Resin film for thrust bearings and manufacturing method thereof

Abstract

To provide a resin film for thrust bearings which improves heat resistance or durability, can prevent a recess, etc., from being generated in a bearing portion and can be manufactured in a short time and at low cost, and a manufacturing method thereof.SOLUTION: A resin film 7 for thrust bearings supports a lower end 3 of a rotary shaft 2 of a motor 1, which is an actuator, in a slide contact manner. The resin film for thrust bearings is extrusion-molded by a molding material 9 containing at least a crystalline polyether ether ketone resin. A degree of crystallinity is 7.0% or more to 35.0% or less and a heating dimension change rate in an extrusion direction and a width direction at 200°C and 250°C is -7.9% or more to 5.0% or less when measured according to the JIS K7133, and a taper abrasion amount at 23°C is 3.9 mg or more to 20.0 mg or less when measured according to the JIS K7204. The molding material 9 of the resin film 7 for thrust bearings is the polyether ether ketone resin, thereby obtaining excellent abrasion resistance, heat resistance, etc.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a resin film for thrust bearings used in information devices such as personal computers and mobile phones, office equipment such as copy machines and printers, multimedia equipment such as audio and digital versatile (multipurpose) discs, and home appliances such as cooling fans, and a method for producing the same. [Background technology]

[0002] In recent years, as the market expands, the need for actuators, especially motors, that are light, thin, short, small, and long-lasting has increased, and the development of small, high-speed types has been desired. When these small, high-speed motors are built into information devices, office equipment, and multimedia devices, high speed rotation speeds of over 10,000 rpm are required as the performance of these devices improves, so materials and structures that can withstand high speed rotation have been studied and developed. Specifically, a method has been proposed in which a metal with excellent sliding characteristics and low wear is used for the backing plate of a thrust bearing that comes into contact with the rotating shaft of a motor that exceeds 10,000 rpm. As the metal for the backing plate, stainless steel, iron, and other materials with high hardness have been considered.

[0003] However, when stainless steel or iron is used for the backing plate of the thrust bearing, the weight increases, and high-precision machining is time-consuming and costly. Also, when the rotating shaft and backing plate of the motor are both made of hard metals, wear occurs due to sliding contact, causing durability problems. For these reasons, the design of small, high-speed motors that use metal for the backing plate of the thrust bearing has many problems.

[0004] Therefore, a method has been proposed in which a resin with excellent sliding characteristics and low wear is used for the backing plate of a thrust bearing that comes into contact with the rotating shaft of a motor.For example, (1) a thrust bearing made of polyacetal resin with a surface smoothness in contact with the rotating shaft of a motor of 5 to 1000 μm in terms of center line average roughness (Ra) (see Patent Document 1), and (2) a thrust bearing made of polyamide-imide resin with a surface smoothness in contact with the rotating shaft of a motor of 5 to 1000 μm in terms of center line average roughness (Ra) (see Patent Document 2) have been proposed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2004-52909 A [Patent Document 2] JP 2004-60692 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the case of method (1) where polyacetal resin is used for the thrust bearing, although excellent wear resistance can be obtained, the poor heat resistance causes deformation, cracks, etc. due to frictional heat during sliding contact, resulting in durability problems. In addition, the thrust bearing may not be able to support the load of the motor's rotating shaft, resulting in dents in the thrust bearing. In the case of method (2) where polyamide-imide resin is used for the thrust bearing, although excellent wear resistance can be obtained by improving the heat resistance of the polyamide-imide resin, heat treatment is indispensable after molding to improve the heat resistance and remove residual stress. This heat treatment must be carried out at high temperatures for a long period of time, so the resulting thrust bearing is very expensive.

[0007] The present invention has been made in consideration of the above, and aims to provide a resin film for thrust bearings that has improved heat resistance and durability, can prevent the occurrence of dents and the like in the bearing portion, and can be produced cheaply in a short time, and a method for producing the same. [Means for solving the problem]

[0008] As a result of extensive research, the present inventors focused on crystalline polyether ether ketone resin, which has the most excellent abrasion resistance, heat resistance, sliding properties, and chemical resistance among thermoplastic resins and also has good mechanical properties, and completed the present invention.

[0009] That is, in order to solve the above problems, the present invention provides a device for supporting an end of a rotating shaft of an actuator so as to be in sliding contact therewith, It is extrusion molded from a molding material containing at least a crystalline polyether ether ketone resin, and is characterized by having a crystallinity of 7.0% to 35.0%, a thermal dimensional change rate in the extrusion direction and in the width direction perpendicular to the extrusion direction at 200°C and 250°C being -7.9% to 5.0% when measured in accordance with JIS K7133, and a taper abrasion amount at 23°C being 3.9 mg to 20.0 mg when measured in accordance with JIS K7204.

[0010] When the static friction coefficient and the dynamic friction coefficient at 23° C. are measured in accordance with JIS K7125, it is preferable that the static friction coefficient is 0.05 or more and 0.50 or less, and the dynamic friction coefficient is 0.05 or more and 0.38 or less. It is also preferred that the maximum tensile strength at 23° C. is 50 MPa or more when measured in accordance with JIS K7127, and the tensile elongation at break at 23° C. is 90% or more when measured in accordance with JIS K7127.

[0011] In addition, the tensile modulus at 23° C. is preferably 2000 MPa or more and 5000 MPa when measured in accordance with JIS K7127. In addition, it is desirable that the arithmetic mean roughness at 23° C. is 0.01 μm or more and 2.00 μm or less when measured in accordance with JIS KB0601-2001. In addition, the heat resistance is 1×10 in terms of storage modulus at 250°C. 7 Pa or more 1×10 10 It is better if it is less than Pa.

[0012] The actuator may also comprise a motor, the rotating shaft of which is supported by a radial bearing via a lubricant, a groove being cut circumferentially into either the peripheral surface of the rotating shaft or the inner diameter surface of the radial bearing, and the end of the rotating shaft protruding from the radial bearing being supported so as to be able to slide against the thrust bearing.

[0013] In order to solve the above problems, the present invention provides a method for producing a resin film for a thrust bearing according to claim 1 or 2, comprising the steps of: The method is characterized in that a molding material containing a crystalline polyether ether ketone resin having a crystallinity of at least 7.0% to 35.0% is melt-kneaded, the molding material is extruded from a die into an approximately strip shape, and the extruded molding material is brought into contact with a cooling roll to form a resin film for thrust bearings.

[0014] Here, the actuator in the claims includes at least motors used in information devices, office equipment, multimedia devices, home appliances, air conditioners, etc. Specifically, it includes various DC motors, various AC motors, fan motors, etc. When grooves are cut into either the circumferential surface of the rotating shaft of this motor or the inner diameter surface of the radial bearing, the grooves include at least herringbone grooves. Furthermore, the numerical value "7.0% or more and 35.0% or less" includes measurement error and other numerical values ​​when there is no difference in the effects of the present invention. The numerical value "-7.9% or more and 5.0% or less" includes measurement error and other numerical values ​​when there is no difference in the effects of the present invention.

[0015] The numerical value "3.9 mg or more and 20.0 mg or less" includes measurement error as well as different numerical values ​​if there is no difference in the effect of the present invention. Similarly, the numerical value "50 MPa or more" includes measurement error as well as different numerical values ​​if there is no difference in the effect of the present invention. Similarly, the numerical value "90% or more" includes measurement error as well as different numerical values ​​if there is no difference in the effect of the present invention. Additionally, the up-down, front-back, left-right directions of the resin film for thrust bearings according to the present invention are directions based on the drawings, and can be appropriately changed as necessary.

[0016] The subject of the present invention is a resin film for thrust bearings, but if the configuration of the resin film for other uses is the same as that of the present invention and can be converted to a resin film for thrust bearings, and the effect of the present invention is achieved, the configuration of the other use falls within the technical scope of the present invention. In addition, the resin film for thrust bearings may be transparent, opaque, translucent, unstretched, uniaxially stretched, or biaxially stretched. Biaxial stretching may be performed in a continuous manner or in a batch manner. The resin film for thrust bearings includes both thick resin sheets and thin resin films. Furthermore, the resin film for thrust bearings may be one sheet or multiple sheets.

[0017] According to the present invention, since the molding material of the resin film for thrust bearings is at least polyether ether ketone resin, it is possible to obtain excellent wear resistance, heat resistance, sliding property, chemical resistance, and mechanical properties. In addition, since the crystallinity, thermal dimensional change rate, taper wear amount, etc. of the resin film for thrust bearings are numerically limited, it is possible to sufficiently support the load of the rotating shaft of the actuator and prevent damage, deformation, etc. from occurring in the thrust bearing portion. Effect of the Invention

[0018] According to the present invention, there is an effect that the heat resistance and durability of the resin film for a thrust bearing can be improved, and the occurrence of depressions and the like in the bearing portion can be prevented. In addition, there is an effect that the resin film for a thrust bearing can be produced inexpensively in a short time.

[0019] According to the invention described in claim 2, when the static friction coefficient and the dynamic friction coefficient at 23°C are measured in accordance with JIS K7125, the static friction coefficient is 0.05 to 0.50, and the dynamic friction coefficient is 0.05 to 0.38, so friction is small and it is possible to prevent the occurrence of deformation such as dents and distortion in the thrust bearing due to frictional heat. In addition, wear of the resin film for thrust bearings can be suppressed, so long-term use can be expected.

