JP2012149230A - Sliding member and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sliding member having a sliding surface, the sliding surface being provided with a solid lubricating film which shows excellent lubrication characteristics as low as liquid lubrication but has a gumless surface.SOLUTION: The sliding surface is coated with the lubricating film composed of an ultraviolet curable resin including lubricant-containing polyolefin resin particles. At least part of the resin particles is exposed to the surface of the lubricating film. The lubricating film can be produced by applying a mixture including polyolefin resin particles mixed to an ultraviolet curable resin coating material onto the sliding surface; curing the film by ultraviolet irradiation after the lapse of a retention time as needed; applying a lubricant to a resulting cured film; and heating it to a temperature higher than the melting point of the polyolefin resin to dissolve the lubricant to the resin particles exposed to the film surface.

Description

  The present invention is an extremely high-sliding coating having a sliding surface with a lubricating coating showing a low friction similar to that of liquid lubrication such as lubricating oil while being a non-sticky solid coating mainly composed of an ultraviolet curable resin. The present invention relates to a sliding member exhibiting dynamic characteristics and a manufacturing method thereof.

  The ultraviolet curable resin coating can form a coating in a short time without requiring heating of the coated substrate. Focusing on this point, the application of an ultraviolet curable resin coating to the formation of a lubricating film on the sliding surface of the sliding member has been studied.

  However, the UV curable resin coating has low lubricity, and even if it is used as a sliding member with the sliding surface covered with this coating, the sliding surface shows high friction, and eventually the coating wears and peels off. Resulting in. Therefore, it has been desired to reduce the friction of the ultraviolet curable resin coating.

  The reduction in friction of the sliding member is a performance desired from the viewpoint of energy saving. In terms of low friction, the combination of solid lubrication and liquid lubrication, such as applying a lubricating oil on the solid lubricant film, is superior to the case of only the solid lubricant film. However, the use of a liquid causes low friction, but has a drawback in that it easily flows out to the surroundings because of its high fluidity, contaminates the periphery of the sliding portion, and must be periodically replenished. In addition, since liquid is sticky, liquid lubrication is easily affected by contaminants such as adhesion of dust. Therefore, there is a demand for a sliding member that has a lubricating coating that has the advantages of solid lubrication and liquid lubrication, while having the effect of reducing oil friction while being solid.

  In JP-A-11-63132 (Patent Document 1) and 11-223260 (Patent Document 2), a member of a lubricating oil-containing polymer (also referred to as an oil-containing polymer) is disposed in the vicinity of a lubricating ball screw or a bearing. However, it is disclosed that the lubricating oil is continuously supplied by oozing from the member.

  The lubricating oil-containing polymer is a solid material composed of a lubricating oil and a thermoplastic organic polymer and forming a single phase in which both are compatible with each other. In particular, the polyolefin resin can contain a large amount of lubricating oil, and among them, the combination of polyethylene and mineral oil can contain as much as 70% of the total weight of the lubricating oil. Lubricating oil contained in the polymer exerts a lubricating action by moving from the inside of the material to the surface layer and oozing out by factors such as sliding, temperature rise, and pressure.

This lubricating oil-containing polymer is manufactured as a molded body (eg, sheet, columnar, etc.) by heating and melting a mixture of the raw organic polymer and lubricating oil, pouring the mixture into a predetermined mold, and cooling and solidifying it while applying pressure. It has been. Therefore, the conventional lubricating oil-containing polymer has a small degree of freedom in shape, and cannot form a film on the surface of the sliding surface of the sliding member as it is. Even if a film can be formed, the lubricant-containing polymer has low adhesion to the metal substrate, so even if it is applied as a lubricating film, the film is largely peeled off due to frictional resistance during sliding. It cannot be used as a sliding member.
JP-A-11-63132 JP-A-11-223260

  The present invention relates to a sliding member provided with a lubricating coating on a sliding surface, which is a solid coating with no stickiness on the surface, but which can exhibit a friction coefficient (sliding characteristic) as low as liquid lubrication, and a method for producing the same. It is an issue to provide.

  The inventors of the present invention have disclosed a lubricant-containing polymer in which a lubricant oil-containing particle is contained in an ultraviolet curable resin film, for example, as disclosed in Patent Documents 1 and 2 described above, in which a lubricant is contained in a polyolefin resin. It was found that the above-mentioned problems can be solved by dispersing particles in the form of particles, and the present invention has been achieved.

  The present invention is a sliding member having a sliding surface, wherein the sliding surface is coated with a lubricating coating made of an ultraviolet curable resin containing lubricating oil-containing particles, and at least a part of the particles is the lubricating member. The sliding member is exposed on the surface of the coating. The lubricating oil-containing particles exposed on the surface of the lubricating coating preferably protrude from the surface of the lubricating coating.

  Here, the “sliding member” means a member having a sliding surface such as a bearing, a piston, a cylinder, and a drive shaft. The material of the sliding member is typically steel or other metal, but the material is not limited to metal.

  The sliding surface of the sliding member on which the lubricating film is formed according to the present invention may be an untreated surface of the raw material as it is, but an appropriate surface treatment has been applied in advance for ensuring corrosion resistance and other purposes. It may be the surface. Examples of such surface treatment include various chemical conversion treatments such as plating (eg, zinc-based plating) and phosphate treatment, and two or more kinds of surface treatments can be combined.

