit surface 2a opposite to the orbit surface 1a, a plurality of rollers 3 arranged rolling-freely between the both orbit surfaces 1a, 2a; a ball bearing cage 4 holding a plurality of rollers 3 between the inner ring 1 and the outer ring 2; and sealing devices 5, 5 like a seal covering the opening for the clearance between the inner ring 1 and the outer ring 2. Additionally, the lubricant composition G to perform the lubrication for the deep-groove ball bearing is included in an air space part which is formed between the inner ring 1 and the outer ring 2 and is arranged with the rollers 3. So, a base oil for this lubricant composition G is a lubricating oil having a relative dielectric constant at 1 kHz frequency of from not less than 3 to not more than 50, and a gelling agent is a benzylidene sorbitol derivative. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a lubricant composition. The present invention also relates to a rolling device such as a rolling bearing, a ball screw, a linear guide device, and a linear motion bearing.

  The benzylidene sorbitol derivative is used as a gelling agent (thickening agent) in grease, but it can be gelled in a small amount as compared with a general gelling agent. For example, NLGI No. The amount of the gelling agent required to obtain a hardness of 2 (concentration 265 to 295) is 10 to 30% by mass for a general gelling agent, whereas 2 to 5 for a benzylidene sorbitol derivative. % By mass.

Grease using a benzylidene sorbitol derivative as a gelling agent has a very small amount of gelling agent used, so when shearing force is applied, it easily changes from a gel to an oil (concentration of 380 or more) and flows. Tend. A general grease does not change so much even if shearing force is applied. In the case of a grease using a soap-type thickener as a gelling agent, the change in consistency is about 10 to 40. In the case of grease using a thickener, there is almost no change.
JP 58-219297 A JP 2005-139398 A

However, a grease using a benzylidene sorbitol derivative as a gelling agent has a smaller amount of gelling agent used and a large change in viscosity due to the application of shearing force compared to general greases. However, there is a problem that the viscosity does not immediately recover and it takes time to return to a normal gel state to which no shear force is applied.
Therefore, the present invention solves the problems of the prior art as described above, and easily changes from gel to oil by flowing shear force and flows, and when the shearing force is stopped, the viscosity is quickly recovered. It is an object of the present invention to provide a lubricant composition that becomes a gel. Another object is to provide a long-life rolling device having excellent lubrication performance.

In order to solve the above problems, the present invention has the following configuration. That is, the lubricant composition according to the present invention, base oil and the lubricant composition comprising a gelling agent, an ester oil or glycol oil dielectric constant at a frequency of 1kHz is 3 or more and 50 or less said base oil The gelling agent is dibenzylidene sorbitol , the content of the gelling agent in the lubricant composition is 2% by mass or more and 10% by mass or less, and the shearing force measured after applying the shearing force is measured. Measure the mixing penetration, the immiscible penetration measured before applying the shearing force, and the application of the shearing force after applying the shearing force and let stand at 40 ° C. for 1 hour. The viscosity recovery rate calculated using the following formula is 80% or more from the immiscible penetration after standing, and the immiscibility penetration after applying the shearing force is 380 or more .
Viscosity recovery rate (%) = ([immiscible consistency after applying shear force] − [immiscible consistency after leaving]] / ([immiscible consistency after applying shear force] − [before applying shear force) Immiscible consistency])
In such a lubricant composition according to the present invention, the base oil is a diester oil or monool glycol oil having a relative dielectric constant of 3 or more and 50 or less at a frequency of 1 kHz, and the gelation in the lubricant composition. The content of the agent may be 4% by mass or more and 5% by mass or less. Moreover, the application of the shearing force can be performed using a rotation-revolution stirrer.

  The rolling device according to the present invention includes an inner member having a raceway surface on an outer surface, and an outer member disposed on the outer side of the inner member having a raceway surface facing the raceway surface of the inner member. In the rolling device, comprising: a member, a plurality of rolling elements that are arranged to freely roll between the both raceway surfaces, and a lubricant that performs lubrication between the raceway surfaces and the rolling elements. Is a lubricant composition as described above.

  The present invention can be applied to various rolling devices. For example, a rolling bearing, a ball screw, a linear guide device, a linear motion bearing, and the like. In the present invention, the inner member means an inner ring when the rolling device is a rolling bearing, a screw shaft when the ball screw is also used, a guide rail when the linear guide device is used, and a linear bearing device. Each axis means. The outer member is the outer ring when the rolling device is a rolling bearing, the nut when it is a ball screw, the slider when it is a linear guide device, and the outer cylinder when it is also a linear bearing. Each means.

