JP2015148285A - slide bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a slide bearing capable of suppressing its price while maintaining a bearing characteristic over a long period.SOLUTION: A slide bearing 1 includes a bearing outer peripheral part 2 comprising a metal base material, and a resin layer 3 molded integrally to a surface to be the slide surface of the bearing outer peripheral part by injection molding with a resin material. The resin material mainly comprises a polyethylene resin A enabling injection molding, and contains a non-injection molding fluorine resin B. In the resin material, the mass of the fluorine resin B has over 10 mass% and 40 mass% or less based on the total mass of the PE resin A and the fluorine resin B.

Description

  The present invention relates to a sliding bearing, and more particularly to a sliding bearing in which a resin layer mainly composed of polyethylene resin is formed by injection molding on a sliding surface of a metal substrate.

  In recent years, various studies have been made on bearings. For example, a plurality of rolling elements are held between inner and outer rings via a cage, and a lubricant film with a film thickness of 0.03 to 20 μm on the raceway surfaces of the inner and outer rings and the surface of the rolling elements. In which a lubricating oil compatible with the base oil constituting the lubricant film is contained in an amount of 10% by weight or more of the total weight, and a consistency No. defined in JIS K2220. Lubricating oil holders having a consistency greater than 3 occupy 1 to 10% of the bearing space by volume, and are arranged at appropriate positions in the cage so as not to contact the inner and outer raceway surfaces and the rolling element surface. A rolling bearing has been proposed (see Patent Document 1).

Japanese Patent Laid-Open No. 08-303467

  In the rolling bearing of Patent Document 1, a step of forming a lubricant film with a film thickness of 0.03 to 20 μm on the raceway surfaces of the inner and outer rings and the surface of the rolling element is required during the manufacturing process. In addition to this step, the lubricating oil holder is disposed at a proper position of the cage so as to occupy 1 to 10% of the bearing space by volume and not to contact the raceway surface of the inner and outer rings and the surface of the rolling element. A process is required.

  When trying to manufacture such a rolling bearing, complicated processes are increased in the manufacturing process of the rolling bearing, and productivity is reduced due to management of the complicated processes. As a result, the price of the rolling bearing is reduced. It is inferred that it will be difficult to suppress. Moreover, even if a complicated process is added, the effect of greatly extending the service life cannot be expected, and there is a concern that the quality may be excessive depending on the use part of the rolling bearing.

  In addition, the market demands further reduction in the price of rolling bearings, and in order to meet this demand, a sliding bearing having a significantly reduced number of parts is being demanded. Here, when a slide bearing is used as an alternative to a rolling bearing, the substitutable range largely depends on the PV value (multiplied by the surface pressure (P) and the sliding speed (V)) that the slide bearing can handle, 5 MPa · m / min. About 20%, 15 MPa · m / min. This will allow about 85% substitution. For this reason, a sliding bearing alternative to a rolling bearing is also required to have stable bearing characteristics such as being able to cope with a high PV value while maintaining a low coefficient of friction over a long period of time.

  The present invention has been made to cope with such problems, and an object of the present invention is to provide a plain bearing capable of keeping the price low while maintaining the bearing characteristics over a long period of time.

  The sliding bearing of the present invention is a sliding bearing having a metal base material and a resin layer integrally formed by injection molding using a resin material on a surface which becomes a sliding surface of the base material. The material is a material mainly composed of injection-moldable polyethylene (hereinafter referred to as “PE”) resin (A) and containing non-injectable fluororesin (B). In the resin material, the fluororesin (B) is more than 10% by mass and 40% by mass or less with respect to the total mass of the PE resin (A) and the fluororesin (B).

  The fluororesin (B) is a recycled polytetrafluoroethylene (hereinafter referred to as “PTFE”) resin. Moreover, the said fluororesin (B) was mix | blended with the said resin material by the powder form with an average particle diameter of 5-50 micrometers. The average particle diameter is a value measured by a laser diffraction method.

  The PE resin (A) is characterized in that the MFR is 1 to 30 g / 10 min when measured at a load of 10 kg and 190 ° C. based on JIS K 7210.

  The sliding bearing has a PV value obtained by multiplying the surface pressure (P) and the sliding speed (V) by 5 MPa · m / min. It is a bearing that is used under conditions that exceed the above.

