JP3852407B2 - Liquid-containing molded porous body - Google Patents

Description

TECHNICAL FIELD The present invention relates to a liquid-containing molded porous body, and more particularly to a liquid-containing molded porous body using fibers made of polytetrafluoroethylene.
BACKGROUND ART Conventional bearings include those in which grease is interposed between these members in order to reduce friction generated between the members sliding or rolling with each other. In this bearing, friction between the members is reduced by the lubricating action of the grease, but since the thickener is added to the grease, the viscosity increases at low temperatures such as in winter. For this reason, the starting resistance of the bearing is increased, and malfunction may occur. On the contrary, at a temperature exceeding the dropping point of the grease, the viscosity of the grease is lost and the grease leaks from the bearing. Moreover, the surface cleaning function for each member of grease is inferior to that of oil.
[0001]
Other bearings use oil instead of grease. In this case, the viscosity is lower than grease, so it is easy to leak from the bearing, and it is necessary to provide an oil supply mechanism for oil supply. Yes, the equipment becomes big.
[0002]
As another bearing, there is a bearing using a resin having a lower friction coefficient than that of a metal. However, although it is functionally excellent in a low load region, it generates heat and undergoes deformation deterioration when the load increases.
[0003]
As a bearing using a resin, a technique for obtaining a lubricating action by a bearing or a bearing member obtained by impregnating a porous body made of resin with oil has already been proposed.
[0004]
As this type of bearing, there is one in which a porous body is formed from a resin such as polyethylene or polypropylene, but these bearings are partially melted and deformed under a high temperature atmosphere, and cannot function as a bearing. There is a case.
[0005]
As another bearing using a resin, there is a bearing obtained by impregnating a porous body obtained by applying pressure, heating or the like to a fluororesin such as polytetrafluoroethylene (hereinafter referred to as PTFE). This bearing is excellent in heat resistance and chemical resistance, but when used as a bearing having rolling elements, such as a ball bearing and a ball screw, the load of the rolling element is locally applied to the bearing, so it can withstand the load. It may be deformed or damaged without being broken.
[0006]
As one of the reasons for such a lack of strength, the following has been clarified by the present inventors. That is, since the form of the resin used as a starting material in the production of this bearing is powder or particles, the pores formed by applying pressure, heating, etc. to the resin are uniformly dispersed in the porous body. Will be. In such a porous body, since there is no change in the density distribution, it becomes weak against the above-mentioned local load.
[0007]
And in view of such points, while processing the form of the resin as a raw material into a specific shape, and further applying means such as appropriate pressure and heating to the resin raw material, It has been found by the present inventors that a product with improved strength compared to a bearing can be obtained.
[0008]
An object of the present invention is to provide a liquid-containing molded porous body that has improved strength against external load and has the characteristics of a fluororesin.
DISCLOSURE OF THE INVENTION A liquid-containing molded porous body according to claim 1 includes a molded porous body and a liquid agent. The molded porous body is obtained by pressure-heating molding a web including a large number of fibers made of PTFE, and the fibers are heat-sealed to have a large number of pores. The liquid agent is impregnated in a large number of pores.
[0009]
In this liquid-containing molded porous body, the web is press-heated and molded, whereby the PTFE fibers are thermally fused together to crush the voids existing between the fibers to form a large number of fine pores. A large number of holes are impregnated with various liquid agents such as a lubricant and a cleaning agent. Further, since the web is fused in a state where the fiber density is high by pressure heating molding, the mechanical strength is increased. Furthermore, the PTFE fiber is stretched during the production process, and has a characteristic of excellent creep characteristics.
[0010]
When such a liquid-containing molded porous body is used as, for example, an oil-impregnated bearing or a bearing member, the strength against a load from a rolling element or a sliding body is improved, and each member is made of lubricating oil impregnated in pores. The friction generated between them can be reduced. And since the porous body containing the fiber which consists of a fluororesin is used here, it does not raise | generate a melt deformation even in the high temperature atmosphere of about 250 degreeC, and it becomes the conventional oil-containing porous body which consists of resin, such as polyethylene and a polypropylene. Compared to a wider temperature range, it can be used. Moreover, a liquid-containing molded porous body having a low friction compared to conventional resin oil-containing porous bodies can be obtained.
