JP2019065924A - Conductive slide bearing - Google Patents

Abstract

To provide a highly conductive slide bearing capable of improving electric conduction with a target material in a state of maintaining slidability.SOLUTION: A conductive slide bearing 1 is composed of a resin molding of a conductive resin composition, and has a slide surface 4, wherein the slide surface slides with a target material 3 rotating in an arrow A direction. On a surface other than the slide surface 4 of the conductive slide bearing 1, a flocked part 2 with fibers transplanted therein is provided so that the fibers transplanted in the flocked part 2 contact with the targeting material 3, but the flocked part 2 does not directly contact with the targeting material 3.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a conductive sliding bearing in which a sliding surface sliding with a mating material is formed of a conductive resin composition.

  2. Description of the Related Art An image forming apparatus such as an electrophotographic copying machine, a printer, and a facsimile is required to be compact, lightweight, easy to use, and low in cost. At the same time, also in the developing devices incorporated in these devices, for example, the development of easy-to-use, compact and lightweight removable process cartridges has progressed. Oil-impregnated sintered sliding bearings and resin-made sliding bearings are widely used instead of rolling bearings as bearings at sliding parts of such a developing device. Among them, resin-made slide bearings are widely used, in which the change in sliding characteristics with respect to temperature change is small compared to oil-impregnated sintered slide bearings.

  A sliding bearing using an oil-impregnated resin sliding material as a resin sliding bearing is superior in low friction to a sliding bearing consisting of a sliding material containing an oil-impregnated resin or solid lubricant without using a conventional oil-retaining body. However, it is difficult to impart conductivity simply by blending a conductive material. That is, when the compounded conductive material is concealed by a lubricating component such as oil and it is difficult to exhibit conductive performance, or the lubricating component is held at the conductive material / resin interface and the lubricating component necessary for sliding is a sliding interface. In some cases, the wear resistance and the friction torque may be significantly deteriorated and the service life may be shortened. When a shaft made of a soft material such as aluminum is used as a sliding counterpart material, the above-mentioned oil shortage or the blended conductive material may damage the counterpart material.

  In order to cope with such problems, it has both excellent low friction and low abrasion properties that make it possible to continuously supply a lubricant to the sliding part surface, and conductivity more than that required for antistatic prevention. An electroconductive sliding bearing that can be used and does not damage the soft mating material is known (see Patent Document 1).

  In addition, in order to improve the lubricating characteristics including the reduction of the rotational torque of the rolling bearing, a rolling bearing in which a flocked portion formed by flocking fibers is formed on the surface that contacts the lubricant other than the contact surface with the rolling element. An example is disclosed that uses a conductive fiber in the flocked part (see Patent Document 2).

JP, 2008-164073, A International Publication No. 2015/141822

  However, conductive sliding bearings used for photosensitive drums and the like are formed of a resin compounded with a conductive resin composition, and usually have a cylindrical shape, and the mating material rotates and slides, so the contact area due to the difference between inner and outer diameters May be small and the current may not be stable.

  In general, when forming a flocked portion for the purpose of improving the retention of grease, depending on the shape, position, and conditions of use, it may have an adverse effect such as an increase in sliding resistance, which is a sufficient effect. May not be obtained.

  The present invention has been made to address such problems, and it is an object of the present invention to provide a highly conductive sliding bearing capable of improving the conductivity with a mating material.

  The conductive sliding bearing according to the present invention is made of a resin molded body of a conductive resin composition, has a sliding surface that slides with a mating material, and a fiber other than the above-mentioned sliding surface of the conductive sliding bearing. Is characterized in that at least a part of the flocked part is in contact with the opposite material.

  The flocking portion is provided on a surface of the conductive slide bearing not in direct contact with the mating member. Furthermore, the conductive sliding bearing is cylindrical, and the surface on which the flocked portion is provided is at least one surface selected from the inner peripheral surface and the end surface of the bearing.

It is characterized in that the flocked fibers are conductive fibers.
Further, the fiber is characterized in that the fiber is in the shape of being fallen in the rotation direction of the mating material from the upright state with respect to the surface on which the flocked portion is provided.

  The conductive sliding bearing according to the present invention is a flocked fleece in which fibers are flocked on a surface other than the sliding surface of the conductive sliding bearing and which is not in direct contact with the mating material (inner peripheral surface or end surface of cylindrical bearing) Since it has a part, it does not affect the slidability with the mating material. Further, since the implanted fibers come in contact with the mating material, the conductivity with the mating material is improved. In particular, when the fiber itself is made conductive or when the fiber is made to hold a conductive grease, the conductivity can be further improved.

It is a figure which shows an example of the electroconductive sliding bearing of this invention.

