Lubricating composition, fixing device, and image forming apparatus

Abstract

To provide a lubricating composition which offers high thermal conductivity and low friction.SOLUTION: A lubricating composition is provided, containing a lubricant oil and an aggregate consisting of a plurality of intertwining fibrous carbons.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a lubricating composition, a fixing device, and an image forming apparatus.

Background Art

[0002] Thermal conductive materials are used in various fields.

[0003] For example, Patent Document 1 discloses "a high-rigidity and high-thermal-conductivity fixing belt having a coating layer with releasability on the outer peripheral surface of a thin metal endless belt with a thickness of 10 to 35 μm and a resin layer on the inner peripheral surface." And Patent Document 1 also discloses containing a thermal conductive material in the resin layer.

[0004] Further, Patent Document 2 discloses "a fixing belt having a three-layer structure including an inner layer formed of a resin composition containing a heat-resistant resin and an insulating inorganic filler with an average particle diameter of 0.5 to 15 μm, an outer layer formed of a resin composition containing a fluororesin and a conductive filler, and an intermediate layer formed of a resin composition containing a resin having adhesiveness to both resins of the inner layer and the outer layer and a conductive filler."

[0005] Also, Patent Document 3 discloses "a composite tubular body including a tubular inner layer made of a polyimide resin containing a thermal conductive inorganic powder and a tubular outer layer made of a fluororesin, and a conductive adhesive layer is formed between the tubular inner layer and the tubular outer layer, and the fluororesin constituting the tubular outer layer contains a thermal conductive inorganic powder."

[0006] Further, Patent Document 4 discloses "a polyimide molding for fixing or transfer fixing, which contains 30 to 250 parts by weight of an inorganic filler with respect to 100 parts by weight of a polyimide resin obtained by adding an imidization accelerator and then heating and baking, and has a thermal conductivity of 0.30 W / (m·K) or more."

[0007] When a sliding portion is provided on the inner peripheral surface of a belt or the like described in Patent Documents 1 to 4, it is also known to use a lubricating oil.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0009] An object of the present invention is to provide a lubricating composition having a higher thermal conductivity and higher lubricity than a lubricating composition containing only fibrous carbon that is not intertwined with each other as a heat conductive material, together with a lubricating oil.

Means for Solving the Problems

[0010] Specific means for solving the above problems include the following aspects. <1> A lubricating composition comprising a lubricating oil and an aggregate in which a plurality of fibrous carbons are intertwined with each other. <2> The lubricating composition according to <1>, wherein the fibrous carbon is a carbon nanotube. <3> The lubricating composition according to <1> or <2>, wherein the maximum diameter of the aggregate is 5 μm or more and 100 μm or less. <4> The lubricating composition according to <3>, wherein the maximum diameter of the aggregate is 20 μm or more and 80 μm or less. <5> The lubricating composition according to any one of <1> to <4>, wherein the ratio of the major axis Y to the minor axis X of the aggregate (aspect ratio = major axis Y / minor axis X) is 30 or more and 200 or less. <6> The lubricating composition according to any one of <1> to <5>, wherein the content of the aggregate is 5% by mass or more and 50% by mass or less with respect to the lubricating oil. <7> The lubricating composition according to <6>, wherein the content of the aggregate is 10% by mass or more and 40% by mass or less with respect to the lubricating oil. <8> The lubricating composition according to any one of <1> to <7>, comprising at least one selected from the group consisting of silicone oil and perfluoropolyether as the lubricating oil. <9> The lubricating composition according to <8>, wherein the silicone oil is an amino-modified silicone oil. <10> The lubricating composition according to <8> or <9>, further comprising a fluorosurfactant when the lubricating oil contains perfluoropolyether. <11> A first rotating body, A second rotating body disposed in contact with the first rotating body, A pressing member disposed on the inner surface of the second rotating body and pressing the second rotating body against the first rotating body from the inner surface of the second rotating body, A sliding member interposed between the inner surface of the second rotating body and the pressing member, The lubricating composition according to any one of <1> to <10> interposed between the inner surface of the second rotating body and the sliding member, And a fixing device. <12> An image carrier, A latent image forming device for forming a latent image on the surface of the image carrier, A developing device for developing the latent image into a toner image using a developer, A transfer device for transferring the toner image developed on a recording medium, The fixing device according to <11> for fixing the toner image on the recording medium, And an image forming apparatus.

