Composition for lubricating coating film and lubricating coating film

Abstract

The purpose of the present invention is to provide: a composition for lubricating coating films, which uses a PFAS substitute material and has high lubricity; a lubricating coating film; and the like. The present invention provides a composition for a lubricating coating film comprising 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, the total amount of the first polyethylene and the second polyethylene being 15-40 mass% relative to the total amount of the composition for a lubricating coating film.

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 coating film containing a phenolic resin, an epoxy resin, and a solid lubricant.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2017-514928. Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] However, in recent years, restrictions on per- and polyfluoroalkyl substances (PFAS) have been studied and implemented in various countries around the world. Therefore, conventionally, it may not be possible to use PFAS such as polytetrafluoroethylene (PTFE) used in lubricating coating films for the purpose of a low friction coefficient, or the amount of its use may be restricted. Therefore, research has been conducted on PFAS alternative materials in lubricating coating films. It is desired that a lubricating coating film using a PFAS alternative material has high lubricity like a lubricating coating film using PFAS.

[0009] The present invention has been completed in view of the above circumstances, and an object thereof is to provide a composition for a lubricating coating film, a lubricating coating film, etc. that use a PFAS alternative material and have high lubricity.

[0010] Means for Solving the Problems

[0011] The present inventors conducted intensive studies to solve the above problems. As a result, a composition for a lubricating coating film was found. The composition for a lubricating coating film contains 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. The total amount of the first polyethylene and the second polyethylene is 15% by mass or more and 40% by mass or less relative to the total amount of the composition for a lubricating coating film, and it can solve the above problems, thereby completing the present invention.

[0012] That is, the present invention includes the following aspects.

[0013] [1] A composition for a lubricating coating film, comprising:

[0014] A first polyethylene having a weight average molecular weight of 1,000,000 or more; and

[0015] A second polyethylene having a density of 0.94 g / cm 3 or more,

[0016] The total amount of the first polyethylene and the second polyethylene is 15% by mass or more and 40% by mass or less relative to the total amount of the lubricating coating film composition.

[0017] [2] The lubricating coating film composition according to [1], wherein

[0018] The median particle size of the first polyethylene is 70 μm or less,

[0019] The median particle size of the second polyethylene is 70 μm or less.

[0020] [3] The lubricating coating film composition according to [1] or [2], wherein

[0021] 5% by mass or more and 10% by mass or less of an amide-modified polyethylene wax is contained relative to the total amount of the lubricating coating film composition.

[0022] [4] The lubricating coating film composition according to [3], wherein

[0023] The median particle size of the amide-modified polyethylene wax is 70 μm or less.

[0024] [5] The lubricating coating film composition according to any one of [1] to [4], wherein

[0025] 50% by mass or more and 70% by mass or less of an engineering plastic is contained relative to the total amount of the lubricating coating film composition.

[0026] [6] The lubricating coating film composition according to any one of [1] to [5], wherein substantially no organic fluorine compound is contained.

[0027] [7] A lubricating coating film comprising the lubricating coating film composition according to any one of [1] to [6],

[0028] The first polyethylene and the second polyethylene are present in an island-like form on the surface of the lubricating coating film.

[0029] [8] A method for manufacturing a lubricating coating film, which includes a step of manufacturing a lubricating coating film using the lubricating coating film composition according to any one of [1] to [6],

[0030] The step of manufacturing the lubricating coating film includes a firing step of firing the lubricating coating film composition at a temperature above the melting points of the first polyethylene and the second polyethylene.

[0031] Advantages of the Invention

[0032] According to the present invention, it is possible to provide a lubricating coating film composition and a lubricating coating film that use PFAS alternative materials and have high lubricity, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a cross-sectional view in the case where a lubricating coating film is provided on a base material.

[0034] Figure 2 It is a diagram showing an example of the composition of the lubricating coating film of the present embodiment.

[0035] Figure 3 It is a diagram showing the results of the examples. DETAILED DESCRIPTION OF THE INVENTION

[0036] Hereinafter, embodiments of the present invention (hereinafter referred to as "the present embodiment") will be described in detail. However, the present invention is not limited thereto, and various modifications can be made without departing from the gist thereof.