  The plain bearing of the present invention has a metal base material and a resin layer integrally formed by injection molding using a resin material on a surface which becomes a sliding surface of the base material. It is a material mainly composed of a moldable PE resin (A) and containing a non-injection-moldable fluororesin (B). In the resin material, the fluororesin (B) is composed of PE resin (A) and fluororesin (B ) And exceeding 40% by mass with respect to the total mass, the low friction coefficient can be maintained over a long period of time even under high PV conditions, and the wear resistance is excellent. In addition, the resin layer can be insert injection molded, and a complicated manufacturing process is not required. Therefore, the resin layer is excellent in productivity, and the number of parts is smaller than that of a rolling bearing, so that the price can be kept low. As a result, the plain bearing of the present invention is expected as a substitute for the rolling bearing in many applications.

It is the perspective view and sectional drawing which show an example of the slide bearing of this invention. It is sectional drawing which shows the aspect of the structure of the resin layer formed in a bearing outer peripheral part. It is a figure which shows the relationship between PV value and a wear coefficient.

  The plain bearing of the present invention has a metal base material and a resin layer integrally molded (insert molding) by injection molding using a resin material on the surface which becomes the sliding surface of the base material. The resin material for forming this resin layer is a material mainly composed of injection-moldable PE resin (A) and a predetermined amount of non-injection-moldable fluororesin (B).

The PE resin (A) as the main component of the resin material may be any PE resin that can be injection molded. As injection molding conditions, for example, any injection molding conditions may be used as long as the molding temperature is 200 ° C. to 270 ° C. and the injection pressure is 100 to 160 MPa. In addition, high-density, high-molecular-weight PE resin with excellent properties such as wear resistance, self-lubrication, impact resistance, chemical resistance, lightness that is lighter than the specific gravity of water, and dimensional stability due to low water absorption. preferable. For example, a high density PE resin having a density (ASTM D 1505) of 942 kg / m ³ or more is preferable, and the upper limit of the density of the high density PE resin is less than 1000 kg / m ³ , strictly speaking, 980 kg / m ³ or less.

  The MFR (melt flow rate: JIS K 7210 (190 ° C., 10 kgf)) of the PE resin (A) is preferably 1 to 30 g / 10 minutes, more preferably 1 to 15 g / 10 minutes, and 2 to 6 g / 10 minutes. Is particularly preferred. As a weight average molecular weight, it is less than 1 million, Preferably it is about 250,000-950,000. Moreover, as a structure, a linear thing and the branched thing containing the branch of a methyl group may be sufficient. In addition, PE resin of (A) component may be used individually by 1 type, and 2 or more types may be mixed and used for it.

Commercially available products of PE resin (A) that can be used in the present invention include trade names Lübmer L3000 (density: 969 kg / m ³ , MFR: 15 g / 10 min) and L4000 (density: 967 kg / m ³ ) manufactured by Mitsui Chemicals. , MFR: 6 g / 10 min), L5000 (density: 966 kg / m ³ , MFR: 2 g / 10 min), and the like.

The fluororesin (B) blended in the resin material is a non-injection moldable fluororesin, and examples thereof include PTFE resin. PTFE resin is a crystalline thermoplastic resin, and its melting point is usually set to 327 ° C. for convenience, but the melt viscosity is extremely high at 10 ¹¹ poise even at 380 ° C., and the melt viscosity at the time of molding is 10 ³ to 10 Unlike a general thermoplastic resin having ⁴ poise, a melt molding method such as injection molding cannot be applied. For this reason, the PTFE resin mainly employs a molding method in which a powdery resin is preformed and heated to 360 to 390 ° C. above the melting point to sinter the particles. In the present invention, the fluororesin (B) is blended as a filler (powder) with respect to the PE resin (A) as a base, not the main component of the resin layer formed by injection molding. By containing the fluororesin (B), friction can be reduced, frictional heat generation can be reduced, and frictional wear characteristics are excellent even at high loads in a dry environment where no lubricating oil or grease is used on the sliding surface.

As the PTFE resin, a general PTFE resin represented by — (CF ₂ —CF ₂ ) _n — can be used, and a perfluoroalkyl ether group (—C _p F _2p —O) is _added to the general PTFE resin. Modified PTFE resin into which-) (p is an integer of 1-4) or a polyfluoroalkyl group (H (CF ₂ ) _q- ) (q is an integer of 1-20) or the like can also be used.

