JP6281086B2 - Non-diffusible fluorine-based lubricant composition - Google Patents

Description

  The present invention relates to a fluorine-based lubricant composition in which perfluoropolyether oil is prevented from diffusing.

  Grease is often classified by its base oil and thickener. Among them, grease obtained by increasing perfluoropolyether oil with a fluorine-based polymer such as polytetrafluoroethylene or an inorganic thickener is called fluorine grease. Fluorine grease is expensive, but due to its excellent performance derived from its base oil, it has extremely high lubricity, heat resistance, oxidation stability, resistance to resin, resistance to rubber, low dust generation, and chemical resistance. It is a grease that boasts multiple functions.

  This fluorine grease is often used particularly for precision and delicate parts such as home appliances. Since home appliances are handled with no maintenance for 10 years or more depending on the product, the multi-functionality of fluorine grease can sufficiently satisfy the required specifications.

  However, as described above, although fluorine grease is a very multifunctional grease, it has a drawback that oil diffusion (oil bleeding) is larger than that of soap grease used for general purposes. If oil adheres to the electrical contact part or the lens part due to this oil diffusion, there is a possibility of causing malfunction or the like. Such oil diffusion largely depends on the viscosity of the base oil, the wettability between the base oil and the application member, and the surface shape of the application member.

  As a technique related to prevention of oil diffusion of grease, for example, a technique described in Patent Document 1 is known. Patent Document 1 describes that suppression of exudation from grease is achieved by blending a synthetic surfactant with a fluorosurfactant. However, the diffusion inhibitor used here has no effect on perfluoropolyether oil.

  On the other hand, for example, Patent Document 2 discloses a non-diffusible fluorine grease composition in which 0.1 to 50% by weight of silicone oil is mixed with fluorine grease as a base oil diffusion prevention measure for fluorine grease. However, since the perfluoropolyether oil and the silicone oil are not compatible and have a large specific gravity difference, the bleed phenomenon of the silicone oil, that is, the separation is increased with respect to the lubricant surface. Moreover, since the silicone oil with poor lubricity is included, the load bearing ability particularly in metal-to-metal is lowered, and depending on the blending amount, the load bearing ability of perfluoropolyether oil is lowered. Furthermore, since the low molecular weight siloxane component in the silicone oil volatilizes and may cause contact failure, there is a problem that it is difficult to use at the contact site.

  Thus, there is no technique for preventing oil bleeding while maintaining the high performance of perfluoropolyether oil. The scope of application of perfluoropolyether oil and fluorine grease containing perfluoropolyether oil has greatly expanded with the development of each field, and there is a demand for a lubricant having high performance and low oil bleeding. Yes.

Japanese Patent Publication No. 4-46999 Japanese Patent No. 4146551

  The present invention has been proposed in view of such a conventional situation, and the diffusion (oil bleeding) of the perfluoropolyether oil is maintained while maintaining the high performance of the perfluoropolyether oil and the fluorine grease. It aims at providing the fluorine-type lubricant composition which can be made small.

  As a result of intensive studies to achieve the above-described object, the present inventors have been able to suppress bleeding of the perfluoropolyether oil without deteriorating the performance of the perfluoropolyether oil. It was found that it works effectively.

  That is, the lubricant according to the present invention is characterized in that the perfluoropolyether oil contains at least one selected from compounds represented by the following formulas (I) to (III).

Here, the perfluoroether group (Rf) in the above formulas (I) to (III) is C _n F _{2n + 1} O (CF ₂ CF ₂ O) _m CF ₂ CH ₂ — (n = 1 to 4, m = 0-2).

  According to the fluorine-based lubricant composition of the present invention, oil diffusion (oil bleeding) can be effectively prevented without impairing the properties of the lubricant containing perfluoropolyether oil. Moreover, according to the fluorine-type lubricant composition which concerns on this invention, it can be applied to various places as a more versatile lubricant, and it can incorporate in various products and can provide a long-life product.

