JP6943352B2 - Sliding member and manufacturing method of sliding member - Google Patents

Description

The present invention relates to a sliding member and a method for manufacturing the sliding member.

Generally, fluororesin has excellent slipperiness. Therefore, the fluororesin is used, for example, in the hard coat layer of the front plate of the touch panel so as to keep the user's hand slippery (see Japanese Patent Application Laid-Open No. 2014-133393).

Japanese Unexamined Patent Publication No. 2014-133393

As mentioned above, fluororesin is excellent in slipperiness, but this slipperiness is due to (1) the fluororesin has a low surface energy, so the resin itself is slippery, and (2) the surface of the fluororesin is scraped. It is considered that the generated powder plays a role of a lubricant, and a part of this powder adheres to the sliding object to become close to the friction form between fluorine and fluorine, and the friction coefficient is lowered.

However, as described above, the fluororesin has the property of being slippery while being easily worn. Therefore, if the fluororesin is used in a place where it comes into relatively strong contact with the sliding object, the durability tends to be insufficient.

From this point of view, it is conceivable to crosslink the fluororesin in order to improve the durability of the fluororesin. However, since the slipperiness of the fluororesin depends on the scraping of the surface of the fluororesin, cross-linking the fluororesin hinders the slipperiness of the fluororesin. That is, conventionally, there is a trade-off relationship between the durability and the slipperiness of the fluororesin.

Further, depending on the application, it is conceivable to apply a lubricant such as oil or grease to the surface of the layer containing the fluororesin to improve the slipperiness. However, since fluororesin is excellent in slipperiness, it is easy to repel the lubricant, and it is difficult to keep the lubricant on the surface for a long period of time.

The present invention has been made based on such circumstances, and an object of the present invention is to provide a sliding member having excellent slidability and wear resistance, and a method for manufacturing the sliding member.

The sliding member according to one aspect of the present invention made to solve the above problems includes a sliding layer containing a fluororesin as a main component, the fluororesin is crosslinked, and the sliding layer is on the outer surface. It has a plurality of grooves, and the arithmetic mean roughness Ra of the outer surface of the sliding layer is 5 μm or more.

Further, in the method for manufacturing a sliding member according to one aspect of the present invention, which has been made to solve the above problems, a sheet body containing a fluororesin as a main component has a temperature equal to or higher than the crystal melting point of the fluororesin and a low oxygen atmosphere. An irradiation step of irradiating ionizing radiation below and a groove forming step of forming a plurality of grooves on the outer surface of the sheet body after the irradiation step are provided, and the arithmetic average of the outer surface of the sheet body obtained in the groove forming step is provided. The roughness Ra is 5 μm or more.

The sliding member of the present invention is excellent in slidability and wear resistance. Further, the method for manufacturing a sliding member of the present invention can manufacture a sliding member having excellent slidability and wear resistance.

It is a schematic cross-sectional view which shows the sliding member which concerns on one Embodiment of this invention. It is a schematic partial enlarged plan view of the sliding member of FIG. FIG. 2 is an end view of the sliding member of FIG. 2 taken along the line AA. It is a schematic partially enlarged cross-sectional view which shows the state which the lubricant is applied to the outer surface of the sliding member of FIG. It is a graph which shows the relationship between the arithmetic mean roughness of the outer surface of a sliding layer and a dynamic friction coefficient in a grease coating mode. It is a graph which shows the relationship between the arithmetic mean roughness of the outer surface of a sliding layer in a dry mode, and the coefficient of dynamic friction. It is a graph which shows the relationship between the presence or absence of electron beam irradiation and the dynamic friction coefficient in a grease coating mode. It is a graph which shows the relationship between the presence or absence of electron beam irradiation in a dry mode, and a dynamic friction coefficient. It is a graph which shows the retention of grease. It is a graph which shows the relationship between the arithmetic mean roughness of the outer surface of a sliding layer, and the retention of grease.

[Explanation of Embodiments of the Present Invention]
First, embodiments of the present invention will be listed and described.

The sliding member according to one aspect of the present invention includes a sliding layer containing a fluororesin as a main component, the fluororesin is crosslinked, the sliding layer has a plurality of grooves on the outer surface, and the sliding The arithmetic mean roughness Ra of the outer surface of the moving layer is 5 μm or more.

The sliding member includes a sliding layer containing a fluororesin as a main component, and the fluororesin is crosslinked, so that the sliding member is excellent in wear resistance. Further, in the sliding member, in addition to the sliding layer having slipperiness due to the non-adhesiveness of the fluororesin, the arithmetic average roughness Ra of the outer surface of the sliding layer is within the above range. Therefore, the contact area with the sliding target member becomes small. Therefore, the sliding member is excellent in slidability.

The arithmetic average roughness Ra is preferably 10 μm or more. The sliding member may be used in a state where a lubricant is applied to the outer surface of the sliding layer. In this case, when the arithmetic mean roughness Ra is at least the above lower limit, the retention of the lubricant on the outer surface of the sliding layer can be improved, and thereby the slidability can be further improved. ..

The arithmetic average roughness Ra is preferably 35 μm or less. Depending on the application, the sliding member is used without applying a lubricant to the outer surface of the sliding layer. In this case, when the arithmetic mean roughness Ra is equal to or less than the upper limit, the decrease in slidability due to the crushing of the convex portion on the outer surface of the sliding layer can be accurately suppressed, and the sliding is excellent. It can maintain motility.

The average width of the plurality of grooves is preferably 100 μm or more and 400 μm or less, the average depth is preferably 100 μm or more and 500 μm or less, and the average interval is preferably 300 μm or more and 5500 μm or less. As described above, when the average width, the average depth, and the average interval of the plurality of grooves are within the above ranges, it is easy to reduce the contact area of the sliding layer with the sliding target member. When the sliding member is used with a lubricant applied to the outer surface of the sliding layer, the plurality of grooves are lubricated when the average width and the average depth of the plurality of grooves are within the above ranges. It is easy to retain the agent, which makes it easier to improve the slidability.

