Composition for lubricating coating film and lubricating coating film

Abstract

To provide a composition for a lubricating coating film and a lubricating coating film that use an alternative material to PFAS and have high lubricity.SOLUTION: A composition for a lubricating coating film comprises a first polyethylene having a weight-average molecular weight of 1,000,000 or more and a second polyethylene having a density of 0.94 g / cm3 or more. A total amount of the first polyethylene and the second polyethylene is 15 mass% or more to 40 mass% or less with respect to a total amount of the composition for a lubricating coating film.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a composition for a lubricating coating film and a lubricating coating film.

Background Art

[0002] In a sliding device having a sliding surface, from the viewpoint of reducing the friction coefficient during sliding, it is preferable to provide a lubricating coating film for improving lubricity on the sliding surface.

[0003] For example, Patent Document 1 discloses a coating composition for a lubricating film containing a phenol resin, an epoxy resin, and a solid lubricant.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in recent years, regulations on per- and polyfluoroalkyl substances (PFAS) have been considered and implemented in various countries around the world. Therefore, there is a risk that PFAS such as polytetrafluoroethylene (PTFE), which has conventionally been used in lubricating coating films and the like for the purpose of a low friction coefficient, may become unavailable or its usage amount may be restricted. Thus, studies have been made on alternative materials for PFAS in lubricating coating films. It is desired that a lubricating coating film using an alternative material for PFAS has high lubricity, similarly to a lubricating coating film using PFAS.

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to provide a composition for a lubricating coating film, a lubricating coating film, and the like that use an alternative material for PFAS and have high lubricity.

Means for Solving the Problems

[0007] The inventors of the present invention have conducted intensive studies to solve the above problems. As a result, a composition for a lubricating coating film containing a first polyethylene having a weight average molecular weight of 1,000,000 or more and a second polyethylene having a density of 0.94 g / cm 3 or more, wherein the total amount of the first polyethylene and the second polyethylene is 15% by mass or more and 40% by mass or less based on the total amount of the composition for a lubricating coating film, has been found to be able to solve the above problems, and the present invention has been completed.

[0008] That is, the present invention includes the following aspects. [1] A composition for a lubricating coating film containing a first polyethylene having a weight average molecular weight of 1,000,000 or more and a second polyethylene having a density of 0.94 g / cm 3 or more, wherein the total amount of the first polyethylene and the second polyethylene is 15% by mass or more and 40% by mass or less based on the total amount of the composition for a lubricating coating film. Composition for a lubricating coating film. [2] The median diameter of the first polyethylene is 70 μm or less, and the median diameter of the second polyethylene is 70 μm or less. The composition for a lubricating coating film according to [1]. [3] The composition for a lubricating coating film according to [1] or [2], containing 5% by mass or more and 10% by mass or less of an amide-modified polyethylene wax based on the total amount of the composition for a lubricating coating film. The composition for a lubricating coating film according to [1] or [2]. [4] The median diameter of the amide-modified polyethylene wax is 70 μm or less. The composition for a lubricating coating film according to [3]. [5] The composition for a lubricating coating film according to any one of [1] to [4], containing 50% by mass or more and 70% by mass or less of an engineering plastic based on the total amount of the composition for a lubricating coating film. The composition for a lubricating coating film according to any one of [1] to [4]. [6] Substantially free of organic fluorine compounds. The composition for a lubricating coating film according to any one of [1] to [5]. [7] A lubricating coating film containing the composition for a lubricating coating film according to any one of [1] to [6], wherein the first polyethylene and the second polyethylene are present in an island-in-sea state on the surface of the lubricating coating film; Lubricating coating film. [8] A method for producing a lubricating coating film, including a step of producing a lubricating coating film using the composition for a lubricating coating film according to any one of [1] to [6], wherein the step of producing the lubricating coating film includes a firing step of firing the composition for a lubricating coating film at a temperature equal to or higher than the melting points of the first polyethylene and the second polyethylene. Method for producing a lubricating coating film. [Advantages of the Invention]

[0009] According to the present invention, it is possible to provide a composition for a lubricating coating film, a lubricating coating film, etc., which use an alternative material for PFAS and have high lubricity. [Brief Description of the Drawings]

[0010]

Figure 1

Figure 2

Figure 3

[0011] Hereinafter, embodiments of the present invention (hereinafter referred to as "the present embodiment") will be described in detail, but the present invention is not limited thereto, and various modifications are possible without departing from the gist thereof.

