Coating composition for lubricating film and lubricating film formed by curing same

Abstract

Provided is a coating composition for a lubricating film whereby it is possible to form a lubricating film with excellent lubricating performance and water / corrosion resistance performance without the use of environmentally harmful PTFE. This coating composition for a lubricating film contains (A) a binder resin and (B) polyethylene particles. The polyethylene particles (B) are a composite of an inorganic or organic compound and polyethylene.

Description

Coating composition for lubricating film, and lubricating film formed by curing the same

[0001] The present invention relates to a coating composition for a lubricating film. Specifically, the present invention relates to a coating composition for a lubricating film capable of forming a lubricating film excellent in lubricity, water resistance, and corrosion resistance without using a fluorine-based compound that may cause environmental problems, and a lubricating film formed by curing the coating composition for a lubricating film.

[0002] For example, as described in JP-A-2017-514928, a coating composition for a lubricating film containing a binder containing a phenolic resin and an epoxy resin and a solid lubricant is known. As the solid lubricant, a fluororesin (PTFE), a polyethylene resin, a polyamide resin, etc. are disclosed, and the combined use of a fluororesin and a metal oxide or a metal nitride is also disclosed.

[0003] However, the above document has only examples using a fluororesin as the resin particles, and there is no description at all about the composite resin particles.

[0004] In recent years, fluorine-based compounds (PFAS) have been recognized as substances that may affect the environment, and it is required to reduce their usage as much as possible. The present inventors examined a coating composition for a lubricating film using various hydrocarbon-based polymer particles instead of PTFE particles, which are fluorine-based compounds, but the lubricity of the obtained film was insufficient, and the water resistance and corrosion resistance were inferior. When used in an environment where high temperature and high humidity or salt water exists, problems such as swelling, bulging, and / or peeling of the coating film due to water immersion, or corrosion of the painted metal occurred. However, no prior example was found that tried to solve the above problems while using hydrocarbon-based polymer particles.

[0005] JP-A-2017-514928

[0006] An object of the present invention is to provide a coating composition for a lubricating film that can form a lubricating film excellent in lubricating performance, water resistance, and corrosion resistance without using PTFE that affects the environment.

[0007] One embodiment of the present invention relates to a coating composition for lubricating films comprising (A) a binder resin and (B) polyethylene particles, wherein the polyethylene particles (B) are a composite of an inorganic or organic compound and polyethylene.

[0008] Furthermore, another embodiment of the present invention relates to a lubricating film obtained by curing the above-mentioned lubricating coating composition, and a sliding member equipped with the lubricating film.

[0009] The lubricating coating composition of the present invention can form a lubricating coating with high lubricity, water resistance, and corrosion resistance on the surface of various substrates.

[0010] [Component (A)] Component (A) of the present invention is a binder resin, which forms a lubricating film as a heat-resistant resin and functions as a binder that supports a solid lubricant described later. The resins that can be used are not particularly limited, but examples include phenolic resins, epoxy resins, polyamide-imide resins, polyimide resins, polyamide resins, polybenzimidazole, polyphenyl sulfide, silicone resins, polyacrylic resins, polyurethane resins, and polyolefin resins, and it is preferable that one or more resins selected from these be used. In particular, it is preferable that the component (A) contains a phenolic resin and an epoxy resin.

[0011] The phenolic resin may be a single type of phenolic resin or a mixture of two or more types of phenolic resins. Phenolic resins are resins obtained by condensing phenolic compounds such as phenol, cresol, and bisphenol A with aldehydes such as formaldehyde in the presence of an acidic or basic catalyst. Among these, those condensed with an acidic catalyst are called novolac-type phenolic resins, and those condensed with a basic catalyst are called resol-type phenolic resins.

[0012] The phenolic resin is not particularly limited, and either novolac-type phenolic resin or resol-type phenolic resin can be used. Resol-type phenolic resin is preferred. Resins into which methylol groups have been introduced are also included, and phenolic resins in which some or all of the introduced methylol groups have been alkyl etherified with an alcohol having 6 or fewer carbon atoms can also be used.