  The lubricant composition of the present invention easily changes from a gel state to an oily state due to the application of a shearing force and flows, and when the application of the shearing force is stopped, the viscosity quickly recovers and becomes a gel state. Is excellent. The rolling device of the present invention has excellent lubrication performance and a long life.

DESCRIPTION OF EMBODIMENTS Embodiments of a lubricant composition and a rolling device according to the present invention will be described in detail with reference to the drawings.
FIG. 1 is a longitudinal sectional view showing a structure of a deep groove ball bearing which is an embodiment of a rolling device according to the present invention. This deep groove ball bearing has an inner ring 1 having a raceway surface 1a on the outer peripheral surface, an outer ring 2 having a raceway surface 2a facing the raceway surface 1a on the inner peripheral surface, and a raceway between the raceway surfaces 1a and 2a. A plurality of rolling elements (balls) 3, a cage 4 that holds the plurality of rolling elements 3 between the inner ring 1 and the outer ring 2, and a seal that covers the opening of the gap between the inner ring 1 and the outer ring 2 Sealing devices 5 and 5. Note that the cage 4 and the sealing device 5 may not be provided.

  A grease-like lubricant composition G that lubricates between the raceway surfaces 1a and 2a and the rolling element 3 is disposed in a gap formed between the inner ring 1 and the outer ring 2 and provided with the rolling element 3 therein. ing. The base oil of the lubricant composition G is a lubricant having a relative dielectric constant of 3 to 50 at a frequency of 1 kHz, and the gelling agent is a benzylidene sorbitol derivative. The benzylidene sorbitol derivative is preferably dibenzylidene sorbitol, ditrilidene sorbitol, or a mixture of both.

Hereinafter, the lubricant composition G will be described in detail. As described above, a lubricant composition using a benzylidene sorbitol derivative as a gelling agent has a smaller amount of gelling agent used and a large change in viscosity due to the application of shearing force compared to general grease. Even if the application is stopped, the viscosity does not recover immediately, and there is a problem that it takes time to return to a normal gel state where no shear force is applied.
In order to improve the recovery speed of the viscosity, it is necessary to quickly return the three-dimensional network structure of the gelling agent destroyed by the shearing force to the state before applying the shearing force. The ease of forming a three-dimensional network structure in the base oil of the gelling agent is thought to be due to the affinity between the base oil and the gelling agent.

  If the affinity between the two is poor, the gelling agent cannot be sufficiently dispersed in the base oil and becomes a highly agglomerated state, so that the three-dimensional network structure of the gelling agent cannot be formed. On the other hand, if the affinity between the two is good, the base oil and the gelling agent can be mixed appropriately, and therefore a three-dimensional network structure of the gelling agent is easily formed in the base oil. However, if the affinity between the two is too high, the gelling agent in the base oil will be in a highly dispersed state, so that the three-dimensional network structure of the gelling agent necessary for gelation will not be formed. It is not considered to be.

  As described above, the base oil and the gelling agent have an optimum affinity for easily forming a three-dimensional network structure. That is, there exists a base oil having an optimum affinity that is easy to form a three-dimensional network structure for the gelling agent. If a base oil that easily forms a three-dimensional network structure is selected for the gelling agent, even if the three-dimensional network structure of the gelling agent is destroyed due to the application of shearing force, gelation occurs when the application of shearing force is stopped. It is considered that the three-dimensional network structure of the agent is rapidly reformed to become a gel. That is, the viscosity recovery speed can be improved.

However, using a base oil that easily forms a three-dimensional network structure of the gelling agent, that is, a base oil that has a high affinity with the gelling agent has the disadvantage that viscosity change due to the application of shearing force hardly occurs (that is, it does not flow easily) This may need to be taken into account.
The present inventors have found that the affinity between the base oil and the gelling agent is related to the chemical structure (polarity) of both, and the closer the chemical structure of both, the better the affinity. Thought. Then, it was considered that a base oil having an optimum affinity that easily forms a three-dimensional network structure for the gelling agent can be selected by using a relative dielectric constant having a correlation with the magnitude of polarity as an index. As a result, it was found that the lubricant composition using a lubricating oil having a high dielectric constant as the base oil has a lower consistency, that is, a three-dimensional network structure tends to be stronger.