[0012] 1. Composition for lubricating coating film 1.1. Polyethylene The composition for a lubricating coating film of this embodiment contains a plurality of types of polyethylene. The content of polyethylene with respect to the total amount of the composition for a lubricating coating film is preferably 0.2 to 100% by mass, 0.5 to 95% by mass, 1 to 90% by mass, 2 to 80% by mass, 3 to 70% by mass, 4 to 60% by mass, 5 to 55% by mass, 10 to 50% by mass, 15 to 40% by mass. The lower limit of the content of polyethylene with respect to the total amount of the composition for a lubricating coating film may be any of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60% by mass. The upper limit of the content of polyethylene with respect to the total amount of the composition for a lubricating coating film may be any of 100, 95, 90, 85, 80, 75, 70, 65, 60% by mass. Further, the above lower limit and the above upper limit may be combined in any combination.

[0013] The polyethylene contained in the composition for a lubricating coating film of this embodiment is not particularly limited. For example, it includes one or more selected from the group consisting of ultra-high molecular weight polyethylene (UHMW-PE), high density polyethylene (HDPE), medium density polyethylene (MDPE), linear low density polyethylene (LLDPE), low density polyethylene (LDPE), very low density polyethylene (VLDPE), and oxidized polyethylene, or is one or more selected from this group. Note that UHMW-PE is polyethylene having a weight average molecular weight of 1,000,000 or more. HDPE is polyethylene having a density of 0.94 g / cm 3 or more. MDPE is polyethylene having a density of 0.93 g / cm 3 or more and less than 0.94 g / cm 3 LDPE is polyethylene having a density of 0.91 g / cm 3 or more and less than 0.93 g / cm 3 VLDPE is polyethylene having a density of less than 0.91 g / cm 3 LLDPE is polyethylene having a density of 0.910 g / cm 3 or more and 0.925 g / cm 3 or less. Note that the weight average molecular weight is determined, for example, by the GPC measurement method in terms of polystyrene conversion.

[0014] The composition for a lubricating coating film of this embodiment includes a first polyethylene having a weight average molecular weight of 1,000,000 or more and a second polyethylene having a density of 0.94 g / cm 3 or more, and the total amount of the first polyethylene and the second polyethylene is 15% by mass or more and 40% by mass or less with respect to the total amount of the composition for the lubricating coating film. The first polyethylene is UHMW-PE and the second polyethylene is HDPE.

[0015] Polyethylene has weak intermolecular forces and tends to have a low coefficient of friction. Among them, HDPE has a lower coefficient of friction, while its molecular weight is small and its wear resistance tends to be low. Also, UHMW-PE tends to have a higher coefficient of friction than HDPE, while its molecular weight is large and its wear resistance is high. The composition for a lubricating coating film of the present embodiment contains HDPE and UHMW-PE. When the composition is fired at a temperature equal to or higher than the melting points of both polyethylenes to produce a lubricating coating film, both polyethylenes melt and mix in the lubricating coating film. When melted, HDPE has high fluidity due to its low molecular weight, and UHMW-PE has low fluidity due to its high molecular weight. Therefore, HDPE flows so as to wrap around UHMW-PE. Therefore, in the lubricating coating film formed by solidifying the composition in a molten state, the region containing HDPE (hereinafter also referred to as the "HDPE region") tends to cover the region containing UHMW-PE (hereinafter also referred to as the "UHMW-PE region"). As a result, HDPE with a lower coefficient of friction is likely to appear on the surface of the lubricating coating film. When a member is slid on the surface of the lubricating coating film, the coefficient of friction becomes small. That is, the lubricating coating film of the present embodiment is excellent in lubricity. Further, in the lubricating coating film provided on the base material, since a UHMW-PE region with higher wear resistance exists inside the HDPE region (on the base material side), even when the member is repeatedly slid on the lubricating coating film, the HDPE region is less likely to peel off. Also, even after the HDPE region peels off, since the UHMW-PE region appears on the surface that slides with the member of the lubricating coating film, a decrease in the lubricity of the lubricating coating film can be suppressed. That is, the lubricating coating film of the present embodiment tends to be excellent in lubricating durability. Also, in the above lubricating coating film, the UHMW-PE regions are scattered, and there tends to be an HDPE region between the regions. In this way, the UHMW-PE regions are bonded to each other via the HDPE region, and the UHMW-PE region and the HDPE region are bonded to each other in the lubricating coating film. Even when the member is repeatedly slid on the lubricating coating film, the UHMW-PE region and the HDPE region are less likely to peel off, and the lubricity of the lubricating coating film tends to be maintained. That is, the lubricating coating film of the present embodiment tends to be excellent in lubricity and lubricating durability.

