Grease composition for lubrication between metal and resin

Abstract

To provide a grease composition, a resin sliding member, and a sliding member between a resin and a metal, wherein the grease composition has excellent lubricity between the resin and the metal, and the resin sliding member and the sliding member between the resin and the metal can suppress friction and wear and can improve operability of products, and can achieve longer product life by applying the grease composition.SOLUTION: A grease composition G for resin lubrication applied to a resin sliding surfaces comprises: a fluorinated base oil (kinematic viscosity at 40°C of 300 mm2 / s or more) and a synthetic hydrocarbon oil as a base oil; a fluorinated thickener and a lithium soap thickener or a lithium composite soap thickener as a thickener; a fluoro-based surfactant as an additive; and an extreme pressure additive, wherein the resin sliding member (slide switch 101) has a resin sliding surface to which the grease composition G is applied.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a grease composition for resin lubrication, and in particular to a grease composition for resin lubrication between metal and resin. [Background technology]

[0002] Patent Document 1 proposes a slide switch (a resin sliding member) that aims to improve waterproofing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-139589 A Summary of the Invention [Problem to be solved by the invention]

[0004] When a sliding member having a resin sliding surface (hereinafter referred to as a resin sliding surface) is used in an environment where contact with water is likely, the grease composition applied to the sliding surface tends to be easily removed from the sliding surface. If the grease composition is removed from the resin sliding surface, it may cause a sudden increase in frictional force and an increase in the amount of wear on the sliding surface, which may result in adverse effects such as a shortened lifespan of the product equipped with the resin sliding surface. For this reason, a grease that can suppress friction and wear without being removed from the sliding surface even when a resin sliding member is used in an environment where contact with water is likely to occur, for example, in an underwater environment, is desired. Furthermore, in recent years, in the resin sliding components described above, sliding components in which the opposing surface facing the resin sliding surface is metal (i.e., resin-metal sliding components) are used, and there is a demand for greases that can suppress the friction and wear of the resin sliding surface, just as in sliding components in which the opposing surface facing the resin sliding surface is resin.

[0005] The present invention aims to provide a grease composition that has excellent lubricity between resin and metal, and to provide a resin sliding member and a resin-metal sliding member that can suppress friction and wear by applying the grease composition, thereby improving the operability of the product and extending its life. [Means for solving the problem]

[0006] One aspect of the present invention is a grease composition for resin lubrication to be applied to a resin sliding surface, comprising a fluorine-based base oil and a synthetic hydrocarbon oil, A fluorine-based thickener, a lithium soap thickener or a lithium complex soap thickener, A fluorosurfactant, and an extreme pressure additive, The fluorine-based base oil has a kinetic viscosity of 300 mm at 40°C. 2 / s or more, A grease composition for resin lubrication. The present invention also relates to a resin sliding member having a resin sliding surface to which the grease composition for resin lubrication is applied. The present invention further relates to a resin-metal sliding member having a resin sliding surface to which the grease composition for resin lubrication is applied and a metal mating surface facing the sliding surface. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram illustrating the structure of one embodiment of a sliding member (slide switch) of the present invention, in which FIG. 1(a) is a cross-sectional front view of a slide switch in an off state, and FIG. 1(b) is a cross-sectional front view of a slide switch in an on state. [Diagram 2] FIG. 2 is a schematic diagram illustrating the structure of one embodiment of the sliding member (slide switch) of the present invention, showing a cross-sectional view taken along line XX in FIG. 1(a). [Diagram 3] FIG. 3 is a schematic diagram illustrating the structure of one embodiment (multi-stage gear device) of the sliding member of the present invention, in which FIG. 3(a) shows a front view of the multi-stage gear device, and FIG. 3(b) shows a side view (including a partial cross section) of the multi-stage gear device. [Figure 4]FIG. 4 is a schematic diagram of the device used in the friction and wear test (1) (evaluation of lubrication characteristics between metal and resin) carried out in the examples. [Diagram 5] FIG. 5 is a schematic diagram of the device used in the friction and wear test (2) (evaluation of lubrication properties between resins) carried out in the examples. [Figure 6] FIG. 6 shows microscopic photographs (magnification: 200 times) of the grease compositions of Comparative Example 2 and Example 2 ((A): Comparative Example 2, (B): Example 2). [Figure 7] FIG. 7 shows the dynamic friction coefficient versus the amount of fluorine-based surfactant (0% by mass to 3% by mass) in the grease compositions of Comparative Example 2, Example 6, Example 5, Example 2, Example 7, and Comparative Example 6. [Figure 8] FIG. 8 shows the dynamic friction coefficient values ​​as a function of the proportion of the total amount of fluorine-based base oil and fluorine-based thickener (referred to as the "fluorine-based grease content" in the figure) (100% by mass to 70% by mass), when the total mass of the fluorine-based base oil, synthetic hydrocarbon oil, fluorine-based thickener, and lithium soap thickener is taken as 100, for grease compositions with an added amount of 2% by mass of fluorine-based surfactant (○: Comparative Example 9, Examples 1 to 4, Comparative Example 10) and grease compositions with an added amount of 0% by mass of fluorine-based surfactant (■: Comparative Example 7, Comparative Examples 1 to 4). [Figure 9] FIG. 9 shows the static friction coefficient values ​​versus the ratio of the total amount of the fluorine-based base oil and the fluorine-based thickener (referred to as the "fluorine-based grease content" in the figure) (100% by mass to 70% by mass) when the total mass of the fluorine-based base oil, synthetic hydrocarbon oil, fluorine-based thickener, and lithium soap thickener is taken as 100 in the grease compositions of Comparative Example 9, Examples 1 to 4, and Comparative Example 10. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] As mentioned above, in an environment where there is contact with water, such as an underwater environment or an environment where condensation is likely to occur (hereinafter collectively referred to as a water contact environment), there is a problem that the grease is likely to peel off from the applied surface. For example, the slide switch disclosed in Patent Document 1 is provided with a waterproof sheet made of resin to improve waterproofing, considering the possibility of being used in a water contact environment, and as described below, the slide switch turns on and off through this waterproof sheet. At this time, grease is used to improve the lubricity between the waterproof sheet and the slider, and between the slider and other contact surfaces. However, if the grease lacks adhesion, the grease may be removed even during use of the switch (on and off execution), which increases the frictional force between the slider and the waterproof sheet, etc., and may cause wear and damage to the waterproof sheet, etc., which may ultimately lead to a shortened lifespan of the slide switch. In recent years, the load on the waterproof sheet has increased even more due to further miniaturization of the switch components, which increases the occurrence of waterproof sheet breakage, etc., and there is a concern that the lifespan of the switch will be further shortened. Also, depending on the type of slide switch, there are slide switches in which the slider (resin) and other contact surfaces that slide against it, such as the click spring (elastic member), are made of resin, and there are also slide switches in which the click spring is made of metal. It is desirable for the grease used in the latter slide switches to provide good lubrication not only between the waterproof sheet (resin) and slider (resin) but also between the slider (resin) and click spring (metal).