[0020] According to the invention described in claim 3, the resin film for thrust bearings has a maximum tensile strength of 50 MPa or more and an elongation at break of 90% or more, so that the resin film for thrust bearings can have sufficient toughness and can prevent problems such as breakage, cracking, and tearing in the resin film for thrust bearings when the thrust bearing is used.

[0021] According to the invention described in claim 4, when the rotating shaft of the motor rotates, the lubricant in the radial bearing is collected in the groove, generating dynamic pressure, making it possible to support the rotating shaft of the motor with high precision. According to the invention of claim 5, since the melt extrusion molding method is adopted as the manufacturing method of the resin film for thrust bearings, it becomes possible to continuously manufacture the resin film for thrust bearings in a substantially strip shape. In addition, it is expected that the thickness precision, productivity, and handling properties of the resin film for thrust bearings can be improved, and the equipment can be simplified. [Brief description of the drawings]

[0022] [Figure 1] 1 is an explanatory diagram illustrating an embodiment of a resin film for a thrust bearing according to the present invention; [Diagram 2] 1 is an overall explanatory view that typically illustrates an embodiment of a resin film for a thrust bearing and a method for producing the same according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] A preferred embodiment of the present invention will now be described with reference to the drawings. As shown in FIG. 1, a resin film 7 for thrust bearings in this embodiment is a resin film that slidably supports the end of a rotating shaft 2 of a motor 1, which is an actuator, as a receiving plate for a thrust bearing 6, and is extrusion-molded from a molding material 9 containing at least a crystalline polyether ether ketone resin. The resin film 7 has a crystallinity of 7.0% to 35.0%, a thermal dimensional change rate in the extrusion direction and width direction at 200°C and 250°C of -7.9% to 5.0%, and a taper wear amount at 23°C of 3.9 mg to 20.0 mg, thereby contributing to the achievement of Goal 9 of the SDGs adopted at the United Nations Summit.

[0024] Motor 1 may be, for example, a small, high-speed spindle motor or a DC motor, and has a lower end 3 of a highly hard rotating shaft 2 extending downward, which is formed into a flat surface or curved into a substantially hemispherical shape. In this motor 1, a plurality of herringbone grooves 4 extending circumferentially are arranged at predetermined intervals in the axial direction of rotating shaft 2, a lower portion of rotating shaft 2 is supported by radial bearing 5 penetrating therethrough so that the herringbone grooves 4 face the inner peripheral surface of radial bearing 5, and the lower end 3 of rotating shaft 2 protruding from radial bearing 5 is supported from below by thrust bearing resin film 7, which is a receiving plate for thrust bearing 6, so as to be in sliding contact with the thrust bearing resin film 7.

[0025] Lubricant 8 such as oil or grease that exhibits a wear-suppressing function is filled or applied as necessary between the rotatable rotating shaft 2 of motor 1 and the inner diameter surface of radial bearing 5, and between the lower end 3 of rotating shaft 2 and thrust bearing resin film 7, which is the backing plate for thrust bearing 6. In such a motor 1, when rotating shaft 2 rotates, lubricant 8 is collected in the multiple herringbone grooves 4, generating dynamic pressure and functioning to support rotating shaft 2 rotating at high speed with high precision.

[0026] For example, a ball bearing or a deep groove ball bearing is used as the radial bearing 5. The molding material 9 of the resin film 7 for thrust bearing is prepared with at least polyether ether ketone (PEEK) resin as the main component, and contains 51 mass % or more and 100 mass % or less, preferably 75 mass % or more and 100 mass % or less, more preferably 90 mass % or more and 100 mass % or less, and further preferably 95 mass % or more and 100 mass % or less of this polyether ether ketone resin.

[0027] Polyether ether ketone resin is a crystalline thermoplastic resin consisting of arylene groups, ether groups, and carbonyl groups, and is made of resins described in the literature, for example, [Asahi Research Center Co., Ltd.: Super engineering plastic PEEK growing in cutting-edge applications (part 1)], and is characterized by excellent mechanical properties, light weight, electrical insulation, hydrolysis resistance, heat resistance, sliding properties, abrasion resistance, chemical resistance, etc. A specific example of this polyether ether ketone resin is polyether ether ketone resin represented by chemical formula (1).

[0028] [ka]

[0029] In terms of improving mechanical properties, n in this chemical formula is 10 or more, preferably 20 or more. The polyether ether ketone resin may be a homopolymer consisting of only the repeating unit of chemical formula (1), but may also have a repeating unit other than chemical formula (1). In addition, the proportion of the chemical structure of chemical formula (1) in the polyether ether ketone resin is 51 mol % or more, preferably 70 mol % or more, more preferably 85 mol % or more, and even more preferably 95 mol % or more, relative to 100 mol % of the polyether ether ketone resin. This is because within this range, a resin film 7 for thrust bearings having excellent heat resistance, mechanical properties, electrical insulation, etc. can be obtained.

[0030] The polyether ether ketone resin may be a block copolymer, a random copolymer, or a modified product with other copolymerizable monomers, as long as the effect of the present invention is not impaired. The glass transition temperature of this polyether ether ketone resin is usually 130°C or higher and 160°C or lower, preferably 135°C or higher and 155°C or lower, and more preferably 140°C or higher and 150°C or lower. The melting point (also called melting temperature) is usually 320°C or higher and 360°C or lower, preferably 335°C or higher and 350°C or lower, and it is generally used in a form suitable for molding such as powder, granules, or pellets. The melting point (unit: °C) of this polyether ether ketone resin can be determined by thermal analysis using a differential scanning calorimeter.

[0031] Examples of such polyether ether ketone resin products include, for example, Victrex Powder series and Victrex Granules series manufactured by Victrex, Vestakeep series manufactured by Polypla-Evonik, and KetaSpire PEEK series manufactured by Solvay Specialty Polymers.

[0032] Examples of methods for producing polyether ether ketone resins include those described in JP-A-50-27897, JP-A-51-119797, JP-A-52-38000, JP-A-54-90296, JP-B-55-23574, JP-B-56-2091, and Japanese Patent No. 5702283. Representative production methods include, but are not limited to, a method in which an aromatic diol component and an aromatic dihalide component (wherein one of the components contains at least a component having a carbonyl group) are polycondensed in the presence of an alkali metal salt and a solvent at a temperature range of 150° C. to 400° C.

[0033] An example of the aromatic diol component is hydroquinone, and an example of the aromatic dihalide component is 4,4'-difluorobenzophenone. An example of the alkali metal salt is inorganic potassium carbonate, and an example of the solvent is diphenylsulfone. After the polycondensation reaction is completed, the product can be pulverized, washed with acetonitrile, methanol, ethanol, water, and dried.

[0034] When using the polyether ether ketone resin, the crystallization temperature may be appropriately adjusted by modifying the terminal group (usually a halogen atom) with an alkaline sulfonate group (sodium sulfonate group, potassium sulfonate group, lithium sulfonate group, etc.); however, it is preferable to use the polyether ether ketone resin without modifying the terminal group.

[0035] The apparent shear viscosity of polyether ether ketone resin is 1.0×10 at 375°C. 2 sec -1 In the case of , 1.0 × 10 2 Pa·s or more 1.0×10 4 Pa s or less, preferably 2.0×10 2 Pa·s or more 5.0×10 3 Pa s or less, preferably 2.5×10 2 Pa·s or more 2.5×10 3 Pa s or less, more preferably 5.0×10 2 Pa·s or more 2.0×10 3 The range is set to Pa·s or less.

[0036] This is because the apparent shear viscosity of polyether ether ketone resin is 1.0 × 10 2 If it is less than Pa s, the melt tension of the molten polyether ether ketone resin is small, causing problems in the formability of the resin film 7 for thrust bearings, and further reducing toughness, making it difficult to prevent problems such as breakage, cracking, and splitting when used as a backing plate for the thrust bearing 6. In addition, when the resin film 7 for thrust bearings is processed into a backing plate, splitting, tearing, and cracks may occur, making it difficult to process the backing plate.

[0037] In contrast, the apparent shear viscosity of polyether ether ketone resin is 1.0×10 4 If it exceeds Pa·s, the shear viscosity of the polyetheretherketone resin will be high, causing difficulties in melt extrusion molding of the polyetheretherketone resin. The apparent shear viscosity of this polyetheretherketone resin can be measured using a commercially available shear viscosity / extensional viscosity measuring device.

[0038] In addition to polyether ether ketone resin, polyarylene ether ketone resins such as polyether ketone (PEK) resin, polyether ketone ketone (PEKK) resin, polyether ether ketone ketone (PEEKK) resin, and polyether ketone ether ketone ketone (PEKEKK) resin can be added to the molding material 9 as needed, within the scope that does not impair the characteristics of the present invention.

