JP2012041433A - Polymer material molded product and mechanical component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polymer material molded product in which gases such as oxygen and steam hardly infiltrate, and size change and deterioration hardly occur; and to provide a mechanical component having high reliability and long life despite of at least part of the mechanical component being constituted of a polymer material.SOLUTION: A resin pulley 10 is composed of a roll bearing 11 and a resin portion 12. The resin portion 12 is formed by injection molding of a polymer material, and is attached integrally to the outer peripheral surface of an outer ring 2 of the roll bearing 11. On the surface of the resin portion 12 of the resin pulley 10, a clay membrane having a gas barrier property to suppress the infiltration of gases such as oxygen and steam and additionally having flexibility and heat resistance is coated.

Description

  The present invention relates to a polymer material molded article formed by molding a polymer material, and a machine part at least partially composed of the polymer material.

  The type of resin that is a material of the cage made of resin incorporated in the rolling bearing is determined depending on the operating temperature, operating environment, and the like. Conventionally used resins include polyamide 66, polyamide 46, polyphenylene sulfide, polyether ether ketone and the like reinforced with glass fiber or carbon fiber. Among these resins, polyamide 66 reinforced with glass fiber is most often used because of a balance of appropriate heat resistance, strength characteristics, and cost.

  However, even in a temperature environment where the polyamide 66 is sufficiently usable, the rolling bearing is used in an environment in which the amide bond existing in the chemical structure of the polyamide 66 is affected by an aggressive agent. In some cases, polyphenylene sulfide, polyether ether ketone, or the like, which has better chemical resistance than polyamide 66, is used as a material for the cage. However, since polyphenylene sulfide and polyetheretherketone are expensive, the use of these resins as the material for the cage has led to an increase in the cost of the entire rolling bearing.

  In general, polyamide resins such as polyamide 66 (especially glass fiber reinforced products) are subjected to a humidity conditioning treatment that intentionally contains a certain amount of water for the purpose of improving toughness and suppressing changes in water absorption dimensions. ing. However, moisture absorbed in the polyamide resin is discharged out of the cage due to centrifugal force or temperature rise due to the rotation of the rolling bearing, which may cause a dimensional change and cause some trouble. .

  From such a background, a coating having a gas barrier property is provided on the surface of the resin cage to suppress the entry of external factors such as moisture that causes dimensional changes and oxygen that causes deterioration. Reliable and long-life rolling bearings have been proposed. Examples of the film having a gas barrier property include a film made of an inorganic material such as a diamond-like carbon film and a vapor deposition film of silicon particles, and a film made of an organic material such as a film of ethylene vinyl copolymer or polyvinylidene chloride. It was.

  On the other hand, as a pulley for guiding a belt for driving automobile engine accessories, a resin pulley formed by integrally molding a resin portion on the outer periphery of a rolling bearing has been conventionally employed. This resin pulley requires molding accuracy of the outer periphery of the resin part that guides the belt, strength characteristics that can withstand the tension of the belt, heat resistance to high temperatures due to continuous load use, and calcium chloride resistance (chemical resistance). Is done.

  Therefore, in order to improve the molding accuracy, strength characteristics, heat resistance, and calcium chloride resistance as described above, a reinforced polyamide 66, a reinforced polyamide 610, and a reinforced polyamide containing about 15 to 40% by mass of glass fiber are used as resin materials. 612, or a resin pulley using a composite material of polyphenylene sulfide and mineral, or a polyamide resin such as polyamide 6, polyamide 66, polyamide 11, or polyamide 12 has been proposed (see, for example, Patent Documents 1 and 2).

Patent Document 3 proposes a resin pulley using a polyamide resin composition composed of polyamide 66, polyamide 612, and glass fiber having a good balance of heat resistance, strength characteristics, and calcium chloride resistance. It has become.
Furthermore, Patent Document 4 discloses a polyamide resin composed of polyamide 66, amorphous aromatic polyamide, low water absorption polyamide, and glass fiber, which further improves the balance of heat resistance, strength characteristics, and calcium chloride resistance. Resin pulleys using the composition have been proposed and put into practical use.

  However, since the resin pulley having both heat resistance, strength characteristics, and calcium chloride resistance as described above uses an expensive low water-absorbing polyamide in addition to the polyamide 66, the resin composition is expensive. It was. Moreover, although the calcium chloride resistance has been improved due to the use of a low water-absorbing polyamide, the heat resistance and strength characteristics were lower than those using only the polyamide 66. For this reason, there is a possibility that some trouble may occur in the resin pulley due to long-term use.

  From such a background, a coating having a gas barrier property was provided on the surface of the resin part of the resin pulley to suppress the intrusion of external factors such as moisture that causes dimensional changes and oxygen that causes deterioration, A highly reliable and long-life resin pulley has been proposed. Examples of the film having a gas barrier property include a film made of an inorganic material such as a diamond-like carbon film and a vapor deposition film of silicon particles, and a film made of an organic material such as a film of ethylene vinyl copolymer or polyvinylidene chloride. It was.

Japanese Patent No. 3506735 Japanese Patent No. 2838037 JP 2000-2317 A JP 2007-232106 A

However, the coating made of an inorganic material as described above has a very excellent gas barrier property and does not deteriorate the gas barrier property even at a high temperature. There was a risk of external factors such as oxygen and oxygen entering. In addition, the coating made of an organic material as described above has high flexibility but low heat resistance. Therefore, although it exhibits excellent gas barrier properties when used at low temperatures, the coating gradually increases at high temperatures. There was a possibility that the gas barrier property would deteriorate due to deterioration.
SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to solve the above-mentioned problems of the prior art and to provide a polymer material molded article that is difficult for gas such as oxygen and water vapor to enter and hardly undergo dimensional change and deterioration. It is another object of the present invention to provide a mechanical component with high reliability and long life despite being at least partially made of a polymer material.

