Lubricating composition and a sliding member comprising the composition

Abstract: Disclosed herein are a lubricating composition comprising 5 to 65% by weight of a solid lubricant powder material, 5 to 20% by weight of a lubricating oil which is in a liquid or paste form at an ordinary temperature, 1 to 8% by weight of a carrier for absorbing and possessing said lubricating oil, 10 to 30% by weight of a thermoplastic resin, and 25 to 50% by weight of a thermosetting synthetic resin, and a sliding member comprising a metal substrate and a solid lubricant composed of the lubricating composition.

Description: BACKGROUND OF THE INVENTION The present invention relates to a lubricating composition containing a lubricating oil, particularly to a lubricating composition used as being charged or being charged and coated on metal substrates in various forms, and a sliding member composed of the lubricating composition. A sliding member in which a sliding surface of a metal substrate is charged and coated with a lubricating composition has been conventionally and widely used for various mechanical parts. Such members and the respective lubricating compositions are for example described in EP-A-0 469 906 and JP-A-55 139 429. As an example, it is explained so-called solid lubricant-embedding sliding members in which apertures or grooves are formed to a metal substrate made of copper alloys or iron alloys and a solid lubricant is embedded and fixed in such apertures or grooves, have been used for various kinds of machine parts. As a manufacturing method for the solid lubricant-embedding sliding member includes a method (1) of using a round graphite rod having spiral ridges formed at the outer circumferential surface as a core in a casting mold, casting a molten metal into the casting mold, and removing the core by the cutting, thereby exposing the solid lubricant (graphite) spirally to the sliding surface (Japanese Patent Publication No 39-2506 (1964)); a method (2) of adhering and fixing solid lubricant pellets (cylindrical form) to paper or film which is burnt to be eliminated upon casting of a molten metal adhering and fixing the obtained solid lubricant pellets to the outer circumferential surface of a core rod composed of a shell sand mold to form a core in the casting mold (Japanese Patent Publication No 56-14381(1981)), or adhering and fixing solid lubricant pellets to a core rod composed of a shell sand mold to form a core for the casting mold (Japanese Patent Publication No 52-5449(1977)), casting a molten metal into the casting mold, thereby exposing the solid lubricant pellets on the sliding surface; or a method (3) of forming apertures or grooves to a metal substrate and embedding and fixing solid lubricant pellets coated with adhesives into the apertures or grooves, may be cited. In the manufacturing methods described above, the method (1) has drawbacks that the molten metal can not extend sufficiently upon casting since graphite of good heat conductivity is used as it is for the core and the shape of the sliding member is restricted, and the method (2) has drawbacks that the solid lubricant pellets are detached or displaced during casting and it is difficult to obtain a sliding member in which the solid lubricant pellet are arranged regularly. Accordingly, the method (3) described in the above has been used generally. However, the method (3) also involves several technical problems. (a) Since the size of the apertures (aperture diameter) disposed in the metal substrate is different depending on the size of the metal substrates, the solid lubricant pellets embedded into such apertures having various sizes have to be prepared corresponding to the varying aperture thereof. (b) Since it is difficult to automate the operation of embedding the solid lubricant pellets coated with adhesives and it has to be done manually, the workability is extremely poor. (c) Since the solid lubricant pellets can not be used for embedding and fixing solid lubricant into grooves, for example, spiral grooves or ring-shaped grooves disposed in the inner surface of a metal substrate, in particular, a cylindrical metal substrate, it is necessary to provide a paste-like solid lubricant having a fluidity. Further, as an additional problem, skin eruption or like of other unexpected accident may occur to operators during coating operation of adhesives to the solid lubricants in view of the item (b) described above. Further, the following solid lubricants have been known: A lubricant containing heat-molded composition comprising a polymeric synthetic resinous base material blended with a lubricant adsorbent carrier, the carrier having a lubricant adsorbed thereon, and molded, the carrier having a melting point or a melt viscosity higher than the base material, having a surface area of at least 0.01 m 2 /g, and being selected from the group consisting of (1) a non-fusible inorganic material; (2) a synthetic high molecular weight polymeric resinous material; (3) a naturally occurring high molecular weight polymeric material; and (4) mixtures thereof; and the base material being selected from the group consisting of a polymeric synthetic resin and a mixture of at least two polymeric synthetic resins (U.S. Patent No. 3,778,918); A sliding surface embedding-type solid lubricant comprising a solid lubricant powder, a thermosetting synthetic resin or an ordinary temperature setting-type synthetic resin which is liquid under an ordinary temperature for bonding