  As the PTFE resin, any of a molding powder by a suspension polymerization method, a fine powder by an emulsion polymerization method, and a recycled PTFE resin may be used. Here, the recycled PTFE resin is a PTFE resin that is not a virgin material. For example, a molded product obtained by heating and pressing a molding powder or fine powder at a melting point or higher, or a powder obtained by pulverizing a processed product after heating and firing, In addition, there is a type such as a powder obtained by further irradiating the powder with γ rays or electron beams.

  As the PTFE resin, it is preferable to use a recycled PTFE resin. In order to improve the abrasion resistance of the resin layer, it is preferable to use a PTFE resin having a high molecular weight, but in general, when a PTFE resin of a virgin material having a high molecular weight is used, the resin material increases in viscosity depending on molding conditions. Injection molding may be hindered. On the other hand, by using the regenerated PTFE resin, fiber formation at the time of molding can be prevented, and injection molding inhibition due to thickening does not occur. Moreover, since it is excellent in uniform dispersibility and it is heat-fired, it is excellent also in abrasion resistance. In addition, as a molecular weight of PTFE resin, that whose number average molecular weight (Mn) is about 100,000 to 10 million is preferable.

  The PTFE resin that is the fluororesin (B) is blended in a powder form at the time of melt-kneading at the time of injection molding of the resin material. The average particle diameter of the PTFE resin powder is preferably 5 to 50 μm, and more preferably 9 to 15 μm. If the average particle size is less than 5 μm, the powder aggregates into a lump, and the sliding surface of the slide bearing may not be a smooth surface. Further, if the average particle diameter exceeds 50 μm, the frictional wear characteristics on the sliding surface of the slide bearing may vary.

  Examples of commercially available PTFE resins that can be used in the present invention include Kitamura Co., Ltd .: KTL-610, KTL-450, KTL-350, KTL-8N, KTL-400H, Mitsui DuPont Fluorochemical Co., Ltd .: Teflon (registered trademark). 7-J, TLP-10, Asahi Glass Co., Ltd .: Fullon G163, L150J, L169J, L170J, L172J, L173J, Daikin Industries, Ltd .: Polyflon M-15, Lubron L-5, Hoechst: Hostaflon TF9205, TF9207, etc. Can be mentioned.

  In the resin material, the non-injectable fluororesin (B) is contained in an amount of more than 10% by mass and 40% by mass or less with respect to the total mass (A + B) of the PE resin (A) and the fluororesin (B). . When it is 10% by mass or less, the effect of improving the wear resistance is poor, and 5 MPa · m / min. When using at a PV value exceeding 100%, the wear resistance may be inferior. On the other hand, when it exceeds 40 mass%, there exists a possibility that injection moldability may be inhibited. Preferably, it exceeds 10 mass% and is 30 mass% or less, More preferably, it is 20-30 mass%.

  In addition, an appropriate filler can be added to the resin material forming the resin layer of the slide bearing in order to improve the friction and wear characteristics and reduce the linear expansion coefficient. For example, glass fibers, carbon fibers, pitch-based carbon fibers, PAN-based carbon fibers, aramid fibers, alumina fibers, polyester fibers, boron fibers, silicon carbide fibers, boron nitride fibers, silicon nitride fibers, metal fibers, etc., carbonic acid Examples thereof include minerals such as calcium, talc, silica, clay and mica, inorganic whiskers such as aluminum borate whisker and potassium titanate whisker, and various heat resistant resins such as polyimide resin and polybenzimidazole. If there is a risk of attacking the soft mating material, the fibrous filler is not blended. Furthermore, you may use a well-known additive together with the compounding quantity which does not inhibit the effect of this invention. For example, additives such as antistatic agents (carbon nanofibers, carbon black, graphite, etc.), mold release agents, flame retardants, weather resistance improvers, antioxidants, pigments, and the like may be added as appropriate. The method is not particularly limited.

  A particularly preferable embodiment of the resin material is a case where the resin material is substantially composed of two components of a recycled PTFE resin which is a PE resin (A) and a fluororesin (B) (a pigment or the like may be included as a trace component). In this case, since the fibrous filler is not included and the recycled PTFE resin is not fiberized at the time of molding, the linear expansion coefficient substantially along the flow direction of the resin material (eg, MD (molding direction)) and the resin The linear expansion coefficient substantially along the direction (eg, CD (cross molding direction)) substantially orthogonal to the flow direction of the material can be made substantially the same. Furthermore, by not including lubricating oil (oil-impregnated silica) or the like, the bending elastic modulus and bending strength can be greatly improved as compared with the case of including this. As a result, when the sliding bearing is used under high PV conditions, it is possible to prevent the resin layer from peeling off from the metal base material, deformation of the resin layer itself, uneven wear, and the like. The linear expansion coefficient here is, for example, R.I. T. T. et al. It is an average linear expansion coefficient at (room temperature) to 60 ° C. and can be measured by TMA (thermomechanical analysis) method.