[0039] The molding material 9 includes, in addition to polyether ether ketone resin, polyolefin resins such as polyethylene (PE) resin, polypropylene (PP) resin, polymethylpentene (PMP) resin, and polystyrene (PS) resin, acid-modified olefin resins such as maleic anhydride-modified polyethylene resin and maleic anhydride-modified polypropylene resin, polyester resins such as polyethylene terephthalate (PET) resin, polybutylene terephthalate (PBT) resin, and polyethylene naphthalate (PEN) resin, polyimide (PI) resin, Polyimide resins such as polyamideimide (PAI) resin and polyetherimide (PEI) resin, polyamide 4T (PA4T) resin, polyamide 6T (PA6T) resin, modified polyamide 6T (modified PA6T) resin, polyamide 9T (PA9T) resin, polyamide 10T (PA10T) resin, polyamide 11T (PA11T) resin, polyamide 6 (PA6) resin, polyamide 66 (PA66) resin, polyamide 46 (PA46) resin, and other polyamide resins, polysulfone (PSU) resin, polyethersulfone (P Polysulfone resins such as polyphenylene sulfide (PPS) resin, polyphenylene sulfide ketone resin, polyphenylene sulfide sulfone resin, polyphenylene sulfide ketone sulfone resin, polyarylene sulfide resins such as polytetrafluoroethylene (PTFE) resin, polytetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) resin, tetrafluoroethylene-hexafluoropropyl copolymer (FEP) resin, tetrafluoroethylene-ethylene copolymer (ETFE) resin, polychlorotrifluoroethylene (PCTFE) resin, polyvinylidene fluoride (PVdF) resin, vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer resin, acid-modified fluororesin, and thermoplastic resins such as polycarbonate (PC) resin, polyarylate (PAR) resin, polyacetal (POM) resin, liquid crystal polymer (LCP), and aliphatic polyketone resin can be selectively added.

[0040] In addition to the polyether ether ketone resin, various additives, such as a crystal nucleating agent, an antioxidant, a heat stabilizer, a slipping agent, an antistatic agent, an antiblocking agent, a lubricant, a viscosity modifier, and a coloring inhibitor, may be added to the molding material 9 within a range that does not impair the object of the present invention. In addition, various particles may be contained in the polyether ether ketone resin of the molding material 9. As the particles, inorganic particles or organic particles that contribute to improving the sliding property are preferable.

[0041] Examples of inorganic particles include metal oxides such as silica, alumina, titanium dioxide, and zirconia, as well as barium sulfate, calcium carbonate, aluminum silicate, calcium phosphate, mica, talc, kaolin, clay, and zeolite. Among these, metal oxides such as silica, alumina, titanium dioxide, and zirconia are preferred.

[0042] In contrast, the organic particles may be one of the following: crosslinked particles of dimethylpolysiloxane, crosslinked particles of polymethoxysilane-based compounds, cured polyorganosilsesquioxane particles, crosslinked particles of polystyrene-based compounds, crosslinked particles of acrylic compounds, crosslinked particles of polyurethane-based compounds, crosslinked particles of polyester-based compounds, crosslinked particles of fluorine-based compounds, fullerenes, carbon nanotubes, graphene, graphite, and carbon black, which may be used alone or in combination of two or more.

[0043] The average particle size of the inorganic particles or organic particles is preferably in the range of 0.01 μm to 10.0 μm, more preferably 0.05 μm to 8.0 μm, more preferably 0.1 μm to 6.0 μm, and even more preferably 0.1 μm to 5.0 μm.

[0044] This is because, when the average particle size of the inorganic particles or organic particles is less than 0.01 μm, the melt viscosity of the molding material 9 increases, making it difficult to perform melt extrusion molding of the polyether ether keto resin. In addition, because the inorganic particles or organic particles have high cohesiveness and poor dispersibility, they do not disperse uniformly in the resin film 7 for thrust bearings, but form aggregates (lumps), resulting in a problem of reduced mechanical properties of the resin film 7 for thrust bearings. On the other hand, when the average particle size of the inorganic particles or organic particles exceeds 10.0 μm, the mechanical properties of the resin film 7 for thrust bearings are reduced, causing the resin film 7 for thrust bearings to break or crack during processing.

[0045] The average particle size of inorganic particles or organic particles can be measured by calculating the weight average diameter using the circle equivalent diameter obtained by image processing of a transmission electron microscope photograph of the particles.

[0046] The amount of inorganic particles or organic particles added is preferably in the range of 0.01 parts by mass to 10.0 parts by mass, preferably 0.01 parts by mass to 7.5 parts by mass, more preferably 0.5 parts by mass to 5.0 parts by mass, and even more preferably 1.0 parts by mass to 5.0 parts by mass, based on 100 parts by mass of polyether ether ketone resin. This is because if the amount of particles added is less than 0.01 parts by mass, it will cause insufficient handling. Also, if the amount of particles added exceeds 10.0 parts by mass, the mechanical properties of the resin film 7 for thrust bearings will decrease, and the resin film 7 for thrust bearings will break or crack during processing.

[0047] In order to prevent aggregation of inorganic particles or organic particles or to improve affinity with polyether ether ketone resin, a silane coupling agent (vinyl trimethoxysilane, vinyl triethoxysilane, 3-glycidoxypropyl trimethoxysilane, 3-methacryloxypropyl trimethoxysilane, 3-aminopropyl ethoxysilane, p-styryl trimethoxysilane, 3-methacryloxypropyl methyl dimethyl silane, etc.) may be added to the inorganic particles or organic particles within a range that does not impair the properties of the thrust bearing resin film 7. silane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, tris-(trimethoxysilylpropyl)isocyanurate, 3-ureidopropyltrialkoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-isocyanatopropyltriethoxysilane, 3-trimethoxysilylpropylsuccinic anhydride, imidazole silane, etc.], titanate coupling agents [isopropyltrimethoxysilane, sostearoyl titanate, isopropyl (dioctyl pyrophosphate) titanate, isopropyl tris(N-aminoethyl-aminoethyl) titanate, tetraoctyl bis(di-tridecyl phosphite) titanate, tetra(2,2-diallyloxymethyl-1-butyl) bis(di-tridecyl) phosphite titanate, bis(dioctyl pyrophosphate) oxyacetate titanate, bis(dioctyl pyrophosphate) ethylene titanate, isopropyl trioctanoyl titanate It is possible to treat the resin with various coupling agents such as isopropyl dimethacryl isostearoyl titanate, isopropyl tridecylbenzenesulfonyl titanate, isopropyl isostearoyl diacryl titanate, isopropyl tri(dioctyl phosphate) titanate, isopropyl tricumyl phenyl titanate, tetraisopropyl (dioctyl phosphite) titanate, and aluminate coupling agents such as acetoalkoxyaluminum diisopropylate.

[0048] The amount of the coupling agent added is, relative to 100 parts by mass of the inorganic particles or organic particles, in the range of 0.01 parts by mass or more and 5.0 parts by mass or less, preferably 0.1 parts by mass or more and 3.0 parts by mass or less, more preferably 0.5 parts by mass or more and 2.0 parts by mass or less, and even more preferably 0.5 parts by mass or more and 1.5 parts by mass or less.

[0049] This is because, if the amount of the coupling agent added is less than 0.01 parts by mass, it may not be possible to prevent the particles from agglomerating, or it may not be possible to improve the affinity with the polyetheretherketone resin, which may result in a decrease in mechanical strength or a decrease in dispersibility in the polyetheretherketone resin.In contrast, if the amount of the coupling agent added is more than 5.0 parts by mass, the mechanical properties of the resin film 7 for thrust bearings will deteriorate due to excessive addition.

[0050] The resin film 7 for thrust bearings is manufactured by a predetermined molding method so that the crystallinity is 7.0% or more and 35.0% or less, preferably 7.0% or more and 33.0% or less, more preferably 7.1% or more and 30.0% or less, and even more preferably 7.2% or more and 27.0% or less.

[0051] This is because if the crystallinity of the resin film 7 for thrust bearings is less than 7.0%, it becomes difficult to rapidly cool the resin film 7 for thrust bearings, making molding difficult. On the other hand, if the crystallinity of the resin film 7 for thrust bearings exceeds 35.0%, the toughness of the resin film 7 for thrust bearings decreases and it becomes brittle, causing breakage, tearing, or cracking when the resin film 7 for thrust bearings is processed into a backing plate. In addition, a long heat treatment at high temperature is required, which makes the resin film 7 for thrust bearings expensive.

[0052] The crystallinity of the resin film 7 for a thrust bearing is calculated by the following formula based on the results of thermal analysis using a differential scanning calorimeter. Crystallinity (%)={(ΔHm-ΔHc) / ΔHx}×100…(Formula 1) Where, ΔHm: Heat of crystal melting peak of resin film for thrust bearing (J / g) ΔHc: Heat quantity at the recrystallization peak of the resin film for thrust bearings (J / g) ΔHx: Melting energy of 100% crystallized resin film for thrust bearings This is the theoretical value, 130 J / g.

[0053] Examples of molding methods for the resin film 7 for thrust bearings include melt extrusion molding, calendar molding, casting, etc. Among these molding methods, from the viewpoints of improving the thickness accuracy, productivity, and handleability of the resin film 7 for thrust bearings, and simplifying the equipment, the melt extrusion molding method, which can continuously extrude the resin film 7 for thrust bearings into a strip shape, is optimal.