[0016] In addition, when the total amount of the first polyethylene and the second polyethylene is 15% by mass or more and 40% by mass or less based on the total amount of the lubricating coating composition, the lubricity and lubrication durability of the lubricating coating tend to be further improved.

[0017] The lubricating coating composition of this embodiment preferably does not substantially contain PFAS, and preferably does not contain PFAS. Although not particularly limited, not substantially containing PFAS means that, for example, the content of PFAS is 0 to 2.0% by mass, 0 to 1.5% by mass, 0 to 1.0% by mass, 0 to 0.5% by mass, and 0 to 0.1% by mass based on the total amount of the lubricating coating composition. When the lubricating coating composition does not substantially contain PFAS or does not contain PFAS, the lubrication durability tends to improve and the environmental compatibility tends to improve. PFAS is not particularly limited as long as it is an organic fluorine compound in which some or all of the hydrogens bonded to carbon in a hydrocarbon are substituted with fluorine. Examples include polyfluoroalkyl compounds such as polytetrafluoroethylene (PTFE); perfluoroalkyl compounds such as perfluorooctanesulfonic acid and perfluorooctanoic acid.

[0018] The total amount of the first polyethylene and the second polyethylene is preferably 17.5 to 35.0% by mass, and 20.0 to 30.0% by mass based on the total amount of the lubricating coating composition. When the total amount of the first polyethylene and the second polyethylene is within the above range, the lubricity and lubrication durability of the lubricating coating tend to be further improved.

[0019] The content of the first polyethylene is preferably 2.5 to 20.0% by mass, 5.0 to 15.0% by mass, and 7.5 to 12.5% by mass based on the total amount of the lubricating coating composition. When the content of the first polyethylene is within the above range, the lubricity and lubrication durability of the lubricating coating tend to be further improved.

[0020] The content of the second polyethylene is preferably 10.0 to 30.0% by mass, 12.5 to 27.5% by mass, and 15.0 to 25.0% by mass with respect to the total amount of the lubricating coating composition. When the content of the second polyethylene is within the above range, the lubricity and lubrication durability of the lubricating coating tend to be further improved.

[0021] The ratio (W2 / W1) of the content (W2) of the second polyethylene to the content (W1) of the first polyethylene in the lubricating coating composition is preferably 1.1 to 3.0, 1.3 to 2.8, and 1.5 to 2.5. When the ratio is within the above range, the lubricity and lubrication durability of the lubricating coating tend to be further improved.

[0022] The weight average molecular weight of the first polyethylene is preferably 1 million to 7 million, 1.1 million to 6 million, 1.2 million to 5 million, 1.3 million to 4 million, and 1.5 million to 3 million. When the weight average molecular weight of the first polyethylene is within the above range, the lubricity and lubrication durability of the lubricating coating tend to be further improved.

[0023] The density of the second polyethylene is preferably 0.94 to 1.10 g / cm 3 and 0.95 to 1.00 g / cm 3 When the density of the second polyethylene is within the above range, the lubricity and lubrication durability of the lubricating coating tend to be further improved.

[0024] The melting point of the first polyethylene is preferably 110 to 200 °C, 115 to 175 °C, and 120 to 150 °C. When the melting point of the first polyethylene is within the above range, the lubricating coating composition can tend to be melted at an appropriate temperature to obtain a lubricating coating.

[0025] The melting point of the second polyethylene is preferably 100 to 150 °C, 105 to 140 °C, or 110 to 130 °C. When the melting point of the second polyethylene is within the above range, the composition for the lubricating coating film tends to be melted at an appropriate temperature to obtain the lubricating coating film.

[0026] The first polyethylene is preferably in the form of solid particles, and its median diameter (D50) is preferably 70 μm or less, 1 to 70 μm, 2 to 50 μm, 3 to 25 μm, or 5 to 20 μm. When the median diameter (D50) of the first polyethylene is within the above range, the lubricity of the lubricating coating film tends to be further improved.

[0027] The second polyethylene is preferably in the form of solid particles, and its median diameter (D50) is preferably 70 μm or less, 1 to 70 μm, 2 to 50 μm, 3 to 25 μm, or 5 to 20 μm. When the median diameter (D50) of the second polyethylene is within the above range, the lubricity of the lubricating coating film tends to be further improved.