In order to solve the above problems, the present invention has the following configuration. That is, the polymer material molded article according to claim 1 of the present invention is a polymer material molded article formed by molding a polymer material, wherein the surface is coated with a clay film made of clay and having gas barrier properties. And
The polymer material molded product according to claim 2 of the present invention is a polymer material molded product obtained by molding a polymer material, and a clay film composed of clay and a polymer substance and having a gas barrier property is provided on the surface. It is characterized by being coated.

  Furthermore, the polymer material molded product according to claim 3 of the present invention is the polymer material molded product according to claim 2, wherein the polymer substance is dextrin, starch, cellulosic resin, gelatin, agar, wheat flour, Gluten, alkyd resin, polyurethane resin, epoxy resin, fluororesin, acrylic resin, methacrylic resin, phenol resin, polyamide resin, polyester resin, polyimide resin, polyvinyl resin, polyethylene glycol, polyacrylamide, polyethylene oxide, protein, deoxyribonuclein It is at least one of acid, ribonucleic acid, and polyamino acid.

Furthermore, the polymer material molded article according to claim 4 of the present invention is the polymer material molded article according to claim 2 or claim 3, wherein the proportion of the clay in the clay film is 60 mass% or more and 95 mass%. It is characterized by being less than%.
Furthermore, the polymer material molded article according to claim 5 according to the present invention is the polymer material molded article according to any one of claims 1 to 4, wherein the clay is mica, vermiculite, montmorillonite, iron montmorillonite, It is characterized by being at least one of beidellite, saponite, hectorite, stevensite, and nontronite.

Furthermore, the polymer material molded product according to claim 6 of the present invention is the polymer material molded product according to any one of claims 1 to 5, wherein the clay film has a plurality of clay particles oriented. It is characterized by having a structure in which clay layers are laminated.
Furthermore, in the mechanical part of claim 7 according to the present invention, at least a part of the mechanical part made of a polymer material is the part made of the polymer material according to any one of claims 1 to 6. It is a polymer material molded article as described.
Furthermore, the mechanical component of claim 8 according to the present invention is the mechanical component of claim 7, which is a rolling bearing, a linear motion guide device, a ball screw, a pulley, or a gear for an electric power steering device. To do.

  Since the polymer material molded article of the present invention includes a clay film having gas barrier properties that suppress the invasion of gases such as oxygen and water vapor, flexibility, and heat resistance, dimensional change and deterioration are unlikely to occur. In addition, the mechanical component of the present invention has high reliability and a long life despite being at least partially made of a polymer material.

It is a front view which shows the structure of the resin pulleys which are 1st embodiment of the machine component which concerns on this invention. It is AA sectional drawing of the resin pulleys of FIG. It is a fragmentary longitudinal cross-section which shows the structure of the cylindrical roller bearing which is 2nd embodiment of the machine component which concerns on this invention. It is a perspective view of the holder | retainer integrated in the cylindrical roller bearing of FIG. It is a fragmentary longitudinal cross-section which shows the structure of the angular ball bearing which is a modification of 2nd embodiment. It is a perspective view of the holder | retainer integrated in the angular ball bearing of FIG. It is a longitudinal cross-sectional view which shows the structure of the deep groove ball bearing which is another modification of 2nd embodiment. It is a perspective view of the crown-shaped cage incorporated in the deep groove ball bearing of FIG. It is a figure which shows the structure of the electric power steering apparatus of a motor vehicle. FIG. 10 is a cross-sectional view of a housing portion of the electric power steering device of FIG. 9. It is a perspective view which shows the structure of the reduction gear for electric power steering apparatuses which is 3rd embodiment of the machine component which concerns on this invention.

Embodiments of a polymer material molded article and a machine part according to the present invention will be described in detail with reference to the drawings.
The polymer material molded article of the present embodiment is a polymer material molded article formed by molding a polymer material, and at least a part of the surface (preferably the entire surface) is covered with a clay film having gas barrier properties. It has been done. This clay film may be composed only of clay, or may be composed of clay and a polymer substance.

  Since the clay film has a gas barrier property that suppresses the invasion of gases such as oxygen and water vapor, the polymer material molded article coated with the clay film is less susceptible to deterioration due to oxygen and dimensional changes due to water absorption. In addition, since the water vapor permeability is low, the amount of water contained in the polymer material molded product is unlikely to decrease. Therefore, a dimensional change due to a change in the amount of moisture hardly occurs. Furthermore, since the clay film is excellent in resistance to various chemicals such as a snow melting agent (calcium chloride), the polymer material molded article coated with the clay film is less prone to problems caused by the chemical.

  Furthermore, since the clay film has flexibility, the clay film is hardly damaged and the gas barrier property is not easily lowered. Therefore, the polymer material molded article coated with the clay film maintains an excellent gas barrier property over a long period of time. Furthermore, since the clay film has heat resistance, the polymer material molded article coated with the clay film is not easily deteriorated even when used at a high temperature, and the gas barrier property is not easily lowered.