Hereinafter, specific embodiments of the fluorine-based lubricant composition according to the present invention (hereinafter referred to as “this embodiment”) will be described in detail. In addition, this invention is not limited to the following embodiment, In the range which does not change the summary of this invention, a change is possible.
1. Anti-diffusion agent Lubricant composition (fluorine-based lubricating oil composition, fluorine grease composition)
3. Example

<< 1. Diffusion inhibitor >>
(1-1. Configuration and action of diffusion inhibitor)
The anti-diffusion agent according to the present embodiment is a fluorine-based lubricating oil containing perfluoropolyether oil and a fluorine grease in which perfluoropolyether oil is increased with a thickener (hereinafter collectively referred to as “lubricant”). Is used in addition to the above. The diffusion inhibitor is for preventing diffusion of perfluoropolyether oil contained in the lubricant.

  Specifically, the diffusion inhibitor according to the present embodiment contains one or more fluorine compounds selected from the following formulas (I) to (III) as active ingredients.

Here, the perfluoroether group (Rf) in the above formulas (I) to (III) is C _n F _{2n + 1} O (CF ₂ CF ₂ O) _m CF ₂ CH ₂ — (n = 1 to 4, m = 0-2).

  According to the diffusion inhibitor as described above, by containing the above-described fluorine compound as an active ingredient, oil diffusion (oil bleeding) without impairing the characteristics of the fluorine-based lubricant containing perfluoropolyether oil. Can be effectively prevented. Further, the diffusion inhibitor does not lower the load bearing capacity of perfluoropolyether oil like silicone oil. And the lubricating oil and grease containing this diffusion inhibitor can be applied to various places as a more versatile lubricant. Specifically, for example, the present invention can be favorably applied to a part where oil bleeding is a problem, such as an electrical contact part or a lens part in home appliances. Therefore, it is possible to provide a long-life product by being incorporated in various products.

(1-2. Perfluoropolyether oil (base oil) and oil diffusion mechanism)
Here, examples of the perfluoropolyether oil as the base oil include those having structures represented by the following general formulas (1) to (4). Specifically, for example, Krytox series (manufactured by DuPont), Fomblin Y series (manufactured by Solvay Specialty Polymers Japan), Fomblin M series (manufactured by Solvay Specialty Polymers Japan), Fomblin W series (manufactured by Solvay Specialty Polymers Japan), Fomblin Commercial products such as Z series (manufactured by Solvay Specialty Polymers Japan) and demnum S series (manufactured by Daikin Industries, Ltd.) can be used.

F— (CFCF ₃ —CF ₂ —O—) _n —CF ₂ —CF ₃ General formula (1)
(In the general formula (1), n is 0 or a positive integer.)
CF _3- (O-CFCF ₃ -CF ₂ ) _p- (O-CF _2- ) _q -O-CF ₃
General formula (2)
(Note that p and q in the general formula (2) are each independently 0 or a positive integer.)
_{F- (CF 2 -CF 2 -CF 2} -O-) r -CF 2 -CF 3 Formula (3)
(In the general formula (3), r is 0 or a positive integer.)
CF _3- (O-CF ₂ -CF _2- ) _s- (O-CF _2- ) _t -O-CF ₃
General formula (4)
(In addition, s and t in the general formula (4) are each independently 0 or a positive integer.)

The viscosity of perfluoropolyether oil is a factor that greatly affects oil diffusion. When the viscosity increases, the low temperature property of the perfluoropolyether oil itself deteriorates. Therefore, the diffusion inhibitor according to the present embodiment can be particularly preferably used for perfluoropolyether oil having a viscosity of 10 to 600 mm ² / s at 40 ° C. In addition, the chemical structure of the perfluoropolyether oil is not limited in any way, and the above-described straight chain type as represented by the general formulas (3) and (4) and the side chain type as represented by the general formulas (1) and (2). It can use suitably for both.