  The conductive sliding bearing of the present invention will be described based on FIG. Fig.1 (a) is the figure which looked at the bearing structure which included the other material, FIG.1 (b) is sectional drawing of an electroconductive sliding bearing. The slide bearing device shown in FIG. 1 comprises a cylindrical conductive slide bearing 1, a mating member 3 sliding in the direction of arrow A in the bearing, and fibers flocked so as to be able to contact the mating member. It comprises the flocking part 2. The hair-implanted portion 2 can improve the conductivity of the conductive sliding bearing 1 and the mating member 3.

  The flocking portion 2 provided in the conductive sliding bearing 1 is formed at a location other than the sliding surface 4 between the mating member 3 and the conductive sliding bearing 1. Examples of such a flocked portion 2 include a flocked portion 2a provided on the inner circumferential surface of the bearing and a flocked portion 2b provided on the end face of the bearing. These flocked parts 2a and 2b may be provided alone or both at the same time. Because the clearance between the facing 5 of the sliding surface 4 and the surface of the mating member 3 is small, it is preferable that the flocked portion 2 be a flocked portion 2 b provided on the end face of the bearing.

  Here, the bearing inner peripheral surface in which the flocking part 2a is provided is demonstrated. The diameter of the rotating shaft which is the mating member 3 supported by the conductive sliding bearing 1 is slightly smaller than the diameter of the bearing body. In the rotary bearing portion of the image forming apparatus, a radial load is loaded perpendicularly to the axis of the rotary shaft, so the inner top portion side of the cylindrical section (the sliding surface 4 to which the load is loaded) in the cylindrical bearing At the opposite side of the bottom side, there is space due to the difference in diameter between the bearing body and the rotating shaft. The flocked portion 2a is formed on the bearing inner peripheral surface (facing 5) on the inner top portion side, which is a surface on which the bearing does not directly contact the mating member.

  In the conductive sliding bearing of the present invention, the sliding surface sliding with the mating material is a molded body of the conductive resin composition. The conductive resin composition is preferably a resin composition in which a conductive material and a lubricity imparting material are blended in a synthetic resin.

  The synthetic resin is not particularly limited as long as it is a synthetic resin such as a thermoplastic resin, a thermosetting resin, or the like that can be used as a sliding material of a slide bearing. For example, polyethylene resin such as low density polyethylene, high density polyethylene, ultra high molecular weight polyethylene, modified polyethylene resin, water cross-linked polyolefin resin, polyamide resin, aromatic polyamide resin, polystyrene resin, polypropylene resin, silicone resin, urethane resin, PTFE resin Chlorotrifluoroethylene resin, tetrafluoroethylene / hexafluoropropylene copolymer resin, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer resin, vinylidene fluoride resin, ethylene / tetrafluoroethylene copolymer resin, polyacetal resin, Polyethylene terephthalate resin, polybutylene terephthalate resin, polyphenylene ether resin, polycarbonate resin, aliphatic polyketone resin, polyvinyl pyro Don resin, polyoxazoline resin, polyphenylene sulfide resin, polyether sulfone resin, polyether imide resin, polyamide imide resin, polyether ether ketone resin, thermoplastic polyimide resin, thermosetting polyimide resin, epoxy resin, phenol resin, not A saturated polyester resin, a vinyl ester resin, etc. can be illustrated. Moreover, the mixture of 2 or more types of materials selected from the said synthetic resin, ie, a polymer alloy, etc. can be illustrated.

  Examples of the conductive material include metals and carbon-based materials. In particular, it is preferable to use a carbon-based material that easily forms a microfibrous material. Examples of carbon-based materials include carbon fibers. The carbon fiber is preferably carbon fiber having a fiber diameter of 0.3 μm or less, a fiber length of 1 μm or more, and an aspect ratio of 5 or more.

  The blend ratio of the conductive material in the conductive resin composition is 0.1% by volume or more and less than 5% by volume, preferably 0.5% by volume to 3% by volume. If it is less than 0.1% by volume, sufficient conductivity can not be imparted. If the content is 5% by volume or more, the abrasion resistance is particularly deteriorated, and damage to the mating material may occur, which is not preferable.

  It is preferable to use a lubricant obtained by impregnating a porous body with a lubricant. By using the porous body impregnated with the lubricant, since the lubricant can be continuously supplied to the sliding interface, excellent friction and wear characteristics can be maintained. Moreover, the oil content in a composition can be increased by mix | blending the porous body in which the lubricating agent was impregnated.

