JP2007262148A - Resin molded product and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin molded product increased in the adhesivity to another member. <P>SOLUTION: The resin molded product is such that a housing part 7 as the resin molded product is formed by injection molding of a resin composition with a liquid crystalline polymer as the base resin, and the adhesion fixing surface 7e to a bracket 6 as another member is subjected to ultrasonic vibration with water as a medium to fibrillate the adhesion fixing surface 7e. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a resin molded product and a method for producing the same.

  With the development of highly functional resin materials in recent years, such resin materials and resin molded products are expanding their uses as industrial materials. For example, resin molded products are used as component parts in bearing devices for motor spindles mounted on various electric devices such as information devices.

  For example, some bearing devices incorporated in a spindle motor of a disk drive device such as an HDD include a radial bearing portion that supports a shaft member in a radial direction through a fluid lubricating film formed in a radial bearing gap. . As a radial bearing portion in this type of bearing device (fluid bearing device), for example, either the inner peripheral surface of the bearing sleeve or the outer peripheral surface of the shaft member opposed to the bearing sleeve may have a fluid dynamic pressure in the bearing gap. It is known to form a dynamic pressure groove as a dynamic pressure generating portion that generates an action and to form a radial bearing gap between both surfaces (see, for example, Patent Document 1).

This type of hydrodynamic bearing device is composed of, for example, a plurality of components such as a shaft member, a bearing sleeve, a housing, or a seal member. Of these, components such as a housing and a seal member are used from the viewpoint of formability and low cost. Molding with a resin material has been studied (see, for example, Patent Documents 2 and 3).
JP 2003-239951 A JP 2003-314534 A JP 2005-265119 A

  By the way, when this type of hydrodynamic bearing device is assembled to a shaft support motor, the assembly is usually performed by bonding and fixing the outer peripheral surface of the housing to the inner peripheral surface of a metal motor bracket with an adhesive. On the other hand, since this type of component is required to have high durability (strength) against an external load, high adhesive strength is also required between the components. For example, in the above configuration example, the adhesive surface may be peeled off due to an impact caused by a drop of an information device having a built-in disk drive device such as an HDD, and the function of the bearing device and hence the magnetic disk device may be deteriorated. In particular, recently, in response to a request for an increase in disk capacity, the number of magnetic disks incorporated in the disk device has been increasing, and as a result, the impact force at the time of dropping has further increased. Is required to have higher adhesive strength. However, since a resin molded product is generally a material with poor adhesion to other members, it is difficult to obtain sufficient fixing strength.

  As a means for improving the adhesive force, for example, a method of mechanically roughening the surface of the molded product by shot blasting or the like is conceivable, but with this, a sufficient adhesive force cannot be obtained. Even when a primer containing metal ions is applied to the surface, it is difficult to obtain a sufficient adhesive force when a resin part is included on one side.

  The subject of this invention is providing the resin molded product which improved the adhesiveness with another member.

  In order to solve the above-described problems, the present invention provides a resin molded product having an adhesive fixing surface with another member, wherein the adhesive fixing surface is fibrillated.

  As described above, by fibrillating a region that becomes an adhesion fixing surface with another member, the surface area of the region is greatly increased. Therefore, the number of functional groups (the number of functional groups having affinity for the adhesive) is increased by the sum of the surface area of the generated fibrils compared to the non-fibrillated adhesive fixing surface. Can improve sex. Therefore, even if the apparent adhesion area is the same as that of the conventional one, it is possible to obtain a high adhesion force with other members due to the improvement of wettability.

  In order to solve the above-mentioned problem, the present invention provides a method for producing a resin molded product having an adhesive fixing surface with another member, and fibrillating the adhesive fixing surface by applying ultrasonic vibration to the adhesive fixing surface. A method for producing a resin molded product is provided.

  As described above, for example, ultrasonic irradiation is effective as a means for fibrillating the surface of the resin molded article. According to such means, the resin molded article can be easily obtained without using any special surface modifying means. The adhesive fixing surface can be fibrillated. Thereby, the wettability of a molding surface can be improved significantly and high adhesive fixing force can be obtained between other members.

  Examples of the resin that remarkably exhibits the fibrillation behavior of the surface include a liquid crystal polymer, and among them, an aromatic polyester is particularly preferable. With this type of resin, it is possible to easily promote fibrillation of the surface of the molded product (adhesion fixing surface) by applying ultrasonic vibration, and therefore, it is possible to further improve the adhesion fixing force.