It is preferable that at least a part of the plurality of grooves is an independent groove. As described above, since at least a part of the plurality of grooves is an independent groove, the lubricant can be easily retained in the independent groove, whereby the slidability can be easily improved. Further, according to this configuration, it is possible to suppress a decrease in the strength of the sliding layer due to the plurality of grooves.

It is preferable that the plurality of grooves are arranged in a grid pattern as a whole. As described above, since the plurality of grooves are arranged in a grid pattern as a whole, the contact area of the sliding layer with the sliding target member is increased by the plurality of grooves extending in the direction along the sliding direction. It can be easily and surely made smaller. Further, when a lubricant is applied to the outer surface of the sliding layer, the lubricant tends to stay in a plurality of grooves intersecting at a relatively large angle with respect to the sliding direction. This makes it easy to improve the slidability.

It is preferable that the outer surface of the portion of the sliding layer surrounded by the plurality of grooves is formed in a dome shape. By forming the outer surface of the portion of the sliding layer surrounded by the plurality of grooves in a dome shape in this way, the contact area of the sliding layer with the sliding target member can be further reduced. Further, according to this configuration, since it is easy to spread the lubricant on the curved surface portion of the dome-shaped portion, it is easy to enhance the effect of improving the slidability by the lubricant.

Further, in the method for manufacturing a sliding member according to another aspect of the present invention, a sheet body containing a fluororesin as a main component is irradiated with ionizing radiation at a temperature equal to or higher than the crystal melting point of the fluororesin and in a low oxygen atmosphere. An irradiation step of performing the irradiation step and a groove forming step of forming a plurality of grooves on the outer surface of the sheet body after the irradiation step are provided, and the arithmetic average roughness Ra of the outer surface of the sheet body obtained in the groove forming step is set to 5 μm or more. do.

In the method for manufacturing the sliding member, after the fluororesin is crosslinked by the irradiation step, a plurality of grooves are formed on the sheet body by the groove forming step so that the arithmetic average roughness Ra of the outer surface is within the above range. As a result, the above-mentioned sliding layer can be manufactured. Therefore, the method for manufacturing the sliding member can manufacture a sliding member having excellent slidability and wear resistance.

In the present invention, the "main component" means a component having the highest content, for example, a component contained in an amount of 50% by mass or more. “Arithmetic mean roughness Ra” means a value measured with a cutoff value (λc) of 2.5 mm and an evaluation length (l) of 8 mm according to JIS-B0601: 2001. The "mean width of the groove" means the average value of the widths of any 20 points of the opening portion of the groove, excluding 5 from the large one and 5 from the small one. The "average depth of the groove" means the average value of the values obtained by removing 5 from the large depth and 5 from the small depth among the depths at any 20 points of the groove. The "average groove spacing" means the average value of the values obtained by removing 5 from the large one and 5 from the small one among the intervals of any 20 points of the opening portion of the adjacent groove. The “outer surface is dome-shaped” means a shape in which the outer surface is curved toward the surface as a whole in a cross section in the thickness direction, and includes a shape having irregularities on a part of the outer surface.

[Details of Embodiments of the present invention]
Hereinafter, an embodiment of a sliding member and a method for manufacturing the sliding member according to the present invention will be described in detail with reference to the drawings.

[Sliding member]
The sliding member of FIG. 1 is formed in a sheet shape as a whole. The sliding member includes a sliding layer 1 containing a fluororesin as a main component and a base material layer 2 laminated on one side of the sliding layer 1. The sliding member is a two-layer body consisting of a sliding layer 1 and a base material layer 2. The fluororesin is crosslinked. The sliding layer 1 forms the outermost layer on one side of the sliding member. As shown in FIGS. 2 and 3, the sliding layer 1 has a plurality of grooves 3 on the outer surface. The sliding layer 1 has an outer surface arithmetic mean roughness Ra of 5 μm or more. Although the flat plate-shaped sliding member is shown in FIG. 1, the sliding member is not limited to the shape shown in FIG. 1, for example, a cylinder in which the sliding layer 1 is arranged on the inner surface side. It may be in the form.

The sliding member is used as a member such as a fixing roller or a bearing. Specifically, the sliding member is included in the heat-resistant film in the fixing roller having a tubular heat-resistant film that is in contact with the outer peripheral surfaces of the heating roller and the heating roller and slides in the circumferential direction of the heating roller, for example. It is used as a member that constitutes the peripheral surface and as a member for non-lubricated bearings. When the fixing roller is used for the fixing roller, for example, it is used in a state where a lubricant such as grease is applied to the outer surface of the sliding layer 1. On the other hand, when the sliding member is used as a member for the non-lubricating bearing, it is used in a state where the lubricant is not applied to the outer surface of the sliding layer 1. As described above, the sliding member may be used in a state where the outer surface of the sliding layer 1 is coated with a lubricant, or may be used in a state where the lubricant is not applied.

The sliding member includes a sliding layer 1 containing a fluororesin as a main component, and the fluororesin is crosslinked, so that the sliding member is excellent in wear resistance. Further, in the sliding member, in addition to the sliding layer 1 having slipperiness due to the non-adhesiveness of the fluororesin, the arithmetic average roughness Ra of the outer surface of the sliding layer 1 is equal to or higher than the above lower limit. Therefore, the contact area with the sliding target member becomes small. Therefore, the sliding member is excellent in slidability.