[0054] The melt extrusion molding method, as shown in FIG. 2, is a method in which a molding material 9 containing polyether ether ketone resin is melt-kneaded using a melt extruder 10, the molten polyether ether ketone resin is continuously extruded in a strip shape from a die 14, such as a T-die or a round die, connected to the tip of the melt extruder 10, and the polyether ether ketone resin is sandwiched between a pressure roll 17 and a cooling roll 18 and cooled, thereby producing a resin film 7 for a thrust bearing.

[0055] The melt extrusion molding machine 10 is, for example, a single-screw extruder or a twin-screw extruder, and has a raw material inlet 11 for the molding material 9 disposed at the upper rear portion. This raw material inlet 11 is connected to an inert gas supply pipe 12 which supplies an inert gas such as helium gas, neon gas, argon gas, krypton gas, nitrogen gas, etc. as needed. The supply of inert gas from this inert gas supply pipe 12 effectively prevents oxidative deterioration, oxygen crosslinking, and thermal crosslinking of the molding material 9.

[0056] The melting temperature during melt kneading in the melt extrusion molding machine 10 is not particularly limited as long as it is a temperature at which melt kneading dispersion is possible and polyetheretherketone resin does not decompose, but it is preferably in the range of the melting point (hereinafter referred to as Tm) of polyetheretherketone resin or more and less than the thermal decomposition temperature of polyetheretherketone resin. It is preferably [Tm of polyetheretherketone resin + 10°C] or more and [Tm of polyetheretherketone resin + 100°C] or less, more preferably [Tm of polyetheretherketone resin + 20°C] or more and [Tm of polyetheretherketone resin + 70°C] or less, and even more preferably [Tm of polyetheretherketone resin + 30°C] or more and [Tm of polyetheretherketone resin + 60°C] or less. The Tm (unit: °C) of the polyetheretherketone resin can be obtained by thermal analysis using a differential scanning calorimeter.

[0057] Specifically, the optimum temperature range is from 360° C. to 450° C., preferably from 360° C. to 420° C., and more preferably from 370° C. to 400° C. This is because if the temperature during melt kneading in the melt extruder 10 is below the Tm of the polyether ether ketone resin, the polyether ether ketone resin will not have melt fluidity, and it will be impossible to mold the resin film 7 for thrust bearings by melt extrusion molding. On the other hand, if the temperature is above the thermal decomposition temperature, the polyether ether ketone resin will be decomposed.

[0058] The die 14 is connected to the tip of the melt extruder 10 via a connecting pipe 13, and functions to continuously extrude a strip of polyether ether ketone resin downward. There are various types of this die 14, but a T-die is preferable because it is possible to obtain a resin film 7 for thrust bearings with excellent thickness accuracy.

[0059] A gear pump 15 and a filter 16 are preferably attached to the connecting pipe 13 upstream of the die 14. The gear pump 15 functions to transfer the molding material 9 melt-kneaded by the melt extruder 10 at a constant flow rate and with high precision to the downstream die 14 via the filter 16. The filter 16 also functions to separate unmelted polyetheretherketone resin and foreign matter from the molten polyetheretherketone resin and transfer the molten polyetheretherketone resin to the die 14.

[0060] The filter 16 is made of, for example, a circle with many concentric holes, a sintered metal with many holes, or a metallic mesh, and has a plurality of small openings that are 0.5 to 6 times, preferably 0.5 to 4 times, and more preferably 0.5 to 3.8 times the average thickness of the resin film 7 for thrust bearings. The reason why the thickness is 0.5 times or more the average thickness of the resin film 7 for thrust bearings is that if the thickness is less than 0.5 times, the extrusion pressure of the molding material 9 will be high, which may cause damage to the filter 16 and also significantly reduce productivity.

[0061] The temperature of the die 14 during extrusion is preferably in the range of Tm of the polyetheretherketone resin or more and less than the thermal decomposition temperature of the polyetheretherketone resin, preferably Tm of the polyetheretherketone resin + 10°C or more and Tm of the polyetheretherketone resin + 100°C or less, more preferably Tm of the polyetheretherketone resin + 20°C or more and Tm of the polyetheretherketone resin + 70°C or less, and even more preferably Tm of the polyetheretherketone resin + 30°C or more and Tm of the polyetheretherketone resin + 60°C or less.

[0062] Specifically, the optimum temperature range is from 360° C. to 450° C., preferably from 360° C. to 420° C., and more preferably from 370° C. to 400° C. This is because, if the temperature is below the Tm of the polyether ether ketone resin, the polyether ether ketone resin does not have melt fluidity, and therefore the resin film 7 for thrust bearings cannot be molded by melt extrusion molding. On the other hand, if the temperature is equal to or higher than the thermal decomposition temperature, the polyether ether ketone resin will decompose.

[0063] Below the die 14, a pair of pressure rolls 17 facing each other with a gap therebetween are rotatably supported, and between the pair of pressure rolls 17, a plurality of cooling rolls 18 arranged in a row and in sliding contact with each other are rotatably supported, and among the plurality of cooling rolls 18, the upstream cooling roll 18 and the downstream cooling roll 18 each slide against the circumferential surface of the pressure roll 17. Each pressure roll 17 is configured to have a reduced diameter, and each cooling roll 18 is configured to have a larger diameter than the pressure roll 17.

[0064] Of the pair of pressure-bonding rolls 17, a winder 20 is installed downstream of the downstream pressure-bonding roll 17, which winds up the resin film 7 for thrust bearings around a rotatable winding tube 19. Between this winder 20 and the downstream pressure-bonding roll 17, a slit blade 21 which forms a slit in the longitudinal direction of the side of the resin film 7 for thrust bearings is arranged so that it can be raised and lowered. Between this slit blade 21 and the winder 20, the required number of tension rolls 22 are supported on the axis of rotation to apply tension to the resin film 7 for thrust bearings to smoothly wind it up.

[0065] Each pressure roller 17 is adjusted to a temperature range of from (glass transition temperature of the resin film for thrust bearings (hereinafter, glass transition temperature is referred to as Tg) -100°C) to (Tm of the resin film for thrust bearings), preferably from (Tg of the resin film for thrust bearings -70°C) to (Tm of the resin film for thrust bearings -50°C), more preferably from (Tg of the resin film for thrust bearings -40°C) to (Tm of the resin film for thrust bearings -100°C), and even more preferably from (Tg of the resin film for thrust bearings -10°C) to (Tm of the resin film for thrust bearings -120°C), and is pressure-contacted to the resin film for thrust bearings 7. The Tg (unit: °C) of the resin film for thrust bearings 7 can be determined by thermal analysis using a differential scanning calorimeter.

[0066] A specific temperature range is 50°C or more and less than 345°C, preferably 80°C or more and less than 285°C, more preferably 100°C or more and less than 245°C, and even more preferably 130°C or more and less than 225°C. The reason why the temperature of the pressure roll 17 is in this range is that if it is less than [Tg of the resin film for thrust bearings - 100°C], the melt-extruded strip-shaped polyether ether ketone resin cannot be brought into close contact with the cooling roll 18, and therefore a smooth resin film for thrust bearings 7 cannot be obtained. On the other hand, if it exceeds the Tm of the resin film for thrust bearings 7, the resin film for thrust bearings 7 may stick to the peripheral surface of the pressure roll 17 and break, or the strength of the resin film for thrust bearings 7 may decrease and break.

[0067] The method for adjusting the temperature of the pressure roller 17 is not particularly limited, but examples thereof include a method using a heat transfer medium such as air, water, or oil, a method using an electric heater, and a method utilizing induction heating.

[0068] From the viewpoint of improving the adhesion between the thrust bearing resin film 7 and the cooling roll 18, the peripheral surface of each pressure roller 17 is coated with a rubber layer such as at least natural rubber, isoprene rubber, butadiene rubber, norbornene rubber, acrylonitrile butadiene rubber, nitrile rubber, urethane rubber, silicone rubber, fluororubber or the like as necessary, and an inorganic compound such as silica or alumina is selectively added to this rubber layer. Of these rubbers, it is preferable to select silicone rubber or fluororubber, which have excellent heat resistance.

[0069] As the pressure roller 17, a metal elastic roller having a metal surface is used as necessary, and when this metal elastic roller is used, it is possible to form the resin film 7 for thrust bearings having an excellent surface smoothness. Specific examples of this metal elastic roller include a metal sleeve roller, an air roller (manufactured by Dymco: product name), and a UF roller (manufactured by Hitachi Zosen: product name). In addition, the pressure roller 17 whose surface is covered with a fluororesin film such as polytetrafluoroethylene-perfluoroalkylvinylether copolymer (PFA) resin or tetrafluoroethylene-hexafluoropyrene copolymer (FEP) resin can also be used in the same way, since it is possible to form the resin film 7 for thrust bearings having an excellent surface smoothness.

[0070] The multiple cooling rolls 18 are, for example, metal rolls with a larger diameter than the pressure roll 17, and are rotatably supported below the die 14 to clamp the polyether ether ketone resin extruded into a strip shape between them and the pressure roll 17. Together with the pressure roll 17, they function to cool the resin film 7 for thrust bearings in a short period of time while controlling its thickness within a predetermined range.