Advantages of the Invention

[0011] According to the invention according to <1> or <2>, compared with a lubricating composition containing only fibrous carbon not intertwined with each other as a heat conductive material together with a lubricating oil, a lubricating composition having a high thermal conductivity and high lubricity is provided.

[0012] According to the invention according to <3>, compared with the case where the maximum diameter of the aggregate is less than 5 μm or more than 100 μm, a lubricating composition having a high thermal conductivity and high lubricity is provided. According to the invention according to <4>, compared with the case where the maximum diameter of the aggregate is less than 20 μm or more than 80 μm, a lubricating composition having a high thermal conductivity and high lubricity is provided. According to the invention according to <5>, compared with the case where the ratio of the major axis Y to the minor axis X of the aggregate (aspect ratio = major axis Y / minor axis X) is less than 30, a lubricating composition having a high thermal conductivity and high lubricity is provided.

[0013] According to the invention according to <6>, compared with the case where the content of the aggregate is less than 5% by mass or more than 50% by mass with respect to the lubricating oil, a lubricating composition having a high thermal conductivity and high lubricity is provided. According to the invention according to <7>, compared with the case where the content of the aggregate is less than 10% by mass or more than 40% by mass with respect to the lubricating oil, a lubricating composition having a high thermal conductivity and high lubricity is provided.

[0014] According to the invention according to <8>, compared with a lubricating composition containing only fibrous carbon not intertwined with each other as a heat conductive material together with a lubricating oil, as the lubricating oil, at least one selected from the group consisting of silicone oil and perfluoropolyether is included, and a lubricating composition having a high thermal conductivity and high lubricity is provided. According to the invention according to <9>, compared with the case where the silicone oil is dimethyl silicone oil, a lubricating composition having a high thermal conductivity and high lubricity is provided. According to the invention related to <10>, when a lubricating oil contains perfluoropolyether, a lubricating composition having a higher thermal conductivity and higher lubricity is provided as compared with the case where it does not contain a fluorosurfactant.

[0015] According to the invention related to <11>, compared with the case where a lubricating composition containing only fibrous carbon not intertwined with each other as a heat conductive material is applied together with a lubricating oil, an image density unevenness is suppressed and a fixing device that suppresses wrinkles of a recording medium is provided. According to the invention related to <12>, compared with the case where a lubricating composition containing only fibrous carbon not intertwined with each other as a heat conductive material is applied together with a lubricating oil, an image density unevenness is suppressed and an image forming apparatus including a fixing device that suppresses wrinkles of a recording medium is provided.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0017] Hereinafter, embodiments which are examples of the present invention will be described. These descriptions and examples are illustrative of the embodiments and do not limit the scope of the invention. In the numerical ranges described step by step in this specification, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of another numerically described range. Further, in the numerical ranges described in this specification, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples.

[0018] Each component may contain a plurality of corresponding substances. When referring to the amount of each component in a composition, in the case where there are multiple substances corresponding to each component in the composition, unless otherwise specified, it means the total amount of the multiple substances present in the composition.

[0019] When describing embodiments with reference to the drawings, members having substantially the same function are given the same reference numeral throughout the drawings, and duplicate descriptions may be omitted.

[0020] <Lubricating composition> The lubricating composition according to the present embodiment includes a lubricating oil and an aggregate formed by a plurality of fibrous carbons intertwined with each other (hereinafter, also referred to as a "specific aggregate").

[0021] Due to the above configuration, the lubricating composition according to the present embodiment becomes a lubricating composition having high thermal conductivity and high lubricity. The reason is presumed as follows.