Since the sliding member has improved wear resistance due to the cross-linking of the fluororesin as described above, the generation of fluororesin powder due to sliding with the sliding target member is suppressed. .. Therefore, when the sliding member is used without applying a lubricant to the outer surface of the sliding layer 1, it is difficult to obtain the effect of improving the slidability by the fluororesin powder, so that the outer surface of the sliding layer 1 is temporarily formed. If the surface is smooth, the friction coefficient of the sliding layer 1 becomes relatively high. On the other hand, in the sliding member, the contact area with the sliding target member can be reduced by setting the arithmetic average roughness Ra of the outer surface of the sliding layer 1 to be equal to or higher than the above lower limit, so that the sliding layer can be reduced. The coefficient of friction between 1 and the member to be slid can be suppressed to a relatively low value to sufficiently improve the slidability. When the arithmetic mean roughness Ra of the outer surface of the sliding layer formed of the non-crosslinked fluororesin is set to be equal to or higher than the above lower limit, the convex portion of the outer surface of the sliding layer is likely to be crushed by contact with the sliding object. , It is difficult to maintain this arithmetic mean roughness Ra. On the other hand, when the fluororesin is crosslinked, the surface pressure of the convex portion on the outer surface of the sliding layer 1 may increase, but this causes the fluororesin to be slightly worn to generate a small amount of fluororesin powder. On the contrary, the slidability is likely to be improved.

On the other hand, when the sliding layer 1 is used with a lubricant applied to the outer surface, the sliding layer containing fluororesin as a main component generally has excellent slipperiness, so that the lubricant does not easily stay on the outer surface. On the other hand, in the sliding member, the lubricant can be retained on the outer surface of the sliding layer 1 by setting the arithmetic average roughness Ra of the outer surface of the sliding layer 1 to be equal to or higher than the above lower limit. Further, in the sliding member, radicals are generated when the fluororesin is crosslinked by irradiation with ionizing radiation described later. Therefore, the sliding member has good compatibility with the lubricant due to the radicals. Therefore, the sliding member can sufficiently suppress the friction coefficient between the sliding layer 1 and the sliding target member to be relatively low and sufficiently improve the slidability.

(Sliding layer)
The sliding layer 1 is crosslinked with a fluororesin, so that the abrasion resistance is enhanced while maintaining the non-adhesiveness of the fluororesin.

Examples of the fluororesin include polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and polyvinylidene fluoride (PVDF). ), Tetrafluoroethylene-ethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), chlorotrifluoroethylene-ethylene copolymer (ECTFE), polyvinyl fluoride (PVF), fluoroolefin-vinyl ether copolymer, Examples thereof include vinylidene fluoride-tetrafluoroethylene copolymer and vinylidene fluoride-hexafluoropropylene copolymer. Among these, as the fluororesin, PTFE, PFA and FEP are preferable, PFA and PTFE are more preferable, and PTFE is further preferable from the viewpoint of mechanical strength, chemical resistance and heat resistance. The fluororesin can be used alone or in combination of two or more. However, from the viewpoint of forming the sliding layer 1 having a high degree of wear resistance, it is preferable to use PTFE alone.

The fluororesin may contain a polymerization unit derived from another copolymerizable monomer as long as the effect of the present invention is not impaired. For example, PTFE may contain polymerization units such as perfluoro (alkyl vinyl ether), hexafluoropropylene, (perfluoroalkyl) ethylene, and chlorotrifluoroethylene. The upper limit of the content ratio of the polymerization unit derived from the other copolymerizable monomer is, for example, 3 mol% with respect to the total polymerization units constituting the fluororesin.

As the lower limit of the content ratio of the fluororesin in the sliding layer 1, 60% by mass is preferable, 85% by mass is more preferable, and 98% by mass is further preferable. Further, the content ratio is particularly preferably 100% by mass. If the content ratio does not reach the lower limit, the properties such as wear resistance and heat resistance may not be sufficiently high.

The sliding layer 1 may contain other optional components. Examples of this optional component include solid lubricants, reinforcing materials and the like. When the sliding layer 1 contains a solid lubricant, a reinforcing material, or the like, the slidability can be further improved. Examples of the solid lubricant include molybdenum disulfide and the like. Examples of the reinforcing material include glass fibers (glass fibers), glass fillers such as spherical glass, and inorganic fillers such as carbon fibers, calcium carbonate, talc, silica, alumina, and aluminum hydroxide.

The upper limit of the crystal melting point temperature of the crosslinked fluororesin in the sliding layer 1 varies depending on the type of the fluororesin. For example, in the case of PTFE, 325 ° C. is preferable, 320 ° C. is more preferable, and 310 ° C. is even more preferable. .. The crystal melting point temperature decreases with the degree of cross-linking of the cross-linked fluororesin. Therefore, if the crystal melting point temperature exceeds the upper limit, the wear resistance may be insufficient due to insufficient cross-linking degree. The lower limit of the crystal melting point temperature of the crosslinked fluororesin is, for example, 290 ° C. If the crystal melting point temperature is smaller than the above lower limit, the wear resistance may be insufficient due to a decrease in heat resistance and the like. The "crystal melting point" refers to the melting point peak temperature measured by a differential scanning calorimeter (DSC) in accordance with JIS-K7121: 2012 "Method for measuring transition temperature of plastics".

The arithmetic mean roughness Ra of the outer surface of the sliding layer 1 is 5 μm or more as described above. As described above, the sliding member is a lubricant-coated sliding member used in a state where a lubricant is applied to the outer surface of the sliding layer 1, and a lubricant is applied to the outer surface of the sliding layer 1. It may be a dry type sliding member used in a non-compacted state. When the sliding member is the lubricant-coated sliding member, the lower limit of the arithmetic mean roughness Ra is preferably 10 μm, more preferably 20 μm, and even more preferably 30 μm or more. If the arithmetic mean roughness Ra is smaller than the lower limit, the contact area with the sliding target member may not be sufficiently reduced, and it becomes difficult for the lubricant to sufficiently stay on the outer surface of the sliding layer 1. There is a risk. On the other hand, the upper limit of the arithmetic mean roughness Ra is not particularly limited, but can be set to, for example, 50 μm from the viewpoint of suppressing a decrease in the strength of the sliding layer 1.

