JP4907105B2 - Hydrodynamic bearing device housing and fluid bearing device housing and bearing sleeve integrated member - Google Patents

Description

The present invention relates to a housing for a hydrodynamic bearing device, and an integrated member of the housing for a hydrodynamic bearing device and a bearing sleeve . The bearing device having the housing or the integrated member includes information devices such as magnetic disk drive devices such as HDD, optical disk drive devices such as CD-ROM, CD-R / RW, DVD-ROM / RAM, MD, MO, etc. It is suitable for a spindle motor such as a magneto-optical disk driving device, a polygon scanner motor of a laser beam printer (LBP), a color wheel of a projector, or a small motor such as an electric device such as an axial fan.

  In addition to high rotational accuracy, the various motors are required to have high speed, low cost, low noise, and the like. One of the components that determine the required performance is a bearing that supports the spindle of the motor. In recent years, the use of a fluid bearing having characteristics excellent in the required performance has been studied or actually used. .

  This type of hydrodynamic bearing includes a hydrodynamic bearing having a dynamic pressure generating portion for generating a dynamic pressure in the lubricating fluid in the bearing gap, and a so-called true circular bearing having no dynamic pressure generating portion (with a bearing cross section). It is roughly divided into a perfect circle bearing).

  For example, in a hydrodynamic bearing device incorporated in a spindle motor of a disk drive device such as an HDD, both a radial bearing portion that supports a shaft member constituting a rotating member in a radial direction and a thrust bearing portion that supports a thrust direction in a thrust direction are hydrodynamic bearings. It may be configured with. As a radial bearing portion in this type of hydrodynamic bearing device (dynamic pressure bearing device), for example, either the inner peripheral surface of the bearing sleeve or the outer peripheral surface of the shaft member facing the bearing sleeve is used as a dynamic pressure generating portion. It is known that a dynamic pressure groove is formed and a radial bearing gap is formed between both surfaces (see, for example, Patent Document 1).

  The hydrodynamic bearing device is composed of parts such as a housing, a bearing sleeve, and a shaft member. In order to ensure the high rotational performance required as information equipment becomes more and more sophisticated, the dimensional accuracy and assembly of each part are ensured. Efforts are being made to improve accuracy. On the other hand, along with the trend of lowering the price of information equipment, the demand for cost reduction for this type of hydrodynamic bearing device has become increasingly severe. In response to these demands, recently, it has been studied to mold a housing, which is a component of the hydrodynamic bearing device, with a resin material (see, for example, Patent Document 2).

  On the other hand, when this type of hydrodynamic bearing device is used by being incorporated in a spindle motor for a magnetic disk device such as an HDD, the hydrodynamic bearing device is usually mounted on the motor outer surface of the motor bracket. It is performed by bonding and fixing to the peripheral surface with an adhesive. However, when the housing is formed of a material with poor adhesion, such as a resin, the adhesive surface may be peeled off due to an impact caused by a drop of an information device incorporating the magnetic disk device, which may cause a deterioration in the function of the bearing device and hence the magnetic disk device. There is. Particularly recently, in response to a request for an increase in disk capacity, the number of magnetic disks incorporated in the disk device tends to increase, and as a result, the impact force at the time of dropping further increases. A higher adhesive force is required between the bracket and the bracket.

  As a means for improving the adhesion of the resin, for example, a method of blending a monoepoxy compound with a polyphenylene sulfide (PPS) resin (see, for example, Patent Document 3), or a PPS resin modified with an epoxy group is not modified. A method of blending with other PPS resins (see, for example, Patent Document 4) is known.

However, when the housing is formed of the resin obtained by the above-described method, the following problems may occur. For example, in the former method (containing a monoepoxy compound), it is necessary to add a considerable amount in order to increase the affinity between the resin and the adhesive, and this reduces the fluidity (melt viscosity) of the entire resin. This may adversely affect the moldability of the housing. Further, in the latter method (containing epoxy-modified PPS), the low molecular weight epoxy component remaining in the epoxy-modified PPS is decomposed at the molding temperature of the housing to generate gas. If this gas remains in the molding die, a defect such as remaining as a hole in the housing or staying on the outer surface of the housing may occur, which may reduce the molding accuracy of the housing. Further, in order to obtain this kind of epoxy-modified resin, it is necessary to go through complicated and numerous steps, which leads to an increase in the manufacturing cost. From the above, none of the above methods is an appropriate means for improving the adhesive force of the housing for a hydrodynamic bearing device.
JP 2003-239951 A JP 2003-314534 A JP-A-1-65171 JP-A-8-85759

  The subject of this invention is providing the housing which improved adhesiveness with another member in this kind of hydrodynamic bearing apparatus at low cost.

In order to solve the above problems, the present invention is a fluid in which a bearing sleeve that forms a radial bearing gap between the inner periphery and the outer peripheral surface of the shaft can be fixed , and an adhesive fixing surface with another member is formed on the outer periphery. A housing for a bearing device, wherein the housing is formed of a resin composition using polyphenylene sulfide (PPS) as a base resin, and the resin composition includes a base resin, a polyolefin as a main chain, and glycidyl methacrylate (GMA). Is a bisphenol A type epoxy compound grafted as a side chain, having two or more epoxy groups in the molecule, and an epoxy index of 0.5 meq / g or more and 4.65 meq / g or less A compound is compounded, and the amount of epoxy groups in the resin composition is 8 meq / 100 g or more and 20 meq / 10. Provided is a hydrodynamic bearing device housing characterized in that the amount of the epoxy compound in the resin composition is 0 g or less, and the proportion of the epoxy compound in the resin composition is 20 vol% or less. Alternatively, a housing for a hydrodynamic bearing device in which a housing having an adhesive fixing surface with another member on the outer periphery and a bearing sleeve that is accommodated on the inner periphery of the housing and forms a radial bearing gap between the outer periphery of the shaft are integrated. And a bearing sleeve, which are formed of a resin composition using polyphenylene sulfide (PPS) as a base resin. The resin composition includes a base resin, polyolefin as a main chain, and glycidyl methacrylate (GMA). An epoxy compound grafted as a side chain or a bisphenol A type epoxy compound having two or more epoxy groups in the molecule and having an epoxy index of 0.5 meq / g or more and 4.65 meq / g or less The amount of epoxy groups in the resin composition is 8 meq / 100 g or more and 20 Provided is an integral member of a housing for a hydrodynamic bearing device and a bearing sleeve, wherein the meq / 100 g or less and the blending ratio of the epoxy compound in the resin composition is 20 vol% or less.

  In the present invention, compounding an epoxy group-containing compound (epoxy compound) with the base resin is effective for improving the adhesion, and among the epoxy compounds, an epoxy having two or more epoxy groups in the molecule. It was created based on the knowledge of the present inventors that the adhesiveness is remarkably improved by blending a compound. In addition, the present invention is based on the following knowledge, and by specifying the type of epoxy compound to be blended and the blending amount thereof, the adhesiveness and moldability of the housing are compatible at a high level and at a low cost. is there.

