JP2006077073A - Sliding member and resin coating composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sliding member resistant to the abrasion of the member by a coating film formed on the sliding part of the sliding member and provide a resin coating composition for forming the coating film. <P>SOLUTION: The sliding member has a surface coating film formed at least on the sliding part of the surface of a substrate. The coating film is a porous resin coating film having an interconnected pore ratio of ≥10% and produced by forming a coating layer containing a resin, a pore-forming material and hard particles, extracting the pore-forming material from the coating layer by using an extraction solvent dissolving the pore-forming material and unable to dissolve the resin and the hard particle and impregnating a lubricating oil into the interconnected pores formed by the extraction process. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a sliding member on which a film capable of preventing wear of a substrate is formed and a resin coating composition capable of forming the film.

Conventionally, various members are known as sliding members that come into contact with a mating member while friction. As an example, the surface of the base material has a coating layer in which a solid lubricant imparting a lubricating function, hard particles of a reinforcing agent, and a resin binder that fixes the solid lubricant and the hard particles to the base material are blended. There is a method of forming and improving the wear resistance and friction coefficient of the sliding member by the coating layer.
By blending a polyamideimide (hereinafter abbreviated as PAI) resin with a solid lubricant such as epoxy resin, hard particles such as alumina, and polytetrafluoroethylene (hereinafter abbreviated as PTFE) resin, a piston skirt, etc. A surface coating layer exhibiting high wear resistance even under severe use conditions is known (Patent Document 1).
In addition, a surface coating layer exhibiting high wear resistance even under severe use conditions such as a piston skirt by blending microcapsules impregnated with PAI resin is known (Patent Document 2).
Further, a surface coating layer exhibiting high wear resistance is known by impregnating and firing PTFE resin and expanded graphite into a sintered metal and post-impregnating a lubricating oil such as silicone oil into an oil-impregnated resin coating material. (Patent Document 3).

However, since the surface coating described in Patent Document 1 is a solid lubrication system, the adhesion and wear resistance on the sliding surface are insufficient, so it is necessary to reduce the friction coefficient and improve the wear resistance.
In addition, since the surface coating described in Patent Document 2 is fired after a coating liquid containing microcapsules is applied, the firing temperature is such that the outer wall of the microcapsules and the oil contained in the microcapsules can withstand. Not applicable. Therefore, there is a drawback that heat-resistant resins such as polyimide (hereinafter abbreviated as PI) resin and PTFE resin cannot be used. In addition, the microcapsules are expensive and have a problem in use in terms of cost.
Further, the surface coating described in Patent Document 3 uses expanded graphite to form pores and is post-impregnated with a lubricating oil. However, since expanded graphite has low wear resistance, the wear resistance of the coating is accordingly increased. There is a problem that it is only reduced and lowered.
JP 2004-149622 A JP 2002-066943 A JP 2003-214431 A

  The present invention has been made in order to cope with such problems, sufficiently supplying lubricating oil to the sliding surface, forming a good oil film, and suppressing the wear amount of the coating layer to a sufficiently low level. An object of the present invention is to provide a sliding member having a surface coating that can be formed and a resin coating composition that can form the coating.

The sliding member of the present invention is a sliding member in which a surface coating is formed on at least a sliding portion of the surface of a substrate, and the surface coating is a porous resin coating having a communication porosity of 10% or more. It is characterized by being.
The porous resin coating is a coating layer containing a resin, a pore-forming material, and hard particles, and then is coated with an extraction solvent that dissolves the pore-forming material and does not dissolve the resin and hard particles. It has the communicating hole obtained by extracting the said pore formation material from a layer, It is characterized by the above-mentioned.
The communication hole is impregnated with lubricating oil.
The resin coating composition of the present invention is a resin coating composition for forming a porous resin film comprising a resin, a pore-forming material, and hard particles, wherein the pore-forming material is a coating material. It is a substance that is extracted by an extraction solvent that dissolves the pore-forming material and does not dissolve the resin and hard particles after film formation.

In the sliding member according to the present invention, a porous resin film having a communication pore ratio of 10% or more is formed on the surface, and the porous resin film is impregnated with the lubricating oil through the communication holes and is applied to the sliding surface. Therefore, the lubricity of the sliding member surface can be maintained for a long period of time. Moreover, a good oil film can be formed on the sliding surface of the sliding member only by changing the coating layer of the sliding member without changing the shape of the sliding member, and the life of the sliding member can be extended.
Lubricating oil is not kneaded into the sliding member, but is impregnated in the communication hole, so that the fluidity of the lubricating oil to the sliding surface is secured through the communication hole. When the lubricating oil is consumed on the surface, the impregnated lubricating oil is always supplied to the sliding surface through the communication hole, so that 60% or more of the total impregnated lubricating oil can be used as the lubricating oil.
Note that the fact that it can be used as a lubricating oil means that the lubricating oil can ooze onto the surface of the porous resin and can impart lubricity to the sliding surface in each application and use condition.
Since the resin coating composition according to the present invention is formed by blending a component that forms a porous resin film having a communication porosity of 10% or more, the above-mentioned sliding member surface film is formed on the surface of the sliding member. Is possible.