[0022] Since the lubricating composition contains a specific aggregate as a heat conduction material together with the lubricating oil, the thermal conductivity of the lubricating composition is likely to be high. Since the specific aggregate can conduct heat radially starting from the intertwined portion of the fibrous carbons (i.e., the portion where the fibrous carbons are in contact with each other), it is considered that higher heat conduction can be obtained compared to the case where it contains fibrous carbons that are not intertwined with each other.

[0023] In addition, since the specific aggregate is an aggregate in which a plurality of fibrous carbons are intertwined with each other and has a rounded shape, an increase in frictional resistance due to the heat conduction material in the sliding portion is suppressed compared to the case where it contains fibrous carbons that are not intertwined with each other. Therefore, it is considered that the lubricity is improved.

[0024] In addition, since the specific aggregate is an aggregate in which a plurality of fibrous carbons are intertwined with each other, lubricating oil is retained inside. The lubricating oil retained inside the specific aggregate is likely to ooze out due to pressure, heat, etc. Therefore, it is considered that the lubricating oil is likely to be interposed in the sliding portion, and the lubricity is improved.

[0025] From the above, it is presumed that the lubricating composition according to the present embodiment is a lubricating composition having high thermal conductivity and high lubricity.

[0026] In particular, the lubricating composition according to the present embodiment has high thermal conductivity, high temperature uniformity, and is less likely to cause local temperature rise. Further, for example, even when a temperature difference occurs between the lubricating compositions present in the sliding portion, the temperature difference is less likely to increase between the lubricating compositions present in the sliding portion. As a result, the generation of a difference in frictional resistance due to non-uniformity of the viscosity of the lubricating oil is also reduced. Therefore, when the lubricating composition according to the present embodiment is applied to a fixing device, for example, even when a toner image is continuously fixed on a recording medium, it is less likely that the temperature of the lubricating composition in the non-passing portion of the recording medium will rise. A temperature difference occurs between the passing portion of the recording medium and the non-passing portion of the recording medium, and the generation of a difference in frictional resistance is suppressed. As a result, when a toner image is continuously fixed on a recording medium, wrinkles on the recording medium caused by the difference in frictional resistance are also suppressed. Further, after continuously fixing a toner image on a recording medium, when a toner image is fixed on recording media of different sizes, deterioration of the recording medium conveyance property due to the difference in frictional resistance that occurs between the passing portion of the recording medium and the non-passing portion of the recording medium in the previous fixing is also suppressed. In addition, since the specific aggregate is an aggregate in which a plurality of fibrous carbons are intertwined with each other, it is easily deformed by pressure. Therefore, when the lubricating composition according to the present embodiment is applied to a fixing device, generation of pressure unevenness due to the heat conductive material is suppressed in the fixing portion. As a result, generation of unevenness in image density of an image due to pressure unevenness is also suppressed.

[0027] Note that since the specific aggregate has a property of being easily deformed by pressure, the lubricating composition according to the present embodiment also suppresses the occurrence of scratches on the members constituting the sliding portion due to the heat conductive material.

[0028] Here, the "sliding portion" means a portion where a sliding member (for example, in a fixing device, a sliding sheet disposed on the inner peripheral surface of a fixing belt, etc.) and a member to be slid (for example, a fixing belt, etc. in a fixing device) face each other and slide relatively. And the lubricating composition according to the present embodiment is applied to sliding parts such as fixing devices, sliding bearings, and rolling bearings.

[0029] Hereinafter, the details of the lubricating composition according to the present embodiment will be described.

[0030] (Lubricating oil) Examples of the lubricating oil (i.e., base oil) include grease, silicone oil (e.g., dimethyl silicone oil, dimethyl silicone oil with an organometallic salt added, dimethyl silicone oil with a hindered amine added, dimethyl silicone oil with an organometallic salt and a hindered amine added, methylphenyl silicone oil, amino-modified silicone oil, amino-modified silicone oil with an organometallic salt added, amino-modified silicone oil with a hindered amine added, carboxy-modified silicone oil, silanol-modified silicone oil, sulfonic acid-modified silicone oil, etc.), and fluorine oil (e.g., fluorosilicone oil, perfluoropolyether oil, etc.).