the powdery particles and a lubricating oil impregnated between each of the powdery particles bonded by the synthetic resin (Japanese Patent Application Laid-Open (KOKAI) No. 58-160398(1983)); A composite lubricating material which can be molded into a desired shape and have a high surface strength, comprising 0.5 to 90.0% by weight of a pulverized, surface-treated and expanded graphite product (a+b) obtained by subjecting from 5 to 99.5% by weight of an expanded graphite powder (a) having an apparent specific gravity of 0.01 to 0.50 obtained by wet oxidation of natural graphite, kish graphite and artificial graphite, and then expanding and disintegrating them under a high temperature heat treatment, to surface treatment with 0.5 to 95.0% by weight of a lubricating oil (b), for example, turbine oil, machine oil, spindle oil and bearing oil, and 10 to 99.5% by weight of an organic binder (c) composed of a thermosetting synthetic resin such as phenol resin, melamine resin, epoxy resin and polyimide resin, or a thermoplastic synthetic resin such as polyphenylene sulfide, polyacetal, polytetrafluoroethylene, nylon 6, nylon 11 and polyurethane (Japanese Patent Application Laid-Open (KOKAI) No. 63-23993(1988)); An extrudable or injection moldable self-lubricating composition comprising 100 parts by weight of a molding product composed of 99 to 10 parts by weight of a lubricating oil and 20 to 90 parts by weight of a super high molecular weight-polyethylene, and 0.1 to 20 parts by weight of a powder blended therewith (Japanese Patent Application Laid-Open (KOKAI) No. 63-161075(1988)); and A composite bearing material comprising 0.1 to 10% by weight of fiber material having a good affinity for oil, 1 to 15% by weight of lubricating oil and the remainder of synthetic resin, with which pores and surfaces of a porous metallic layer provided on a metallic backing are impregnated and coated (U.S. Patent No. 4,308,153). The composite bearing material disclosed in the U.S. Patent '153 may contain 0.1 to 10% by weight of a solid lubricant such as graphite and 0.1 to 10% by weight of a metallic soap. The U.S. Patent '153 also discloses a thermoplastic resin as the synthetic resin and the actually used synthetic resin was polyacetal. On the other hand, under the consideration of the performance of the sliding member, since the embedded solid lubricant is supplied little by little to the sliding surface to form a solid lubricant film, it can be served for the long time use without additionally supplying the lubricant. However, since the application use is substantially restricted to that in a low speed and high load region, the combined use with a lubricating oil is inevitable in an application use as being out of the above-mentioned region. In addition, the lubricant containing thermoplastic resin as disclosed in the patent '153 generally has low bonding strength to a metal substrate, resulting in detaching of the lubricant. Accordingly, in the solid lubricant-embedding sliding member to be applied outside the above-mentioned region, it is required to form grooves to the sliding surface as grease pits or to supply the lubricating oil from the oil feeding device to the sliding surface. For the foregoing problems in view of manufacture and performance, the present inventors have considered that the all of the problems described above can be overcome thoroughly by satisfying all of the technical subjects, namely, (1) the lubricating composition can be embedded without restrictions at all, to the size and the shape of the apertures or grooves disposed in the metal substrate, (2) the solid lubricant embedded can provide both the lubricating effect by the lubricating oil and the lubricating effect by the solid lubricant powder material and (3) the solid lubricant can be bonded to the apertures or grooves in the metal substrate. As a result of an earnest study, it has been found that by blending a solid lubricant powder material with a lubricating oil which is in a liquid or paste-like form at ordinary temperatures, a carrier for absorbing and possessing the lubricating oil, and a thermosetting synthetic resin binder, the thus-obtained lubricating composition has a wettability and a fluidity, and the solid lubricant obtained therefrom is bonded to the apertures or grooves disposed in the metal substrate even if it contains the lubricating oil. On the basis of the finding, the present invention has been attained. SUMMARY OF THE INVENTION In the first aspect of the present invention, there is provided a lubricating composition comprising 5 to 65% by weight of a solid lubricant powder material, 5 to 20% by weight of a lubricating oil which is in a liquid or paste form at an ordinary temperature, 1 to 8% by weight of a carrier for absorbing and possessing said lubricating oil, 10 to 30% by weight of a thermoplastic resin other than polytetrafluoro ethylene (PTFE) and 25 to 50% by weight of a thermosetting synthetic resin. In the second aspect of the present invention, there is provided a sliding member comprising a solid lubricant embedded into apertures or grooves of a metal substrate, said solid lubricant being obtained by flow-charging the lubricating composition defined in the first aspect into the apertures or grooves of the metal substrate and bonding the charged lubricating composition to the apertures or grooves of said metal substrate. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS Fig. 1 is a vertical cross sectional view of one embodiment of a flow charging device for a lubricating composition. Fig. 2 is a cross sectional view taken along line II-II in Fig. 1. Fig. 3 is a vertical cross sectional view illustrating a sliding member comprising a metal substrate and a solid lubricant charged therein and composed of a lubricating composition. DETAILED DESCRIPTION OF THE INVENTION In the present invention, the solid lubricant powder material is one having a solid lubricating function by itself. For example, one or more of materials selected from the group consisting of: (a) graphite, (b) fluorinated graphite, (c) molybdenum disulfide; (d) tungsten disulfide, (e) boron nitride; (f) calcium fluoride, (g) polytetrafluoroethylene (PTFE), (h) soft metals such as lead, tin, lead-tin alloy and indium, and (i) metallic soaps such as fatty acid salts of lithium, calcium, aluminum and barium may be used. Among them, fluorinated graphite, boron nitride, polytetrafluoroethylene (PTFE), soft metals are preferred. When fluorinated graphite, boron nitride, calcium fluoride, PTFE or metallic soap is used, since the thus-obtained lubricating composition has white colour, it is possible to colour a lubricating composition obtained by adding a slight amount of a colorant. By the coloured lubricating composition, undesirable image of black or gray colour of the solid lubricant in the sliding member used in fiber machines and food processing machines can be eliminated, resulting in giving a clean image to a sliding member. A solid lubricant powder material having an average grain size of not more than 150 µm, more preferably 80 to 130 µm is preferred. The blending amount of the solid lubricant powder material is determined as the balance of the lubricating oil, the carrier and the synthetic resin binder to be blended, and it is within a range from 5 to 65% by weight, preferably from 15 to 45% by weight. If the blending amount of the solid lubricant powder material is less than 5% by weight, it is difficult to have the sufficient lubricating effect of the solid lubricant powder material itself. Further, if the blending amount exceeds 65 % by weight, bonding strength of the solid lubricant to a metal substrate or mechanical strength of the solid lubricant tends to be lowered when a metal substrate is filled and covered with the lubricating composition. The lubricating oil which is liquid or paste under an ordinary temperature includes mineral oils such as machine oil and engine oil, vegetable oils such as castor oil, synthetic oils such as ester oil and silicone oil, and grease, and one or more of them are used. When the lubricating oil is mixed with the solid lubricant powder material described above and the carrier for absorbing and possessing the lubricating oil, most of the lubricating oil is absorbed and possessed in the carrier and a portion thereof is adsorbed and retained at the surface of the solid lubricant powder material. The blending amount of the lubricating oil is from 5 to 20% by weight, preferably from 8 to 15% by weight. If the blending amount is less than 5% by weight, although the bonding strength of the solid lubricant to the apertures or the grooves in the metal substrate is increased, the bleeding amount of the lubricating oil to the sliding surface is reduced, thereby failing to obtain an improvement for the sliding performance by the lubricating oil. If it is blended in excess of 20% by weight, the amount of the lubricating oil in the solid lubricant is increased and the lubricant oil is present at the bonding boundary between the solid lubricant and the apertures or the grooves in the metal substrate to weaken the bonding strength of the solid lubricant with the apertures or grooves in the metal substrate, thereby bringing about a defect in which the solid lubricant is drawn out from the apertures or the grooves in the metal substrate. The carrier is blended with the solid lubricant powder material and the lubricating oil described above, and it has a characteristic of an absorbing and possessing the lubricating oil. The carrier has a function of absorbing and possessing the lubricating oil, thereby increasing the flow viscosity of the lubricating oil, preventing bleeding out of the lubricating oil, and is connectively dispersed in the solid lubricant, thereby supplying the lubricating oil to the sliding surface. The carrier usable in the present invention includes (1) hydrocarbon wax, (2) a higher fatty acid, (3) a wax of a derivative of a higher fatty acid, (4) oleophilic fiber, (5) crosslinked porous spherical particles mainly composed of styrene or methacrylic compound, (6) porous calcium carbonate, (7) phenol carbide resin and (8) a rubber oil-absorbing material. Among them, the hydrocarbon wax, and the higher fatty acid are preferred. They may be used alone or as a mixture of two or more of them. (1) Hydrocarbon Wax: The hydrocarbon wax includes a paraffin wax having not less than 24 of carbon atoms, an olefin wax having not less than 26 of carbon atoms and an alkylbenzene having not less than 28 of carbon atoms, and in addition, a microcrystalline wax can also be used. (2) Higher Fatty Acid: As the higher fatty acid, there can be mentioned a saturated fatty acid having not less than 14 o carbon atoms, for example, myristic acid, palmitic acid, stearic acid, arachic acid and montanic acid, as well as an unsaturated fatty acid having not less than 18 of carbon atoms, for example, octadecenic acid and parinaric acid. (3) Wax of Derivative