[0009] Conventionally, fluorine-based grease has been used as a grease for resin lubrication of micro slide switches, etc., and in order to improve the adhesion of grease to resin in the above-mentioned water contact environment, a mixture of a fluorine-based lubricant and lithium soap grease, which is a non-fluorine-based lubricant, was adopted. Therefore, efforts have been made to extend the life of slide switches. However, it is difficult to say that the mixture of the above-mentioned fluorine-based lubricant and non-fluorine-based lubricant improves the lubrication between the resin and the metal compared to the case where a fluorine-based lubricant is used alone. Therefore, if such a mixture is used in a switch having a sliding part in which the mating surface against the resin sliding surface (slider) is metal (click spring), there is a concern that the operability (click feeling) of the slide switch will deteriorate. One factor that influences the lubricity is the mutual dispersibility of the mixture. As shown in the results of the Examples described later, when comparing the microscopic observation photographs (FIG. 6) of the grease composition containing a fluorine-based surfactant (Example 2) and the grease composition not containing a fluorine-based surfactant (Comparative Example 2), many aggregates of about 20 to 30 μm were confirmed in the grease composition not containing a surfactant. The presence of such aggregates leads to an increase in the friction coefficient on the sliding surface, and for example, in terms of the lubricity between resin and metal, it is considered that this leads to a deterioration in switch operability. In addition, if sliding is performed under load with these aggregates generated, it is expected that the amount of grease scraped off from the sliding surface will increase, which may cause wear and damage to the waterproof sheet, etc.

[0010] In order to solve these problems, the present inventors have discovered that a grease formulation containing a fluorine-based base oil and a synthetic hydrocarbon oil as base oils, a fluorine-based thickener and a lithium soap thickener or a lithium complex soap thickener as thickeners, an extreme pressure additive, and in particular a fluorine-based surfactant, not only provides the grease with excellent lubricating properties in a water contact environment, but also provides excellent lubricating properties, particularly between resin and metal.

[0011] The grease composition for resin lubrication according to the present invention (hereinafter, simply referred to as "grease composition") is characterized by being a combination of a specific base oil and a specific thickener, which are mixed with a fluorine-based surfactant, as described below. This grease composition can impart excellent lubricating properties to the application site (sliding surface) not only to a resin counter surface, but also to a metal counter surface, in particular. A specific description will be given below.

[0012] [Resin sliding components and resin-metal sliding components] The resin sliding members and resin-metal sliding members to which the grease composition for resin lubrication according to the present invention can be applied are not particularly limited, and examples thereof include slide switches, gear devices, bearings, and the like. The resin sliding member to which the present invention is applied is not particularly limited as long as it is a sliding member having at least a part of a resin sliding surface. The resin-metal sliding member to which the present invention is applied is not particularly limited as long as it is a sliding member having a resin sliding surface and a metal mating surface facing the sliding surface. Therefore, the resin sliding member and the resin-metal sliding member include not only slide switches, gear devices, and bearings as described above, but also various resin sliding members and resin-metal sliding members, and these resin sliding members and resin-metal sliding members are also the subject of the present invention. The resin sliding member of the present invention has a resin sliding surface to which a grease composition for resin lubrication described below is applied (a resin sliding surface at least a portion of which is covered with the grease composition for resin lubrication by being applied or filled and coming into contact with the grease composition). The resin-metal sliding member of the present invention has a resin sliding surface to which a grease composition for resin lubrication described below is applied (a resin sliding surface at least a portion of which is covered with the grease composition for resin lubrication by being applied or filled therein and coming into contact with the resin sliding surface) and a metal mating surface facing the sliding surface. Preferred embodiments of a resin sliding member and a 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.

[0013] [Slide switch] 1 shows a cross section of a slide switch 101 according to a preferred embodiment of the present invention as viewed from the front. A cross section taken along line XX in FIG. 1(a) (a view of the slide switch 101 as viewed from above) is shown in FIG. In the example shown in Figure 1 (and Figure 2), the slide switch 101 includes a housing 102, a cover 103, a first waterproof film 104, a second waterproof film 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 operating portion 113, and a click spring 114.

[0014] 1, the housing 102 and the cover 103 are joined together to form a case. The housing 102 is made of an insulating material, and the cover 103 is made of a metal such as stainless steel. The cover 103 may also be made of an insulating material.

[0015] The first waterproof film 104 and the second waterproof film 105 are provided to enhance the waterproofness of the slide switch 101 as described below, and as shown in FIG. 1, the first waterproof film 104 is attached to the outer surface of the housing 102, and the second waterproof film 205 is attached to the inside of the housing 102.

[0016] Furthermore, first fixed contact 106, second fixed contact 107, and third fixed contact 108 are fixed to housing 102 between first waterproof film 104 and second waterproof film 105. First fixed contact 106, second fixed contact 107, and third fixed contact 108 are separated from each other and electrically insulated by housing 102, and are made of a conductive material. Although not shown, an end of first fixed contact 106, an end of second fixed contact 107, and an end of third fixed contact 108 are exposed at the bottom of housing 102, and are used as connection terminals for connecting to an external circuit.

[0017] The movable contact 109 is made of a conductive material. As shown in Fig. 1, the movable contact 109 is displaceable between a separated position (ON position, Fig. 1(a)) where it is separated from the first fixed contact 106 and the second fixed contact 107, and a contact position (OFF position, Fig. 1(b)) where it is in contact with the first fixed contact 106 and the second fixed contact 107. The movable contact 109 is made of an elastic member configured to take the separated position in an unloaded state (Fig. 1(a)).

[0018] The slider 110 is made of an insulating resin material. As shown in Fig. 1(a), the slider 110 is supported inside the housing 102. The slider 110 is movable in the longitudinal direction of the housing 102 between an OFF position and an ON position (the range indicated by the double arrow in Fig. 1(a) is the movable range of the slider 110). The cover 103 is provided with a slide groove 103a extending in the longitudinal direction of the housing 102, and the slide groove 103a is configured to guide the movement of the slider 110 between the OFF position and the ON position. The slider 110 is also provided with a contact operation unit 113. The contact operation unit 113 is configured to displace the movable contact 109 from the separated position to the contact position via the second waterproof film 105 by moving the slider 110 from the OFF position to the ON position.