  In a preferred embodiment, the lubricating oil is one or two selected from mineral oil and poly α-olefin oil, or one selected from ether oil, ester oil, extreme pressure additive and highly basic organic acid metal salt. Or it is 2 or more types.

  Lubricating oil-containing particles are, for example, materials in which porous particles such as porous ceramic particles are impregnated with lubricating oil and the pores of the porous particles are filled with lubricating oil, or microcapsules in which lubricating oil is enclosed. Also good. For example, by selecting a porous ceramic having a pore size suitable for impregnation with a lubricating oil and impregnating the porous ceramic with the porous ceramic particle, lubricating oil-containing porous ceramic particles that can be used in the present invention can be produced. . In this type of lubricating oil-containing particles, the lubricating oil is not compatible with the particulate material, so the lubricating oil remains liquid. However, even in this case, since most of the lubricating oil is present inside the particles, there is almost no stickiness on the coating surface.

  Preferred lubricating oil-containing particles are lubricating oil-containing resin particles in which lubricating oil is compatible with organic resin particles, and among them, lubricating oil-containing polyolefin resin particles in which lubricating oil is contained in polyolefin resin particles. Polyethylene is preferred as the polyolefin resin. The lubricating oil-containing organic resin is a solid material that forms a single phase in which the lubricating oil and the thermoplastic organic resin are compatible with each other, and the lubricating oil is also in a solid state. Therefore, the stickiness of the coating surface is eliminated despite containing the lubricating oil.

  When the lubricating oil-containing particles are lubricating oil-containing polyolefin resin particles, an ultraviolet curable resin film containing polyolefin resin particles not containing the lubricating oil is first formed, and then the lubricating oil is applied to the film, and then the resin particles By heating to a temperature at which the resin melts, the lubricating oil is made to be compatible with the polyolefin resin exposed on the surface of the coating, whereby the lubricating oil-containing polyolefin resin can be formed after the coating is formed. By doing so, only the polyolefin resin particles exposed on the coating surface can be used as the lubricating oil-containing resin particles, and the remaining polyolefin resin particles existing in the coating film can be left as they are.

  Specifically, the step of mixing the ultraviolet curable resin paint and the polyolefin resin particles so that the particles are dispersed in the paint to produce a mixed solution, and the sliding surface of the sliding member having the sliding surface The mixed liquid is applied to the film, and the coating film is cured by ultraviolet irradiation to form a cured resin film comprising an ultraviolet curable resin containing polyolefin resin particles, wherein at least a part of the resin particles are exposed on the coating surface. A step of forming and applying a lubricating oil to the coating and heating to a temperature equal to or higher than the melting point of the polyolefin resin so that the lubricating oil is compatible with the particles exposed on the coating surface of the polyolefin resin particles and lubricated. The sliding member which concerns on this invention can be manufactured by the method characterized by including the process of forming oil-containing particle | grains.

  When the lubricating oil has a high affinity with the polyolefin resin and easily dissolves, such as mineral oil or poly α-olefin oil, the lubricating oil is heated into the polyolefin resin particles by heating to the melting point of the used polyolefin resin. Can be compatible. On the other hand, when the lubricating oil has poor affinity with the polyolefin resin due to the difference in molecular structure and polarity, such as extreme pressure additive, highly basic organic acid metal salt, ether oil or ester oil The lubricating oil can be dissolved in the polyolefin resin particles by heating at a temperature higher than the melting point of the polyolefin resin, for example, 5 ° C. or higher.

  In the coating film forming step, after the mixed solution is applied to the sliding surface, the coating film is irradiated with ultraviolet rays after taking a holding time so that the polyolefin resin particles in the coating film float on the coating film surface. Is preferred.

  In the sliding member according to the present invention, the lubricating oil-containing particles that are exposed on the surface of the lubricating coating made of an ultraviolet curable resin, for example, the lubricating oil-containing polymer particles are in a state of normal temperature and atmospheric pressure before sliding, Since the solid particles themselves do not ooze out the lubricating oil, the coating surface is essentially dry and it is difficult for foreign matter to adhere to them. On the other hand, when sliding, due to frictional heat and high surface pressure, the liquid component (lubricating oil) oozes from the inside of the particles to the surface of the particles, and the lubricating oil oozed from the particles exposed to the coating surface causes By imparting the same low friction function, low friction characteristics similar to those of liquids can be exhibited despite the solid coating.

  As a result, the UV curable resin, which is inferior in lubrication and sliding performance but can be formed in a short time without using heating, is used as a film-forming component, and there is no stickiness on the surface except during sliding. Sometimes it is possible to realize a sliding member that can exhibit high lubrication and sliding performance. Since the sliding member of the present invention has extremely high lubrication performance, it can be advantageously applied to applications that undergo sliding at a particularly high surface pressure.

  In addition, according to the manufacturing method of the sliding member according to the present invention, the sliding member excellent in the adhesion of the lubricating coating is used for heating although the lubricating coating contains the lubricating oil-containing polyolefin resin. Without using an ultraviolet curable resin that can form a film in a short time.

Explanatory drawing regarding the manufacturing method of the sliding member which concerns on this invention. The graph which shows the result of the friction test in an Example and a comparative example with respect to the frequency | count of sliding. It is a 3D map image which shows the state of the friction surface before the sliding of the lubricating film of the sliding member which concerns on this invention (Example 4), and after a sliding. It is a 3D map image which shows the surface state of the lubricant film before and after the sliding in the comparative example 1 which formed the ultraviolet curable resin film which does not contain a resin particle.