[0011]
Further, when this liquid-containing molded porous body is used as a retainer for holding, for example, a steel ball of a ball bearing, when the molded porous body is impregnated with a rust preventive agent, rust of each member can be prevented and the bearing A self-cleaning effect obtained by adhering the contaminants inside to the molded porous body is obtained. Therefore, here, the rust, wear powder, etc. on the bearing sliding surface are taken into the porous body, so that the malfunction of the bearing can be suppressed.
[0012]
Furthermore, when a molded porous body is impregnated with a drug and used as an application member for supplying this drug to other members, it is coated with improved mechanical strength and chemical resistance of the fluororesin. The drug can be applied while sliding against the member.
[0013]
The liquid-containing molded porous body according to claim 2 is the liquid-containing molded porous body according to claim 1, wherein the molded porous body further has a substrate made of glass fiber . The web is laminated on the surface of the base material by being entangled with the base material.
[0014]
In this liquid-containing molded porous body, the web and the base material are bonded by entanglement, but melt deformation occurs between the web and the base material due to pressurization and heating, and both are bonded more firmly. As a result, this molded porous body has different characteristics from the molded porous body made of only the web.
[0015]
Here, the liquid-containing molded porous body that has such characteristics can be used for a wider range of applications.
[0016]
The liquid-containing molded porous body according to claim 3 is the liquid-containing molded porous body according to claim 1 or 2, wherein the web further includes fibers made of a fluororesin excluding PTFE. Fibers made of PTFE and fibers made of a fluororesin excluding PTFE are mixed.
[0017]
Fluororesin has a high melting point and a low coefficient of friction, and is therefore suitable as a material for bearings or bearing parts used at high temperatures.
[0018]
Therefore, in this liquid-containing molded porous body, in particular, a liquid-containing molded porous body having excellent characteristics of a fluororesin by blending PTFE fibers and other fluororesin fibers having the same properties as this PTFE fiber. Is to be obtained.
[0019]
The liquid-containing molded porous body according to claim 4 is the liquid-containing molded porous body according to claim 1 or 2, wherein the web further includes particles of fluororesin excluding PTFE. The fibers made of PTFE and the fluororesin particles are bonded by melting.
[0020]
Here, a fluororesin having a lower specific gravity having excellent characteristics of a fluororesin is obtained by fusing PTFE fibers at a melting temperature or lower with a fluororesin having a melting temperature lower than that of PTFE. It is said.
[0021]
The liquid-containing molded porous body according to claim 5 is the liquid-containing molded porous body according to any one of claims 1 to 4, wherein the molded porous body has a non-uniform density.
[0022]
The conventional oil-containing porous body is formed by a method in which the raw resin form is heated or by simply compressing resin fibers, so that the pores are dispersed almost uniformly in the porous body. It was a thing.
[0023]
However, when such a porous body is used as a bearing or the like, if a load from a rolling element or the like is applied, a strong force acts locally on the porous body. Compared to deformation and damage.
[0024]
As a result of repeated researches in view of such points, the present inventors have obtained a porous body in which a specific portion has a density different from that of other portions by molding the porous body using a web containing PTFE fibers as a raw material. It was found that it can be obtained.
[0025]
Therefore, here, the molded porous body is molded so as to have a non-uniform density, so that it can withstand even a strong local load. In addition, with such a configuration, the liquid-containing molded porous body is provided with a desired function, for example, by molding so that the load receiving portion has a high density and the portion to which rust prevention / lubricating oil is supplied has a low density. Can be designed.
[0026]
The liquid-containing molded porous body according to claim 6 is the liquid-containing molded porous body according to any one of claims 1 to 5, wherein the liquid agent is a rust preventive / lubricant.