[0019] 1(b) shows a state in which the slider 110 has been moved from the state shown in FIG. 1(a) to the ON position along the slide groove 103a. As the slider 110 moves, a contact operation unit 113 provided on the slider 110 displaces the movable contact 109 via the second waterproof film 105. When the movable contact 109 comes into contact with 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. To release the conductive state between first fixed contact 106 and second fixed contact 107, the above operation is carried out in reverse. That is, slider 110 is moved toward the OFF position along slide groove 103a, and the pressing of movable contact 109 by contact operation unit 113 is released. Movable contact 109 returns to the separated position by its own elastic restoring force. That is, the contact state between movable contact 109 and first fixed contact 106 and second fixed contact 107 is released.

[0020] According to the above-mentioned configuration, the first fixed contact 106, the second fixed contact 107, and the movable contact 109 are disposed between the first waterproof film 104 and the second waterproof film 105, and the first and second waterproof films 104 and 105 are connected and disconnected via the second waterproof film 105 by the contact operation unit 113 provided on the slider 110. Moisture may enter the housing 102 from the outside through the opening of the slide groove 103a.

[0021] The slide switch 101 also includes a pair of click springs (elastic members) 114. Each click spring 114 includes a protrusion 114a. On the other hand, the slider 110 includes a pair of protrusions 110a. As shown in FIG. 1 (and FIG. 2), when the slider 110 moves between the OFF position (FIGS. 1(a) and 2) and the ON position (FIG. 1(b)), each convex portion 110a of the slider 110 elastically deforms the opposing click spring 114, displacing the convex portion 114a of the click spring 114 in the short direction of the housing 102 (the direction perpendicular to the paper surface of FIG. 1, and the up-down direction of the paper surface of FIG. 2). When each convex portion 110a of the slider 110 passes over the convex portion 114a of the opposing click spring 114, the elastic restoring force of the click spring 114 assists the movement of the slider 110 to the ON position or the OFF position, and also gives a clicking sensation of the switch.

[0022] In the slide switch 101, the second waterproof film 105 is formed of, for example, a polyamide resin such as nylon or a polyphthalamide (PPA) resin material. The slider 110 may be formed of, for example, an insulating resin material such as polyamide (PA), polyphenylene sulfide (PPS), polyphthalamide (PPA), etc. The click spring 114 is formed of the above insulating materials, polycarbonate (PC), polyacetal (POM), polyether ether ketone (PEEK), reinforced plastic, or other resin material having spring properties, or a metal material having spring properties such as stainless steel, carbon steel, carbon tool steel, or other special steel (cold-rolled steel for springs). In the slide switch 101 of this embodiment, the grease composition G for resin lubrication according to the present invention is applied to the contact points of the contact operation part 113 of the slider 110 with the second waterproof film 105 (the lower part of the slider 110 is the resin sliding surface), and the contact points of each convex part 110a of the slider 110 with each convex part 114a of the click spring 114 (each convex part 110a of the slider 110 is the 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, even in an environment where water has infiltrated into the housing 102 from the slide groove 103a, the grease composition G is used, which has excellent adhesion to the resin sliding surface described below and excellent lubricity of the grease itself. Therefore, friction and wear are suppressed in the slide switch 101, and a long life is achieved.

[0023] [Gear system] As an example of a gear device according to a preferred embodiment of the present invention, a multi-stage gear device provided in an actuator will be described. The "multi-stage gear device" to which the grease composition for resin lubrication according to the present invention is applied refers to a multi-stage gear device having gears in which at least one gear is made of resin, and in the multi-stage gear device, resin gears and gears made of materials other than resin, such as metal gears, may be mixed, or the multi-stage gear device may be composed only of resin gears. The present invention includes an embodiment of a gear device in which a resin gear and a gear meshing with the resin gear are metal gears. A grease composition for resin lubrication, which will be described later, is applied to the bearing portions of the resin gears, and to the meshing portions between the resin gears and gears made of resin or materials other than resin, particularly to the meshing portions between the resin gears and metal gears.

[0024] Fig. 3 is a schematic diagram of a multi-stage gear device 201 provided in an actuator, with Fig. 3(a) being a front view of the multi-stage gear device 201 and Fig. 3(b) being a side view (including a partial cross section) of the multi-stage gear device 201. Note that Fig. 3(b) also illustrates, in addition to the multi-stage gear device 201, a motor 211 and its output shaft 211a, and an actuator output shaft 212. The multi-stage gear device 201 shown in Fig. 3 includes a first stage gear 202 attached to an output shaft 211a of a motor 211 so as to be rotatable together with the motor, a second stage gear 203 meshed with the first stage gear 202, and a third stage gear 205 meshed with the second stage gear 203. Fig. 3 also illustrates a shaft 204 of the second stage gear 203 and a shaft 206 of the third stage gear 205, as well as the output shaft 212 of the actuator described above. In this embodiment, a grease composition for resin lubrication, which will be described later, is applied to the meshing portion X between the first stage gear 202 and the second stage gear 203, the meshing portion Y between 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 in Figure 3. In one embodiment, the first stage gear 202 and the third stage gear 205 in FIG. 3 may be metal gears, and the second stage gear 205 may be a plastic gear.

[0025] In the above-mentioned multi-stage gear device 201, the shafts constituting the device, i.e., each shaft (204, 206) of the multi-stage gear device, as well as the output shaft 202a of the motor and the output shaft 212 of the actuator, may be made of either metal or resin, and may be configured, for example, as follows. 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, so there is no bearing between the first stage gear 202 and the output shaft 211a that rotates relatively. 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 made of resin and are fixed shafts. The second stage gear 203 and the third stage gear 205 rotate while sliding on their respective fixed shafts. For this reason, a grease composition for resin lubrication, which will be described later, is applied to the bearing portion 204a between the second stage gear 203 and the shaft 204 (fixed shaft) of the second stage gear, and to the bearing portion 206a between the third stage gear 205 and the shaft 206 (fixed shaft) of the third stage gear, in addition to the meshing portions X and Y between the gears.

[0026] Resins that can be used as resin components constituting these gear devices (gears, gear shafts) and actuators equipped with these gear devices (motor output shaft, base member, exterior member (case), actuator output shaft, etc.) include polyethylene (PE), polypropylene (PP), ABS resin (ABS), polyacetal (POM), polyamide (PA), polycarbonate (PC), phenolic resin (PF), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), polyethersulfone (PES), polyimide (PI), polyetheretherketone (PEEK), etc. Metallic materials such as carbon steel, chromium steel, chromium-molybdenum alloy steel, and stainless steel may be used for the metallic members that make up these gear devices.