[0013] The binder resin may contain an epoxy resin separately from, or in addition to, the phenol resin. The epoxy resin may be a single type of epoxy resin or a mixture of two or more types of epoxy resins. The epoxy resin is preferably one with an epoxy equivalent weight of 600 to 4000.

[0014] The epoxy resin is not particularly limited, and one or more can be selected from among bisphenol-type epoxy resins, amine-type epoxy resins, phenol novolac-type epoxy resins, cresol novolac-type epoxy resins, resorcinol-type epoxy resins, phenol aralkyl-type epoxy resins, naphthol aralkyl-type epoxy resins, dicyclopentadiene-type epoxy resins, epoxy resins having a biphenyl skeleton, isocyanate-modified epoxy resins, tetraphenylethane-type epoxy resins, triphenylmethane-type epoxy resins, fluorene-type epoxy resins, etc.

[0015] Generally, bisphenol-type epoxy resins are those in which two phenolic hydroxyl groups of a bisphenol compound are glycidylated. Examples include bisphenol A type, bisphenol F type, bisphenol AD ​​type, bisphenol S type, or halogen, alkyl-substituted, hydrogenated, and dimer acid-modified versions of these bisphenols. In addition to monomers, high molecular weight compounds having multiple repeating units can also be suitably used.

[0016] When the binder resin in the composition of the present invention contains both a phenolic resin and an epoxy resin, the ratio of the two is 90:10 to 10:90 for phenolic resin to epoxy resin, preferably 80:20 to 20:80. The phenolic resin and epoxy resin become binder components upon thermal curing.

[0017] Polyamide-imide resins are not particularly limited as long as they are polymers having amide and imide bonds in their molecules, but for example, they can be prepared by polymerizing a diisocyanate compound and a trivalent carboxylic acid derivative having an acid anhydride group in a solvent containing urea bonds. Polyamide-imide resins may be used alone or in combination of two or more types.

[0018] The polyimide resin is not particularly limited as long as it is a polymer obtained by reacting raw materials containing tetracarboxylic dianhydride and diamine in its molecule. For example, a solution obtained by polymerizing polyamic acid, a precursor of the polyimide, in a solvent of a five-membered ring compound having a lactam structure containing nitrogen can be used. Tetracarboxylic dianhydride and diamine may be used individually or in combination of two or more. After coating the precursor, a film can be obtained by dehydration and ring closure by heating or chemical treatment with an acid or base.

[0019] Polyamide resins are synthetic resins having amide bonds, and are generally obtained by the condensation reaction of a polybasic acid having two or more carboxyl groups and a polyamine having two or more amino groups. Examples of polybasic acids include succinic acid, glutaric acid, adipic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, tetrahydrophthalic acid, endomethylenetetrahydrophthalic acid, and hexahydrophthalic acid. On the other hand, examples of polyamines include hydrazine, methylenediamine, ethylenediamine, trimethylenediamine, tetramethylenediamine, hexamethylenediamine, ethylaminoethylamine, methylaminopropylamine, iminobispropylamine, diethylenetriamine, triethylenetetramine, polyethyleneimine, diaminobenzene, triaminobenzene, diaminoethylbenzene, triaminoethylbenzene, diaminoethylbenzene, triaminoethylbenzene, polyaminonaphthalene, polyaminoethylnaphthalene, and their N-alkyl derivatives and N-acyl derivatives. Polyamide resins may be used individually or in combination of two or more types.

[0020] Polybenzimidazole can be obtained by reacting a tetraamine with an acid component such as a dicarboxylic acid, a corresponding dicarboxylic acid chloride, or a dicarboxylic acid active ester. Generally, a polybenzimidazole film can be obtained by coating a polyaminoamide, which is one of the polybenzimidazole precursors obtained by reacting a bisaminophenol compound with a dicarboxylic acid, and then dehydrating and cyclizing it by heating or chemical treatment with phosphoric anhydride, a base, or a carbodiimide compound.

[0021] Polyphenylene sulfide can be obtained by polymerizing p-dichlorobenzene and sodium sulfide in an amide solvent such as N-methylpyrrolidone or dimethylacetamide, or a sulfone solvent such as sulfolane, and adjusting the degree of polymerization by adding an alkali metal salt of a carboxylic acid or sulfonic acid.