The sliding member of the present invention has a surface coating made of a porous resin having a communication porosity of 10% or more. This surface coating can be impregnated with a lubricating oil.
Hereinafter, the resin, the pore forming material, and the hard particles constituting the resin coating composition of the present invention will be described following the communication porosity, and then the resin solvent, the extraction solvent, the porous resin film forming method, and the sliding member surface film Will be described.

When considering the porosity of the porous material having pores inside, the porous material is an aggregate of a plurality of spheres in which one sphere is gathered, and a space existing in the gap between the individual spheres. Considering that it consists of pores, face-centered cubic lattice and hexagonal close-packed packing are the most densely packed spheres by point contact, and their filling rate is (volume of sphere ÷ volume of circumscribed cube) ÷ (positive Calculated by the height of the triangle divided by the base) divided by the height of the regular tetrahedron divided by one side, both are 74%. The communication porosity defined as (100-filling rate) is 26%.
The above calculation is a case where spheres of the same size are considered. However, when spheres of a plurality of sizes are filled, the filling rate becomes larger than the hexagonal close-packed filling, and the communication porosity becomes smaller.
Further, when the powdered spherical resin particles are sintered after compression molding, there is no point contact, and the spherical resin particles are deformed and brought into surface contact. For this reason, a filling rate becomes larger than hexagonal close-packed filling, and a communicating porosity becomes smaller. For this reason, the limit of the communication porosity of the conventional sintered resin molding is about 20%. Moreover, when it is set as a film, since a resin component may enter the inside of a pore formation material, a communicating porosity becomes still smaller.

上記、数１において、各符号の意味を以下に示す。
Ｖ；焼成された洗浄前成形体の体積
ρ；焼成された洗浄前成形体の密度
Ｗ；焼成された洗浄前成形体の重量
Ｖ1；樹脂粉末の体積
ρ1；樹脂粉末の密度
Ｗ1；樹脂粉末の重量
Ｖ2；気孔形成材の体積
ρ2；気孔形成材の密度
Ｗ2；気孔形成材の重量
Ｖ3；洗浄後の多孔質樹脂の体積
Ｗ3；洗浄後の多孔質樹脂の重量
Ｖ'2；洗浄後に多孔質樹脂に残存する気孔形成材の体積 The communication pore ratio in the present invention refers to the ratio of the total volume of pores that are continuous with each other in the resin molded body to the volume of the resin molded body.
Specifically, the communication porosity was calculated by the method shown in Equation (1) in Equation 1.

In the above Equation 1, the meaning of each symbol is shown below.
V; volume ρ of the fired pre-cleaned molded body; density W of the fired pre-cleaned molded body; weight of the fired pre-cleaned molded body V1; volume of resin powder ρ1; density of resin powder W1; Weight V2: Pore-forming material volume ρ2; Pore-forming material density
W2: Weight of pore forming material V3; Volume of porous resin after washing W3; Weight of porous resin after washing V′2; Volume of pore forming material remaining in porous resin after washing

  In the present invention, a porous resin film having a communicating porosity of 10% or more, preferably 20% or more, more preferably 30% to 70% is obtained by the production method described below. If it is less than 10%, the characteristic excellent sliding characteristics by oil lubrication cannot be shown. The porous resin coating used for the sliding member surface coating of the present invention has a film thickness of several tens of μm to several hundreds of μm, and the same thickness as the size of the pores. It can be communicated from the surface. In order to exhibit excellent sliding characteristics under conditions where the lubricant is dilute, it is preferable to have a communication porosity of 30% or more.

As the resin that can be used in the resin coating composition of the present invention, any resin that is excellent in heat resistance and lubricity that does not thermally deteriorate when the sliding member is used at a high temperature can be used. Specific examples include PI resin, PTFE resin, epoxy resin, phenol resin, and silicone resin.
Among these, a resin coating composition in which hard particles and a pore-forming material described later are blended with a resin mixture composed of a PI-based resin and a PTFE resin, in particular, forms a sliding member surface film having excellent frictional wear resistance. Is preferred.

