JP6977391B2 - Sliding member and its manufacturing method, as well as sliding member for fixing device, fixing device and image forming device - Google Patents

Description

The present invention relates to a sliding member and a method for manufacturing the same, and a sliding member for a fixing device, a fixing device, and an image forming device.

The sliding member has a sliding surface. The sliding member can exhibit various functions by arranging the members other than the sliding member and the sliding surface so as to slide with each other. Image forming devices such as copiers, printers, facsimiles, and multifunction devices are equipped with fixing devices. The sliding member is used, for example, as a sliding member for a fixing device in a fixing device of an image forming device.

The fixing device (so-called pad pressure type fixing device) includes a roller and an endless belt that rotate together facing each other, a pressing member arranged on the inner peripheral surface side of the endless belt, and the pressing member and the endless belt. It is provided with a sliding member for a fixing device arranged between the two. The pressing member presses the endless belt against the roller via the sliding member for the fixing device. A nip portion is formed between the endless belt and the roller. The recording medium is guided to the nip portion, and the toner image on the recording medium is fixed on the recording medium by being heated and pressurized in the nip portion.

In the fixing device having the above configuration, the recording medium comes into contact with the endless belt and the roller as the recording medium passes through the nip portion. The portion of the endless belt that comes into contact with the recording medium (for example, the central portion in the axial direction of the endless belt) is deprived of heat by the recording medium. The portion (end) of the endless belt that does not come into contact with the recording medium is not deprived of heat by the recording medium.

A temperature difference is likely to be formed between the central portion and the end portion in the axial direction of the endless belt. Such temperature differences can affect the useful life of endless belts. Due to the formation of the temperature difference, the end reaches the end of life earlier than the central part in the axial direction of the endless belt, and as a result, the useful life of the endless belt as a whole becomes the end part in the axial direction of the endless belt. It can be rate-determined by the life of the.

The fixing device disclosed in the following Patent Document 1 (Japanese Unexamined Patent Publication No. 2016-099590) has a configuration referred to as a nip forming member. This nip forming member has a heat equalizing member and is arranged so as to be in contact with the inner peripheral surface of the endless belt. Patent Document 1 states that by having the heat equalizing member, the temperature difference between the central portion and the end portion in the axial direction of the endless belt can be reduced. In Patent Document 1, gold, silver, copper, and graphite are mentioned as materials for the heat soaking member.

The fixing device disclosed in Patent Document 2 below (Japanese Unexamined Patent Publication No. 2016-114743) includes a heater member, a first heat transfer member, and a second heat transfer member. The heater member is in contact with the inner peripheral surface of the endless belt via the first heat transfer member, and a second heat transfer member having elasticity is provided between the heater member and the first heat transfer member. In Patent Document 2, copper and aluminum are mentioned as materials for the first heat transfer member. As a material of the second heat transfer member, a graphite sheet having an anisotropic thermal conductivity is mentioned. Patent Document 2 also discloses that surface treatment using a material such as DLC (diamond-like carbon) or PTFE (polytetrafluoroethylene) may be carried out on the first heat transfer member.

In the fixing device disclosed in Patent Document 3 below (Japanese Unexamined Patent Publication No. 07-295409), a fixing heater is arranged so as to slide on the film, and an intermediate layer is provided on the insulating protective film of the fixing heater. A lubrication protective film is formed through the film. Examples of the constitution of the lubrication protective film include a DLC film (diamond-like carbon film) composed of a mixture of diamond crystals, graphite crystals, and amorphous carbon.

Japanese Unexamined Patent Publication No. 2016-099590 Japanese Unexamined Patent Publication No. 2016-114743 Japanese Unexamined Patent Publication No. 07-295409

Graphite (for example, graphite having a carbon purity of 98 atom% or more) has features such as high thermal conductivity and high heat resistance. When graphite is applied to the member constituting the sliding surface of the sliding member, a high heat equalizing effect can be expected. For example, the temperature difference that can occur between the central portion and the end portion in the axial direction of the endless belt can be obtained. Can be made smaller. However, when the sliding surface of the sliding member is composed of graphite itself (for example, a simple substance of graphite having a carbon purity of 98 atom% or more), wear of the sliding surface is likely to proceed, and the sliding member can be used as a sliding member. Not practical.

Here, examples of the type of graphite include anisotropic graphite and isotropic graphite. The thermal conductivity of anisotropic graphite is more than 10 times higher than that of isotropic graphite. Anisotropic graphite has a weak bonding force in the thickness direction and has cleavage property, so that it exhibits low frictional property. Anisotropic graphite has a low coefficient of friction and can also function as a solid lubricant. If anisotropic graphite is used as the sliding member, it can be a sliding member having high heat soaking property.

However, the strength and wear resistance of anisotropic graphite are 1/10 or more weaker than the strength and wear resistance of isotropic graphite, respectively. Therefore, when anisotropic graphite alone is used as a sliding member, wear of the sliding surface tends to proceed, which is not practical as a sliding member. On the other hand, the thermal conductivity of isotropic graphite is lower than that of anisotropic graphite, but is, for example, about 50 to 150 W / m · K, and has the same thermal conductivity as an aluminum alloy. Isotropic graphite is also present.

In recent years, there have been increasing demands for cost reduction and energy saving. In order to meet such demands, the sliding member can exhibit a high heat equalizing effect and can be used for a long period of time by having both high thermal conductivity and high slidability. There is a demand for a sliding member. As described above, Patent Documents 1 to 3 propose that graphite is used to form a sliding member.