When the sliding member is the dry type sliding member, the lower limit of the arithmetic mean roughness Ra of the outer surface of the sliding layer 1 is preferably 10 μm, more preferably 15 μm. On the other hand, the upper limit of the arithmetic mean roughness Ra is preferably 35 μm, more preferably 30 μm. If the arithmetic mean roughness Ra is smaller than the lower limit, the contact area with the sliding target member may not be sufficiently reduced. On the contrary, when the arithmetic mean roughness Ra exceeds the upper limit, the convex portion on the outer surface of the sliding layer 1 may be easily crushed.

As described above, a plurality of grooves 3 are formed on the outer surface of the sliding layer 1. The shape of each groove 3 is not particularly limited, and may be, for example, a straight line or a wavy shape. Further, the arrangement of the plurality of grooves 3 is not particularly limited, and may be arranged in a striped shape, for example. However, it is preferable that the plurality of grooves 3 are arranged in a grid pattern as a whole. Since the plurality of grooves 3 are arranged in a grid pattern as a whole, the sliding member has the plurality of grooves 3 extending in the sliding direction with the sliding target member of the sliding layer 1. The contact area can be easily and surely reduced. Further, since the plurality of grooves 3 are arranged in a grid pattern as a whole, when a lubricant is applied to the outer surface of the sliding layer 1, the lubricant is applied at a relatively large angle with respect to the sliding direction. It is easy to stay in a plurality of intersecting grooves 3. Therefore, the sliding member tends to improve the slidability. The term "lattice-like" includes a shape in which the linear portions constituting the lattice are divided at one or a plurality of places.

When the plurality of grooves 3 are arranged in a grid pattern as a whole, the overall shape of the plurality of grooves 3 is preferably a square lattice shape. Further, in this case, it is preferable that a plurality of grooves 3 extending in one direction are arranged in parallel with the sliding direction. That is, when the sliding member has a cylindrical shape, it is preferable that a plurality of grooves 3 extending in one direction are arranged in the circumferential direction. According to this configuration, the sliding member slides while the contact area of the sliding layer 1 with the sliding target member is easily and surely reduced by a plurality of grooves 3 arranged in parallel with the sliding direction. It is easy for the lubricant to stay in the plurality of grooves 3 arranged perpendicular to the moving direction.

The average width (w) of the plurality of grooves 3 is preferably 100 μm or more and 400 μm or less. When the sliding member is the lubricant-coated sliding member, the lower limit of the average width (w) of the plurality of grooves 3 is more preferably 120 μm, further preferably 150 μm. On the other hand, when the sliding member is the lubricant-coated sliding member, the upper limit of the average width (w) is more preferably 350 μm and further preferably 250 μm. If the average width (w) is smaller than the lower limit, it may be difficult for the lubricant to sufficiently stay in each groove 3. On the contrary, when the average width (w) exceeds the upper limit, the effect of improving the retention of the lubricating material is not promoted so much, but the strength of the sliding layer 1 may decrease.

When the sliding member is the dry type sliding member, the lower limit of the average width (w) of the plurality of grooves 3 is more preferably 150 μm, further preferably 200 μm. On the other hand, when the sliding member is the dry type sliding member, the upper limit of the average width (w) is more preferably 370 μm and further preferably 320 μm. If the average width (w) is smaller than the lower limit, the contact area between the sliding layer 1 and the sliding target member may not be sufficiently reduced. On the contrary, if the average width (w) exceeds the upper limit, the strength of the sliding layer 1 may be insufficient.

The lower limit of the average depth (d) of the plurality of grooves 3 is preferably 100 μm, more preferably 150 μm, and even more preferably 200 μm. On the other hand, the upper limit of the average depth (d) of the plurality of grooves 3 can be appropriately designed according to, for example, the size and shape of the mesh net described later, but 500 μm is preferable, 400 μm is more preferable, and 300 μm is further preferable. .. If the average depth (d) is smaller than the lower limit, it may be difficult for the lubricant to sufficiently stay in each groove 3 when used as a lubricant-coated sliding member, for example. On the contrary, if the average depth (d) exceeds the upper limit, the strength of the sliding layer 1 may be insufficient.

The depth of each groove 3 may be substantially uniform, but it is preferably non-uniform. For example, it is preferable that the bottom of each groove 3 gradually increases in depth from the outside to the inside in the width direction. The sliding member can maintain sufficiently high slidability even when the depth of each groove 3 is non-uniform. On the other hand, in the sliding member, since the depth of each groove 3 is non-uniform, it is possible to suppress a decrease in the strength of the sliding layer 1 due to the plurality of grooves 3.

The lower limit of the average spacing (l) of the plurality of grooves 3 is preferably 300 μm, more preferably 400 μm, and even more preferably 500 μm. On the other hand, as the upper limit of the average interval (l) of the plurality of grooves 3, 5500 μm is preferable, 2000 μm is more preferable, and 1000 μm is more preferable. If the average interval (l) is smaller than the lower limit, the width of the convex portion formed between the adjacent grooves 3 of the sliding layer 1 becomes insufficient, and the convex portion may be damaged due to sliding. be. On the contrary, if the average interval (l) exceeds the upper limit, the contact area between the sliding layer 1 and the sliding target member may not be sufficiently reduced, or lubrication may occur when the sliding layer 1 is used as a lubricant-coated sliding member. The agent may not be sufficiently retained on the outer peripheral surface of the sliding layer 1.

In particular, it is preferable that the average width (w), average depth (d), and average interval (l) of the plurality of grooves 3 are all within the above ranges. The sliding member facilitates the slidability of the sliding layer 1 when the average width (w), average depth (d), and average interval (l) of the plurality of grooves 3 are all within the above ranges. And it can be surely increased.

