Metal-resin lubricating grease composition

Abstract

The present invention relates to a grease composition for metal-resin lubrication. Provided are a grease composition for which the lubricity between resin and metal is excellent, and a resin sliding member and a resin / metal inter-sliding member in which the use of the grease composition inhibits friction / wear, and in which the operability and long life of the product are improved. A resin grease composition G for a sliding surface made of resin, which contains, as base oil, a fluorine-based base oil (kinematic viscosity at 40°C: 300 mm 2 / s or more) and a synthetic hydrocarbon oil, as thickening agent, a fluorine-based thickening agent and a lithium soap thickening agent or a lithium complex soap thickening agent, as extreme pressure additive, and a fluorine-based surfactant, and a resin sliding member (sliding switch 101) having a sliding surface made of resin using the grease composition G.

Description

TECHNICAL FIELD

[0001] The present application relates to a grease composition for resin lubrication, and particularly to a grease composition for resin lubrication between a metal and a resin. BACKGROUND

[0002] In Patent Literature 1, a slide switch (resin slide member) achieving improved waterproofness is proposed.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Publication No. 2016-139589

[0006] When a slide member having a slide surface made of resin (hereinafter, referred to as a resin slide surface) is used in an environment where contact with water is likely to occur, there is a tendency that a grease composition applied to the slide surface is easily removed from the slide surface. In the case where the grease composition is removed from the resin slide surface, a sharp rise in frictional force on the slide surface, an increase in wear amount, and even a shortening of the life of a product having the resin slide surface can be caused. Therefore, a grease which is not removed from the slide surface even when a resin slide member is used in an environment where contact with water is likely to occur, for example, in a water environment, and which can achieve suppression of friction / wear is desired.

[0007] Moreover, in recent years, a grease which can achieve suppression of friction / wear of a resin slide surface in a resin slide member as described above, using a slide member having a surface opposite to the resin slide surface made of metal (i.e., a resin / metal interfacial slide member), like a slide member having a surface opposite to the resin slide surface made of resin, is strongly desired. SUMMARY

[0008] An object of the present application is to provide a grease composition for resin / metal interfacial lubrication which is excellent in lubricity, and to provide a resin slide member and a resin / metal interfacial slide member which can achieve improved operability and long life of a product by using the grease composition to suppress friction / wear.

[0009] One aspect of the present application is a grease composition for resin lubrication which is used for a slide surface made of resin, the grease composition for resin lubrication containing: a fluorine-based base oil and a synthetic hydrocarbon oil, a fluorine-based thickener and a lithium soap thickener or a lithium complex soap thickener, a fluorine-based surfactant, and an extreme pressure additive, the fluorine-based base oil having a kinematic viscosity at 40°C of 300 mm 2 / s or more.

[0010] Further, the present application relates to a resin sliding member having a sliding surface made of resin using the grease composition for resin lubrication.

[0011] The present application further relates to a resin / metal inter-sliding member having a sliding surface made of resin using the grease composition for resin lubrication, and a counter surface of metal opposite to the sliding surface. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 is a schematic view for explaining the structure of one mode of the sliding member of the present application (sliding switch), and Figure 1 (a) of FIG. 1 is a cross-sectional view of the sliding switch viewed from the front with the switch turned off, and Figure 1 (b) of FIG. 1 is a cross-sectional view of the sliding switch viewed from the front with the switch turned on.

[0013] Figure 2 is a schematic view for explaining the structure of one mode of the sliding member of the present application (sliding switch), and Figure 1 is a cross-sectional view of (a) of FIG. 1 taken along the line X-X.

[0014] Figure 3 is a schematic view for explaining the structure of one mode of the sliding member of the present application (multi-stage gear device), and Figure 3 (a) of FIG. 3 is a front view of the multi-stage gear device, Figure 3 (b) of FIG. 3 is a side view (including a partial cross-section) of the multi-stage gear device.

[0015] Figure 4 is a conceptual view of an apparatus used in a friction and wear test (1) (evaluation of lubricating properties between metal and resin) implemented in the examples.

[0016] Figure 5 is a conceptual view of an apparatus used in a friction and wear test (2) (evaluation of lubricating properties between resin and resin) implemented in the examples.

[0017] Figure 6 is a view showing microscope observation photographs (magnification 200x) of the grease compositions of Comparative Example 2 and Example 2 ((A): Comparative Example 2, (B): Example 2).

[0018] Figure 7 shows the dynamic friction coefficient values of the grease compositions of Comparative Example 2, Example 6, Example 5, Example 2, Example 7, and Comparative Example 6, with respect to the blending amount (0 mass% to 3 mass%) of the fluorine-based surfactant.

[0019] Figure 8The dynamic friction coefficient values of the grease composition in which the addition amount of the fluorine-based surfactant was 2 mass% (O: Comparative Example 9, Examples 1 to 4, Comparative Example 10) and the addition amount of the fluorine-based surfactant was 0 mass% (■: Comparative Example 7, Comparative Examples 1 to 4) relative to the "fluorine-based grease content" (100 mass% to 70 mass%) referred to in the graph, wherein the "fluorine-based grease content" refers to the proportion of the total amount of the fluorine-based base oil and the fluorine-based thickener when the total mass of the fluorine-based base oil, the synthetic hydrocarbon oil, the fluorine-based thickener, and the lithium soap thickener is set to 100.

[0020] Figure 9 The static friction coefficient values of the grease composition of Comparative Example 9, Examples 1 to 4, and Comparative Example 10 relative to the "fluorine-based grease content" (100 mass% to 70 mass%) referred to in the graph, wherein the "fluorine-based grease content" refers to the proportion of the total amount of the fluorine-based base oil and the fluorine-based thickener when the total mass of the fluorine-based base oil, the synthetic hydrocarbon oil, the fluorine-based thickener, and the lithium soap thickener is set to 100.

[0021] BRIEF DESCRIPTION OF DRAWINGS

[0022] 101: sliding switch; 102: housing; 103: cover; 104: first waterproof film; 105: second waterproof film; 106: first fixed contact; 107: second fixed contact; 108: third fixed contact; 109: movable contact; 110: slider; 110a: protrusion; 113: contact operating portion; 114: click spring; 114a: protrusion; 201: multi-stage resin gear device; 202: first-stage gear; 203: second-stage gear; 204: shaft of second-stage gear; 204a: bearing portion (grease application portion); 205: third-stage gear; 206: shaft of third-stage gear; 206a: bearing portion (grease application portion); X: meshing portion of first-stage gear and second-stage gear; Y: meshing portion of second-stage gear and third-stage gear; 211: motor; 211a: motor output shaft; 212: actuator output shaft. DETAILED DESCRIPTION

[0023] As described above, in an environment in contact with water, for example, in an environment in water, in an environment in which dew condensation is likely to occur (hereinafter, also collectively referred to as a water contact environment), there is a problem that grease peeling from a coated surface is likely to occur. For example, the slide switch disclosed in Patent Document 1 is provided with a waterproof sheet made of a resin for improving waterproofness in view of the possibility of use in a water contact environment, and the slide switch performs switching on / off with the waterproof sheet interposed therebetween, as described later. At this time, grease for improving lubricity of the waterproof sheet and the slider, and lubricity of the slider and other contact surfaces is used. However, if the adhesion of the grease is poor, the grease can be removed during use (performance of on / off) of the switch, and thus the frictional force of the slider and the waterproof sheet and the like increases, and wear / damage of the waterproof sheet and the like can occur, and as a result, shortening of the life of the slide switch can occur. In recent years, further miniaturization of the switch member has been pursued, and the load on the waterproof sheet has further increased, and this increases the occurrence of damage of the waterproof sheet and the like, and further shortening of the life of the switch is a concern.