The sliding member according to the present invention is characterized in that the sliding surface is coated with a lubricating coating made of an ultraviolet curable resin containing lubricating oil-containing particles in a dispersed state.
It is preferable that at least a part of the lubricating oil-containing particles is exposed on the surface of the lubricating coating. The lubricating oil-containing particles need not be uniformly distributed in the cross section in the thickness direction of the lubricating coating, and such a uniform distribution is not preferable. Instead, the lubricating oil-containing particles are not present at all in the vicinity of the interface with the sliding member in the cross section in the thickness direction of the lubricating coating, or the amount thereof is extremely small and concentrated near the surface of the lubricating coating on the opposite side. And at least part of the surface is preferably exposed on the surface, and more preferably protrudes from the surface. Thereby, the adhesiveness with the base material (sliding surface of a sliding member) of a lubricating film is fully ensured, ensuring high lubricity.

  The lubricating oil-containing particles may be particles such as microcapsules encapsulating lubricating oil, oil-containing porous carbon, oil-containing porous silica, and other oil-containing porous ceramics. Preferred are lubricating oil-containing organic resin particles, particularly lubricating oil. It is a containing polyolefin resin particle.

  The lubricating oil-containing polyolefin resin is composed of a lubricating resin and a polyolefin resin, which is a kind of thermoplastic resin, preferably polyethylene, and the mixture of the two is heated at a temperature equal to or higher than the melting point of the polyolefin resin to make them compatible. , Cooled to room temperature. The term “compatible” means that the lubricating oil and the polymer have an affinity for each other, so that they are completely mixed to form one phase. Therefore, it is preferable to select the lubricating oil and the resin so as to have a combination that has an affinity for each other and is easily compatible. Such a combination is when the lubricating oil is, for example, mineral oil or poly α-olefin oil, in which case the heating temperature may be the melting point of the polyolefin resin. That is, the heating temperature may be the same as the melting point. On the other hand, as the lubricating oil is an extreme pressure additive (or highly basic organic acid metal salt, ether oil or ester oil), the molecular structure and polarity are different from the polyolefin resin, and the resin-lubricating oil is poor in affinity. Even in the combination, the lubricating oil can be dissolved in the polyolefin resin by raising the heating temperature to a higher temperature.

  The granulation (powdering) of the lubricating oil-containing polyolefin resin is such that a mixture of the lubricating oil and the polyolefin resin is emulsified by stirring at a temperature equal to or higher than the melting point of the resin in a high-boiling liquid incompatible with the resin. Can be achieved in a way.

  However, as will be described later, in the preferred method for producing the sliding member of the present invention, by applying a mixed liquid of the ultraviolet curable resin paint and the polyolefin resin particles (not containing lubricating oil), A film in which polyolefin resin particles are dispersed is formed on the sliding surface of the sliding member, and a lubricating oil is applied to the film and heated to a temperature equal to or higher than the melting point of the polyolefin resin. Lubricating oil is mixed to form lubricating oil-containing polyolefin resin particles in the coating. In this method, the polyolefin resin particles that do not contain lubricating oil are used as raw materials, so that the material is easily available. In addition, polyolefin resin particles not containing lubricating oil are easy to handle and can be easily dispersed in the paint.

  Usable lubricants include poly α-olefin oil, mineral oil containing paraffinic hydrocarbon oil and naphthenic hydrocarbon oil, ether oil such as dialkyldiphenyl ether, ester such as phthalate ester and trimellitic acid ester High basic organic acid metal salts such as oil, tricresyl phosphate, zinc dialkyldithiophosphate, extreme pressure additives such as polysulfide, high basic Ca sulfonate, high basic Ca salicylate, high basic Ca phenate 1 type, or 2 or more types selected from these can be used.

  A highly basic organic acid metal salt is a salt composed of an organic acid, preferably an aromatic organic acid, and a stoichiometric excess of alkali (alkali metal or alkaline earth metal). In the present invention, this is included in the lubricating oil because the excess of the above is a grease-like substance at room temperature dispersed as colloidal fine particles. The metal salt may be an alkali metal salt, but preferably an alkaline earth metal salt, particularly a calcium salt. Those having a base number of 50 mgKOH / g or more are called highly basic.

  As the organic resin containing the lubricating oil, it is preferable to use a polyolefin resin that has been conventionally used in oil-containing polymers. Among these, polyethylene is preferable, and ultrahigh molecular weight polyethylene is more preferable. Ultra high molecular weight polyethylene means polyethylene having a weight average molecular weight of 1 million or more. Preferred ultra high molecular weight polyethylene is one having an average molecular weight in the range of 1.5 to 10 million.

  The polyolefin resin particles may be in any form such as a powder, a bead shape such as a spheroidized polymer, or a granular shape. The average particle size of the particles is preferably in the range of 5-50 μm. Examples of commercially available ultra-high purity polyethylene particles that can be used include miperon manufactured by Mitsui Chemicals.

  As the ultraviolet curable resin coating used for film formation, a resin composition composed of at least a monomer and / or oligomer and a photopolymerization initiator can be used. The ultraviolet curable resin coating forms an ultraviolet curable resin film when irradiated with ultraviolet rays after application. The ultraviolet curable resin coating is preferably a solventless composition that does not contain any solvent containing water, but a solvent-containing coating can also be used. Various ultraviolet curable resin coatings are commercially available, and they can be used as they are.