[0027] The gear device of this embodiment is suitable for use in an actuator used in an on-vehicle air conditioning system, etc. On-vehicle air conditioning systems are used at a wide range of temperatures from -40°C to 100°C, and if they are used in such a temperature cycle, condensation may form inside the actuator, causing water droplets to adhere to the tooth surface and grease. The gear device of this embodiment can also be suitably used in actuators used in automatic opening and closing devices for toilet seats and toilet lids, etc. In automatic opening and closing devices for toilet seats and the like, water may splash on the actuator during flushing, etc. Even in gear devices used in environments where they are likely to come into contact with water, application of the grease composition for resin lubrication of the present invention reduces friction and wear, thereby achieving a longer product life.

[0028] [Grease composition for resin lubrication] The grease composition for resin lubrication of the present invention will be described below.

[0029] <Base oil> In the grease composition for resin lubrication according to this embodiment, a fluorine-based base oil and a synthetic hydrocarbon oil are used as the base oil.

[0030] An example of a fluorine-based base oil is one whose main component is perfluoropolyether (PFPE). PFPE has the general formula: RfO(CF 2 O) p (C 2 F 4 O) q (C 3 F 6 O) r It is a compound represented by Rf (Rf: perfluoro lower alkyl group, p, q, r: integers). Perfluoropolyethers are broadly classified into straight-chain and side-chain types, and the temperature dependency of the kinetic viscosity of the straight-chain type is smaller than that of the side-chain type. This means that the straight-chain type has a lower viscosity than the side-chain type in a low-temperature environment, and a higher viscosity than the side-chain type in a high-temperature environment. For example, when assuming use in a high-temperature environment, it is desirable for the viscosity to be high in a high-temperature environment in order to prevent the grease from leaking out from the application area and the associated depletion, that is, the use of straight-chain perfluoropolyether is preferable.

[0031] Furthermore, the inventors have investigated the composition for achieving an optimum friction coefficient value, which is an index of lubrication properties, and have found that in addition to the composition of the grease composition, the kinetic viscosity value of the fluorine-based base oil is also an important factor. As shown in the results of the Examples described later, in a grease composition containing a specific base oil, a thickener, an extreme pressure additive, and a fluorine-based surfactant, when the kinematic viscosity value of the fluorine-based base oil at 40°C was changed in various ways (392 mm 2 / s (Example 5), 300 mm 2 / s (Example 8), 200 mm 2 / s (Comparative Example 5)), the value of the dynamic friction coefficient gradually increased as the value of the dynamic viscosity decreased. 2 It was confirmed that when the friction coefficient falls below 0.055 / s, the value of the kinetic friction coefficient exceeds 0.060. As shown by the above results, in the grease composition for resin lubrication of the present invention, the fluorine-based base oil has a kinematic viscosity of 300 mm at 40° C. 2 / s or more, especially the kinematic viscosity is 390mm 2 It is preferable that the ratio is 1 / s or more.

[0032] As the synthetic hydrocarbon oil, for example, normal paraffin, isoparaffin, polybutene, polyisobutylene, 1-decene oligomer, 1-decene and ethylene co-oligomer and other polyalphaolefins (PAO) are preferable.

[0033] The blending ratio of the fluorine-based base oil and the synthetic hydrocarbon oil is not particularly limited, but for example, relative to 100% by mass of the total amount of the base oils, the fluorine-based base oil:synthetic hydrocarbon oil may be 99-5% by mass:1-95% by mass, for example, 99-10% by mass:1-90% by mass, 98-20% by mass:2-80% by mass, 98-30% by mass:2-70% by mass, 98-50% by mass:2-50% by mass, preferably 98-65% by mass:2-35% by mass, and particularly preferably 98-70% by mass:2-30% by mass. The ratio of the total base oil, which is the sum of the fluorine-based base oil and the synthetic hydrocarbon oil, to the total mass of the grease composition of the present invention is 60 to 90 mass%, for example, 65 to 80 mass%, or 65 to 75 mass%. It is possible.

[0034] <Thickener> In the grease composition of the present invention, a fluorine-based thickener and a lithium soap thickener or a lithium complex soap thickener are added as thickeners.

[0035] <Fluorine-based thickener> As the fluorine-based thickener, fluororesin particles are preferred, and for example, particles of polytetrafluoroethylene (PTFE) are preferably used. PTFE is a polymer of tetrafluoroethylene and has the general formula: [C 2 F 4 ] n (n: degree of polymerization). Other usable fluorine-based thickeners include, for example, perfluoroethylene propylene copolymer (FEP), ethylene tetrafluoroethylene copolymer (ETFE), and tetrafluoroethylene perfluoroalkyl vinyl ether copolymer (PFA). The size of the PTFE particles is not particularly limited, but for example, polytetrafluoroethylene with an average particle size of 0.1 μm to 100 μm can be used. The shape of the PTFE particles is not particularly limited, and they may be spherical, polyhedral, acicular, etc.

[0036] The fluorine-based thickener is used in an amount of 1 to 40 mass %, for example 10 to 30 mass %, or 20 to 30 mass %, based on the total mass of the grease composition.

[0037] <Lithium soap thickener / Lithium complex soap thickener> In the present invention, a lithium soap thickener is used in addition to the above-mentioned fluorine-based thickener. As the lithium soap thickener, a lithium salt of an aliphatic monocarboxylic acid can be used. The aliphatic carboxylic acid may be linear, branched, saturated or unsaturated, and generally, a fatty acid having about 2 to 30 carbon atoms, for example, 12 to 24 carbon atoms, can be used. Specific examples include 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, ricilenic acid, and ricinoleic acid (ricinoleic acid). Among them, representative examples of the lithium soap thickener include lithium salts of stearic acid, lauric acid, and ricinoleic acid, and lithium salts of compounds in which the above acids are substituted with a hydroxy group.

[0038] In the present invention, a lithium complex soap thickener may be used in place of the lithium soap thickener. Lithium complex soap thickeners have improved heat resistance compared to lithium soap thickeners by combining higher fatty acids with dibasic acids or inorganic acids (such as boric acid). The lithium complex soap thickener can be obtained, for example, by reacting lithium hydroxide with an aliphatic monocarboxylic acid having about 12 to 24 carbon atoms and containing at least one hydroxyl group, and an aliphatic dicarboxylic acid having about 2 to 12 carbon atoms. Examples of the aliphatic monocarboxylic acid having 12 to 24 carbon atoms and containing at least one hydroxy group include hydroxylauric acid, hydroxypalmitic acid, hydroxystearic acid, hydroxyoleic acid, hydroxyarachidic acid, hydroxybehenic acid, and hydroxylignoceric acid. Examples of the aliphatic dicarboxylic acids having 2 to 12 carbon atoms include oxalic acid, malonic acid, succinic acid, methylsuccinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, and azelate. Examples of the acid include rhenic acid, sebacic acid, nonamethylene dicarboxylic acid, and decamethylene dicarboxylic acid. These monocarboxylic acids and dicarboxylic acids may be used alone or in combination of two or more. For example, a representative example of the lithium complex soap thickener is one obtained by reacting lithium hydroxide with a combination of hydroxystearic acid and azelaic acid.