The lower limit of the average pitch (p) between the adjacent grooves 3 is preferably 400 μm, more preferably 500 μm, and even more preferably 600 μm. On the other hand, as the upper limit of the average pitch (p), 5900 μm is preferable, 2500 μm is more preferable, and 1500 μm is further preferable. If the average pitch (p) is smaller than the lower limit, the width of the convex portion formed between the adjacent grooves 3 of the sliding layer 1 becomes insufficient, and the convex portion may be damaged due to sliding. be. On the contrary, if the average pitch (p) exceeds the upper limit, the contact area between the sliding layer 1 and the sliding target member may not be sufficiently reduced, or lubrication may occur when the sliding layer 1 is used as a lubricant-coated sliding member. The agent may not be sufficiently retained on the outer peripheral surface of the sliding layer 1. The "average pitch" means the average distance between the central axes of adjacent grooves.

It is preferable that at least a part of the plurality of grooves 3 is an independent groove. According to this configuration, the lubricant is likely to stay in the independent groove, which makes it easy to improve the slidability. Further, according to this configuration, it is possible to suppress a decrease in the strength of the sliding layer 1 due to the plurality of grooves 3.

The lower limit of the ratio of the number of independent grooves to the total number of grooves 3 formed on the outer surface of the sliding layer 1 is preferably 50%, more preferably 70%, and even more preferably 90%. When the above ratio is at least the above lower limit, the retention effect of the lubricant can be easily and surely enhanced.

Further, when the plurality of grooves 3 are arranged in a grid pattern as a whole, it is preferable that a plurality of independent grooves are formed so that the grooves 3 extending in the intersecting direction are not connected to each other. When the grooves 3 extending in the intersecting direction are connected to each other, the lubricant is excessively retained in the connecting portion, and the lubricant tends to be unevenly distributed in the connecting portion. On the other hand, when the grooves 3 extending in the intersecting direction are not connected to each other, the lubricant can be ubiquitously distributed on the outer surface of the sliding layer 1, thereby easily improving the overall slidability. Can be done.

The outer surface of the portion of the sliding layer 1 surrounded by the plurality of grooves 3 is preferably formed in a dome shape. According to this configuration, the contact area of the sliding layer 1 with the sliding target member can be made smaller. Further, according to this configuration, as shown in FIG. 4, since the lubricant X can be easily spread over the curved surface portion of the dome-shaped portion 4, it is easy to enhance the effect of improving the slidability by the lubricant X.

The lower limit of the average thickness of the sliding layer 1 is preferably 50 μm, more preferably 100 μm. On the other hand, the upper limit of the average thickness of the sliding layer 1 is preferably 1000 μm, more preferably 800 μm. If the average thickness is smaller than the lower limit, the strength of the sliding layer 1 may be insufficient or the depths of the plurality of grooves 3 may not be sufficiently deepened. On the contrary, if the average thickness exceeds the upper limit, the sliding layer 1 may become unnecessarily thick and the flexibility may be insufficient. Further, if the average thickness exceeds the upper limit, the heat dissipation may be insufficient. The "average thickness of the sliding layer" means the average value of the thickness at any 10 points where the groove is not formed.

(Base layer)
The base material layer 2 forms the outermost layer on the side opposite to the sliding layer 1 of the sliding member. The sliding member is a two-layer structure of a sliding layer 1 and a base material layer 2. The base material layer 2 contains, for example, a metal or a super engineering plastic as a main component. Note that the "super engineering plastics", long-term heat resistance is 100 ° C. or higher, the thermal deformation temperature of 0.99 ° C. or higher, a tensile strength of 5 kgf · ^{mm -2} or more and flexural synthesis modulus of 245kgf · ^{mm -2} or more Refers to resin. However, synthetic resin containing fluororesin as the main component is not included.

The lower limit of the average thickness of the base material layer 2 is preferably 10 μm, more preferably 100 μm. If the average thickness is smaller than the lower limit, the strength of the base material layer 2 becomes insufficient, and it may be difficult to maintain the shape of the base material layer 2. On the other hand, the upper limit of the average thickness of the base material layer 2 can be appropriately set according to the application, and can be, for example, 10 cm.

Examples of the metal include aluminum, aluminum alloys, copper, copper alloys, iron alloys such as iron and stainless steel, and nickel. When the main component of the base material layer 2 is the above metal, the base material layer 2 may be in the form of a foil or a plate.

Examples of the super engineering plastic include polyimide (PI), polyamideimide (PAI), polyetherimide (PEI), polyetheretherketone (PEEK), polyphenylene sulfide (PPS), polyarylate (PAR), and liquid crystal polymer (LCP). ), Polyesulphon (PSF), polyethersulphon (PES) and the like. Among these, as the super engineering plastic, polyimide, polyamide-imide, and a combination thereof are preferable, and polyimide is more preferable from the viewpoint of heat resistance and the like. The above super engineering plastics can be used alone or in combination of two or more.

[Production method]
Next, a method of manufacturing the sliding member of FIG. 1 will be described. The method for manufacturing the sliding member includes an irradiation step of irradiating a sheet body containing a fluororesin as a main component with ionizing radiation at a temperature equal to or higher than the crystal melting point of the fluororesin and an atmosphere of low oxygen, and a sheet after the irradiation step. It includes a groove forming step of forming a plurality of grooves on the outer surface of the body. In addition, the method for manufacturing the sliding member includes a laminating step of laminating the sheet body on one side of the base material layer 2. In the method for manufacturing the sliding member, the arithmetic average roughness Ra of the outer surface of the sheet body obtained in the groove forming step is set to 5 μm or more. The laminating step may be performed before the irradiation step, between the irradiation step and the groove forming step, or after the groove forming step. Hereinafter, a procedure for performing the laminating step before the irradiation step will be described.

In the method for manufacturing the sliding member, after the fluororesin is crosslinked by the irradiation step, a plurality of grooves are formed by the groove forming step so that the arithmetic average roughness Ra of the outer surface of the sheet body becomes equal to or higher than the above lower limit. As a result, the above-mentioned sliding layer 1 can be manufactured. Therefore, the method for manufacturing the sliding member can manufacture a sliding member having excellent slidability and wear resistance.