[0024] Further, slide switches vary depending on the kind thereof, and in addition to slide switches in which other contact surfaces, for example, a pawl spring (elastic member) that slides with respect to the slider (resin) is made of a resin, there are slide switches in which the pawl spring is made of a metal. For the grease used for the latter slide switches, it is desirable that not only the lubricity between the waterproof sheet (resin) and the slider (resin) described above be achieved, but also good lubricity between the slider (resin) and the pawl spring (metal) be achieved.

[0025] In the past, as a resin-lubricating grease for a micro slide switch and the like, a fluorine-based grease has been used, and in order to pursue improvement in the adhesion of the grease to the resin in the above-described water contact environment, a mixture of a fluorine-based lubricant and a lithium soap grease as a non-fluorine-based lubricant has been studied, and pursuit of long life of the slide switch has been pursued.

[0026] However, in the case of the above-described mixture of a fluorine-based lubricant and a non-fluorine-based lubricant, it is difficult to say that the lubricity between the resin and the metal is good compared to the case in which a fluorine-based lubricant is used alone. Therefore, in the case in which such a mixture is used in a switch having a slide portion in which the opposite surface to the resin slide surface (slider) is made of a metal (pawl spring), the operability (click feeling) of the slide switch can deteriorate.

[0027] As one factor that affects the above-described lubricity, the good or poor dispersibility of the above-described mixture can be considered. As shown in the results of the examples described later, when a microscope observation photograph of a lubricating grease composition in which a fluorine-based surfactant is compounded (Example 2) and a lubricating grease composition in which no fluorine-based surfactant is compounded (Comparative Example 2) are compared, Figure 6When compared, in the grease composition not blended with the surfactant, a number of agglomerates of about 20 to 30 μm or so were confirmed. The presence of such agglomerates causes an increase in the friction coefficient on the sliding surface, and for example, with respect to the lubricity between the resin and the metal, it is considered to cause deterioration in the switching operability. In addition, when sliding under load is performed in a state where such agglomerates are generated, an increase in the wiping of the grease from the sliding surface is observed, and this can cause abrasion / breakage of the waterproof sheet or the like.

[0028] To solve such a problem, the present inventors and others found that by blending a grease containing a fluorine-based base oil and a synthetic hydrocarbon oil as a base oil, a fluorine-based thickener and a lithium soap thickener or a lithium complex soap thickener as a thickener, and an extreme pressure additive, and in particular, a fluorine-based surfactant, not only the lubricating properties of the grease in a water contact environment are excellent, but also the lubricating properties between the resin and the metal are excellent.

[0029] The resin-lubricating grease composition of the present application (hereinafter, also simply referred to as "the grease composition") is characterized by combining a specific base oil with a specific thickener, and blending a fluorine-based surfactant thereto, as described later. The grease composition imparts excellent lubricating properties to the site of use (the sliding surface), and can impart excellent lubricating properties not only to the opposing surface of the resin, but also to the opposing surface of the metal. The following is described in detail.

[0030] [Resin sliding member and resin / metal inter-sliding member]

[0031] The resin sliding member and the resin / metal inter-sliding member using the resin-lubricating grease composition of the present application are not particularly limited, and for example, sliding switches, gear devices, bearings, and the like can be listed.

[0032] The resin sliding member that is the object of the present application is not particularly limited as long as it is a sliding member having a resin-made sliding surface at least in a part thereof. In addition, the resin / metal inter-sliding member that is the object of the present application is not particularly limited as long as it is a sliding member having a resin-made sliding surface, and an opposing surface of the metal opposite to the sliding surface. Therefore, the resin sliding member and the resin / metal inter-sliding member include not only the sliding switches, the gear devices, the bearings, and the like as described above, but also various resin sliding members and resin / metal inter-sliding members, and these resin sliding members and resin / metal inter-sliding members are also the objects of the present application.

[0033] Further, the resin sliding member of the present application has a resin-made sliding surface (a resin sliding surface of which at least a part is covered with the resin-lubricating grease composition by contacting the resin-lubricating grease composition by coating or encapsulation, which is described later) using the resin-lubricating grease composition described later.

[0034] Furthermore, the resin / metal sliding member of the present invention comprises: a resin sliding surface made of resin using a resin lubricating grease composition described later (a resin sliding surface that is in contact by coating or sealing with the grease composition, thereby at least partially covered by the resin lubricating grease composition), and a metal opposing surface opposite the sliding surface.

[0035] The preferred embodiments of each resin sliding member and resin / metal sliding member will be described in detail below with reference to the accompanying drawings, but the present invention is not limited to the following embodiments.

[0036] [Slide switch]

[0037] Figure 1 This shows a cross-section of the slide switch 101 according to a preferred embodiment of the present invention, viewed from the front. Furthermore, the following will be described... Figure 1 The X-X sectional view of (a) (a view of the slide switch 101 viewed from above) is shown in Figure 2 .

[0038] exist Figure 1 (and Figure 2 In one example shown, the slide switch 101 includes: a housing 102, a cover 103, a first waterproof membrane 104, a second waterproof membrane 105, a first fixed contact 106, a second fixed contact 107, a third fixed contact 108, a movable contact 109, a slider 110, a contact operation part 113, and a pawl spring 114.

[0039] like Figure 1 As shown, the outer shell is formed by combining the housing 102 and the cover 103. The housing 102 is formed of an insulating material, and the cover 103 is formed of a metal such as stainless steel. It should be noted that the cover 103 may also be formed of an insulating material.

[0040] As will be described later, the first waterproof membrane 104 and the second waterproof membrane 105 are provided to improve the waterproofness of the slide switch 101, such as Figure 1 As shown, the first waterproof membrane 104 is attached to the outer surface of the housing 102, and the second waterproof membrane 105 is attached to the inside of the housing 102.

[0041] Furthermore, the first fixing contact 106, the second fixing contact 107, and the third fixing contact 108 are fixed to the housing 102 between the first waterproof membrane 104 and the second waterproof membrane 105. The first fixing contact 106, the second fixing contact 107, and the third fixing contact 108 are separated from each other by the housing 102, thus providing electrical insulation; they are formed of a conductive material. It should be noted that, although not shown, the ends of the first fixing contact 106, the second fixing contact 107, and the third fixing contact 108 are exposed at the bottom of the housing 102, serving as connection terminals for external circuits.

[0042] The movable contact 109 is formed of a conductive material. For example... Figure 1 As shown, the movable contact 109 can be in the separated position (connected position) that is separated from the first fixed contact 106 and the second fixed contact 107. Figure 1 (a) and the contact position (disconnect position) that contacts the first fixed contact 106 and the second fixed contact 107. Figure 1 The displacement between (b)). The movable contact 109 is configured to operate in an unloaded state ( Figure 1 The elastic member in the separated position is formed under (a)).

[0043] The slider 110 is formed of an insulating resin material. For example... Figure 1 As shown in (a), slider 110 is supported inside housing 102. Slider 110 is movable along the longitudinal direction of housing 102 between an open position and an open position. Figure 1 In (a), the range indicated by the two arrows is the movable range of slider 110.

[0044] It should be noted that the cover 103 has a sliding groove 103a extending in the longitudinal direction of the housing 102, and the sliding groove 103a is configured to guide the movement of the slider 110 between the disconnected position and the connected position.

[0045] Furthermore, a contact operation section 113 is provided on the slider 110. The contact operation section 113 is configured such that by moving the slider 110 from the disconnected position to the connected position, the movable contact 109 is displaced from the separated position to the contact position through the second waterproof membrane 105.

[0046] Figure 1 (b) indicates that slider 110 is moved from... Figure 1 The state shown in (a) is the state in which the slider 110 moves towards the connected position along the sliding groove 103a. As the slider 110 moves, the contact operation part 113 provided on the slider 110 displaces the movable contact 109 through the second waterproof membrane 105. When the movable contact 109 contacts the first fixed contact 106 and the second fixed contact 107, the first fixed contact 106 and the second fixed contact 107 are electrically connected via the movable contact 109.