[0037] 1. Lubricating Coating Film Composition

[0038] 1.1. Polyethylene

[0039] The lubricating coating film composition of the present embodiment contains various polyethylenes. The content of polyethylene 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, relative to the total amount of the lubricating coating film composition. The lower limit value of the content of polyethylene relative to the total amount of the lubricating coating film composition can be any one 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 value of the content of polyethylene relative to the total amount of the lubricating coating film composition can be any one of 100, 95, 90, 85, 80, 75, 70, 65, 60% by mass. In addition, the above lower limit value and the above upper limit value can be combined in any combination.

[0040] The polyethylene contained in the lubricating coating film composition of the present embodiment is not particularly limited. For example, it is 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 one or more selected from their groups. Additionally, 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 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. Additionally, the weight average molecular weight is determined, for example, by a GPC measurement method based on polystyrene conversion.

[0041] The lubricating coating film composition of the present embodiment contains 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. The total amount of the first polyethylene and the second polyethylene is 15% by mass or more and 40% by mass or less relative to the total amount of the above lubricating coating film composition. Additionally, the first polyethylene is UHMW-PE and the second polyethylene is HDPE.

[0042] Polyethylene has a tendency of having small intermolecular forces and a small coefficient of friction. Among them, HDPE has a tendency of having an even smaller coefficient of friction, and on the other hand, a small molecular weight and low wear resistance. In addition, UHMW-PE has a tendency of having a coefficient of friction larger than that of HDPE. On the other hand, it has a large molecular weight and high wear resistance. The lubricating coating film composition of the present embodiment contains HDPE and UHMW-PE. When the composition is fired above the melting points of the two polyethylenes to produce a lubricating coating film, in this lubricating coating film, the two polyethylenes melt and mix. During melting, 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 in a manner of winding around the periphery of UHMW-PE. Therefore, in the lubricating coating film formed by curing the above composition in a molten state, the region containing HDPE (hereinafter also referred to as the "HDPE region") has a tendency to cover the region containing UHMW-PE (hereinafter also referred to as the "UHMW-PE region"). As a result, HDPE with a smaller coefficient of friction is likely to appear on the surface of the lubricating coating film. Therefore, when a component slides on the surface of this lubricating coating film, the coefficient of friction becomes smaller. That is, the lubricating coating film of the present embodiment has excellent lubricity. Furthermore, in the above lubricating coating film provided on the base material, a UHMW-PE region with higher wear resistance exists inside the HDPE region (on the base material side). Therefore, even when a component slides repeatedly on the lubricating coating film, the HDPE region is not easily peeled off. In addition, even after the HDPE region peels off, the UHMW-PE region appears on the surface where the lubricating coating film and the component slide. Therefore, a decrease in the lubricity of the above lubricating coating film can be suppressed. That is, the lubricating coating film of the present embodiment has a tendency of having excellent lubricating durability. In addition, in the above lubricating coating film, the UHMW-PE regions are dispersed, and there is a tendency for HDPE regions to exist between these regions. In this way, the UHMW-PE regions are combined with each other via the HDPE regions, and a state in which the UHMW-PE regions and the HDPE regions are combined with each other in the lubricating coating film is formed. As a result, even when a component slides repeatedly on the lubricating coating film, the UHMW-PE regions and the HDPE regions are not easily peeled off, and there is a tendency to maintain the lubricity of the lubricating coating film. That is, the lubricating coating film of the present embodiment has a tendency of having excellent lubricity and lubricating durability.

[0043] In addition, by making the total amount of the first polyethylene and the second polyethylene 15% by mass or more and 40% by mass or less with respect to the total amount of the above lubricating coating film composition, there is a tendency for the lubricity and lubricating durability of the lubricating coating film to be further improved.

[0044] The composition for a lubricating coating film of the present embodiment preferably contains substantially no PFAS, and preferably contains no PFAS. The meaning of "substantially no PFAS" is not particularly limited. For example, it means that 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 relative to the total amount of the composition for a lubricating coating film. By making the composition for a lubricating coating film substantially contain no PFAS or contain no PFAS, there is a tendency for the lubricating durability to be improved and a tendency for the environmental friendliness to be improved. PFAS is not particularly limited as long as it is an organic compound in which part or all of the hydrogen atoms bonded to carbon in a hydrocarbon are substituted with fluorine (i.e., an organofluorine compound). Examples include polyfluoroalkyl compounds such as polytetrafluoroethylene (PTFE); perfluoroalkyl compounds such as perfluorooctane sulfonic acid and perfluorooctanoic acid.