In addition, if the clay film is composed only of clay, a strong clay film may be difficult to form, but if a polymer substance is included in the clay film, the polymer substance serves as a binder, It becomes easy to form a strong clay film.
Here, the clay film will be described in more detail. The kind of clay is not particularly limited, and may be natural clay or synthetic clay. However, mica, vermiculite, montmorillonite, iron montmorillonite, beidellite, saponite, hectorite, stevensite, and nontronite are preferable, and natural smectite and synthetic smectite are more preferable. These clays may be used alone or in combination of two or more.

  Further, the type of the polymer substance that forms the clay film together with clay is not particularly limited, but a water-soluble polymer substance having hydrophilicity by providing a polar group in the main chain or side chain is preferable. Since the water-soluble polymer substance and clay have an affinity for each other, for example, when both are mixed in water, they are easily combined and complexed. As a result, the combined polymer substances are bonded to each other, and the effect of improving the strength of the clay film is obtained.

  Examples of polymer substances include dextrin, starch, cellulosic resin, gelatin, agar, wheat flour, gluten, alkyd resin, polyurethane resin, epoxy resin, fluorine resin, acrylic resin, methacrylic resin, phenol resin, polyamide resin, polyester resin , Polyimide resin, polyvinyl resin, polyethylene glycol, polyacrylamide, polyethylene oxide, protein, deoxyribonucleic acid, ribonucleic acid, and polyamino acid. These polymer substances may be used alone or in combination of two or more.

Examples of the cellulose resin include nitrocellulose and cellulose acetate. Examples of the polyvinyl resin include polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinyl acetate, polyvinyl alcohol, and polyacrylonitrile.
In a clay film composed of clay and a polymer material, the proportion of clay in the clay film is preferably 60% by mass or more and less than 95% by mass. When the proportion of the clay is less than 60% by mass, the proportion of the polymer material as the binder is high, so that the clay film has a property close to an organic film. For this reason, there is a risk that the gas barrier property is lowered under high temperature conditions. On the other hand, when the proportion of the clay is 95% by mass or more, the proportion of the polymer material as the binder is low, and thus the clay film has properties close to those of the inorganic film. Therefore, pinholes and cracks are likely to occur, and a strong clay film may be difficult to form.

Furthermore, the clay film preferably has the following structure. That is, the clay film preferably includes a clay layer in which a plurality of clay particles are oriented, and a plurality of the clay layers are laminated. A plurality of cations are preferably arranged between adjacent clay layers. That is, it is preferable that a cation is arranged between the clay particles constituting the clay layer and the clay particles constituting another clay layer adjacent to the clay layer. And if the ratio of the clay particle which has a cation is 60 to 95% among all the clay particles which comprise a clay film, the gas barrier property and softness | flexibility of a clay film will become more excellent.
Furthermore, the thickness of the clay film is not particularly limited, but is preferably 1 μm or more and 50 μm or less. If the thickness of the clay film is less than 1 μm, the gas barrier property may be insufficient, and if it exceeds 50 μm, the shape of the polymer material molded product may be adversely affected.

On the other hand, the type of polymer material constituting the polymer material molded product is not particularly limited, and examples thereof include polyamide resin, polyphenylene sulfide, and polyether ether ketone. However, considering the cost of the polymer material molded product, a polyamide resin is preferable. Examples of the polyamide resin include aliphatic polyamide resins such as polyamide 11, polyamide 12, polyamide 46, polyamide 6, polyamide 66, polyamide 610, and polyamide 612, and aromatic polyamide resins such as modified polyamide 6T and polyamide 9T. Among these polyamide resins, relatively inexpensive polyamide 66 and polyamide 46 are used.
Is more preferable. These polymer materials may be used alone or in combination of two or more.

  Moreover, you may use the resin composition which consists of resin and a fiber reinforcement as a polymeric material. Then, the heat resistance and strength characteristics of the polymer material are excellent. Examples of the fiber reinforcing material include glass fiber and carbon fiber. A polyamide resin reinforced with glass fiber (particularly polyamide 66) is most suitable because it has excellent heat resistance and strength properties and is inexpensive. Further, the polymer material may be blended with various additives such as a lubricant, a heat stabilizer, an antioxidant, a thermal conductivity improver, and a plasticizer.

A method for molding such a polymer material is not particularly limited, and a conventional resin molding method can be employed without any problem. Examples thereof include a melt molding method such as an injection molding method, a molding method by machining, and a sintering molding method.
A polymer material molded article coated with such a clay film is less prone to problems such as dimensional changes, oxygen and chemical degradation, and it is less likely to cause such problems over a long period of time even when used at high temperatures. It is suitable as a member constituting a machine part such as a rolling bearing. A member made of a polymer material is prone to the above-mentioned problems as compared with a metal member, and thus tends to reduce the reliability and life of machine parts. The component is reliable and has a long life despite being at least partially composed of a polymeric material.

Mechanical parts to which the polymer material molded product of the present embodiment can be applied are not particularly limited, and examples thereof include a rolling bearing, a linear motion guide device, a ball screw, a pulley, or a gear for an electric power steering device. It is done.
Here, the manufacturing method of the polymeric material molded article which coat | covered the clay film is demonstrated. The method for coating the clay film is not particularly limited, and a general method can be adopted without any problem. For example, (1) clay (or clay and a polymer substance) is uniformly dispersed in a dispersion medium. Dispersion adjustment process for preparing paste-like clay dispersion, (2) Coating process for coating clay dispersion liquid on the surface of polymer material molded product, (3) Coating the surface of polymer material molding product And a drying step of forming a clay film by removing the dispersion medium from the clay dispersion.