[0022] The silicone resin can be any organopolysiloxane having siloxane units and functioning as a binder resin by curing or solvent removal (drying and solidification), and may also have functional organic modifying groups in the side chain or main chain, such as acrylic-modified silicone resins. Preferred silicone resins are (R3SiO 0.5 ) Siloxane unit, (R2SiO) Siloxane unit, (RSio 1.5 The branched organopolysiloxane contains one or more siloxane units independently selected from siloxane units or (SiO2)siloxane units (commonly referred to as M-siloxane units, D-siloxane units, T-siloxane units, and Q-siloxane units, respectively) (wherein R may be any organic group containing 1 to 30 carbon atoms, preferably an alkyl or aryl group having up to 8 carbon atoms, more preferably a methyl group, an ethyl group, or a phenyl group). In particular, silicone resins containing both D-siloxane units and T-siloxane units are preferred.

[0023] Polyacrylic resin may be a homopolymer or a copolymer, as long as it is obtained by polymerizing one or more acrylic monomers. Furthermore, there are no particular limitations on its structure or type. Examples of the acrylic monomers include alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and octyl (meth)acrylate (the number of carbon atoms in the alkyl group is preferably 1 to 8, more preferably 1 to 6, and particularly preferably 1 to 4); lower alkoxy lower alkyl (meth)acrylates such as methoxymethyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxymethyl (meth)acrylate, ethoxyethyl (meth)acrylate, and methoxybutyl (meth)acrylate; and 2-hydroxyethyl (meth)acrylate. Examples include hydroxy lower alkyl (meth)acrylates such as 3-hydroxypropyl (meth)acrylate; acrylamide, methacrylamide; (meth)acrylamides having an N-unsubstituted or substituted (especially lower alkoxy-substituted) methylol group, such as N-methylolacrylamide, N-methylolmethacrylamide, N-butoxymethylacrylamide, and N-butoxymethylmethacrylamide; phosphonyloxy lower alkyl (meth)acrylates such as phosphonyloxymethyl (meth)acrylate, phosphonyloxyethyl (meth)acrylate, and phosphonyloxypropyl (meth)acrylate; acrylonitrile; and one or more of acrylic acid, methacrylic acid, etc. Note that the above lower alkoxy and lower alkyl usually refer to alkoxy and alkyl having 1 to 5 carbon atoms, respectively, preferably 1 to 4 carbon atoms, more preferably 1 to 3 carbon atoms.

[0024] The polyurethane resin is not particularly limited, but a polyurethane resin obtained by reacting at least one polyol with at least one isocyanate is preferred.

[0025] The polyol resin is not particularly limited as long as it has two or more hydroxyl groups in one molecule, and conventionally known polyols can be used. Examples include polyester polyols, polycarbonate polyols, polyether polyols, polycaprolactone polyols, and polyalkylene polyols. The polyol resin may be used alone or in combination of two or more types.

[0026] [Component (B)] The composition of the present invention contains polyethylene particles as component (B). The polyethylene particles function as a solid lubricant in the composition. The polyethylene particles used in the present invention are characterized by being a composite of an inorganic or organic compound and polyethylene. Here, "composite" refers to a state in which an inorganic or organic compound is present on the surface of the polyethylene particles or inside the polyethylene particles, and is used as a concept that includes surface treatment of the polyethylene particles.

[0027] Examples of inorganic compounds include, but are not limited to, silicon compounds such as silica, aluminum compounds such as alumina, zirconium compounds such as zirconia, titanium compounds such as titania, zinc compounds, and tin compounds. Examples of organic compounds used include, but are not limited to, fatty acids such as stearic acid, alkylsilanes, polysiloxanes, acrylic silicon copolymers, alkyl titanates, metal soaps, perfluoroalkyl phosphate esters, lauroyl lysine, amines, and chitosan.

[0028] Furthermore, if the composite is a composite of an inorganic compound and polyethylene, it is preferable that the inorganic compound contains silicon, aluminum, or both. If silicon is included, examples of silicon compounds include silica, silicates, and silane coupling agents, and if aluminum is included, examples of aluminum compounds include alumina and aluminum hydroxide.