  The diffusion of perfluoropolyether oil contained in the lubricant as a base oil is considered to occur when the base oil expands and spreads by capillary action through the fine roughness of the base surface (the surface where the lubricant is applied). . Since most of the ground surface has a certain amount of roughness, it is essential to effectively prevent the diffusion at a site where oil diffusion is disliked. The oil diffusion distance greatly depends on the viscosity of the oil.

(1-3. Mechanism of preventing oil diffusion)
The diffusion inhibitor according to the present embodiment is considered to prevent oil diffusion by the following mechanism. That is, when the diffusion inhibitor described above is blended with a perfluorinated polyether oil or a fluorine grease containing a perfluoropolyether oil with respect to a lubricant, the diffusion preventing agent coats the base surface in advance. At this time, polar groups such as a carboxyl group and a hydroxyl group in the fluorine compound contained in the diffusion inhibitor are oriented on the base surface side, and the perfluoropolyether group faces the atmosphere side. On the other hand, in the diffusion inhibitor remaining in the perfluoropolyether oil, the polar group is directed to the atmosphere side. Then, it is considered that this polar group repels the perfluoropolyether group coated in advance on the base surface, thereby preventing the perfluoropolyether oil from diffusing.

(1-4. Compounding amount)
The blending amount of the diffusion inhibitor is not particularly limited, and is preferably determined appropriately according to the chemical structure and physical properties of the perfluoropolyether oil. Specifically, it can mix | blend in the ratio of about 0.1-10 mass% with respect to a lubricant, for example. If the blending amount is too small, the oil diffusion preventing effect may not be sufficiently exhibited. On the other hand, if the blending amount is too large, the diffusion preventing effect reaches its peak and the ratio of the lubricating oil component decreases. Therefore, lubricity may be reduced.

  As mentioned above, the diffusion of perfluoropolyether oil depends on its viscosity. Therefore, it is preferable to change the blending amount of the diffusion inhibitor according to the viscosity of the perfluoropolyether oil blended as the base oil. In general, perfluoropolyether oil is more easily diffused as its viscosity is lower, so it is necessary to increase the amount of the diffusion inhibitor. In light of the above-mentioned diffusion prevention mechanism, the base contact surface to which the lubricant is applied is in a state where the surface coating of the diffusion prevention agent and the diffusion of the base oil compete with each other, and the lower the oil viscosity, the more fluid Base oil diffusion may occur before the diffusion inhibitor coats the surface. Therefore, in the case of a perfluoropolyether oil having a low viscosity, it is preferable to adjust so as to increase the amount of the diffusion inhibitor.

Specifically, for example, in the case of a perfluoropolyether oil having a kinematic viscosity at 40 ° C. of less than 100 mm ² / s, the diffusion inhibitor may be blended at a ratio of about 0.1 to 10% by mass with respect to the lubricant. It is more preferable to mix at a ratio of preferably about 0.1 to 5.0% by mass. Moreover, in the case of a perfluoropolyether oil having a kinematic viscosity of a base oil at 40 ° C. of 100 mm ² / s or more, a diffusion inhibitor is blended at a ratio of about 0.1 to 5.0% by mass with respect to the lubricant. It is more preferable that the amount is about 0.1 to 3.0% by mass.

≪2. Lubricant composition (lubricating oil composition, grease composition) >>
(About lubricant composition)
The lubricant composition according to the present embodiment is a fluorine-based lubricant composition and a fluorine grease composition obtained by containing the above-described diffusion inhibitor in perfluoroether oil as a base oil.

Examples of the perfluoropolyether oil include those having structures represented by the general formulas (1) to (4) as described above. Among them, it is preferable to use one having a viscosity of 10 to 600 mm ² / s at 40 ° C. from the viewpoint that oil diffusion can be more effectively prevented.

  When the fluorine grease composition is used, the thickener for increasing the perfluoropolyether oil is not particularly limited, but polytetrafluoroethylene is preferably used. Polytetrafluoroethylene has a high affinity with perfluoropolyether oil and itself has high lubricity.