of Higher Fatty Acid: As the wax, there can be mentioned, for example, (a) a higher fatty acid ester, (b) a higher fatty acid amide and (c) a higher fatty acid salt. (a) Higher fatty acid ester: As the higher fatty acid ester, there can be mentioned a methyl and ethyl ester of higher fatty acid having not less than 22 of carbon atoms, for example, ethyl behenate and methyl tricosane; an ester of a mono-valent higher fatty acid having not less than 16 of carbon atoms and a higher monohydric alcohol having not less than 15 of carbon atoms, for example, octadecyl stearate; a mono- or di-glycerine ester of higher fatty acid having not less than 13 of carbon atoms, for example, 1,3-dilauric acid glyceride and monostearic acid glyceride; and a triglyceride of higher fatty acid having not less than 14 of carbon atoms. (b) Higher fatty acid amide: As the higher fatty acid amide, there can be mentioned, in particular, palmitic acid amide, stearic acid amide and oleic acid amide. (c) Higher fatty acid salt: As the higher fatty acid salt, there can be mentioned a salt with alkali and alkaline earth metal, for example, lithium stearate and calcium stearate. (4) Oleophilic Fiber: As the oleophilic fiber, there can be mentioned a cellulose fiber and a polypropylene fiber. (5) Crosslinked porous spherical particles mainly composed of styrene or methacrylic material: As the porous spherical particles, there can be mentioned, for example, styrene-divinylbenzene copolymer. (6) Porous Calcium Carbonate. (7) Phenol Carbide Resin: As the phenol carbide resin, there can be mentioned one having a carbon content of 94 to 99.8%, which is carbonized by heating resol resin or novolak resin at 1000 to 2000°C in nitrogen gas atmosphere. (8) Rubber Oil-absorbing Material: As the rubber oil-absorbing material, there can be mentioned polyisobutylene, polybutadiene, styrenebutadiene copolymer rubber, ethylene-propylene copolymer rubber, ethylene-propylene terpolymer and polynorbornene synthetic elastomer. The blending amount of the carrier is determined depending on the amount of the lubricating oil, and is generally from 1 to 8% by weight, preferably 1.6 to 6% by weight. A preferred combination can be obtained for the bonding strength of the solid lubricant to the apertures or the grooves in the metal substrate and the lubricating property by setting the amount of the carrier toward the lower limit when the lubricating oil to be blended is on the side of the lower limit, whereas by setting the blending amount of the carrier toward the upper limit when the blending amount of the lubricating oil is on the side of the upper limit. The thermoplastic synthetic resin is added to the lubricating composition described above for enhancing the strength of the solid lubricant which is embedded into metal substrates in various forms and for enhancing the effect as a binder of the thermosetting synthetic resin binder. The thermoplastic synthetic resin which does not tend to impair the lubricating properties of the solid lubricant and the lubricating oil in the lubricating composition is preferably used. The preferred thermoplastic synthetic resin includes aliphatic polyamide such as nylon 6, nylon 66, nylon 11 and nylon 12, aromatic polyamide, polyacetal, polyether ether ketone (PEEK), polyphenylene sulfide (PPS), polybutyrene terephthalate (PBT) and oxybenzoyl polyester. One or more of the thermoplastic synthetic resins may be used. The thermoplastic synthetic resin may be used in a powder form, a fiber form or a woven fabric tip form, depending on the intended use. The blending amount of the thermoplastic synthetic resin is generally from 10 to 30% by weight, preferably 10 to 20% by weight. If the blending amount of the thermoplastic resin is less than 10% by weight, it is difficult to attain the above-mentioned effect of the addition of the thermoplastic synthetic resin. Further, if the blending amount exceeds 30% by weight, the lubricating properties of the solid lubricant powder material and the lubricating oil in the solid lubricant tends to be impaired. The thermosetting synthetic resin binder has roles of bonding the solid lubricant powder materials to each other and of bonding the solid lubricant with the apertures or the grooves in the metal substrate. As the synthetic resin binder, there can be mentioned a thermosetting synthetic resin such as epoxy resin, modified epoxy resin, phenol resin, phenoxy resin and alkyd resin, and the epoxy resin is preferred in the present invention. As the epoxy resin, an ordinary temperature-setting liquid epoxy resin and a thermosetting liquid or powdery epoxy resin is used. Specifically, as the ordinary temperature-setting epoxy resin, there can be mentioned a two-component epoxy resin of "Cemedyne" (trade name, produced by Cemedyne Co.). Further, as the thermosetting liquid epoxy resin, there can be mentioned a one component epoxy resin of "Technodyne" (trade name, produced by Taoka Kagaku Co.), a liquid epoxy resin "Epicoat" (trade name, produced by Yuka Shell Epoxy Co.), a latent curing agent "Novacure" (trade name, produced by Asahi Kasei Industry Co.) and "Amicure" (trade name, produced by Ajinomoto Co.). As the thermosetting powdery epoxy resin, there can be mentioned "Epiform" (trade name, manufactured by Somal Co.), and the powdery epoxy resin may also be used as a flow controlling agent for the liquid epoxy resin. The blending amount of the thermosetting synthetic resin is from 25 to 50% by weight, preferably 