[0039] The lithium soap thickener or lithium complex soap thickener is used in an amount of 0.1 to 15 mass %, for example 0.2 to 5 mass %, based on the total mass of the grease composition. Used in.

[0040] The total amount of the fluorine-based thickener and the lithium soap thickener or the lithium complex soap thickener (total amount of thickeners) can be blended in an amount of 5 to 40 mass%, for example 10 to 30 mass%, preferably 15 to 30 mass%, and particularly 20 to 30 mass%, relative to the total mass of the grease composition for resin lubrication.

[0041] In the present invention, when the total mass of the fluorine-based base oil, synthetic hydrocarbon oil, fluorine-based thickener, and lithium soap thickener or 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 lithium complex soap thickener can be, for example, [A]:[B]=99 to 60:1 to 40, for example, 98-70:2 to 30, 98-75:2 to 25, 98-80:2 to 20, 98-85:2 to 15, or 98-90:2 to 10.

[0042] <Fluorosurfactant> The grease for resin lubrication of the present invention contains a fluorine-based surfactant. Examples of the fluorine-containing surfactant include fluorine-containing sulfonate esters, fluorine-containing sulfate esters, fluorine-containing phosphate esters, fluorine-containing alkylsulfonic acids, and fluorine-containing alkylcarboxylic acids. For example, fluorine-containing phosphate esters can be used.

[0043] The present inventors have investigated compositions for achieving an optimal coefficient of friction, which is an index of lubrication characteristics, in particular the optimal coefficient of friction between resin and metal, and have found that in addition to the composition of the grease composition, the incorporation of a fluorine-based surfactant is essential, and that the amount of the surfactant incorporated is also an important factor. As an example, FIG. 7 shows the results of a friction and wear test (between metal and resin) of a grease composition containing a specific base oil, a thickener, and an extreme pressure additive, in which the amount of fluorosurfactant blended was varied (0 to 3 mass%). As shown in Figure 7, when no fluorosurfactant was added, the dynamic friction coefficient between metal and resin was slightly above 0.060 (0.061), but it was confirmed that the dynamic friction coefficient value decreased by adding a fluorosurfactant. However, when the amount added reached 3 mass%, it was confirmed that the dynamic friction coefficient value rose sharply, reaching a value (0.071) higher than when no surfactant was added. In this way, the fluorine-based surfactant is used in an amount of 0.1 to 100% by weight based on the total weight of the grease composition. 2.5 mass%, preferably 0.5 to 2.5 It can be used in an amount of % by weight, for example 1 to 2% by weight.

[0044] <Extreme pressure additives> The resin lubricating grease of the present invention contains an extreme pressure additive (extreme pressure agent). Extreme pressure additives are known to have functions such as reducing friction and wear on metal surfaces and preventing seizure by reacting with metal surfaces to form a lubricating film. It may be thought that resin lubricating grease containing additives has no effect on resin sliding surfaces, but the present inventors have discovered that even when an extreme pressure additive is added, the coefficient of friction decreases when the grease is applied to a resin sliding surface.

[0045] Examples of the extreme pressure additive include phosphorus-based compounds, sulfur-based compounds, chlorine-based compounds, metal salts of sulfur-based compounds, and polymer esters. In particular, in the present invention, it is preferable to use at least one of phosphorus-based compounds (phosphorus-based additives) and polymer esters (polymer ester-based additives) as the extreme pressure additive, and these may be used in various combinations.

[0046] Examples of the phosphorus-based additives include phosphates, phosphites, phosphate amine salts, and thiophosphates. Suitable phosphorus-based additives include, for example, phosphoric acid triesters such as tricresyl phosphate (TCP), triphenyl phosphate, tributyl phosphate, trioctyl phosphate, and trioleyl phosphate, and thiophosphoric acid triesters such as triphenoxyphosphine sulfide (TPPS), which are also commercially available.

[0047] Examples of the polymer ester include esters of aliphatic monovalent carboxylic acids and divalent carboxylic acids with polyhydric alcohols. Specific examples of the polymer ester include, but are not limited to, the PERFAD (registered trademark) series and the PRIOLUBE (registered trademark) series manufactured by Croda Japan.

[0048] The extreme pressure additive can be used in an amount of 0.005 to 10 mass %, preferably 0.01 to 5 mass %, for example 0.01 to 1 mass %, based on the total mass of the grease composition.

[0049] <Other additives> In addition to the above essential components, the grease composition for resin lubrication may contain additives that are usually used in grease compositions, as necessary, within the range that does not impair the effects of the present invention. Examples of such additives include antioxidants, metal deactivators, rust inhibitors, oiliness improvers, viscosity index improvers, and thickeners. When these other additives are contained, the amount (total amount) of them added is usually 0.1 to 10 mass % based on the total mass of the grease composition.

[0050] Examples of the antioxidant include octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 2,4-bis-(n-octylthio)-6-(4-hydroxy-3,5-di-t-butylanilino)-1,3,5-triazine, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol-bis[3-(3,5 hindered phenol-based antioxidants such as 2,2-thio-diethylenebis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 2,2-thio-diethylenebis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], and N,N'-hexamethylenebis(3,5-di-t-butyl-4-hydroxy-hydrocinnamide); phenol-based antioxidants such as 2,6-di-t-butyl-4-methylphenol and 4,4-methylenebis(2,6-di-t-butylphenol); and amine-based antioxidants such as triphenylamine, phenyl-α-naphthylamine, alkylated phenyl-α-naphthylamine, phenothiazine, and alkylated phenothiazine.

[0051] Examples of the metal deactivator include benzotriazole and sodium nitrite.