  Monomers used for UV curable resin coatings include various (meth) acrylate compounds, N-vinyl pyrrolidone, N-vinyl caprolactam, in addition to polyvalent (di or tri) esters of polyhydric alcohol and (meth) acrylic acid. And styrene. Examples of the oligomer include epoxy (meth) acrylate, urethane (meth) acrylate, polyester (meth) acrylate, polyether (meth) acrylate, and silicone (meth) acrylate.

  Useful photoinitiators are compounds having absorption at wavelengths between 260 and 450 nm, such as benzoin and its derivatives, benzophenone and its derivatives, acetophenone and its derivatives, Michler's ketone, benzyl and its derivatives, tetraalkylthiuram monosulfide And thioxanes. It is particularly preferable to use thioxanes.

  The ultraviolet curable resin coating may contain one or more additives selected from rust preventive additives, antioxidants, and lubricating powders as desired. As these additives, for example, those described in Toshio Sakurai “Physics of Lubricants” published by Koshobo can be applied.

  Specifically, alkenyl succinic acid derivatives and metal soaps are used as rust preventive additives, and DBPC (2,6-di-tert-butyl-paracresol) and M-DTP (metal metal dialkyldithiophosphate) are used as antioxidants. As the lubricating powder, molybdenum disulfide, tungsten disulfide, graphite, mica, boron nitride, polytetrafluoroethylene powder, and the like can be used. The content of the additive may be a conventional amount as described in the above-mentioned document, for example, and the appropriate amount varies depending on the type of additive.

  Next, the preferable manufacturing method of the sliding member which concerns on this invention is demonstrated, referring an accompanying drawing. FIG. 1 is an explanatory view schematically showing a method for manufacturing a sliding member according to the present invention. In the illustrated example, a case where a lubricating coating is formed according to the present invention on the surface of a steel sheet that has been surface-treated by zinc phosphate conversion treatment will be described as an example.

-Mixed liquid preparation process UV curable resin paint and polyolefin resin particles are mixed so that the particles are dispersed in the paint, and a mixed liquid used for coating is prepared. As described above, the ultraviolet curable resin paint is preferably a solvent-free resin composition composed of at least a monomer and / or oligomer and a photopolymerization initiator, and a commercially available ultraviolet curable resin paint can be used as it is. it can. If desired, appropriate additives may be further added. The polyolefin resin particles are preferably polyethylene particles, and more preferably ultra high molecular weight polyethylene particles.

  The ratio of the polyolefin resin particles is preferably 2 to 40 parts by mass with respect to 100 parts by mass of the ultraviolet curable resin paint (in the case of containing a solvent, based on the ultraviolet curable resin paint before solvent dilution). For mixing, for example, polyolefin resin particles are added to an ultraviolet curable resin coating, and the particles are sufficiently dispersed using an appropriate agitation / mixing means (eg, a stirrer equipped with rotating blades, a rotation reversal type agitation mixer, etc.). This can be done by continuing stirring until

・ Film formation process The liquid mixture prepared in the liquid mixture preparation process is applied to the sliding surface of a sliding member having a sliding surface, and the coating film is cured by ultraviolet irradiation, whereby a polyolefin resin is contained in the ultraviolet curable resin. A film in which the particles are dispersed is formed.

  The application can be performed using any conventional application means such as brush application or spray application, and an appropriate application means may be selected according to the shape of the sliding surface of the sliding member. The application is preferably performed so that the dry film thickness is in the range of 20 to 200 μm. This film thickness is preferably 0.5 times or more, preferably 2 times or more, more preferably 3 times or more the average particle diameter of the polyolefin resin particles used.

  It is preferable to take a short holding time after applying the ultraviolet curable resin coating / polyolefin resin particle mixture to the sliding surface of the sliding member without immediately irradiating with ultraviolet rays. This holding time may be, for example, 30 seconds to 15 minutes, preferably 2 to 10 minutes, for example, 5 minutes. As a result, as shown in FIG. 1, the polyolefin resin particles (shown as particularly preferred ultra-high molecular weight polyethylene particles in the figure) were uniformly distributed in the coating film immediately after application, whereas during the holding time, The polyolefin resin particles having a low specific gravity float up, and the polyolefin resin particles are unevenly distributed on the coating film surface. Therefore, there are few polyolefin resin particles in the vicinity of the interface with the base material, and there are many in the vicinity of the coating film surface on the opposite side, and the particle distribution becomes uneven in the thickness direction of the coating film. After this holding time, as shown in the drawing, at least a part of the particles existing in the vicinity of the surface of the coating film is exposed to the coating film surface. At this stage, the particles exposed on the coating film surface may protrude from the coating film surface as shown in the right figure.

  Depending on the combination of the polyolefin resin particles and the ultraviolet curable resin coating, the resin particles in the coating film described above can be used in a very short time (for example, 10 seconds) until the ultraviolet irradiation starts without taking such a special holding time. This retention time can be omitted in some cases.