  That is, by blending the epoxy compound such that the amount of epoxy groups in the resin composition (the density of epoxy functional groups) is 8 meq / 100 g or more, the affinity between the housing and the adhesive formed by the resin composition Property (adhesiveness) can be improved. Thereby, the adhesive strength with other members (motor bracket etc.) used as an adhesion partner material can be improved, and the demand for increasing the disk capacity of the disk device can be met. At the same time, in the present invention, an epoxy compound having an epoxy index of 0.5 meq / g or more was selected as the epoxy compound to be blended in the resin composition. According to such a compound, the blending ratio of the epoxy compound to the polyphenylene sulfide (PPS) in the resin composition can be suppressed, in other words, the blending ratio of the polyphenylene sulfide (PPS) can be set as high as possible. Therefore, it is possible to increase the adhesiveness with other members (such as a motor bracket) at low cost while ensuring high fluidity (moldability) during molding of the resin composition.

  In the present invention, the polyphenylene sulfide (PPS) used as the base resin for the housing is a crystalline resin having a high crystallinity, and therefore, the interaction between the molecular chains is strong, and the low viscosity ester-based lubricating oil. Is difficult to penetrate into the resin. Therefore, if the housing is formed of a resin material based on these resins, high oil resistance can be imparted to the housing regardless of the type of lubricating oil. In addition, since the resin material is a resin having excellent fluidity in a molten state among crystalline resins, the moldability of the housing can be secured and the housing can be easily reduced in size. it can. Further, since the resin material has an advantage that the amount of outgas generated during solidification is small, the housing is formed of the resin material, so that the amount of outgas generated at the time of molding the housing or after molding is suppressed, and the bearing device or the disk device. The cleanliness of can be kept at a high level.

  The amount of epoxy groups in the resin composition is preferably 20 meq / 100 g or less. By suppressing the amount of epoxy groups in the resin composition within the above range, for example, by suppressing the amount of gas generated during injection molding, the dimensional defect of the molded product due to a large amount of gas remaining in the mold And defects such as poor appearance can be resolved.

  The compounding ratio of the epoxy compound in the resin composition is preferably 20 vol% or less. By suppressing the blending ratio of the epoxy compound within the above range, the high oil resistance and good moldability (high fluidity) inherent in PPS can be sufficiently expressed. In particular, the high abrasion resistance of PPS may be reduced by increasing the blending ratio of the epoxy compound, but by suppressing the blending ratio within the above range, such problems can be eliminated and high wear resistance can be achieved. It is possible to impart the property to the housing.

  As the epoxy compound, for example, a polyolefin grafted with a main chain and glycidyl methacrylate (GMA) as a side chain or a bisphenol A type (BPA) epoxy compound can be preferably used.

  It is preferable that Na content of the resin composition containing the polyphenylene sulfide (PPS) and the epoxy compound is 2000 ppm or less. According to this, NaCl or the like, which is a byproduct of polyphenylene sulfide (PPS), is reduced, and for example, Na contained in polyphenylene sulfide (PPS) is also reduced. Therefore, the elution amount of Na ions in the lubricating oil is suppressed, and the cleanliness inside or outside the bearing can be kept at a high level. In order to suppress the Na content of polyphenylene sulfide (PPS) within the above numerical range (2000 ppm or less), for example, it may be washed using a solvent having a large relative dielectric constant (at least 10 or more). Further, by washing with acid, Na in the molecular end group can be removed, so that the Na content can be further reduced. Specifically, among polyphenylene sulfide (PPS), linear polyphenylene sulfide (PPS) having the smallest side chain is preferable in that the number of molecular end groups per unit volume is small and the Na content is small.

  A housing for a hydrodynamic bearing device is required to have high strength and impact resistance in addition to the above-mentioned required characteristics, as well as a bonded portion with other members, in accordance with recent portability of electronic equipment. Further, when a thrust bearing gap is formed between the housing and the rotating member, high dimensional stability is required from the viewpoint of managing the bearing gap with high accuracy. Therefore, in the present invention, carbon fiber is blended as a filler in a resin composition containing polyphenylene sulfide (PPS) and an epoxy compound. According to this, the strength of the housing is increased, the low thermal dimensional change property of the carbon fiber is expressed, and the dimensional change accompanying the temperature change of the resin portion is suppressed. As a result, the thrust bearing gap during use is controlled with high accuracy, and high bearing performance can be exhibited. Moreover, since carbon fiber has electroconductivity, a high electroconductivity can be given to a housing by mix | blending with a resin composition as a filler. Thereby, static electricity charged on the rotating member (for example, a disk hub) during use can be released to the grounding member via the housing.

  In order to satisfy the above required characteristics, the carbon fiber preferably has a tensile strength of 3000 MPa or more. As a material having both high strength and high electrical conductivity, for example, PAN (polyacrylonitrile) carbon fiber can be cited.

  The reinforcement effect, dimensional stability effect, electrostatic removal effect, and the like due to the blending of these carbon fibers into the resin composition are more remarkably exhibited by considering the aspect ratio of the carbon fibers. That is, the larger the fiber length of the carbon fiber, the higher the reinforcing effect and the electrostatic removal effect, and the smaller the fiber diameter, the more the wear resistance, particularly the damage of the sliding counterpart material can be suppressed. From these viewpoints, specifically, the aspect ratio of the carbon fiber is preferably 6.5 or more.

  The filling amount of the carbon fiber as the filler into the base resin is preferably 10 to 35 vol%. For example, if the filling amount is less than 10 vol%, the reinforcing effect and electrostatic removal effect due to the filling of the carbon fiber are not sufficiently exhibited, and if the filling amount exceeds 35 vol%, the moldability of the housing is ensured. This is because it becomes difficult.

The housing for a hydrodynamic bearing device having the above configuration can be suitably provided as a hydrodynamic bearing device including the housing, a bearing sleeve fixed to the inner periphery of the housing, and a rotating member having a shaft. In this case, the radial bearing gap is formed inside the housing, between the inner peripheral surface of the bearing sleeve and the outer peripheral surface of the shaft facing the bearing sleeve. Alternatively, the integrated member of the housing for a hydrodynamic bearing device and the bearing sleeve having the above configuration can be suitably provided as a hydrodynamic bearing device including the integrated member and a rotating member having a shaft. In this case, the radial bearing gap is formed directly between the outer circumferential surface of the shaft to the inner peripheral surface opposed to the integrated member of the housing and the bearing sleeve.

  The hydrodynamic bearing device includes: the hydrodynamic bearing device; a fixing member that is bonded and fixed to an adhesive fixing surface of the housing, and fixes the hydrodynamic bearing device to the inner periphery; a stator coil; and a stator coil. It can be suitably provided as a motor including a rotor magnet that generates an exciting force therebetween.

  As described above, according to the present invention, in this type of hydrodynamic bearing device, it is possible to provide a housing having high adhesiveness with other members and high moldability at low cost.

  Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 conceptually shows a configuration example of a spindle motor for information equipment incorporating a hydrodynamic bearing device 1 according to a first embodiment of the present invention. This spindle motor is used in a disk drive device such as an HDD, and is opposed to a hydrodynamic bearing device 1 that rotatably supports a rotating member 3 provided with a shaft 2 via a radial gap, for example. A stator coil 4 and a rotor magnet 5 and a motor bracket 6 are provided. The stator coil 4 is attached to the outer diameter side of the motor bracket (fixing member) 6, and the rotor magnet 5 is attached to the outer periphery of the rotating member 3. The housing 7 of the hydrodynamic bearing device 1 is fixed to the inner periphery of the motor bracket 6. Although not shown, the rotating member 3 holds one or more disk-shaped information recording media (hereinafter simply referred to as disks) such as magnetic disks. In the spindle motor configured as described above, when the stator coil 4 is energized, the rotor magnet 5 is rotated by the electromagnetic force generated between the stator coil 4 and the rotor magnet 5. The disk held by the member 3 rotates integrally with the shaft 2.

  FIG. 2 shows the hydrodynamic bearing device 1. The hydrodynamic bearing device 1 mainly includes a housing 7, a bearing sleeve 8 fixed to the housing 7, and a rotating member 3 that rotates relative to the housing 7 and the bearing sleeve 8. For convenience of explanation, in the housing 7 openings formed at both ends in the axial direction, the side sealed by the lid member 10 is the lower side, and the side opposite to the sealing side is the upper side.

  The rotating member 3 includes, for example, a hub portion 9 disposed on the opening side of the housing 7 and a shaft 2 inserted into the inner periphery of the bearing sleeve 8.

  The hub portion 9 is formed of a metal material or a resin material, and includes a disc portion 9a that covers the opening side (upper side) of the housing 7, a cylindrical portion 9b that extends downward from the outer periphery of the disc portion 9a, and a cylindrical portion. It comprises a disk mounting surface 9c and a flange 9d provided on the outer periphery of 9b. A disc (not shown) is fitted on the outer periphery of the disk portion 9a and placed on the disc mounting surface 9c. Then, the disc is held on the hub portion 9 by appropriate holding means (such as a clamper) not shown.

  In this embodiment, the shaft 2 is formed integrally with the hub portion 9 and is provided with a flange portion 2b as a separate member at the lower end thereof. The flange portion 2b is made of metal and is fixed to the shaft 2 by means such as screw connection.

  The bearing sleeve 8 can be formed of a metal material such as a copper alloy such as brass or an aluminum alloy, or can be formed of a porous body made of sintered metal. In this embodiment, a sintered metal porous body mainly composed of copper is formed in a cylindrical shape.

  A region in which a plurality of dynamic pressure grooves are arranged as a radial dynamic pressure generating portion is formed on the entire inner surface or a part of the cylindrical region of the inner peripheral surface 8 a of the bearing sleeve 8. In this embodiment, for example, as shown in FIG. 3, two regions where a plurality of dynamic pressure grooves 8a1 and 8a2 are arranged in a herringbone shape are formed apart from each other in the axial direction. In the formation region of the upper dynamic pressure groove 8a1, the dynamic pressure groove 8a1 is formed to be axially asymmetric with respect to the axial center m (the axial center of the upper and lower inclined groove regions). The axial dimension X1 of the upper region is larger than the axial dimension X2 of the lower region.

  For example, although not shown in the drawing, a region in which a plurality of dynamic pressure grooves are arranged in a spiral shape is formed on the entire lower surface 8c of the bearing sleeve 8 or a partial annular region. This dynamic pressure groove forming region is opposed to the upper end surface 2b1 of the flange portion 2b as a thrust bearing surface, and the thrust bearing of the second thrust bearing portion T2 is located between the upper end surface 2b1 and the shaft 2 (the rotating member 3). A gap is formed (see FIG. 2).

  The housing 7 is formed in a cylindrical shape with a resin material. In this embodiment, the housing 7 has a shape in which both ends in the axial direction are opened, and the other end is sealed with the lid member 10. A thrust bearing surface 7a is provided on the entire end surface (upper end surface) or a partial annular region on one end side. In this embodiment, a region in which a plurality of dynamic pressure grooves 7a1 are arranged in a spiral shape is formed on the thrust bearing surface 7a as a thrust dynamic pressure generating portion, for example, as shown in FIG. The thrust bearing surface 7a (dynamic pressure groove 7a1 formation region) faces the lower end surface 9a1 of the disk portion 9a of the hub portion 9, and a first thrust bearing described later is formed between the lower end surface 9a1 and the rotating member 3 when rotating. A thrust bearing gap of the portion T1 is formed (see FIG. 2).

  The lid member 10 that seals the other end side of the housing 7 is made of a metal material or a resin material, and is fixed to a stepped portion 7 b provided on the inner peripheral side of the other end of the housing 7. Here, the fixing means is not particularly limited, and for example, means such as adhesion (including loose adhesion, press-fit adhesion), press-fit, welding (for example, ultrasonic welding), welding (for example, laser welding), combinations of materials and requirements. It can be appropriately selected according to the assembly strength and sealing performance.

  The outer peripheral surface 8b of the bearing sleeve 8 is fixed to the inner peripheral surface 7c of the housing 7 by appropriate means such as bonding (including loose bonding and press-fitting bonding), press-fitting, and welding.

  On the outer periphery of the housing 7, a tapered seal surface 7 d that gradually increases in diameter upward is formed. The tapered seal surface 7d is an annular seal having a radial dimension gradually reduced from the sealing side (downward) to the opening side (upward) of the housing 7 between the inner peripheral surface 9b1 of the cylindrical portion 9b. A space S is formed. The seal space S communicates with the outer diameter side of the thrust bearing gap of the first thrust bearing portion T1 when the shaft 2 and the hub portion 9 are rotated.

  An adhesive fixing surface 7e is formed at the lower end of the outer periphery of the housing 7. In this embodiment, the adhesive fixing surface 7 e has a cylindrical shape with a constant diameter, and is adhesively fixed to the inner peripheral surface 6 a of the motor bracket 6. Thereby, the hydrodynamic bearing device 1 is incorporated in the motor.

  The fluid bearing device 1 is filled with lubricating oil, and the oil level of the lubricating oil is always maintained in the seal space S. Various types of lubricating oil can be used. In particular, a lubricating oil provided for a fluid dynamic bearing device for a disk drive device such as an HDD is required to have a low evaporation rate and a low viscosity. For example, dioctyl seba Ester lubricants such as Kate (DOS) and Dioctyl Azetate (DOZ) are suitable.

  The housing 7 is required to have high oil resistance (low oil absorption) with respect to the ester-based lubricating oil. In addition, it is necessary to keep the outgas generation amount and water absorption amount low during use. Furthermore, high heat resistance is also required.

  An example of a resin that satisfies the above required characteristics is polyphenylene sulfide (PPS). Polyphenylene sulfide (PPS) is suitable as a base resin for the housing 7 because it is available at a lower cost than other resins and has excellent fluidity (melt viscosity) during molding.