Next, the above three steps will be described in detail.
(1) About dispersion liquid adjustment process As a dispersion medium, the mixed solvent of water, an organic solvent, or water and an organic solvent is preferable. The clay concentration in the clay dispersion is preferably 0.5% by mass or more and 10% by mass or less. If the clay concentration is less than 0.5% by mass, drying may take a long time. If it exceeds 10% by mass, the clay particles are difficult to disperse in the dispersion medium, and the clay particles are difficult to be oriented uniformly. A clay film may not be obtained. In order to make such inconvenience less likely to occur, the clay concentration is more preferably set to 1% by mass or more and 3% by mass or less.

  In the case of using a polymer substance together with clay, the ratio of the polymer substance in the total amount of clay and polymer substance is preferably 40% by mass or less, and preferably 5% by mass or more and 20% by mass or less. More preferred. If the ratio of the polymer substance is more than 40% by mass, the polymer substance may be dispersed unevenly in the clay film. If the polymer substance is unevenly distributed in the clay film, the uniformity of the clay film is lowered, so that the effect of using the polymer substance may be lowered. However, the optimum ratio of the polymer substance is determined depending on the type of clay or dispersion medium, or the contents of the coating process or drying process.

  The type of organic solvent used as the dispersion medium is not particularly limited, but aromatic hydrocarbon solvents such as benzene and toluene, ether solvents such as tetrahydrofuran, and ketone solvents such as acetone and methyl ethyl ketone. Can be given. Further examples include amide solvents such as dimethylformamide, ester solvents such as ethyl acetate, alcohol solvents, and halogenated hydrocarbon solvents. These organic solvents may be used alone as a dispersion medium, or a mixed solvent obtained by mixing two or more kinds may be used as a dispersion medium. In addition, it is good to select the organic solvent to be used suitably according to the state of organication of clay.

  As a method for preparing a clay dispersion, clay (or clay and a polymer substance) is added to a dispersion medium, dispersed by a conventional means, and then dispersed under mild drying conditions (for example, heated to 50 ° C.). There is a method in which the medium is slowly evaporated to increase the clay concentration to a predetermined value. Alternatively, there is a method in which clay (or clay and a polymer substance) is added to a dispersion medium so that the concentration thereof becomes a predetermined value and dispersed by a conventional means.

  The means for dispersing clay (or clay and polymer material) is not particularly limited, but shaker, paint shaker, sand mill, pearl mill, ball mill, attritor, roll mill, high-speed impeller disperser, jet mill, Examples of the dispersion method include a high-speed impact mill and an ultrasonic disperser. The resulting clay dispersion may contain agglomerates and foreign matter, so it can be filtered using a filter, strainer, wire mesh, etc. before being coated on the surface of the polymer material molded article, or centrifuged. It is preferable to separate and remove by means such as a separation method and a precipitation method.

(2) Coating process The method for coating the surface of the polymer material molded article with the clay dispersion is not particularly limited as long as the clay dispersion can be coated into a thin film having a uniform thickness. However, spray coating, air doctor coating, blade coating, dip coating, electrodeposition coating and the like can be mentioned. Moreover, you may apply | coat manually using tools, such as a spatula and a brush, so that a bubble may not be included.

  At this time, it is preferable that the surface of the polymer material molded article is subjected to a treatment for improving the adhesion of the clay film before coating with the clay dispersion. This treatment includes known surface activation treatments such as corona discharge treatment, plasma activation treatment, glow discharge treatment, reverse sputtering treatment, roughening treatment, ethyleneimine, amine, epoxy, urethane, polyester. Primer treatment using a primer agent such as a system may be mentioned.

(3) Drying process The drying method is not particularly limited as long as the dispersion medium in the clay dispersion coated on the surface of the polymer material molded article can be removed. It can be dried by placing it in an environment such as an air current. For example, when drying in a forced convection oven, the temperature is preferably 30 ° C. or higher and 100 ° C. or lower, and more preferably 50 ° C. or higher and 70 ° C. or lower. If the drying temperature is low during drying by heating, the drying time may be long.If the drying temperature is high, convection of the liquid in the clay dispersion is promoted by rapid drying, and the uniformity of the clay film may be reduced. is there.

  In addition, by supplying heat from a heat source arranged around, it is possible to perform drying without problems even in an open system. Furthermore, it is also possible to dry by irradiating heat rays, such as infrared rays. The thickness of the clay film can be controlled to an arbitrary thickness depending on the concentration of solid content (clay or clay and polymer material) in the clay dispersion, conditions for depositing clay particles, and the like.

Hereinafter, an embodiment of a machine part to which the polymer material molded article of the present embodiment is applied will be described.
[First embodiment of machine parts]
FIG. 1 is a front view showing a structure of a resin pulley that is an embodiment of a mechanical component according to the present invention, and FIG. 2 is a cross-sectional view taken along line AA of the resin pulley of FIG.
The resin pulley 10 according to this embodiment includes a rolling bearing 11 and a resin portion 12. The rolling bearing 11 holds the rolling element 3 between the inner ring 1, the outer ring 2, a plurality of rolling elements 3 that are arranged to freely roll between the two wheels 1 and 2, and the two wheels 1 and 2. A cage 4 and sealing devices 5 and 5 covering the opening between the wheels 1 and 2 are provided. Note that the cage 4 and the seal device 5 may not be provided. Further, the sealing device 5 may be a contact rubber seal as shown in FIG. 2 or a non-contact seal such as a shield.