[0045] Relative to the total amount of the composition for a lubricating coating film, the total amount of the first polyethylene and the second polyethylene is preferably 17.5 to 35.0% by mass, 20.0 to 30.0% by mass. By making the total amount of the first polyethylene and the second polyethylene within the above range, there is a tendency for the lubricity and lubricating durability of the lubricating coating film to be further improved.

[0046] The content of the first polyethylene relative to the total amount of the composition for a 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. By making the content of the first polyethylene within the above range, there is a tendency for the lubricity and lubricating durability of the lubricating coating film to be further improved.

[0047] The content of the second polyethylene relative to the total amount of the composition for a 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. By making the content of the second polyethylene within the above range, there is a tendency for the lubricity and lubricating durability of the lubricating coating film to be further improved.

[0048] In the composition for a 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, 1.5 to 2.5. By making this ratio within the above range, there is a tendency for the lubricity and lubricating durability of the lubricating coating film to be further improved.

[0049] 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, 1.5 million to 3 million. By making the weight-average molecular weight of the first polyethylene within the above range, there is a tendency for the lubricity and lubricating durability of the lubricating coating film to be further improved.

[0050] The density of the second polyethylene is preferably 0.94 to 1.10 g / cm3 、 0.95 to 1.00 g / cm 3 . By making the density of the second polyethylene within the above range, there is a tendency for the lubricity and lubrication durability of the lubricating coating film to be further improved.

[0051] The melting point of the first polyethylene is preferably 110 to 200 °C, 115 to 175 °C, 120 to 150 °C. By making the melting point of the first polyethylene within the above range, there is a tendency to be able to melt the lubricating coating film composition at an appropriate temperature to obtain a lubricating coating film.

[0052] The melting point of the second polyethylene is preferably 100 to 150 °C, 105 to 140 °C, 110 to 130 °C. By making the melting point of the second polyethylene within the above range, there is a tendency to be able to melt the lubricating coating film composition at an appropriate temperature to obtain a lubricating coating film.

[0053] The first polyethylene is preferably in the form of solid particles, and its median particle size (D50) is preferably 70 μm or less, 1 to 70 μm, 2 to 50 μm, 3 to 25 μm, 5 to 20 μm. By making the median particle size (D50) of the first polyethylene within the above range, there is a tendency for the lubricity of the lubricating coating film to be further improved.

[0054] The second polyethylene is preferably in the form of solid particles, and its median particle size (D50) is preferably 70 μm or less, 1 to 70 μm, 2 to 50 μm, 3 to 25 μm, 5 to 20 μm. By making the median particle size (D50) of the second polyethylene within the above range, there is a tendency for the lubricity of the lubricating coating film to be further improved.

[0055] In addition, the median particle size (D50) refers to the particle size corresponding to a cumulative degree of 50% in the particle size distribution measured by the laser diffraction and scattering method, and is the particle size measured in such a way that the number of particles with a particle size larger than the median particle size is the same as the number of particles with a particle size smaller than the median particle size.

[0056] The median particle size is not particularly limited, and for example, it can be measured using a laser diffraction type particle size distribution measuring device "MT3300EXII" manufactured by Microtrac.

[0057] 1.2. Wax

[0058] 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 for example, wax is cited. Wax is not particularly limited, and for example, 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 diamide are cited. Among them, the composition for a lubricating coating film preferably contains amide-modified polyethylene wax. In addition, amide-modified polyethylene wax means polyethylene wax in which hydrogen of polyethylene is substituted with an amide group.

[0059] The content of 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, 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. By making the composition for a lubricating coating film of the present embodiment contain wax, there is a tendency that the lubricity of the lubricating coating film is further improved.

[0060] The wax is preferably in the form of solid particles, and its median particle size is preferably 70 μm or less, 1 to 70 μm, 2 to 50 μm, 3 to 25 μm, 4 to 20 μm, 5 to 10 μm. By making the median particle size of the wax within the above range, there is a tendency that the lubricity of the lubricating coating film is further improved.