  The fibrillation of the surface of the molded article by the ultrasonic vibration is to apply such ultrasonic vibration to the adhesive fixing surface using a liquid as a medium, preferably water having excellent cavitation force, particularly degassed water as a medium. Thus, it can be generated more effectively. In addition, the fibrillation by the application of the ultrasonic vibration can be performed together with, for example, ultrasonic cleaning of the molded product, thereby simplifying the work process.

  The resin molded product having the above configuration or the resin molded product obtained by the above method is supported by the fluid film formed in the fixed side member, the rotary side member, and the radial bearing gap so that the rotary side member can be rotated in the radial direction. A radial bearing portion is provided, and any one of the fixed side member and the rotary side member can be suitably provided as a hydrodynamic bearing device having the resin molded product.

  As described above, according to the present invention, it is possible to provide a resin molded product with improved adhesion to other members and a hydrodynamic bearing device including the resin molded product.

  Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. The “up and down” direction in the following description merely indicates the up and down direction in each drawing for the sake of convenience, and does not specify the installation direction, usage mode, or the like of the hydrodynamic bearing device. The same applies to the description from the second embodiment onwards.

  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. The spindle motor is used in a disk drive device such as an HDD, and is opposed to the hydrodynamic bearing device 1 that rotatably supports the rotating side member 3 including the shaft portion 2 through a gap in the radial direction, for example. The stator coil 4 and the rotor magnet 5 and the bracket 6 are provided. The stator coil 4 is attached to the outer diameter side of the bracket 6, and the rotor magnet 5 is attached to the outer periphery of the rotation side member 3. The housing portion 7 of the hydrodynamic bearing device 1 is fixed to the inner periphery of the bracket 6. Although not shown in the drawings, the rotation-side 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 rotation side member 3 rotates integrally with the shaft portion 2.

  FIG. 2 shows the hydrodynamic bearing device 1. The hydrodynamic bearing device 1 mainly includes a housing part 7, a sleeve part 8 fixed to the housing part 7, and a rotating side member 3 that rotates relative to the housing part 7 and the sleeve part 8. In this embodiment, the fixed-side member includes the housing portion 7 and the sleeve portion 8, and a lid member 10 that seals one end side of the housing portion 7 that opens at both ends in the axial direction.

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

  The hub portion 9 is formed of a metal material or a resin material, a disc portion 9a that covers the opening side (upper side) of the housing portion 7, a cylindrical portion 9b that extends downward in the axial direction from the outer peripheral portion of the disc portion 9a, and a cylindrical shape It comprises a disk mounting surface 9c and a flange 9d provided on the outer periphery of the portion 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.

  The shaft portion 2 is formed integrally with the hub portion 9 in this embodiment, and includes 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 portion 2 by means such as screw connection. In this embodiment, the shaft portion 2 is formed integrally with the hub portion 9. However, the shaft portion 2 is formed separately from the hub portion 9 and fixed by means such as adhesion and press-fitting. (Assembly) is also possible.

  The sleeve portion 8 is formed in a cylindrical shape with a porous body made of, for example, a metal non-porous body or sintered metal. In this embodiment, the sleeve portion 8 is formed of a sintered metal porous body mainly composed of copper and formed in a cylindrical shape, and is bonded (for example, loosely bonded) or press-fitted to the inner peripheral surface 7c of the housing portion 7. It is fixed by appropriate means such as (including press-fit adhesion) and welding (including ultrasonic welding). Of course, the sleeve portion 8 can be formed of a material other than metal, such as resin or ceramic.

  A region where a plurality of dynamic pressure grooves are arranged as a radial dynamic pressure generating portion is formed on the entire inner surface or a partial cylindrical region of the inner peripheral surface 8 a of the sleeve portion 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.

  As the thrust dynamic pressure generating portion, for example, although not shown, a region where a plurality of dynamic pressure grooves are arranged in a spiral shape is formed on the entire lower surface 8c of the sleeve portion 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. When the shaft portion 2 (rotation side member 3) rotates, the second thrust bearing portion T2 is interposed between the upper end surface 2b1. A thrust bearing gap is formed (see FIG. 2).

  The housing part 7 is a cylindrical resin molded product provided with an adhesive fixing surface 7e for adhesively fixing the bracket 6 as another member to the outer periphery. In this embodiment, the housing part 7 is formed by injection molding of a resin composition having a liquid crystal polymer as a base resin.