  The resin portion 12 is formed by injection molding of a polymer material and is integrally attached to the outer peripheral surface of the outer ring 2 of the rolling bearing 11 (the polymer portion 12 is a constituent material of the present invention). Equivalent to a molded product). Specifically, the resin portion 12 includes an inner diameter side cylindrical portion 12a into which the outer ring 2 of the rolling bearing 11 is fitted, an outer diameter side cylindrical portion 12b, and a disc portion 12c that connects both the cylindrical portions 12a and 12b. , And a plurality of ribs 12 d formed radially to reinforce the resin portion 12. The outer peripheral surface 12e of the outer diameter side cylindrical portion 12b forms a belt guide surface of a driving belt (not shown). A concave groove for preventing the resin part 12 from being attached and detached is formed on the outer peripheral surface of the outer ring 2.

  The type of the polymer material constituting the resin portion 12 is not particularly limited, but in the resin pulley, in order to reduce the noise by suppressing the occurrence of vibration due to the vibration of the belt during driving, The roundness (unevenness) of the outer peripheral surface 12e of the outer cylindrical portion 12b that guides the belt is required to be good, and the mechanical strength and heat resistance to withstand the belt tension are required to be good. It is done. Therefore, as the polymer material constituting the resin portion 12, fillers such as glass fibers and carbon fibers and various additives (lubricants, thermal stabilizers, antioxidants, thermal conductivity improvers, plasticizers, etc.) are used. A resin composition blended with the resin is preferred.

  Examples of preferred resins include polyamide resins, polyphenylene sulfide, and polyether ether ketone. Examples of the polyamide resin include aliphatic polyamide resins such as polyamide 11, polyamide 12, polyamide 46, polyamide 6, polyamide 66, polyamide 610, and polyamide 612, and aromatic polyamide resins such as modified polyamide 6T and polyamide 9T.

  Judging from the balance of cost, heat resistance, and strength characteristics of the resin composition, the resin composition using polyamide 66, which is excellent in heat resistance and fatigue resistance, as a base resin and glass fiber as a reinforcing material is most preferable. The blending amount of the glass fiber is preferably 25% by mass or more and 55% by mass or less of the entire resin composition. When the blending amount of the glass fiber is less than 25% by mass, the heat resistance and strength characteristics of the resin composition may be insufficient. On the other hand, if it exceeds 55% by mass, the melt viscosity of the resin composition becomes high and the moldability may be insufficient.

  The molecular weight of polyamide 66 is preferably 13,000 to 30000 in terms of number average molecular weight in view of injection moldability, and more preferably 18000 to 26000 in terms of number average molecular weight in consideration of fatigue resistance and high molding accuracy. If the number average molecular weight of the polyamide 66 is less than 13000, the molecular weight is too low, resulting in low fatigue resistance and low practicality. On the other hand, if the number average molecular weight of the polyamide 66 is more than 30000, the fatigue resistance is excellent, but the glass fiber is contained in an amount of 25% by mass or more to achieve mechanical strength such as impact strength required for the resin pulley. When the content is less than or equal to mass%, the melt viscosity of the resin composition becomes high, and it becomes difficult to manufacture the resin portion 12 with high accuracy by an injection molding method.

The surface of the resin portion 12 of the resin pulley 10 is coated with a clay film (not shown) having flexibility and heat resistance in addition to gas barrier properties that suppress intrusion of gases such as oxygen and water vapor. ing. The clay film is most preferably coated on the entire surface of the resin portion 12, but may be coated on a part of the surface of the resin portion 12.
Since the resin pulley 10 of this embodiment is provided with a clay film on the surface of the resin portion 12, it has excellent resistance to various chemicals (for example, calcium chloride). For this reason, even if a polyamide resin such as polyamide 66, which is slightly inferior in chemical resistance, is used as the base resin of the resin composition constituting the resin portion 12, the resin portion 12 is not easily affected by the chemical. Accordingly, for example, problems caused by the snow melting agent (calcium chloride) are suppressed, so the resin pulley 10 of the present embodiment has a high reliability and a long life.

In addition, a resin composition in which a polyamide resin such as polyamide 66 is reinforced with a fiber reinforcing material has excellent molding accuracy, strength characteristics, and heat resistance, and is relatively inexpensive. Therefore, the base of the resin composition constituting the resin portion 12 is used. If a polyamide resin such as polyamide 66 is used as the resin, the resin pulley 10 of the present embodiment is inexpensive, highly reliable, and has a long life.
Furthermore, since the clay film has a gas barrier property, it is possible to block a gas such as oxygen that causes deterioration of the resin. In addition, since the clay film also has a water vapor barrier property, it is difficult for water vapor to pass therethrough and can block water (water vapor). Therefore, since the occurrence of the malfunction of the resin pulley 10 due to the deterioration of the resin portion 12 and the dimensional change due to water absorption is suppressed, the resin pulley 10 of the present embodiment has a high reliability and a long life.

Such a resin pulley 10 can be suitably used as, for example, a driving belt for engine accessories mounted on an automobile, a tensioner pulley for other belts, or an idler pulley.
This first embodiment shows an example of the present invention, and the present invention is not limited to this embodiment. For example, in the present embodiment, a deep groove ball bearing has been described as an example of a rolling bearing, but the present invention can be applied to various types of rolling bearings. For example, radial rolling bearings such as angular contact ball bearings, self-aligning ball bearings, cylindrical roller bearings, tapered roller bearings, needle roller bearings, and self-aligning roller bearings, and thrust types such as thrust ball bearings and thrust roller bearings This is a rolling bearing.