[0028] The median diameter (D50) is the particle diameter corresponding to 50% cumulative degree in the particle size distribution measured by the laser diffraction / scattering method, and is defined as the particle diameter at which the number of particles with a particle diameter larger than the median diameter is the same as the number of particles with a particle diameter smaller than the median diameter.

[0029] The median diameter is not particularly limited, but can be measured, for example, using a laser diffraction type particle size distribution measuring device "MT3300EXII" manufactured by Microtrac.

[0030] 1.2. Wax The composition for a lubricating coating film of the present embodiment may contain substances other than the first polyethylene and the second polyethylene. Such substances are not particularly limited, and examples thereof include waxes. The wax is not particularly limited, and examples thereof include one or more selected from the group consisting of amide-modified polyethylene wax, carboxyl-modified polyethylene wax, hydroxyl-modified polyethylene wax, polyolefin wax (solid paraffin), monoamide, and bisamide. Among these, it is preferable that the composition for a lubricating coating film contains amide-modified polyethylene wax. Note that the amide-modified polyethylene wax means a polyethylene wax in which hydrogen of polyethylene is substituted with an amide group.

[0031] The content of the wax is not particularly limited. For example, it is 15% by mass or less, 0 to 15% by mass, 1 to 14% by mass, 2 to 13% by mass, 3 to 12% by mass, 4 to 11% by mass, or 5 to 10% by mass with respect to the total amount of the composition for a lubricating coating film. The composition for a lubricating coating film may not contain wax. When the composition for a lubricating coating film of the present embodiment contains wax, the lubricity of the lubricating coating film tends to be further improved.

[0032] The wax is preferably in the form of solid particles, and its median diameter is preferably 70 μm or less, 1 to 70 μm, 2 to 50 μm, 3 to 25 μm, 4 to 20 μm, or 5 to 10 μm. When the median diameter of the wax is within the above range, the lubricity of the lubricating coating film tends to be further improved.

[0033] 1.3. Binder The lubricating coating composition of this embodiment may contain a binder. Examples of the binder include one or more selected from the group consisting of engineering plastics such as epoxy resin, melamine resin, triazine resin, phenol resin, polyamideimide (PAI), polyethersulfone (PES), and polyimide (PI). Here, the engineering plastic means a resin having a heat resistance temperature of 100 °C or higher, a tensile strength of 49 MPa or higher, and a flexural modulus of 2.4 GPa or higher. The content of the binder is not particularly limited. For example, it is 10 to 80% by mass, 20 to 75% by mass, 30 to 70% by mass, 40 to 65% by mass, or 50 to 60% by mass based on the total amount of the lubricating coating composition. Alternatively, the content of the binder is, for example, 50 to 70% by mass based on the total amount of the lubricating coating composition. When the content of the binder is within the above range, the lubricity of the lubricating coating tends to be further improved.

[0034] When the lubricating coating composition of this embodiment contains a binder, it preferably contains an epoxy resin or a phenol resin which is an engineering plastic, and more preferably contains an epoxy resin and a phenol resin which are engineering plastics.

[0035] 1.4. Other Additives The composition for a lubricating coating film of the present embodiment may contain other additives other than the above substances. The other additives are not particularly limited, and examples thereof include molybdenum disulfide, graphite, tungsten disulfide, boron nitride, calcium carbonate, talc, mica, melamine cyanurate (MCA), metal oxides, inorganic oxides, and oils (polyalphaolefin (PAO), silicone, polyalkylene glycol (PAG), ester, mineral oil). The content of the additive is not particularly limited, but for example, it is 30% by mass or less, 0 to 30% by mass, 1 to 25% by mass, 2 to 22% by mass, 3 to 19% by mass, 4 to 17% by mass, 5 to 15% by mass with respect to the total amount of the composition for a lubricating coating film. Note that by including molybdenum disulfide or the like, the lubricity of the lubricating coating film tends to be further improved.

[0036] 2. Lubricating Coating Film The lubricating coating film of the present embodiment is a coating film containing the composition for a lubricating coating film of the above-described present embodiment. Note that the lubricating coating film is a coating film for imparting lubricity to the base material on the side where the coating film is provided.

[0037] The lubricating coating film of the present embodiment is not particularly limited. For example, it is obtained by including the composition for a lubricating coating film of the present embodiment and firing at a temperature higher than the melting point of all the polyethylene contained in the composition for a lubricating coating film.