[0031] Among these, from the viewpoints of heat resistance and lubricity, as the lubricating oil, at least one selected from the group consisting of silicone oil and perfluoropolyether is preferable.

[0032] In particular, as the silicone oil, amino-modified silicone oil is preferable. The amino-modified silicone oil has a high affinity with fibrous carbon, and the dispersibility of specific aggregates in the lubricating oil is improved. As a result, furthermore, the thermal conductivity of the lubricating composition becomes high, and the lubricity also becomes high.

[0033] When the lubricating composition contains perfluoropolyether, it is preferable that the lubricating composition further contains a fluorine-based surfactant. When the lubricating composition contains a fluorine-based surfactant together with perfluoropolyether, the affinity with fibrous carbon becomes high, and the dispersibility of specific aggregates in the lubricating oil is improved. As a result, furthermore, the thermal conductivity of the lubricating composition becomes high, and the lubricity also becomes high.

[0034] Here, examples of the fluorosurfactant include compounds having a fluoroalkyl or fluoroalkylene group in at least part of the main chain, side chain, and terminal. Specific examples of the fluorosurfactant include well-known fluorosurfactants such as perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, perfluoroalkyl ethylene oxides, perfluoroalkyl amine compounds, and perfluoroalkyl betaines. Among these, from the viewpoints of thermal conductivity and lubricity, perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, and perfluoroalkyl amine compounds are preferable as the fluorosurfactant. From the viewpoints of thermal conductivity and lubricity, the content of the fluorosurfactant is preferably 0.5% by mass or more and 5% by mass or less, more preferably 1% by mass or more and 3% by mass or less, and still more preferably 1.5% by mass or more and 2.5% by mass or less with respect to the lubricating oil.

[0035] (Specific aggregate) The specific aggregate is an aggregate (specific aggregate) in which a plurality of fibrous carbons are intertwined with each other. The specific aggregate is used as a thermal conductive material.

[0036] The maximum diameter of the specific aggregate is preferably 5 μm or more and 100 μm or less, more preferably 20 μm or more and 80 μm or less, still more preferably 10 μm or more and 50 μm or less, and particularly preferably 15 μm or more and 40 μm or less.

[0037] By setting the maximum diameter of the specific aggregate to 5 μm or more, the thermal conductivity of the lubricating composition is likely to be improved. On the other hand, by setting the maximum diameter of the specific aggregate to 100 μm or less, an increase in the frictional resistance of the lubricating composition due to the enlargement of the specific aggregate is suppressed, and the lubricity is likely to be improved.

[0038] The specific aggregate may be an aggregate in which a plurality of fibrous carbons are intertwined with each other, and the shape is not particularly limited. The specific aggregate may be, for example, spherical, ellipsoidal, or irregular in shape.

[0039] The ratio of the major axis Y to the minor axis X (aspect ratio, major axis Y / minor axis X) of the specific aggregate is preferably 30 or more and 200 or less, more preferably 40 or more and 150 or less, still more preferably 50 or more and 100 or less, and particularly preferably 50 or more and 80 or less. In particular, by setting the ratio of the major axis Y to the minor axis X (aspect ratio, major axis Y / minor axis X) of the specific aggregate to 1 / 10 or more, the amount of deformation of the specific aggregate due to pressure increases, and the lubricating oil held inside is likely to ooze out. As a result, the wear resistance is likely to decrease.