25 to 43% by weight. If the blending amount of the thermosetting synthetic resin is less than 25% by weight, the binding effect of the binder would not be sufficiently exhibited, thereby drawing out of from the apertures or the grooves in the metal substrate when sliding member is produced. Further, if the blending amount exceeds 50% by weight, although bonding strength of the solid lubricant to a metal substrate or mechanical strength of the solid lubricant is enhanced, the lubricating properties of the solid lubricant tends to be impaired. The lubricating composition in the present invention can be prepared as shown below. A carrier absorbing and possessing the lubricating oil is blended and mixed with a solid lubricant powder material and a thermoplastic synthetic resin, and then the lubricating oil is blended and mixed with the thus-obtained mixture. Then, a thermosetting synthetic resin binder is added to the resultant mixture of the solid lubricant powder material, the carrier, the lubricating oil and the thermoplastic synthetic resin, and they are kneaded to obtain a lubricating composition having a wettability and a fluidity. In addition to liquid thermoplastic synthetic resin, a thermosetting synthetic resin powder may be added during kneading for controlling the fluidity of the lubricating composition. The thus obtained lubricating composition having a wettability and a fluidity is flow-charged at an ordinary temperature or under the heating (e.g., 20 to 40°C) under a pressure of 50 to 300 kgf/cm 2 into the apertures or the grooves disposed in the metal substrate, and subsequently, the thermosetting synthetic resin binder therein is cured at an ordinary temperature or under the heating (e.g., 80 to 160°C) to bond the lubricating composition containing the lubricating oil with the apertures or the grooves in the metal substrate, thereby obtaining a sliding member embedded with a solid lubricant containing the lubricating oil. As a method of flow-charging the lubricating composition having a wettability and a fluidity into the apertures or the grooves disposed in the metal substrate, transfer molding, compression molding, injection molding or the like may be used. In case of a plate-like sliding member, there can be used a method of previously molding the lubricating composition into a plate-like shape, placing the thus-obtained plate-like solid lubricant on a plate-like sliding part formed with apertures of grooves and then flow-charging the lubricating composition by press molding or roll molding. Fig. 1 is a cross sectional view illustrating one embodiment of a flow-charging device for the lubricating composition and Fig. 2 is a cross sectional view taken along line II-II in Fig. 1. In the drawing, there are illustrated a holder 1 having a cylindrical portion 11; a sliding member material (metal substrate) 2 fitted into the cylindrical portion 11 of the holder 1 with its outer circumferential surface to be constrained, and having apertures 21 formed such that they are overlapped to each other in the outer circumferential direction; a guide member 3 having a radial flow channel 31 formed at the upper end surface and inserted to the inner surface of the sliding member material 2 with a slight gap S relative to the inner diametrical surface of the material 2; a vessel 4 fitted to the upper end of the cylindrical portion 11 of the holder 1 which holds the material 2 and having a flow channel 41 in communication with the flow channel 31; a lubricating composition 5 having a wettability and a fluidity charged in the vessel 4; and a pressing tool 6 fitted vertically movably in the vessel 4. Fig. 3 is a cross sectional view illustrating a solid lubricant-embedding sliding member manufactured by using the apparatus as described above, in which are shown a sliding member 7, apertures 71 formed in the sliding member material and solid lubricant 72 embedded in the apertures 71. The bonding strength between the solid lubricant and the metal substrate in the sliding member having the solid lubricant embedded therein according to the present invention is not less than 50 kgf/cm 2 . At a 200 mm stroke of a reciprocating sliding test and after 100 x 10 4 of test cycles (400 Km test stroke), by using the mechanical structural carbon steel (S45C) as the mating member, (1) a friction coefficient is not more than 0.135, preferably not more than 0.115 and the abrasion amount is not more than 0.0125 mm, preferably not more than 0.012 mm under a load of 500 kgf/cm 2 and at a sliding speed at 1 m/min; and (2) a friction coefficient is not more than 0.125, preferably not more than 0.105 and abrasion amount is not more than 0.0105 mm, preferably not more than 0.0085 mm under a load at 10 kgf/cm 2 and at a sliding speed at 40 m/min. The solid lubricant and the sliding member according to the present invention have effects as described below. (1) Since the lubricating composition has a wettability and a fluidity, it can be embedded without restriction at all of the shape of the apertures or grooves disposed in the metal substrate. (2) Since the solid lubricant obtained from the lubricating composition contains in itself a lubricating oil, the lubricating oil possessed by the carrier in the solid lubricant is supplied to the sliding surface during sliding movement relative to the mating member in the solid lubricant-embedding sliding member, the wettability by the lubricating oil can be possessed, by which lubricating effect of the solid