  In some cases, after taking the above holding time, the coating film is irradiated with ultraviolet rays. This ultraviolet irradiation may be carried out by a well-known method and conditions commonly used for ultraviolet curable resin coatings. An appropriate ultraviolet wavelength or radiation source can be selected according to the type of the ultraviolet curable resin. The ultraviolet curable resin is cured by the ultraviolet irradiation, and the polyolefin resin particles are fixed in the cured film. In this way, a polyolefin resin-containing UV curable resin film is formed in which some polyolefin resin particles are exposed on the surface and optionally protrude from the surface.

・ Oil-impregnating treatment process After applying lubricating oil to the surface of the UV curable resin film containing polyolefin resin particles cured by UV irradiation as described above, the film is heated to a temperature equal to or higher than the melting point of the polyolefin resin used. Lubricating oil is mixed with the polyolefin resin particles exposed on the surface of the resin to form lubricating oil-containing resin particles containing the lubricating oil. This treatment is referred to as oil impregnation treatment in the present invention.

  The heating temperature may be equal to or higher than the melting point of the polyolefin resin when the lubricating oil has a high affinity with a polyolefin resin such as mineral oil or poly-α-olefin, and the lubricating oil is an extreme pressure additive (eg, tricresyl). Phosphate), highly basic organic acid metal salts, ether oils, ester oils and the like having a low affinity with a polyolefin resin, the temperature is higher than the melting point of the polyolefin resin, preferably higher than 5 ° C, more preferably Is heated to a high temperature of 10 ° C. or higher.

  Lubricating oil content varies depending on the amount of resin particles, especially the resin particles exposed on the surface and the oil impregnation performance of the resin particles. What is necessary is just to remove the lubricating oil which was not contained after the subsequent cooling.

  The lubricating oil may be applied by a conventional method such as brush application or spray application. Heating can be performed by known means such as heating by a heating furnace (oven), hot air heating, ultraviolet irradiation heat, and the like. Since the heating temperature is equal to or higher than the melting point of the polyolefin resin, the resin particles melt during the heating, but are separated from the other particles by the ultraviolet curable resin, so they solidify during the cooling after the heating and return to the particle shape. . The upper limit of the heating temperature is not particularly limited, but is preferably set to the melting point of the polyolefin resin + 40 ° C. or less in consideration of the heating cost. The heating time is sufficient if the lubricating oil is compatible with the resin particles in a sufficient amount, and varies depending on the heating temperature, the type of lubricating oil, etc., but generally within the range of 30 seconds to 30 minutes. Preferably, it is in the range of 1 to 10 minutes.

  Instead of heating after applying the lubricating oil, it is possible to apply the lubricating oil heated to a temperature considerably higher than the melting point of the polyolefin resin particles, thereby simultaneously performing the application and heating of the resin particles.

  As shown in FIG. 1, when the oil impregnation treatment including the application and heating of the lubricating oil is performed as described above, the lubricating oil selectively dissolves in the polyolefin resin particles exposed on the coating surface, thereby providing lubrication. Although it becomes oil-containing polyolefin resin particles (oil-containing resin particles in the figure), the resin particles present inside the coating are not compatible with the lubricating oil and remain as polyolefin resin particles. Therefore, the polyolefin resin particles exposed on the coating surface can be selectively made into oil-containing resin particles.

  The resin particles in which the lubricating oil is compatible solidify in the cooling process after heating, but the mass of the particles increases by the amount of the compatible lubricating oil, resulting in a particle having a larger particle size. For reasons such as this volume expansion, even particles that are only exposed on the surface of the coating but not protruding from the surface before the oil impregnation treatment often protrude from the surface of the coating after the oil impregnation treatment.

  Lubricating oil-containing polyolefin resin particles (oil-containing resin particles) that are concentrated on the surface and preferably protrude from the surface are contained under the action of high surface pressure and frictional heat during sliding. Oil oozes onto the particle surface. Thereby, the sliding member is given a high level of lubricity close to liquid lubrication. Therefore, the entire coating functions as a lubricating coating with excellent lubricity. However, since the oil-containing resin particles are solid particles when not sliding, the lubricating coating is a solid coating having a substantially non-sticky surface.

  In a preferred form, the oil-containing resin particles protrude from a smooth coating surface made of an ultraviolet curable resin. As a result, the sliding surface preferentially contacts with the oil-impregnated resin particles protruding during sliding, and the oozing of the lubricating oil is promoted, and low friction comparable to liquid lubrication can be exhibited. In addition, the mating sliding surface is less likely to come into contact with the surface of the UV curable resin having low lubrication performance, and the roughness of both sliding surfaces can be suppressed, so that an increase in friction due to the roughness can also be prevented.

  On the other hand, since the resin particles are entirely floated in the coating film before the ultraviolet irradiation, the resin particles are not present in the vicinity of the interface between the coating film and the base material, or the amount thereof is extremely small. Unlike polyolefin oil-containing polyolefin resin particles, polyolefin resin particles that do not contain lubricating oil present in the coating do not significantly impair the adhesion of the coating even if they are in contact with the substrate. When the polyolefin resin particles to be present are not present at all or the amount thereof is decreased, the adhesion of the ultraviolet curable resin film is further improved. As a result, the lubricating film formed by the above-described method can achieve both high-level lubricity close to liquid lubrication and good adhesion to the substrate at a high level.

  As described above, the material, shape, application, etc. of the sliding member are not particularly limited. Therefore, the present invention can be applied to various sliding members having sliding surfaces that repeatedly receive sliding. Specific examples of such a sliding member include a bearing, a piston, a cylinder, and a drive shaft.