[0040] ·Measurement of the maximum diameter, minor axis X, and major axis Y of the specific aggregate The maximum diameter, minor axis X, and major axis Y of the specific aggregate are measured by the following method. The lubricating composition to be measured is applied with a thickness of 50 μm. The obtained coating is observed with an electron microscope, and the major axis Y, which is the longest axis of the specific aggregate, and the minor axis X, which is the longest axis in the direction perpendicular to the major axis Y, are measured. The number of measurement samples of the specific aggregate is 10. The maximum value of the major axis Y among the 10 samples is defined as the "maximum diameter of the specific aggregate", and the "minor axis X" and "major axis Y" are the arithmetic mean values of the 10 samples, respectively.

[0041] The fibrous carbon contained in the specific aggregate preferably has a length of 1 μm or more and 100 μm or less, more preferably 2 μm or more and 80 μm or less, and still more preferably 3 μm or more and 60 μm or less.

[0042] The fibrous carbon contained in the specific aggregate preferably has a diameter of 20 nm or more and 300 nm or less, more preferably 25 nm or more and 250 nm or less, and still more preferably 30 nm or more and 200 nm or less.

[0043] The length and diameter of the fibrous carbon constituting the specific aggregate are measured by the following method. The coating of the lubricating composition observed in the above-mentioned "measurement of the maximum diameter, minor axis X, and major axis Y of the specific aggregate" is observed with an electron microscope, and the length and diameter of the fibrous carbon constituting the specific aggregate are measured. The number of measurement samples of the specific aggregate is 10, and the measurement is performed on two fibrous carbons for each specific polymer. The "length of the fibrous carbon constituting the specific aggregate" and the "diameter of the fibrous carbon constituting the specific aggregate" are each the arithmetic mean value of the measurement values for 20 points (10 samples × 2 pieces).

[0044] The number of fibrous carbons contained in the specific aggregate may be plural (that is, two or more), and is not particularly limited.

[0045] The fibrous carbon contained in the specific polymer is preferably a carbon nanotube from the viewpoints of availability and thermal conductivity, etc.

[0046] The content of the specific aggregate is preferably 5% by mass or more and 50% by mass or less, more preferably 7.5% by mass or more and 45% by mass or less, and particularly preferably 10% by mass or more and 40% by mass or less, based on the lubricating oil. By setting the content of the specific aggregate to 5% by mass or more, the thermal conductivity of the lubricating composition due to the inclusion of the specific aggregate is likely to be improved. On the other hand, by setting the content of the specific aggregate to 50% by mass or less, the wear resistance is likely to be reduced by both the lubricating oil and the specific aggregate.

[0047] (Other additives) The lubricating composition according to the present embodiment may contain other additives other than the lubricating oil and the specific aggregate. Examples of the other additives include fluororesin particles such as polytetrafluoroethylene (PTFE) particles; silicone particles; well-known additives such as antioxidants.

[0048] (Method for producing the lubricating composition) The lubricating composition according to the present embodiment is produced, for example, as follows. Note that the method for producing the lubricating composition described below is an example.

[0049] First, a lubricating oil and fibrous carbon are mixed to prepare a fibrous carbon-dispersed lubricating oil.

[0050] The obtained fibrous carbon dispersed lubricating oil is subjected to a high-pressure dispersion treatment, whereby the fibrous carbon in the lubricating oil is loosened and individually isolated, and further the length of the fibrous carbon in the lubricating oil is adjusted. Here, the conditions of the high pressure dispersion treatment may be any conditions that allow the fibrous carbon to be individually isolated and the length of the fibrous carbon to be adjusted to a desired value. For example, the high pressure dispersion treatment is preferably performed under a liquid temperature of the dispersion liquid of 25°C or more and 90°C or less, and a pressure of 1 MPa or more and 100 MPa or less (preferably, 3 MPa or more and 80 MPa or less). The high pressure dispersion treatment is carried out using a high pressure homogenizer or the like.

[0051] The length of the fibrous carbon in the lubricating oil is preferably adjusted to about 1 μm or more and 100 μm or less (preferably, 3 μm or more and 50 μm or less). Here, the length of the fibrous carbon in the lubricating oil can be measured by observation with an optical microscope or an electron microscope. The maximum diameter of a particular aggregate can be controlled by the length of the fibrous carbon in the lubricating oil. Specifically, the longer the fibrous carbon, the larger the tendency to produce aggregates with a larger maximum diameter.