[0029] The content of the inorganic or organic compound in polyethylene particles, which are composites of an inorganic or organic compound and polyethylene, is preferably 1 to 30% by weight, more preferably 5 to 25% by weight, and even more preferably 10 to 20% by weight, based on the weight of the polyethylene particles (as a composite).

[0030] The polyethylene particles preferably have an average particle diameter (D50) of 0.1 to 30 μm, and more preferably a D50 of 0.1 to 10 μm. Here, the average particle diameter refers to the median particle diameter measured by laser diffraction scattering.

[0031] These composite particles of inorganic or organic compounds with polyethylene are commercially available. Examples of composite particles of inorganic compounds with polyethylene include Lanco 2510SF, Lanco 2520SF, and Lanco 2520EF, commercially available from Lubrizol. Examples of composite particles of organic compounds with polyethylene include Lanco 2530EF, Lanco 2540SF, Lanco 2540EF, and Lanco 2541SF, commercially available from Lubrizol.

[0032] The content of the composite polyethylene particles is 1 to 50 parts by weight, preferably 10 to 40 parts by weight, per 100 parts by weight of the binder resin.

[0033] [Other Components] In addition to components (A) and (B), the compositions of the present invention may appropriately contain various components depending on their application, as long as they do not impair the technical effects of the present invention. For example, they may include solid lubricants other than component (B), solvents (D), etc.

[0034] Examples of solid lubricants (C) other than component (B) include particles of organic compounds made of urethane resin, acrylic resin, polyamide resin, polypropylene resin, etc.; particles of inorganic compounds such as titanium nitride, titanium oxide, molybdenum disulfide, tungsten disulfide, graphite, aluminum oxide, silicon nitride, boron nitride, silicon dioxide, zinc oxide, tungsten carbide, etc.; silicone resin particles; metal particles such as lead; or mixtures thereof.

[0035] From the viewpoint of improving the wear resistance of the lubricating film under high load, the composition of the present invention may also contain, as a solid lubricant other than component (B), one or more metal oxides or metal nitrides selected from molybdenum disulfide, tungsten disulfide, graphite, titanium nitride, titanium oxide, aluminum oxide, silicon nitride, silicon dioxide, and mixtures thereof.

[0036] The content of solid lubricants other than these components (B) is 0 to 30 parts by weight, preferably 1 to 25 parts by weight, per 100 parts by weight of binder resin.

[0037] The composition of the present invention may contain a solvent (D) for purposes such as improving coatability. The solvent can be selected depending on the type of binder resin, but examples of solvents that can be used include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; esters such as methyl acetate and ethyl acetate; aromatic hydrocarbons such as toluene and xylene; organic halogen compounds such as methyl chloroform, trichloroethylene, and trichlorotrifluoroethane; N-methyl-2-pyrrolidone (NMP); N-ethyl-2-pyrrolidone (NEP); 1,3-dimethyl-2-imidazolidinone (DMI); γ-butyrolactone (GBL); 3-methoxy-N,N-dimethylpropanamide and methylisopyrrolidone (MIP); dimethylformamide (DMF) and dimethylacetamide (DMAC). These solvents may be one or a mixture of two or more. Methyl ethyl ketone is particularly preferred as the solvent. The content of these solvents is 5 to 1900 parts by weight, preferably 10 to 1000 parts by weight, per 100 parts by weight of binder resin.

[0038] The coating composition of the present invention may further contain, as necessary, one or more additives such as ultraviolet absorbers, light stabilizers, antioxidants, thermal polymerization inhibitors, leveling agents, defoamers, thickeners, settling inhibitors, pigments (organic coloring pigments, inorganic pigments), coloring dyes, infrared absorbers, fluorescent whitening agents, dispersants, conductive particles, antistatic agents, antifogging agents, and coupling agents, provided that the objectives of the present invention are not impaired. The content of these additives is 0.1 to 20 parts by weight, preferably 1 to 15 parts by weight, per 100 parts by weight of the binder resin.