[0038] The lubricating coating film of the present embodiment contains a plurality of types of polyethylene. The content of polyethylene with respect to the total mass of the lubricating coating film is preferably 0.2 to 100% by mass, 0.5 to 95% by mass, 1 to 90% by mass, 2 to 80% by mass, 3 to 70% by mass, 4 to 60% by mass, 5 to 55% by mass, 10 to 50% by mass, 15 to 40% by mass. The lower limit of the content of polyethylene with respect to the total mass of the lubricating coating film may be any of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60% by mass. The upper limit of the content of polyethylene with respect to the total mass of the lubricating coating film may be any of 100, 95, 90, 85, 80, 75, 70, 65, 60% by mass. Further, the above lower limit and the above upper limit may be combined in any combination.

[0039] The polyethylene contained in the lubricating coating film of the present embodiment includes ultra-high molecular weight polyethylene (UHMW-PE, the first polyethylene) and high density polyethylene (HDPE, the second polyethylene). Further, the polyethylene contained in the lubricating coating film is not particularly limited, and may include, for example, one or more selected from the group consisting of medium density polyethylene (MDPE), linear low density polyethylene (LLDPE), low density polyethylene (LDPE), very low density polyethylene (VLDPE), and oxidized polyethylene.

[0040] The lubricating coating film of the present embodiment preferably contains substantially no PFAS and preferably contains no PFAS. Substantially containing no PFAS is not particularly limited, but for example, the content of PFAS is 0 to 2.0% by mass, 0 to 1.5% by mass, 0 to 1.0% by mass, 0 to 0.5% by mass, 0 to 0.1% by mass with respect to the total amount of the lubricating coating film. By the lubricating coating film substantially containing no PFAS or containing no PFAS, the lubricating durability tends to improve and the environmental compatibility tends to improve. PFAS is an organic fluorine compound which is an organic compound in which some or all of the hydrogen atoms bonded to carbon in a hydrocarbon are substituted with fluorine. It is not particularly limited, but examples include polyfluoroalkyl compounds such as polytetrafluoroethylene (PTFE); perfluoroalkyl compounds such as perfluorooctanesulfonic acid and perfluorooctanoic acid, etc.

[0041] The total amount of the first polyethylene and the second polyethylene in the lubricating coating film is preferably 15.0 to 40.0% by mass, 17.5 to 35.0% by mass, 20.0 to 30.0% by mass with respect to the total amount of the lubricating coating film. When the total amount of the first polyethylene and the second polyethylene is within the above range, the lubricity and lubricating durability of the lubricating coating film tend to be further improved.

[0042] The content of the first polyethylene in the lubricating coating film is preferably 2.5 to 20.0% by mass, 5.0 to 15.0% by mass, 7.5 to 12.5% by mass with respect to the total amount of the lubricating coating film. When the content of the first polyethylene is within the above range, the lubricity and lubricating durability of the lubricating coating film tend to be further improved.

[0043] The content of the second polyethylene in the lubricating coating film is preferably 10.0 to 30.0% by mass, 12.5 to 27.5% by mass, 15.0 to 25.0% by mass with respect to the total amount of the lubricating coating film. When the content of the second polyethylene is within the above range, the lubricity and lubricating durability of the lubricating coating film tend to be further improved.

[0044] In the lubricating coating film, the ratio (W2 / W1) of the content (W2) of the second polyethylene to the content (W1) of the first polyethylene is preferably 1.1 to 3.0, 1.3 to 2.8, and 1.5 to 2.5. When the ratio is within the above range, the lubricity and lubrication durability of the lubricating coating film tend to be further improved.

[0045] The lubricating coating film of the present embodiment may contain substances other than the first polyethylene and the second polyethylene. Such substances are not particularly limited, and examples include wax. The wax is not particularly limited, and examples include one or more selected from the group consisting of amide-modified polyethylene wax, carboxyl-modified polyethylene wax, hydroxyl-modified polyethylene wax, polyolefin wax (solid paraffin), monoamide, and bisamide. Among these, it is preferable that the lubricating coating film contains amide-modified polyethylene wax. The content of the wax is not particularly limited, and for example, it is 15% by mass or less, 0 to 15% by mass, 1 to 14% by mass, 2 to 13% by mass, 3 to 12% by mass, 4 to 11% by mass, or 5 to 10% by mass with respect to the total mass of the lubricating coating film. The lubricating coating film may not contain wax.