  The compounding ratio of the lubricity imparting material in the conductive resin composition is 5% by volume or more and less than 60% by volume, and more preferably 30% by volume to 50% by volume. If it is less than 5% by volume, sufficient lubricity can not be provided, and the coefficient of friction can not be reduced. If it is 60% by volume or more, the amount of the base resin becomes too small, and the formability deteriorates. In addition, the strength and the abrasion resistance may decrease, which is not preferable. In addition, the compounding quantity of the lubricant to occupy in a lubricity imparting material is 90 volume%-150 volume% of the internal space volume of a porous body. The lubricant is not particularly limited as long as it is a substance having a lubricating effect, such as a lubricating oil which is liquid at normal temperature, a wax which is solid at normal temperature, or a grease-like substance containing a thickener in the lubricating oil.

  An appropriate filler can be added to the conductive resin composition in order to further improve friction and wear characteristics and improve various mechanical properties. For example, fibers such as glass fibers, aramid fibers, alumina fibers, boron fibers, silicon carbide fibers, silicon nitride fibers, BN fibers, quartz wool, metal fibers or those knitted into a cloth, calcium carbonate, lithium phosphate Minerals such as lithium carbonate, calcium sulfate, lithium sulfate, talc, silica, clay, mica, etc., inorganic oxide whiskers such as titanium oxide whisker, potassium titanate whisker, aluminum borate whisker, calcium sulfate whisker, carbon black, graphite, Various thermosetting resins such as polyester fiber, polyimide resin and polybenzimidazole resin can be mentioned.

Further, for the purpose of improving the slidability, amino acid compounds, polyoxybenzoyl polyester resin, polybenzimidazole resin, liquid crystal resin, pulp of aramid resin, PTFE resin, BN, MoS ₂ , tungsten disulfide and the like can be blended.

  In addition, metal fibers, zinc oxide, etc. may be blended for the purpose of improving the thermal conductivity. Of course, it is also possible to use two or more of the above-mentioned fillers in combination. In addition, you may use together the additive which can be widely applied to general synthetic resin by the compounding quantity which does not inhibit the outstanding electroconductivity and lubricity. For example, industrial lubricants such as mold release agents, flame retardants, weatherability improvers, and colorants may be added as appropriate, and the method of adding these is not particularly limited.

  The method of molding the conductive resin composition can be appropriately selected according to the type of material and the shape of the molded article, such as compression molding, injection molding, extrusion molding, blow molding, vacuum molding, transfer molding and the like. Among these, injection molding is preferred, which facilitates uniform filling of the conductive material and the lubricity imparting material.

  The flocking portion 2 can be formed by flocking a short fiber on the surface of the conductive slide bearing 1, for example. Spraying or electrostatic flocking can be employed as the flocking coating method. It is preferable to adopt electrostatic flocking because a large amount of fibers can be densely and vertically flocked in any place on the surface of the conductive sliding bearing 1 in a short time. A publicly known method can be adopted as the electrostatic flocking method. For example, as an electrostatic flocking method, (1) a step of applying an adhesive to a range to which the electrostatic flocking of the conductive sliding bearing 1 is applied, (2) spraying the short fiber charged to the conductive sliding bearing 1 by electrostatic force (3) drying the surface on which the short fibers are temporarily attached to sufficiently cure the adhesive to fix the short fibers to the surface of the conductive slide bearing 1 A method including a process and the like can be mentioned.

  Examples of the adhesive that can be used for electrostatic flocking include adhesives having as a main component urethane resin, epoxy resin, acrylic resin, vinyl acetate resin, polyimide resin, silicone resin and the like. For example, urethane resin solvent based adhesives, epoxy resin solvent based adhesives, vinyl acetate resin solvent based adhesives, acrylic resin based emulsion adhesives, acrylic acid ester-vinyl acetate copolymer based emulsion adhesives, vinyl acetate based emulsion adhesives And urethane resin emulsion adhesives, epoxy resin emulsion adhesives, polyester emulsion adhesives, ethylene-vinyl acetate copolymer adhesives, and the like. These may be used alone or in combination of two or more.

  The short fibers used for flocking are not particularly limited as long as they can be used as short fibers for flocking; for example, (1) polyolefin resins such as polyethylene and polypropylene, polyamide resins such as nylon, aromatic polyamide resins, polyethylene terephthalate Polyester resin such as polyethylene naphthalate, polyethylene succinate, polybutylene tephthalate, synthetic resin fiber such as acrylic resin, vinyl chloride, vinylon, (2) Carbon fiber, inorganic fiber such as glass fiber, (3) rayon, acetate etc And natural fibers such as cotton, silk, hemp, wool and the like. These may be used alone or in combination of two or more. Among the above, it is preferable to use a synthetic resin fiber because it is less likely to cause swelling or dissolution by oil, is chemically stable, can produce a large amount of homogeneous fibers, and can be obtained inexpensively. Moreover, when setting it as the electroconductive flocking part 2, it is preferable to use the electroconductive short fiber which compounded electroconductive fillers, such as carbon black, with polyethylene resin as a fiber used for a flocking part.