[0047] When the connection between the first fixed contact 106 and the second fixed contact 107 is released, the above operation can be reversed. That is, the slider 110 is moved along the sliding groove 103a to the disconnected position, releasing the pressure of the contact operation part 113 on the movable contact 109. The movable contact 109 returns to the separated position by its own elastic restoring force. That is, the contact state between the movable contact 109 and the first fixed contact 106 and the second fixed contact 107 is released.

[0048] According to the above-described configuration, the first fixed contact 106, the second fixed contact 107, and the movable contact 109 are arranged between the first waterproof film 104 and the second waterproof film 105, and contact / separation of the two is performed through the contact point operation portion 113 provided to the slider 110 with the second waterproof film 105 interposed therebetween. Water can intrude into the housing 102 from the outside through the opening of the sliding groove 103a.

[0049] Further, the slide switch 101 is provided with a pair of pawl springs 114 (elastic members). Each pawl spring 114 is provided with a protrusion 114a. On the other hand, the slider 110 is provided with a pair of protrusions 110a.

[0050] As shown in (a) and (b) of FIG. 10, when the slider 110 moves between the off position (a) and the on position (b), each protrusion 110a of the slider 110 elastically deforms the opposing pawl spring 114 while displacing the protrusion 114a of the pawl spring 114 in the short dimension direction of the housing 102 (the paper vertical direction in (a) and the up-down direction on the paper in (b)). Figure 2 (And Figure 1 ) When the slider 110 moves between the off position (a) and the on position (b), each protrusion 110a of the slider 110 elastically deforms the opposing pawl spring 114 while displacing the protrusion 114a of the pawl spring 114 in the short dimension direction of the housing 102 (the paper vertical direction in (a) and the up-down direction on the paper in (b)). Figure 2 Figure 1 When each protrusion 110a of the slider 110 passes through the protrusion 114a of the opposing pawl spring 114, the elastic restoring force of the pawl spring 114 assists the movement of the slider 110 to the on position or the off position, and further imparts a click feeling to the switch. Figure 1 Figure 2 In the slide switch 101, the second waterproof film 105 is formed of, for example, a polyamide resin such as nylon, a polyphthalamide (PPA) resin material. Further, the slider 110 can be formed of, for example, an insulating resin material such as polyamide (PA), polyphenylene sulfide (PPS), polyphthalamide (PPA). Also, the pawl spring 114 is formed of a springy resin material such as the above-described insulating material, polycarbonate (PC), polyoxymethylene (POM), polyether ether ketone (PEEK), reinforced plastic, a springy metal material such as stainless steel, carbon steel, carbon tool steel, and special steel (cold-rolled steel for springs). Figure 3

[0051]

[0052] ​​​​In the slide switch 101 of the present embodiment, the grease composition G for resin lubrication of the present application is applied to the contact portion of the contact operating portion 113 of the slider 110 with the second waterproof film 105 (the lower portion of the slider 110 is a resin sliding surface), and the contact portion of each of the protrusions 110a of the slider 110 with each of the protrusions 114a of the ratchet spring 114 (each of the protrusions 110a of the slider 110 is a resin sliding surface). That is, the grease composition G for resin lubrication is applied to the resin sliding surface of the slide switch 101. In the slide switch 101, the grease composition G that is excellent in adhesion to the resin sliding surface described later, and further excellent in lubricity of the grease itself is used even in an environment where water intrudes into the housing 102 from the slide groove 103a. Therefore, in the slide switch 101, friction / wear is suppressed, and long life is achieved.

[0053] [GEAR DEVICE]

[0054] As one example of the gear device of the preferred embodiment of the present application, a multi-stage gear device provided in an actuator is described.

[0055] Note that the "multi-stage gear device" in which the grease composition for resin lubrication of the present application is used means a multi-stage gear device in which at least one gear is a resin gear, and in the multi-stage gear device, a resin gear and a gear composed of a material other than resin, such as a metal gear, can be mixed, or the multi-stage gear device can be composed of only resin gears. In the present application, a gear device in which a resin gear and a gear meshing with the gear are metal gears is included.

[0056] Further, the grease composition for resin lubrication described later is applied to the bearing portion of the resin gear, and the meshing portion of the resin gear with a gear composed of resin or a material other than resin, particularly the meshing portion of the resin gear with a metal gear.

[0057] Figure 3 is a schematic view of a multi-stage gear device 201 provided in an actuator, Figure 3 (a) of FIG. 1 is a front view of the multi-stage gear device 201, Figure 3 (b) of FIG. 1 is a side view (including a partial cross section) of the multi-stage gear device 201. Note that in Figure 3 In (b) of FIG. 1, in addition to the multi-stage gear device 201, a motor 211 and an output shaft 211a thereof and an actuator output shaft 212 are also shown in the drawing.

[0058] Figure 3The illustrated multi-stage gear device 201 is provided with a first-stage gear 202 that is integrally rotatable with an output shaft 211a of a motor 211, a second-stage gear 203 that is engaged with the first-stage gear 202, and a third-stage gear 205 that is engaged with the second-stage gear 203. Further, in Figure 3 the second-stage gear 203, the shaft 204 of the third-stage gear 205 is illustrated in the drawing, and the output shaft 212 of the actuator described above is also illustrated in the drawing.

[0059] In the present embodiment, the grease composition for resin lubrication described later is applied to Figure 3 the engagement portions X of the first-stage gear 202 and the second-stage gear 203, the engagement portions Y of the second-stage gear 203 and the third-stage gear 205, the bearing portion 204a of the second-stage gear 203, and the bearing portion 206a of the third-stage gear 205.

[0060] In one embodiment, the first-stage gear 202 and the third-stage gear 205 in Figure 7 may be metal gears, and the second-stage gear 205 can be a resin gear.

[0061] In the multi-stage gear device 201 described above, the shafts that constitute the device, that is, the shafts (204, 206) of the multi-stage gear device, the output shaft 202a of the motor, and the output shaft 212 of the actuator can be either metal or resin, and can be configured as follows, for example.

[0062] For example, the output shaft 211a of the motor 211 is a rotating shaft made of metal. The output shaft 211a and the first-stage gear 202 are fixed, and the first-stage gear 202 rotates together with the output shaft 211a, and thus there is no bearing portion that rotates relatively between the first-stage gear 202 and the output shaft 211a.

[0063] On the other hand, the shaft 204 of the second-stage gear 203 and the shaft 206 of the third-stage gear 205 are both fixed shafts made of resin. Further, the second-stage gear 203 and the third-stage gear 205 rotate while sliding with respect to the respective fixed shafts. Thus, the grease composition for resin lubrication described later is applied not only to the engagement portions X and Y of the gears, but also to the bearing portion 204a between the second-stage gear 203 and the shaft 204 (fixed shaft) of the second-stage gear, and the bearing portion 206a between the third-stage gear 205 and the shaft 206 (fixed shaft) of the third-stage gear.

[0064] Note that, as the resin that can be used as a resin member that constitutes these gear devices (gears, shafts of gears), and actuators (output shafts of motors, base members, outer members (casing), output shafts of actuators, etc.) that have the gear devices, polyethylene (PE), polypropylene (PP), ABS resin (ABS), polyoxymethylene (POM), polyamide (PA), polycarbonate (PC), phenol resin (PF), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), polyether sulfone (PES), polyimide (PI), polyether ether ketone (PEEK), etc. can be exemplified.

[0065] Furthermore, in the metal members that constitute these gear devices, carbon steel, chromium steel, chromium-molybdenum alloy steel, stainless steel, etc. can be used.

[0066] The gear device of the present embodiment is preferably used for an actuator used in an air conditioning processing system for vehicles, etc. In the air conditioning processing system for vehicles, the use range is wide from -40°C to 100°C, and when used in these temperature cycles, dew condensation sometimes occurs inside the actuator, and water droplets are attached to the tooth surfaces and the lubricating grease.

[0067] Furthermore, the gear device of the present embodiment is also preferably used, for example, for an actuator used in an automatic opening / closing device of a toilet seat, toilet cover, etc. In the automatic opening / closing device of a toilet seat, etc., water sometimes splashes to the actuator at the time of cleaning, etc.