[0052] The grease composition for resin lubrication of the present invention can be obtained by mixing the above-mentioned various base oils with various thickeners, fluorine-based surfactants and extreme pressure additives in prescribed ratios, and by blending other additives as desired. Also, a grease composition for resin lubrication can be obtained by blending two types of base greases, namely, a fluorine-based grease consisting of a fluorine-based base oil and a fluorine-based thickener, and a lithium soap grease (or a lithium complex soap grease) consisting of a synthetic hydrocarbon oil and a lithium soap thickener (or a lithium complex soap thickener), a fluorine-based surfactant, an extreme pressure additive, and other additives as desired. Alternatively, a grease composition for resin lubrication can be produced by blending one of the base greases with the remaining base oil, the thickener, the fluorine-based surfactant, the extreme pressure additive, and other additives as desired. Typically, the content of thickener in the base grease is about 10 to 30 mass%. For example, in the above two types of base grease, the content of each thickener in each base grease can be, respectively, fluorine-based thickener: 15 to 30 mass%, and lithium soap or lithium complex soap-based thickener: 10 to 20 mass%,. The blending ratio of the above two types of base greases (mass ratio, total 100) can be, for example, fluorine-based grease:lithium soap grease or lithium complex soap grease=99-60:1-40, for example, 98-70:2-30, 98-75:2-25, 98-80:2-20, 98-85:2-15, or 98-90:2-10.

[0053] The grease composition for resin lubrication of the present invention is a relatively soft grease since it is applied to a resin sliding surface.

[0054] The present invention is not limited to the embodiments and specific examples described in this specification, and various changes and modifications are possible within the scope of the technical ideas described in the claims. EXAMPLES

[0055] The present invention will be described in more detail below with reference to examples, although the present invention is not limited thereto.

[0056] [Evaluation of grease compositions for resin lubrication] The grease compositions used in Examples 1 to 12 and Comparative Examples 1 to 10 were prepared in the amounts shown in the following tables.

[0057] The details and abbreviations of the components used in preparing the grease are as follows: (a) Base oil (a1) Fluorine-based base oil: Linear perfluoropolyether (PFPE) oil (a1-1) Linear PFPE oil 1 (Kinematic viscosity at 40 ° C: 392 mm 2 / s) (a1-2) Linear PFPE oil 2 (Kinematic viscosity at 40 ° C: 300 mm 2 / s) (a1-3) Linear PFPE oil 3 (Kinematic viscosity at 40 ° C: 200 mm 2 / s) (a2) Synthetic hydrocarbon oil: polyalphaolefin (PAO) (a2-1) PAO1 (Kinematic viscosity at 40°C: 30mm 2 / s) (a2-2) PAO2 (Kinematic viscosity at 40°C: 100mm 2 / s) (a2-3) PAO3 (Kinematic viscosity at 40°C: 200mm 2 / s) (a2-4) PAO4 (Kinematic viscosity at 40°C: 18mm 2 / s) (a2-5) PAO5 (Kinematic viscosity at 40°C: 300mm 2 / s) (b) Thickener (b1) Fluorine-based thickener: PTFE (polytetrafluoroethylene) resin (particle size 10 00nm) (b2) Li soap thickener: 12OHLi soap (lithium 12-hydroxystearate) (c) Additives (c1) Fluorine-based surfactant: fluorine-containing phosphate ester, product name "Megafaq F-510" (c2) Extreme pressure additive: Tricresyl phosphate (TCP), product name "Tritolyl phosphate", manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. (c3) Antioxidant: diarylamine-based antioxidant, product name "IRGANOX L57", BASF Japan Ltd.

[0058] The properties of the obtained grease composition were evaluated by the following procedures: metal-resin lubrication properties (friction and wear properties (1)) and resin-resin (resin pin-resin film) lubrication properties (friction and wear test (2)).

[0059] <Test Method> 1. Evaluation of lubrication characteristics between metal and resin: Friction and wear test (1) Dynamic friction coefficient As shown in the conceptual diagram of the friction and wear test in Figure 4, each grease composition was applied to a flat plate (cold-rolled steel plate) to prepare a laminated sample. A probe (resin pin) was slid on the surface of the flat plate (cold-rolled steel plate) of this laminated sample under a specified load, and the friction coefficient was measured when the probe was moving at a constant speed. Measurements were performed during a sliding cycle of five strokes, and the average value of the obtained values ​​was taken as the kinetic friction coefficient for each measurement. The test was carried out three times for each of the grease compositions of the Examples and Comparative Examples, and the average value of the three tests was regarded as the dynamic friction coefficient of each grease composition. The lubricating properties were evaluated according to the evaluation criteria shown below. <Test conditions> Measurement equipment: Shinto Scientific Co., Ltd., variable load friction and wear test system HHS2000 Measurement conditions: Test in air Probe: Resin pin (Pin diameter: 2.5mm, Pin type: PPA resin) Feed scale: 10mm Load capacity: 50g -Sliding speed: 0.5mm / sec Sliding cycle: 5 strokes <Evaluation criteria> Under the test conditions in this example, a lower dynamic friction coefficient indicates better lubrication properties. It has been confirmed that when the dynamic friction coefficient value exceeds 0.060, the clicking operation deteriorates in the actual switch, so a value of 0.060 or less is preferable. A (Good): Dynamic friction coefficient is 0.060 or less N (unsuitable): Dynamic friction coefficient exceeds 0.060

[0060] 2. Evaluation of lubrication characteristics between resins: Friction and wear test (2) Static friction coefficient As shown in the conceptual diagram of the friction and wear test in Figure 5, a nylon sheet was placed on a flat plate, and each grease composition was applied thereon to prepare a laminated sample, which was then immersed in water. In the immersed state, a probe (resin pin) was slid on the surface of the nylon sheet of the laminated sample at a specified load, and the friction coefficient at that time was measured. Measurements were performed during a sliding cycle of 200 strokes, and the maximum value obtained was taken as the static friction coefficient in each measurement (the highest friction coefficient value corresponds to the static friction coefficient at the moment the probe starts moving or stops). The test was carried out three times for each of the grease compositions of the Examples and Comparative Examples, and the average value of the three tests was regarded as the static friction coefficient of each grease composition. The lubrication properties were evaluated. <Test conditions> Measurement equipment: Shinto Scientific Co., Ltd., variable load friction and wear test system HHS2000 Measurement conditions: Underwater test Probe: Resin pin (Pin diameter: 2.5mm, Pin type: PPA resin) Feed scale: 3mm Load capacity: 1000g -Sliding speed: 1.0mm / sec Sliding cycle: 200 strokes <Evaluation criteria> Under the test conditions of this example, a lower static friction coefficient indicates better lubrication properties. It has been confirmed that when the static friction coefficient value exceeds 0.120, tears occur in the waterproof film in the actual switch, so a static friction coefficient of 0.120 or less is preferable. A (Good): Static friction coefficient is 0.120 or less N (unsuitable): Static friction coefficient exceeds 0.120