[0061] 1.3. Adhesive

[0062] The composition for a lubricating coating film of the present embodiment may contain an adhesive. As the adhesive, for example, one or more selected from the group consisting of engineering plastics such as epoxy resin, melamine resin, triazine resin, phenolic resin, polyamideimide (PAI), polyethersulfone (PES), and polyimide (PI) are cited. In addition, here, engineering plastics mean resins having a heat resistance temperature of 100 °C or higher, a tensile strength of 49 MPa or higher, and a flexural modulus of elasticity of 2.4 GPa or higher. The content of the adhesive 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, 50 to 60% by mass with respect to the total amount of the composition for a lubricating coating film. Alternatively, the content of the adhesive is, for example, 50 to 70% by mass with respect to the total amount of the composition for a lubricating coating film. By making the content of the adhesive within the above range, there is a tendency that the lubricity of the lubricating coating film is further improved.

[0063] When the composition for a lubricating coating film of the present embodiment contains an adhesive, as the adhesive, it preferably contains epoxy resin or phenolic resin as engineering plastics, and more preferably contains epoxy resin and phenolic resin as engineering plastics.

[0064] 1.4. Other additives

[0065] The composition for a lubricating coating film of the present embodiment may also contain other additives other than the above substances. There are no particular limitations on other additives, and examples include one or more selected from the group consisting of molybdenum disulfide, graphite, tungsten disulfide, boron nitride, calcium carbonate, talc, mica, melamine cyanurate (MCA), metal oxides, inorganic oxides, and oils (polyalphaolefins (PAO), silicone, polyalkylene glycols (PAG), esters, mineral oils). The content of the additive is not particularly limited, 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. In addition, by including molybdenum disulfide or the like, there is a tendency for the lubricity of the lubricating coating film to be further improved.

[0066] 2. Lubricating Coating Film

[0067] The lubricating coating film of the present embodiment is a coating film containing the composition for a lubricating coating film of the present embodiment described above. In addition, a lubricating coating film refers to a coating film for imparting lubricity to a base material on one side where the coating film is provided.

[0068] The lubricating coating film of the present embodiment is not particularly limited. For example, it contains the composition for a lubricating coating film of the present embodiment and is obtained by firing at a temperature higher than the melting point of all the polyethylene contained in the composition for a lubricating coating film.

[0069] The lubricating coating film of the present embodiment contains a plurality of polyethylenes. The content of polyethylene 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 with respect to the total mass of the lubricating coating film. The lower limit value of the content of polyethylene with respect to the total mass of the lubricating coating film may be any one 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 value of the content of polyethylene in the lubricating coating film with respect to the total mass may be any one of 100, 95, 90, 85, 80, 75, 70, 65, 60% by mass. In addition, the above lower limit value and the above upper limit value can be combined in any combination.

[0070] The polyethylene contained in the lubricating coating film of the present embodiment includes ultra-high molecular weight polyethylene (UHMW-PE, first polyethylene) and high density polyethylene (HDPE, second polyethylene). In addition, the polyethylene contained in the lubricating coating film is not particularly limited, and for example, it may contain 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.

[0071] The lubricating coating film of this embodiment preferably contains substantially no PFAS and preferably contains no PFAS. Substantially containing no PFAS is not particularly limited. For example, it means that 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 relative to the total amount of the lubricating coating film. By making the lubricating coating film substantially contain no PFAS or contain no PFAS, there is a tendency to improve lubricating durability and a tendency to improve environmental friendliness. PFAS is not particularly limited as long as it is an organic compound in which part or all of the hydrogen atoms bonded to carbon in a hydrocarbon are replaced by fluorine (i.e., an organofluorine compound). For example, polyfluoroalkyl compounds such as polytetrafluoroethylene (PTFE); perfluoroalkyl compounds such as perfluorooctane sulfonic acid and perfluorooctanoic acid, etc.

[0072] 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 relative to the total amount of the lubricating coating film. By making the total amount of the first polyethylene and the second polyethylene within the above range, there is a tendency to further improve the lubricity and lubricating durability of the lubricating coating film.

[0073] 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 relative to the total amount of the lubricating coating film. By making the content of the first polyethylene within the above range, there is a tendency to further improve the lubricity and lubricating durability of the lubricating coating film.