Patent Documents 1 and 3 do not specifically describe isotropic graphite or anisotropic graphite. In Patent Document 2, the sliding member is configured by forming a plurality of members into a multi-layer structure to improve the heat soaking property of the sliding member. As a material of the second heat transfer member, a graphite sheet having an anisotropic thermal conductivity is mentioned. When the sliding member is composed of a multi-layer structure composed of a plurality of members as disclosed in Patent Document 2, the adhesion between the members affects the heat soaking property of the sliding member. In order to eliminate the air layer between the members, for example, conductive grease or the like may be applied to the sliding member.

However, the thermal conductivity of the base oil of grease itself is low, and even if the grease contains a filler having high thermal conductivity such as carbon, graphite, and metal, the thermal conductivity of the sliding member and the grease Since there is a large gap with the thermal conductivity, it is difficult to obtain a sufficient heat equalizing effect for the sliding member as a whole. When graphite is used for the sliding member, grease may permeate the graphite and the sliding member may become brittle. When such a sliding member is adopted for a pad-type fixing device that slides under high temperature and high pressure, cracks may occur in graphite, and it is not easy to obtain a sufficient heat equalizing effect.

The present invention was created in view of the above-mentioned circumstances, and by having both high thermal conductivity and high slidability, a high heat equalizing effect can be exhibited and the present invention can be exerted for a long period of time. It is an object of the present invention to provide a sliding member that can be used, and a method for manufacturing the same. It is also an object of the present invention to provide a sliding member for a fixing device capable of realizing such an object, and a fixing device and an image forming device provided with such a sliding member for the fixing device.

The sliding member according to the present invention comprises a base material having a main surface and formed of isotropic graphite, and a coat layer provided on the main surface and constituting the sliding surface. The coefficient of friction of the sliding surface of the layer is lower than the coefficient of friction of the main surface in a state where the coat layer is not provided on the main surface and the main surface is exposed.

In the sliding member, the coat layer is preferably formed from an amorphous carbon film, and the carbon purity of the isotropic graphite is 98 atom% or more.

In the sliding member, the base material is preferably formed of the isotropic graphite and an anisotropic graphite thin layer provided on the isotropic graphite and constituting the main surface.

In the sliding member, preferably, the main surface is composed of the isotropic graphite, and the isotropic isotropic in a state where the coat layer is not provided on the main surface and the main surface is exposed. The surface roughness Ra of the main surface of graphite is less than 1.0.

In the sliding member, a lubricant may be applied to the sliding surface of the coat layer.

In the sliding member, the lubricant may be composed of fluorine grease.

In the sliding member, the lubricant may be composed of silicone oil.

The fixing device sliding member based on the present invention is a fixing device sliding member used in the fixing device, and the fixing device includes a roller and an endless belt that rotate together facing each other and an endless belt. The pressing member arranged on the peripheral surface side and sandwiching the endless belt between the rollers by pressing the endless belt toward the roller, and the pressing member arranged between the pressing member and the endless belt. A sliding member for a fixing device is provided, and the sliding member for a fixing device is the sliding member based on the present invention.

In the sliding member for a fixing device, the thermal conductivity of the isotropic graphite is preferably 100 W / (m · K) or more, and the Young's modulus of the isotropic graphite is 10 GPa or more.

In the sliding member for the fixing device, the thickness of the isotropic graphite is preferably 1 mm or more and 10 mm or less.

The fixing device based on the present invention is configured to include the above-mentioned sliding member for the fixing device based on the present invention.

The image forming apparatus based on the present invention is configured to include the above-mentioned fixing device based on the present invention.

The method for manufacturing a sliding member based on a certain aspect of the present invention is a method for manufacturing a sliding member according to the present invention, wherein the amorphous carbon film is formed on the main surface. It comprises a step of forming by a film.

The method for manufacturing a sliding member based on a certain aspect of the present invention is a method for manufacturing a sliding member according to the present invention, which is a method for manufacturing a sliding member, and has a heat of 1,000 W / (m · K) or more. The above-mentioned step of preparing an anisotropic graphite sheet having conductivity and the above-mentioned by generating a shearing force between them in a state where the heated anisotropic graphite sheet is pressed onto the isotropic graphite. A step of forming the anisotropic graphite thin layer on isotropic graphite is provided.

According to the above configuration, by having both high thermal conductivity and high slidability, it is possible to obtain a sliding member capable of exhibiting a high heat equalizing effect and being able to be used for a long period of time. Can be done.

It is a figure which shows the image forming apparatus 1 in embodiment. It is a figure which shows the fixing device 30 in an embodiment. It is sectional drawing which shows the sliding member 33 (sliding member) for a fixing device in embodiment. FIG. 3 is an enlarged cross-sectional view showing a region surrounded by IV lines in FIG. It is sectional drawing which shows the base material 33a which the coat layer 33b is not provided on the main surface 33s (isotropic graphite) of a base material 33a, and the main surface 33s is exposed. It is sectional drawing which shows the sliding member 33E (sliding member) for a fixing device in the modification of embodiment. FIG. 3 is an enlarged cross-sectional view showing a region surrounded by VII lines in FIG. It is sectional drawing for demonstrating the manufacturing method of the sliding member for a fixing device in the modification of embodiment. It is a figure which shows the verification experiment which concerns on embodiment and the modified example, and the result. It is a figure which shows the specification of the base material A and the intermediate layer A used in the verification experiment which concerns on embodiment and the modified example.

The embodiments will be described below with reference to the drawings. The same parts and equivalent parts may be given the same reference numbers and duplicate explanations may not be repeated. The following embodiments will be described based on the sliding member (that is, the sliding member for the fixing device) applied to the fixing device of the image forming apparatus.