[0052] Next, the fibrous carbon dispersed lubricating oil is stirred in a planetary mixer to produce a specific aggregate in the system. By stirring the fibrous carbon dispersed lubricating oil with a planetary mixer, the fibrous carbon that was individually isolated in the fibrous carbon dispersed lubricating oil gradually becomes entangled and forms lumps, producing a specific aggregate.

[0053] Here, the stirring conditions using the planetary mixer may be any conditions under which specific aggregates having the desired maximum diameter can be obtained. For example, the stirring conditions are preferably such that the liquid temperature of the fibrous carbon dispersed lubricant oil is 25° C. or higher and 60° C. or lower, and the stirring is carried out for 3 to 90 minutes. The maximum diameter of the specific aggregate can be controlled by the stirring conditions. Specifically, the longer the stirring time by a planetary mixer, the more likely it is to produce an aggregate with a larger maximum diameter.

[0054] All of the fibrous carbon contained in the fibrous carbon-dispersed lubricating oil may form into specific aggregates, and together with the specific aggregates, some fibrous carbon that has not formed into specific aggregates (i.e., fibrous carbon that is not intertwined with each other) may remain.

[0055] As described above, a lubricating composition containing a lubricating oil and specific aggregates is obtained. Note that the ratio of the minor axis Y to the major axis X (minor axis Y / major axis X) of the specific aggregate can be controlled by the rotational speed of the planetary mixer. Specifically, the higher the rotational speed of the planetary mixer, the more likely it is to produce a smaller aggregate.

[0056] (Properties of the lubricating composition) The thermal conductivity of the lubricating composition according to this embodiment is preferably 0.1 W / m·K or more and 30 W / m·K or less, more preferably 1 W / m·K or more and 20 W / m·K or less, and even more preferably 2 W / m·K or more and 15 W / m·K or less.

[0057] The thermal conductivity of the lubricating composition is measured as follows. That is, the thermal conductivity is determined from the thermal diffusivity in the thickness direction of a sample of the lubricating composition. Specifically, after placing the test piece on the probe of a thermal conductivity measuring device, EyePhase Mobile (manufactured by EyePhase Co., Ltd.), a 50 gf weight is placed, and the thermal conductivity is measured three times under the conditions of 1.41 V, 3 Hz to 100 Hz divided into 10 steps, and a measurement time of 2 seconds in manual mode. The arithmetic mean value of the three measurement values is taken as the thermal conductivity of the lubricating composition.

[0058] (Image forming apparatus / Fixing apparatus) The image forming apparatus according to this embodiment An image carrier, A latent image forming device that forms a latent image on the surface of the image carrier, A developing device that develops the latent image into a toner image using a developer, A transfer device that transfers the toner image developed on the recording medium, A fixing device that fixes the toner image on the recording medium, and is provided with the following.

[0059] The fixing device provided in the image forming apparatus according to the present embodiment has a first rotating body, a second rotating body disposed in contact with the first rotating body, a pressing member disposed on the inner surface of the second rotating body and pressing the second rotating body against the first rotating body from the inner surface of the second rotating body, a sliding member interposed between the inner surface of the second rotating body and the pressing member, a lubricating composition interposed between the inner surface of the second rotating body and the sliding member, and is provided with the following.

[0060] And, the lubricating composition provided in the fixing device according to the present embodiment is the lubricating composition according to the above present embodiment.

[0061] Hereinafter, an example of the image forming apparatus and the fixing device according to the present embodiment will be described with reference to the drawings.

[0062] FIG. 1 is a schematic diagram showing an example of the image forming apparatus according to the present embodiment. FIG. 2 is a schematic diagram showing an example of the fixing device according to the present embodiment.