[0068] Even for a gear device used in such an environment where water easily comes into contact, by using the grease composition for resin lubrication of the present application, friction / wear is suppressed, and long life of the product is achieved.

[0069] [Grease composition for resin lubrication]

[0070] The grease composition for resin lubrication of the present application will be described.

[0071] <Base oil>

[0072] In the grease composition for resin lubrication of the present embodiment, a fluorine-based base oil and a synthetic hydrocarbon oil are used as the base oil.

[0073] As the fluorine-based base oil, for example, a fluorine-based base oil in which a perfluoropolyether (PFPE) is a main component can be exemplified. Note that the PFPE is a compound represented by the general formula: RfO(CF2O) p (C2F4O) q (C3F6O) r Rf (Rf: perfluoro lower alkyl group, p, q, r: integers).

[0074] It should be noted that perfluoropolyethers are roughly classified into linear types and side chain types, and the linear types have a smaller temperature dependence of kinematic viscosity than the side chain types. This means that the linear types have a lower viscosity at low temperature environments than the side chain types, and a higher viscosity at high temperature environments than the side chain types. In the case of use at high temperature environments, for example, it is desirable that the viscosity at high temperature environments be high, i.e., the linear types of perfluoropolyethers are preferably used, from the viewpoint of suppressing the outflow of the grease from the use site, and the resulting exhaustion.

[0075] It should be noted that the present inventors have studied the constitution of the optimum friction coefficient value that serves as an index of the lubricating properties, and as a result, have found that, in addition to the composition of the grease composition, the kinematic viscosity value of the fluorine-based base oil is one of the important factors.

[0076] As shown in the results of the examples described later, the following behavior was shown: in a grease composition containing a specific base oil, a thickening agent, an extreme pressure additive, and a fluorine-based surfactant, in the case where the kinematic viscosity value at 40°C of the fluorine-based base oil was varied (392 mm 2 / s (Example 5), 300 mm 2 / s (Example 8), 200 mm 2 / s (Comparative Example 5)), the dynamic friction coefficient value slowly increased as the kinematic viscosity value became lower. Also, it was confirmed that when the kinematic viscosity value was lower than 300 mm 2 / s, the dynamic friction coefficient value exceeded 0.060.

[0077] As shown by the above results, in the resin lubricating grease composition of the present application, the kinematic viscosity at 40°C of the above fluorine-based base oil is preferably 300 mm 2 / s or more, and the kinematic viscosity is particularly preferably 390 mm 2 / s or more.

[0078] As the above synthetic hydrocarbon oil, for example, n-paraffin, isoparaffin, polybutene, polyisobutene, 1-decene oligomer, co-oligomer of 1-decene and ethylene, and the like poly-alpha olefin (PAO) are preferable.

[0079] The mixing ratio of the fluorine-based base oil and the synthetic hydrocarbon oil is not particularly limited, and for example, with respect to the total amount of the base oils being 100 mass%, the fluorine-based base oil : synthetic hydrocarbon oil can be set to 99 to 5 mass% : 1 to 95 mass%, for example, 99 to 10 mass% : 1 to 90 mass%, 98 to 20 mass% : 2 to 80 mass%, 98 to 30 mass% : 2 to 70 mass%, 98 to 50 mass% : 2 to 50 mass%, preferably 98 to 65 mass% : 2 to 35 mass%, and particularly 98 to 70 mass% : 2 to 30 mass%, and the like.

[0080] Further, the ratio of the base oil as a whole, in which the fluorine-based base oil and the synthetic hydrocarbon oil are aggregated, with respect to the total mass of the grease composition of the present application can be set to 60 to 90 mass%, for example, 65 to 80 mass%, 65 to 75 mass%.

[0081] <Thickening agent>

[0082] In the grease composition of the present application, a fluorine-based thickening agent and a lithium soap thickening agent or a lithium complex soap thickening agent are added as a thickening agent.

[0083] <Fluorine-based thickening agent>

[0084] As the fluorine-based thickening agent, a fluororesin particle is preferable, and for example, a particle of polytetrafluoroethylene (PTFE) is preferably used. PTFE is a polymer of tetrafluoroethylene, and is represented by the general formula: [C2F4] n (n: degree of polymerization).

[0085] Further, as the fluorine-based thickening agent that can be used, for example, a perfluoroethylene propylene copolymer (FEP), an ethylene tetrafluoroethylene copolymer (ETFE), and a tetrafluoroethylene perfluoroalkyl vinyl ether copolymer (PFA) can be listed.

[0086] The size of the PTFE particle is not particularly limited, and for example, polytetrafluoroethylene having an average particle diameter of 0.1 to 100 μm can be used. Further, the shape of the PTFE particle is not particularly limited, and can be spherical, polyhedral, acicular, or the like.

[0087] The fluorine-based thickening agent described above is used in an amount of 1 to 40 mass%, for example, 10 to 30 mass%, 20 to 30 mass%, with respect to the total mass of the grease composition.

[0088] <Lithium soap thickening agent / lithium complex soap thickening agent>

[0089] In the present application, a lithium soap thickening agent is used in addition to the fluorine-based thickening agent described above.

[0090] As the above lithium soap thickener, a lithium salt of an aliphatic monocarboxylic acid can be used.

[0091] The above aliphatic carboxylic acid can be any of a straight chain, a branched chain, saturated, or unsaturated, and generally a fatty acid having a carbon atom number of about 2 to 30, for example, a carbon atom number of 12 to 24 can be used. Specifically, saturated fatty acids such as butyric acid, caproic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, and behenic acid, and unsaturated fatty acids such as oleic acid, linoleic acid, linolenic acid, and ricinoleic acid can be listed.

[0092] Among them, as the above lithium soap thickener, lithium salts of stearic acid, lauric acid, and ricinoleic acid, and lithium salts of compounds in which the above acids are substituted with a hydroxyl group can be listed as representative examples.

[0093] Note that in the present application, a lithium complex soap thickener can be used instead of the lithium soap thickener.

[0094] The lithium complex soap thickener improves heat resistance compared to the lithium soap thickener by combining a higher fatty acid with a dibasic acid or an inorganic acid (boric acid, etc.).

[0095] The lithium complex soap thickener can be obtained, for example, by reacting lithium hydroxide with an aliphatic monocarboxylic acid having a carbon atom number of 12 to 24 and an aliphatic dicarboxylic acid having a carbon atom number of 2 to 12, which contains at least one hydroxyl group.

[0096] As the above aliphatic monocarboxylic acid having a carbon atom number of 12 to 24 and containing at least one hydroxyl group, for example, hydroxyl lauric acid, hydroxyl palmitic acid, hydroxyl stearic acid, hydroxyl oleic acid, hydroxyl arachidic acid, hydroxyl behenic acid, and hydroxyl lignoceric acid can be listed.

[0097] Further, as the aliphatic dicarboxylic acid having a carbon atom number of 2 to 12, for example, oxalic acid, malonic acid, succinic acid, methylsuccinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, nonamethylene dicarboxylic acid, and decamethylene dicarboxylic acid can be listed.

[0098] These monocarboxylic acid and dicarboxylic acid can be used alone or two or more kinds can be used in combination.

[0099] For example, as the above lithium complex soap thickener, as a representative example, a substance obtained by reacting lithium hydroxide with hydroxyl stearic acid and azelaic acid in combination can be listed.

[0100] The above lithium soap thickener or lithium complex soap thickener is used at 0.1 to 15 mass%, for example, 0.2 to 5 mass% with respect to the total mass of the grease composition.

[0101] It should be noted that the total amount of fluorinated thickener and lithium soap thickener or lithium complex soap thickener (total amount of thickener) can be formulated relative to the total mass of the resin lubricating grease composition in a manner that is 5 to 40% by mass, for example 10 to 30% by mass, preferably 15 to 30% by mass, and particularly 20 to 30% by mass.