The technical idea as a sliding member disclosed in the following embodiments is not limited to application to a fixing device or an image forming device. The technical idea as a sliding member disclosed in the following embodiments is that the sliding member is configured so that the sliding surface of the sliding member and a member other than the sliding member slide with each other. , Applicable to any technical field.

[Image forming apparatus 1]
FIG. 1 is a diagram showing an image forming apparatus 1 according to an embodiment. The image forming apparatus 1 includes imaging cartridges 10A to 10D, an intermediate transfer belt 21, a fixing apparatus 30, and the like. Each of the imaging cartridges 10A to 10D includes a photoconductor 11, a charging device 12, a latent image forming device 13, a developing device 14, and a cleaning device 15. The developing apparatus 14 of the imaging cartridges 10A to 10D contains, for example, black, yellow, magenta, and cyan toners, respectively.

In each of the imaging cartridges 10A to 10D, the surface of the photoconductor 11 is charged by the charging device 12. The surface of the charged photoconductor 11 is exposed by the latent image forming apparatus 13. An electrostatic latent image corresponding to the image information is formed on the surface of the photoconductor 11. By supplying toner to the electrostatic latent image from the developing device 14, a toner image is formed on the surface of the photoconductor 11.

The intermediate transfer belt 21 is hung on the drive roller 20a and the rotary roller 20b. The toner image formed on the surface of each of the photoconductors 11 of the imaging cartridges 10A to 10D is sequentially transferred onto the intermediate transfer belt 21 at the primary transfer portion between the photoconductor 11 and the primary transfer roller 22. Toner. The toner remaining on the surface of the photoconductor 11 after the transfer is removed from the surface of the photoconductor 11 by the cleaning device 15.

The toner image superimposed on the intermediate transfer belt 21 is conveyed to a position (secondary transfer section) where the intermediate transfer belt 21 and the secondary transfer roller 23 face each other by the circumferential movement of the intermediate transfer belt 21. Toner. The recording medium S housed in the image forming apparatus 1 is guided to a position between the intermediate transfer belt 21 and the secondary transfer roller 23 at an appropriate timing by the paper feed roller 24 and the timing roller 25.

The toner image formed on the intermediate transfer belt 21 is transferred onto the recording medium S at the secondary transfer section between the intermediate transfer belt 21 and the secondary transfer roller 23. The toner remaining on the surface of the intermediate transfer belt 21 after transfer is removed from the surface of the intermediate transfer belt 21 by the cleaning device 26. The recording medium S on which the toner image is transferred is guided to the fixing device 30. The unfixed toner image transferred onto the recording medium S is fixed on the recording medium S in the fixing device 30. The recording medium S on which the toner image is fixed is ejected by the paper ejection roller 27.

[Fixing device 30]
FIG. 2 is a diagram showing a fixing device 30 in the embodiment. The fixing device 30 includes a roller 31, an endless belt 32, a sliding member 33 for the fixing device, a heating roller 34, and a pressing member 35.

The roller 31 has a core metal 31a and an elastic layer 31b. The elastic layer 31b is formed of rubber or sponge and is provided on the outer periphery of the core metal 31a. The roller 31 and the endless belt 32 are arranged so that their outer peripheral surfaces face each other. By rotating the roller 31, the endless belt 32 in contact with the roller 31 also rotates.

The sliding member 33 for the fixing device, the heating roller 34, and the pressing member 35 are arranged on the inner peripheral surface 32s side of the endless belt 32. The fixing device sliding member 33 is arranged between the pressing member 35 and the inner peripheral surface 32s of the endless belt 32, and is in contact with the inner peripheral surface 32s of the endless belt 32. The pressing member 35 presses the endless belt 32 toward the roller 31 via the fixing device sliding member 33. The endless belt 32 is sandwiched between the fixing device sliding member 33 (sliding surface 33t described later) and the outer peripheral surface of the roller 31. A nip portion N is formed between the outer peripheral surface of the roller 31 and the outer peripheral surface of the endless belt 32.

The heating roller 34 is arranged at a position opposite to the roller 31 with respect to the fixing device sliding member 33. Inside the heating roller 34, a heating device 34a such as a halogen lamp is provided. A part of the endless belt 32 is bridged over the heating roller 34 and heated by the heating roller 34. The method of heating the endless belt 32 may be a method of heating the endless belt 32 with an IH or a method of heating the endless belt 32 with a resistance heating element or the like.

The recording medium S on which the toner image t is transferred is inserted into the nip portion N of the fixing device 30, and is heated and pressurized in the nip portion N. As described above, the recording medium S on which the toner image t is fixed is discharged by the paper ejection roller 27 (FIG. 1).

[Sliding member 33 for fixing device]
FIG. 3 is a cross-sectional view showing a sliding member 33 (sliding member) for a fixing device according to an embodiment. FIG. 4 is an enlarged cross-sectional view showing a region surrounded by the IV line in FIG. As shown in FIGS. 2 to 4, the fixing device sliding member 33 includes a base material 33a and a coat layer 33b.

(Base material 33a)
The base material 33a is formed of isotropic graphite and has a main surface 33s. Although details will be described later, a coat layer 33b is provided on the main surface 33s. Isotropic graphite is composed of a plurality of fine particles having a submicron size and exhibits a porous structure.

The carbon purity of isotropic graphite is, for example, 98 atom% or more. When the coat layer 33b is composed of diamond-like carbon (DLC), the carbon purity of the isotropic graphite is 98 atom% or more, so that the base material 33a (isotropic graphite) and the coat layer 33b (diamond-like) are used. The bonding force with carbon) becomes stronger, and the film strength of the coat layer 33b (diamond-like carbon) can be improved.