[0074] 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 relative to the total amount of the lubricating coating film. By making the content of the second polyethylene within the above range, there is a tendency to further improve the lubricity and lubricating durability of the lubricating coating film.

[0075] 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, 1.5 to 2.5. By making this ratio within the above range, there is a tendency to further improve the lubricity and lubricating durability of the lubricating coating film.

[0076] 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 for example, wax is mentioned. Wax is not particularly limited, and for example, one or more selected from the group consisting of amide-modified polyethylene wax, carboxyl-modified polyethylene wax, hydroxyl-modified polyethylene wax, polyolefin wax (paraffin wax), monoamide, and diamide are mentioned. Among them, the lubricating coating film preferably contains amide-modified polyethylene wax. 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, 5 to 10% by mass with respect to the total mass of the lubricating coating film. The lubricating coating film may not contain wax.

[0077] The lubricating coating film of the present embodiment may contain a binder. As the binder, for example, one or more selected from the group consisting of engineering plastics such as epoxy resin, melamine resin, triazine resin, phenolic resin, polyamideimide (PAI), polyethersulfone (PES), and polyimide (PI) are mentioned. 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, 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.

[0078] When the lubricating coating film of the present embodiment contains a binder, as the binder, it preferably contains an epoxy resin or a phenolic resin as an engineering plastic, and more preferably contains an epoxy resin and a phenolic resin as engineering plastics.

[0079] The lubricating coating film of the present embodiment may also contain other additives other than the above substances. Such other additives are not particularly limited, and for example, 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) are mentioned. The content of the additive is not particularly limited. 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 mass of the lubricating coating film. In addition, by containing molybdenum disulfide or the like, there is a tendency for the lubricity of the lubricating coating film to be further improved.

[0080] The lubricating coating film of the present embodiment may contain the above-mentioned various polyethylenes. In addition, the lubricating coating film of the present embodiment may also be a coating film containing the above-mentioned various polyethylenes and fired at a temperature higher than their melting points.

[0081] The lubricating coating film of the present embodiment may contain UHMW-PE, HDPE, and amide-modified polyethylene wax. In addition, the lubricating coating film of the present embodiment is not particularly limited. For example, it may be a coating film containing UHMW-PE, HDPE, and amide-modified polyethylene wax and fired at a temperature higher than the melting points of UHMW-PE, HDPE, and amide-modified polyethylene wax.

[0082] In the lubricating coating film of the present embodiment, polyethylene may exist in an island-like form on the surface of the coating film. In addition, in the lubricating coating film of the present embodiment, UHMW-PE and HDPE may exist in an island-like form on the surface of the coating film. The lubricating coating film of the present embodiment contains the composition for the lubricating coating film of the present embodiment, and the first polyethylene and the second polyethylene may exist in an island-like form on the surface of the lubricating coating film. This lubricating coating film tends to have more excellent lubricity. In addition, in this case, the regions where the first polyethylene and the second polyethylene exist, for example, are equivalent to the islands, and the other regions (for example, the regions where the binder exists) are equivalent to the sea.

[0083] 3. Manufacturing method of lubricating coating film

[0084] The manufacturing method of the lubricating coating film of the present embodiment includes a step of manufacturing a lubricating coating film using the composition for the lubricating coating film of the present embodiment. Among them, the step of manufacturing the lubricating coating film includes a firing step of firing the composition for the lubricating coating film at a temperature above the melting points of the first polyethylene and the second polyethylene. By firing the composition for the lubricating coating film at a temperature above the melting points of the first polyethylene and the second polyethylene, the first polyethylene and the second polyethylene are melted and mixed. Furthermore, the lubricating coating film obtained by cooling and solidifying after firing tends to have excellent lubricity and lubricating durability. In addition, on the surface of this lubricating coating film, the first polyethylene and the second polyethylene tend to exist in an island-like form. That is, it tends to have more excellent lubricity and lubricating durability.

[0085] The composition for the lubricating coating film and the lubricating coating film of the present embodiment tend to be able to provide a coating film with a low coefficient of friction even without PFAS. In addition, the composition for the lubricating coating film and the lubricating coating film of the present embodiment tend to have excellent lubricating durability (friction resistance) even without PFAS. In addition, the composition for the lubricating coating film and the lubricating coating film of the present embodiment tend to have excellent rust prevention, water repellency, and oil repellency in any one or more of them even without PFAS.