[0046] The lubricating coating film of the present embodiment may contain a binder. Examples of the binder include one or more selected from the group consisting of engineering plastics such as epoxy resin, melamine resin, triazine resin, phenol resin, polyamideimide (PAI), polyethersulfone (PES), and polyimide (PI). The content of the binder is not particularly limited, and for example, it is 10 to 80% by mass, 20 to 75% by mass, 30 to 70% by mass, 40 to 65% by mass, or 50 to 60% by mass with respect to the total mass of the lubricating coating film. Alternatively, the content of the binder is, for example, 50 to 70% by mass with respect to the total amount of the lubricating coating film.

[0047] When the lubricating coating film of the present embodiment contains a binder, it preferably contains an epoxy resin or a phenolic resin, which is an engineering plastic, and more preferably contains an epoxy resin and a phenolic resin, which are engineering plastics.

[0048] The lubricating coating film of the present embodiment may contain other additives other than the above substances. The other additives are not particularly limited, and examples thereof include one or more selected from the group consisting of molybdenum disulfide, graphite, tungsten disulfide, boron nitride, calcium carbonate, talc, mica, MCA, metal oxides, inorganic oxides, and oils (PAO, silicone, PAG, ester, mineral oil). The content of the additive is not particularly limited, but for example, it is 30% by mass or less, 0 to 30% by mass, 1 to 25% by mass, 2 to 22% by mass, 3 to 19% by mass, 4 to 17% by mass, or 5 to 15% by mass with respect to the total mass of the lubricating coating film. Note that by including molybdenum disulfide or the like, the lubricity of the lubricating coating film tends to be further improved.

[0049] The lubricating coating film of the present embodiment may contain a plurality of the above-described polyethylene. Further, the lubricating coating film of the present embodiment may be a coating film that contains a plurality of the above-described polyethylene and is fired at a temperature higher than their melting points.

[0050] The lubricating coating film of the present embodiment may contain UHMW-PE, HDPE, and amide-modified polyethylene wax. Further, the lubricating coating film of the present embodiment is not particularly limited, and for example, it may be a coating film that contains UHMW-PE, HDPE, and amide-modified polyethylene wax and is fired at a temperature higher than the melting points of UHMW-PE, HDPE, and amide-modified polyethylene wax.

[0051] In the lubricating coating film of the present embodiment, polyethylene may be present in an island-in-sea structure on the surface of the coating film. Further, in the lubricating coating film of the present embodiment, UHMW-PE and HDPE may be present in an island-in-sea structure on the surface of the coating film. The lubricating coating film of the present embodiment contains the above-described composition for a lubricating coating film of the present embodiment, and the first polyethylene and the second polyethylene may be present in an island-in-sea structure on the surface of the lubricating coating film. This lubricating coating film tends to have better lubricity. In this case, the region corresponding to the island is, for example, the region where the first polyethylene and the second polyethylene are present, and the region corresponding to the sea is the other region (for example, the region where the binder is present).

[0052] 3. Method for manufacturing lubricating coating film The method for manufacturing a lubricating coating film of the present embodiment is a method for manufacturing a lubricating coating film including a step of manufacturing a lubricating coating film using the composition for a lubricating coating film of the present embodiment, wherein the step of manufacturing the lubricating coating film includes a firing step of firing the composition for a lubricating coating film at a temperature equal to or higher than the melting points of the first polyethylene and the second polyethylene. By firing the composition for a lubricating coating film at a temperature equal to or higher than the melting points of the first polyethylene and the second polyethylene, the first polyethylene and the second polyethylene melt and mix together. Then, the lubricating coating film obtained by cooling and solidifying after firing tends to be excellent in lubricity and lubricating durability. Further, on the surface of the lubricating coating film, the first polyethylene and the second polyethylene tend to be present in an island-in-sea structure. That is, it tends to be more excellent in lubricity and lubricating durability.

[0053] The composition for a lubricating coating film and the lubricating coating film of the present embodiment tend to be able to provide a coating film with a low friction coefficient even without containing PFAS. Further, the composition for a lubricating coating film and the lubricating coating film of the present embodiment tend to be excellent in lubricating durability (friction resistance) even without containing PFAS. Further, the composition for a lubricating coating film and the lubricating coating film of the present embodiment tend to be excellent in any one or more of rust prevention, water repellency, and oil repellency even without containing PFAS.

[0054] FIG. 1 shows an example of a cross-sectional view when a lubricating coating film is provided on a base material. In FIG. 1, a lubricating coating film 100 is provided on a base material 200, and the lubricating coating film 100 includes a mixture 130 of polyethylene and wax, an additive 120, and a binder 110. Only a part of the polyethylene and wax is mixed, and the rest may exist independently or may exist as a completely mixed mixture 130. In FIG. 1, the first polyethylene and the second polyethylene exist in an island-in-sea form on the surface of the lubricating coating film 100. Specifically, on the surface of the lubricating coating film 100, the region where the mixture 130 exists is an island, and the region where the binder 110 exists is the sea.