As shown in FIG. 4, the surface layer portion of isotropic graphite is composed of a plurality of graphite fine particles 33as, and irregularities having a size of several microns are formed. In the present embodiment, the main surface 33s of the base material 33a is composed of isotropic graphite (a plurality of graphite fine particles 33as exhibiting irregularities).

As described above, examples of the type of graphite include anisotropic graphite and isotropic graphite. Anisotropic graphite is generally composed of a thin sheet having a thickness of a dozen μm to a dozen μm. The thermal conductivity of anisotropic graphite in the plane direction is, for example, 1,000 W / m · K to 2,000 W / m · K. On the other hand, the thermal conductivity of anisotropic graphite in the thickness direction is, for example, 1 W / m · K to several tens of W / m · K, which is extremely lower than the thermal conductivity in the plane direction. Anisotropic graphite has characteristics such as weak bonding force in the thickness direction, cleavage property, and easy breakage.

On the other hand, isotropic graphite can be produced so as to have various shapes such as a block shape, a sheet shape, a plate shape, and a semicircular shape. The thermal conductivity of isotropic graphite is lower than that of anisotropic graphite, for example, 50 W / m · K to 150 W / m · K. However, the strength of isotropic graphite is stronger than that of anisotropic graphite, and isotropic graphite is less likely to be damaged than anisotropic graphite.

As the isotropic graphite used for the base material 33a, one having optimum characteristics in terms of thermal conductivity, strength and carbon purity is selected. Considering the soaking property of the base material 33a, the thermal conductivity of isotropic graphite is preferably 100 W / m · K or more. Considering the strength of the base material 33a, the Young's modulus of isotropic graphite is preferably 10 GPa or more. Considering the film strength of the coat layer 33b (diamond-like carbon), the carbon purity of isotropic graphite is preferably 98 atom% or more.

The thickness TH1 (FIG. 3) of the isotropic graphite used for the base material 33a is preferably, for example, 1 mm or more and 10 mm or less in view of the rigidity and heat capacity of the base material 33a. When it is 1 mm or more, the rigidity and bending strength of the base material 33a are likely to be improved, and when it is 10 mm or less, the heat capacity is lowered, so that the thermal conductivity in the plane direction is improved and the heat soaking property is also improved. do. The isotropic graphite thickness TH1 described here is defined by observing the cross section of the sliding member 33 for a fixing device by SEM and specifying the base material 33a, the coat layer 33b, etc. based on the contrast at the interface of each layer. It is a value obtained by measuring the thickness TH1 of the base material 33a (isotropic graphite).

FIG. 5 is a cross-sectional view showing a base material 33a in which the main surface 33s is exposed without the coat layer 33b being provided on the main surface 33s (isotropic graphite) of the base material 33a. Regarding the surface roughness of the base material 33a (isotropic graphite), in a state where the coat layer 33b is not provided on the main surface 33s (isotropic graphite) of the base material 33a and the main surface 33s is exposed (Fig. (In the state shown in 5), the surface roughness Ra of the main surface 33s of the base material 33a (isotropic graphite) is preferably as small as possible from the viewpoint of forming a uniform coat layer 33b, for example, 1.0. Is less than. As mentioned above, isotropic graphite has a porous structure. The surface roughness Ra can be set to less than 3.0 by rough polishing with a milling machine, and the surface roughness Ra can be set to less than 1.0 by further performing honing processing and lapping processing.

For the surface roughness Ra value described here, the cutoff value is set to 0.8 using a surface roughness measuring machine (SURFCOM 480A manufactured by Tokyo Seimitsu Co., Ltd.) (“SURFCOM” is a registered trademark). , Set the measurement points to 10 points, set the measurement length per point to 0.3, measure the surface roughness of the convex part of the main surface 33s, add up the measured data, and set the measurement length to 3 mm. It is a value obtained by calculating Ra as.

The isotropic graphite of the base material 33a capable of having each of the above characteristics is specifically produced from, for example, ISEM-3 (thermal conductivity of 130 W / m · K) manufactured by Toyo Tanso Co., Ltd. It is possible. For example, prepare isotropic graphite with a block-like shape, cut the surface, set the length in the longitudinal direction to 360 mm, set the length in the lateral direction to 20 mm, and set the thickness to 3 mm. do. Of the surface of isotropic graphite, the surface (one side) on the side where the main surface 33s is planned to be formed is roughly polished by milling, and then finish-polished by honing. As a result, the main surface 33s having a surface roughness Ra of less than 1 is formed on the base material 33a. Of the portions of the sliding member 33 for the fixing device that come into contact with the endless belt 32 (FIG. 2), the portion located on the inlet side and the portion located on the outlet side of the base material 33a have a radius of curvature of 5R (5 mm). A curved surface having a

(Coat layer 33b)
With reference to FIGS. 2 to 4, as described above, the coat layer 33b is provided on the main surface 33s of the base material 33a. The surface of the coat layer 33b on the side opposite to the surface bonded to the main surface 33s constitutes the sliding surface 33t of the sliding member 33 for the fixing device. The fixing device sliding member 33 has various functions (for example, the endless belt 32 and the roller 31) by arranging the members other than the fixing device sliding member 33 and the sliding surface 33t so as to slide with each other. It is possible to exert the function of forming the nip portion N between the and.

In the fixing device sliding member 33, the sliding surface 33t is not composed of the main surface 33s of the base material 33a (isotropic graphite), but is composed of the surface of the coat layer 33b. The friction coefficient of the sliding surface 33t of the coat layer 33b is the friction coefficient of the main surface 33s in a state where the coat layer 33b is not provided on the main surface 33s and the main surface 33s is exposed (the state shown in FIG. 5). Lower than. The friction coefficient of the sliding surface 33t referred to here is the friction coefficient of the sliding surface 33t in a state where the lubricant described later is not applied to the sliding surface 33t. The coefficient of friction of the sliding surface 33t of the coat layer 33b is, for example, 0.1 or less, and the main surface 33s is exposed without the coat layer 33b being provided on the main surface 33s (state shown in FIG. 5). The coefficient of friction of the main surface 33s in the above is, for example, about 0.2.