[0102] Furthermore, in this invention, when the total mass of the fluorinated base oil, synthetic hydrocarbon oil, fluorinated thickener, and lithium soap thickener or lithium complex soap thickener is set to 100, the mass ratio of the total amount of fluorinated base oil and fluorinated thickener [A] to the total amount of synthetic hydrocarbon oil and lithium soap thickener or lithium complex soap thickener [B] can be set, for example, as [A]∶[B]=99~60∶1~40, such as [A]∶[B]=98~70∶2~30, [A]∶[B]=98~75∶2~25, [A]∶[B]=98~80∶2~20, [A]∶[B]=98~85∶2~15, [A]∶[B]=98~90∶2~10.

[0103] <Fluoro-based surfactants>

[0104] The resin-lubricating grease of the present invention contains a fluorinated surfactant.

[0105] Examples of fluorinated surfactants include: fluorinated sulfonates, fluorinated sulfates, fluorinated phosphates, fluorinated alkyl sulfonic acids, and fluorinated alkyl carboxylic acids. For example, fluorinated phosphates can be used.

[0106] The inventors studied the composition of the optimal coefficient of friction, particularly the optimal coefficient of friction between resin and metal, to meet the indicators of lubrication properties. They found that, in addition to the composition of the grease composition, the formulation of fluorinated surfactants is also crucial, and the amount of surfactants used is also an important factor.

[0107] As an example, the results of friction and wear tests (metal-resin interaction) of grease compositions containing specific base oils, thickeners, and extreme pressure additives, with varying amounts of fluorinated surfactants (0–3% by mass), are shown below. Figure 7 .

[0108] like Figure 4 As shown, it was confirmed that although the coefficient of kinetic friction between the metal and resin was slightly higher than 0.060 (i.e., 0.061) without the addition of a fluorinated surfactant, the coefficient of kinetic friction decreased with the addition of a fluorinated surfactant. However, it was confirmed that when the amount of fluorinated surfactant reached 3% by mass, the coefficient of kinetic friction increased sharply, becoming a higher value (0.071) than without the surfactant.

[0109] Thus, the above-mentioned fluorine-based surfactant can be used in an amount of 0.1 to 2.5% by mass, preferably 0.5 to 2.5% by mass, for example, 1 to 2% by mass, relative to the total mass of the grease composition.

[0110] <Extreme pressure additive>

[0111] The grease for resin lubrication of the present application contains an extreme pressure additive (extreme pressure agent).

[0112] The extreme pressure additive is known to have a function of reducing friction, wear, and seizure of a metal surface by forming a lubricating film by reacting with the metal surface. Therefore, it is considered that the grease for resin lubrication with the extreme pressure additive incorporated therein does not have any effect on a sliding surface made of resin, but the present inventors have found that the coefficient of friction is reduced when it is applied to a resin sliding surface even in the case where the extreme pressure additive is incorporated.

[0113] As the above-mentioned extreme pressure additive, for example, phosphorus-based compounds, sulfur-based compounds, chlorine-based compounds, metal salts of sulfur-based compounds, high molecular weight esters, and the like can be listed.

[0114] Among them, in the present application, at least one of phosphorus-based compounds (phosphorus-based additives) and high molecular weight esters (high molecular weight ester-based additives) is preferably used as the extreme pressure additive, and they can be used in various combinations.

[0115] As the above-mentioned phosphorus-based additives, phosphoric acid esters, phosphorous acid esters, amine salts of phosphoric acid esters, thiophosphoric acid esters, and the like can be listed.

[0116] As the preferred phosphorus-based additives, for example, tricresyl phosphate (TCP), triphenyl phosphate, tributyl phosphate, trioctyl phosphate, trioleyl phosphate, and the like can be listed as triesters of phosphoric acid, and triphenyl thiophosphate (TPPS) and the like can be listed as triesters of thiophosphoric acid, and they can be obtained as commercially available products.

[0117] Further, as the above-mentioned high molecular weight esters, for example, esters of aliphatic mono- and di-carboxylic acids and polyhydric alcohols can be listed. As specific examples of the above-mentioned high molecular weight esters, for example, the series of PERFAD (registered trademark) and the series of PRIOLUBE (registered trademark) manufactured by CRODA Japan Co., Ltd. can be listed, but are not limited thereto.

[0118] The above-mentioned extreme pressure additive can be used in an amount of 0.005 to 10% by mass, preferably 0.01 to 5% by mass, for example, 0.01 to 1% by mass, relative to the total mass of the grease composition.

[0119] <Other additives>

[0120] Further, in the grease composition for resin lubrication, in addition to the essential components described above, an additive generally used in a grease composition as needed can be contained within a range not impairing the effects of the present application.

[0121] As examples of such an additive, an antioxidant, a metal deactivator, an antirust agent, an oiliness improver, a viscosity index improver, a tackifier, and the like can be listed.

[0122] In the case where these other additives are contained, the amount of addition (total amount) is usually 0.1 to 10 mass% relative to the total mass of the grease composition.

[0123] As the antioxidant described above, for example, hindered phenol-based antioxidants such as octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, pentaerythritol tetra[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2,4-bis-(n-octylthio)-6-(4-hydroxy-3,5-di-tert-butylanilino)-1,3,5-triazine, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, triethylene glycol-bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2,2-thio-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxy-hydrocinnamamide), and the like; phenol-based antioxidants such as 2,6-di-tert-butyl-4-methylphenol and 4,4-methylenebis(2,6-di-tert-butylphenol); amine-based antioxidants such as triphenylamine, phenyl-a-naphthylamine, alkylated phenyl-a-naphthylamine, phenothiazine, alkylated phenothiazine, and the like; and the like can be listed.

[0124] As the metal deactivator, benzotriazole, sodium nitrite, and the like can be listed.

[0125] The grease composition for resin lubrication of the present application can be obtained by mixing the various base oils described above, the various thickening agents, the fluorine-based surfactant, and the extreme pressure additive in prescribed proportions, and incorporating other additives as desired.

[0126] Further, a resin lubricating grease composition can also be obtained by compounding a fluorine-based grease composed of a fluorine-based base oil and a fluorine-based thickener, a lithium soap grease (or lithium complex soap grease) composed of a synthetic hydrocarbon oil and a lithium soap thickener (or lithium complex soap thickener) from among the two base greases, a fluorine-based surfactant, an extreme pressure additive, and other additives as desired. Alternatively, a resin lubricating grease composition can also be produced by compounding one of the base greases with the remaining base oil, thickener, fluorine-based surfactant, and extreme pressure additive, and other additives as desired.

[0127] Generally, the content of the thickener with respect to the base grease is about 10 to 30 mass%, and, for example, in the above two base greases, the content of each thickener with respect to each base grease can be set to 15 to 30 mass% for the fluorine-based thickener, and 10 to 20 mass% for the lithium soap or lithium complex soap thickener.

[0128] Further, the compounding ratio (mass ratio, total 100) of the above two base greases can be set to, for example, fluorine-based grease : lithium soap grease or lithium complex soap grease = 99 to 60 : 1 to 40, for example, 98 to 70 : 2 to 30, 98 to 75 : 2 to 25, 98 to 80 : 2 to 20, 98 to 85 : 2 to 15, 98 to 90 : 2 to 10.

[0129] The resin lubricating grease composition of the present application is a relatively soft grease, for example, the mixed consistency can be set to a range of 265 to 340, since it is used for a sliding surface made of resin.

[0130] The present application is not limited to the embodiments, specific examples described in the present specification, and various modifications, alterations can be made within the scope of the technical idea recited in the claims.

[0131] [Examples]

[0132] Hereinafter, the present application will be further described in detail using examples. However, the present application is not limited thereto.

[0133] [Evaluation of the resin lubricating grease composition]

[0134] The grease compositions used in Examples 1 to 12 and Comparative Examples 1 to 10 were prepared in compounding amounts shown in the following tables.

[0135] Note that the details of each component used in the preparation of the grease and its abbreviations are described below.