  By the way, polyphenylene sulfide (PPS) is generally produced by a polycondensation reaction of sodium sulfide and paradichlorobenzene, but simultaneously contains sodium chloride as a by-product. Therefore, it is necessary to wash polyphenylene sulfide (PPS) using an appropriate solvent. The solvent for washing may be any solvent having a relative dielectric constant of at least 10 or more, preferably 20 or more, more preferably 50 or more. Furthermore, considering environmental aspects, for example, water (relative dielectric constant of about 80) is preferable, and ultrapure water is particularly preferable. By washing with such a solvent, mainly Na of polyphenylene sulfide (PPS) end groups is removed, so the Na content in polyphenylene sulfide (PPS) can be reduced (for example, 2000 ppm or less), The resin material for forming the housing 7 can be used. In addition, there is an advantage that the crystallization speed is increased by removing Na of the terminal group.

  Polyphenylene sulfide (PPS) is roughly classified into cross-linked polyphenylene sulfide (PPS), semi-linear polyphenylene sulfide (PPS) with fewer side chains, and linear polyphenylene sulfide (PPS) with fewer side chains. A linear polyphenylene sulfide (PPS) having few chains is more preferable in terms of a small number of molecular end groups per molecule and a small Na content. Moreover, linear polyphenylene sulfide (PPS) is a preferable material because it is easier to clean than other types of polyphenylene sulfide (PPS), or it is not necessary to reduce the Na content by cleaning. Specifically, the Na content is 2000 ppm or less, more preferably 1000 ppm, and even more preferably 500 ppm or less corresponds to the linear polyphenylene sulfide (PPS). According to this, since the elution amount of Na ions into the lubricating oil is suppressed, Na is present on the surface of the hydrodynamic bearing device 1, the disk-shaped information recording medium held by the rotating member 3, or the disk head (not shown). Precipitation can be prevented.

  In the resin composition containing the above base resin, an epoxy compound having two or more epoxy groups in the molecule and having an epoxy index of 0.5 meq / g or more, the amount of epoxy groups in the resin composition is 8 meq / 100 g. It mix | blends so that it may become the above. As a result, the oil resistance and low outgas properties inherent to the base resin (PPS) and the high fluidity (low melt viscosity) at the time of molding are fully expressed, but the adhesion to the motor bracket 6 (adhesive strength). ) Can be obtained.

  Moreover, it is preferable that the said epoxy compound is mix | blended with base resin so that the amount of epoxy groups in a resin composition may be 20 meq / 100g or less. This is because when the amount of epoxy groups in the resin composition exceeds the above range (20 meq / 100 g), a non-negligible amount of gas is generated from the resin composition when the housing 7 is molded, and this gas is generated in the mold. This is because there is a risk of causing problems such as defective dimensions and poor appearance of the housing 7 as a molded product.

  From the viewpoint of suppressing gas generation during the molding, in this embodiment, when polyphenylene sulfide (PPS) is used as the base resin, polyphenylene sulfide (epoxy-unmodified PPS) not modified with an epoxy compound is used. Is preferred. The reason for this is that when epoxy-modified PPS is used as the base resin, the low-molecular-weight epoxy component remaining in the epoxy-modified PPS decomposes at the molding temperature of the housing 7 (here, the injection temperature of the epoxy-modified PPS), Generate gas. This gas remains in the mold so that it remains as a hole in the housing 7 or stays on the outer surface of the housing 7, thereby possibly reducing the molding accuracy of the housing 7.

  As the epoxy compound, any epoxy compound having an epoxy index within the above range can be used. Among them, an epoxy compound grafted with polyolefin as a main chain and glycidyl methacrylate (GMA) as a side chain, or bisphenol A Type epoxy compounds can be suitably used. In addition to the copolymer type having only glycidyl methacrylate (GMA) in the side chain, other examples of the epoxy compound exemplified above are terpolymerized by further grafting styrene or the like not containing an epoxy group in the side chain. However, as described above, using a copolymer type obtained by grafting only a compound containing an epoxy group onto a side chain is more desirable from the viewpoint of heat resistance than using a terpolymer body using styrene or the like.

  Further, the thrust bearing surface 7a provided on the upper end surface of the housing 7 generates sliding friction with the lower end surface 9a1 of the hub portion 9 facing in the axial direction when the rotating member 3 is started and stopped. The sliding wear of this type of housing 7 can be reduced by setting the compounding ratio of the epoxy compound to the base resin appropriately, specifically by setting it to 20 vol% or less.

Carbon fiber can be blended in the resin composition containing the base resin and the epoxy compound as a filler. According to this, the strength of the housing 7 can be increased, and the dimensional change accompanying the temperature change of the housing 7 can be suppressed to obtain high dimensional stability. As a result, the thrust bearing gap during use can be controlled with high accuracy. Moreover, the high electrical conductivity which carbon fiber has is expressed by mix | blending carbon fiber with base resin, and sufficient electroconductivity (for example, 1.0 * 10 < ⁶ > ohm * cm or less by volume resistance) is provided to the housing 7. Can do. As a result, static electricity charged on the disk during use can be released to the grounding side member (motor bracket 6 or the like) through the rotating member 3 and the housing 7 (also through the bearing sleeve 8).

  Various carbon fibers such as PAN and Pich can be used as the carbon fiber, but those having a relatively high tensile strength (preferably 3000 MPa or more) are preferable from the viewpoint of the reinforcing effect and shock absorption. A PAN-based carbon fiber is preferable as a material having high conductivity.

  As this PAN-based carbon fiber, one having the following size range can be used.

(1) When the molten resin is kneaded and injection-molded, the carbon fiber is cut and shortened. As fiber shortening progresses, the strength, conductivity, and the like decrease significantly, making it difficult to satisfy these required characteristics. Accordingly, as the carbon fiber to be blended in the resin, it is preferable to use a longer fiber in consideration of fiber bending at the time of molding. Specifically, carbon fiber having an average fiber length of 100 μm or more (more preferably 1 mm or more) is used. It is desirable to use it.
(2) On the other hand, in the injection molding process, the resin cured in the mold may be taken out, melted again, kneaded with the virgin resin composition, and reused (recycled). In this case, since some of the fibers are repeatedly recycled, if the initial fiber length is too long, the fiber becomes significantly shorter than the original fiber length due to cutting due to recycling, and the resin composition Changes in the properties of the product (such as a decrease in melt viscosity) become significant. In order to minimize such a characteristic change, the fiber length is preferably as short as possible. Specifically, the average fiber length is preferably 500 μm or less (preferably 300 μm or less).

  The selection of the fiber length of the carbon fiber described above can be determined depending on what history of the resin composition is used in the actual injection molding process. For example, when using only the virgin resin composition, or when using a mixture of the recycled resin composition and when the ratio of the virgin resin composition is large, from the viewpoint of suppressing a decrease in strength, conductivity, etc. It is preferable to use the carbon fiber having the dimensional range described in (1). On the contrary, when the use ratio of the recycled resin composition is large, from the viewpoint of suppressing the characteristic change of the resin composition due to recycling, the above ( It is desirable to use carbon fibers having the dimensions described in 2).