A lubricant composition using a lubricating oil having a relative dielectric constant of 3 or more and 50 or less at a frequency of 1 kHz as a base oil easily changes from a gel state to an oily state due to the application of a shearing force, and has a shearing force. It was found that when the application was stopped, the viscosity quickly recovered to become a gel (that is, the viscosity recovery rate was fast). A lubricant composition using a lubricating oil having a relative dielectric constant of less than 3 and more than 50 as a base oil at a frequency of 1 kHz has an insufficient viscosity recovery rate.
Since such a lubricant composition G has excellent lubrication performance, the deep groove ball bearing of this embodiment has a long life.

Below, each component which comprises the lubricant composition G is demonstrated in detail.
[About gelling agent]
As the benzylidene sorbitol derivative, an asymmetric dialkylbenzylidene sorbitol is suitable in addition to dibenzylidene sorbitol and ditrilidene sorbitol. These may be used alone or in combination of two or more.

  The content of the gelling agent in the lubricant composition G is preferably 2% by mass or more and 10% by mass or less. If the amount is less than 2% by mass, the lubricant composition G is too soft even in a state where no shear force is applied, and therefore the lubricant composition G is likely to leak from a rolling device such as a deep groove ball bearing. On the other hand, if it exceeds 10% by mass, the lubricant composition G in a state in which no shear force is applied is too hard, and handling becomes worse. Moreover, even if a shear force is applied, it is difficult to change from a gel to an oil, so that it may not flow.

[About base oil]
The type of base oil is not particularly limited as long as it is a lubricating oil having a relative dielectric constant of 3 to 50 at a frequency of 1 kHz, but ester oil, glycol oil, and the like are preferable. Examples of ester oils include aromatic tribasic acids, aromatic ester oils obtained by reaction of aromatic tetrabasic acids and branched alcohols, and polyol esters obtained by reaction of monobasic acids and polyhydric alcohols. Oil.

Examples of the aromatic ester oil include trimellitic acid ester oils such as toruoctyl trimellitate and tridecyl trimellitate, trimesic acid ester oil, and pyromellitic acid ester oils such as tetraoctyl pyromellitate.
Examples of the polyol ester oil include ester oils obtained by the reaction of the following monobasic acids and polyhydric alcohols. Examples of the polyhydric alcohol include trimethylolpropane (TMP), pentaerythritol (PE), dipentaerythritol (DPE), neopentyl glycol (NPG), 2-methyl-2-propyl-1,3-propane. Examples thereof include diol (MPPD).

  As the monobasic acid, monovalent fatty acids having 4 to 16 carbon atoms are mainly used. Specifically, butyric acid, valeric acid, caproic acid, caprylic acid, enanthic acid, pelargonic acid, capric acid, undecanoic acid, lauric acid, mysteric acid, palmitic acid, beef tallow fatty acid, shalelic acid, caproleic acid, palmitoleic acid, petrothelin Examples include acids, oleic acid, elaidic acid, asclepic acid, vaccenic acid, sorbic acid, linoleic acid, linolenic acid, abinic acid, and ricinoleic acid. The monobasic acid to be reacted with the polyhydric alcohol may be one type or two or more types.

Furthermore, examples of the polyol ester oil include a complex ester oil which is an oligoester of a mixed fatty acid of a monobasic acid and a dibasic acid and a polyhydric alcohol.
Furthermore, examples of the glycol oil include water-insoluble monool-type glycol oil, water-insoluble diol-type glycol oil, and water-soluble monool-type glycol oil.
These base oils may be used individually by 1 type, and may use multiple types together.

[Additives]
In order to further improve the various performances, the lubricant composition G may be added with additives generally used for grease. For example, antioxidants, rust inhibitors, antiwear agents, extreme pressure agents, oiliness improvers, metal deactivators and the like can be mentioned.
Examples of the antioxidant include amine-based antioxidants, phenol-based antioxidants, sulfur-based antioxidants, zinc dithiophosphate, and zinc dithiocarbamate. Examples of the rust preventive include sulfonic acid metal salts, ester-based rust preventives, amine-based rust preventives, naphthenic acid metal salts, and succinic acid derivatives. Examples of extreme pressure agents include phosphorus extreme pressure agents, zinc dithiophosphate, and organic molybdenum. Examples of oiliness improvers include fatty acids and animal and vegetable oils. Examples of the metal deactivator include benzotriazole.