[0055] The lubricating coating film of this embodiment includes the following aspects. 1. A lubricating coating film containing multiple types of polyethylene (UHMW-PE, HDPE) and fired at a temperature higher than their melting points. 2. A lubricating coating film containing UHMW-PE, HDPE, and amide-modified polyethylene wax and fired at a temperature higher than their melting points. 3. A lubricating coating film having the composition described in FIG. 2. 4. A lubricating coating film in which dissolved UHMW-PE and HDPE exist in an island-in-sea form on the coating film surface. 5. A lubricating coating film containing, as wax, one or more selected from the group consisting of amide-modified polyethylene wax, carboxyl-modified polyethylene wax, hydroxyl-modified polyethylene wax, polyolefin wax (solid paraffin), monoamide, and bisamide. 6. A lubricating coating film containing, as an additive, one or more selected from the group consisting of molybdenum disulfide, graphite, tungsten disulfide, boron nitride, calcium carbonate, talc, mica, MCA, metal oxides, inorganic oxides, and oils (PAO, silicone, PAG, ester, mineral oil). 7. A lubricating coating film containing, as a binder, one or more selected from the group consisting of engineering plastics (epoxy resin, melamine resin, triazine resin, phenol resin, PAI, PES, PI, etc.).

[0056] 4. Sliding device The composition for a lubricating coating film of the present embodiment is applied onto the surface of a base material to form a lubricating coating film. The base material has a configuration in which a member slides on its surface. The material of the base material is not particularly limited, and examples thereof include synthetic resins such as phenolic resin, melamine resin, urea resin, alkyd resin, epoxy resin, polyester resin, polyurethane resin, polyethylene resin, polypropylene resin, polystyrene resin, polyvinyl acetate resin, polyurethane resin, polylactic acid resin, Teflon resin, acrylonitrile-butadiene-styrene resin, acrylonitrile-styrene resin, acrylic resin, polyvinyl chloride resin, polyamide resin, glass fiber reinforced polyamide resin, polyacetal resin, polycarbonate resin, and modified polyphenylene ether resin, as well as metals such as aluminum, magnesium, iron, copper, tin, zinc, lead and their alloys, and inorganic materials such as glass.

[0057] The material of the member is not particularly limited, and examples thereof include the same materials as those exemplified for the base material.

[0058] The base material and the member may be made of the same material as each other, or may be made of different materials.

[0059] The sliding device having the base material and the member, and in which the member slides on the base material is not particularly limited, and examples thereof include a door lock mechanism, a window regulator, a seat rail, a sunroof, a suspension, a brake, a seat belt mechanism, or a gear portion of a steering system.

Examples

[0060] Hereinafter, the present invention will be described more specifically using examples. The present invention is not limited by the following examples. Also, unless otherwise specified, it was carried out at room temperature (25 ° C) and 1 atmosphere.

[0061] The compounds were mixed and stirred so as to have the composition shown in FIG. 3 to obtain a composition for a lubricating coating film for each experimental example. Thereafter, the composition for a lubricating coating film for each experimental example was applied onto the base material and then baked at 200 ° C. to obtain a lubricating coating film for each experimental example.

[0062] The abbreviations and product components shown in Figure 3 are as follows. The blank spaces in Figure 3 indicate that the corresponding components were not used. Binder: Epoxy resin / Phenolic resin (Engineering plastic) Additive: Molybdenum disulfide powder UHMW-PE: Molecular weight: 1.8 million, Melting point: 136 °C, Median diameter: 10 μm HDPE A: Density: 0.94 or more, Melting point: 125 °C HDPE B: Density: 1.06, Melting point: 125 °C HDPE C: Density: 0.98, Melting point: 125 °C HDPE D: Density: 0.97, Melting point: 122 °C, Median diameter: 8 μm PA12 A: Polyamide 12 powder, Melting point: 170 °C PA12 B: Polyamide 12 powder, Melting point: 170 °C PA12 C: Polyamide 12 powder, Melting point: 177 °C PA12 D: Polyamide 12 powder, Melting point: 177 °C Biopolymer A: Modified biopolymer, Melting point: 175 °C Biopolymer B: Modified biopolymer, Melting point: 175 °C Amide-modified polyethylene wax: Median diameter: 6 μm