(Laminating process)
In the laminating step, the base material layer 2 is laminated on one side of a sheet body containing fluororesin as a main component. The method of laminating the base material layer 2 on the sheet body is not particularly limited, and for example, a method of arranging the sheet body and the base material layer 2 facing each other, and a fluororesin dispersion (fluororesin) on the base material layer 2. A method of applying the sheet body to the base material layer 2 by applying the dispersion liquid in which the powder is uniformly dispersed in the dispersion medium and then drying the dispersion medium, as the base material layer 2 on the sheet body. Examples include a method of applying a coating liquid containing a super engineering plastic.

Examples of the dispersion medium of the fluororesin dispersion include a mixed solution of water and an emulsifier, a mixed solution of water and alcohol, a mixed solution of water and acetone, and a mixed solution of water, alcohol and acetone.

Before the laminating step, a primer layer containing a fluororesin as a main component may be formed between the sheet body and the base material layer 2. Further, before the laminating step, the surface of the base material layer 2 on which the sheet body is laminated may be surface-treated. Examples of the surface treatment include roughening by sandblasting, etching, electrolytic polishing, and the like.

Further, when the coating liquid containing super engineering plastic is applied to the sheet body in the laminating step, the coated surface of the sheet body may be treated with liquid ammonia or the like. As a result, it is possible to prevent the coated super engineering plastic from being repelled and to improve the interlayer adhesive strength between the sheet body and the base material layer 2.

(Irradiation process)
In the irradiation step, the fluororesin contained in the sheet body is crosslinked. As a result, the mechanical properties, wear resistance, adhesion to the base material layer 2 and the like of the sheet body are improved.

In the irradiation step, the sheet body is heated to a temperature equal to or higher than the crystal melting point of the fluororesin. The specific heating temperature in the irradiation step is, for example, 270 ° C. or higher when the fluororesin is FEP (crystal melting point temperature: 270 ° C.), and when the fluororesin is PTFE (crystal melting point temperature: 327 ° C.). Is 327 ° C. or higher, and when the fluororesin is PFA (crystal melting point temperature: 304 ° C. or higher and 310 ° C. or lower), it is 310 ° C. or higher. As the lower limit of the heating temperature, a temperature 5 ° C. higher than the melting point temperature of the crystal is preferable. On the other hand, as the upper limit of the heating temperature, a temperature 50 ° C. higher than the crystal melting point temperature is preferable, and a temperature 20 ° C. higher than the crystal melting point temperature is more preferable. By irradiating ionizing radiation under the above conditions, it is possible to promote cross-linking between molecules while suppressing cleavage of the main chain of the fluororesin. In addition, the formation of a chemical bond between the fluororesin and the base material layer 2 can be promoted.

The upper limit of the oxygen concentration in the irradiation step is preferably 100 ppm, more preferably 10 ppm, still more preferably 5 ppm. If the oxygen concentration exceeds the upper limit, there is a risk of decomposition of the fluororesin, oxidation of the base material layer 2, and the like.

The irradiation of the ionizing radiation in the irradiation step is preferably performed from the outer surface side of the sheet body from the viewpoint of suppressing the shielding of the ionizing radiation by the base material layer 2.

Examples of the ionizing radiation include γ-rays, electron beams, X-rays, neutron rays, high-energy ionizing rays and the like. The lower limit of the irradiation dose of ionizing radiation is preferably 10 kGy, more preferably 70 kGy, and even more preferably 200 kGy. On the other hand, as the upper limit of the irradiation dose, 2000 kGy is preferable, 1200 kGy is more preferable, and 400 kGy is further preferable. If the irradiation dose is smaller than the lower limit, the cross-linking reaction of the fluororesin may not proceed sufficiently. On the contrary, when the irradiation dose exceeds the upper limit, the main chain of the fluororesin may be easily cut.

(Groove formation process)
In the groove forming step, a plurality of grooves are formed on the outer surface of the sheet body. By this groove forming step, the sheet body becomes the sliding layer 1 of FIG. 1 having a plurality of grooves 3 on the outer surface. The method for forming a plurality of grooves on the outer surface of the sheet body is not particularly limited, but a hot press method is preferable. Specifically, in the groove forming step, in a state where the sheet body is heated to the glass transition temperature of the fluororesin or higher, a mold or mesh net having a plurality of inverted shapes of the grooves 3 is pressed on the outer surface of the sheet body. do. In the groove forming step, the outer surface shape of the obtained sliding layer 1 can be adjusted by adjusting the surface shapes of the mold and the mesh net. In the groove forming step, it is preferable to adjust the average width, average depth, and average pitch between the adjacent grooves 3 within the above ranges. The press temperature in the groove forming step may be, for example, 200 ° C. or higher and 300 ° C. or lower, although it depends on the glass transition temperature of the fluororesin. The press time in the groove forming step can be, for example, 10 minutes or more and 60 minutes or less. The press pressure in the groove forming step can be, for example, 10 kg / cm ² or more and 30 kg / cm ² or less.

[Other Embodiments]
It should be considered that the embodiments disclosed this time are exemplary in all respects and not restrictive. The scope of the present invention is not limited to the configuration of the above embodiment, but is indicated by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims. NS.

For example, the sliding member may be a single-layer body composed of only the sliding layer as long as the sliding layer forms the outermost layer, and other layers other than the sliding layer and the base material layer may be used. Further, it may be a multilayer body provided. Further, the sliding layer may be formed by coating the base material layer, for example.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

<Manufacturing example 1>
A sheet having an average thickness of 200 μm made of PTFE having a crystal melting point of 327 ° C. was obtained.

<Manufacturing example 2>
The same PTFE sheet as in Production Example 1 was heated to 340 ° C. in a low oxygen atmosphere with an oxygen concentration of 5 ppm or less in a chamber-type heating irradiation furnace, and irradiated with an electron beam using an electron beam accelerator manufactured by NHV Corporation. .. The irradiation conditions were an acceleration voltage of 1160 kV and an irradiation amount of 300 kGy. As a result, the sheet of Production Example 2 was obtained.