These additives may be used independently and may be used in combination of 2 or more types as appropriate. The total content of additives in the lubricant composition G is not particularly limited as long as the object of the present invention is not impaired.
In addition, this embodiment shows an example of this invention and this invention is not limited to this embodiment. For example, in the present embodiment, a deep groove ball bearing has been described as an example of the rolling device, but the present invention can be applied to various types of other rolling bearings. For example, radial rolling bearings such as angular contact ball bearings, self-aligning ball bearings, cylindrical roller bearings, tapered roller bearings, needle roller bearings, and self-aligning roller bearings, and thrust types such as thrust ball bearings and thrust roller bearings This is a rolling bearing. Furthermore, the present invention can be applied not only to rolling bearings but also to various types of various rolling devices. For example, a ball screw, a linear guide device, a linear motion bearing, or the like.

Hereinafter, the present invention will be described more specifically with reference to examples. First, the manufacture example of a lubricant composition is shown.
[Example 1]
A stainless beaker was charged with 96 g of water-insoluble monool glycol oil and 4 g of dibenzylidene sorbitol, and the mixture was heated to 180 ° C. and stirred. When the dibenzylidene sorbitol was completely dissolved, the mixture was poured into a water-cooled aluminum vat, and the vat was cooled with running water to obtain a gel. And the grease of Example 1 was obtained by processing the obtained gel-like thing with a three roll mill.
The kinematic viscosity at 40 ° C. of the water-insoluble monool-type glycol oil that is a base oil is 33 mm ² / s. The content of the gelling agent (dibenzylidene sorbitol) in the grease is 4% by mass.

[Example 2]
A grease of Example 2 was obtained in substantially the same manner as in Example 1 except that diester oil was used as the base oil and the mixture was heated and stirred to 195 ° C. The kinematic viscosity at 40 ° C. of the diester oil as the base oil is 27 mm ² / s. The content of the gelling agent (dibenzylidene sorbitol) in the grease is 5% by mass.

Example 3
A grease of Example 3 was obtained in substantially the same manner as in Example 1, except that a water-soluble monol glycol oil was used as the base oil and the mixture was heated to 150 ° C. with stirring. In addition, the kinematic viscosity at 40 ° C. of the water-soluble monol glycol oil as the base oil is 30 mm ² / s. The content of the gelling agent (dibenzylidene sorbitol) in the grease is 4% by mass.

[Comparative Example 1]
The grease of Comparative Example 1 was obtained in substantially the same manner as in Example 1 except that ether oil was used as the base oil and the mixture was heated and stirred to 210 ° C. In addition, the kinematic viscosity at 40 ° C. of the ether oil as the base oil is 33 mm ² / s. The content of the gelling agent (dibenzylidene sorbitol) in the grease is 5% by mass.

[Comparative Example 2]
The same operation as in Example 1 was performed except that poly α-olefin oil was used as the base oil and the mixture was heated and stirred to 210 ° C. However, dibenzylidene sorbitol did not dissolve and the mixture did not gel, so no grease was obtained. This is considered to be caused by the use of a poly α-olefin oil having no polarity and a poor affinity with dibenzylidene sorbitol as the base oil.
The kinematic viscosity of poly α-olefin oil at 40 ° C. is 31 mm ² / s. Moreover, content of the gelatinizer (dibenzylidene sorbitol) in a mixture is 5 mass%.

[Comparative Example 3]
The grease of Comparative Example 3 was obtained in substantially the same manner as in Example 1 except that tricresyl phosphate was used as the base oil and the mixture was heated and stirred to 140 ° C. The kinematic viscosity of tricresyl phosphate, which is a base oil, at 40 ° C. is 24 mm ² / s. The content of the gelling agent (dibenzylidene sorbitol) in the grease is 5% by mass.
[Comparative Example 4]
The grease of Comparative Example 4 was obtained in substantially the same manner as in Example 1 except that tricresyl phosphate was used as the base oil and the mixture was heated and stirred to 140 ° C. The kinematic viscosity of tricresyl phosphate, which is a base oil, at 40 ° C. is 24 mm ² / s. The content of the gelling agent (dibenzylidene sorbitol) in the grease is 3% by mass.