[0071] The cooling roll 18, like the pressing roll 17, is adjusted to a temperature range of [Tg of the resin film for thrust bearings - 100°C] or more and less than [Tm of the resin film for thrust bearings], preferably [Tg of the resin film for thrust bearings - 70°C] or more and [Tm of the resin film for thrust bearings - 50°C] or less, more preferably [Tg of the resin film for thrust bearings - 40°C] or more and [Tm of the resin film for thrust bearings - 100°C] or less, and even more preferably [Tg of the polyether ether ketone resin] or more and [Tm of the resin film for thrust bearings - 120°C] or less, and is pressed against the resin film for thrust bearings 7.

[0072] A specific temperature range is 50°C or higher and lower than 345°C, preferably 80°C or higher and 285°C or lower, more preferably 100°C or higher and 245°C or lower, and further preferably 130°C or higher and 225°C or lower.

[0073] The reason why the temperature of the cooling roll 18 is within this range is that if it is below [Tg of the resin film for thrust bearings - 100°C], the melt-extruded strip-shaped polyether ether ketone resin cannot be brought into close contact with the cooling roll 18, making it impossible to obtain a smooth resin film for thrust bearings 7. On the other hand, if it exceeds the Tm of the resin film for thrust bearings 7, the resin film for thrust bearings 7 may stick to the peripheral surface of the cooling roll 18 and break, or the strength of the resin film for thrust bearings 7 may decrease and break.

[0074] The method for adjusting the temperature of the cooling roll 18 is not particularly limited, but examples thereof include a method using a heat transfer medium such as air, water, or oil, a method using an electric heater, and a method utilizing induction heating.

[0075] After the molding material 9 has been extruded into a strip, the molding material 9 is wound around a pair of pressure-bonding rolls 17, multiple cooling rolls 18, a tension roll 22, and a winding tube 19 of a winding machine 20, and both sides of the resin film 7 for thrust bearings are cut longitudinally with a slit blade 21. The resin film 7 is then sequentially wound around the winding tube 19 of the winding machine 20, thereby producing a long resin film 7 for thrust bearings.

[0076] The thickness of the resin film 7 for thrust bearings manufactured by cooling with the cooling roll 18 is preferably 25 μm to 1000 μm, more preferably 50 μm to 800 μm, more preferably 75 μm to 600 μm, and even more preferably 100 μm to 500 μm. This is because if the resin film 7 for thrust bearings is less than 25 μm in thickness, problems will arise with its life as a backing plate, and if it exceeds 1000 μm, it will be difficult to make the motor 1 thinner.

[0077] The surface of the produced resin film 7 for thrust bearings can be formed with fine irregularities to reduce the coefficient of friction of the surface. Examples of methods for forming the fine irregularities include (1) a method in which polyetheretherketone resin is melt-kneaded by a melt extrusion molding machine 10, the melt-kneaded polyetheretherketone resin is extruded from a T-die onto a cooling roll 18 having a fine irregularity on its circumferential surface, and the resin film 7 for thrust bearings is sandwiched between the cooling roll 18 and a pressure roller 17 to form the fine irregularities, (2) a method in which minute inorganic compounds such as zirconia, glass, and stainless steel, polycarbonate resin, polyamide resin, or organic compounds such as plant seeds are sprayed onto the resin film 7 for thrust bearings to form the fine irregularities, and (3) a method in which the resin film 7 for thrust bearings is press-molded with a mold having fine irregularities to form the fine irregularities.

[0078] Among these methods, method (1) is optimal from the viewpoints of simplifying the equipment, precision of the unevenness size, uniformity of the unevenness formation, ease of unevenness formation, and continuous unevenness formation.

[0079] To explain the forming method of (1) in more detail, there are (1-1) a method in which polyether ether ketone resin is discharged from a T-die of a melt extrusion molding machine 10 onto a cooling roll 18 having fine irregularities on its peripheral surface, and this discharged material is sandwiched between the cooling roll 18 and a pressure roller 17 having fine irregularities on its peripheral surface, and molded simultaneously with the melt extrusion molding of the resin film 7 for thrust bearings, and (1-2) a method in which the molded resin film 7 for thrust bearings is sandwiched between a cooling roll 18 having fine irregularities on its peripheral surface and a pressure roller 17 having fine irregularities on its peripheral surface, and the unevenness is formed. Of these, the forming method of (1-1) is the most suitable from the viewpoint of simplifying the equipment.

[0080] The produced resin film 7 for thrust bearings has a Tg of usually 130° C. or more and 160° C. or less, preferably 135° C. or more and 155° C. or less, and more preferably 140° C. or more and 150° C. or less. The resin film 7 for thrust bearings has a Tm of usually 320° C. or more and 360° C. or less, and preferably 335° C. or more and 350° C. or less.

[0081] The thermal dimensional stability of the resin film 7 for thrust bearings can be evaluated from the thermal dimensional changes in the extrusion direction (hereinafter abbreviated as "MD") and the width direction (hereinafter abbreviated as "TD"). Specifically, the thermal dimensional stability of the resin film 7 for thrust bearings after heat treatment at 200°C and 250°C can be evaluated from the thermal dimensional change rate measured in accordance with JIS K7133. Here, a positive value for the thermal dimensional change rate indicates elongation, and a negative value indicates shrinkage.

[0082] The thermal dimensional change rate of the resin film 7 for thrust bearings at 200° C. and 250° C. is optimally in the range of −7.9% to 5.0%, preferably −5.0% to 4.5%, more preferably −4.5% to 3.5%, and even more preferably −4.0% to 1.0%. This is because when the thermal dimensional change rate is in the range of −7.9% to 5.0%, thermal dimensional stability can be maintained and warping or bending of the resin film 7 for thrust bearings can be prevented.

[0083] The amount of wear of the resin film 7 for thrust bearings can be evaluated by the amount of taper wear under an environment of 23°C±2°C and 50% RH±5% RH. This amount of taper wear can be measured in accordance with JIS K7204. The amount of taper wear of the resin film 7 for thrust bearings is 3.9 mg or more and 20 mg or less, preferably 3.9 mg or more and 17 mg or less, more preferably 3.9 mg or more and 13 mg or less, and even more preferably 3.9 mg or more and 10 mg or less.

[0084] This is because, if the amount of taper wear is less than 3.9 mg, there is a risk that the resin film 7 for thrust bearings will be deformed due to heat generated by friction between the rotating shaft 2 and the backing plate of the thrust bearing 6. On the other hand, if the amount of taper wear exceeds 20 mg, the amount of wear increases, causing a problem in terms of extending the life of the resin film 7 for thrust bearings.

[0085] The sliding properties of the resin film 7 for thrust bearings can be evaluated by the static and dynamic friction coefficients in an environment of 23°C±2°C and 50% RH±5% RH. The static and dynamic friction coefficients of the resin film 7 for thrust bearings can be evaluated in MD and TD. These static and dynamic friction coefficients can be measured in accordance with JIS K7125.

[0086] The static friction coefficient (MD, TD) of the resin film 7 for thrust bearings at 23°C is preferably in the range of 0.05 to 0.50, preferably 0.15 to 0.45, more preferably 0.20 to 0.40, and even more preferably 0.25 to 0.38. This is because if the static friction coefficient is outside the range of 0.05 to 0.50, the slidability is low, resulting in high friction, and deformation such as dents and distortion occurs in the resin film 7 for thrust bearings of the thrust bearing 6 due to frictional heat. In addition, wear occurs, which is a problem in terms of extending the life of the film.

[0087] The dynamic friction coefficient of the resin film 7 for thrust bearings at 23°C is preferably in the range of 0.05 to 0.38, more preferably 0.06 to 0.35, more preferably 0.07 to 0.30, and even more preferably 0.08 to 0.25. This is because if the dynamic friction coefficient is outside the range of 0.05 to 0.38, the slidability is low, so friction is large, and deformation such as dents and distortion occurs in the resin film 7 for thrust bearings due to frictional heat. In addition, wear occurs, which is a problem in terms of extending the life of the film.

[0088] The rigidity of the resin film 7 for thrust bearings can be evaluated by its tensile modulus in an environment of 23°C±2°C and 50% RH±5% RH. The tensile modulus of the resin film 7 for thrust bearings can be evaluated in MD and TD. The tensile modulus can be measured in accordance with JIS K7127. The tensile modulus of the resin film 7 for thrust bearings is preferably 2000 MPa or more and 5000 MPa or less, more preferably 2250 MPa or more and 4500 MPa or less, more preferably 2500 MPa or more and 4000 MPa or less, and even more preferably 2700 MPa or more and 3750 MPa or less.

[0089] This is because, if the tensile modulus of the resin film 7 for thrust bearings is less than 2000 MPa, the rigidity of the backing plate of the thrust bearing 6 decreases, causing deformation such as dents and distortion in the resin film 7 for thrust bearings due to the weight of the rotating shaft 2. On the other hand, if the tensile modulus of the resin film 7 for thrust bearings exceeds 5000 MPa, it takes time and effort to process the backing plate from the resin film 7 for thrust bearings, resulting in increased processing costs.

[0090] The toughness of the resin film 7 for thrust bearings can be evaluated by the maximum tensile strength and tensile elongation at break in an environment of 23°C ± 2°C and 50% RH ± 5% RH. The maximum tensile strength and tensile elongation at break of the resin film 7 for thrust bearings can be evaluated in MD and TD. The maximum tensile strength and tensile elongation at break can be measured in accordance with JIS K7127.