The low-friction coat layer 33b capable of exhibiting such characteristics can be formed from, for example, an amorphous carbon film also known as diamond-like carbon (DLC). The coat layer 33b can also be formed from a fluororesin such as _{molybdenum disulfide (MoS 2} ), tungsten disulfide (WS _{2), and PTFE.} The coat layer 33b is preferably formed of an amorphous carbon film (DLC) among them. The amorphous carbon film (DLC) can exhibit good filmability with carbon (base material 33a), has excellent wear resistance, and is compatible with both dry and oil lubrication.

(Amorphous carbon film (DLC))
In the present embodiment, the amorphous carbon film used as the material of the coat layer 33b has heat resistance, low friction, high hardness, and thermal conductivity, and can be paraphrased as DLC (diamond-like carbon). can.

The DLC has a structure having a diamond structure (sp3 type crystal) partially in the graphite structure (sp2 type crystal), and has a low coefficient of friction and a high wear resistance. When the sliding surface 33t of the fixing device sliding member 33 (coat layer 33b) and the inner peripheral surface 32s of the endless belt 32 are in mutual contact with each other and they move relatively, between them. Shear force is generated. By using a material having a low coefficient of friction (here, DLC) as a component of the coat layer 33b, it is possible to reduce the value of the shear force generated between them.

The thickness TH2 (FIG. 3) of the coat layer 33b is preferably 0.5 μm or more and 5 μm or less, for example. When it is 0.5 μm or more, good thermal conductivity in the plane direction can be obtained, the heat capacity does not become too small, the desired heat equalizing effect can be easily obtained, and the wear resistance does not deteriorate. When it is 5 μm or less, the heat capacity does not become too large, the thermal conductivity in the plane direction does not decrease too much, and the desired heat equalizing effect can be easily obtained. The non-uniform formation of the film is also suppressed, and the strength is not reduced and the wear resistance is not reduced.

Regarding the method for manufacturing the sliding member 33 for a fixing device, the amorphous carbon film as the coat layer 33b can be formed by forming a film on the main surface 33s of the base material 33a. For example, the UBM (UnBalanced Magnetoron) sputtering method is used to coat the entire surface layer of the base material 33a with a DLC film. At this time, for example, using a UBM sputtering source (target: carbon) having a diameter of 6 inches, the Ar gas pressure is set to 0.4 Pa, the input DC power is set to about 6 W / cm ² , and the film forming speed is set to about. The DLC film is formed so that the film thickness is set to 30 nm / min, the substrate bias voltage is applied in the range of 0 to 200 V, and the film thickness is about 2 μm. The coat layer 33b obtained by this method has a surface roughness (Ra) of, for example, 0.5 after DLC film formation.

The coat layer 33b may be formed only on the main surface 33s of the base material 33a formed of isotropic graphite, or may be formed on the main surface 33s of the base material 33a and the main surface on the opposite side thereof (relative to the base material 33a). It may be formed on both the main surface located on the pressing member 35 side), or it may be formed on the entire outer surface of the base material 33a.

When the lubricant described below is applied to the sliding surface 33t of the coat layer 33b, the lubricant penetrates into isotropic graphite by forming the coat layer 33b on the entire outer surface of the base material 33a. This makes it possible to secure sufficient strength of isotropic graphite. By preventing the lubricant from penetrating into isotropic graphite, it is possible to suppress the depletion of the lubricant on the sliding surface 33t (sliding portion).

(lubricant)
A lubricant may be applied to the sliding surface 33t of the coat layer 33b. As described above, a shearing force is generated between the sliding surface 33t of the sliding member 33 for the fixing device (coat layer 33b) and the inner peripheral surface 32s of the endless belt 32. The presence of the lubricant reduces the value of the shearing force, further reduces the coefficient of friction of the sliding surface 33t with respect to the inner peripheral surface 32s, and improves the wear resistance of the sliding member 33 for the fixing device and the endless belt 32. Therefore, it is possible to further extend the service life of these members.

As the lubricant, general-purpose grease or general-purpose oils such as fluorine grease, silicone grease, fluorine oil, silicone oil, and mineral oil can be used. Among these, silicone oil is particularly suitable for improving the low frictional property of the sliding surface 33t, and fluorine grease is suitable for suppressing the depletion of the lubricant on the sliding surface 33t.

If silicone oil is used, the coefficient of friction of the sliding surface 33t with respect to the inner peripheral surface 32s can be significantly reduced as compared with the fluorine grease. The viscosity of the silicone oil gradually decreases due to thermal oxidative decomposition, and there is a possibility that the silicone oil is gradually scraped off from the interface between the sliding surface 33t and the inner peripheral surface 32s. When the sliding member 33 for a fixing device is used for a long period of time, fluorine grease is more preferably used than silicone oil. Compared to silicone oil, fluorine grease has a higher coefficient of friction due to its higher viscosity, but even if it is used for a long period of time, there is almost no change in viscosity, so oil depletion is unlikely to occur, and it is assumed that it has been used for a long time. Can also show stable torque performance.