[0027]
When the liquid-containing molded porous body of the present invention is used for, for example, a bearing or the like, a rust preventive action and a lubricating action can be obtained when impregnated with lubricating oil. In addition, the molded porous body impregnated with rust preventive / lubricating oil can be used as a coating material and the like because the rust preventive / lubricated oil is applied to other members.
[0028]
Here, in particular, an object impregnated with rust preventive / lubricating oil is targeted, and a bearing or the like having improved strength and the characteristics of a fluororesin is obtained.
BEST MODE FOR CARRYING OUT THE INVENTION [Liquid-containing molded porous body]
FIG. 1 shows a liquid-containing molded porous body 1 in which an embodiment of the present invention is adopted.
[0029]
The liquid-containing molded porous body 1 includes a molded porous body 3 and a liquid agent.
[0030]
The molded porous body 3 has a web 5 formed by collecting a large number of fibers (staple fibers) made of PTFE. As staple fibers used for the web 5, an aqueous dispersion obtained by emulsion polymerization of tetrafluoroethylene (hereinafter referred to as TFE) is obtained through an emulsion spinning process and a firing process, and a PTFE film is fired and stretched. And those obtained through a rubbing step or the like, or those obtained by subjecting a PTFE film to a baking step, a stretching step, a splitting step, a cutting step, and the like.
[0031]
Further, since staple fibers having branches, loops, and the like are excellent in confounding property and hair removal resistance, it is preferable to obtain the staple fibers by a production method in which these occur. For this reason, what is obtained from a PTFE film through a baking process, a drawing process, rubbing with a needle blade roll rotating at a high speed, a defibrating process, and the like is preferable.
[0032]
The web 5 may further include fibers made of a fluororesin other than PTFE in addition to the staple fibers. In this case, it is preferable that the staple fiber and the fiber made of fluororesin are mixed and spun. Moreover, the web 5 may further include particles of a fluororesin other than PTFE. In this case, it is preferable that the staple fiber and the fluororesin particles adhere to each other by melting. For example, a fluorocarbon resin having a melting point different from the melting point of PTFE is partially impregnated into an aggregate of staple fibers (PTFE web) and heated under a low pressure to fuse the web and the resin. A porous body having a lower density can be obtained as compared with the case of molding from the fluororesin fiber.
[0033]
The web 5 may further include inorganic fibers in addition to the staple fibers. In this case, the staple fiber and the inorganic fiber are preferably blended. The fluororesin fibers, fluororesin particles, and inorganic fibers other than the above-mentioned PTFE may be included in the web 5 alone or in combination in the web 5.
[0034]
In the PTFE web, there are voids between the fibers when they are simply laminated, but the fibers are partially heat-melted in a state where the fiber density is increased by applying pressure and heat molding. Once applied, the voids in the web 5 are crushed to form a number of fine pores that are partially continuous. The pressure heating molding here is performed under such conditions that the fiber density is increased and sufficient strength and shape stability are obtained, and a large number of pores are not crushed.
[0035]
In the web 5 configured as described above, the short fibers constituting the web are substantially laminated on the web plane. As a result, when the web 5 is press-heated and molded, the internal short fibers move by the density change in the pressurizing direction, but have a property of being difficult to move in the direction perpendicular thereto. Therefore, when a load is applied to the web 5 from the vertical direction, for example, unlike the case where a similar force is applied to the resin powder aggregate, the vertical direction (the thickness of the web 5 depends on the magnitude of the load). The fiber density changes in the direction).
[0036]
Due to the properties of the web, the molded porous body 3 of the present invention can be molded so that the fiber density is either uniform or non-uniform during the pressure heating molding. For example, the molded porous body 3 is molded so as to be used as a member that receives a large load, such as a bearing or a bearing component, so that the portion that receives the load is molded at a high density, and the other portions are lubricated. Can be molded at a low density so as to be impregnated with a sufficient amount of lubricating oil.