  Both ends in the axial direction of the housing part 7 are open, and one end side thereof is sealed with a lid member 10. A thrust bearing surface 7a is provided on the entire end surface (upper end surface) or a partial annular region on the other 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. This thrust bearing surface 7a (dynamic pressure groove 7a1 formation region) is opposed to the lower end surface 9a1 of the disk portion 9a of the hub portion 9, and a first thrust, which will be described later, between the lower end surface 9a1 when the rotating side member 3 rotates. A thrust bearing gap is formed in the bearing portion T1 (see FIG. 2).

  The opening on the other end side of the housing part 7 is sealed with a lid member 10. The lid member 10 is formed of a metal material or a resin material, and is fixed to a step portion 7 b provided on the inner peripheral side of the other end of the housing portion 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 sleeve portion 8 is fixed to the inner peripheral surface 7c of the housing portion 7 by appropriate means such as adhesion (including loose adhesion and press-fit adhesion), press-fitting, and welding.

  On the outer periphery of the housing portion 7, a tapered seal surface 7 d that gradually increases in diameter upward is formed. The tapered sealing surface 7d is an annular shape whose radial dimension is gradually reduced from the sealing side (downward) to the opening side (upward) of the housing part 7 between the inner peripheral surface 9b1 of the cylindrical part 9b. A seal 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 portion 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 part 7. In this embodiment, the adhesive fixing surface 7e has a cylindrical shape with a constant diameter, and is adhesively fixed to the inner peripheral surface 6a of the bracket 6 shown in FIG. At this time, for example, an ultraviolet curable adhesive, an anaerobic adhesive, or an epoxy adhesive is used from the viewpoint of workability, particularly curing speed and outgas characteristics.

  Here, the adhesive fixing surface 7e is fibrillated, and a plurality of fibrils (branch protrusions) are formed on the surface.

  The housing part 7 (resin molded product) having the above-described structure is obtained by, for example, injection molding a resin material (resin composition) with a mold having a mold corresponding to the housing part 7 shown in FIG. This is obtained by applying ultrasonic vibration to a region to be the adhesive fixing surface 7e and fibrillating the region. FIG. 5 shows an example. FIG. 5 (a) shows an injection molding of a resin composition in which a liquid crystal polymer, specifically, an aromatic polyester is used as a base resin and carbon fibers are blended as a filler. After that, an enlarged photograph of the vicinity of the adhesive fixing surface of the resin molded product after irradiating ultrasonic waves to the region that becomes the adhesive fixing surface with other members, FIG. 5B shows the vicinity of the adhesive fixing surface before the ultrasonic irradiation. Each shows an enlarged photo. In both figures, A shows the molding surface of the base resin (liquid crystal polymer), B shows the fibrils formed in a peeled form from the molding surface, and C shows the carbon fibers blended in the base resin.

  In this way, if the housing portion 7 (resin molded product) is formed by fibrillating the adhesive fixing surface 7e with the bracket 6, the substantial surface area of the adhesive fixing surface 7e is increased by the sum of the plurality of fibril surface areas. Can do. Therefore, the wettability with the adhesive can be greatly improved, and a high adhesive fixing force with the bracket 6 can be obtained. Further, according to such a method, even on the molding surface of the housing part 7, the wettability can be easily improved without particularly removing the skin layer.

  Further, in this embodiment, since the housing part 7 as a resin molded product is formed of a liquid crystal polymer, and in particular, a resin composition having an aromatic polyester as a base resin, the adhesion fixing surface is obtained by applying the ultrasonic vibration. A large number of fibrils (portion B in FIG. 5) can be generated in 7e, and the adhesive fixing force can be further improved.

  Further, by applying the ultrasonic vibration to the adhesive fixing surface 7e using water as a medium, the fibrillation of the adhesive fixing surface 7e accompanying the application of ultrasonic wave is promoted, and the number of fibrils B or per fibril B is increased. The surface area (length of fibrils B) can be further increased. Further, the fibrillation of the adhesive fixing surface 7 e can be performed simultaneously with the ultrasonic cleaning of the housing portion 7. Thereby, cleaning of the resin molded product (housing portion 7) and fibrillation of the adhesive fixing surface 7e can be performed in one process, and the work process can be simplified.