[0136] (a) Base oil

[0137] (a1) Fluorine-based base oil: Straight-chain perfluoropolyether (PFPE) oil.

[0138] (a1-1) Straight-chain PFPE oil 1 (Kinematic viscosity at 40°C: 392 mm 2 / s).

[0139] (a1-2) Straight-chain PFPE oil 2 (Kinematic viscosity at 40°C: 300 mm 2 / s).

[0140] (a1-3) Straight-chain PFPE oil 3 (Kinematic viscosity at 40°C: 200 mm 2 / s).

[0141] (a2) Synthetic hydrocarbon oil: Poly-α-olefin (PAO).

[0142] (a2-1) PAO 1 (Kinematic viscosity at 40°C: 30 mm 2 / s).

[0143] (a2-2) PAO 2 (Kinematic viscosity at 40°C: 100 mm 2 / s).

[0144] (a2-3) PAO 3 (Kinematic viscosity at 40°C: 200 mm 2 / s).

[0145] (a2-4) PAO 4 (Kinematic viscosity at 40°C: 18 mm 2 / s).

[0146] (a2-5) PAO 5 (Kinematic viscosity at 40°C: 300 mm 2 / s).

[0147] (b) Thickening agent

[0148] (b1) Fluorine-based thickening agent: PTFE (Polytetrafluoroethylene) resin (Particle diameter 1000 nm).

[0149] (b2) Li soap thickening agent: 120H Li soap (12-hydroxy stearic acid lithium).

[0150] (c) Additive

[0151] (c1) Fluorine-based surfactant: Fluorine-containing phosphoric acid ester, product name "MEGAFACE F-510".

[0152] (c2) Extreme pressure additive: Tricresyl phosphate (TCP: Tricresyl Phosphate), product name "Tritolyl Phosphate", manufactured by FUJI FILM and Meiji Pure Chemical Co., Ltd.

[0153] (c3) Antioxidant: Diarylamine-based antioxidant, product name "IRGANOX L57", BASF Japan KK.

[0154] As to the properties of the obtained grease compositions, the lubricating properties between metal and resin (friction and wear properties (1)) and the lubricating properties between resins (resin pin and resin film) (friction and wear test (2)) were evaluated in the following procedures.

[0155] < Test Method >

[0156] 1. Evaluation of lubricating properties between metal and resin: Friction and wear test (1) Coefficient of kinetic friction

[0157] As shown in the conceptual diagram of the friction and wear test shown in Figure 5 , a laminated test sample was prepared by applying each of the grease compositions on a flat plate (cold-rolled steel plate). The probe (resin pin) was made to slide on the surface of the flat plate (cold-rolled steel plate) of the laminated test sample at a prescribed load, and the coefficient of kinetic friction when the probe moved at a constant speed was measured. The measurement was performed during a sliding cycle of 5 strokes, and the average of the values obtained was taken as the coefficient of kinetic friction in each measurement.

[0158] The lubricating properties were evaluated with respect to the coefficient of kinetic friction of each of the grease compositions of the examples and comparative examples, which were each tested three times, with the average of the three times taken as the coefficient of kinetic friction of each of the grease compositions, with reference to the evaluation criteria shown below.

[0159] < Test Conditions >

[0160] • Measuring device: Load variation type friction and wear test system HHS2000 manufactured by Shinto Scientific Co., Ltd.

[0161] • Measurement conditions: Test in air.

[0162] • Probe: Resin pin (pin diameter: 2.5 mm, pin type: PPA resin).

[0163] • Feed scale: 10 mm.

[0164] • Load: 50 g.

[0165] • Sliding speed: 0.5 mm / sec.

[0166] • Sliding cycle: 5 strokes.

[0167] < Evaluation Criteria >

[0168] Under the test conditions of the present examples, the lower the coefficient of kinetic friction, the more excellent the lubricating properties.

[0169] It should be noted that if the coefficient of kinetic friction exceeds 0.060, the click operation in the actual machine will deteriorate, so it is preferable to be below 0.060.

[0170] A (Preferred): The coefficient of kinetic friction is below 0.060.

[0171] N (not preferred): The coefficient of kinetic friction exceeds 0.060.

[0172] 2. Evaluation of lubrication characteristics between resins: Friction and wear test (2) Static friction coefficient

[0173] like Figure 6 The conceptual diagram of the friction and wear test illustrates a process where a nylon sheet is placed on a flat plate, and various grease compositions are coated onto the nylon sheet to create a stacked specimen. This stacked specimen is then immersed in water. While immersed, a probe (resin pin) is slid across the surface of the nylon sheet of the stacked specimen under a specified load, and the coefficient of friction is measured. Measurements are performed over 200 sliding cycles, and the maximum value obtained is taken as the static coefficient of friction for each measurement (the highest coefficient of friction corresponds to the static coefficient of friction at the instant the probe begins to move or at the instant it comes to rest).

[0174] Each of the grease compositions in the embodiments and comparative examples was tested three times, and the average value of the three tests was used as the static friction coefficient of each grease composition. The lubrication characteristics were evaluated against the evaluation criteria shown below.

[0175] <Experimental Conditions>

[0176] • Measuring device: HHS2000 load variation type friction and wear testing system manufactured by Shin-Dong Science Co., Ltd.

[0177] • Test conditions: Tested in water.

[0178] • Probe: Resin pin (pin diameter: 2.5mm, pin type: PPA resin).

[0179] • Feed specification: 3mm.

[0180] • Load capacity: 1000g.

[0181] • Sliding speed: 1.0 mm / second.

[0182] • Sliding cycle: 200 strokes.

[0183] <Evaluation Criteria>

[0184] Under the test conditions of this embodiment, the lower the static friction coefficient, the better the lubrication characteristics.

[0185] Note that, when the static friction coefficient value exceeds 0.120, the waterproof film is broken in the switch actual machine, and thus it is preferable that the static friction coefficient be 0.120 or less.

[0186] A (preferable): Static friction coefficient is 0.120 or less.

[0187] N (not preferable): Static friction coefficient exceeds 0.120.

[0188] The results are shown in Tables 1 and 2. Note that, in the table, the compounding amount: mass% is a value with respect to the total mass of the composition (in which, due to rounding off to the third decimal place, sometimes the total is not 100 mass%). Note that, in the table, the fluorine-based base oil and the fluorine-based thickener are collectively referred to as "fluorine-based grease", and the synthetic hydrocarbon oil and the lithium soap thickener are collectively referred to as "Li soap grease".

[0189] Further, in Figure 6 , a microscope photograph of the grease composition of Comparative Example 2 Figure 6 (A) and Example 2 Figure 7 (B) is shown, and in Figure 8 , the dynamic friction coefficient values of the grease compositions of Comparative Example 2, Example 6, Example 5, Example 2, Example 7, and Comparative Example 6 are shown with respect to the compounding amount (0 mass% to 3 mass%) of the fluorine-based surfactant.

[0190] In Figure 9 , the dynamic friction coefficient values of the grease composition in which the addition amount of the fluorine-based surfactant is 2 mass% (O: Comparative Example 9, Examples 1 to 4, Comparative Example 10) and the grease composition in which the addition amount of the fluorine-based surfactant is 0 mass% (■: Comparative Example 7, Comparative Examples 1 to 4) are shown with respect to the "fluorine-based grease content" (100 mass% to 70 mass%) referred to in the figure, in which the "fluorine-based grease content" refers to the proportion of the total amount of the fluorine-based base oil and the fluorine-based thickener when the total mass of the fluorine-based base oil, the synthetic hydrocarbon oil, the fluorine-based thickener, and the lithium soap thickener is taken as 100.

[0191] Further, in Figure 6 , the static friction coefficient values of the grease compositions of Comparative Example 9, Examples 1 to 4, and Comparative Example 10 are shown with respect to the "fluorine-based grease content" (100 mass% to 70 mass%) referred to in the figure, in which the "fluorine-based grease content" refers to the proportion of the total amount of the fluorine-based base oil and the fluorine-based thickener when the total mass of the fluorine-based base oil, the synthetic hydrocarbon oil, the fluorine-based thickener, and the lithium soap thickener is taken as 100.