  In the resin material for forming the resin layer of the slide bearing, the means for mixing and kneading the raw materials is not particularly limited, and is mixed with a Henschel mixer, a ball mixer, a ribbon blender, a Redige mixer, etc. Melting and kneading can be performed with a melt extruder such as a shaft extruder to obtain molding pellets. In addition, as a part of the filler material, side feed may be employed when melt-kneading with a twin screw extruder or the like. Using this molding pellet, a resin layer is injection-molded by insert molding on a metal substrate. By adopting injection molding, it is excellent in precision moldability and productivity. Moreover, you may employ | adopt treatments, such as an annealing process, for physical property improvement.

  When only the PE resin (A) is used as the resin base material of the resin material, even when porous silica impregnated with silicone oil is blended as a lubricating component, the PV value is 3 MPa · m / min. However, it was difficult to satisfy the wear resistance when the PV value exceeded this level. On the other hand, the abrasion resistance at a high PV value is remarkably improved by blending the non-injectable fluororesin (B) with the PE resin (A) at a predetermined ratio without using porous silica. (See Examples below). As a result, the plain bearing of the present invention can be suitably used as a substitute for a rolling bearing in many applications.

  The plain bearing of the present invention will be described with reference to FIG. FIG. 1A is a perspective view of a plain bearing, and FIG. 1B is a cross-sectional view taken along line AA. The sliding bearing 1 has a bearing outer peripheral portion 2 formed of a sintered metal base material, and a resin layer using the above-described resin material (molding pellet) on the inner peripheral side which is a sliding portion of the bearing outer peripheral portion 2. 3 is insert-molded through a tunnel gate. The resin layer 3 has a plurality of grooves 4 on the bearing sliding surface, and a gate mark 5 is formed at the bottom of the groove 4. In FIG. 1A, the plurality of grooves 4 are formed as axial grooves 4A and 4B on the radial sliding surface of the cylindrical bearing, and a gate mark 5 is formed at the bottom position of the axial groove 4A. The gate mark 5 is not formed on 4B. Further, the plurality of grooves 4 can be provided on the radial sliding surface, the thrust sliding surface, or both the radial sliding surface and the thrust sliding surface of the cylindrical bearing.

  Insert molding through a tunnel gate can be performed using a known mold structure. Since the tunnel gate trace is formed at the bottom of the groove, no gate processing is required in the molding process, and mass production is possible while having high accuracy.

  The plurality of axial grooves 4 are composed of a groove 4A having a tunnel gate trace and a groove 4B having no tunnel gate trace. Moreover, it arrange | positions so that the distance on the bearing sliding surface from the both sides of the groove | channel 4A to the groove | channel 4B may become equal. Preferably, the same number of grooves A and grooves B are formed at equal intervals. With this arrangement, a weld portion at the time of injection molding is formed in the groove B. Further, the wear powder can be captured in the groove 4 to suppress the occurrence of abnormal wear.

  The bearing outer peripheral portion 2 is a cylindrical member that constitutes the outer peripheral portion of the slide bearing, and is a member having a sliding portion. This sliding part means, for example, one or both of the inner diameter side sliding part and the outer diameter side sliding part for supporting the load in the radial direction, and when supporting the load also in the thrust direction. Includes an end face sliding portion. For example, the sliding portion is at least one of the inner diameter side sliding portion, the outer diameter side sliding portion, and the end surface sliding portion.

  Examples of the material of the sintered metal base material constituting the bearing outer peripheral portion 2 include Fe-based sintered metal, Cu-based sintered metal, and Fe-Cu-based sintered metal, and may include C, Zn, and Sn as components. Good. Further, a small amount of a binder may be added in order to improve moldability and releasability. Further, an aluminum-based material containing Cu, Mg, Si, or a metal-synthetic resin material in which iron powder is bonded with an epoxy-based synthetic resin may be used. Furthermore, in order to improve the adhesion with the resin layer, it is possible to perform a surface treatment or to interpose an adhesive as long as the molding is not hindered.