  In this embodiment, a liquid crystal polymer is used as the resin material forming the resin molded product (housing portion 7). Here, since the liquid crystal polymer has excellent characteristics such as a small amount of outgas generation at the time of solidification, low water absorption, high heat resistance, and the like, if the housing portion 7 is formed of the resin material, In addition, it is possible to suppress the amount of outgas generated at the time of molding the housing part 7 or after molding, and to suppress the dimensional change of the housing part 7 due to water absorption. Furthermore, the housing part 7 which can endure the temperature rise inside the bearing during the driving of the motor can be obtained. Moreover, if it is a liquid crystal polymer, since it can provide the housing part 7 with high oil resistance (low oil absorption) to the lubricating oil, it is possible to avoid problems such as stress cracks caused by the penetration of oil and for a long time. The hydrodynamic bearing device 1 that can be used and has high reliability can be provided.

  Further, by blending carbon fiber as a filler as in this embodiment, the reinforcing effect of the housing part 7 can be obtained, and the dimensional change accompanying the temperature change of the housing part 7 can be suppressed to obtain high dimensional stability. be able to. As a result, the thrust bearing gap of the first thrust bearing portion T1 during use can be controlled with high accuracy. Moreover, the high electroconductivity which carbon fiber has is expressed by mix | blending carbon fiber with base resin, and sufficient electroconductivity can be provided to the housing part 7. FIG. As a result, static electricity charged on the disk during use can be released to the grounding side member (such as the bracket 6) via the rotating side member 3 and the housing part 7 (also via the sleeve part 8).

  Thus, if the housing part 7 is formed of the above-mentioned resin molded product, high oil resistance, low outgas properties, high fluidity during molding, low water absorption, high heat resistance, and high adhesion to the bracket 6 are obtained. Thus, the durability and reliability of the hydrodynamic bearing device 1 and the disk drive device incorporating this bearing device can be improved. Furthermore, the housing part 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.

  By assembling and fixing the housing portion 7 to the bracket 6 as described above, the assembly of the hydrodynamic bearing device 1 to the motor is performed. At this time, 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 azelate (DOZ) are preferred.

  In the hydrodynamic bearing device 1 having the above configuration, when the shaft portion 2 (rotation side member 3) rotates, a region that forms a radial bearing surface of the inner peripheral surface 8a of the sleeve portion 8 (formation region of the two dynamic pressure grooves 8a1 and 8a2 at the upper and lower portions) ) Is opposed to the outer peripheral surface 2a of the shaft portion 2 via a radial bearing gap. As the shaft portion 2 rotates, the lubricating oil in the radial bearing gap is pushed into 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 the first radial bearing portion R1 and the second radial bearing portion R2 that support the shaft portion 2 in a non-contact manner in the radial direction.

  At the same time, a thrust bearing gap between the thrust bearing surface 7a (dynamic pressure groove 7a1 formation region) of the housing portion 7 and the lower end surface 9a1 of the hub portion 9 (disk portion 9a) facing the thrust bearing surface 7a, and the sleeve portion 8 An oil film of lubricating oil is formed in the thrust bearing gap between the lower end surface 8c (dynamic pressure groove forming region) and the upper end surface 2b1 of the flange portion 2b facing the lower 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 rotation-side member 3 in the thrust direction in a non-contact manner are configured 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 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 portion 7 (thrust bearing portion T1), and a plurality of dynamics are provided on the lower end surface 8c of the sleeve portion 8. Although the case where the thrust bearing surface in which the pressure 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 portion 2 has a straight shape without the flange portion 2b. Therefore, the housing part 7 can be made into the bottomed cylindrical shape integrally formed with the resin material by making the cover member 10 into the bottom part. The shaft portion 2 and the hub portion 9 can be integrally formed of metal or resin, and the shaft portion 2 can be formed separately from the hub portion 9.

  FIG. 5 shows a hydrodynamic bearing device 11 according to the second embodiment of the present invention. In this embodiment, the shaft portion (rotation side member) 12 includes a flange portion 12b provided integrally or separately at the lower end thereof. The housing portion 17 includes a cylindrical side portion 17a, and a bottom portion 17b that forms a separate structure from the side portion 17a and is positioned at the lower end portion of the side portion 17a. A seal portion 13 projecting inwardly from the upper end portion of the side portion 17 a of the housing portion 17 is formed integrally with the housing portion 17. Although not shown in the figure, the upper end surface 17b1 of the bottom portion 17b of the housing portion 17 is formed with a region in which, for example, a plurality of dynamic pressure grooves are arranged in a spiral shape, and the lower end surface 8c of the sleeve portion 8 is similar. A region in which the dynamic pressure grooves are arranged in the shape is formed. A first thrust bearing portion T11 is formed between the lower end surface 8c of the sleeve portion 8 and the upper end surface 12b1 of the flange portion 12b of the shaft portion 12, and the upper end surface 17b1 of the bottom portion 17b of the housing portion 17 and the flange portion 12b A second thrust bearing portion T12 is formed between the lower end surface 12b2. In this embodiment, the fixed side member is constituted by a housing part 17, a sleeve part 8, and a bottom part 17b, which are integrally provided with a seal part 13.