The PI-based resin that can be used in the present invention is a resin having at least an imide bond in the molecule, and the PTFE resin and the hard particles are used without being thermally deteriorated when the sliding member is used at a high temperature. Any resin that binds and has excellent adhesion to the surface of the sliding member can be used. For example, PI resin, PAI resin, polyester imide resin, polyester amide imide resin, etc. can be mentioned. Of these PI resins, PI resins and PAI resins are preferred. Moreover, an aromatic PI resin or an aromatic PAI resin in which an imide bond or an amide bond is bonded via an aromatic group is particularly preferable. When it is an aromatic resin, the binding property between the PTFE resin and the hard particles is excellent, and the heat resistance of the obtained coating layer is excellent. PI resin is a PI resin precursor obtained by ring-opening polyaddition reaction of acid dianhydride and diamine in an aprotic polar solvent such as N-methyl-2-pyrrolidone (NMP) or dimethylacetamide (DMAC). It can be obtained by heat-dehydrating and ring-closing polyamide carboxylic acid. The resin component in the wear-resistant and non-adhesive coating agent is used even in the state of polyamide carboxylic acid, in the state of PI resin, or even in the state where these are mixed. be able to.
A PAI resin is a resin having an imide bond and an amide bond in the molecule. The imide bond of the aromatic PAI resin may be a precursor such as polyamic acid, a closed imide ring, or a state in which they are mixed. Such aromatic PAI resins include PAI resins produced from aromatic primary diamines such as diphenylmethanediamine and aromatic tribasic acid anhydrides such as mono- or diacyl halide derivatives of trimellitic anhydride, aromatic There are PAI resins produced from tribasic acid anhydrides and aromatic diisocyanate compounds such as diphenylmethane diisocyanate. Furthermore, as PAI resins having a larger ratio of imide bonds than amide bonds, aromatic, aliphatic or aliphatic There are PAI resins produced from cyclic diisocyanate compounds and aromatic tetrabasic acid dianhydrides and aromatic tribasic acid anhydrides, and any PAI resin can be used.
Moreover, PI resin and PAI resin can also be used together.

  The PI resin and PAI resin that can be used in the present invention are preferably resin solutions in which a PTFE resin, a pore-forming material, and hard particles, which will be described later, can be easily blended. Moreover, PAI resin can also be used as a powder.

The PTFE resin that can be used in the present invention is composed of repeating units of —CF ₂ CF ₂ —, has a melting point of 327 ° C., and has a melt viscosity of about 10 ¹⁰ to 10 ¹¹ Pa · s at about 340 to 380 ° C. It is suitable for a sliding member that is exposed to a high-temperature atmosphere like a piston of an internal combustion engine because of its excellent heat resistance. As commercial products of PTFE resin, Fullon L169, 170, 171 (above, trade name manufactured by UK IC Corporation), Polyflon M15, Lubron L-2, L-5, LD-1 (above) , Daikin Industries, Ltd. product name), Teflon 7J, TLP-10, TLP-10F-1 (above, DuPont product name), Fullon G163 (Asahi Glass Co., Ltd. product name), and the like. In addition, the recycled PTFE resin obtained by pulverizing the PTFE resin fired once more than the unmolded PTFE resin is used, or the γ-ray irradiation treatment is performed on the unmolded PTFE resin instead of or together with the recycled PTFE resin. PTFE resin powder having a reduced molecular weight can be used. An example of a commercially available PTFE resin for lubricant that has been subjected to γ-ray irradiation treatment is a trade name, KT400H, manufactured by Kitamura Co., Ltd.

  The form of the PTFE resin may be a molding powder, or may be a so-called solid lubricant fine powder. The average particle size is in the range of 0.1 to 20 μm, preferably 0.2 to 10 μm. When the average particle size is within this range, aggregation or the like does not occur in the resin coating composition, and the smoothness of the coating film and coating layer after coating, drying and baking is maintained.

  The blending ratio of the PTFE resin that can be used in the present invention is 1% by volume to 60% by volume, preferably 5% by volume to 30% by volume, based on the solid content of the resin coating composition. If it is less than 1% by volume, there is no effect, and if it exceeds 60% by volume, the desired mechanical strength cannot be obtained.

The pore-forming material that can be used in the present invention has a melting point higher than the firing temperature of the resin, and is blended with the resin and hard particles to form a coating layer, and then the pores are formed without dissolving the resin and hard particles. Any substance that can be dissolved and extracted from the coating layer using an extraction solvent that dissolves the material can be used.
The pore-forming material is preferably an inorganic salt compound, an organic salt compound, or a mixture thereof, and particularly preferably a water-soluble substance that facilitates the washing and extraction process. Further, an alkaline substance, preferably a weak alkaline substance that can be used as a rust preventive is preferred. Examples of the weak alkali salt include organic alkali metal salts, organic alkaline earth metal salts, inorganic alkali metal salts, inorganic alkaline earth metal salts, and the like. It is preferable to use an organic alkali metal salt or an organic alkaline earth metal salt because even when the unextracted component falls off, it is relatively soft and hardly damages the rolling surface and the sliding surface. In addition, you may use these metal salts 1 type or in mixture of 2 or more types. In addition, it is preferable to use a water-soluble weak alkali salt because inexpensive water can be used as the extraction solvent, and waste liquid treatment at the time of pore formation becomes easy.
Further, in order to prevent melting of the pore forming material during firing, the pore forming material uses a substance having a melting point higher than the firing temperature of the resin used.
Water-soluble organic alkali metal salts that can be suitably used in the present invention include sodium benzoate (melting point 430 ° C.), sodium acetate (melting point 320 ° C.) or sodium sebacate (melting point 340 ° C.), sodium succinate, stearic acid Sodium etc. are mentioned. Sodium benzoate, sodium acetate, or sodium sebacate is particularly preferred because of its high melting point, compatibility with various resins, and high water solubility.
Examples of the inorganic alkali metal salt include potassium carbonate, sodium molybdate, potassium molybdate, and sodium tungstate.