  Among these, it is preferable to use polytetrafluoroethylene having an average particle size of 10.0 μm or less. As the particle size of the polytetrafluoroethylene is finer, the contact area with the perfluoropolyether oil becomes larger, so that the effect of reducing the oil separation of the perfluoropolyether oil is recognized. When polytetrafluoroethylene having an average particle size of more than 10.0 μm is used, the contact area with the perfluoropolyether oil is reduced, that is, the affinity is reduced. Therefore, even when the same amount is blended, the oil separation is larger than that having an average particle size of 10.0 μm or less, the consistency is increased, and the fluidity is increased. It tends to happen. By increasing the blending amount of polytetrafluoroethylene, it is possible to reduce the consistency of the grease and the amount of oil separation, but since the ratio of solid components in the grease increases, the viscosity of the grease increases, handling and Torque at low temperatures will increase. Thus, as polytetrafluoroethylene, the finer the particle diameter, the greater the affinity with perfluoropolyether oil, which is preferable, and the average particle diameter is preferably 10.0 μm or less, more preferably 0.1 μm to 5. Use one with 0 μm.

  Further, as described above, the thickener is not limited to polytetrafluoroethylene, and those having high affinity with perfluoropolyether oil can be suitably used. Specifically, for example, polytetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride and the like can be mentioned. It is done. Depending on the application, powders such as silica aerogel, boron nitride, aluminum nitride, calcium carbonate, calcium phosphate, zinc oxide, zinc sulfide, talc, graphite, molybdenum disulfide, melanin cyanuric acid adduct, ultrahigh molecular weight polyethylene, etc. It can also be used. These thickeners also have a particle size and a content with which oil separation is small and an appropriate consistency and grease viscosity can be obtained. The content of the thickener varies depending on the average particle diameter and the type of the thickener as described above, but is 1 to 50% by mass with respect to the entire lubricant composition. For example, general polytetrafluoro In the case of ethylene, it is about 10-50 mass%, and in the case of a silica airgel, it is about 1-10 mass%.

  The fluorine-based lubricating oil and fluorine grease composition may contain various additives such as a solid lubricant for improving lubricity, a friction modifier, a metal corrosion inhibitor, and a rust inhibitor.

(2-2. Manufacturing method of lubricant composition)
This lubricant composition can be produced by a well-known general method. Specifically, for example, in the case of a fluorine grease composition, a grease base is prepared by kneading perfluoroether oil as a base oil and a thickener, and the above-mentioned diffusion preventing agent is placed in the obtained grease base. Add a certain amount and disperse. Further, various additives are added and kneaded as necessary. Thereby, a non-diffusible fluorine grease composition can be obtained.

  In the case of a fluorine-based lubricating oil composition, a predetermined amount of a diffusion inhibitor is added to the perfluoroether oil of the base oil and stirred. Further, various additives are added and kneaded as necessary. Thereby, a non-diffusible fluorine-type lubricating oil composition can be obtained.

  The kneading treatment or dispersion treatment can be performed using a known stirring / dispersing treatment apparatus such as a three-roll mill, a universal stirrer, a homogenizer, or a colloid mill. In addition, it is not restricted to adding each component in order and kneading | mixing as mentioned above, You may knead | mix each component simultaneously.

≪3. Examples >>
Examples for which the present invention is applied will be described below for the purpose of clarifying the superiority of the present invention. However, the present invention is not limited to the following examples.

<Diffusion inhibitor>
(Diffusion inhibitor A)

  First, stir bar, 1H-, 1H-Perfluoro-3,6,9-trioxatridecan-1-ol (5.52 g, 10.1 mmol), chloroform (stabilizer using amylene) (20 mL) ), Hexamethylene diisocyanate (0.8 mL, 5.0 mmol) and dibutyltin dilaurate (45 μL, 0.75 μmol) were added, and the mixture was stirred at room temperature for 6 days. Next, the reaction solution was concentrated to such an extent that it was not dried by an evaporator while being heated at 40 ° C., methanol (30 mL) was added, and the mixture was vigorously stirred at 40 ° C. for 30 minutes, and the mixture was left in the refrigerator for 1 hour. Next, the supernatant was removed by decantation, methanol (30 mL) was added again, the mixture was heated and stirred, and then allowed to stand in the refrigerator for 2 hours. Then, the supernatant was removed by decantation, and the precipitate was concentrated and dried with an evaporator and a vacuum pump to obtain diffusion inhibitor A (4.83 g, 3.82 mmol).