[0063] In the table of Figure 3, μs represents the coefficient of static friction and μd represents the coefficient of kinetic friction. The coefficients of static friction and kinetic friction were measured under the following conditions. Equipment used: TRIBOGEAR Type14 special manufactured by Shin-Tong Science Co., Ltd. Test piece: A lubricating coating film of each experimental example was formed with a thickness of 20 μm on a SUS301 test piece (thickness t = 0.3 mm). Counter material: SPCC-SB flat plate 25 × 25 mm Speed: 0.4 mm / sec Stroke width: 5 mm (The counter material was reciprocated with this stroke width on the lubricating coating film of each experimental example formed on the base material.) Load: 24 N (Surface pressure: 0.0384 MPa) Evaluation: Coefficient of static friction and coefficient of kinetic friction at the 5th sliding

[0064] μs was evaluated based on the following evaluation criteria. Evaluation A is the best, and the lubricating coatings are excellent in the order of A, B, C, and D. Lubricating coatings with an evaluation of B or higher can be suitably used in a sliding device. A: μs ≦ 0.10 B: 0.10 < μs ≦ 0.15 C: 0.15 < μs ≦ 0.30 D: 0.30 < μs

[0065] μd was evaluated based on the following evaluation criteria. Evaluation A is the best, and the lubricating coatings are excellent in the order of A, B, C, and D. Lubricating coatings with an evaluation of B or higher can be suitably used in a sliding device. A: μd ≦ 0.10 B: 0.10 < μd ≦ 0.15 C: 0.15 < μd ≦ 0.30 D: 0.30 < μd

[0066] For the lubricating coatings prepared using the lubricating coating composition of Experimental Example 1 and the lubricating coatings prepared using the lubricating coating compositions of Experimental Examples 12 to 15, the lubricating durability was evaluated. Specifically, the depth of wear (μm) of the test piece was measured under the same conditions as the measurement conditions of the coefficient of static friction and the coefficient of kinetic friction, except that the sliding was performed 20,000 times.

[0067] The wear depth in the lubricating coatings prepared using the lubricating coating compositions of Experimental Examples 12 to 15 was smaller than the wear depth in the lubricating coatings prepared using the lubricating coating composition of Experimental Example 1. That is, it was found that the lubricating coatings prepared using the lubricating coating compositions of Experimental Examples 12 to 15 had excellent lubricating durability.

[0068] In addition, when the cross-section of the lubricating coatings prepared using the lubricating coating compositions of Experimental Examples 12 to 15 was observed with a scanning electron microscope (SEM), it was confirmed that the first polyethylene and the second polyethylene were present in an island shape on the surface of the lubricating coating.

Explanation of Signs

[0069] 100… Lubricating coating film, 110… Binder, 120… Additive, 130… Mixture of polyethylene and wax, 200… Base material

Claims

1. A first polyethylene having a weight average molecular weight of 1 million or more and a density of 0.94 g / cm 3 A lubricating coating composition comprising the above second polyethylene, the total amount of the first polyethylene and the second polyethylene is 15% by mass or more and 40% by mass or less based on the total amount of the lubricating coating composition; Composition for lubricating coatings.

2. The first polyethylene has a median diameter of 70 μm or less, The median diameter of the second polyethylene is 70 μm or less. The lubricating coating composition of claim 1.

3. The lubricating coating composition contains 5% by mass or more and 10% by mass or less of an amide-modified polyethylene wax based on the total amount of the lubricating coating composition. The lubricating coating composition of claim 1.

4. The median diameter of the amide-modified polyethylene wax is 70 μm or less. The lubricating coating composition of claim 3.

5. The lubricating coating composition contains engineering plastics in an amount of 50% by mass or more and 70% by mass or less based on the total amount of the lubricating coating composition. The lubricating coating composition of claim 1.

6. Substantially free of organic fluorine compounds; The lubricating coating composition of claim 1.

7. A lubricating coating comprising the lubricating coating composition according to any one of claims 1 to 6, the first polyethylene and the second polyethylene are present in an island-like form on the surface of the lubricating coating; Lubricating coating.

8. A method for producing a lubricating coating, comprising a step of producing a lubricating coating using the lubricating coating composition according to any one of claims 1 to 6, wherein the step of producing the lubricating coating comprises a baking step of baking the lubricating coating composition at a temperature equal to or higher than the melting points of the first polyethylene and the second polyethylene. A method for producing a lubricating coating.

Images