[0061] The results are shown in Tables 1 and 2. The blend amounts (mass %) in the tables are values ​​relative to the total mass of the composition (however, due to rounding to two decimal places, the total may not amount to 100 mass %). In the tables, the fluorine-based base oil and fluorine-based thickener are collectively referred to as "fluorine-based grease," and the synthetic hydrocarbon oil and lithium soap thickener are collectively referred to as "Li soap grease." FIG. 6 shows micrographs of the grease compositions of Comparative Example 2 (FIG. 6(A)) and Example 2 (FIG. 6(B)), and FIG. 7 shows the dynamic friction coefficient values ​​versus the amount of fluorine-based surfactant (0% by mass to 3% by mass) in the grease compositions of Comparative Example 2, Example 6, Example 5, Example 2, Example 7, and Comparative Example 6. FIG. 8 shows the dynamic friction coefficient values ​​as a function of the ratio of the total amount of fluorine-based base oil and fluorine-based thickener (referred to as the "fluorine-based grease content" in the figure) (100% by mass to 70% by mass), when the total mass of the fluorine-based base oil, synthetic hydrocarbon oil, fluorine-based thickener, and lithium soap thickener is taken as 100, for grease compositions with an added amount of 2% by mass (○: Comparative Example 9, Examples 1 to 4, Comparative Example 10) and grease compositions with an added amount of 0% by mass of fluorine-based surfactant (■: Comparative Example 7, Comparative Examples 1 to 4). FIG. 9 shows the static friction coefficient values ​​versus the ratio of the total amount of fluorine-based base oil and fluorine-based thickener (referred to as "fluorine-based grease content" in the figure) (100% by mass to 70% by mass), when the total mass of the fluorine-based base oil, synthetic hydrocarbon oil, fluorine-based thickener, and lithium soap thickener is taken as 100, for the grease compositions of Comparative Example 9, Examples 1 to 4, and Comparative Example 10.

[0062] [Table 1]

[0063] [Table 2]

[0064] FIG. 6 shows microscopic photographs of the grease compositions of Comparative Example 2 (FIG. 6(A)) and Example 2 (FIG. 6(B)). As shown in FIG. 6, a large number of aggregates of about 20 to 30 μm were confirmed in the grease composition without surfactant (FIG. 6(A)) compared to the grease composition with surfactant (FIG. 6(B)). The presence of the aggregates increases the coefficient of friction (dynamic friction coefficient) on the sliding surface. This is thought to have led to an increase in the number of contacts and the static friction coefficient.

[0065] FIG. 7 shows the results of friction and wear tests (dynamic friction coefficient values) for grease compositions in which the amount of fluorosurfactant mixed was changed from 0 mass% to 3 mass% (Comparative Example 2, Example 6, Example 5, Example 2, Example 7, Comparative Example 6). The horizontal axis of the graph shown in Fig. 7 is the amount (mass%) of the fluorosurfactant in the grease composition, and the vertical axis is the measured value of the dynamic friction coefficient. In Fig. 7, the dashed line parallel to the horizontal axis indicates the dynamic friction coefficient value: 0.060. As shown in Figure 7, when no fluorosurfactant was added, the kinetic friction coefficient between metal and resin was slightly above 0.060 (0.061), but it was confirmed that by adding a fluorosurfactant, the kinetic friction coefficient value decreased to below 0.060. However, when the amount added was 3 mass%, it was confirmed that the kinetic friction coefficient value rose sharply, reaching a value (0.071) higher than when no surfactant was added.

[0066] FIG. 8 shows the results (dynamic friction coefficient values) of friction and wear tests for grease compositions with 2 mass% fluorosurfactant added (○: Comparative Example 9, Examples 1 to 4, Comparative Example 10) and 0 mass% fluorosurfactant added (■: Comparative Example 7, Comparative Examples 1 to 4) when the total mass of the fluorous base oil, synthetic hydrocarbon oil, fluorous thickener, and lithium soap thickener is taken as 100 and the ratio of the total amount of the fluorous base oil and fluorous thickener (referred to as the "fluorous grease content" in the figure) is changed from 100 mass% to 70 mass%. The horizontal axis of the graph shown in Fig. 8 is the ratio (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, synthetic hydrocarbon oil, fluorine-based thickener, and lithium soap thickener is taken as 100, and the vertical axis is the measured value of the dynamic friction coefficient. In Fig. 8, the dashed line parallel to the horizontal axis indicates the dynamic friction coefficient value: 0.060. As shown in Figure 8, when the amount of fluorosurfactant added was either 2 mass% (indicated by ○ in the figure) or 0% (indicated by ■ in the figure), there was a tendency for the dynamic friction coefficient value to increase as the ratio of the total amount of fluorobase oil and fluorothickener decreased. When the amount of fluorosurfactant added was 2% by mass (○), the coefficient of dynamic friction between resin and metal was below 0.060 when the ratio of the total amount of fluorobase oil and fluorothickener was in the range of 100% by mass (i.e., when synthetic hydrocarbon oil and lithium soap thickener were not blended) to 75% by mass. On the other hand, when the amount of fluorosurfactant added was 0% by mass (■), the coefficient of dynamic friction was below 0.060 when the ratio of the total amount of fluorobase oil and fluorothickener was 100% by mass, but by blending synthetic hydrocarbon oil and lithium soap thickener, the coefficient of dynamic friction exceeded 0.060.

[0067] FIG. 9 shows the results of friction and wear tests (static friction coefficient values) of grease compositions (Comparative Example 9, Examples 1 to 4, Comparative Example 10) in which the ratio of the total amount of the fluorine-based base oil and the fluorine-based thickener (referred to as the "fluorine-based grease content" in the figure) was changed from 100 mass% to 70 mass%, assuming that the total mass of the fluorine-based base oil, synthetic hydrocarbon oil, fluorine-based thickener, and lithium soap thickener is 100. The horizontal axis of the graph shown in Fig. 9 is the ratio (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, synthetic hydrocarbon oil, fluorine-based thickener, and lithium soap thickener is taken as 100, and the vertical axis is the measured static friction coefficient value. In Fig. 9, the dashed line parallel to the horizontal axis indicates the static friction coefficient value: 0.120. As shown in Figure 9, when the total ratio of the fluorine-based base oil and fluorine-based thickener is 100 mass% (i.e., when synthetic hydrocarbon oil and lithium soap thickener are not blended), the static friction coefficient between resins exceeds 0.120. By blending synthetic hydrocarbon oil and lithium soap thickener, the static friction coefficient value decreases sharply, A tendency for the static friction coefficient to fall below 0.120 was confirmed. However, when the amount of synthetic hydrocarbon oil and lithium soap thickener was increased and the total ratio of the fluorine-based base oil and fluorine-based thickener reached 70 mass%, the static friction coefficient again exceeded 0.120.