lubricant and the lubricating oil can be conducted. Accordingly, it is no more necessary to supply additional lubricant such as grease to the sliding surface as in the prior art for the solid lubricant-embedding sliding member under a low speed and high load condition, as well as for the application use out of such conditions, and the use under wide range of conditions is enabled. (3) Since the lubricating oil is absorbed and possessed in the carrier, the bleeding out thereof is extremely small and a great amount of the lubricating oil is contained in the solid lubricant. (4) Since the lubricating composition is embedded by flow charging into the apertures or the grooves disposed in the metal substrate, conventional adhesive coating operation or embedding operation in the prior art is no more necessary to remarkably improve the operability, as well as troubles such as skin eruption of operators caused by the adhesive coating operation can be overcome thoroughly. <Examples> The lubricating composition and the sliding member having the solid lubricant embedded therein according to the present invention will be explained more in details referring to examples. Example I As a solid lubricant powder material, 16% by weight of polytetrafluoroethylene powder (PTFE) and 13% by weight of boron nitride were used; 11% by weight of an aromatic polyamide ("Cornex" (trade name), manufactured by Teijin Corporation) as a thermoplastic synthetic resin and 4% by weight of a hydrocarbon wax ("Godeswax" (trade name), manufactured by Nikko Fine Products Co.) as a carrier were added with the above-mentioned solid lubricant powder material by a mixer; and 13% by weight of a mineral oil as a lubricating oil ("Daffny Super Multi" (trade name), manufactured by Idemitsu Kosan Co.) were mixed with the resultant mixture to obtain a mixture of PTFE, boron nitride, the aromatic polyamide, the hydrocarbon wax and the mineral oil. Then, 26% by weight of a thermosetting liquid epoxy resin ("Epicoat" (trade name), manufactured by Showa Shell Chemical Co.) as a thermosetting synthetic resin binder, 7% by weight of a latent-type setting agent ("Novacure" (trade name), manufactured by Asahi Kasei Industry Co.) and 10% by weight of a powdery epoxy resin ("Epiform" (trade name), manufactured by Somal Co.) for flow control were mixed with the thus-obtained mixture and then kneaded to obtain a lubricating composition having a wettability and a fluidity. The lubricating composition had white colour. A high strength brass casting product (JIS-H2205) was used as a metal substrate, which was fabricated by cutting into a cylindrical substrate of 60 mm in inner diameter, 80 mm in outer diameter and 80 mm in length, and 54 apertures each of 10 mm in diameter were formed to the cylindrical substrate so as to overlap to each other in the circumferential direction of the cylindrical substrate to form a sliding member material. While constraining the sliding member material at the outer circumferential surface, the lubricating composition was caused to flow at an ordinary temperature under a pressure of 150 kg/cm 2 from the inner circumferential surface of the material by the flow discharging device shown in Fig. 1 and was tightly charged into the apertures of the material. Subsequently, the sliding member material having the lubricating composition held in the apertures was kept in a heating furnace to a temperature of 80°C for 60 min to conduct primary setting for the thermosetting synthetic resin binder and then further kept in the heating furnace to a temperature of 140°C for 30 min to conduct the secondary setting for the thermosetting synthetic resin binder. At the same time, the lubricating composition containing the lubricating oil was bonded to the apertures of the material, thereby obtaining the sliding member having the solid lubricant embedded therein (bearing bush). The obtained sliding member was one in which 54 pieces of the white solid lubricants were charged and bonded to a high strength brass material having gold colour. Example II As a solid lubricant powder material, 16% by weight of PTFE and 13% by weight of boron nitride were used; 11% by weight of an aliphatic polyamide (nylon 12) as a thermoplastic synthetic resin and 4% by weight of a hydrocarbon wax (same as in Example I) as a carrier were added with the solid lubricant powder material by a mixer; and 13% weight of a mineral oil as a lubricating oil (same as in Example I) were mixed with the resultant mixture to obtain a mixture of PTFE, boron nitride, the polyamide, the hydrocarbon wax and the mineral oil. Then, 26% by weight of a thermosetting liquid epoxy resin (same as in Example I) as a thermosetting synthetic resin binder, 7% by weight of a latent type curing or setting agent (same as in Example I) and 10% by weight of a powdery epoxy resin (same as in Example I) for flow control were mixed with the thus-obtained mixture and then kneaded to obtain a lubricating composition having a wettability and a fluidity. The lubricating composition had white colour. The same high strength brass casting product as in Example I was used as a metal substrate, it was fabricated into a cylindrical substrate having the same dimension and 54 apertures were formed so as to overlap to each other in the circumferential direction of the cylindrical substrate to form a sliding member material. Subsequently, the solid lubricant-embedding sliding member (bearing bush) was obtained in the procedures as those in Example