  In any of the carbon fibers of (1) and (2), the number of blends increases as the fiber diameter of the carbon fiber is thinner. Therefore, the carbon fiber is more effective for uniform product quality, and the fiber is reinforced as the aspect ratio increases. The reinforcing effect is also increased. Therefore, it is desirable that the aspect ratio of the carbon fiber is larger, and specifically, an aspect ratio of 6.5 or more is preferable. Further, the average fiber diameter is suitably 5 to 20 μm in consideration of workability and availability.

  In order to sufficiently exhibit the above-described reinforcing effect and electrostatic removal effect by the carbon fiber, the filling amount of the carbon fiber into the base resin is preferably 10 to 35 vol%, more preferably 15 to 25 vol%. This is because if the filling amount of the carbon fiber is less than 10 vol%, the reinforcing effect and electrostatic removal effect by the carbon fiber are not sufficiently exhibited, and the wear resistance of the housing 7 at the sliding portion with other members, especially the sliding This is because if the wear resistance of the counterpart material is not ensured and the filling amount exceeds 35 vol%, the moldability of the housing 7 is lowered and it is difficult to obtain high dimensional accuracy.

The melt viscosity of the resin composition in which carbon fiber is blended with the base resin and the epoxy compound is suppressed to 500 Pa · s or less at 310 ° C. and a shear rate of 1000 s ⁻¹ so that the cavity is filled with the molten resin with high accuracy. Is good. Therefore, the melt viscosity of the resin composition excluding the carbon fibers (base resin and epoxy compound) is 100 Pa · s or less at 310 ° C. and a shear rate of 1000 s ⁻¹ in order to compensate for the increase in viscosity due to the filling of the carbon fibers. It is preferable.

  Thus, if the housing 7 is formed of the above-described resin composition, high oil resistance, low outgas properties, high fluidity during molding, low water absorption, high heat resistance, and high adhesive strength with the motor bracket 6 are obtained. Thus, the durability and reliability of the hydrodynamic bearing device 1 and the disk drive device incorporating the bearing device can be improved. Furthermore, the housing 7 excellent in mechanical strength, impact resistance, moldability, dimensional stability, and electrostatic removability can be obtained by blending an appropriate amount of carbon fiber according to the application.

  In the hydrodynamic bearing device 1 having the above-described configuration, when the shaft 2 (rotating member 3) rotates, a region (a region where the dynamic pressure grooves 8a1 and 8a2 are formed in the upper and lower two locations) that becomes the radial bearing surface of the inner peripheral surface 8a of the bearing sleeve 8 It faces the outer peripheral surface 2a of the shaft 2 via a radial bearing gap. As the shaft 2 rotates, the lubricating oil in the radial bearing gap is pushed toward the axial center m of the dynamic pressure grooves 8a1 and 8a2, and the pressure rises. The dynamic pressure action of the dynamic pressure grooves 8a1 and 8a2 constitutes a first radial bearing portion R1 and a second radial bearing portion R2 that support the shaft 2 in a non-contact manner in the radial direction.

  At the same time, the thrust bearing clearance between the thrust bearing surface 7a (dynamic pressure groove 7a1 formation region) of the housing 7 and the lower end surface 9a1 of the hub portion 9 (disk portion 9a) opposite to the thrust bearing surface 7a and under the bearing sleeve 8 An oil film of lubricating oil is formed in the thrust bearing gap between the end surface 8c (dynamic pressure groove forming region) and the upper end surface 2b1 of the flange portion 2b facing the end surface 8c by the dynamic pressure action of the dynamic pressure groove. The first thrust bearing portion T1 and the second thrust bearing portion T2 that support the rotating member 3 in the thrust direction in a non-contact manner are constituted by the pressure of these oil films.

  The first embodiment of the present invention has been described above, but the present invention is not limited to this embodiment.

  In the said 1st Embodiment, although the case where an epoxy compound and carbon fiber were mix | blended with one type of base resin (polyphenylene sulfide) was demonstrated as a resin composition which forms the housing 7, unless the effect of this invention is prevented. Other crystalline resins, amorphous resins, or organic substances such as rubber components may be added, and in addition to carbon fibers, inorganic substances such as metal fibers, glass fibers, and whiskers may be added. For example, polytetrafluoroethylene (PTFE) can be blended as a release agent having excellent oil resistance, and carbon black can be blended as a conductive agent.

  In the first embodiment, a thrust bearing surface 7a in which a plurality of dynamic pressure grooves 7a1 are arranged is provided on the upper end surface of the housing 7 (thrust bearing portion T1), and a plurality of dynamic pressures are applied to the lower end surface 8c of the bearing sleeve 8. Although the case where the thrust bearing surface in which the grooves are arranged is provided (thrust bearing portion T2), the present invention can be similarly applied to a hydrodynamic bearing device provided with only the thrust bearing portion T1. In this case, the shaft 2 has a straight shape without the flange portion 2b. Therefore, the housing 7 can be formed into a bottomed cylindrical shape by integrally forming the housing 7 from the resin material with the lid member 10 as the bottom. Further, the shaft 2 and the hub portion 9 can be integrally formed of metal or resin, and the shaft 2 can be formed separately from the hub portion 9. In this case, the shaft 2 can be made of metal, and the rotating member 3 can be molded with resin integrally with the hub portion 9 using the metal shaft 2 as an insert part.

  FIG. 5 shows a hydrodynamic bearing device 11 according to the second embodiment of the present invention. In this embodiment, the shaft portion (rotating member) 12 includes a flange portion 12b provided integrally or separately at the lower end thereof. The housing 17 includes a cylindrical side portion 17a and a bottom portion 17b that is separated from the side portion 17a and is located at the lower end portion of the side portion 17a. A seal portion 13 projecting toward the inner peripheral side is formed integrally with the housing 17 at the upper end portion of the side portion 17 a of the housing 17. Although not shown in the drawing, the upper end surface 17b1 of the bottom 17b of the housing 17 is formed with, for example, a region in which a plurality of dynamic pressure grooves are arranged in a spiral shape, and the lower end surface 18c of the bearing sleeve 18 has a similar shape. A region in which the dynamic pressure grooves are arranged is formed. A first thrust bearing portion T11 is formed between the lower end surface 18c of the bearing sleeve 18 and the upper end surface 12b1 of the flange portion 12b of the shaft portion 12, and is below the upper end surface 17b1 of the bottom portion 17b of the housing 17 and the flange portion 12b. A second thrust bearing portion T12 is formed between the end surface 12b2.