The average particle diameter of the pore-forming material that can be used in the present invention is preferably controlled to 1 to 500 μm. More preferably, it is 1-200 micrometers, More preferably, it is the range of 1-40 micrometers.
The mixing ratio of the pore-forming material that can be used in the present invention is 10% by volume or more, preferably 20% by volume or more, more preferably 30% by volume to 70% with respect to the total amount including the resin powder, the pore-forming material, and the hard particles. Volume%.
After extraction of the pore-forming material with the extraction solvent, the amount of pore-forming material remaining in the coating layer is very small. Therefore, assuming that the volume of the pore-forming material is approximately the volume of the communicating hole, the mixing ratio of the pore-forming material is 10 volumes. If it is less than%, the excellent sliding characteristics characteristic of oil lubrication cannot be exhibited. Further, in order to exhibit excellent sliding characteristics under conditions where the lubricant is dilute, it is preferable to blend 30% by volume to 70% by volume of a pore forming material.

  The hard particles that can be used in the present invention are blended for the purpose of improving the interposition of the lubricating oil by improving the elastic modulus of the porous resin that becomes the surface coating of the sliding member and reducing the contact area. Moreover, it mix | blends in order to improve the abrasion resistance of a porous resin film.

  The addition amount of the hard particles that can be used in the present invention is preferably 1 to 60% by volume, desirably 3 to 30% by volume, based on the total amount including the resin and pore forming material. If it is less than 1% by volume, there is no effect, and if it exceeds 60% by volume, the paintability is poor.

  As the shape of the hard particles that can be used in the present invention, a spherical particle produced by a combustion method or the like is most desirable because it has a low aggressiveness to the counterpart material and a small viscosity increase of the paint. The lump produced by vapor phase growth is the next best. Next, crushed powder produced by a crushing method is preferred.

  Examples of the resin solvent that can be used in the present invention include ketones such as acetone and methyl ethyl ketone, esters such as methyl acetate and ethyl acetate, aromatic hydrocarbons such as toluene and xylene, N-methyl-2-pyrrolidone (NMP), Aprotic polar resin solvents such as methyl isopyrrolidone (MIP), dimethylformamide (DMF), dimethylacetamide (DMAC), and the like can be used. These resin solvents preferably contain an aprotic polar component as an essential component. Moreover, an aprotic polar solvent and another resin solvent can be used together.

  The extraction solvent that can be used in the present invention is an extraction solvent that dissolves the pore-forming material and does not dissolve the resin and hard particles. For example, water and alcohol-based, ester-based, and ketone-based solvents that are compatible with water. Etc. can be used. Among these, it is appropriately selected according to the above conditions depending on the type of resin and pore forming material. These extraction solvents may be used alone or in combination of two or more. It is preferable to use water because of its advantages such as easy waste liquid treatment and low cost.

Examples of the method for obtaining the resin coating composition of the present invention include the following methods.
(1) A method in which a pore-forming material and hard particles are blended in a resin varnish obtained by dissolving a PI resin in a resin solvent and stirred uniformly.
(2) PTFE resin powder, pore-forming material and hard particles are blended in an extraction solvent, and the pore-forming material is dissolved by stirring and dispersed, and then the extraction solvent is removed to form pores. A material blend is obtained. Next, this pore-forming material composition is blended in a resin varnish and stirred uniformly.
(3) After mixing the PI resin powder, pore forming material and hard particles in the extraction solvent, stirring to dissolve the pore forming material and dispersing the PI resin powder and hard particles, the extraction solvent is removed. A pore former formulation is obtained. Next, this pore forming material composition is blended in a resin solvent and uniformly stirred.
(4) A method in which PI resin powder, pore forming material and hard particles are blended in a resin solvent and uniformly stirred.
(5) A method in which PI resin powder, pore-forming material and hard particles are blended in a resin solvent and stirred uniformly, and then the resin solvent is removed and pulverized to obtain a powdery resin coating composition.
In the resin coating composition, hard particles are blended as necessary. In addition, PTFE resin powder can be blended with the resin coating composition for the purpose of improving the friction and wear resistance.

In the above method, the method for dissolving the pore-forming material in the extraction solvent and dissolving or dispersing the other components is not particularly limited as long as it is a method that can be mixed in the liquid. A ball mill, an ultrasonic disperser, a homogenizer Examples thereof include a juicer mixer and a Henschel mixer. It is also effective to add a small amount of a surfactant in order to suppress separation of the dispersion. At the time of mixing, the amount of extraction solvent is ensured so that the pore-forming material is completely dissolved by mixing.
As a method for removing the extraction solvent, methods such as heat evaporation, vacuum evaporation, bubbling with nitrogen gas, dialysis, and freeze-drying can be used. Since the method is easy and the equipment is inexpensive, it is preferable to remove the extraction solvent by heat evaporation.