[0039] The paint composition of the present invention may further contain an adhesion improving agent as needed. When the paint composition is applied to a substrate surface to form a lubricating film, the film may peel off if the adhesion between the lubricating film and the substrate surface is poor. In such cases, the adhesion between the lubricating film and the substrate surface can be improved by including an adhesion improving agent. Graphite can be used as the adhesion improving agent, and the amount used is 0 to 30 parts by weight, preferably 1 to 25 parts by weight, per 100 parts by weight of the binder resin.

[0040] The composition of the present invention can be suitably used as a coating composition for lubricating films, and can form a lubricating film with excellent lubricity, water resistance, and corrosion resistance on the surface of any substrate.

[0041] The material of the substrate is not particularly limited, but examples include metals such as iron, aluminum, and copper, rubber, resin, and combinations thereof. The substrate preferably contains metal, and more preferably is made of metal. The surface of the substrate may be subjected to roughening treatments such as electrolytic etching, chemical etching, shot blasting, or chemical treatments such as phosphates, as needed, in order to improve adhesion.

[0042] In the present invention, the lubricating coating composition described above can be applied to the surface of a substrate, and the composition can be cured by heating, thereby forming a coating on the surface of the substrate.

[0043] The method for applying the coating composition for the lubricating film to the surface of the substrate is not particularly limited. For example, conventionally known coating methods such as roll coating, coil coating, screen printing, spray method, tumbling method, immersion method, brush coating method, etc. can be used. After application, it is preferable to leave it for a certain period of time for leveling. By leveling, the lubricity of the obtained film can be improved. Although the substrate may be preheated during application, it is preferable to apply it at room temperature (about 25°C) in terms of workability. Then, when the coating composition for the lubricating film contains a solvent, for example, it is preferable to leave it at room temperature for 1 to 60 minutes, or heat it at 40 to 80°C for 1 minute to 60 minutes to remove the solvent. And after removing the solvent, the composition film applied to the surface of the substrate can be heated to obtain a cured film. The heating mode can be adjusted as appropriate. For example, it can be carried out at 170 to 200°C for 5 to 90 minutes. If necessary, the removal of the above solvent and the heating for resin curing may be carried out simultaneously. The present invention also relates to the lubricating film obtained in this way. The thickness of the film of the present invention is arbitrary, but for example, it can be 1 to 50 μm, preferably 5 to 40 μm, and more preferably 10 to 30 μm.

[0044] The lubricating film of the present invention has high water resistance and corrosion resistance. The water resistance and corrosion resistance can be evaluated, for example, by a salt spray test (JIS Z2371).

[0045] The lubricating coating of the present invention can be suitably used on the surface of sliding members. The type of sliding member is not particularly limited, but examples include those made of metal, plastic, or rubber. Examples of metal sliding members include compressor shafts, compressor bearings, compressor swash plates, compressor pistons, crankshafts, slide bearings, differential gears, differential gear washers, oil pump gears, pistons, piston rings, piston pins, gaskets, door locks, guide rails, seat belt buckles, brake pads, brake pad clips, brake shims, brake insulators, hinges, and screws. Examples of plastic sliding members include door panels, instrument panels, door locks, bearings, gears, belt tensioners, fixing belts, and pressure belts. Examples of rubber sliding components include timing belts, conveyor belts, sunroof body seals, glass runs, weatherstrips, oil seals, gaskets, wiper blades, doctor blades, charging rollers, developing rollers, toner supply rollers, transfer rollers, heat rollers, pressure rollers, cleaning blades, paper feed rollers, transport rollers, doctor blades, intermediate transfer belts, intermediate transfer drums, heat belts, and other drive components, sliding components, and transport parts for automobiles, copiers, printers, etc.