[0086] Figure 1 An example of a cross-sectional view showing the case of providing a lubricating coating film on a base material. In Figure 1In [description], a lubricating coating film 100 is provided on a base material 200. The lubricating coating film 100 includes a mixture 130 of polyethylene and wax, an additive 120, and an adhesive 110. The polyethylene and the wax may be only partially mixed, and in addition to that, they may exist independently or exist as a completely mixed mixture 130. In Figure 1 In [description], the first polyethylene and the second polyethylene exist in an island-in-sea structure on the surface of the lubricating coating film 100. Specifically, on the surface of the lubricating coating film 100, the regions where the mixture 130 exists are islands, and the regions where the adhesive 110 exists are the sea.

[0087] The lubricating coating film of the present embodiment includes the following modes.

[0088] 1. A lubricating coating film, which includes various polyethylenes (UHMW-PE, HDPE) and is obtained by firing at a temperature higher than their melting points.

[0089] 2. A lubricating coating film, which includes UHMW-PE, HDPE, and amide-modified polyethylene wax and is obtained by firing at a temperature higher than their melting points.

[0090] 3. A lubricating coating film, which has the composition described in Figure 2 [description].

[0091] 4. A lubricating coating film, in which the dissolved UHMW-PE and HDPE exist in an island-in-sea structure on the surface of the coating film.

[0092] 5. A lubricating coating film, which includes, as the 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 diamide.

[0093] 6. A lubricating coating film, which includes, as the 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).

[0094] 7. A lubricating coating film, which includes, as the adhesive, one or more selected from the group consisting of engineering plastics (epoxy resin, melamine resin, triazine resin, phenolic resin, PAI, PES, PI, etc.).

[0095] 4. Sliding device

[0096] The composition for a lubricating coating film of the present embodiment is applied to the surface of a base material to form a lubricating coating film. The base material is a structure on which a component slides, and the material of the base material is not particularly limited. For example, 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; metals such as aluminum, magnesium, iron, copper, tin, zinc, and lead and their alloys; and inorganic materials such as glass.

[0097] The material of the component is not particularly limited, and the same materials as those exemplified for the base material are cited.

[0098] The base material and the component may be of the same material or different materials from each other.

[0099] The sliding device having a base material and a component and the component sliding on the base material is not particularly limited. For example, a door lock mechanism, a window regulator, a seat track, a sunroof, a suspension, a brake, a seat belt mechanism, or a gear part of a steering system is cited.

[0100] Examples

[0101] Hereinafter, the present invention will be described in more detail using examples. The present invention is not limited by any of the following examples. In addition, unless otherwise specified, it is carried out at room temperature (25 °C) and 1 atmosphere.

[0102] In Figure 3 The compounds were mixed and stirred in the manner of the composition described, and the composition for a lubricating coating film of each experimental example was obtained. Then, after the composition for a lubricating coating film of each experimental example was applied to the base material, firing was carried out at 200 °C to obtain the lubricating coating film of each experimental example.

[0103] Figure 3 The abbreviations and components of the products described in Figure 3 The blank column indicates that the component is not used.

[0104] Binder: epoxy resin / phenolic resin (engineering plastic)

[0105] Additive: molybdenum disulfide powder

[0106] UHMW-PE: molecular weight: 1.8 million, melting point: 136 °C, median particle size: 10 μm

[0107] HDPE A: density: 0.94 or more, melting point: 125 °C

[0108] HDPE B: Density: 1.06, Melting point: 125 °C

[0109] HDPE C: Density: 0.98, Melting point: 125 °C

[0110] HDPE D: Density: 0.97, Melting point: 122 °C, Median particle size: 8 μm

[0111] PA12 A: Polyamide 12 powder, Melting point: 170 °C

[0112] PA12 B: Polyamide 12 powder, Melting point: 170 °C

[0113] PA12 C: Polyamide 12 powder, Melting point: 177 °C

[0114] PA12 D: Polyamide 12 powder, Melting point: 177 °C

[0115] Biopolymer A: Modified biopolymer, Melting point: 175 °C

[0116] Biopolymer B: Modified biopolymer, Melting point: 175 °C

[0117] Amide-modified polyethylene wax: Median particle size: 6 μm

[0118] In the Figure 3 table, μs represents the coefficient of static friction and μd represents the coefficient of kinetic friction. Additionally, the coefficient of static friction and the coefficient of kinetic friction are measured under the following conditions.