(Action and effect)
The sliding member 33 for a fixing device in the present embodiment includes a base material 33a and a coat layer 33b, the base material 33a is formed of isotropic graphite, and the coat layer 33b is the main surface 33s of the base material 33a. The sliding surface 33t is provided on the surface, and the coefficient of friction of the sliding surface 33t of the coat layer 33b is such that the coat layer 33b is not provided on the main surface 33s and the main surface 33s is exposed. It is lower than the coefficient of friction of the main surface 33s.

The strength of isotropic graphite is stronger than that of anisotropic graphite, and isotropic graphite is less likely to be damaged than anisotropic graphite. The thermal conductivity of isotropic graphite is lower than that of anisotropic graphite, but it is, for example, 50 W / m · K to 150 W / m · K, and sufficient heat soaking property can be exhibited. The base material 33a is formed of inexpensive and lightweight isotropic graphite having such characteristics, and a coat layer 33b having the above-mentioned characteristics is provided on the main surface 33s of such a base material 33a. Since the coat layer 33b has low friction and wear resistance, the sliding member 33 (sliding member) for a fixing device having the above configuration has high thermal conductivity and high sliding as a whole. By having both motility and motility, it is possible to exert a high heat equalizing effect and to be used for a long period of time.

In the fixing device sliding member 33 of the present embodiment, the coat layer 33b is formed of an amorphous carbon film (DLC), and the carbon purity of the isotropic graphite constituting the base material 33a is 98 atom% or more. Is. That is, the base material 33a is formed of isotropic graphite having a certain degree of strength and abrasion resistance, and has high thermal conductivity, high slidability, and high abrasion resistance on its main surface 33s. An amorphous carbon film, so-called diamond-like carbon (DLC), is coated.

According to such a sliding member 33 for a fixing device, for example, it is possible to exhibit strength that can sufficiently meet the life required as a specification of the fixing device 30, and also to have high heat soaking property and high sliding property. It is possible to have both. Even when a temperature difference is formed between the central portion and the end portion in the axial direction of the endless belt 32, the temperature difference can be effectively reduced by the sliding member 33 for the fixing device.

When DLC is coated on a metal such as aluminum or iron, there may be a problem in terms of film strength. On the other hand, when DLC is coated on isotropic graphite having a carbon purity of 98% or more (almost 100%), a strong coat layer 33b is formed on the main surface 33s by the bonds between the carbon elements. , A dramatic improvement in wear resistance can be expected.

(Use as a heater)
The sliding member 33 for the fixing device can also be used as a heater. The carbon purity of the base material 33a contained in the sliding member 33 for the fixing device is approximately 100%, which indicates electrical conductivity. By applying a voltage to the base material 33a, Joule heat is generated, and the temperature of the sliding surface 33t can be effectively raised. The electrical resistivity of the isotropic graphite (base material 33a) is, for example, 10.0 μΩ · m. Since the electrical resistance of isotropic graphite is relatively low and the thermal efficiency is not so high, when the sliding member 33 for the fixing device is used as a heater, it is used as an auxiliary heater rather than as a main heater in the fixing device 30. Is preferable.

[Modified example of the embodiment]
(Sliding member 33E for fixing device)
The sliding member 33E for a fixing device in the modified example of the embodiment will be described with reference to FIGS. 6 to 8. FIG. 6 is a cross-sectional view showing a sliding member 33E (sliding member) for a fixing device. FIG. 7 is an enlarged cross-sectional view showing a region surrounded by the VII line in FIG. FIG. 8 is a cross-sectional view for explaining a method of manufacturing the sliding member 33E for a fixing device. The fixing device sliding member 33E in this modification and the fixing device sliding member 33 in the above-described embodiment are different in the following points.

In the sliding member 33E for the fixing device, the base material 33a is formed of the isotropic graphite 33a1 and the anisotropic graphite thin layer 33a2. The anisotropic graphite thin layer 33a2 is provided on the isotropic graphite 33a1 (a plurality of graphite fine particles 33as formed on the surface layer portion of the isotropic graphite 33a1), and constitutes the main surface 33s of the base material 33a. is doing. A coat layer 33b is provided on the main surface 33s by the same method as that of the above-described embodiment.

The anisotropic graphite thin layer 33a2 functions as a so-called intermediate layer. An anisotropic graphite thin layer 33a2 is formed as an intermediate layer between the isotropic graphite 33a1 and the coat layer 33b (for example, DLC). According to this configuration, the smoothness of the main surface 33s of the base material 33a is enhanced, and the coat layer 33b can be formed more uniformly on the main surface 33s of the base material 33a, and as a result, the coating strength is further increased. , Further improvement of wear resistance can be expected.

With reference to FIG. 8, as a method for producing the base material 33a by forming the anisotropic graphite thin layer 33a2 on the surface of the isotropic graphite 33a1 (graphite fine particles 33as), pressure and heat are used. , An anisotropic graphite thin layer 33a2 (intermediate layer) can be easily formed on the surface of the isotropic graphite 33a1.

As shown in FIG. 8, for example, anisotropic graphite having an isotropic graphite 33a1 formed in a plate shape and having a thermal conductivity of 1,000 W / (m · K) or more on the surface of the isotropic graphite 33a1. A sheet 33a5 (25 μm) is placed, and in this state, these are pressed against an endless belt under the conditions of 1 MPa, 200 ° C., and 200 mm / s for 30 minutes. In a state where the heated anisotropic graphite thin layer 33a2 is pressed onto the isotropic graphite 33a1, a shearing force is generated between them. Then, by peeling off the anisotropic graphite sheet 33a5 remaining on the isotropic graphite 33a1, the anisotropic graphite thin layer 33a2 is formed on the isotropic graphite 33a1.