[0192] [Table 1]

[0193]

[0194] Note: *1 The value in parentheses indicates kinematic viscosity at 40°C

[0195] *2 A (preferable): dynamic friction coefficient is 0.060 or less N (not preferable): dynamic friction coefficient exceeds 0.060

[0196] *3 A (preferable): static friction coefficient is 0.120 or less N (not preferable): static friction coefficient exceeds 0.120

[0197] [Table 2]

[0198]

[0199] Note: *1 The value in parentheses indicates kinematic viscosity at 40°C

[0200] *2 A (preferable): dynamic friction coefficient is 0.060 or less N (not preferable): dynamic friction coefficient exceeds 0.060

[0201] *3 A (preferable): static friction coefficient is 0.120 or less N (not preferable): static friction coefficient exceeds 0.120

[0202] Figure 6 is a microscopic observation photograph of the grease composition of Comparative Example 2 (A) and Example 2 (B). As shown in Figure 6 , in the grease composition not incorporating a surfactant (A) of Comparative Example 2, compared to the grease composition incorporating a surfactant (B) of Example 2, many agglomerates of about 20 to 30 μm or so were confirmed. It is considered that the presence of the agglomerates resulted in an increase in the friction coefficient (dynamic friction coefficient, static friction coefficient) on the sliding surface. Figure 6 Figure 6 Figure 6 is the result of the friction and wear test of the grease composition (Comparative Example 2, Example 6, Example 5, Example 2, Example 7, Comparative Example 6) in which the incorporation amount of the fluorine-based surfactant was changed within 0 mass% to 3 mass% (dynamic friction coefficient value). Figure 7

[0203] Figure 7 is the result of the friction and wear test of the grease composition (Comparative Example 2, Example 6, Example 5, Example 2, Example 7, Comparative Example 6) in which the incorporation amount of the fluorine-based surfactant was changed within 0 mass% to 3 mass% (dynamic friction coefficient value).

[0204] Figure 7 The horizontal axis of the graph shown in Figure 7 indicates the incorporation amount of the fluorine-based surfactant in the grease composition (mass%), and the vertical axis indicates the measured dynamic friction coefficient value. Note that in

[0205] As shown in Figure 8 ​​​As shown in the graph, it was confirmed that while the dynamic friction coefficient value slightly exceeded 0.060 (i.e., 0.061) in the case where the fluorine-based surfactant was not incorporated, the dynamic friction coefficient value decreased by incorporating the fluorine-based surfactant, and the value was lower than 0.060. However, it was confirmed that when the incorporation amount of the fluorine-based surfactant reached 3% by mass, the dynamic friction coefficient value sharply increased to a value (0.071) higher than in the case where the surfactant was not incorporated.

[0206] Figure 8 is the result (dynamic friction coefficient value) of the friction and wear test in the grease composition in which the addition amount of the fluorine-based surfactant was 2% by mass (O: Comparative Example 9, Examples 1 to 4, Comparative Example 10) and the grease composition in which the addition amount of the fluorine-based surfactant was 0% by mass (■: Comparative Example 7, Comparative Examples 1 to 4), when the "fluorine-based grease content" referred to in the graph was changed within a range of 100% by mass to 70% by mass, and the "fluorine-based grease content" refers to the proportion of the total amount of the fluorine-based base oil and the fluorine-based thickener, when the total mass of the fluorine-based base oil, the synthetic hydrocarbon oil, the fluorine-based thickener, and the lithium soap thickener is set to 100.

[0207] Figure 8 The horizontal axis of the graph shown is the proportion (mass %) of the total amount of the fluorine-based base oil and the fluorine-based thickener, when the total mass of the fluorine-based base oil, the synthetic hydrocarbon oil, the fluorine-based thickener, and the lithium soap thickener is set to 100, and the vertical axis is the dynamic friction coefficient value measured. Note that in the graph shown in Figure 8 , the broken line marked in parallel with the horizontal axis indicates the dynamic friction coefficient value: 0.060.

[0208] As shown in Figure 9 , both when the addition amount of the fluorine-based surfactant was 2% by mass (indicated by O in the graph) and when the addition amount was 0% (indicated by ■ in the graph), the following tendency was observed: as the proportion of the total amount of the fluorine-based base oil and the fluorine-based thickener decreased, the dynamic friction coefficient value increased.

[0209] When the addition amount of the fluorine-based surfactant was 2% by mass (O), the dynamic friction coefficient between the resin and the metal became a value lower than 0.060, when the proportion of the total amount of the fluorine-based base oil and the fluorine-based thickener was within a range of 100% by mass (i.e., in the case where the synthetic hydrocarbon oil and the lithium soap thickener were not incorporated) to 75% by mass. On the other hand, when the addition amount of the fluorine-based surfactant was 0% by mass (■), in the case where the proportion of the total amount of the fluorine-based base oil and the fluorine-based thickener was set to 100% by mass, although the dynamic friction coefficient was lower than 0.060, by incorporating the synthetic hydrocarbon oil and the lithium soap thickener, the dynamic friction coefficient value became a value higher than 0.060.

[0210] Figure 9is the result (static friction coefficient value) of the friction and wear test of the lubricating grease composition in the lubricating grease composition (Comparative Example 9, Examples 1 to 4, Comparative Example 10) in which the "fluorine-based grease content" referred to in the graph is changed within 100 mass% to 70 mass%, wherein the "fluorine-based grease content" refers to the proportion of the total amount of the fluorine-based base oil and the fluorine-based thickener when the total mass of the fluorine-based base oil, the synthetic hydrocarbon oil, the fluorine-based thickener, and the lithium soap thickener is set to 100.

[0211] Figure 9 The horizontal axis of the graph shown is the proportion (mass%) of the total amount of the fluorine-based base oil and the fluorine-based thickener when the total mass of the fluorine-based base oil, the synthetic hydrocarbon oil, the fluorine-based thickener, and the lithium soap thickener is set to 100, and the vertical axis is the measured static friction coefficient value. Note that, in the graph, Figure 9 the dotted line parallel to the horizontal axis indicates a static friction coefficient value of 0.120.

[0212] As shown in ​ , when the proportion of the total amount of the fluorine-based base oil and the fluorine-based thickener is set to 100 mass% (i.e., when the synthetic hydrocarbon oil and the lithium soap thickener are not compounded), the static friction coefficient between resins becomes a result exceeding 0.120. It was confirmed that by compounding the synthetic hydrocarbon oil and the lithium soap thickener thereto, the static friction coefficient value sharply decreases and the static friction coefficient becomes lower than 0.120. However, when the compounding amount of the synthetic hydrocarbon oil and the lithium soap thickener is increased and the proportion of the total amount of the fluorine-based base oil and the fluorine-based thickener becomes 70 mass%, the static friction coefficient value again becomes a result higher than 0.120.

[0213] As shown in Table 1, it was confirmed that the lubricating grease compositions of Examples 1 to 12 all became a result in which the kinetic friction coefficient was 0.060 or less and the static friction coefficient was 0.120 or less, and the lubricating properties between metals and resins and the lubricating properties between resins were both excellent.

[0214] Further, as shown in Example 5 and Example 8, by using a fluorine-based base oil in the range of 300 mm 2 / s or more at 40°C, a result in which the lubricating properties were excellent could be obtained, and by using a fluorine-based base oil in which the kinematic viscosity was 390 mm 2 / s or more (Example 5), a result in which the lubricating properties were more excellent could be obtained.

[0215] Furthermore, as shown in Example 2, Examples 5 to 7, when the compounding proportion of the fluorine-based surfactant was changed in the range of 0.5 mass% to 2.5 mass%, a result in which the lubricating properties were excellent could be obtained.