[0063] As shown in FIG. 1, the image forming apparatus 100 according to the present embodiment includes electrophotographic first to fourth process cartridges 10Y, 10M, 10C, 10K (an example of an image forming unit) that output images of respective colors of yellow (Y), magenta (M), cyan (C), and black (K) based on color-separated image data. These process cartridges 10Y, 10M, 10C, 10K are arranged side by side at intervals along the outer peripheral surface of the intermediate transfer belt 20. Note that these process cartridges 10Y, 10M, 10C, 10K are detachable from the image forming apparatus main body.

[0064] Above each of the process cartridges 10Y, 10M, 10C, and 10K (in FIG. 1), an intermediate transfer belt 20 as an intermediate transfer member is provided such that its outer peripheral surface faces each of the process cartridges. The intermediate transfer belt 20 is wound around a drive roller 22 and a support roller 24 that is in contact with the inner surface of the intermediate transfer belt 20 and is arranged so as to be separated from each other, and is disposed while being tensioned, and is endlessly run in the direction from the first process cartridge 10Y to the fourth process cartridge 10K.

[0065] The support roller 24 is pressed in a direction away from the drive roller 22 by an elastic member such as a spring (not shown), and tension is applied to the intermediate transfer belt 20 wound between the two. Further, an intermediate transfer member cleaning device 20a is provided on the outer peripheral surface of the intermediate transfer belt 20 so as to face the drive roller 22.

[0066] Since the first to fourth process cartridges 10Y, 10M, 10C, and 10K have substantially the same configuration, here, the first process cartridge 10Y that forms a yellow image disposed on the upstream side in the running direction of the intermediate transfer belt will be described as a representative. In addition, the same reference numerals with magenta (M), cyan (C), and black (K) instead of yellow (Y) are given to the same parts as those of the first process cartridge 10Y, and the description of the second to fourth process cartridges 10M, 10C, and 10K is omitted.

[0067] The first process cartridge 10Y has a photoreceptor 1Y that acts as an image holding member. Around the photoreceptor 1Y, a charging roller (an example of a charging device) 2Y that charges the surface of the photoreceptor 1Y to a predetermined potential, a developing device 4Y that supplies charged toner contained in the developer to the electrostatic latent image to develop the electrostatic latent image, and a photoreceptor cleaning device 6Y that removes the toner remaining on the surface of the photoreceptor 1Y after primary transfer are sequentially arranged. These are integrally configured within a housing 11Y (a casing). Similarly, in the first process cartridges 10M to 10Y, each member is integrally configured within housings 11M to 11Y (casings).

[0068] Then, together with the first process cartridge 10Y, a primary transfer roller 5Y (an example of a primary transfer device) that transfers the developed toner image onto the intermediate transfer belt 20, and an exposure device 3 that exposes the charged surface with a laser beam 3Y based on the color-separated image signal to form an electrostatic latent image are arranged to constitute an image forming unit. Note that the charging roller 2Y and the exposure device 3 correspond to an example of a latent image forming device.

[0069] Note that the primary transfer roller 5Y is arranged inside the intermediate transfer belt 20 and provided at a position facing the photoreceptor 1Y. Further, bias power supplies (not shown) for applying a primary transfer bias are connected to the respective primary transfer rollers 5Y, 5M, 5C, and 5K. Each bias power supply varies the transfer bias applied to each primary transfer roller under the control of a control unit (not shown).

[0070] As shown in FIG. 2, the fixing device 28 includes a heating roll 30 (an example of a first rotating body) and a pressure belt 40 (an example of a second rotating body), and the heating roll 30 and the pressure belt 40 are provided to face each other. The pressure belt 40 is pressed against the heating roll 30 by a pressing pad 50 (an example of a pressing member) disposed inside its circumference to form a contact portion while being guided along a belt travel guide 52 and driven by receiving a driving force from the heating roll 30. In the figure, T indicates a toner image.

[0071] The heating roll 30 is configured, for example, by sequentially forming an elastic body layer 30b and a release layer 30c on a metal hollow core metal core 30a having a heating source 31 such as a halogen lamp inside.