I. The obtained sliding member was one in which 54 pieces of the white solid lubricants were charged and bonded to a high strength brass material having gold colour. Example III As a solid lubricant powder material, 16% by weight of PTFE and 13% by weight of boron nitride were used; 11% by weight of aromatic polyamide fibers (diameter: 15 µm, length: not more than 3 mm, "Cornex" (trade name), manufactured by Teijin Corporation) as a thermoplastic synthetic resin and 4% by weight of a hydrocarbon wax (same as in Example I) as a carrier were added with the solid lubricant powder material by a mixer; and 13% weight of a mineral oil as a lubricating oil (same as in Example I) were mixed with the resultant mixture to obtain a mixture of PTFE, boron nitride, the aromatic polyamide fiber, the hydrocarbon wax and the mineral oil. Then, 25% by weight of a thermosetting liquid epoxy resin (same as in Example I) as the thermosetting synthetic resin binder, 8% by weight of a latent type setting agent (same as in Example I) and 10% by weight of a powdery epoxy resin (same as in Example I) for flow control were mixed with the thus-obtained mixture and then kneaded to obtain a solid lubricant having a wettability and a fluidity. The lubricating composition had white colour. The same high strength brass casting product as in Example I was used as a metal substrate, it was fabricated into a cylindrical substrate having the same dimension and 54 apertures were formed so as to overlap to each other in the circumferential direction of the cylindrical substrate to form a sliding member material. Subsequently, the solid lubricant-embedding sliding member (bearing bush) was obtained in the procedures as those in Example I. The obtained sliding member was one in which 54 pieces of the white solid lubricants were charged and bonded to a high strength brass material having gold colour. Example IV As a solid lubricant powder material, 16% by weight of fluorinated graphite and 18% by weight of PTFE were used; 13% by weight of a polyether ether ketone powder ("Victolex" (trade name), manufactured by ICI Japan Co.) as a thermoplastic synthetic resin and 4% by weight of stearic acid as a carrier were added with the solid lubricant powder material by a mixer; and 13% by weight of a mineral oil as a lubricating oil (same as in Example I) were mixed with the resultant mixture to obtain a mixture of fluorinated graphite, PTFE, polyether ether ketone, stearic acid and the mineral oil. Then, 30% by weight of a thermosetting liquid epoxy resin ("Technodyne AH604W" (trade name), manufactured by Taoka Kagaku Co.) as the thermosetting synthetic resin binder and 6% by weight of a powdery epoxy resin (same as in Example I) were mixed with the thus-obtained mixture and then kneaded to obtain a solid lubricant having a wettability and a fluidity. The lubricating composition had white colour. The same high strength brass casting product as in Example I was used as a metal substrate, it was fabricated into a cylindrical substrate having the same dimension and 54 apertures were formed so as to overlap to each other in the circumferential direction of the cylindrical substrate to form a sliding member material. Subsequently, the solid lubricant-embedding sliding member (bearing bush) was obtained in the procedures as those in Example I. The obtained sliding member was one in which 54 pieces of the white solid lubricants were charged and bonded to a high strength brass material having gold colour. Example V As a solid lubricant powder material, 44% by weight of a soft metal (lead) powder and 16% by weight of PTFE were used; 10% by weight of a polyether ether ketone powder (same as Example IV) as a thermoplastic synthetic resin and 2% by weight of stearic acid as a carrier were added with the solid lubricant powder material by a mixer; and 8% by weight of a mineral oil as a lubricating oil (same as in Example I) were mixed with the resultant mixture to obtain a mixture of lead, PTFE, the polyether ether ketone, stearic acid and the mineral oil. Then, 17% by weight of a thermosetting liquid epoxy resin ("Technodyne AH604W" (trade name), manufactured by Taoka Kagaku Co.) as the thermosetting synthetic resin binder and 3% by weight of a powdery epoxy resin (same as in Example I) were mixed with the thus-obtained mixture and then kneaded to obtain a solid lubricant having a wettability and a fluidity. The lubricating composition had gray colour. The same high strength brass casting product as in Example I was used as a metal substrate, it was fabricated into a cylindrical substrate having the same dimension and 54 apertures were formed so as to overlap to each other in the circumferential direction of the cylindrical substrate to form a sliding member material. Subsequently, the solid lubricant-embedding sliding member (bearing bush) was obtained in the procedures as those in Example I. The obtained sliding member was one in which 54 pieces of the gray solid lubricants were charged and bonded to a high strength brass material having gold colour. Then, the results of tests for the bonding strength of the solid lubricant and the sliding characteristics of the sliding member regarding the solid lubricant and the sliding member composed of the solid lubricant obtained in the examples described above were set forth below. (Bonding Strength Test) For the bonding strength, a push-pull gauge was placed on the solid lubricant embedded into the apertures of the sliding member to