[0037]
Moreover, the shaping | molding porous body 3 may further have the base material 7 which consists of fibers, such as glass fiber and a nonwoven fabric, and a metal porous body, as shown in FIG. Here, the web 5 is laminated | stacked on the surface of the base material 7 by couple | bonding with the base material 7 by the confounding. As a method of entanglement, a known method such as a water jet needle or a needle punch is used. The substrate 7 can be composed of one or more layers. When a base material consists of a several layer, the layer which contact | connects the web 5 is a layer which the web 5 can couple | bond together by entanglement, such as fibers, such as glass fiber and a nonwoven fabric, and a metal porous body. Other layers are not particularly limited. For example, the leakage of the liquid agent impregnated in the web 5 can be prevented by selecting a layer that does not allow the liquid agent to permeate as another layer. A method for bonding a plurality of layers constituting the substrate 7 is not particularly limited, and examples thereof include use of an adhesive suitable for the material.
[0038]
The liquid agent is a liquid that is impregnated into the pores of the molded porous body 3, and one having a function corresponding to the application of the liquid-containing molded porous body 1 is used as appropriate. For example, when the liquid-containing molded porous body 1 is used as a constituent member such as a bearing, a lubricating oil, a cleaning agent, an antirust oil, or the like can be used as the liquid agent. Specifically, synthetic oils and mineral oils such as silicon oil, fluorine oil, and ester oil can be used. A normal extreme pressure additive may be added to these lubricating oils to prevent seizure.
[0039]
Further, when the liquid-containing molded porous body 1 is used as, for example, an application member for applying various liquid chemicals to a predetermined object, a lubricant, paint, solvent, adhesive, surface treatment agent is used as the liquid agent. Etc. can be used.
[0040]
These liquid agents may be used alone or in combination so long as they do not adversely affect each other.
[0041]
[Oil-impregnated spacers for linear motion bearings and ball screw bearings]
Here, the case where the above-mentioned liquid-containing molded porous body 1 is used as the oil-impregnated spacer 21 of the linear motion bearing or the bearing portion of the ball screw will be described.
[0042]
In FIG. 3, the manufacturing process of the oil-impregnated spacer 21 is simply shown.
[0043]
When manufacturing this oil-containing spacer 21, first, a web obtained by defibration from a fluororesin film is laminated to a predetermined thickness. Next, the laminated body 29 is pressed and heated by being pressed by the two heaters 26 having the convex portions 26a so as to be sandwiched from both the upper and lower sides. The resulting molded porous body (spacer) 23 is impregnated with lubricating oil to obtain the oil-containing spacer 21.
[0044]
In the conventional technology for compressing resin powder, when molding is performed with a mold having a convex portion as described above, the resin powder is pressed into the convex portion when pressed by the mold. The inside of the mold is moved so that the molding pressures at the front end and the outer edge are equal. For this reason, it is difficult to obtain the molded porous body 23 with a density change, and there is a case where it is damaged due to shrinkage deformation at the time of melting.
[0045]
However, in the formation of the oil-impregnated spacer 21, the webs are laminated so as to face substantially the same plane direction, and therefore hardly contract in the thickness direction near the melting temperature, and mainly contract in the horizontal direction. Thereby, as for the laminated body 29, the fiber density becomes high in the part contact | abutted to the front-end | tip part of the convex-shaped part 26a of the heater 26, and fusion | melting of fibers is promoted in this high density state. As a result, the density of this part becomes larger than the density of other parts, and the mechanical strength of the spacer 23 increases.
[0046]
Thus, by using the fiber-shaped web for the production of the oil-impregnated spacer 21, for example, a portion where it is desired to suppress deformation due to a load from a steel ball of the bearing has a high density, and the outer edge portion is sufficiently lubricated. It is possible to obtain an oil-containing spacer 21 which is molded at a low density so that it can be impregnated, and has improved strength and sufficient lubrication. Moreover, the shrinkage cracking at the time of shaping | molding, etc. can be suppressed by producing the oil-containing spacer 21 using a web.
[0047]
Furthermore, in this oil-impregnated spacer 21, it is not necessary to add a thickener to the lubricating oil, so that the rotational resistance of the bearing is reduced, and particularly the starting resistance at a low temperature can be reduced. Moreover, since this containing spacer 21 contains the PTFE web excellent in heat resistance, it can be used in a high temperature atmosphere of about 250 ° C.