  In particular, in the case of improving conductivity, as the short fibers used for flocking, short fibers of metals having excellent conductivity or alloys containing these metals can be used. Preferred metal fibers include a single substance of at least one metal selected from aluminum, gold, silver, copper and iron or an alloy containing these metals. These may be used alone or in combination of two or more.

  The shape of the short fiber is not particularly limited as long as it can be uniformly formed on the surface of the resin molded body. As a specific shape, for example, one having a length of 0.5 to 2.0 mm and a thickness of 0.5 to 50 dtex is preferable, and as the density of short fibers, the ratio of fibers occupied per flocked area is 10 -40% is preferable. There are straight and bend (a shape in which the tip is bent) as the shape of the short fiber, and the cross-sectional shape is circular or polygonal. By using the short fibers of the polygonal cross section, the surface area can be made larger than the short fibers of the circular cross section, and the conductivity can be improved.

  Moreover, it is preferable to make the fiber in a flocking part into the shape which fell in the rotation direction of the other material from the upright state with respect to the surface in which this flocking part is provided. This shape can be formed by heat treating the fibers after flocking. In particular, as shown in the embodiment of FIG. 1, it is preferable to make the shape of the fibers in the flocked portion 2 b in contact with the rotation shaft into a shape that falls in the rotation direction of the mating member 3. Similarly, when the flocked portion 2a is in light contact with the rotation shaft, it is preferable that the fibers in the flocked portion 2a have a shape in which the fibers in the flocked portion 2a fall in the rotational direction of the mating member 3. The resistance caused by the contact between the flocking portion and the opposing member is further reduced, and the adverse effect (such as an increase in torque) on the slidability can be suppressed.

  In the case of applying a lubricant such as grease or lubricating oil to the inner surface of the slide bearing, it is preferable to use a conductive grease. In the conductive grease, for example, a carbon-based thickener is used in place of a conventional thickener. Examples of carbon-based thickeners include carbon black, graphite, fullerenes, carbon nanotubes, carbon nanofibers, carbon fibers and the like. Among these, carbon black is preferable because it is easy to obtain stable electrical conductivity. As carbon black, furnace black, channel black, acetylene black, ketjen black etc. can be used. When a conductive grease is used, a conventional thickener may be used, and a conductive additive such as a carbon based compound may be blended as an additive. By using the conductive grease, even when the fibers of the flocked portion do not have conductivity, the conductive grease is held in the flocked portion, and the conductivity with the opposite material is improved through this.

  The conductive sliding bearing according to the present invention can reduce the axial torque for driving and rotating, and reduce the static electricity generated with the driving rotation, and escape from the developing device of the image forming apparatus without charging the generated static electricity. be able to. Therefore, a compact drive device can be used, and the development device can be reduced in size and weight. As a result, for example, it is suitable for a bearing portion in a process cartridge in which an electrostatic latent image forming unit, a developer supplying unit, a developing unit, an antistatic unit, an electrostatic removing unit and the like are formed into a cartridge. Further, the present invention can be applied to bearings in copying machines, laser beam printers, ink jet printers and the like.

  The conductive sliding bearing of the present invention is excellent in conductivity while maintaining the slidability, and therefore, can be used as a bearing portion in an image forming apparatus.

1 Conductive sliding bearing 2 Flocked portion 3 Counterpart material 4 Sliding surface 5 Face to face

Claims (5)

A conductive sliding bearing comprising a resin molded body of a conductive resin composition and having a sliding surface that slides on a mating material,
In a surface other than the sliding surface of the conductive sliding bearing, there is a flocked portion on which fibers are flocked,
An electroconductive sliding bearing characterized in that at least a part of the flocking portion contacts the mating member.   The conductive sliding bearing according to claim 1, wherein the flocking portion is provided on a surface of the conductive sliding bearing not in direct contact with the mating member. The conductive sliding bearing is cylindrical,
The conductive sliding bearing according to claim 1 or 2, wherein the surface on which the flocked portion is provided is at least one surface selected from an inner peripheral surface and an end surface of the bearing.   The conductive plain bearing according to any one of claims 1 to 3, wherein the fiber is a conductive fiber.   5. The fiber according to any one of claims 1 to 4, characterized in that the fiber is in the shape of being fallen in the direction of rotation of the mating material from the upright state with respect to the surface on which the flocked portion is provided. Electrically conductive sliding bearing as described.

Images