  An Fe-based sintered metal is preferable in order to obtain a slide bearing excellent in mechanical strength and durability as well as high dimensional accuracy and rotational accuracy. Here, “Fe-based” means that the Fe content is 90% or more by mass ratio. As long as this condition is satisfied, other components such as Cu, Sn, Zn, and C may be contained. “Fe” also includes stainless steel. Fe-based sintered metal is formed by, for example, forming a raw metal powder containing Fe in the above content (a small amount of a binder may be added to improve moldability and releasability) into a predetermined shape, degreasing, The sintered body obtained by firing can be formed by subjecting it to a post-treatment such as sizing, if necessary. The sintered metal has a large number of internal pores due to a porous structure, and the surface has a large number of surface pores formed by opening the internal pores to the outside. The internal pores can be impregnated with the above-described lubricating oil, for example, by vacuum impregnation.

  A resin layer 3 is insert-molded on the sliding portion of the bearing outer peripheral portion 2 made of a sintered metal base material to form a bearing surface that slides with the shaft member. At the time of molding, the molten resin forming the resin layer enters the internal pores of the surface layer portion from the surface opening and solidifies, so that the resin layer adheres firmly to the base surface by a kind of anchor solidification. For this reason, the resin layer is hardly peeled off or dropped off by sliding with the shaft member, and high durability is obtained.

  The surface porosity of the surface on which the resin layer made of a sintered metal substrate is formed is preferably 20 to 50%. If the surface area ratio is less than 20%, the anchor effect on the resin layer cannot be sufficiently obtained, and if the surface area ratio exceeds 50%, the dimensional accuracy and mechanical strength may not be maintained. The “surface aperture ratio” is the ratio (area ratio) of the total area of surface apertures per unit area of the surface.

  Moreover, you may form the bearing outer peripheral part 2 with a molten metal base material. The molten metal material is preferably iron, aluminum, an aluminum alloy, copper, or a copper alloy. Examples of iron include general structural carbon steel (SS400, etc.), mild steel (SPCC, SPCE, etc.), stainless steel (SUS304, SUS316, etc.), and these irons may be plated with zinc, nickel, copper, or the like. . Examples of aluminum include A1100 and A1050, examples of aluminum alloys include A2017 and A5052 (including anodized products), examples of copper include C1100, and examples of copper alloys include C2700 and C2801.

  When the bearing outer peripheral portion 2 is made of a molten metal base material, the joint surface is roughened into an uneven shape by shot blasting, tumbler, machining or the like in order to improve adhesion with the resin layer at the time of insert molding (for example, (Ra 4 μm or more). In addition, chemical surface treatment such as acidic solution treatment (mixed with sulfuric acid, nitric acid, hydrochloric acid, etc., or other solutions), alkaline solution treatment (mixed with sodium hydroxide, potassium hydroxide, etc., or other solutions) is performed. It is preferable to form a fine uneven shape on the joint surface. Since the fine uneven shape formed by the chemical surface treatment has a complicated three-dimensional structure such as a porous structure, the anchor effect can be easily exerted, and strong adhesion can be achieved.

  In the resin layer, (the linear expansion coefficient of the resin material (unit: 1 / ° C.) × (the thickness of the resin layer (unit: μm)) is preferably 0.15 or less, preferably 0.13 or less, 0.10 When the above value is greater than 0.15, the thickness or expansion of the resin layer also increases, and since the outer diameter side of the resin layer is constrained by the metal base, It cannot expand beyond the expansion, but expands toward the inner diameter side, reducing the inner diameter dimension, resulting in a decrease in the clearance with the shaft, and depending on the initial clearance setting, the shaft may be stiff due to temperature rise. In addition, excessive gap fluctuation is not preferable because it causes torque fluctuation, and it is preferable that the gap is small from the viewpoint of rotational accuracy.In addition, dimensional change due to water absorption increases, and excessive gap fluctuation occurs. There is.

  Moreover, the thickness of the resin layer that can be molded is about 50 μm, and if it is thinner than this, formation becomes difficult. Accordingly, the resin expansion coefficient × thickness needs to be 0.003 or more, preferably 0.01 or more, more preferably 0.015 or more.