[0046] The sliding member of the present invention includes a base material having a lubricating film formed on its surface. For example, it can be manufactured through a process of applying the paint composition for the lubricating film to the surface of the base material and a process of heating the paint composition for the lubricating film to form a lubricating film on the surface of the base material. The base material preferably contains a metal and is more preferably made of metal. The manufacturing method of the sliding member of the present invention can further include a process of press-working or punching the base material having the lubricating film formed on its surface. In particular, when the base material is made of metal, it is possible to manufacture a sliding member by press-working, punching, etc. the base material after forming a lubricating film on the surface of the base material, and the sliding member can be efficiently manufactured. Examples of such sliding members include, for example, a crankshaft, a compressor shaft, a slide bearing, a gear, an oil pump gear, a piston, a piston ring, a piston pin, a gasket, a door lock, a guide rail, a seat belt buckle, a brake pad, a brake pad clip, a brake shim, a brake insulator, a hinge, a screw, or a pressure pad. Brake pads, brake pad clips, brake shims, and brake insulators are preferred, brake pads and brake pad clips are more preferred, and brake pad clips are even more preferred.

[0047] Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to the examples.

[0048] <Raw Materials> Phenolic resin: Resol-type phenolic resin (softening point 80-100°C) Epoxy resin: Bisphenol A type epoxy resin (epoxy equivalent 780-850) Polyethylene particles 1: Polyethylene particles composited with an inorganic compound having a median particle size of 4.8 μm as determined by laser diffraction scattering particle size distribution measurement (density 1.05) Polyethylene particles 2: Polyethylene particles composited with an inorganic compound having a median particle size of 4.3 μm as determined by laser diffraction scattering particle size distribution measurement (density 1.07) Polyethylene particles 3: Polyethylene particles composited with an organic compound having a median particle size of 3.8 μm as determined by laser diffraction scattering particle size distribution measurement (density 0.92) Polyethylene particles 4: Polyethylene particles having a median particle size of 3.9 μm as determined by laser diffraction scattering particle size distribution measurement (density 0.97) Urethane particles: Urethane particles surface-treated with an inorganic compound having a median particle size of 8.4 μm as determined by laser diffraction scattering particle size distribution measurement (density 1.18) Alumina particles: Alumina particles with a median particle size of 0.085 μm as measured by laser diffraction scattering particle size distribution (density 4.2) Polytetrafluoroethylene particles: Polytetrafluoroethylene particles with a median particle size of 0.24 μm as measured by laser diffraction scattering particle size distribution (density 2.0) Graphite particles: Graphite particles with a median particle size of 2.7 μm as measured by laser diffraction scattering particle size distribution (density 2.3) Carbon black: Black carbon black particles with a primary particle size of 0.099 μm as measured by laser diffraction scattering particle size distribution (density 2.0)

[0049] [Examples 1-3 and Comparative Examples 1-3] Various raw materials were mixed in the proportions shown in Table 1 to obtain the lubricating coating compositions of Examples 1-3, Comparative Examples 1-5, and Reference Examples 1-2. The values ​​shown in Table 1 represent parts by weight.

[0050]

[0051] [Lubricating film formation] The obtained paint composition was spray-coated onto a solvent-degreased test piece, dried at 80°C for 10 minutes, and then baked at 200°C for 20 minutes to obtain an evaluation test piece.

[0052] [Coefficient of Friction] Using a reciprocating friction and wear testing machine that moves a 1 / 2-inch steel ball with a vertical load applied to a stainless steel plate (SUS301) with a lubricating film formed on it back and forth, the coefficient of dynamic friction (unit: none) during sliding after 10,000 cycles of sliding against the steel ball was measured under the conditions of a sliding speed of 120 cpm, a load of 1 kg, and a sliding distance (stroke) of 4 mm.

[0053] [Durability] Using the above-mentioned reciprocating friction wear testing machine, sliding tests were conducted under the same conditions, and the number of cycles until the coefficient of friction increased significantly was measured. The results were judged according to the following criteria: ◎: 30,000 cycles or more, ○: 10,000 to 29,999 cycles, ×: less than 10,000 cycles

[0054] [Salt Spray Test] Using steel plates (SPCC-SB) with a lubricating coating, the condition of blistering and rust on the coating surface was evaluated by visual observation according to the following criteria after exposure for 300 hours in accordance with the salt spray test method (JIS Z2371). ○: No blistering or rust observed, ×: Blistering or rust observed.