The mechanism by which the anisotropic graphite thin layer 33a2 is formed on the surface of the isotropic graphite 33a1 is due to the carbon-carbon bonds (bonds between unpaired electrons in the sP2 hybrid orbital), which is the so-called "metal bond". It is considered that a strong film is formed by a phenomenon similar to "kajiri".

By observing the cross-sectional shape of the obtained base material 33a using SEM, the existence of the anisotropic graphite thin layer 33a2 formed on the surface of the isotropic graphite 33a1 can be confirmed, and the anisotropic graphite can be confirmed. It can also be confirmed that the thickness of the thin layer 33a2 is, for example, about 0.1 μm to 0.5 μm. By forming the anisotropic graphite thin layer 33a2 as an intermediate layer on the surface of the isotropic graphite 33a1, the surface smoothness and the thermal conductivity of the surface are improved, and the base material 33a and the coat layer 33b (DLC or the like) are formed. It is possible to improve the bondability of graphite.

The isotropic graphite 33a1 has a porous shape, and its surface layer portion is composed of a plurality of anisotropic graphite thin layers 33a2 having a submicron size. The surface layer portion of the isotropic graphite 33a1 is formed with irregularities having a size of several microns. By finishing the surface of the isotropic graphite 33a1, the surface of the isotropic graphite 33a1 is smoothed to such an extent that the surface roughness Ra is less than 1.

By forming the anisotropic graphite thin layer 33a2 on the surface of the smoothed isotropic graphite 33a1, the submicron level unevenness existing on the surface of the isotropic graphite 33a1 is removed from the anisotropic graphite thin layer. It is covered with 33a2. This improves the smoothness of the main surface 33s of the base material 33a.

In order to form the anisotropic graphite thin layer 33a2 capable of having each of the above characteristics on the surface of the isotropic graphite 33a1, specifically, for example, an anisotropic graphite sheet manufactured by Kaneka Corporation " "Graphite" can be used. In this anisotropic graphite sheet, the thermal conductivity in the plane direction is set to, for example, 1,500 W / (m · K), and the thickness is set to 0.025 mm.

Such an anisotropic graphite sheet is placed on the surface of the isotropic graphite 33a1. These are pressed against a PI endless belt set at a temperature of 200 ° C. and rotating at a speed of 200 mm / s at a pressure of 1 MPa for 30 minutes. As a result, a part of the anisotropic graphite sheet adheres to the main surface 33s of the base material 33a. By peeling off the excess anisotropic graphite sheet with a brush, the base material 33a in which the anisotropic graphite thin layer 33a2 is formed on the surface of the isotropic graphite 33a1 can be obtained.

[Verification experiment]
With reference to FIGS. 9 and 10, verification experiments performed with respect to the above-described embodiment and variations thereof will be described. The verification experiment includes Examples 1 to 3 and Comparative Example (FIG. 9).

(Experimental conditions)
Here, each sliding member (see FIG. 9) based on Examples 1 to 3 and Comparative Example was prepared. The detailed specifications of the base material A and the intermediate layer A shown in FIG. 9 are as shown in FIG.

The base material A has an isotropic graphite block, a product name of ISEM-3 (manufactured by Toyo Tanso Co., Ltd.), a thickness of 3 [mm], and a finished surface roughness Ra of less than 1. , The density is 1.85 [g / cm ³ ], the electrical resistivity is 10.0 [μΩ · m], the bending strength is 49 [MPa], and the tensile strength is 29 [MPa]. , The linear expansion coefficient is 5.0 [ ^10-6 / K], and the thermal conductivity λ is 130 [W / (m · K)].

The material of the intermediate layer A is an anisotropic graphite sheet, the product name is Graphinity (manufactured by Kaneka), the thickness is 0.025 [mm], and the density is 2.0 [g / cm ³ ]. The tensile strength is 40 [MPa], and the thermal conductivity λ (thermal conductivity λ in the plane direction) is 1500 [W / (m · K)].

Each sliding member (see FIG. 9) based on Examples 1 to 3 is attached to the sliding portion of the "biaxial belt pad fixing tester" having the same configuration as the fixing device 30 shown in FIG. The thermal properties, slidability, and durability were evaluated. A comparative example was evaluated using a PTFE-based sliding member that is standard equipment in a fixing device of "magicolor (registered trademark) 4750DN" manufactured by Konica Minolta.

(Evaluation conditions for soaking property)
The drive speed of the "two-axis belt pad fixing tester" is set to 240 [mm / s], the fixing temperature is set to 160 [° C], the nip load is set to 250 [N], and the nip width is 10 [. It was set to [mm]. While driving the fixing device under the above conditions, the end temperature T1 and the center temperature T2 of the endless belt 32 (fixing belt) when 200 sheets of A6 size paper are passed in the vertical direction are measured, and the temperature thereof is measured. The difference (ΔT) was calculated. The calculation results are shown in FIGS. 9 as Examples 1 to 3 and Comparative Examples.

(Evaluation conditions for slidability and durability)
For each of the sliding members (see FIG. 9) based on Examples 1 to 3 and Comparative Example, the lubricant shown in FIG. 9 has the same configuration as the fixing device 30 shown in FIG. It was attached to the sliding part of the "tester", and the rotation torque was measured every predetermined running time to evaluate the idle rotation durability. At this time, the drive speed of the "two-axis belt pad fixing tester" is set to 240 [mm / s], the fixing temperature is set to 160 [° C], the nip load is set to 250 [N], and the nip width is set. Was set to 10 [mm]. The drive mode was set to so-called 10on2off, in which the drive mode was stopped for 2 seconds every 10 seconds. The evaluation results are shown in FIGS. 1 to 3 and 9 as comparative examples.