  The solid content concentration in the resin coating composition of the present invention is 5% by weight to 50% by weight, preferably 5% by weight to 40% by weight, and more preferably 5% by weight to 30% by weight. If the solid content concentration is less than 5% by weight, the number of treatment steps for excess resin solvent increases, which is disadvantageous in the process. When the solid content concentration exceeds 50% by weight, the solid content amount is too large, and it becomes easy to cause nozzle clogging in an atomizing means such as a spray gun.

  Various methods such as a dipping method, a roller coating method, a brush coating method, a spray coating method, and a printing coating method can be adopted as a method of applying the resin coating composition of the present invention to the outer peripheral surface of the sliding member. Among these methods, when the accuracy of the film thickness of the coating film on the sliding member is required, a spray coating method capable of spraying a mist-like coating liquid on a part of the outer peripheral surface of the sliding member is preferable.

  As a method for removing the resin solvent from the sliding member coated with the resin coating composition of the present invention, methods such as heat evaporation, vacuum evaporation, bubbling with nitrogen gas, dialysis, and lyophilization can be used. Since the technique is easy and the equipment is inexpensive, it is preferable to remove the resin solvent by drying with heat evaporation. The drying temperature is preferably maintained in the range of 5 ° C to 100 ° C for 10 minutes to 2 hours. Thereby, foaming of the coating film used as a coating layer after baking can be suppressed.

  The dried coating is then baked. The firing temperature is a temperature lower than the melting point of the pore forming material to be used, and a temperature range of 150 ° C. to 450 ° C. is appropriate. When sodium benzoate (melting point: 430 ° C) is used as the pore forming material, the firing temperature is 150 ° C to less than 430 ° C. When the temperature is lower than 150 ° C., the curing reaction of the binder resin or the like often does not proceed. The firing is preferably divided into several stages such as 80 ° C. to 130 ° C. to 180 ° C., and gradually raised to the firing temperature every 30 minutes to 120 minutes within a range of 30 minutes to 240 minutes. Thereby, the curing reaction of the binder resin or the like proceeds gradually and reliably, and a coating layer having uniform adhesion strength can be formed. In addition, it is possible to prevent the occurrence of itchiness, wrinkles, wrinkles, cracks and the like in the coating layer. The maximum temperature holding time during firing may be in the range of 15 to 60 minutes, preferably 30 to 45 minutes. If the maximum temperature holding time is less than 15 minutes, the curing reaction of the binder resin, etc. is insufficient. Become more. Furthermore, the manufacturing process takes longer time, which increases the cost.

  The cooling after the firing process may be performed through a step opposite to that during the firing process, or may be gradually gradually cooled over a period of about 60 to 180 minutes. By slowly cooling in this way, the coating layer and the sliding member base material shrink uniformly and accurately, and a highly accurate sliding member can be obtained. The total firing time may be adjusted to about 2 to 10 hours.

  The porous resin film formed on the surface of the sliding member of the present invention is to wash the coating layer using an extraction solvent that dissolves the pore-forming material contained in the coating layer and does not dissolve the resin and hard particles. It can be obtained by extracting the pore forming material. For example, a water-soluble powder B having a melting point Y ° C. higher than X ° C. is blended with resin A having a firing temperature X ° C., fired at X ° C. to form a coating layer, and then the coating layer is washed with water. Thus, the water-soluble powder B is extracted to obtain a porous resin film. By performing this extraction treatment, the portion filled with the pore-forming material is dissolved, and after removal of the extraction solvent and drying, pores are formed in the portion filled with the pore-forming material to obtain a porous resin film. It is done.

  The layer thickness of the coating layer on the sliding member substrate thus obtained is preferably 5 to 50 μm. More preferably, it is 10-30 micrometers. If the thickness of the coating layer is too thin, it is not possible to sufficiently suppress abnormal noise and vibration during sliding due to an increase in the gap with the counterpart material, and if it is too thick, the adhesion of the coating layer may be inferior.