  In this embodiment, the side portion 17 a of the housing portion 17 is formed of a resin material together with the seal portion 13. Therefore, if the side portion 17a of the housing portion 17 is molded with the same resin composition as that of the first embodiment and a means for fibrillation (ultrasonic irradiation) is applied, the bracket (not shown) is used. High adhesive strength can be obtained. Moreover, the housing part 17 excellent in oil resistance, abrasion resistance, cleanliness, dimensional stability, moldability, etc. can be obtained.

  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 27a of the housing portion 27, and is fixed to the inner periphery of the upper end portion of the housing portion 27 by means such as adhesion, press fitting, or welding. Further, the bottom 27b of the housing part 27 is molded with a resin material integrally with the side part 27a of the housing part 27, and forms a bottomed cylindrical shape. Here, the fixed side member includes the housing portion 27, the sleeve portion 8, and the seal portion 23. Other configurations are the same as those in the second embodiment, and thus description thereof is omitted.

  In this embodiment, the housing part 27 is integrally formed of a resin material with the side part 27a and the bottom part 27b. Therefore, if the side part 27a of the housing part 27 is molded with the same resin composition as that of the first embodiment, and a means for fibrillation (irradiation with ultrasonic waves) is applied, a bracket (not shown) is used. The housing part 27 excellent in oil resistance, abrasion resistance, cleanliness, dimensional stability, moldability, etc. can be obtained including the adhesive strength between them.

  In addition, although the above embodiment (1st-3rd embodiment) demonstrated the case where the housing part 7 and the sleeve part 8 accommodated in the inner periphery of the housing part 7 were made into a different body, these housing parts 7 and the sleeve portion 8 can be integrated (the same applies to the housing portions 17 and 27). Further, the dynamic pressure generating portion can be provided on the side of the fixed side member such as the housing portion 7 and the sleeve portion 8, or can be provided on the side of the rotating side member 3 facing these.

  Moreover, although the above embodiment demonstrated the case where the resin molded product as the housing parts 7, 17, and 27 was formed with the resin composition which uses a liquid crystal polymer as a base resin, the surface of a molded product can be fibrillated. Other resins can be used as long as they can be fibrillated by application of ultrasonic vibration. Moreover, not only carbon fibers but also two or more kinds of various fillers can be filled in accordance with functions and characteristics required by the components such as metal fibers, glass fibers, whiskers and other inorganic materials.

  Moreover, in the above embodiment, although the housing parts 7, 17, and 27 were illustrated as a resin molded product which has an adhesive fixing surface with another member, it is not restricted to this member in particular. For example, instead of the housing parts 7, 17, 27, the sleeve part 8, the lid member 10, the bottom part 17 b, or the seal part 23 may be the resin molded product. Speaking of the components of the hydrodynamic bearing device 1, not only the fixed member but also the components constituting the rotating member 3, such as the shaft portions 2 and 12, the flange portions 2b and 12b, or the hub portion 9, are formed by the above resin molding. It can also be a product. Of course, parts other than the constituent parts of the hydrodynamic bearing device 1, such as the bracket 6, can be used as the resin molded product.

  Further, if there is a member that is adhesively fixed to the resin molded product, the surface becomes an adhesive fixing surface, and the member that is adhesively fixed corresponds to the other member. For example, in the first embodiment, when the sleeve portion 8 is bonded and fixed to the housing portion 7, the inner peripheral surface 7c of the housing portion 7 is an adhesive fixing surface, and the sleeve portion 8 is another member to which the sleeve portion 8 is bonded and fixed. Similarly, when the lid member 10 is bonded and fixed to the housing portion 7, an adhesive fixing surface is provided on the step portion 7b of the housing portion 7, and the lid member 10 bonded and fixed thereto is the other member.

  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 a wedge-shaped radial gap (bearing gap) is formed between the outer peripheral surface 2a of the opposing shaft portion 2 (or shaft portion 12).