  Hereinafter, the present invention is illustrated by examples, but the examples do not limit the present invention. Table 1 summarizes some of the materials and conditions used, the friction coefficient, and the presence or absence of stickiness in Examples and Comparative Examples.

In the following examples, the properties of the formed lubricating coating were measured by the following method.
Lubricity:
The dynamic friction coefficient was measured when the sliding was repeated up to 150 times by the Bowden friction test (steel ball: SUJ-2, 3/16 ″, load 1000 gf, sliding speed 4 mm / sec). The dynamic friction coefficient measured at the 150th sliding is shown, and when the friction test is stopped halfway due to film peeling, the friction coefficient measured at the last sliding is displayed.

Stickiness:
Alumina abrasive particles (Morundum A43-F60 manufactured by Showa Denko KK) are placed on the sliding member in a sufficient amount until the sliding member disappears, and air is blown with compressed air of 3 bar from a position 150 mm away. The stickiness was visually judged by whether or not the residue remained.

Sliding trace analysis:
Laser friction was measured on the friction surface before and after repeated sliding in the Bowden test, and a 3D map was created.

Example 1
A commercially available metal plate (made by Nippon Parkerizing Co., Ltd.) with zinc phosphate conversion treatment applied to the steel plate surface is used as a base material, and a commercially available UV curable resin (manufactured by Nippon Kayaku Co., Ltd.) is used on one side of this base material. KYARAD HX-220, acrylate monomer) Ultra-high molecular weight polyethylene curable resin (Mitsui Chemical Co., Ltd. Mipelon XM220, particle size 30 μm, melting point 136 ° C.) added and dispersed in 5 wt% solvent-free UV curable resin The paint was applied using a doctor blade applicator. To the UV curable resin, 3 wt% each of DETX-S (2,4-diethylthioxanthone) and EPA (ethyl p-dimethylaminobenzoate) manufactured by Nippon Kayaku Co., Ltd. were added in advance as photopolymerization initiators and accelerators. Dispersion and defoaming of the ultrahigh molecular weight polyethylene powder, the photopolymerization initiator, and the accelerator were performed using a rotation and revolution type stirring mixer (ARE-250T, manufactured by Shintaro Awatori) (dispersion: 500 rpm, 15 Min; defoaming: 500 rpm, 15 min).

After taking the retention time of 5 minutes after application, using a concentrating mercury lamp, integral illuminance 9000 mJ / cm ^2, to cure the coating film was irradiated with ultraviolet rays to the coating film in peak intensity 152mW / cm ^2, group An ultraviolet curable resin film was formed on the material surface. The film thickness measured with an electromagnetic film thickness meter was 120 μm.

  Mineral oil (Diana Process Oil PW90) is applied to this coating in a sufficient amount, kept in a heating furnace at 136 ° C for 5 minutes, cooled to room temperature, wiped off excess oil with gauze, and contains oil-containing organic resin particles A sliding member provided with an ultraviolet curable resin coating was prepared.

  The friction coefficient of this sliding member was about 0.05, which was almost the same as the friction coefficient in liquid lubrication (Comparative Example 5). Further, even after sliding 150 times, no increase in the coefficient of friction and damage to the coating were observed, and good lubricating performance was shown (FIG. 2). Also, no stickiness was observed.

  In this lubricating coating, it was confirmed from the 3D map of the lubricating coating before sliding in the friction test that part of the oil-containing resin particles was exposed on the surface of the lubricating coating and protruded from the surface. Further, the ultra high molecular weight polyethylene resin particles exposed on the surface are oil-containing resin particles containing lubricating oil. Comparative Example 3 in which the lubricating oil was not applied and heated (that is, the oil-containing treatment) was not performed. Compared to the above, it is proved that the friction coefficient in the friction test is low, but the protruding length of the particles is increased before and after the oil impregnation treatment (that is, the protruding length of the particles compared to Comparative Example 3 This is also confirmed by the fact that This point was the same in Examples 2 to 6.

(Example 2)
Sliding provided with a lubricating coating composed of an ultraviolet curable resin coating containing oil-containing organic resin particles in the same manner as in Example 1 except that the heating temperature after applying mineral oil (Diana Process Oil PW90) was changed to 150 ° C. A member was created. From the 3D map of the lubricant film before sliding in the friction test shown in FIG. 3, it was confirmed that in the formed lubricant film, part of the oil-containing resin particles was exposed on the surface of the lubricant film and protruded from the surface. It was.

  The friction coefficient of this sliding member was about 0.05, which was almost the same as the friction coefficient in liquid lubrication (Comparative Example 5). Further, even after 150 times of sliding, the coefficient of friction increased and the film damage was not found, and good lubricating performance was shown (FIG. 2). There was no stickiness.

(Example 3)
In the same manner as in Example 1, an ultraviolet curable resin film was formed on the surface of the substrate. Excessive pressure additive TCP (tricresyl phosphate, manufactured by Mitsubishi Gas Chemical Co., Inc.) is applied onto this coating, held in a heating furnace at 150 ° C. for 5 minutes, cooled to room temperature, and excess oil is removed with gauze. A sliding member provided with an ultraviolet curable resin film containing oil-containing resin particles was wiped off.