The surface coating formed on the surface of the sliding member can be used in a state where the porous resin coating is impregnated with lubricating oil in advance.
Examples of the lubricating oil that can be impregnated include spindle oil, refrigeration oil, turbine oil, machine oil, dynamo oil, paraffinic mineral oil, naphthenic mineral oil, and other mineral oils, polybutene, polyalphaolefin, alkylbenzene, alkylnaphthalene, and fat. Non-carbonized hydrocarbon synthetic oils such as cyclic compounds, or natural oils and fats, polyol ester oils, phosphate esters, diester oils, polyglycol oils, silicone oils, polyphenyl ether oils, alkyl diphenyl ether oils, fluorinated oils, etc. Any commonly used lubricating oil such as a hydrogen-based synthetic oil can be used without any particular limitation.
In the above lubricating oil, as long as the purpose of the present invention is not impaired, an extreme pressure agent, an antioxidant, a rust inhibitor, a pour point depressant, an ashless dispersant, a metal detergent, an interface Activators, wear modifiers, etc. can be blended. As the antioxidant, phenol, amine, sulfur and the like can be used alone or in combination.
In particular, since it is desired that the lubricating oil supplied from the porous resin film impregnated with the lubricating oil does not undergo oxidative degradation over a long period of time, it is preferable to incorporate the antioxidant as described above.
The impregnation method may be any method that can impregnate the porous resin coating. The pressure reduction impregnation in which the porous resin film is immersed in an impregnation tank filled with lubricating oil and then impregnated under reduced pressure is preferable. Further, when a high viscosity silicone oil or the like is used, it can be impregnated under pressure. It is good also as a pressure-reduced-pressure impregnation combining these.

  Since the coating formed on the surface of the sliding member of the present invention is a porous resin coating having 10% or more surface communication holes, an oil film is easily formed by the dimple effect due to the depression of the pores on the surface, and the sliding member Since the lubricating oil intrudes into the material during use, a good oil film can be formed even in a non-lubricated state at startup. Further, when the initial sliding characteristics are important, a more preferable result can be obtained by impregnating the lubricant in advance.

Example 1
Solid content volume ratio of 70:10:20 PAI resin varnish (HPC-4250-30 manufactured by Hitachi Chemical Co., Ltd.), spherical alumina (Admafine AQ-502 manufactured by Admatex Co., Ltd.), Benzo which is a pore forming material A resin coating composition obtained by mixing sodium acid powder (a reagent manufactured by Wako Pure Chemical Industries, Ltd.) for 5 minutes with a mixer was applied to a SUS304 disc of φ33 mm × 6 mm by dipping and dried (100 The film was fired (180 ° C. × 1 hour) to obtain a pore-forming material-containing coating film having a thickness of 50 μm. Thereafter, the pore-forming material-containing coating film was washed with warm water at 80 ° C. with an ultrasonic cleaner to elute the pore-forming material and dried to obtain a porous resin film test piece having a communication porosity of 38%.

Example 2
Solid content volume ratio of 70:10:20 PAI resin varnish (HPC-4250-30 manufactured by Hitachi Chemical Co., Ltd.), spherical alumina (Admafine AQ-502 manufactured by Admatex Co., Ltd.), Benzo which is a pore forming material A resin coating composition obtained by mixing sodium acid powder (a reagent manufactured by Wako Pure Chemical Industries, Ltd.) for 5 minutes with a mixer was applied to a SUS304 disc of φ33 mm × 6 mm by dipping and dried (100 The film was fired (180 ° C. × 1 hour) to obtain a pore-forming material-containing coating film having a thickness of 50 μm. Thereafter, the pore-forming material-containing coating film is washed with warm water of 80 ° C. with an ultrasonic cleaner to elute the pore-forming material, and dried to obtain a porous resin film-containing body having a communication porosity of 38%. Oil (Dexylon 2 manufactured by Showa Shell Sekiyu KK) was impregnated by a vacuum impregnation method to obtain a porous resin film test piece.

Example 3
Solid content volume ratio of 60: 10: 10: 20 PAI resin varnish (HPC-4250-30 manufactured by Hitachi Chemical Co., Ltd.), PTFE resin (Hostam Flon TF9207 manufactured by 3M Co., Ltd.), spherical alumina (Admatex Co., Ltd.) Admafine AQ-502) and sodium benzoate powder (reagent manufactured by Wako Pure Chemical Industries, Ltd.), which is a pore-forming material, were mixed in a mixer for 5 minutes to obtain a resin coating composition obtained by φ33 mm × 6 mm The SUS304 disc was coated by dipping, dried (100 ° C. × 30 minutes), and baked (180 ° C. × 1 hour) to obtain a pore-forming material-containing coating film having a thickness of 50 μm. Thereafter, the pore-forming material-containing coating film was washed with warm water at 80 ° C. with an ultrasonic cleaner to elute the pore-forming material and dried to obtain a porous resin film test piece having a communication porosity of 38%.

Example 4
Solid content volume ratio of 60: 10: 10: 20 PAI resin varnish (HPC-4250-30 manufactured by Hitachi Chemical Co., Ltd.), PTFE resin (Hostam Flon TF9207 manufactured by 3M Co., Ltd.), spherical alumina (Admatex Co., Ltd.) Admafine AQ-502) and sodium benzoate powder (reagent manufactured by Wako Pure Chemical Industries, Ltd.), which is a pore-forming material, were mixed in a mixer for 5 minutes to obtain a resin coating composition obtained by φ33 mm × 6 mm The SUS304 disc was coated by dipping, dried (100 ° C. × 30 minutes), and baked (180 ° C. × 1 hour) to obtain a pore-forming material-containing coating film having a thickness of 50 μm. Thereafter, the pore-forming material-containing coating film is washed with warm water of 80 ° C. with an ultrasonic cleaner to elute the pore-forming material, and dried to obtain a porous resin film-containing body having a communication porosity of 38%. Oil (Dexylon 2 manufactured by Showa Shell Sekiyu KK) was impregnated by a vacuum impregnation method to obtain a porous resin film test piece.