[0055] The lubricating coating compositions containing surface-treated polyethylene particles in Examples 1 to 3 can form a lubricating film with excellent lubricity, water resistance, and corrosion resistance, and exhibit higher durability than the reference example lubricating coating composition containing polytetrafluoroethylene particles. Furthermore, even when the binder ratio is changed within a specified range (Example 4), good lubricity and water / corrosion resistance are achieved. On the other hand, the lubricating film formed from the lubricating coating composition containing polyethylene particles in Comparative Example 1 showed inferior lubricity and water / corrosion resistance. The lubricating coating compositions of Comparative Examples 2 to 4 showed insufficient lubricity and water / corrosion resistance. This indicates that polyethylene particles surface-treated with inorganic or organic compounds are essential for the functional expression of the present invention.

[0056] To improve adhesion, various raw materials were mixed in the proportions shown in Table 2 to obtain the lubricating coating compositions of Examples 5 and 6. The values ​​shown in Table 2 represent parts by weight.

[0057]

[0058] [Mandrel Bending Test] Using a steel plate (SPCC-SB) with a lubricating coating, a bending test was performed using a 2Φ mandrel in accordance with the mandrel bending test method (JIS K5600). After that, a peel test was performed using commercially available cellophane tape, and the adhesion of the coating was evaluated by visual observation according to the following criteria: ○: No peeling, △: More than half peeling, ×: More than half peeling

[0059] As seen in Examples 5 and 6, adhesion can be further improved by combining it with an adhesion improving agent.

[0060] The present invention can be used in various products equipped with a lubricating coating, and is particularly suitable for use in the manufacture of sliding members equipped with a lubricating coating.

Claims

1. A coating composition for a lubricating film comprising (A) a binder resin and (B) polyethylene particles, wherein the polyethylene particles are a composite of an inorganic or organic compound and polyethylene.

2. The coating composition for lubricating films according to claim 1, wherein the particle size (D50) of the polyethylene particles is 0.1 to 10 μm.

3. The coating composition for lubricating films according to claim 1, wherein the content of polyethylene particles is 1 to 50 parts by weight per 100 parts by weight of the binder resin.

4. The coating composition for lubricating films according to claim 1, wherein the polyethylene particles are a composite of an inorganic compound and polyethylene.

5. The lubricating coating composition according to claim 4, wherein the inorganic compound comprises silicon, aluminum, or both.

6. The coating composition for lubricating films according to claim 4, wherein the content of the inorganic compound is 1 to 30% by weight of the polyethylene particles.

7. The coating composition for lubricating films according to claim 1, characterized in that the binder resin is one or more selected from phenolic resin, epoxy resin, polyamide-imide resin, polyimide resin, polyamide resin, polybenzimidazole, polyphenyl sulfide, silicone resin, polyacrylic resin, polyurethane resin, and polyolefin resin.

8. The lubricating coating composition according to claim 1, wherein the binder resin contains one or more selected from novolac-type phenolic resin, resol-type phenolic resin, and epoxy resin.

9. The coating composition for lubricating films according to claim 1, further comprising organic compound particles, inorganic compound particles, silicone resin particles, metal particles, or a mixture thereof as a solid lubricant.

10. The coating composition for lubricating films according to claim 1, further comprising an adhesion improving agent.

11. A lubricating film obtained by curing a coating composition for lubricating films according to any one of claims 1 to 10.

12. The lubricating film according to claim 11, wherein the film thickness is 10 to 30 μm.

13. A sliding member comprising the lubricating coating described in claim 11.

14. A sliding member according to claim 13, selected from a compressor shaft, compressor bearing, compressor swash plate, compressor piston, crankshaft, slide bearing, differential gear, differential gear washer, oil pump gear, piston, piston ring, piston pin, gasket, door lock, guide rail, seat belt buckle, brake pad, brake pad clip, brake shim, brake insulator, hinge, screw, door panel, instrument panel, bearing, gear, belt tensioner, fixing belt, pressure belt, timing belt, conveyor belt, sunroof body seal, glass run, weatherstrip, oil seal, packing, wiper blade, doctor blade, charging roller, developing roller, toner supply roller, transfer roller, heat roller, pressure roller, cleaning blade, paper feed roller, transport roller, doctor blade, intermediate transfer belt, intermediate transfer drum, heat belt, drive member for automobiles, for copiers, for printers, sliding member, and transport unit.

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