  The thickness of the resin layer is preferably set to 0.1 to 0.5 mm (100 to 500 μm). The “thickness of the resin layer” in the present invention is the thickness (the thickness in the radial direction) of the surface portion that does not enter the metal substrate. If the thickness of the resin layer is less than 0.1 mm, the durability during long-term use may be poor. On the other hand, if the thickness of the resin layer exceeds 0.5 mm, sink marks may occur and dimensional accuracy may be reduced. In addition, heat due to friction is difficult to escape from the friction surface to the metal substrate, and the friction surface temperature increases. Furthermore, the amount of deformation due to the load increases and the real contact area on the friction surface also increases, which may increase the frictional force and frictional heat generation.

  As the shape of the plain bearing of the present invention, an optimum bearing shape can be selected according to the shape of the sliding portion such as a radial type, a flat plate type, and a flanged bush. Moreover, although the aspect which has a some groove | channel on the bearing sliding surface was demonstrated in FIG. 1, it is not limited to this, The aspect which does not form this groove | channel may be sufficient.

  Moreover, the place which insert-molds to the bearing outer peripheral part of a resin layer will not be specifically limited if it is a sliding part of a bearing outer peripheral part. For example, the cases as shown in FIGS. FIGS. 2A and 2E show a resin layer 3 formed on the radially inner radial sliding surface of the bearing outer peripheral portion 2 in order to support a load in the radial direction. FIGS. 2B, 2C and 2D are views in which a resin layer 3 is formed on the inner radial radial sliding surface and the thrust sliding surface of the bearing outer peripheral portion 2 in order to support loads in the radial direction and the thrust direction. It is. Although not shown, a resin layer can be applied to the outer diameter portion of the bearing as necessary. As shown in FIGS. 2C and 2E, the shape of a resin layer having a hooking portion that does not peel off the outer peripheral portion of the bearing and the resin layer may be adopted.

  As the resin material of the resin layer, the linear expansion coefficient substantially along the flow direction (MD) of the resin material and the linear expansion coefficient substantially along the direction (CD) substantially orthogonal to the flow direction of the resin material are substantially the same. Even when the resin layer is formed in the shape as shown in FIGS. 2B to 2E, the shape / dimensional accuracy with respect to the change in bearing temperature is excellent, and the resin layer is peeled off and deformed. Uneven wear can be prevented.

  The plain bearing of the present invention has high accuracy, excellent sliding characteristics (low friction, low wear), does not attack a soft mating material such as an aluminum shaft, and can also suppress the generation of abnormal noise. For this reason, it can be used as a bearing that supports the rotating shaft of a rotating part in a developing unit, a photosensitive unit, a transfer unit, and the like of office equipment such as a copying machine and a printer. In addition, since it has PE resin as a main component, it can be suitably used mainly in a temperature atmosphere of 80 ° C. or lower.

  Further, 15 MPa · m / min. Since it is possible to use at the above high PV value, it is possible to use a part that is used at a load and speed that is conventionally supported by a rolling bearing instead of the rolling bearing.

  The sliding bearings of Examples and Comparative Examples were manufactured by the following materials and molding methods and subjected to a predetermined friction and wear test.

1. Resin material Base resin;
(A) PE resin that can be injection-molded [trade name Lübmer L5000P manufactured by Mitsui Chemicals, Inc.] (Density (ASTM D 1505): 966 kg / m ³ , MFR (JIS K 7210 (190 ° C., 10 kgf)): 2 g / 10 minutes )
filler;
(B) Recycled PTFE resin (non-injectable fluororesin) [trade name KTL-610 manufactured by Kitamura Co., Ltd.] (average particle diameter (laser diffraction method): 12 μm)
(C) Porous silica [trade name Sunsphere H53 manufactured by AGC S-Itech Co., Ltd.]
(D) Silicone oil [trade name KF-96H manufactured by Shin-Etsu Chemical Co., Ltd.]
These resin materials were blended at the blending ratios shown in Table 1 and melt kneaded with a biaxial extruder to form molding pellets. In Comparative Example 1, a mixture (oil-containing porous silica) having a mixing ratio of porous silica and silicone oil of 1: 3 (mass conversion) was obtained, and this mixture was blended with a resin. Melt-kneading was carried out with an extrusion device to produce molding pellets. A test piece was prepared by injection molding using each resin material, and physical properties were evaluated. The test methods and physical property results are also shown in Table 1.

  As shown in Table 1, it can be seen that the resin material of Example 1 has significantly higher bending strength and flexural modulus than the resin material of Comparative Example 1 containing oil-containing porous silica. Moreover, it turns out that the resin material of Example 1 has the substantially same linear expansion coefficient by the flow direction (MD) and its orthogonal direction (CD).