Example 5
Solid resin volume ratio of 60: 10: 10: 20 PI resin varnish (U-Vanice-A manufactured by Ube Industries, Ltd.), PTFE resin (3M Co., Ltd. hostaflon TF9207), spherical alumina (manufactured by Admatechs Co., Ltd.) A resin coating composition obtained by mixing Admafine AQ-502) and sodium benzoate powder (reagent manufactured by Wako Pure Chemical Industries, Ltd.), which is a pore-forming material, with a mixer for 5 minutes, has a diameter of 33 mm x 6 mm. An operation of applying to a SUS304 disk by dipping, drying (100 ° C. × 30 minutes), and baking (350 ° C. × 1 hour) was repeated twice to obtain a pore-forming material-containing coating film having a thickness of 50 μm. Thereafter, the pore-forming material-containing coating film was washed with warm water at 80 ° C. with an ultrasonic cleaner to elute the pore-forming material and dried to obtain a porous resin film test piece having a communication porosity of 38%.

Example 6
Solid resin volume ratio of 60: 10: 10: 20 PI resin varnish (U-Vanice-A manufactured by Ube Industries, Ltd.), PTFE resin (3M Co., Ltd. hostaflon TF9207), spherical alumina (manufactured by Admatechs Co., Ltd.) A resin coating composition obtained by mixing Admafine AQ-502) and sodium benzoate powder (reagent manufactured by Wako Pure Chemical Industries, Ltd.), which is a pore-forming material, with a mixer for 5 minutes, has a diameter of 33 mm x 6 mm. An operation of applying to a SUS304 disk by dipping, drying (100 ° C. × 30 minutes), and baking (350 ° C. × 1 hour) was repeated twice to obtain a pore-forming material-containing coating film having a thickness of 50 μm. Thereafter, the pore-forming material-containing coating film is washed with warm water of 80 ° C. with an ultrasonic cleaner to elute the pore-forming material, and dried to obtain a porous resin film-containing body having a communication porosity of 38%. Oil (Dexylon 2 manufactured by Showa Shell Sekiyu KK) was impregnated by a vacuum impregnation method to obtain a porous resin film test piece.

Comparative Example 1
PAI resin varnish (HPC-4250-30 manufactured by Hitachi Chemical Co., Ltd.), spherical alumina (Admafine AQ-502 manufactured by Admatex Co., Ltd.), PTFE resin powder (3M (solid content volume ratio 80:10:10) The resin coating composition obtained by mixing for 5 minutes with hostaflon TF9207) manufactured by Co., Ltd. was applied to a SUS304 disc of φ33 mm × 6 mm by dipping and dried (100 ° C. × 30 minutes) Firing (180 ° C. × 1 hour) was performed to obtain a resin mixture-coated specimen having a thickness of 50 μm.

The sliding characteristics of the porous resin film test pieces obtained in Example 1 and Example 6 and the resin mixture-coated test piece obtained in Comparative Example 1 were evaluated by the following methods. The results are shown in Table 1.
Sliding test in oil:
In order to investigate the friction and wear characteristics in oil, a ring-on-disk test was conducted under the following test conditions.
Oil: Automatic transmission oil (Dexylon 2 from Showa Shell Sekiyu KK)
Surface pressure: 5.5 MPa, speed: 64 m / min, time: 5 hours Specimen: φ33 mm × 6 mm, film thickness: 50 μm
Mating material: φ17 mm × φ21 mm × 10 mm, SUJ2 (surface roughness Ra 0.5μm)
Measurement item: Specific wear (× 10 ^-8 mm ³ / (N · m))
Lubrication-free sliding test:
In order to investigate the friction and wear characteristics without lubrication, a ring-on-disk test was conducted under the following test conditions.
Surface pressure: 5.5 MPa, speed: 64 m / min, time: 30 minutes Test piece: φ33 mm x 6 mm, film thickness: 50 μm
Mating material: φ17 mm × φ21 mm × 10 mm, SUJ2 (surface roughness Ra 0.5μm)
Measurement item: Specific wear (× 10 ^-8 mm ³ / (N · m))