  In this embodiment, the side portion 17 a of the housing 17 is formed of a resin material together with the seal portion 13. Therefore, if the same base resin and epoxy compound as those in the first embodiment are selected for the side portion 17a of the housing 17, the adhesive strength with the motor bracket (not shown), oil resistance, wear resistance, and cleanliness are included. Thus, the housing 17 having excellent dimensional stability, moldability, and the like can be obtained. Moreover, when forming the bottom part 17b with a resin material, it can also be set as the material composition similar to the side part 17a, and, thereby, the adhesive force between the housing 17 and the bottom part 17b can be improved.

  FIG. 6 shows a hydrodynamic bearing device 21 according to a third embodiment of the present invention. In this embodiment, the seal portion 23 is formed separately from the side portion 27 a of the housing 27, and is fixed to the inner periphery of the upper end portion of the housing 27 by means such as adhesion, press fitting, or welding. The bottom 27b of the housing 27 is molded with a resin material integrally with the side 27a of the housing 27, and forms a bottomed cylindrical shape. Other configurations are the same as those in the second embodiment, and thus description thereof is omitted.

  In this embodiment, the housing 27 is integrally formed of a resin material with the side portion 27a and the bottom portion 27b. Therefore, if the same base resin and epoxy compound as those in the first embodiment are selected for the housing 27, the adhesion to the motor bracket (not shown), oil resistance, wear resistance, cleanliness, dimensional stability, etc. Thus, the housing 27 excellent in moldability and the like can be obtained.

  Moreover, in the above embodiment (1st-3rd embodiment), as the radial bearing part R1, R2 and the thrust bearing part T1, T2, the dynamic pressure action of the lubricating fluid by the herringbone shape or spiral shape dynamic pressure groove However, the present invention is not limited to this.

  For example, although not shown as radial bearing portions R1 and R2, a so-called step-like dynamic pressure generating portion in which axial grooves are formed at a plurality of locations in the circumferential direction, or a plurality of circular arc surfaces in the circumferential direction. A so-called multi-arc bearing in which wedge-shaped radial gaps (bearing gaps) are formed between the outer peripheral surfaces 2a of the opposing shafts 2 (or shaft members 12, 22).

  Alternatively, the inner peripheral surface 8a of the bearing sleeve 8 serving as a radial bearing surface is a perfect circular inner peripheral surface not provided with a dynamic pressure groove or arc surface as a dynamic pressure generating portion, and the shaft 2 facing this inner peripheral surface. The so-called perfect circle bearing can be constituted by the perfect circular outer peripheral surface 2a.

  One or both of the thrust bearing portions T1 and T2 are also not shown in the figure, but a plurality of radial groove-shaped dynamic pressure grooves are provided at predetermined intervals in the circumferential direction in a region that becomes a thrust bearing surface. A step bearing or a corrugated bearing (the step mold is a corrugated one) can also be used.

  In the above embodiment, the case where the housing 7 and the bearing sleeve 8 accommodated in the inner periphery of the housing 7 are separated has been described. However, the housing 7 and the bearing sleeve 8 may be integrated. Yes (the same applies to the housings 17 and 27). In this case, the integral member of the bearing sleeve 8 and the housing 7 is formed of a resin composition having the above composition using PPS as a base resin. In addition to providing the dynamic pressure generating portion on the sleeve-housing integrated member side (fixed side), the dynamic pressure generating portion can also be provided on the shaft 2, the flange portion 2 b, or the hub portion 9 side (rotation side) facing them. .

  In order to clarify the usefulness of the present invention, the required characteristics of the housing 7 were evaluated for a plurality of resin compositions having different compositions. As the base resin, one type of linear polyphenylene sulfide (PPS) was used. Moreover, the epoxy compound mix | blended with base resin used 4 thru | or 5 types of epoxy compounds from which an epoxy index differs, respectively. Moreover, one type of carbon fiber was used for the filler. Combinations and blending ratios of these base resins and epoxy compounds are as shown in FIGS.

  In this example, LC-5G manufactured by Dainippon Ink & Chemicals, Inc. was used as linear polyphenylene sulfide (PPS), and No. 1 was used as five epoxy compounds (epoxy compounds No. 1 to No. 5). Bond First (Grade; 2C, Epoxy Index; 0.42 meq / g) manufactured by Sumitomo Chemical Co., Ltd., and Reseda (Grade; GP301, Epoxy Index; 0.57 meq / g) manufactured by Toagosei Co., Ltd. ), Bond First manufactured by Sumitomo Chemical Co., Ltd. (grade; E, epoxy index; 0.84 meq / g), Bond First manufactured by Sumitomo Chemical Co., Ltd. (grade; CG5004, epoxy index; 1.34 meq / g), Epicron (grade; N-695P, epoxy index; 4.65 maq / g) manufactured by Dainippon Ink & Chemicals, Inc. was used. Further, HM35-C6S (fiber diameter: 7 μm, average fiber length: 6 mm, tensile strength: 3240 MPa) manufactured by Toho Tenax Co., Ltd. was used as the carbon fiber (PAN system). In this example, polytetrafluoroethylene (PTFE) was blended as a release agent, and specifically, KTL-620 manufactured by Kitamura Co., Ltd. was used.

  A dry blend of these raw materials based on the blending ratios shown in FIGS. 7 to 9 is supplied into a twin screw extruder with side feed (screw L / D ratio: about 30), screw rotation speed 150 rpm, temperature Melt kneading was performed at 300 to 330 ° C. After kneading, a molten strand was drawn out from a φ4 mm die hole, and after cooling, a resin composition pellet having a large grain size was produced. In addition, about the composition containing carbon fiber among the compositions shown in FIGS. 7-9, it is supplied at a predetermined | prescribed speed from the side feed part of a twin-screw extruder, and it is hard to produce the breakage of the carbon fiber during melt-kneading. I made it.

The evaluation items were (1) ion insolubility, (2) volume resistance [Ω · cm], (3) oil resistance (tensile strength reduction rate) [%], (4) There are 6 items in total: ring wear depth [μm], (5) wear depth [μm] of the sliding material, and (6) adhesive strength [N]. The evaluation method for each evaluation item (measurement method for the evaluation item value) and acceptance criteria are as follows. 10-12, the epoxy group amount [meq / 100g] in the resin composition indicates the theoretical value of the epoxy group amount contained in the specimens formed as examples and comparative examples, It is calculated based on the following calculation formula.
Amount of epoxy group in resin composition [meq / 100 g]
= Epoxy index [meq / g] of the epoxy compound blended in the resin composition
X Mixing ratio of epoxy compound [wt% (= g / 100g)]