  The friction coefficient of this sliding member was about 0.05, which was almost the same as the friction coefficient in liquid lubrication using the same lubricating oil (Comparative Example 6). Further, even after 150 times of sliding, no increase in friction coefficient and damage to the coating film were found, and good lubricating performance was shown (FIG. 2). There was no stickiness. In the formed lubricating coating, it was confirmed from the 3D map of the lubricating coating before sliding in the friction test that part of the oil-containing resin particles was exposed on the surface of the lubricating coating and protruded from the surface.

Example 4
Except that a mixed liquid in which 5 wt% of the same ultrahigh molecular weight polyethylene powder as in Example 1 was added and dispersed in an epoxy acrylic resin UV curable resin paint (solvent-free type) manufactured by China Paint Co., Ltd. was used as the UV curable resin paint. In the same manner as in Example 1, an ultraviolet curable resin film was formed on the substrate surface. The film thickness measured with an electromagnetic film thickness meter was 120 μm. Mineral oil (Diana Process Oil PW90) is applied on the coating, heated in a heating furnace at 150 ° C. for 5 minutes, and cooled to room temperature. The excess oil is wiped off with gauze and contains oil-containing resin particles. A sliding member provided with an ultraviolet curable resin film was prepared.

  The friction coefficient of this sliding member was about 0.05, which was substantially the same as the friction coefficient in liquid lubrication (Comparative Example 5). Further, even after 150 times of sliding, the coefficient of friction was not increased and the film was not damaged, showing good lubricating performance (FIG. 2). FIG. 3 shows the results of observation of the surface of the lubricating coating with a laser microscope before and after the friction test in which 150 times of sliding was repeated. After the friction test (after sliding), the protruding oil-impregnated resin particles remain on the surface of the lubricating coating, although the amount and height vary slightly, as before the friction test (before sliding). In addition, it was observed that the roughness of the flat surface of the coating composed of the ultraviolet curable resin was suppressed. Also, no stickiness of the film was observed. In the formed lubricating coating, it was confirmed from the 3D map of the lubricating coating before sliding in the friction test that part of the oil-containing resin particles was exposed on the surface of the lubricating coating and protruded from the surface.

(Example 5)
The UV curable resin was changed to another commercially available product (KAYARAD R-712, Nippon Kayaku Co., Ltd., acrylate monomer), and the UV irradiation conditions were changed to an integrated illuminance of 10,000 mJ / cm ² and a peak intensity of 50 mW / cm ^2. In the same manner as in Example 1, an ultraviolet curable resin film was formed on the substrate surface. The types and addition amounts of the curing agent, curing accelerator, and polyethylene powder were the same. The film thickness measured with an electromagnetic film thickness meter was 120 μm. Mineral oil (Diana Process Oil PW90) is applied on the coating, heated in a heating furnace at 150 ° C. for 5 minutes, and cooled to room temperature. The excess oil is wiped off with gauze and contains oil-containing resin particles. A sliding member provided with an ultraviolet curable resin film was prepared.

  The sliding member had a friction coefficient of about 0.05, which was the same as the friction coefficient in liquid lubrication (Comparative Example 5). Further, even after 150 times of sliding, the coefficient of friction was not increased and the film was not damaged, showing good lubricating performance (FIG. 2). There was no stickiness. In the formed lubricating coating, it was confirmed from the 3D map of the lubricating coating before sliding in the friction test that part of the oil-containing resin particles was exposed on the surface of the lubricating coating and protruded from the surface.

(Example 6)
An ultraviolet curable resin film was formed on the substrate surface in exactly the same manner as in Example 5 except that another ultrahigh molecular weight polyethylene powder (Mipelon PM200, Mitsui Chemicals, melting point 136 ° C., particle size 10 μm) was used. The film thickness measured with an electromagnetic film thickness meter was 120 μm. Mineral oil (Diana Process Oil PW90) is applied on the coating, heated in a heating furnace at 150 ° C. for 5 minutes, and cooled to room temperature. The excess oil is wiped off with gauze and contains oil-containing resin particles. A sliding member provided with an ultraviolet curable resin film was prepared.

  The sliding member had a friction coefficient of about 0.05, which was the same as the friction coefficient in liquid lubrication (Comparative Example 5). Further, even after 150 times of sliding, the coefficient of friction was not increased and the film was not damaged, showing good lubricating performance (FIG. 2). There was no stickiness. In the formed lubricating coating, it was confirmed from the 3D map of the lubricating coating before sliding in the friction test that part of the oil-containing resin particles was exposed on the surface of the lubricating coating and protruded from the surface.

(Comparative Example 1)
Using the same epoxy acrylic resin ultraviolet curable resin paint (solvent-free type) manufactured by China Paint Co., Ltd. used in Example 4, a sliding member provided with an ultraviolet curable resin film not containing resin particles was prepared. The metal plate, coating method, and curing method were the same as in Example 4. The friction coefficient of this sliding member immediately increased immediately after the start of sliding (FIG. 2), and as described below, the coating peeled off and worn out after sliding 10 times, and the friction test was stopped there. There was no stickiness of the coating.

  FIG. 4 shows the result of observing the surface of the coating film before and after sliding 10 times with a laser microscope in the friction test of the ultraviolet curable resin film not containing the resin particles. Before the friction test, the surface of the coating is smooth, and unlike FIG. 3, naturally, resin particles protruding from the surface of the coating are not observed. It can be seen from FIG. 4 that after sliding 10 times in the friction test, the surface of the coating is extremely rough due to friction and partial peeling of the coating occurs.