油中摺動試験において、連通孔率 38％のＰＡＩ多孔質樹脂被膜試験片である実施例１、実施例３および実施例５は、ＰＡＩ樹脂およびＰＴＦＥ樹脂の混合体被覆試験片である比較例１に比べて、摩耗量が 70％〜80％減少し、良好な摩耗特性を示した。これは、比較例１では摺動部材自体に潤滑油を取り込む機能がないため、摺動面への潤滑油の供給が、摺動面に潤滑油が接触する微細な間隙に限定され、微量に留まることに対し、実施例１、実施例３および実施例５では摺動部材が保有する連通孔によって油中から潤滑油を取り込むとともに、取り込んだ潤滑油を連通孔を経由して摺動面に十分供給することができるために、摩耗量が少なくなることによると考えられる。また、ＰＡＩ多孔質樹脂被膜試験片にあらかじめ、潤滑油を含浸した実施例２、実施例４および実施例６の摩耗量は、実施例１、実施例３および実施例５の摩耗量に比べて 25％〜33％減少した。これはあらかじめ含浸された潤滑油が摺動初期段階から摺動面に供給されるために、摺動特性がさらに向上するものと考えられる。
無潤滑摺動試験において、実施例２、実施例４および実施例６は比較例１に比べて、摩耗量が 88％〜93％減少した。これは無潤滑摺動状態では、比較例１が配合物自体の潤滑性に留まることに対し、実施例２、実施例４および実施例６ではあらかじめ多孔質樹脂被膜に潤滑油を保有しているために、摺動面への潤滑油の供給が連通孔を経由して十分になされることにより、優れた摺動特性が得られるものと考えられる。
また、ＰＴＦＥ樹脂をＰＩ系樹脂と併用する場合は、ＰＩ系樹脂単独の場合に比べて、耐摩擦摩耗特性の向上が認められた。これはＰＴＦＥ樹脂の潤滑性が寄与しているものと考えられる。

In the sliding test in oil, Example 1, Example 3 and Example 5 which are PAI porous resin film test pieces having a communication porosity of 38% are comparative examples which are test pieces coated with PAI resin and PTFE resin. Compared to 1, the amount of wear decreased by 70% to 80%, indicating good wear characteristics. This is because, in Comparative Example 1, the sliding member itself does not have a function of taking the lubricating oil, so the supply of the lubricating oil to the sliding surface is limited to a minute gap where the lubricating oil contacts the sliding surface, In contrast, in Example 1, Example 3 and Example 5, the lubricating oil is taken in from the oil through the communication hole held by the sliding member, and the taken lubricating oil is transferred to the sliding surface via the communication hole. This is considered to be due to a decrease in the amount of wear because it can be supplied sufficiently. Further, the wear amount of Example 2, Example 4 and Example 6 in which the PAI porous resin film test piece was impregnated with the lubricating oil in advance was compared with the wear amount of Example 1, Example 3 and Example 5. 25% to 33% decrease. This is presumably because the pre-impregnated lubricating oil is supplied to the sliding surface from the initial stage of sliding, so that the sliding characteristics are further improved.
In the non-lubricated sliding test, the amount of wear in Examples 2, 4 and 6 was reduced by 88% to 93% compared to Comparative Example 1. This is because in the non-lubricated sliding state, Comparative Example 1 remains the lubricity of the formulation itself, whereas in Examples 2, 4 and 6, the porous resin coating has a lubricating oil in advance. Therefore, it is considered that excellent sliding characteristics can be obtained when the lubricating oil is sufficiently supplied to the sliding surface via the communication hole.
In addition, when PTFE resin was used in combination with PI resin, an improvement in friction and wear resistance was recognized as compared with the case of PI resin alone. This is considered to be due to the lubricity of the PTFE resin.

In the sliding member of the present invention, a porous resin film having a communication porosity of 10% or more is formed on the surface, and the porous resin film is impregnated with lubricating oil through the communication holes and applied to the sliding surface. Since the lubricating oil can be supplied, it can be suitably used as a sliding member that requires high strength and long-term lubricity.
In addition, because of its high seizure resistance, air-cooled engines or oil-cooled lawn mowers, mowers, welders, small generators, etc., which have a cooling capacity lower than that of water-cooled as well as automobiles and motorcycles, have small strict lubrication conditions. Can be suitably used for pistons used in general-purpose internal combustion engines, air compressors, actuators, and the like.

Claims (4)

  A sliding member having a surface coating formed on at least a sliding portion of a surface of a substrate, wherein the surface coating is a porous resin coating having a communicating porosity of 10% or more. Moving member.   The porous resin coating is a coating layer containing a resin, a pore-forming material, and hard particles, and then the coating using an extraction solvent that dissolves the pore-forming material and does not dissolve the resin and hard particles. The sliding member according to claim 1, further comprising a communication hole obtained by extracting the pore forming material from a layer.   The sliding member according to claim 2, wherein the communication hole is impregnated with lubricating oil.   A resin coating composition for forming a porous resin film, comprising a resin, a pore-forming material, and hard particles, wherein the pore-forming material is formed after coating film formation. A resin coating composition, which is a substance extracted by an extraction solvent that dissolves and does not dissolve the resin and hard particles.