The greases of Examples 1 to 3 and Comparative Examples 1, 3, and 4 were subjected to the following flow-recovery test.
Grease was put into a rotation-revolution stirrer and a shearing force was applied, and then the immiscible penetration was measured. And the difference with the immiscible penetration measured before giving a shear force was computed. The fluidity of the grease was evaluated based on this difference (viscosity change due to application of shear force).

Further, after applying the shearing force as described above, the application of the shearing force was stopped and the mixture was allowed to stand at 40 ° C. for 1 hour. Then, the immiscible consistency of the grease was measured to evaluate the viscosity recovery rate. The viscosity recovery rate calculated by the following equation was used for evaluating the viscosity recovery rate.
Viscosity recovery rate (%) = ([immiscible consistency after applying shear force] − [immiscible consistency after leaving]] / ([immiscible consistency after applying shear force] − [before applying shear force) Immiscible consistency])

These evaluation results are shown in Tables 1 and 2 and the graph of FIG. 2 together with the relative dielectric constant of the base oil. The grease fluidity by applying the shearing force was determined to be acceptable if the immiscible consistency after applying the shearing force was 380 or more (a degree that naturally flows when tilted). The viscosity recovery speed of the grease was determined to be acceptable if the viscosity recovery rate was 80% or more.
As can be seen from Tables 1 and 2, the greases of Examples 1 to 3 have a relative dielectric constant of 3 or more at a frequency of 1 kHz of the base oil, although the fluidity of the grease is greatly improved by applying a shearing force. Since it is 50 or less, the viscosity recovery speed is very fast.

On the other hand, in the grease of Comparative Example 1, although the fluidity of the grease was greatly improved by applying a shearing force, the viscosity recovery speed was very slow because the relative dielectric constant of the base oil at a frequency of 1 kHz was less than 3.
The grease of Comparative Example 3 uses tricresyl phosphate having a good affinity for dibenzylidene sorbitol as a base oil. However, since the relative dielectric constant at a frequency of 1 kHz is too large, the dibenzylidene sorbitol content is 5 When the content was mass%, even when a shearing force was applied, it did not change from gel to oil and did not flow sufficiently.
Furthermore, the grease of Comparative Example 4 has a dibenzylidene sorbitol content of 3% by mass, and thus the fluidity of the grease is improved by applying shearing force, but the dibenzylidene sorbitol content is insufficient. The viscosity recovery rate was very slow.

It is a longitudinal cross-sectional view which shows the structure of the deep groove ball bearing which is one Embodiment of the rolling device which concerns on this invention. It is a graph which shows the correlation with the relative dielectric constant in the frequency of 1 kHz of base oil, and the viscosity recovery factor of grease.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inner ring 1a Raceway surface 2 Outer ring 2a Raceway surface 3 Rolling element G Lubricant composition

Claims (4)

In the lubricant composition containing a base oil and a gelling agent, the base oil and an ester oil or glycol oil dielectric constant at a frequency of 1kHz is 3 or more and 50 or less, the gelling agent and dibenzylidene sorbitol, The content of the gelling agent in the lubricant composition is 2% by mass or more and 10% by mass or less, and the immiscible consistency after applying the shearing force measured after applying the shearing force and before applying the shearing force From the immiscible penetration before applying the shearing force, and the immiscible penetration after standing after applying the shearing force and leaving it at 40 ° C. for 1 hour. A lubricant composition having a viscosity recovery rate calculated by using an equation of 80% or more and an immiscibility consistency after application of the shearing force of 380 or more .
Viscosity recovery rate (%) = ([immiscible consistency after applying shear force] − [immiscible consistency after leaving]] / ([immiscible consistency after applying shear force] − [before applying shear force) Immiscible consistency]) The base oil is a diester oil or monool glycol oil having a relative dielectric constant of 3 to 50 at a frequency of 1 kHz, and the content of the gelling agent in the lubricant composition is 4% by mass to 5% by mass. The lubricant composition according to claim 1. The lubricant composition according to claim 1 or 2, wherein the shearing force is applied using a rotation-revolution stirrer. An inner member having a raceway surface on the outer surface, an outer member having a raceway surface opposite to the raceway surface of the inner member, and arranged on the outer side of the inner member, and rolling between the both raceway surfaces A rolling device comprising a plurality of freely arranged rolling elements and a lubricant that lubricates between the raceway surface and the rolling elements, wherein the lubricant is any one of claims 1 to 3. A rolling device comprising the lubricant composition described in 1.

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