[0091] The maximum tensile strength of the resin film 7 for thrust bearings at 23°C is 50 MPa or more, preferably 50 MPa to 350 MPa, more preferably 70 MPa to 300 MPa, even more preferably 85 MPa to 200 MPa, and most preferably 85 MPa to 150 MPa. If the maximum tensile strength of the resin film 7 for thrust bearings is less than 50 MPa, the resin film 7 for thrust bearings has low mechanical strength during molding, and is therefore prone to breakage, cracking, and tearing, making molding difficult. On the other hand, if the maximum tensile strength exceeds 350 MPa, the melt viscosity of the molding material 9 is high, which places an excessive load on the melt extrusion molding machine 10, making it difficult to mold a good resin film by melt extrusion molding.

[0092] The tensile elongation at break of the resin film 7 for thrust bearings at 23° C. is optimally 90% or more, preferably 90% or more and 500% or less, more preferably 90% or more and 350% or less, and even more preferably 90% or more and 300% or less. This is because if the maximum tensile strength of the resin film 7 for thrust bearings is less than 50 MPa and the elongation at break is less than 90%, the resin film 7 for thrust bearings does not have sufficient toughness, and problems such as breakage, cracking, and tearing will occur when the resin film 7 for thrust bearings is used as a backing plate for the thrust bearing 6.

[0093] The surface roughness of the resin film 7 for thrust bearings can be evaluated by the arithmetic mean roughness in an environment of 23°C±2°C and 50% RH±5% RH. This arithmetic mean roughness can be evaluated in MD and TD in accordance with JIS B0601-2001. The arithmetic mean roughness is optimally in the range of 0.010 μm or more and 2.0 μm or less, preferably 0.015 μm or more and 1.80 μm or less, more preferably 0.017 μm or more and 1.60 μm or less, and even more preferably 0.020 μm or more and 1.35 μm or less.

[0094] This is because if the arithmetic mean roughness is less than 0.010 μm, sufficient sliding properties cannot be obtained, and if the arithmetic mean roughness exceeds 2.0 μm, the wear resistance decreases, which causes problems in long-term use when used as a backing plate for thrust bearing 6.

[0095] The heat resistance of the resin film 7 for thrust bearings can be expressed by the storage modulus at 250° C. by a dynamic viscoelastic method. From the viewpoint of obtaining excellent heat resistance, the heat resistance of the resin film 7 for thrust bearings is such that the storage modulus at 250° C. is 1.0×10 in both MD and TD when measured under conditions of a frequency of 1 Hz and a temperature rise rate of 3° C. / min. 7 Pa or more, preferably 1.0×10 7 Pa or more 1.0×10 10 Pa or less, more preferably 7.5×10 7 Pa or more 1.0×10 10 Pa or less, more preferably 1.0×10 8 Pa or more 1.0×10 10 It is better if it is less than Pa.

[0096] This is because the storage modulus at 250°C is 1.0×10 7 If it is less than Pa, sufficient heat resistance cannot be obtained due to frictional heat caused by friction, and deformation such as dents and distortion occurs in the resin film 7 for thrust bearing of the thrust bearing 6.

[0097] According to the above, since the molding material 9 of the resin film 7 for thrust bearings is polyether ether ketone resin, excellent wear resistance and heat resistance can be obtained. Therefore, even if the motor 1 is required to have high speed rotation exceeding 10,000 rpm, the resin film 7 for thrust bearings can be prevented from being deformed or cracked due to frictional heat generated when the rotating shaft 2 of the motor 1 and the resin film 7 for thrust bearings are in sliding contact with each other.

[0098] Furthermore, since the crystallinity, thermal dimensional change rate, taper wear amount, static friction coefficient, dynamic friction coefficient, maximum tensile strength, and tensile elongation at break of the resin film 7 for thrust bearings are numerically limited, it is possible to adequately support the load of the rotating shaft 2 of the motor 1 and prevent the occurrence of dents or the like in the thrust bearing 6. Furthermore, since there is no need to perform a long heat treatment after molding to improve heat resistance, the thrust bearing 6 can be manufactured cheaply in a short time.

[0099] In the above embodiment, a plurality of herringbone grooves 4 are arranged on the circumferential surface of the rotating shaft 2, but a plurality of herringbone grooves 4 may be arranged on the inner diameter surface of the radial bearing 5, and the lubricant 8 may be collected in the herringbone grooves 4 to generate dynamic pressure to support the rotating shaft 2 with high precision. Also, screw-shaped grooves other than the herringbone grooves 4 may be arranged, and the herringbone grooves 4 may be omitted if not particularly required. In the above embodiment, the molten polyether ether ketone resin is pressed against the cooling roll 18 by the pressure roll 17 to be in close contact with the cooling roll 18, but the present invention is not limited to this. For example, the molten band-shaped polyether ether ketone resin may be in close contact with the cooling roll 18 by using an electrostatic application method (or pinning method) or an air knife.

[0100] In addition, when cooling the molten polyetheretherketone resin, a method of closely contacting the molten strip-shaped polyetheretherketone resin with a metal belt or the like, spraying water onto the molten strip-shaped polyetheretherketone resin, or pouring the molten strip-shaped polyetheretherketone resin into water, etc. may be adopted. In addition, at least one of the front and back surfaces of the resin film 7 for thrust bearings can be subjected to a surface activation treatment such as a corona treatment, a plasma treatment such as a vacuum plasma treatment or an atmospheric plasma treatment, an ultraviolet treatment, or an Itro treatment.

[0101] In addition, various properties can be added to the resin film 7 for thrust bearings by printing, various functional coatings, lamination, etc., to further improve its value. It is also possible to manufacture a resin film 7 for thrust bearings having a three-layer structure by dividing the melt extruder 10 into a first, second, and third melt extruder 10. The backing plate of the thrust bearing 6 may be the resin film 7 for thrust bearings alone, or may have a multilayer structure with the resin film for thrust bearings, or may have a multilayer structure with other resin sheets other than the resin film for thrust bearings. Furthermore, all of the technologies described in this specification are subject to the acquisition of rights through amendments, divisional applications, etc. EXAMPLES

[0102] EXAMPLES Hereinafter, examples of a resin film for a thrust bearing according to the present invention and a method for producing the same will be described together with comparative examples. Example 1 First, to manufacture a resin film for thrust bearings, a commercially available polyether ether ketone resin (manufactured by Solvay Spessarty Polymers Japan, product name KetaSpire PEEK KT-851NL SP (hereinafter abbreviated as "KT-851NL SP")) was prepared and placed in a dehumidifying dryer heated to 160°C and dried for more than 12 hours.

[0103] Next, the polyether ether ketone resin was set in a single-screw extruder equipped with a T-die as shown in Figure 2 and melt-kneaded. This melt-kneaded polyether ether ketone resin was continuously extruded from the T-die of the single-screw extruder and cooled by being sandwiched between multiple pressure rolls and a cooling roll having fine irregularities on its peripheral surface, thereby extruding a resin film for thrust bearings with a thickness of 100 μm into a strip shape.

[0104] At this time, the temperature of the single screw extruder was adjusted to 380 to 400°C, the temperature of the T-die to 400°C, and the temperature of the connecting pipe connecting these single screw extruders and the T-die to 400°C. When the polyether ether ketone resin was charged into the single screw extruder, nitrogen gas was supplied at 18 L / min through an inert gas supply pipe. The temperature of the molten polyether ether ketone resin was measured by measuring the resin temperature at the inlet of the T-die, and was found to be 397°C.

[0105] After the resin film for thrust bearings was extrusion-molded, both sides of the continuous resin film for thrust bearings were cut with a slit blade and sequentially wound around a winding tube of a winder to produce the resin film for thrust bearings. At this time, the resin film for thrust bearings was sequentially wound around a pair of pressure rolls made of silicone rubber at 210°C, multiple cooling rolls at 210°C, and a 6-inch winding tube located downstream of these, as shown in Figure 2.

[0106] The Tg and Tm of KT-851NL SP were measured using a differential scanning calorimeter (manufactured by SII Nanotechnologies, product name: High-sensitivity differential scanning calorimeter X-DSC7000) at a heating rate of 10°C / min in accordance with JIS K7121. The Tg and Tm of KT-851NL SP were 146°C and Tm was 340°C. The Tg and Tm of the resin film for thrust bearings were measured using a differential scanning calorimeter (manufactured by SII Nanotechnologies, product name: High-sensitivity differential scanning calorimeter X-DSC7000) at a heating rate of 10°C / min in accordance with JIS K7121. The Tg and Tm of the resin film for thrust bearings were measured using a differential scanning calorimeter (manufactured by SII Nanotechnologies, product name: High-sensitivity differential scanning calorimeter X-DSC7000) at a heating rate of 10°C / min in accordance with JIS K7121. The Tg and Tm of the resin film for thrust bearings were measured at a heating rate of 145°C and Tm was 336°C.