[0048]
[Oil-impregnated retainer for ball bearings]
Here, the case where the liquid-containing molded porous body 1 is used as the oil-containing retainer 31 of the ball bearing will be described.
[0049]
4 and 5 are sectional views of the ball bearing 30 provided with the oil retaining retainer 31. FIG.
[0050]
When manufacturing this oil-containing retainer 31, first, a web made of fibers obtained by defibration from a fluororesin film is formed into a cylindrical shape to obtain a felt-like cylindrical laminate. Next, this cylindrical laminated body is heated to a temperature around the melting point under pressure to shrink the web to obtain a cylindrical porous body having a predetermined strength. This cylindrical porous body is cut out at predetermined intervals in the axial direction to obtain an annular porous body. And the retainer 3 which forms the holding hole 34 of the steel ball 32 extended radially to this annular porous body at the equal intervals position of the circumferential direction is obtained. Finally, this retainer 33 is impregnated with lubricating oil to obtain an oil-containing retainer 31. Here, in order to increase the strength of the retainer 33, a web formed by blending inorganic fibers in a fluororesin may be used.
[0051]
In this oil-containing retainer 31, the same effect as the oil-containing spacer 21 described above can be obtained. In particular, the operation noise generated by the operation of the bearing 30 can be reduced by being disposed between the adjacent steel balls 32. In addition, since the steel balls 32 do not come into contact with each other, the sliding resistance can be reduced.
[0052]
Further, here, when dust material is generated in the bearing 30, the dust material is collected by the retainer 31 by the operation of the bearing 30, so that the self-cleaning effect of the bearing 30 is obtained.
[0053]
[Flat cage oil retaining needle roller holding member]
Here, a case where the liquid-containing molded porous body 1 is used as an oil-containing holding member 41 for holding a rolling element such as a needle roller in a flat cage will be described.
[0054]
6 and 7 show a flat cage 40 provided with an oil retaining member 41.
[0055]
The oil retaining member 41 can be obtained by pressurizing and heating the fluororesin web in the same manner as the oil retaining spacer 21 and the oil retaining retainer 31 described above. A holding hole 44 for holding is provided to obtain the flat cage holding member 43. Then, the oil retaining member 41 is obtained by impregnating the flat cage retaining member 43 with the lubricating oil. In addition, in this oil impregnation holding member 41, in order to give intensity | strength, you may shape | mold what used the metal porous plate as the base material 7, and entangled the web with this.
[0056]
This oil impregnation holding member 41 can obtain the same effects as those of the oil impregnation spacer 21 and the oil impregnation retainer 31 described above. In particular, when the needle roller 42 is slid with respect to a sliding member (not shown). , Lubrication and cleaning action can be obtained.
[0057]
[Oil-impregnated sliding member]
Here, the case where the liquid-containing molded porous body 1 is used as an oil-containing sliding member disposed between adjacent metal members such as bearings will be described.
[0058]
This oil-impregnated sliding member can also be obtained by subjecting a fluororesin web to pressure heating molding, similar to the above-described oil-impregnated spacer 21 and the like. Here, rust preventive oil is applied to the molded porous body obtained by molding. It is impregnated, thereby preventing rust on the sliding surface and maintaining sliding performance for a long time. Examples of the rust preventive oil used here include fluorine oil, silicon oil, ester oil, glycol oil, and olefin oil.
[0059]
In addition, the molded porous body obtained by molding the web 5 may be a laminate of a plurality of webs 5 in order to increase the strength. Moreover, the part used as a sliding surface should just be a fluororesin, and when it is thick, it may consist of another material other than the part of a sliding surface. Furthermore, the molded porous body may be formed by molding a multilayer body of a PTFE web and other fibers such as glass fibers.