  Further, the type of rubber used for the contact rubber seal of the rolling bearing 11 is not particularly limited, but nitrile rubber, hydrogenated nitrile rubber, acrylic rubber, or the like is used as a raw rubber, and various fillers are blended therein. Can be used. Further, the type of lubricant filled in the rolling bearing 11 is not particularly limited, and general lubricating oil or grease can be used. A grease containing α-olefin oil, alkyldiphenyl ether oil or the like as a base oil, diurea or the like as a thickening agent, and additives such as an antioxidant or an antiwear agent is preferable.

[Example of the first embodiment]
The surface of the resin part of a resin pulley having a configuration substantially similar to that of the resin pulley of FIG. 1 was prepared, and the calcium chloride resistance was evaluated.
The resin pulley is formed by integrally forming a resin portion on the outer periphery of the outer ring of the deep groove ball bearing by insert molding using the deep groove ball bearing of the reference number 6203DDL18 as a core. This deep groove ball bearing has a contact rubber seal and a concave groove on the outer peripheral surface of the outer ring. Moreover, the polymer material which comprises a resin part is the polyamide 66 (UBE nylon 2020GU6 by Ube Industries, Ltd.) which contains 30 mass% of glass fiber, and contains the copper iodide type | system | group heat stabilizer. The number average molecular weight of the polyamide 66 is 20000.

As the clay constituting the clay film, natural montmorillonite (Kunipia P manufactured by Kunimine Industries Co., Ltd.) was used. 1.0 g of clay and 60 cm ^{3 of} distilled water were put together with a rotor in a plastic sealed container and shaken vigorously to obtain a uniform clay dispersion. Next, this clay dispersion was heated to 50 ° C. in a forced air oven and slowly dried to make the clay dispersion into a paste.

Then, the paste-like clay dispersion was uniformly applied to the surface of the resin part of the resin pulley using a brush. This resin pulley was put in an oven and heated for 30 minutes at a temperature of 100 ° C. to remove distilled water contained in the paste-like clay dispersion. As a result, a clay film having a thickness of 40 μm was formed on the surface of the resin portion of the resin pulley.
The calcium chloride resistance was evaluated for the resin pulley of the example manufactured as described above and the resin pulley of the comparative example having the same configuration as that of the example except that the clay pulley was not provided. . The test method is as follows.

  First, the resin pulley was immersed in hot water at 80 ° C. for 2 hours to absorb water, and then immersed in an aqueous calcium chloride solution having a concentration of 50% by mass for 5 minutes. Next, in a state where a radial load of 1470 N was applied, the resin pulley was left in the thermostat and the temperature in the thermostat was changed as follows. That is, the temperature was raised from 20 ° C. to 110 ° C. over 30 minutes, held at 110 ° C. for 2 hours, further lowered to 20 ° C. over 30 minutes, and then held at 20 ° C. for 1 hour.

Then, the temperature change was repeated as one cycle, and the resin pulley was immersed in the calcium chloride aqueous solution for 5 minutes every two cycles. The test was conducted up to 10 cycles while checking the occurrence of cracks in the resin portion every 2 cycles.
As a result, the resin pulley of the example did not crack in the resin part even after 10 cycles, whereas the resin pulley of the comparative example cracked in 2 cycles. From this result, it can be seen that the formation of the clay film on the surface of the resin portion blocked the infiltration of water (calcium chloride aqueous solution) into the resin portion, thereby improving the calcium chloride resistance.

[Second Embodiment of Machine Parts]
FIG. 3 is a partial longitudinal sectional view showing a structure of a cylindrical roller bearing which is another embodiment of the mechanical component according to the present invention, and FIG. 4 is a perspective view of a cage incorporated in the cylindrical roller bearing of FIG. is there.
The cylindrical roller bearing 20 of the second embodiment includes an inner ring 21 having a raceway surface, an outer ring 22 having a raceway surface facing the raceway surface of the inner ring 21, and a plurality of rolls disposed between the raceway surfaces. A rolling element (cylindrical roller) 23 and a resin cage 24 that holds the rolling element 23 between the inner ring 21 and the outer ring 22 are provided. The cage 24 is an outer ring guide type cage that is guided by an inner diameter surface 22 a (cage guide surface) of the outer ring 22. Although not shown, a sealing device such as a rubber seal or a shield may be provided. Further, a lubricant such as lubricating oil or grease may be disposed in the bearing inner space formed between the inner ring 21 and the outer ring 22.

  The cage 24 is formed by injection molding of a polymer material (the cage 24 corresponds to a polymer material molded product that is a constituent of the present invention). The type of the polymer material constituting the cage 24 is not particularly limited, but the cage is required to have good dimensional accuracy and have good mechanical strength and heat resistance. Desired. Therefore, as the polymer material constituting the cage 24, fillers such as glass fibers and carbon fibers and various additives (lubricants, thermal stabilizers, antioxidants, thermal conductivity improvers, plasticizers, etc.) are used. The resin composition mix | blended with resin is preferable.

  Examples of preferred resins include polyamide resins, polyphenylene sulfide, and polyether ether ketone. Examples of the polyamide resin include aliphatic polyamide resins such as polyamide 11, polyamide 12, polyamide 46, polyamide 6, polyamide 66, polyamide 610, and polyamide 612, and aromatic polyamide resins such as modified polyamide 6T and polyamide 9T.