[No. 1]
A mesh net made of SUS of # 40 is placed on the outer surface of the sheet of Production Example 2 and hot-pressed at a press temperature of 250 ° C., a press time of 30 minutes, and a press pressure of 17 kg / cm ² to have a plurality of independent grooves on the outer surface. No. 1 sliding member was manufactured. These independent grooves are arranged in a square lattice as a whole, and the grooves extending in the intersecting direction are not connected to each other. Further, the outer surface of the portion of the sliding member surrounded by the plurality of grooves was dome-shaped. No. Table 1 shows the arithmetic average roughness Ra of the outer surface of the sliding member 1 and the average width, average depth, and average interval of the plurality of grooves. The average depth of the plurality of grooves was measured using a digital microscope "VHX5000" manufactured by KEYENCE CORPORATION.

[No. 2]
No. No. 1 except that the mesh net made of SUS of # 60 was used instead of the mesh net of No. 1. By hot-pressing the outer surface of the sheet of Production Example 2 under the same conditions as in No. 1, No. 1 having a plurality of independent grooves on the outer surface. 2 sliding members were manufactured. These independent grooves are arranged in a square lattice as a whole, and the grooves extending in the intersecting direction are not connected to each other. Further, the outer surface of the portion of the sliding member surrounded by the plurality of grooves was dome-shaped. No. Table 1 shows the arithmetic average roughness Ra of the outer surface of the sliding member 2 and the average width, average depth, and average interval of the plurality of grooves.

[No. 3]
No. No. 1 except that the mesh net made of SUS of # 80 was used instead of the mesh net of No. 1. By hot-pressing the outer surface of the sheet of Production Example 2 under the same conditions as in No. 1, No. 1 having a plurality of independent grooves on the outer surface. 3 sliding members were manufactured. These independent grooves are arranged in a square lattice as a whole, and the grooves extending in the intersecting direction are not connected to each other. Further, the outer surface of the portion of the sliding member surrounded by the plurality of grooves was dome-shaped. No. Table 1 shows the arithmetic average roughness Ra of the outer surface of the sliding member of No. 3, the average width of the plurality of grooves, the average depth, and the average interval.

[No. 4]
No. No. 1 except that the mesh net made of SUS of # 200 was used instead of the mesh net of 1. By hot-pressing the outer surface of the sheet of Production Example 2 under the same conditions as in No. 1, No. 1 having a plurality of independent grooves on the outer surface. 4 sliding members were manufactured. These independent grooves are arranged in a square lattice as a whole, and the grooves extending in the intersecting direction are not connected to each other. Further, the outer surface of the portion of the sliding member surrounded by the plurality of grooves was dome-shaped. No. Table 1 shows the arithmetic average roughness Ra of the outer surface of the sliding member of No. 4, the average width of the plurality of grooves, the average depth, and the average interval.

[No. 5]
No. No. 1 except that the mesh net made of SUS of # 20 was used instead of the mesh net of 1. By hot-pressing the outer surface of the sheet of Production Example 2 under the same conditions as in No. 1, No. 1 having a plurality of independent grooves on the outer surface. 5 sliding members were manufactured. These independent grooves are arranged in a square lattice as a whole, and the grooves extending in the intersecting direction are not connected to each other. Further, the outer surface of the portion of the sliding member surrounded by the plurality of grooves was dome-shaped. No. Table 1 shows the arithmetic average roughness Ra of the outer surface of the sliding member No. 5, the average width of the plurality of grooves, the average depth, and the average spacing.

[No. 6]
No. No. 1 except that the mesh net made of SUS of # 10 was used instead of the mesh net of 1. By hot-pressing the outer surface of the sheet of Production Example 2 under the same conditions as in No. 1, No. 1 having a plurality of independent grooves on the outer surface. 6 sliding members were manufactured. These independent grooves are arranged in a square lattice as a whole, and the grooves extending in the intersecting direction are not connected to each other. Further, the outer surface of the portion of the sliding member surrounded by the plurality of grooves was dome-shaped. No. Table 1 shows the arithmetic average roughness Ra of the outer surface of the sliding member No. 6, the average width of the plurality of grooves, the average depth, and the average interval.

[No. 7]
A sliding member made of the sheet of Production Example 1 was obtained. No. Table 1 shows the arithmetic mean roughness Ra of the outer surface of the sliding member of No. 7.

[No. 8]
A sliding member made of the sheet of Production Example 2 was obtained. No. Table 1 shows the arithmetic mean roughness Ra of the outer surface of the sliding member of No. 8.

<Dynamic friction coefficient>
No. 1-No. 4, No. 7, No. A state in which grease is applied to the outer surface of the sliding member with a dynamic friction coefficient at speeds of 10 m / min, 15 m / min, 24 m / min, 38 m / min, 62 m / min and 96 m / min of the sliding member of No. 8 (grease application mode). It was measured by the following measuring method. In addition, No. 1, No. 3 to No. 5, No. 7, No. The coefficient of kinetic friction of the sliding member No. 8 at the above speed was measured by the same measuring method as in the grease application mode in a state where grease was not applied to the outer surface of the sliding member (dry mode). No. in the grease application mode. 1-No. 4, No. The measurement result of No. 8 is shown in FIG. No. in dry mode. 1, No. 3 to No. 5, No. The measurement result of No. 8 is shown in FIG. In addition, No. 1 in the grease application mode. 7 and No. The measurement result of No. 8 is shown in FIG. 7 and No. The measurement result of No. 8 is shown in FIG.
(Measuring method)
The measurement was performed in accordance with JIS-K7218: 1986 Method A (ring-on-disc thrust friction test) under the following conditions.
Ring-shaped mating material Material: S45C
Ring dimensions: outer diameter 41 mm, inner diameter 20 mm
Ring-shaped mating material Arithmetic mean roughness Ra: 0.28 μm
Test equipment: "EFM-III 1010" manufactured by A & D Co., Ltd.
Pressure: 0.1 MPa (constant)
Speed: 10m / min, 15m / min, 24m / min, 38m / min, 62m / min, 96m / min
The film was rotated at each of the above speeds for 10 minutes, and if the film was not torn, the pressure was increased. The pressure was always 0.1 MPa.