[0068] As shown in Table 1, the grease compositions of Examples 1 to 12 all had a dynamic friction coefficient of 0.060 or less and a static friction coefficient of 0.120 or less, and were confirmed to have excellent lubrication properties between metal and resin and between resin and resin. As shown in Examples 5 and 8, the kinetic viscosity at 40° C. is 300 mm 2 By using a fluorine-based base oil with a kinematic viscosity in the range of 390 mm / s or more, excellent lubrication properties can be obtained. 2 By using a fluorine-based base oil having a viscosity of 100 / s or more (Example 5), results showing even more excellent lubricating properties were obtained. Furthermore, as shown in Examples 2 and 5 to 7, when the blending ratio of the fluorine-based surfactant was changed from 0.5% by mass to 2.5% by mass, excellent results in lubrication properties were obtained. As shown in Examples 1 to 4, excellent lubricating properties were obtained even when the mass ratio of the total amount [A] of the fluorine-based base oil (a1) and the fluorine-based thickener (b1) to the total amount [B] of the synthetic hydrocarbon oil (a2) + lithium soap thickener (b2) was changed from [A]:[B] = 98:2 to 75:25. As shown in Examples 5 and 8 to 12, the synthetic hydrocarbon oil has a kinematic viscosity at 40° C. of 18 to 200 mm 2 Even when the lubricating oil ratio was changed within the range of / s, excellent lubricating properties were obtained.

[0069] On the other hand, as shown in Table 2, the grease compositions of Comparative Examples 1 to 4, which did not contain a fluorosurfactant, had low static friction coefficients (0.109 or less), but poor dynamic friction coefficients (0.061 to 0.105), resulting in inferior metal-resin lubrication properties compared to the grease compositions of the Examples. The grease compositions of Examples 1 to 4 had dynamic friction coefficients of 0.060 or less (0.031 to 0.056), and this result shows that by blending a fluorosurfactant, the dynamic friction coefficient can be reduced by approximately 30% to 50%.

[0070] In addition, the kinetic viscosity at 40°C is 300mm 2 Fluorine-based base oil (kinetic viscosity: 200 mm / s or less) 2 The grease composition of Comparative Example 5 using a grease having a viscosity of 1000 MPa (0.015 / s) also had a poor dynamic friction coefficient (0.067), resulting in inferior lubrication properties between metal and resin compared to the grease compositions of the Examples.

[0071] On the other hand, the grease compositions of Comparative Examples 7 to 9, which used only a fluorine-based base oil and a fluorine-based thickener, and did not use a synthetic hydrocarbon oil, a lithium soap thickener or a lithium complex soap thickener, or an extreme pressure additive, had poor static friction coefficients (0.124 or more).

[0072] Furthermore, the grease composition of Comparative Example 6, in which the blending amount of fluorosurfactant was 3.0 mass%, showed a significantly worse dynamic friction coefficient (Example 2: 0.042, Comparative Example 6: 0.071) than the grease composition of Example 2, in which the blending amount of fluorosurfactant was 2.0 mass%, resulting in worsening of the lubrication properties between metal and resin. Furthermore, the grease composition of Comparative Example 10, in which the mass ratio of the total amount [A] of the fluorine-based base oil (a1) and the fluorine-based thickener (b1) to the total amount [B] of the synthetic hydrocarbon oil (a2) + lithium soap thickener (b2) was [A]:[B] = 70:30, showed increased dynamic friction coefficient (Example 4: 0.056, Comparative Example 10: 0.067) and static friction coefficient (Example 4: 0.117, Comparative Example 10: 0.122) compared to the grease composition of Example 4, in which the mass ratio was 75:25, and it was confirmed that the lubrication properties were decreased both between metal and resin and between resin and resin. From the results of the above comparative examples, in order to satisfy the lubrication characteristics between metal and resin and between resin and resin, the blending amount of the fluorosurfactant should be 3.0 mass % or less. It was also confirmed that it is more preferable to set the mass ratio of the total amount [A] of the fluorine-based base oil (a1) and the fluorine-based thickener (b1) to the total amount [B] of the synthetic hydrocarbon oil (a2) + the lithium soap thickener (b2) to be [A]:[B] = 98:2 to 75:25.

[0073] As described above, it has been confirmed that the grease composition for resin lubrication of the present invention, which contains a fluorine-based base oil and a synthetic hydrocarbon oil, a fluorine-based thickener and a lithium soap thickener, and an extreme pressure additive, has excellent lubricating properties for resin sliding surfaces, particularly when the mating surface of the sliding surface is made of not only resin but also metal, and it has been found that the application of this grease composition makes it possible to provide resin sliding members and resin-metal sliding members that are capable of suppressing friction and wear and achieving a longer life.

[0074] Although the best embodiment has been described in detail above, the present invention is not limited to the above embodiment, and modifications and improvements within the scope of the present invention that can achieve the object of the present invention are included in the present invention. [Explanation of symbols]

[0075] 101...slide 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...projection, 113...contact operation portion, 114...click spring, 114a...projection 201...Multi-stage plastic gear device, 202...First stage gear, 203...Second stage gear, 204...Shaft of second stage gear, 204a...Bearing portion (grease applied portion), 205...Third stage gear, 206...Shaft of third stage gear, 206a...Bearing portion (grease applied portion), X...Meshing portion between first stage gear and second stage gear, Y...Meshing portion between second stage gear and third stage gear, 211...Motor, 211a...Motor output shaft, 212...Actuator output shaft

Claims

1. A grease composition for resin lubrication to be applied to a resin sliding surface, comprising: Fluorine-based base oil and synthetic hydrocarbon oil, A fluorine-based thickener, a lithium soap thickener or a lithium complex soap thickener, A fluorosurfactant, and an extreme pressure additive, The fluorine-based base oil has a kinetic viscosity of 300 mm at 40° C. ２ / s or more, The fluorosurfactant is a fluorine-containing phosphate ester, 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; Grease composition for resin lubrication.

2. The fluorine-based surfactant is blended in an amount of 0.5 to 2.5 mass% based on the total mass of the grease composition for resin lubrication. The grease composition for resin lubrication according to claim 1.

3. At least a part of the mating surface facing the resin sliding surface is a metal surface. The grease composition for resin lubrication according to claim 1 or 2.

4. A resin sliding member having a resin sliding surface to which the grease composition for resin lubrication according to any one of claims 1 to 3 is applied.

5. 5. The resin sliding member according to claim 4, which is a slide switch.

6. The resin sliding member according to claim 4 , which is a gear device.

7. 4. A resin-metal sliding member having a resin sliding surface to which the grease composition for resin lubrication according to claim 1 is applied, and a metal mating surface facing the sliding surface.

8. 8. The resin-metal sliding member according to claim 7, which is a slide switch.

9. The resin-metal sliding member according to claim 7 , which is a gear device.

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