[0119] Equipment used: TRIBOGEAR Type 14 manufactured by Shinto Kagaku Co., Ltd.

[0120] Test piece: On a SUS301 test piece (thickness t = 0.3 mm), a lubricating coating film of each experimental example is formed with a thickness of 20 μm

[0121] Object material: SPCC-SB flat plate 25 × 25 mm

[0122] Speed: 0.4 mm / sec

[0123] Stroke width: 5 mm (The object material reciprocates on the lubricating coating film of each experimental example formed on the base material with this stroke width.)

[0124] Load: 24 N (Surface pressure: 0.0384 MPa)

[0125] Evaluation: Coefficient of static friction and coefficient of kinetic friction at the fifth sliding

[0126] μs is evaluated based on the following evaluation criteria. Evaluation A is the most excellent, and evaluations B, C, and D are inferior in this order. Lubricating coating films with a B evaluation or above can be applied to sliding devices.

[0127] A: μs ≤ 0.10

[0128] B: 0.10 < μs ≤ 0.15

[0129] C: 0.15 < μs ≤ 0.30

[0130] D: 0.30 < μs

[0131] μd is evaluated based on the following evaluation criteria. Evaluation A is the most excellent, and evaluations B, C, and D are inferior in this order. Lubricating coating films with a B evaluation or above can be applied to sliding devices.

[0132] A: μd ≤ 0.10

[0133] B: 0.10 < μd ≤ 0.15

[0134] C: 0.15 < μd ≤ 0.30

[0135] D: 0.30 < μd

[0136] For the lubricating coating films made from the lubricating coating film composition of Experimental Example 1 and the lubricating coating films made from the lubricating coating film compositions of Experimental Examples 12 to 15, the lubricating durability was evaluated. Specifically, in addition to performing 20,000 sliding operations, the wear depth (μm) of the test piece was measured under the same conditions as those for the measurement of the static friction coefficient and the dynamic friction coefficient.

[0137] The wear depth of the lubricating coating films made from the lubricating coating film compositions of Experimental Examples 12 to 15 is less than that of the lubricating coating films made from the lubricating coating film composition of Experimental Example 1. That is, it can be known that the lubricating coating films made from the lubricating coating film compositions of Experimental Examples 12 to 15 have excellent lubricating durability.

[0138] In addition, for the lubricating coating films made from the lubricating coating film compositions of Experimental Examples 12 to 15, the cross-section was observed with a scanning electron microscope (SEM), and it was confirmed that the first polyethylene and the second polyethylene exist in an island shape on the surface of the lubricating coating film.

[0139] Symbol Explanation

[0140] 100: Lubricating coating film

[0141] 110: Adhesive

[0142] 120: Additive

[0143] 130: Mixture of polyethylene and wax

[0144] 200: Base material

Claims

1. A lubricating coating composition comprising: The first polyethylene has a weight average molecular weight of 1,000,000 or more; and The second polyethylene has a density of 0.94 g / cm 3 above, The total amount of the first polyethylene and the second polyethylene is 15% by mass or more and 40% by mass or less relative to the total amount of the lubricating coating composition.

2. The lubricating coating composition according to claim 1, wherein The median particle size of the first polyethylene is less than 70 μm, The median particle size of the second polyethylene is 70 μm or less.

3. The lubricating coating composition according to claim 1, wherein 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.

4. The lubricating coating composition according to claim 3, wherein The median particle size of the amide-modified polyethylene wax is less than 70 μm.

5. The lubricating coating composition according to claim 1, wherein The lubricating coating composition contains 50% by mass or more and 70% by mass or less of an engineering plastic based on the total amount of the lubricating coating composition.

6. The lubricating coating composition according to claim 1, wherein Contains virtually no organic fluorine compounds.

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 exist in the form of islands on the surface of the lubricating coating.

8. A method for producing a lubricating coating, comprising the step of producing a lubricating coating using the lubricating coating composition according to any one of claims 1 to 6, The step of producing the lubricating coating includes a calcining step of calcining the lubricating coating composition at a temperature not lower than the melting point of the first polyethylene and the second polyethylene.

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