[0107] The apparent shear viscosity of the polyether ether ketone resin was measured using a twin capillary rheometer R6000 (product name, manufactured by IMATEK Co., Ltd.) after drying the polyether ether ketone resin at 160° C. for 12 hours. Specifically, 40 g of polyether ether ketone resin was put into the barrel at a capillary die: φ1.0 mm×16 mm (long die), φ1.0 mm×0.25 mm (short die), barrel diameter: 15 mm, temperature: 375° C., and the piston was pushed in at a speed of 50 mm / min until the pressure reached 0.9 MPa on the long die side and 0.3 MPa on the short die side, and when the pressure reached a predetermined value, the state was maintained for 6 minutes.

[0108] After that, the piston is pushed again at a speed of 50 mm / min until the pressure becomes 0.9 MPa on the long die side and 0.3 MPa on the short die side. When the pressure reaches the specified value, the piston is pushed at a specified apparent shear rate (10, 20, 30, 50, 80, 100, 200, 300, 800 sec -1 ) was applied and measured to obtain the apparent shear viscosity. -1 The apparent shear viscosity of KT-851NL SP at is 1.00×10 3 It was Pa·s.

[0109] Once the resin film for thrust bearings was produced, the thickness, crystallinity, thermal dimensional stability, wear characteristics, sliding properties, rigidity, toughness, surface roughness, and heat resistance of this resin film for thrust bearings were evaluated and the results are summarized in Table 1. Thermal dimensional stability was evaluated by the rate of thermal dimensional change, wear characteristics by the taper wear amount, sliding characteristics by the dynamic friction coefficient and static friction coefficient, rigidity by the tensile modulus, toughness by the maximum tensile strength and tensile elongation at break, surface roughness by the arithmetic mean roughness, and heat resistance by the storage modulus at 250°C.

[0110] Thickness of resin film for thrust bearings The thickness of the resin film for thrust bearings was measured using a micrometer (Mitutoyo Corporation, product name: Coolant Proof Micrometer, code MDC-25PJ). Measurements were taken at 10 random locations in the MD of the resin film for thrust bearings, and the average value was taken as the film thickness.

[0111] ·Crystallization of resin film for thrust bearings The degree of crystallinity of the resin film for thrust bearings was measured by weighing out about 8 mg of a measurement sample from the resin film for thrust bearings and using a differential scanning calorimeter (manufactured by SII Nanotechnologies, product name: EXSTAR7000 series X-DSC7000) at a heating rate of 10°C / min over a measurement temperature range of 20°C to 380°C. The heat quantity (J / g) of the crystal melting peak and the heat quantity (J / g) of the recrystallization peak obtained at this time were used to calculate the degree of crystallinity using the following formula.

[0112] Crystallinity (%)={(ΔHm-ΔHc) / ΔHx}×100…(Formula 1) Where, ΔHm: Heat of crystal melting peak of resin film for thrust bearing (J / g) ΔHc: Heat quantity at the recrystallization peak of the resin film for thrust bearings (J / g) ΔHx: Theoretical value of melting energy of 100% crystallized PEEK resin, It is 130J / g.

[0113] ·Heated dimensional stability of resin film for thrust bearings The thermal dimensional stability of the resin film for thrust bearings was evaluated by the rate of thermal dimensional change. When measuring this rate of thermal dimensional change, first, in accordance with JIS K7133, a test piece was used in which the resin film for thrust bearings was cut to a size of MD: 120 mm × TD: 120 mm, and 100 mm marks were drawn on the MD and TD of the test piece, and the length between the marks was measured with a vernier caliper. Then, the test piece was placed in an oven at 200 ° C. and 250 ° C. and heated for 10 minutes each. After heating for 10 minutes in this way, the test piece was naturally cooled to 23 ° C., and the length between the marks was measured again at 23 ° C. ± 2, 50 ± 5% RH, and the rate of thermal dimensional change was calculated by the following formula.

[0114] Heat dimensional change rate (%) = {(L-L0) / L0} x 100 Where, L0: Gauge length before test (mm) L: Gauge distance after heating (mm)

[0115] ·Wear properties of resin film for thrust bearings The wear characteristics of the resin film for thrust bearings were evaluated by the amount of taper wear, which was measured in an environment of 23°C ± 2°C temperature, 50% RH ± 5% RH relative humidity, in accordance with JIS K7204, with an abrasive wheel of H22, a load of 1 kg, 1000 revolutions, and a rotation speed of 60 rpm.

[0116] -Sliding properties of resin film for thrust bearings The sliding properties of the resin film for thrust bearings were evaluated by measuring the static and dynamic friction coefficients. The static and dynamic friction coefficients were measured in accordance with JIS K7125. Specifically, a surface property measuring instrument (manufactured by Shinto Scientific, product name: HEDON-14) was used, and measurements were performed under the conditions of 23°C ± 2°C, 50% RH ± 5% RH, test speed: 100 mm / min, load: 200 g, and contact area: 63.5 mm x 63.5 mm. The resin film for thrust bearings was fixed to the moving table, and a ball indenter with a diameter of 10 mm was fixed to the fixed table, and a load of 200 g was applied to measure the static and dynamic friction coefficients at a speed of 100 mm / min.

[0117] · Stiffness of resin film for thrust bearings The rigidity of the resin film for thrust bearings was evaluated by its tensile modulus at 23°C. The tensile modulus was measured in both the MD and TD. The measurement was performed in accordance with JIS K7127, using test piece 1B, a tensile speed of 50 mm / min, a temperature of 23°C±2°C, and a relative humidity of 50%±5%.

[0118] ·Toughness of resin film for thrust bearings The toughness of the resin film for thrust bearings was evaluated by its maximum tensile strength and tensile elongation at break at 23°C. These maximum tensile strength and tensile elongation at break were measured in the MD and TD. The measurements were performed in accordance with JIS K7127, using test piece 1B, a tensile speed of 50 mm / min, at a temperature of 23°C±2°C, and a relative humidity of 50%±5%.

[0119] Surface roughness of resin film for thrust bearings The surface roughness of the resin film for thrust bearings was evaluated by the arithmetic mean roughness. This surface roughness was measured under an environment of 23°C ± 2°C and relative humidity of 50% RH ± 5% RH. Specifically, in accordance with JIS B0601-2001, the cooling roll side of the resin film for thrust bearings was measured in the MD and TD at a speed of 0.6 mm / s.

[0120] -Heat resistance of resin film for thrust bearings The heat resistance of the resin film for thrust bearings was evaluated by the storage modulus (E') of the resin film for thrust bearings at 250° C. This storage modulus was measured in the MD and TD of the resin film for thrust bearings by a dynamic viscoelastic method.

[0121] Specifically, when measuring the storage modulus in MD of the resin film for thrust bearings, the film was cut to a size of MD: 60 mm × TD: 6 mm, and when measuring the storage modulus in TD, the film was cut to a size of MD: 6 mm × TD: 60 mm. The storage modulus was measured in tension mode using a viscoelasticity spectrometer (TS Instruments Japan, product name: RSA-G2) under the conditions of a frequency of 1 Hz, strain of 0.1%, heating rate of 3°C / min, measurement temperature range of -60 to 360°C, and check distance of 21 mm, and the storage modulus at 250°C was obtained.

[0122] Example 2 This example was basically the same as Example 1, but the thickness of the resin film for thrust bearings was changed to 150 μm. After the resin film for thrust bearings was produced, the crystallinity, heated dimensional stability, wear characteristics, sliding properties, rigidity, toughness, surface roughness, and heat resistance of this resin film for thrust bearings were evaluated and summarized in Table 1. The Tg and Tm of this resin film for thrust bearings were measured by the same method as in Example 1, and were found to be 148° C. and 337° C.

[0123] Example 3 This example was basically the same as Example 1, except that the thickness of the resin film for thrust bearings was changed to 250 μm. After the resin film for thrust bearings was produced, the crystallinity, heated dimensional stability, wear characteristics, sliding properties, rigidity, toughness, surface roughness, and heat resistance of this resin film for thrust bearings were evaluated and summarized in Table 1. The Tg and Tm of this resin film for thrust bearings were measured by the same method as in Example 1, and were found to be 148° C. and 338° C.

[0124] Example 4 First, as a commercially available PEEK resin, KT-851NL SP in Example 1 was changed to Victrex Granules 450G (product name of Victrex Co., Ltd.; hereinafter abbreviated as "450G"). The Tg and Tm of this 450G were measured by the same method as in Example 1, and found to be 143°C and 347°C. In addition, a silicone rubber roll was used as the pressure roll in Examples 1 to 3, but a metal elastic roll with a smooth surface was used as the pressure roll in Example 4. A cooling roll having fine irregularities on the surface of the roll was used in Examples 1 to 3, but a cooling roll with a mirror surface was used in Example 4.

[0125] A resin film for thrust bearings was produced in the same manner as in Example 1, and the apparent shear viscosity at 450 G and 375°C was measured in the same manner as in Example 1. The apparent shear viscosity at 450 G and 375°C was 100 s -1 The apparent shear viscosity at 450 G is 1.32 × 10 3In addition, when manufacturing the resin film for thrust bearings, the thickness of the resin film for thrust bearings was changed to 250 μm.