(Comparative Example 2)
Mineral oil (Diana Process Oil PW90) is applied to the sliding member produced in Comparative Example 1 and heated in a heating furnace at 150 ° C. for 5 minutes. After cooling to room temperature, the excess oil is wiped off with gauze. Thus, a sliding member provided with an ultraviolet curable resin film was prepared. The coefficient of friction of this sliding member immediately increased immediately after the start of sliding, and after 10 times of sliding, film peeling and abrasion occurred (FIG. 2). There was no stickiness of the coating.

(Comparative Example 3)
The ultraviolet curable resin film before being heated by applying mineral oil in Example 1, that is, the ultraviolet curable resin film containing ultrahigh molecular weight polyethylene resin particles not containing a lubricating oil, part of which protrudes from the film surface A sliding member provided with was also prepared, and the coefficient of friction was measured. The friction coefficient of this sliding member was about 0.3, and no increase in the friction coefficient was observed even after 150 times of sliding, but no decrease in the coating friction as achieved in the examples was observed ( Figure 2).

(Comparative Example 4)
In Example 1, an ultraviolet curable resin film before being heated by applying mineral oil was formed, and an extreme pressure additive TCP (manufactured by Mitsubishi Gas Chemical Co., Ltd.) was applied as a lubricating oil on this film. After holding for 5 minutes and cooling to room temperature, excess oil was wiped off with gauze to create a sliding member provided with an ultraviolet curable resin coating containing resin particles. The coefficient of friction of the sliding member gradually increased, and reached a high value of about 0.3 at the 150th sliding. Since the heating temperature after application of the extreme pressure additive, which is a lubricating oil having low affinity with the polyolefin resin, was low, the compatibility of the extreme pressure additive into the resin particles did not occur substantially, and the resin particles contained oil. It is presumed that the resin particles were not formed.
(Comparative Example 5)
The sliding characteristics of the sliding member obtained by applying normal temperature mineral oil (Diana Process Oil PW90) to the ultraviolet curable resin film of the sliding member of Comparative Example 3 were examined. The coefficient of friction was as low as about 0.05 (FIG. 2). However, since the liquid was present, the coating was largely sticky.

(Comparative Example 6)
The sliding characteristics of the sliding member obtained by applying a normal temperature extreme pressure additive TCP (Mitsubishi Gas Chemical Co., Ltd.) to the ultraviolet curable resin film of the sliding member of Comparative Example 3 were examined. The coefficient of friction was as low as about 0.05 (FIG. 2). However, since the liquid was present, the coating was largely sticky.

Claims (10)

  A sliding member having a sliding surface, wherein the sliding surface is coated with a lubricating coating made of an ultraviolet curable resin containing lubricating oil-containing particles, and at least a part of the lubricating oil-containing particles is the lubricating coating. A sliding member which is exposed on the surface of   The sliding member according to claim 1, wherein the lubricating oil-containing particles exposed on the surface of the lubricating coating protrude from the surface of the lubricating coating. The sliding member according to claim 1, wherein the lubricating oil-containing particles are organic resin particles in which lubricating oil is compatible.   The sliding member according to claim 3, wherein the organic resin particles are polyolefin resin particles.   The sliding member according to claim 4, wherein the polyolefin resin is polyethylene.   The sliding member according to any one of claims 1 to 5, wherein the lubricating oil is one or two selected from mineral oil and poly α-olefin oil.   The sliding member according to any one of claims 1 to 5, wherein the lubricating oil is one or more selected from an extreme pressure additive, a highly basic organic acid metal salt, an ester oil, and an ether oil. .   The step of mixing the ultraviolet curable resin paint and the polyolefin resin particles so that the particles are dispersed in the paint to prepare a mixed liquid, and the mixed liquid on the sliding surface of the sliding member having the sliding surface Applying and curing the coating film by ultraviolet irradiation, forming a cured resin film comprising an ultraviolet curable resin containing polyolefin resin particles, wherein at least a part of the resin particles are exposed on the coating surface; Lubricating oil is applied to the coating and heated to a temperature equal to or higher than the melting point of the polyolefin resin, so that the lubricating oil is mixed with the particles exposed on the coating surface of the polyolefin resin particles to form lubricating oil-containing particles. The manufacturing method of the sliding member of Claim 6 characterized by including these processes.   The step of mixing the ultraviolet curable resin paint and the polyolefin resin particles so that the particles are dispersed in the paint to prepare a mixed liquid, and the mixed liquid on the sliding surface of the sliding member having the sliding surface Applying and curing the coating film by ultraviolet irradiation, forming a cured resin film comprising an ultraviolet curable resin containing polyolefin resin particles, wherein at least a part of the resin particles are exposed on the coating surface; Lubricating oil is applied to the coating, and the lubricating oil is mixed with the particles exposed on the coating surface of the polyolefin resin particles by heating to a temperature 5 ° C. higher than the melting point of the polyolefin resin. The method for producing a sliding member according to claim 7, further comprising: forming particles.   In the coating film forming step, after applying the mixed liquid to the sliding surface, after taking a holding time so that a part of the polyolefin resin particles in the coating film floats on the coating film surface and is exposed to the surface, The method of Claim 8 or 9 which performs ultraviolet irradiation of a coating film.