(Diffusion inhibitor B)

  First, stir bar, 1H-, 1H-Perfluoro-3,6,9-trioxatridecan-1-ol (5.48 g, 10.0 mmol), chloroform (stabilizer using amylene) (20 mL) ), 1,12-diisocyanatododecane (1.27 g, 5.05 mmol) and dibutyltin dilaurate (45 μL, 0.75 μmol) were added, and the mixture was stirred at room temperature for 6 days. Next, the reaction solution was concentrated to such an extent that it was not dried by an evaporator while being heated at 40 ° C., methanol (30 mL) was added, and the mixture was vigorously stirred at 40 ° C. for 30 minutes, and the mixture was left in the refrigerator for 1 hour. Next, the supernatant was removed by decantation, methanol (30 mL) was added again, the mixture was heated and stirred, and then allowed to stand in the refrigerator for 2 hours. Then, the supernatant was removed by decantation, and the precipitate was concentrated and dried with an evaporator and a vacuum pump to obtain a diffusion inhibitor B (6.26 g, 4.64 mmol).

(Diffusion inhibitor C)

  To a 50 mL eggplant flask, a stir bar, 1H-, 1H-Perfluoro-3,6,9-trioxatridecan-1-ol (5.49 g, 10.0 mmol), chloroform (using amylene as a stabilizer) (20 mL), Trimethylhexamethylene diisocyanate (2,2,4-, 2,4,4-mixture) (1.01 g, 4.80 mmol) and dibutyltin dilaurate (45 μL, 0.75 μmol) were added, and 6 days at room temperature. Stir. Next, the reaction solution was concentrated to such an extent that it was not dried by an evaporator while being heated at 40 ° C., methanol (30 mL) was added, and the mixture was vigorously stirred at 40 ° C. for 30 minutes, and the mixture was left in the refrigerator for 1 hour. Next, the supernatant was removed by decantation, methanol (30 mL) was added again, the mixture was heated and stirred, and then allowed to stand in the refrigerator for 2 hours. Then, the supernatant was removed by decantation, and the precipitate was concentrated and dried with an evaporator and a vacuum pump to obtain a diffusion inhibitor C (4.43 g, 3.39 mmol).

<Lubricant composition>
In Examples 1 to 16 and Comparative Examples 1 to 3, a lubricant composition (grease composition, lubricating oil composition) containing the above-described diffusion inhibitor at a blending ratio shown in Tables 1 to 3 below was prepared. . The blending amount is represented by “mass%”.

  Here, as the perfluoropolyether oil A serving as the base oil, demnum S-65 manufactured by Daikin Industries, Ltd. was used. Further, Krytox GPL 107 manufactured by DuPont Co., Ltd. was used as perfluoropolyether oil B.

  As the thickener, polytetrafluoroethylene (manufactured by DuPont, ZONYL TLP 10F-1) was used.

  The fluorine grease compositions (Examples 1 to 11) were produced by the following method. That is, perfluoropolyether oil and polytetrafluoroethylene were kneaded, a diffusion inhibitor was added, and then a dispersion treatment was performed with a three-roll mill to prepare each grease composition. On the other hand, the fluorine grease compositions of Comparative Examples 1 and 2 were prepared by kneading perfluoropolyether oil and polytetrafluoroethylene, performing dispersion treatment with a three-roll mill, and defoaming.

  The fluorine lubricating oil compositions (Examples 12 to 16) were produced by the following method. That is, a diffusion inhibitor was added to perfluoropolyether oil, and after stirring using a dissolver, defoaming was performed to prepare each fluorine lubricating oil composition. On the other hand, the fluorolubricating oil composition of Comparative Example 3 used perfluoropolyether oil as it was.