The surface of the cage 24 is covered with a clay film (not shown) having flexibility and heat resistance in addition to gas barrier properties that suppress intrusion of gases such as oxygen and water vapor. The clay film is most preferably coated on the entire surface of the cage 24, but may be coated on a part of the surface of the cage 24.
Since the cylindrical roller bearing 20 of this embodiment is provided with a clay film on the surface of the cage 24, the cylindrical roller bearing 20 has excellent resistance to various chemicals (for example, calcium chloride). For this reason, even when a polyamide resin such as polyamide 66, which is slightly inferior in chemical resistance, is used as the base resin of the resin composition constituting the cage 24, the cage 24 is hardly affected by the chemical. Therefore, for example, since problems caused by the snow melting agent (calcium chloride) are suppressed, the cylindrical roller bearing 20 of the present embodiment has a high reliability and a long life.

In addition, since a resin composition obtained by reinforcing a polyamide resin such as polyamide 66 with a fiber reinforcing material has excellent molding accuracy, strength characteristics, and heat resistance and is relatively inexpensive, the base of the resin composition constituting the cage 24. If a polyamide resin such as polyamide 66 is used as the resin, the cylindrical roller bearing 20 of this embodiment is inexpensive, highly reliable, and has a long life.
Furthermore, since the clay film has a gas barrier property, it is possible to block a gas such as oxygen that causes deterioration of the resin. In addition, since the clay film also has a water vapor barrier property, it is difficult for water vapor to pass therethrough and can block water (water vapor). Therefore, since the occurrence of defects in the cylindrical roller bearing 20 due to the deterioration of the cage 24 and the dimensional change due to water absorption is suppressed, the cylindrical roller bearing 20 of the present embodiment has a high reliability and a long life.

  The second embodiment shows an example of the present invention, and the present invention is not limited to the present embodiment. For example, in this embodiment, a cylindrical roller bearing has been described as an example of a rolling bearing, but the present invention can be applied to various types of rolling bearings. For example, radial rolling bearings such as deep groove ball bearings, angular contact ball bearings, self-aligning ball bearings, tapered roller bearings, needle roller bearings, and self-aligning roller bearings, and thrust types such as thrust ball bearings and thrust roller bearings This is a rolling bearing.

  FIG. 5 is a partial longitudinal sectional view showing the structure of an angular ball bearing which is a modification of the second embodiment, and FIG. 6 is a perspective view of a cage incorporated in the angular ball bearing of FIG. 7 is a longitudinal sectional view showing the structure of a deep groove ball bearing which is another modified example of the second embodiment, and FIG. 8 is a perspective view of a crown-shaped cage incorporated in the deep groove ball bearing of FIG. It is. Since the structure of these angular ball bearings and deep groove ball bearings is substantially the same as the cylindrical roller bearing 20 of the second embodiment, description thereof is omitted. 5 to 8, the same or corresponding parts as those in FIGS. 3 and 4 are denoted by the same reference numerals as those in FIGS.

[Example of the second embodiment]
What formed the clay film | membrane on the surface of the resin-made crown-shaped cage | basket of the structure substantially the same as the cage | basket of FIG. 8 was prepared, and the water vapor | steam barrier property was evaluated.
The crown-shaped cage used for the evaluation is a cage incorporated in a deep groove ball bearing having a nominal number 6203, which is formed by injection molding of a polymer material. The polymer material constituting the crown cage is polyamide 66 containing 25% by mass of glass fiber (Ultramid A3HG5 manufactured by BASF) or polyamide 46 containing 30% by mass of glass fiber (DSM Japan Engineering Plastics). Stanyl TW241F6) manufactured by Susu Co., Ltd. The former polymer material contains an amine-based antioxidant and the latter polymer material contains a copper-based heat stabilizer.

Synthetic smectite was used as the clay constituting the clay film. 10.0 g of clay and 90.0 g of distilled water were put together with a rotor in a plastic sealed container and shaken vigorously to obtain a uniform clay dispersion. Next, this clay dispersion was heated to 50 ° C. in a forced air oven and slowly dried to make the clay dispersion into a paste.
Then, the paste-like clay dispersion was uniformly applied to the surface of the crown-shaped cage using a brush. This crown-shaped cage was placed in an oven and heated for 30 minutes at a temperature of 100 ° C. to remove distilled water contained in the paste-like clay dispersion. As a result, a clay film having a thickness of 30 μm was formed on the surface of the crown-shaped cage.

Evaluation of the water vapor barrier properties of the crown-shaped cage of the example manufactured as described above and the comparative example of the crown-shaped cage having the same configuration as the example except that the clay film is not provided. did. The test method is as follows.
First, the crown-shaped cage was held in a vacuum thermostat at 80 ° C. for 1 week to make it completely dry. Then, the mass of the completely dry crown-shaped cage was measured. Next, this absolutely dry crown-shaped cage was held in a high-temperature and high-humidity tank having a temperature of 120 ° C. and a relative humidity of 80% for one week to absorb moisture. And the mass of the crown-shaped cage which absorbed moisture was measured, and the moisture absorption rate was computed by the following formula. The unit of mass in the following formula is g.
Moisture absorption rate (%) = (mass after moisture absorption−absolute dry mass) / absolute dry mass × 100

  The results are shown in Table 1. In any case of the polymer material, the moisture absorption rate of the example was lower than that of the comparative example, and the moisture absorption rate was about 15% of the comparative example. From these results, it can be seen that the formation of a clay film on the surface of the crown-shaped cage has excellent barrier properties against external and internal water vapor. That is, the clay film suppressed the absorption of water vapor outside and suppressed the discharge of moisture absorbed inside to the outside.