（２）体積抵抗［Ω・ｃｍ］
ＪＩＳ ７１９４による四探針法により測定を行った。合否判定基準としては、１．０×１０⁶Ω・ｃｍ以下を合格（○）、１．０×１０⁶Ω・ｃｍを超えるものを不合格（×）とした。
（３）耐油性（引張強さ低下率）［％］
ＪＩＳ Ｋ７１１３で規定される一号ダンベルを、潤滑油中に浸漬し１２０℃の恒温槽に投入し、１０００ｈ後の引張強度を測定し、試験開始時のサンプルの引張強度からの低下率を求めた。潤滑油には、ジエステル油としてジ（２−エチルヘキシル）アゼレートを使用した。引張強度測定はＪＩＳ Ｋ７１１３に規定される方法で行い、低下率は次に示す計算式から算出した。
[（試験開始時の引張強度）−（各測定時間での引張強度）／（試験開始時の引張強度
）]×１００ [単位：％]
合否判定基準としては、浸漬開始後１０００ｈにおいて、低下率が１０％以下を合格（○）、１０％を超えるものを不合格（×）とした。
（４）リング摩耗深さ［μｍ］および
（５）摺動相手材の摩耗深さ［μｍ］
リング状の供試体を、潤滑油中でディスク状の摺動相手材に所定荷重で押し当てた状態でディスク側を回転させるリングオンディスク試験にて測定した。具体的には、φ２１ｍｍ（外径）×φ１７ｍｍ（内径）×３ｍｍ（厚み）のリング状樹脂成形体を供試体として使用した。また、表面粗さＲａ０．０４μｍ、φ３０ｍｍ（直径）×５ｍｍ（厚み）のＡ５０５６製のディスク材を摺動相手材として使用した。潤滑油には、ジエステル油としてジ（２−エチルヘキシル）アゼレートを使用した。この潤滑油の４０℃における動粘度は、１０．７ｍｍ²／ｓである。リングオンディスク試験中、供試体に対する摺動相手材の面圧は０．２５ＭＰａ、回転速度（周速）は１．４ｍ／ｍｉｎ、試験時間は１４ｈ、油温は８０℃とした。合否判定基準について、リング摩耗深さに関しては、３μｍ以下を合格（○）、３μｍを超えるものを不合格（×）とし、摺動相手材の摩耗深さに関しては、２μｍ以下を合格（○）、２μｍを超えるものを不合格（×）とした。
（６）接着力［Ｎ］
上記樹脂組成物を用い、φ１０ｍｍ×１５ｍｍの円柱状成形体<１>を射出成形にて成形する。一方、アルミニウム（Ａ５０５６相当）を用い、φ２０ｍｍ×φ１０ｍｍ×１０ｍｍのモータブラケット模擬治具<２>を製作し、この治具中央部に、前記円柱状成形体<１>との直径すき間（接着すき間）が２５μｍとなるよう内径寸法を規定した穴を加工する。円柱状成形体<１>およびモータブラケット模擬治具<２>の表面を充分に脱脂し、円柱状成形体<１>の接着面（上記成形体<１>の表面）にプライマを、モータブラケット模擬治具<２>の接着面（上記成形体<１>を上記治具<２>に挿入した際、成形体<１>と相対する治具<２>の表面）に嫌気性接着剤をそれぞれ塗布する。その後成形体<１>を治具<２>に挿入し、９０℃×１ｈで加熱硬化させる。なお、嫌気性接着剤として、スリーボンド社製「ＴＢ１３５９Ｄ」を、プライマとして、スリーボンド社製「ＴＢ１３９０Ｆ」をそれぞれ使用した。また、嫌気性接着剤の塗布量を約１０ｍｇ、プライマの塗布量を約１ｍｇ（溶剤分揮発後の成形体の重量増加分として測定）とした。
その後、治具<２>から成形体<１>を引抜き、抜去時における最大荷重を接着力とした。合格判定基準としては、接着力が１０００Ｎ以上のものを合格（○）、１０００Ｎ未満のものを不合格（×）とした。 (1) Ion Insolubility The presence or absence of elution of various ions (including Na ions) from the specimen (housing) was confirmed using ion chromatography. The specific procedure is shown below.
(A) A specimen is molded by injection molding, and the surface of the specimen is thoroughly washed with ultrapure water in advance.
(B) Put ultrapure water into an empty beaker and put the above specimen into it.
(C) The beaker is set in a thermostatic bath heated to 80 ° C. for 1 h, and ions contained on the surface and inside of the specimen are eluted in ultrapure water. On the other hand, a beaker containing only pure water into which a specimen is not charged is similarly set in a thermostatic bath for 1 h, and this is used as a blank.
(D) The amount of ions contained in the ultrapure water charged with the specimen prepared above is measured by ion chromatography (measurement value A). Separately, the amount of ions contained in the blank is also measured (measurement value B).
(E) The measurement value B is subtracted from the measurement value A to confirm the presence or absence of ion elution.
In addition, as a pass / fail criterion, ions that can be analyzed in a column generally used for ion chromatography (see Table 1 below) were detected ions. If the ions listed in the table were not detected, the test was accepted (O), and if detected, the test was rejected (X).

(2) Volume resistance [Ω · cm]
Measurement was performed by a four-probe method according to JIS 7194. As pass / fail judgment criteria, 1.0 × 10 ⁶ Ω · cm or less was accepted (◯), and a value exceeding 1.0 × 10 ⁶ Ω · cm was rejected (×).
(3) Oil resistance (Tensile strength reduction rate) [%]
The No. 1 dumbbell specified in JIS K7113 was immersed in lubricating oil and placed in a thermostatic bath at 120 ° C., the tensile strength after 1000 hours was measured, and the rate of decrease from the tensile strength of the sample at the start of the test was determined. . As the lubricating oil, di (2-ethylhexyl) azelate was used as a diester oil. The tensile strength was measured by the method specified in JIS K7113, and the decrease rate was calculated from the following formula.
[(Tensile strength at the start of the test) − (Tensile strength at each measurement time) / (Tensile strength at the start of the test)] × 100 [Unit:%]
As a pass / fail criterion, at 1000 h after the start of dipping, a decrease rate of 10% or less was accepted (◯), and a value exceeding 10% was rejected (x).
(4) Ring wear depth [μm] and (5) Wear depth of sliding counterpart [μm]
The ring-shaped specimen was measured by a ring-on-disk test in which the disk side was rotated in a state where it was pressed against a disk-shaped sliding counterpart in a lubricating oil with a predetermined load. Specifically, a ring-shaped resin molded body of φ21 mm (outer diameter) × φ17 mm (inner diameter) × 3 mm (thickness) was used as a specimen. Further, a disk material made of A5056 having a surface roughness Ra of 0.04 μm and φ30 mm (diameter) × 5 mm (thickness) was used as a sliding partner material. As the lubricating oil, di (2-ethylhexyl) azelate was used as a diester oil. The kinematic viscosity of this lubricating oil at 40 ° C. is 10.7 mm ² / s. During the ring-on-disk test, the surface pressure of the sliding counterpart against the specimen was 0.25 MPa, the rotational speed (peripheral speed) was 1.4 m / min, the test time was 14 h, and the oil temperature was 80 ° C. Regarding the pass / fail judgment criteria, regarding ring wear depth, 3 μm or less is acceptable (◯), and those exceeding 3 μm are unacceptable (×), and the wear depth of the sliding partner material is 2 μm or less (○). Those exceeding 2 μm were regarded as rejected (x).
(6) Adhesive strength [N]
Using the resin composition, a cylindrical molded body <1> of φ10 mm × 15 mm is molded by injection molding. On the other hand, φ20mm × φ10mm × 10mm motor bracket simulation jig <2> is manufactured using aluminum (equivalent to A5056). ) Is processed with a hole whose inner diameter dimension is specified so that it becomes 25 μm. Thoroughly degrease the surface of the cylindrical molded body <1> and the motor bracket simulation jig <2>, and attach the primer to the bonding surface of the cylindrical molded body <1> (the surface of the molded body <1>). Anaerobic adhesive is applied to the bonding surface of the simulated jig <2> (the surface of the jig <2> that faces the molded body <1> when the molded body <1> is inserted into the jig <2>). Apply each. Thereafter, the molded body <1> is inserted into the jig <2> and cured by heating at 90 ° C. for 1 hour. In addition, “TB1359D” manufactured by ThreeBond Co., Ltd. was used as an anaerobic adhesive, and “TB1390F” manufactured by ThreeBond Co., Ltd. was used as a primer. Moreover, the application amount of the anaerobic adhesive was about 10 mg, and the application amount of the primer was about 1 mg (measured as an increase in the weight of the molded product after volatilization of the solvent).
Thereafter, the molded body <1> was pulled out from the jig <2>, and the maximum load at the time of removal was defined as the adhesive force. As acceptance criteria, those having an adhesive strength of 1000 N or more were deemed acceptable (◯), and those having an adhesive strength of less than 1000 N were deemed unacceptable (x).