<Diffusion test and evaluation>
About the lubricant composition produced in Examples 1-16 and Comparative Examples 1-3, the test (diffusivity test) about oil (perfluoroether oil) spreading | diffusion was done.

  In the oil diffusion test, first, each grease was applied to a 2000th wrapping paper in a cylindrical shape with a diameter of 16 mm and a height of 2 mm, and left in a constant temperature bath at 60 ° C. for 24 hours, and the outer periphery of the cylindrical grease The average distance from the oil to the short part of the oil oozing out was determined. For the perfluoropolyether oil alone, 10 μL of lubricating oil was dropped and left in an environment of 25 ° C. for 24 hours to determine the average distance from the outer periphery of the oil before leaving to the short part of the oil that had oozed out. Asked. And compared with Comparative Examples 1-3 (blank) which is not mix | blending a diffusion inhibitor, it performed by evaluating how much the diffusion distance of the oil could be reduced. In addition, Examples 1-7 were compared with Comparative Example 1, and Examples 8-11 were compared with Comparative Example 2.

  In addition, although the result of each oil diffusion test and evaluation of the oil diffusion prevention effect are shown in Tables 1 to 3 below, in the evaluation, the diffusion distance reduction effect is 10% or more compared to the blank (-). The ones that were present were marked with “◯”, and those that had a reduction effect of 50% or more were marked with “◎”.

(Examples 1-3 (Test on Fluorine Grease Composition))
First, as Examples 1 to 3, the oil diffusion preventing effect in a fluorine grease composition in which the above-described diffusion inhibitor was blended with perfluoropolyether oil as a base oil was tested. Table 1 below shows the composition and test results of the grease composition.

  As shown in Table 1, in the fluorine grease compositions of Examples 1 to 3, diffusion of perfluoropolyether oil, which is a base oil, as compared with Comparative Example 1 (blank) in which no diffusion inhibitor was blended It was confirmed that In any of the results, it was confirmed that the diffusion of perfluoropolyether oil was suppressed, and in particular, the compounds of Examples 1 and 3 did not diffuse at all, and the oil diffusion could be prevented more effectively.

(Examples 1, 4 to 11 (examination of blending amount))
Next, as Examples 1 and 4 to 11, diffusibility test when the blending amount of the anti-diffusion agent A that exhibits the oil diffusion preventing effect particularly remarkably in the results shown in Table 1 above is changed. Carried out. Table 2 below shows the grease composition and test results.

  As shown in Table 2, it was found that the anti-diffusion effect was exhibited from the 0.1% formulation, and the anti-diffusion effect was dramatically exhibited from the 1.0% formulation.

(Examples 12 to 16 (examination of blending amount))
Next, as Examples 12 to 16, for the fluorine-based lubricating oil composition in which the diffusion preventing agent A that exhibits the oil diffusion preventing effect particularly notably in the perfluoropolyether oil that is the base oil, The diffusivity test when changed was carried out. Table 3 below shows the composition and test results of the lubricating oil.

  When anti-diffusion agent A was added to the fluorinated lubricant, any anti-diffusion effect was observed, and a remarkable anti-diffusion performance was exhibited at 1.0% or more.

  According to the lubricant composition of the present invention, it is possible to effectively prevent the perfluoropolyether oil from diffusing. As a result, while maintaining the high performance of perfluoropolyether oil, it becomes possible to improve the oil diffusion that could not be achieved in the past, and to parts where oil diffusion of lubricants is disliked (for example, electrical contact parts and lens parts) Also, it can be suitably used, and good lubricating performance can be exhibited.

Claims (1)

A lubricant composition comprising perfluoropolyether oil containing at least one selected from compounds represented by the following formulas (I) to (III).

Here, the perfluoroether group (Rf) in the above formulas (I) to (III) is C _n F _{2n + 1} O (CF ₂ CF ₂ O) _m CF ₂ CH ₂ — (n = 1 to 4, m = 0-2).