2. Outer ring made of sintered metal substrate (sintered outer ring)
Size: φ8.5mm (inner diameter), φ16mm (outer diameter), 5mm (height)
Ingredients: copper (0.5-2.5% by mass), other (3% by mass or less), iron (remaining amount)
Manufacturing process: material powder blending, forming, sintering, sizing, rust prevention and drying

3. Insert molding conditions A sintered outer ring having the above-mentioned shape was inserted into a mold, and the molding pellets obtained above were passed through a tunnel gate, and insert molding was performed under the following conditions. The resin layer has a thickness of 0.25 mm. It should be noted that both the examples and comparative examples could be injection molded.
Finished product size: φ8mm (inner diameter), φ16mm (outer diameter), 5mm (height)
Mold temperature: 120 ° C
Molding temperature: 250 ° C
Injection pressure: 100-140 MPa

摩耗係数
ｋ＝δ／（Ｆ×Ｄ）
ｋ：摩耗係数 ｍｍ／（Ｎ×ｍ） 定義：単位仕事量当たりの真円度増加量
Ｆ：ラジアル荷重 Ｎ
Ｄ：総滑り距離 ｍ
δ：摩耗量（真円度の増加量） ｍｍ δ＝δ１−δ０
δ０：試験前の供試軸受の内径２断面真円度（半径法）の平均値
δ１：試験後の供試軸受の内径２断面真円度（半径法）の平均値 4). Friction and wear test A friction and wear test was performed under the conditions shown in Table 2 below. The clearance between the mating material shaft and the slide bearing was 20 μm (measured at 20 ° C.). The wear coefficient was calculated by the following formula. This frictional wear test was performed a plurality of times, and the relationship between the PV value and the wear coefficient was examined. The results are shown in FIG. FIG. 3 is a plot in which the PV value is plotted on the horizontal axis and the wear coefficient is plotted on the vertical axis.

Wear coefficient k = δ / (F × D)
k: Wear coefficient mm / (N × m) Definition: Roundness increase per unit work F: Radial load N
D: Total slip distance m
δ: Amount of wear (increase in roundness) mm δ = δ1-δ0
δ0: Average value of the inner diameter 2 section roundness (radius method) of the test bearing before the test δ1: Average value of the inner diameter 2 section roundness (radius method) of the test bearing after the test

  As shown in FIG. 3, in Comparative Example 1 that contains oil-containing porous silica but does not contain any non-injectable fluororesin, the wear resistance is difficult to be satisfied when the PV value exceeds 3 MPa · m / min. I understand that. Also, at high PV values, the variation in wear coefficient for each measurement is large. On the other hand, in Example 1 including a predetermined amount of non-injectable fluororesin, it has sufficient wear resistance at any of PV values of 5, 10, and 15 MPa · m / min, and the variations thereof. Is also small.

  Since the sliding bearing of the present invention can maintain a low coefficient of friction over a long period of time even under high PV conditions and can keep the price low, it can be suitably used as a substitute for a rolling bearing in office equipment and the like.

DESCRIPTION OF SYMBOLS 1 Slide bearing 2 Bearing outer peripheral part 3 Resin layer 4 Groove 5 Gate trace

Claims (5)

A sliding bearing having a metal base material and a resin layer integrally formed by injection molding using a resin material on a surface which becomes a sliding surface of the base material,
The resin material is a material mainly composed of injection-moldable polyethylene resin (A) and non-injectable fluororesin (B),
The said resin material WHEREIN: The said fluororesin (B) exceeds 10 mass% with respect to the total mass of the said polyethylene resin (A) and the said fluororesin (B), and is contained 40 mass% or less, It is characterized by the above-mentioned. Slide bearing.   The plain bearing according to claim 1, wherein the fluororesin (B) is a recycled polytetrafluoroethylene resin.   The plain bearing according to claim 1 or 2, wherein the fluororesin (B) is blended with the resin material in a powder form having an average particle diameter of 5 to 50 µm.   The polyethylene resin (A) has an MFR of 1 to 30 g / 10 minutes when measured at a load of 10 kg and 190 ° C. based on JIS K 7210. The plain bearing described.   The sliding bearing has a PV value obtained by multiplying the surface pressure (P) and the sliding speed (V) by 5 MPa · m / min. The plain bearing according to any one of claims 1 to 4, wherein the bearing is used under conditions exceeding the above.

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