<Grease retention>
No. 1-No. The sliding member of No. 8 ^{was cut into a rectangular shape of 36 cm 2} , and the outer surface of the cut sample was sufficiently greased with a finger wearing rubber gloves. Then, using a linear metal scale, the grease adhering to the outer surface of each sample was wiped 5 times each in the direction orthogonal to the outer surface of the sample, and then the residual amount of grease was measured to measure the retention of grease. The measurement result is shown in FIG. Further, FIG. 10 shows the relationship between the arithmetic mean roughness Ra of the outer surface of the sliding member obtained from the above measurement and the remaining amount of grease. In addition, No. in this measurement. 7 and No. The remaining amount of grease per unit area of 8 was the same.

[Evaluation results]
<About grease application mode>
No. which does not have a groove on the outer surface. 7 and No. When No. 8 was compared, as shown in FIG. 7, No. 8 irradiated with an electron beam. No. 8 is not irradiated with an electron beam. The coefficient of dynamic friction is smaller than that of 7. This is No. In No. 8, radicals were generated when the fluororesin was crosslinked by irradiation with an electron beam, and it is considered that the radicals improved the compatibility of grease.

In addition, No. 1 irradiated with an electron beam. 1-No. 4, No. When No. 8 is compared, as shown in FIG. 5, No. 8 having a plurality of grooves on the outer surface. 1-No. No. 4 does not have a plurality of grooves on the outer surface. The coefficient of dynamic friction is smaller than that of 8. In addition, No. 1 having a plurality of grooves on the outer surface. 1-No. When 4 is compared, the larger the arithmetic mean roughness Ra of the outer surface is, the smaller the coefficient of kinetic friction is. It is considered that this is because, as shown in FIGS. 9 and 10, the larger the arithmetic mean roughness Ra of the outer surface is, the higher the retention of grease in the plurality of grooves.

<About dry mode>
No. which does not have a groove on the outer surface. 7 and No. When No. 8 was compared, as shown in FIG. 8, No. 8 not irradiated with an electron beam. No. 7 was irradiated with an electron beam. The coefficient of dynamic friction is smaller than that of 8. This is because when the fluororesin is crosslinked by irradiation with an electron beam, the generation of fluororesin powder due to sliding with the sliding target member is suppressed by improving the wear resistance, so that the fluororesin powder has slidability. This is probably because it is difficult to obtain an improvement effect.

In addition, No. 1 irradiated with an electron beam. 1, No. 3 to No. 5, No. When No. 8 is compared, as shown in FIG. 6, No. 2 has a plurality of grooves on the outer surface and the arithmetic average roughness Ra of the outer surface is 26.0 μm or less. 3 to No. No. 5 does not have a plurality of grooves on the outer surface as the arithmetic mean roughness Ra of the outer surface increases. The coefficient of dynamic friction is smaller than that of 8. It is considered that this is because the larger the arithmetic mean roughness Ra of the outer surface is, the smaller the contact area with the sliding target member is. On the other hand, No. which has a plurality of grooves on the outer surface and the calculated average roughness Ra of the outer surface is 34.5 μm. No. 1 has an outer surface arithmetic mean roughness Ra of 26.0 μm. The coefficient of dynamic friction is larger than 5. It is considered that this is because if the arithmetic average roughness Ra of the outer surface becomes too large, damage such as crushing is likely to occur in the convex portion formed between the grooves, and it is difficult to maintain the initial arithmetic average roughness Ra.

As described above, the slidable member of the present invention is excellent in slidability and abrasion resistance, and is therefore suitable for bearings, engine piston skirts, pump sliding parts, sliding packings, sliding plates for OA equipment, and the like. Used.

1 Sliding layer 2 Base material layer 3 Groove 4 Domed part X Lubricant w Width d Depth l Spacing p Pitch

Claims (4)

Equipped with a sliding layer whose main component is fluororesin
The above fluororesin is crosslinked,
The sliding layer has a plurality of grooves on the outer surface,
The arithmetic mean roughness Ra of the outer surface of the sliding layer is 10 μm or more.
The average width of the plurality of grooves is 100 μm or more and 400 μm or less, the average depth is 100 μm or more and 500 μm or less, and the average interval is 300 μm or more and 5500 μm or less.
A sliding member in which at least a part of the plurality of grooves is an independent groove, and the plurality of grooves are arranged in a grid pattern as a whole and extend in an intersecting direction . The sliding member according to claim 1, wherein the arithmetic average roughness Ra is 35 μm or less. The sliding member according to claim 1 or 2 , wherein the outer surface of the portion of the sliding layer surrounded by the plurality of grooves is formed in a dome shape. An irradiation step of irradiating a sheet body containing a fluororesin as a main component with ionizing radiation at a temperature equal to or higher than the crystal melting point of the fluororesin and in a low oxygen atmosphere.
A groove forming step of forming a plurality of grooves on the outer surface of the sheet body after the irradiation step is provided.
In the groove forming process,
The arithmetic mean roughness Ra of the outer surface of the obtained sheet body is set to 10 μm or more.
The average width of the plurality of grooves is 100 μm or more and 400 μm or less, the average depth is 100 μm or more and 500 μm or less, and the average interval is 300 μm or more and 5500 μm or less.
A method for manufacturing a sliding member, wherein at least a part of the plurality of grooves is an independent groove, and the plurality of grooves are arranged in a grid pattern as a whole and so as to extend in an intersecting direction.

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