[0060]
Also here, the same effects as the oil-impregnated spacer 21 and the like described above can be obtained, and in particular, a sliding member having a low elastic modulus and a large number of holes in the pressing direction can be obtained. Applicable. For example, the surface of the web can be obtained by immersing the PTFE web in a molten resin concentrate such as tetrafluoroethylene-hexafluoropropylene copolymer (FEP) or tetrafluoroethylene perfluoroalkyl vinyl ether copolymer (PFA) and drying it. A low-density porous body can be obtained by adhering a molten resin to the substrate and press-molding it at a temperature not lower than the melting point of PTFE (280 to 320 ° C.).
[0061]
[Liquid coating material]
The liquid-containing molded porous body can be used as a liquid-containing coating member for supplying a liquid agent according to various uses other than the above-described uses, and examples thereof will be described below.
[0062]
This liquid-containing coating member can also be obtained by pressure-heating molding a fluororesin web in the same manner as the oil-containing spacer 21 and the like. The density of the molded porous body is determined by the molding temperature, the molding pressure, and the molded porous body. It sets by combining suitably the material and laminated | stacked form (single or multiple layers) of the web to comprise. Examples of the liquid to be impregnated into the molded porous body include lubricating oil, dye-based paint, hydrocarbon-based, chlorine-based and aromatic-based solvents, etching corrosion liquid, alkaline cleaning liquid, and acid cleaning liquid.
[0063]
When various liquid agents are applied using such a liquid-containing application member, the molded porous body impregnated with the liquid to be applied is brought into contact with the application surface of the member to be applied, or the liquid agent is applied inside the molded porous body. This is done by supplying under pressure.
[0064]
This liquid-containing application member is a member suitable for application of various liquid agents by utilizing the porosity of the molded porous body and the non-adhesiveness and low friction of the fluororesin.
INDUSTRIAL APPLICABILITY According to the present invention, a molded porous body in which a number of fine pores are formed and the mechanical strength is increased is obtained by press-molding a web containing PTFE fibers. And, by impregnating this molded porous body with various liquids such as lubricating oil, it has excellent properties such as low friction, heat resistance, chemical resistance, etc. of fluororesin, and rust prevention and lubricating action by lubricating oil. A liquid-containing molded porous body is obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a liquid-containing molded porous body in which an embodiment of the present invention is adopted.
FIG. 2 is a cross-sectional view showing a liquid-containing molded porous body in which another embodiment of the present invention is adopted.
FIG. 3 is an explanatory diagram of a manufacturing process of an oil-containing spacer in which an embodiment of the present invention is adopted.
FIG. 4 is a partial cross-sectional view showing a ball bearing provided with an oil retaining retainer in which an embodiment of the present invention is adopted.
FIG. 5 is an axial sectional view showing the ball bearing.
FIG. 6 is a front view showing an oil retaining member in which an embodiment of the present invention is adopted.
FIG. 7 is a cross-sectional view of the oil retaining member.

Claims (6)

A molded porous body obtained by pressure-heating molding a web containing a large number of fibers made of polytetrafluoroethylene, wherein the fibers are heat-sealed with each other, and a large number of pores;
A liquid agent impregnated in the plurality of pores;
A liquid-containing molded porous body comprising: 2. The liquid-containing molding according to claim 1, wherein the molded porous body further includes a base material made of glass fiber , and the web is laminated on the surface of the base material by being entangled with the base material. Porous body.   The web further includes fibers made of a fluororesin excluding polytetrafluoroethylene, and the fibers made of the polytetrafluoroethylene and the fibers made of a fluororesin excluding the polytetrafluoroethylene are mixed. Item 3. The liquid-containing molded porous material according to Item 1 or 2.   The said web further contains the particle | grains of the fluororesin except polytetrafluoroethylene, The fiber consisting of the said polytetrafluoroethylene and the particle | grains of the said fluororesin are adhering by fusion | melting. Liquid-containing molded porous body.   The liquid-containing molded porous body according to any one of claims 1 to 4, wherein the molded porous body has a non-uniform density.   The liquid-containing molded porous body according to any one of claims 1 to 5, wherein the liquid agent is a rust preventive / lubricant.

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