  The evaluation result regarding the evaluation items (1) to (6) of each specimen is shown in FIGS. If the epoxy index of the epoxy compound used is small as in Comparative Examples 1-11, 14, 15 or if the amount of epoxy groups in the resin composition used is too small or too large, sufficient adhesive strength (<1000 N) Can't get. When the compounding ratio of the epoxy compound with respect to the base resin (PPS) becomes excessive as in Comparative Examples 11 to 15, the physical properties that the base resin (PPS) should originally have, here, wear resistance is reduced, and sliding friction occurs. It is not possible to obtain sufficient durability against. On the other hand, in Examples 1 to 6 according to the present invention, adhesive strength, wear resistance (abrasion depth of the ring and the counterpart material), oil resistance (tensile strength reduction rate), cleanliness (ion In all aspects such as insolubility) and electrostatic removability (volume resistance), results superior to the comparative example were obtained.

It is sectional drawing of the spindle motor incorporating the hydrodynamic bearing apparatus which concerns on 1st Embodiment of this invention. It is sectional drawing of the hydrodynamic bearing apparatus which concerns on 1st Embodiment. It is sectional drawing of a bearing sleeve. It is a top view of a housing. It is sectional drawing of the hydrodynamic bearing apparatus which concerns on 2nd Embodiment of this invention. It is sectional drawing of the hydrodynamic bearing apparatus which concerns on 3rd Embodiment of this invention. It is a figure which shows the material composition of an Example. It is a figure which shows the material composition of a comparative example. It is a figure which shows the material composition of a comparative example. It is a figure which shows the comparative test result of an Example. It is a figure which shows the comparative test result of a comparative example. It is a figure which shows the comparative test result of a comparative example.

Explanation of symbols

1, 11, 21 Hydrodynamic bearing device 2, 12, 22 Shaft 2a Outer peripheral surface 2b Flange 3 Rotating member 4 Stator coil 5 Rotor magnet 6 Motor bracket (fixing member)
7, 17, 27 Housing 7a Thrust bearing surface 7e Cylindrical outer peripheral surface 8 Bearing sleeve 9 Hub portion 10 Lid members R1, R2, R11, R12, R21, R22 Radial bearing portions T1, T2, T11, T12 Thrust bearing portions

Claims (12)

A housing for a hydrodynamic bearing device capable of fixing a bearing sleeve that forms a radial bearing gap between an inner periphery and an outer peripheral surface of a shaft , and having an adhesive fixing surface with another member on the outer periphery,
Formed of a resin composition based on polyphenylene sulfide (PPS),
The resin composition is an epoxy compound or a bisphenol A type epoxy compound in which a base resin is grafted with polyolefin as a main chain and glycidyl methacrylate (GMA) as a side chain, and has two or more epoxy groups in the molecule. And an epoxy compound having an epoxy index of 0.5 meq / g or more and 4.65 meq / g or less,
A housing for a hydrodynamic bearing device, characterized in that the amount of epoxy groups in the resin composition is 8 meq / 100 g or more and 20 meq / 100 g or less, and the proportion of the epoxy compound in the resin composition is 20 vol% or less. A housing and a bearing for a hydrodynamic bearing device, in which a housing having an adhesion fixing surface with another member on the outer periphery and a bearing sleeve which is accommodated on the inner periphery of the housing and forms a radial bearing gap between the outer periphery of the shaft are integrated An integrated member with the sleeve,
Formed of a resin composition based on polyphenylene sulfide (PPS),
The resin composition is an epoxy compound or a bisphenol A type epoxy compound in which a base resin is grafted with polyolefin as a main chain and glycidyl methacrylate (GMA) as a side chain, and has two or more epoxy groups in the molecule. And an epoxy compound having an epoxy index of 0.5 meq / g or more and 4.65 meq / g or less,
A hydrodynamic bearing device housing and a bearing sleeve, characterized in that the amount of epoxy groups in the resin composition is 8 meq / 100 g or more and 20 meq / 100 g or less, and the compounding ratio of the epoxy compound in the resin composition is 20 vol% or less. Integrated member.   The housing for a hydrodynamic bearing device according to claim 1, which is a resin composition having an Na content of 2000 ppm or less.   2. The housing for a hydrodynamic bearing device according to claim 1, wherein the polyphenylene sulfide (PPS) is a linear type.   The hydrodynamic bearing device housing according to claim 1, wherein the resin composition contains carbon fiber. The housing for a hydrodynamic bearing device according to claim 5 , wherein the tensile strength of the carbon fiber is 3000 MPa or more. The housing for a hydrodynamic bearing device according to claim 5 , wherein the carbon fiber is a PAN-based fiber. 6. The housing for a hydrodynamic bearing device according to claim 5 , wherein the carbon fiber has an aspect ratio of 6.5 or more. The housing for a hydrodynamic bearing device according to claim 5 , wherein the carbon fiber is contained in the resin composition in an amount of 10 vol% or more and 35 vol% or less. A hydrodynamic bearing device comprising the housing for a hydrodynamic bearing device according to claim 1, a bearing sleeve fixed to the inner periphery of the housing, and a rotating member having a shaft. A hydrodynamic bearing device comprising: an integrated member of the housing for a hydrodynamic bearing device according to claim 2 and a bearing sleeve; and a rotating member having a shaft. Between the hydrodynamic bearing device according to claim 10 or 11 , a fixing member as another member that is bonded and fixed to an adhesive fixing surface of the housing, and fixes the hydrodynamic bearing device to the inner periphery, the stator coil, and the stator coil A motor equipped with a rotor magnet that generates an exciting force.

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