  Alternatively, the inner peripheral surface 8a of the sleeve portion 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 a shaft portion opposed to the inner peripheral surface A so-called perfect circle bearing can be constituted by the two perfect circular outer peripheral surfaces 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 description, the lubricating oil is exemplified as the fluid that fills the inside of the hydrodynamic bearing device 1 and generates a dynamic pressure action in the radial bearing gap or the thrust bearing gap. A fluid capable of generating a pressure action, for example, a gas such as air, a fluid lubricant such as a magnetic fluid, or lubricating grease may be used.

  The hydrodynamic bearing device provided with the resin molded product according to the present invention is not limited to a disk drive device such as a HDD because of its high bearing performance and durability, and for example, a polygon scanner motor or projector of a laser beam printer (LBP). It can be suitably used as a bearing device for motors for electric devices such as information devices such as color wheel motors or fan motors.

  In order to clarify the usefulness of the present invention, the required characteristics of the housing part 7, specifically, the resin molded product having a fibrillated surface and the conventional resin molded product having no fibrillated surface, specifically, < Evaluations were made for 1> wettability and <2> adhesive strength (extraction force). In both tests <1> and <2>, Sumika Super E6406C manufactured by Sumitomo Chemical Co., Ltd. was used as the LCP as the test piece material. Moreover, ultrasonic irradiation to the test piece surface was performed for 10 minutes at 44 kHz, 180 w (irradiator: Branson 8510).

<1> Wettability evaluation test A plate material of 12.5 × 150 × 2 mm is prepared, and the wettability, specifically contact with the fibrillated surface and the non-fibrillated surface of the test piece, respectively. The corner was measured. The number of tests was n = 5. Water was used as a wettability evaluation medium.

<2> Extraction force evaluation test A cylindrical test piece of φ10 × 10 mm is prepared, and the adhesion force, specifically, the adhesion of the outer peripheral surface of the test piece to those obtained by fibrillation and those not fibrillated, respectively. The removal force against the mating material was measured. The number of tests was set to n = 5 as in the wettability evaluation test <1>. A bonding partner made of aluminum (ADC12) was used. As the adhesive, TB1355 manufactured by ThreeBond Co., Ltd. was used and applied to the inner peripheral surface of the bonding partner material. Further, 1390F manufactured by Three Bond Co., Ltd. was used as a primer, and applied to the outer periphery of the test piece. Adhesion and fixation were performed by leaving the materials in a combined state for 5 minutes or longer (room temperature) and then baking at 90 ° C. for 1 hour. The adhesion gap is 20 μm to 30 μm in diameter.

  FIG. 8 shows the test results of the wettability evaluation test <1> and the removal force evaluation test <2>. From the figure, it can be seen that wettability is improved (contact angle is decreased) by fibrillating the surface. In addition, significant improvement in removal force (adhesion strength) was observed due to fibrillation.

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. (A) is an enlarged photograph of the vicinity of the adhesive fixing surface of the resin molded product after irradiation with ultrasonic waves, and FIG. 5 (b) is an enlarged photograph of the vicinity of the adhesive fixing surface before irradiation with ultrasonic waves. 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 a test result.

Explanation of symbols

1, 11, 21 Hydrodynamic bearing device 2, 12 Shaft portion 3 Rotating side member 6 Bracket (other member)
7, 17, 27 Housing (resin molded product)
7e Adhesive fixing surface A Resin molding surface B Fibrils R1, R2 Radial bearing portions T1, T2, T11, T12 Thrust bearing portion S Seal space

Claims (6)

It is a resin molded product having an adhesive fixing surface with another member,
A resin molded product, characterized in that the adhesive fixing surface is fibrillated.   The resin molded product according to claim 1, which is molded using a liquid crystal polymer as a base resin.   The resin molded product according to claim 2, wherein the liquid crystal polymer is an aromatic polyester.   A fixed side member, a rotary side member, and a radial bearing portion that rotatably supports the rotary side member in a radial direction with a fluid film formed in a radial bearing gap. Any one of the hydrodynamic bearing apparatus which has the resin molded product in any one of Claims 1-3. A method for producing a resin molded product having an adhesive fixing surface with another member,
A method for producing a resin molded product, comprising applying ultrasonic vibration to the adhesive fixing surface to fibrillate the adhesive fixing surface.   The method for producing a resin molded product according to claim 5, wherein the ultrasonic vibration is applied to the adhesive fixing surface using water as a medium.