[Third embodiment of machine parts]
FIG. 9 is a diagram showing a configuration of an electric power steering apparatus for an automobile, and FIG. 10 is a cross-sectional view of a housing portion of the electric power steering apparatus of FIG. FIG. 11 is a perspective view showing the structure of a reduction gear (worm wheel and worm) for an electric power steering apparatus which is an embodiment of the mechanical component according to the present invention.
The electric power steering device 70 for an automobile incorporates a reduction gear (worm wheel 81 and worm 82) for an electric power steering device as shown in FIG. 11 in order to transmit the output of the electric motor for generating the steering assist output to the steering shaft. ing. The worm wheel 81 and the worm 82 provided in the housing 71 of the electric power steering device 70 have a function of transmitting the rotational driving force of the electric motor 73 generated along with the rotation of the input shaft 72 to the output shaft 74. ing.

  The worm wheel 81 and the worm 82 are made of polyamide 66 (UBE Nylon 1015GU6 manufactured by Ube Industries, Ltd.) reinforced with a polymer material, for example, glass fiber (content is 30% by mass) (worm wheel 81 and The worm 82 corresponds to a polymer material molded product which is a constituent element of the present invention). The surfaces of the worm wheel 81 and the worm 82 are covered with a clay film (not shown) having flexibility and heat resistance in addition to gas barrier properties that suppress intrusion of gases such as oxygen and water vapor. The clay film is most preferably coated on the entire surface of the worm wheel 81 and the worm 82, but may be coated on a part of the surface of the worm wheel 81 and the worm 82.

  The electric power steering device 70 of the present embodiment is excellent in resistance to various chemicals (for example, calcium chloride) since the clay film is provided on the surfaces of the worm wheel 81 and the worm 82. For this reason, even if a polyamide resin such as polyamide 66, which is slightly inferior in chemical resistance, is used as the base resin of the resin composition constituting the worm wheel 81 and the worm 82, the worm wheel 81 and the worm 82 are not easily affected by the chemical. Therefore, for example, problems caused by the snow melting agent (calcium chloride) are suppressed, so that the electric power steering device 70 of the present embodiment has a high reliability and a long life.

  In addition, a resin composition in which a polyamide resin such as polyamide 66 is reinforced with a fiber reinforcing material has excellent molding accuracy, strength characteristics, and heat resistance, and is relatively inexpensive. Therefore, the resin composition constituting the worm wheel 81 and the worm 82. If a polyamide resin such as polyamide 66 is used as the base resin of the product, the electric power steering device 70 of this embodiment is inexpensive, highly reliable, and has a long life.

  Furthermore, since the clay film has a gas barrier property, it is possible to block a gas such as oxygen that causes deterioration of the resin. In addition, since the clay film also has a water vapor barrier property, it is difficult for water vapor to pass therethrough and can block water (water vapor). Therefore, since the occurrence of problems in the electric power steering apparatus 70 due to deterioration of the worm wheel 81 and the worm 82 and dimensional changes due to water absorption is suppressed, the electric power steering apparatus 70 of the present embodiment has a high reliability and a long life. is there.

  The first to third embodiments described above show examples of the present invention, and the present invention is not limited to the above-described embodiments. In the first to third embodiments, resin pulleys, cylindrical roller bearings, and reduction gears for electric power steering devices have been described as examples of machine parts. However, the present invention is applied to other various machine parts. Can be applied. For example, a rolling device such as a ball screw or a linear motion bearing.

DESCRIPTION OF SYMBOLS 10 Resin pulley 11 Rolling bearing 12 Resin part 20 Cylindrical roller bearing 24 Cage 70 Electric power steering apparatus 81 Worm wheel 82 Worm

Claims (8)

  A polymer material molded product obtained by molding a polymer material, wherein the surface is coated with a clay film made of clay and having gas barrier properties.   A polymer material molded product obtained by molding a polymer material, wherein the surface is coated with a clay film made of clay and a polymer substance and having gas barrier properties.   The polymer substance is dextrin, starch, cellulose resin, gelatin, agar, wheat flour, gluten, alkyd resin, polyurethane resin, epoxy resin, fluororesin, acrylic resin, methacrylic resin, phenol resin, polyamide resin, polyester resin, polyimide The polymer material according to claim 2, wherein the polymer material is at least one of a resin, a polyvinyl resin, polyethylene glycol, polyacrylamide, polyethylene oxide, protein, deoxyribonucleic acid, ribonucleic acid, and polyamino acid. Molding.   The polymer material molded article according to claim 2 or 3, wherein a ratio of the clay in the clay film is 60% by mass or more and less than 95% by mass.   5. The clay according to claim 1, wherein the clay is at least one of mica, vermiculite, montmorillonite, iron montmorillonite, beidellite, saponite, hectorite, stevensite, and nontronite. The polymer material molded product described in 1.   The polymer material molded article according to any one of claims 1 to 5, wherein the clay film has a structure in which a clay layer in which a plurality of clay particles are oriented is laminated.   The mechanical part at least partly composed of a polymer material, wherein the part composed of the polymer material is the polymer material molded article according to any one of claims 1 to 6. Machine parts.   The mechanical component according to claim 7, wherein the mechanical component is a rolling bearing, a linear motion guide device, a ball screw, a pulley, or a gear for an electric power steering device.

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