measure the drawing-out force (kgf/cm 2 ) of the solid lubricant from the apertures and the bonding strength was expressed by the measured value. (Sliding Property Test) For the sliding property, a friction coefficient and an abrasion amount were measured under the following test conditions. (Test Conditions for the sliding member of Examples I to V) (1) Load: 500 kgf/cm 2 Speed: 1 m/min Mating member: Carbon steel for machine structure use (S45C) Reciprocating Sliding test: Stroke 200 mm Test cycle: 100 x 10 4 (400 km) Lubrication: No lubrication (2) Load: 10 kgf/cm 2 Speed: 40 m/min Mating member: Carbon steel for machine structure use (S45C) Reciprocating Sliding test: Stroke 200 mm Test cycle: 100 x 10 4 (400 km) Lubrication: No lubrication The test results are shown in the following table. The sliding properties of the sliding members of Examples I to V in the low speed/high load region (under test conditions (1) above) in the appropriate application use for the solid lubricant-embedding sliding member, as well as in other application uses out of the low speed/high load region (under test conditions (2) above) were superior to those of the Comparative Example. In each of the sliding members of Examples I to V, the bonding strength between the lubricating composition and the aperture of the substrate was not less than 50 kgf/cm 2 . Although the bonding strength of the solid lubricant of the Examples to the apertures in the sliding member (drawing-out force) showed lower values than those in Comparative example I, the solid lubricant in the Examples caused no troubles at all in using the sliding members, as seen from the results of the above sliding property test. In the solid lubricant-embedded sliding member of Comparative Example I(1) in which graphite pellets were bonded to apertures with adhesives, the friction coefficient was gradually increased with lapse of test time in the test under the test condition (1) and the abrasion amount was abruptly increased at 300 km test stroke. Further, since the bearing temperature, friction coefficient and abrasion amount were increased abruptly at 1 km of the test stroke after the start of the test under the test conditions (2) above, the test was interrupted. The abrasion amount shown in Table 2 was a measured value at 300 km the test stroke. The sliding member of Comparative Example I(2), in which graphite pellets were bonded to apertures with adhesives and grease was coated on the sliding surface, showed substantially the same performance as the sliding member of Example I through Example V in the test under the test conditions (1), but grease coated on the sliding surface began to be squeezed out to the sliding surface at the test stroke of 200 km and both of the friction coefficient and the abrasion amount increased abruptly at the test stroke of 300 km in the test under the test conditions (2) and, accordingly, subsequent test was interrupted. The abrasion amount shown in Table 2 was a measured value at 300 km the test stroke. On the other hand, since the lubricating oil is contained in the solid lubricant of the Examples, it exhibited stable performance without additionally supplying a lubricant not only in the low speed/high load region (the test condition (1)) as the appropriate application use for the solid lubricant-embedding sliding member but also in other application uses out of the such region (the test condition (2)).

Claims: A lubricating composition comprising 5 to 65% by weight of a solid lubricant material, 5 to 20% by weight of a lubricating oil which is in a liquid or paste form at ordinary temperature, 1 to 8% by weight of a carrier for absorbing and possessing said lubricating oil, 10 to 30% by weight of a thermoplastic synthetic resin other than polytetrafluoro ethylene (PTFE) and 25 to 50% by weight of a thermosetting synthetic resin. A lubricating composition according to claim 1, wherein the carrier is at least one selected from the group consisting of hydrocarbon waxes, higher fatty acids, waxes of derivatives of higher fatty acids, oleophilic fibers, crosslinked porous spherical particles composed of styrene or methacrylic compound, porous calcium carbonate, phenol carbide resin, and rubber oil-absorbing materials. A lubricating composition according to claim 1, wherein the thermoplastic synthetic resin is selected from the group consisting of aliphatic polyamide, aromatic polyamide, polyacetal, polyether ether ketone, polyphenylene sulfide, polybutyrene terephthalate and oxybenzoyl polyester. A lubricating composition according to claim 1, wherein the thermosetting synthetic resin is selected from the group consisting of epoxy resin, modified epoxy resin, phenol resin, phenoxy resin and alkyd resin. A sliding member comprising a solid lubricant embedded into apertures or grooves of a metal substrate, said solid lubricant being obtained by flow-charging said lubricating composition defined in claim 1 into the apertures or grooves of the metal substrate and bonding the charged lubricating composition to said apertures or grooves of said metal substrate. A sliding member according to claim 5, wherein the sliding surface of the metal substrate formed with the apertures or grooves is a flat, cylindrical or spherical surface.

Inventors: CHOU HIDEO, SUMIYOSHI KIKUO, CHOU, HIDEO, SUMIYOSHI, KIKUO
Applicants: OILES INDUSTRY CO LTD, OILES CORPORATION
Application year: 1992
Main classification: C10M111
IPC codes: C10N40, C10N30, C10N80, C10M111, C10N50