[0126] After the resin film for thrust bearings was produced, the crystallinity, heated dimensional stability, wear characteristics, sliding properties, rigidity, toughness, surface roughness, and heat resistance of this resin film for thrust bearings were evaluated by the same methods as in Example 1, and the results are summarized in Table 1. The Tg and Tm of this resin film for thrust bearings were measured by the same method as in Example 1, and were found to be 146°C and 341°C.

[0127] Example 5 This example was basically the same as Example 1, except that the thickness of the resin film for thrust bearings was changed to 500 μm. After the resin film for thrust bearings was produced, the crystallinity, heated dimensional stability, wear characteristics, sliding properties, rigidity, toughness, surface roughness, and heat resistance of this resin film for thrust bearings were evaluated and are listed in Table 1. The Tg and Tm of this resin film for thrust bearings were measured by the same method as in Example 1, and showed a Tg of 147° C. and a Tm of 343° C.

[0128] Example 6 The process is basically the same as in Example 1, but whereas in Example 1 the film was sandwiched between a pressure roll and a cooling roll heated to 210° C., in Example 6 the film was sandwiched between a pressure roll and a cooling roll heated to 150° C. In addition, when producing the resin film for thrust bearings, the thickness of the resin film for thrust bearings was changed to 230 μm.

[0129] After the resin film for thrust bearings was produced, the crystallinity, heated dimensional stability, wear characteristics, sliding properties, rigidity, toughness, surface roughness, and heat resistance of this resin film for thrust bearings were evaluated by the same methods as in Example 1, and the results are shown in Table 1. The Tg and Tm of this resin film for thrust bearings were measured by the same method as in Example 1, and the Tg and Tm were found to be 142°C and 338°C.

[0130] [Table 1]

[0131] Comparative Example 1 First, the polyether ether ketone resin used in Example 1 was used as the commercially available polyether ether ketone resin, and a resin film for a thrust bearing was produced in the same manner as in Example 1. During this production, the resin film was sandwiched between a pressure roll and a cooling roll heated to 210°C in Example 1, but in this Comparative Example 1, the resin film was sandwiched between a pressure roll and a cooling roll heated to 150°C.

[0132] Next, the resin film for thrust bearings was simultaneously biaxially stretched using a commercially available simultaneous biaxial stretching machine that simultaneously stretches in the extrusion direction (also called the longitudinal direction) and the width direction (also called the transverse direction). Specifically, the resin film for thrust bearings was simultaneously biaxially stretched 1.5 times in the extrusion direction and 1.5 times in the width direction using a tenter system. At this time, the temperature of the preheating part of the heating furnace of the simultaneous biaxial stretching machine was heated at 90°C for 30 seconds, and then stretched 1.5 times in the extrusion direction and 1.5 times in the width direction while heating at 155°C for 120 seconds. Both sides of the biaxially stretched resin film for thrust bearings thus obtained were cut with a slit blade and sequentially wound around a winding tube of a winding machine to produce a resin film for thrust bearings having a thickness of 220 μm.

[0133] After the resin film for thrust bearings was produced, the crystallinity, heated dimensional stability, wear characteristics, sliding properties, rigidity, toughness, surface roughness, and heat resistance of this resin film for thrust bearings were evaluated by the same methods as in Example 1, and the results are summarized in Table 2. The Tg and Tm of this resin film for thrust bearings were measured by the same method as in Example 1, and were found to be 144°C and 343°C.

[0134] Comparative Example 2 Polyether ether ketone resin was changed to non-crystalline thermoplastic polyimide resin, and this non-crystalline thermoplastic polyimide resin was used as the molding material to manufacture a resin film for thrust bearings. A commercially available polyetherimide resin (manufactured by Sabic Corporation: product name ULTEM CRS5001-1000-NB (hereinafter abbreviated as "CRS5001")) was selected as the non-crystalline thermoplastic polyimide resin. This CRS5001 was placed in a dehumidified hot air dryer heated to 160°C and dried for 12 hours. CRS5001 is a polycondensation product of 4,4'-[isopropylidenebis(p-phenyleneoxy)diphthalic dianhydride] and p-phenylenediamine.

[0135] Thereafter, a resin film for thrust bearings was extrusion-molded in the same manner as in Example 1, and both sides of this resin film for thrust bearings were cut with a slit blade and sequentially wound around a winding tube of a winder to produce a resin film for thrust bearings with a thickness of 200 μm. During production, the apparent melt viscosity of CRS5001 at 370°C was measured in the same manner as in Example 1, and the apparent melt viscosity of CRS5001 was 977 Pa s. In addition, the Tg of CRS5001 was measured in the same manner as in Example 1, and the Tg of CRS5001 was 222°C.

[0136] After the resin film for thrust bearings was produced, the crystallinity, heated dimensional stability, wear characteristics, sliding properties, rigidity, toughness, surface roughness, and heat resistance of this resin film for thrust bearings were evaluated by the same methods as in Example 1, and the results are summarized in Table 2. The Tg of this resin film for thrust bearings was measured by the same method as in Example 1, and was found to be 222°C.

[0137] [Table 2]

[0138] [Results] In each example, the thermal dimensional change rate of the resin film for thrust bearings at 200°C and 250°C was -5% or more and 5% or more in both MD and TD, and the resin film had good thermal dimensional stability. In addition, the taper wear amount of the resin film for thrust bearings at 23°C was 3.9 mg or more and 10 mg or less, and excellent wear resistance was ensured. The static friction coefficient of the resin film for thrust bearings was 0.5 or less in both MD and TD, and the dynamic friction coefficient was 0.25 or less in both MD and TD, confirming excellent sliding properties.

[0139] In each example, the resin film for thrust bearings had a tensile modulus of 2700 MPa or more and 3800 MPa or less, and thus had sufficient rigidity. In addition, the maximum tensile strength was 90 MPa or more, and the tensile elongation at break was 180% or more, and thus had sufficient toughness. Furthermore, the storage modulus of the resin film for thrust bearings at 250°C was 1.32 × 10 in both MD and TD. 8 Pa or more, and no deterioration in heat resistance was observed in the resin film for thrust bearings.

[0140] In contrast, in the case of Comparative Example 1, since the resin film for thrust bearings was biaxially stretched, there were no problems with wear characteristics, rigidity, toughness, and heat resistance, but the thermal dimensional change rate was very large at over -8.71%. In addition, since the TD dynamic friction coefficient was 0.40 or more, problems arose with the sliding properties, and it was found that the resin film is not suitable for thrust bearings.

[0141] In the case of Comparative Example 2, the resin film for thrust bearings had no problems with the thermal dimensional stability, sliding properties, and rigidity, but the taper wear amount was 84.7 mg, indicating that the wear properties were extremely poor, and it was found that the film was not suitable as a resin film for thrust bearings. In addition, the tensile elongation at break in TD was 30% or less, indicating a serious problem with toughness. Furthermore, the storage modulus at 250°C was 1.0×10 in both MD and TD. 7 The thermal resistance was insufficient. [Industrial Applicability]

[0142] The resin film for thrust bearings and the manufacturing method thereof according to the present invention are used in the fields of information equipment, office equipment, multimedia equipment, home appliances, air conditioners, and the like. [Explanation of symbols]

[0143] 1 Motor (actuator) 2 Rotation Axis 3 Lower end (end) 4 Herringbone groove (groove) 5 Radial bearings 6 Thrust bearing 7 Resin film for thrust bearings 8. Lubricants 9 Molding material 10 Melt extrusion machine 14 Dice 17 Pressure Roll 18 Cooling roll

Claims

1. A resin film for a thrust bearing that slidably supports an end of a rotating shaft of an actuator, A resin film for thrust bearings, which is extrusion molded from a molding material containing at least a crystalline polyether ether ketone resin, has a crystallinity of 7.0% or more and 35.0% or less, a thermal dimensional change rate in the extrusion direction and in the width direction perpendicular to the extrusion direction at 200°C and 250°C is -7.9% or more and 5.0% or less when measured in accordance with JIS K7133, and a taper wear amount at 23°C is 3.9 mg or more and 20.0 mg or less when measured in accordance with JIS K7204.

2. 2. The resin film for thrust bearings according to claim 1, wherein the static friction coefficient and the dynamic friction coefficient at 23° C. are 0.05 to 0.50 and 0.05 to 0.38, respectively, when measured in accordance with JIS K7125.

3. 3. The resin film for thrust bearings according to claim 1 or 2, which has a maximum tensile strength at 23°C of 50 MPa or more when measured in accordance with JIS K7127, and a tensile elongation at break at 23°C of 90% or more when measured in accordance with JIS K7127.

4. 3. The resin film for thrust bearing according to claim 1 or 2, wherein the actuator comprises a motor, the rotating shaft of the motor is supported by a radial bearing via a lubricant, a groove is cut circumferentially into either the peripheral surface of the rotating shaft or the inner diameter surface of the radial bearing, and an end of the rotating shaft protruding from the radial bearing is supported so as to be in sliding contact with the thrust bearing.

5. 3. A method for producing a resin film for thrust bearings according to claim 1 or 2, characterized in that a molding material containing a crystalline polyether ether ketone resin having a crystallinity of at least 7.0% or more and 35.0% or less is melt-kneaded, the molding material is extruded from a die into a roughly strip shape, and the extruded molding material is brought into contact with a cooling roll to form a resin film for thrust bearings.

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