[0216] Also, as shown in Examples 1 to 4, in the case where the mass ratio of the total amount [A] of the fluorine-based base oil (al) and the fluorine-based thickener (bl) to the total amount [B] of the synthetic hydrocarbon oil (a2) + lithium soap thickener (b2) is changed within the range of [A] : [B] = 98 : 2 to 75 : 25, excellent results in lubricating properties can be obtained.

[0217] Note that, as shown in Examples 5, 8 to 12, in the case where the kinematic viscosity at 40°C of the synthetic hydrocarbon oil is changed within the range of 18 to 200 mm 2 / s, excellent results in lubricating properties can be obtained.

[0218] On the other hand, as shown in Table 2, the grease compositions of Comparative Examples 1 to 4, which do not contain a fluorine-based surfactant, have low static friction coefficients (0.109 or less), but have deteriorated dynamic friction coefficients (0.061 to 0.105), resulting in poor lubricating properties between the metal and the resin compared with the grease compositions of the Examples. The dynamic friction coefficients of the grease compositions of Examples 1 to 4 are 0.060 or less (0.031 to 0.056), and in this result, the dynamic friction coefficient is reduced by about 3 to 5 times or so by incorporating the fluorine-based surfactant.

[0219] Further, in the grease composition of Comparative Example 5, which uses a fluorine-based base oil having a kinematic viscosity at 40°C of less than 300 mm 2 / s (kinematic viscosity: 200 mm 2 / s), the dynamic friction coefficient is also deteriorated (0.067), resulting in poor lubricating properties between the metal and the resin compared with the grease compositions of the Examples.

[0220] On the other hand, the grease compositions of Comparative Examples 7 to 9, which use only a fluorine-based base oil and a fluorine-based thickener, and do not use a synthetic hydrocarbon oil and a lithium soap thickener or a lithium complex soap thickener, and an extreme pressure additive, have deteriorated static friction coefficients (0.124 or more).

[0221] Further, the grease composition of Comparative Example 6, in which the amount of the fluorine-based surfactant incorporated is set to 3.0 mass%, compared with the grease composition of Example 2, in which the amount of the fluorine-based surfactant incorporated is 2.0 mass%, has a significantly deteriorated dynamic friction coefficient (Example 2: 0.042, Comparative Example 6: 0.071), resulting in deteriorated lubricating properties between the metal and the resin.

[0222] Moreover, the grease composition of Comparative Example 10 in which the mass ratio of the total amount [A] of the fluorine-based base oil (al) and the fluorine-based thickener (bl) to the total amount [B] of the synthetic hydrocarbon oil (a2) + the lithium soap thickener (b2) is set to [A] : [B] = 70 : 30 was compared with the grease composition of Example 4 in which the mass ratio is set to [A] : [B] = 75 : 25, and it was confirmed that the dynamic friction coefficient (Example 4: 0.056, Comparative Example 10: 0.067) and the static friction coefficient (Example 4: 0.117, Comparative Example 10: 0.122) were both increased, and the lubricating properties between the metal and the resin and between the resins were both decreased.

[0223] According to the results of the above comparative examples, it was confirmed that, in order to satisfy the lubricating properties between the metal and the resin and between the resins in the object of the present application, it is more preferable that the combined amount of the fluorine-based surfactant is set to 3.0 mass% or less, and the mass ratio of the total amount [A] of the fluorine-based base oil (al) and the fluorine-based thickener (bl) to the total amount [B] of the synthetic hydrocarbon oil (a2) + the lithium soap thickener (b2) is set to [A] : [B] = 98 : 2 to 75 : 25.

[0224] As described above, it was confirmed that the grease composition for resin lubrication of the present application containing the fluorine-based base oil and the synthetic hydrocarbon oil, the fluorine-based thickener and the lithium soap thickener, and the extreme pressure additive is excellent in the lubricating properties for the resin sliding surface, and particularly excellent in the lubricating properties regardless of whether the counter surface is made of resin or metal, and it was found that the resin sliding member and the resin / metal inter-sliding member which are capable of suppressing the friction / wear by using the grease composition and capable of achieving long life are provided.

[0225] The above-described preferred embodiments have been described in detail, but the present application is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope capable of achieving the object of the present application are also included in the present application.

Claims

1. A grease composition for resin lubrication for a sliding surface made of resin, the grease composition for resin lubrication containing: a fluorine-based base oil and a synthetic hydrocarbon oil, a fluorine-based thickener, and a lithium soap thickener or a lithium complex soap thickener, a fluorine-based surfactant, and an extreme pressure additive, the fluorine-based surfactant being compounded at 0.5 to 2.5% by mass with respect to the total mass of the grease composition for resin lubrication, when the total mass of the fluorine-based base oil, the synthetic hydrocarbon oil, the fluorine-based thickener, and the lithium soap thickener or the lithium complex soap thickener is taken as 100, the mass ratio of the total amount [A] of the fluorine-based base oil and the fluorine-based thickener to the total amount [B] of the synthetic hydrocarbon oil and the lithium soap thickener or the lithium complex soap thickener is [A] : [B] = 75 : 25 to 98 :

2.

2. The grease composition for resin lubrication according to claim 1, wherein the fluorine-based surfactant is a fluorine-containing phosphate ester.

3. The grease composition for resin lubrication according to claim 1, wherein at least a part of the opposite surface to the sliding surface made of resin is a metal surface.

4. The grease composition for resin lubrication according to claim 1, wherein the sliding surface made of resin is a sliding surface of a sliding switch.

5. The grease composition for resin lubrication according to claim 1, wherein the extreme pressure additive is compounded at 0.01 to 5% by mass with respect to the total mass of the grease composition for resin lubrication. The fluorine-based base oil has a kinematic viscosity at 40°C of 300 mm 2 / s or more, 6. The grease composition for resin lubrication according to claim 1, wherein the fluorine-based base oil contains a straight-chain perfluoropolyether.

7. The grease composition for resin lubrication according to claim 1, wherein the synthetic hydrocarbon oil contains a polyalphaolefin (PAO).

8. The grease composition for resin lubrication according to claim 1, wherein the fluorine-based thickener is a fluororesin particle.

9. The grease composition for resin lubrication according to claim 1, wherein the lithium soap thickener or the lithium complex soap thickener is compounded at 0.1 to 15% by mass with respect to the total mass of the grease composition for resin lubrication.

10. The grease composition for resin lubrication according to claim 1, wherein the fluorine-based thickener and the lithium soap thickener or the lithium complex soap thickener are compounded at 15 to 30% by mass with respect to the total mass of the grease composition for resin lubrication.

11. The grease composition for resin lubrication according to claim 1, wherein the sliding surface made of resin is a sliding surface of a sliding switch.

12. The grease composition for resin lubrication according to claim 1, wherein the ratio of the fluorine-based base oil to the synthetic hydrocarbon oil is 98 to 65 mass% : 2 to 35 mass% when the total amount of the fluorine-based base oil and the synthetic hydrocarbon oil is taken as 100% by mass.

13. A resin sliding member having a sliding surface made of resin using the grease composition for resin lubrication according to any one of claims 1 to 12. The fluorine-based base oil has a kinematic viscosity at 40°C of 390 mm 2 / s or more.

14. The resin sliding member according to claim 13, wherein the resin sliding member is a sliding switch.

15. The resin sliding member according to claim 13, wherein the resin sliding member is a gear device. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The synthetic hydrocarbon oil has a kinematic viscosity at 40°C of 18 to 200 mm 2 / s. ​ ​ ​ ​ ​ ​ ​ 16. A resin / metal inter-sliding member having: a sliding surface of resin using the grease composition for resin lubrication according to any one of claims 1 to 12, and a counter surface of metal opposite to the sliding surface.

17. The resin / metal inter-sliding member according to claim 16, wherein the resin / metal inter-sliding member is a sliding switch.

18. The resin / metal inter-sliding member according to claim 16, wherein the resin / metal inter-sliding member is a gear device.

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