(inspection result)
In Examples 1 to 3, the temperature difference ΔT, which is an index related to heat equalization, was 40 [° C.] or less, and a high heat equalization effect was confirmed. In terms of slidability and durability, the rotational torque was 0.3 [Nm] or less even when the traveling time was 2K hours, showing stable low slidability.

On the other hand, in the comparative example, the temperature difference ΔT was 70 ° C., the end temperature of the endless belt 32 (fixing belt) was high, and the heat soaking property was lower than that of Examples 1 to 3. Regarding slidability and durability, the evaluation was discontinued because the rotational torque suddenly increased to 0.8 [Nm] when the mileage was 1K hours, and then the belt end was damaged.

According to the above results, according to Examples 1 to 3 based on the above-described embodiment and its modified examples, a high heat equalizing effect can be exhibited by having both high thermal conductivity and high slidability. It can be seen that a sliding member that can be used for a long period of time can be obtained.

Although the embodiments and modifications and the verification experiments relating to the embodiments have been described above, the above disclosure contents are exemplary in all respects and are not limiting. The technical scope of the present invention 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.

1 Image forming device, 10A, 10B, 10C, 10D Imaging cartridge, 11 Photoreceptor, 12 Charging device, 13 Latent image forming device, 14 Developing device, 15, 26 Cleaning device, 20a drive roller, 20b rotating roller, 21 Intermediate transfer Belt, 22 Primary transfer roller, 23 Secondary transfer roller, 24 Feed roller, 25 Timing roller, 27 Paper ejection roller, 30 Fixing device, 31 Roller, 31a core metal, 31b Elastic layer, 32 Endless belt, 32s Inner peripheral surface , 33, 33E Sliding member for fixing device (sliding member), 33a base material, 33a1 isotropic graphite, 33a2 square graphite thin layer, 33a5 square graphite sheet, 33as graphite fine particles, 33b coat layer, 33s main surface , 33t sliding surface, 34 heating roller, 34a heating device, 35 pressing member, N nip part, S recording medium, TH1, TH2 thickness, t toner image.

Claims (13)

With a substrate having a main surface and made of isotropic graphite,
A coat layer provided on the main surface and constituting the sliding surface is provided.
Friction coefficient of the sliding surface of the coating layer, the coating layer is rather low than the friction coefficient of the main surface in a state where the main surface is exposed without being provided on said main surface,
The base material is formed of the isotropic graphite and an anisotropic graphite thin layer provided on the isotropic graphite and constituting the main surface.
Sliding member. With a substrate having a main surface and made of isotropic graphite,
A coat layer provided on the main surface and constituting the sliding surface is provided.
The coefficient of friction of the sliding surface of the coat layer is lower than the coefficient of friction of the main surface in a state where the coat layer is not provided on the main surface and the main surface is exposed.
The main surface is composed of the isotropic graphite.
In a state where the main surface is exposed without the coat layer being provided on the main surface, the surface roughness Ra of the main surface of the isotropic graphite is less than 1.0.
Sliding member. With a substrate having a main surface and made of isotropic graphite,
A coat layer provided on the main surface and constituting the sliding surface is provided.
The coefficient of friction of the sliding surface of the coat layer is lower than the coefficient of friction of the main surface in a state where the coat layer is not provided on the main surface and the main surface is exposed.
A lubricant was applied to the sliding surface of the coat layer.
Sliding member. The coat layer is formed of an amorphous carbon film and is formed from an amorphous carbon film.
The carbon purity of the isotropic graphite is 98 atom% or more.
The sliding member according to any one of claims 1 to 3. The lubricant is fluorine grease,
The sliding member according to claim 3. The lubricant is a silicone oil.
The sliding member according to claim 3. A sliding member for a fixing device used in a fixing device.
The fixing device is arranged on the inner peripheral surface side of the endless belt and a roller and an endless belt that rotate together facing each other, and by pressing the endless belt toward the roller, the endless belt is pressed against the roller. A pressing member sandwiched between the pressing member and a sliding member for a fixing device arranged between the pressing member and the endless belt are provided.
The fixing device sliding member is the sliding member according to any one of claims 1 to 6 . The thermal conductivity of the isotropic graphite is 100 W / (m · K) or more.
The Young's modulus of the isotropic graphite is 10 GPa or more.
The sliding member for a fixing device according to claim 7. The thickness of the isotropic graphite is 1 mm or more and 10 mm or less.
The sliding member for a fixing device according to claim 7 or 8. The sliding member for a fixing device according to any one of claims 7 to 9 is provided.
Fixing device. The fixing device according to claim 10 is provided.
Image forming device. A method for manufacturing a sliding member according to claim 1, wherein the sliding member is manufactured.
The process of preparing an anisotropic graphite sheet having a thermal conductivity of 1,000 W / (m · K) or more, and
The anisotropic graphite thin layer is formed on the isotropic graphite by generating a shearing force between them in a state where the heated anisotropic graphite sheet is pressed onto the isotropic graphite. With the process of
Manufacturing method of sliding member. A sliding member for a fixing device used in a fixing device.
The fixing device is arranged on the inner peripheral surface side of the endless belt and a roller and an endless belt that rotate together facing each other, and by pressing the endless belt toward the roller, the endless belt is pressed against the roller. A pressing member sandwiched between the pressing member and a sliding member for a fixing device arranged between the pressing member and the endless belt are provided.
The sliding member for the fixing device is
With a substrate having a main surface and made of isotropic graphite,
A coat layer provided on the main surface and constituting the sliding surface is provided.
The coefficient of friction of the sliding surface of the coat layer is lower than the coefficient of friction of the main surface in a state where the coat layer is not provided on the main surface and the main surface is exposed.
Sliding member for fixing device.

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