[0072] The metal core 30a is composed of, for example, a cylindrical body made of metal such as aluminum or stainless steel. The elastic layer 30b is composed of, for example, HTV silicone rubber, fluororubber, etc. (rubber hardness of about 45 degrees on the JIS-A scale, and the rubber hardness was measured by a spring-type A durometer manufactured by Teclock Co., Ltd. in accordance with JIS K6301 with a load of 1,000 gf added) with a thickness of about 2 mm or more and 5 mm or less. The release layer 30c is composed of, for example, fluororubber, silicone rubber, fluororesin, etc. with a thickness of 20 μm or more and 50 μm or less. Of course, it is not limited to these, and it may be composed of conventionally known materials.

[0073] The heating roll 30, and the fixing roll (not shown) is rotationally driven at a peripheral speed of, for example, 260 mm / sec with its speed adjusted by a drive source (not shown). The outer diameter of the heating roll 30 is generally about 25 mm or more and 80 mm or less, for example.

[0074] The surface temperature of the heating roll 30 is detected by a temperature sensor (not shown) in contact with the surface, and is controlled by a control circuit (not shown) so that the surface temperature becomes, for example, 175°C.

[0075] The pressure belt 40 is configured by forming a release layer on a resin base material containing a heat-resistant resin such as polyimide resin, for example. The resin base material and the release layer are composed of conventionally known materials.

[0076] The pressing pad 50 has two pressing portions 51a and 51b with different hardnesses along the advancing direction of the recording medium P. The pressing portion 51a on the side where the recording medium P enters in the pressing pad 50 is formed of a rubber-like elastic member, and the pressing portion 51b on the side where the recording medium P is discharged is formed of a hard pressure-applying member such as metal, so that the pressure in the contact area is made higher on the side where the recording medium P is discharged than on the side where the recording medium P enters. The pressing portions 51a and 51b are supported by a holder 51c, and press the heating roll 30 from the inner peripheral surface of the pressure belt 40 via a sliding sheet 60 (an example of a sliding member).

[0077] Between the sliding sheet 60 and the inner peripheral surface of the pressure belt 40, a lubricating composition 62 is interposed. The lubricating composition 62 is supplied to the inner peripheral surface of the pressure belt 40 by a lubricating composition supply member 64 provided, for example, on a part of the belt running guide 52, and is interposed between the sliding sheet 60 and the inner peripheral surface of the pressure belt 40.

[0078] The sliding sheet 60 (an example of a sliding member) is preferably a sheet made of a heat-resistant resin. Further, well-known other additives may be added to the sliding sheet 60.

[0079] Examples of the heat-resistant resin include fluororesin, polyimide resin, polyamide resin, polyamideimide resin, polyetherimide resin, polyethersulfone resin, polyetherketone resin, bismaleimide triazine resin, aramid resin, polyphenylene resin, polyphenylene sulfide resin, etc. Among them, fluororesin is preferable from the viewpoints of heat resistance and slidability.

[0080] The fluororesin preferably includes a fluororesin subjected to electron beam crosslinking. Specifically, for example, polytetrafluoroethylene (PTFE) subjected to electron beam crosslinking is preferably mentioned. Note that a fluororesin subjected to electron beam crosslinking (for example, electron beam crosslinked PTFE) may be blended with an uncrosslinked fluororesin (for example, uncrosslinked PTFE) and used.

[0081] The heat-resistant resin is a resin that does not melt or decompose even when the temperature of the apparatus rises (for example, the fixing temperature).

[0082] The sliding sheet 60 may be porous (having a large number of pores). Thereby, the holding ability of the lubricating composition 62 is improved. The porous sliding sheet 60 includes, for example, a heat-resistant resin foamed and made porous, a heat-resistant resin stretched in a uniaxial or biaxial direction and made porous, or sintering molding.

[0083] In addition, when adopting the porous sliding sheet 60, it is preferable to interpose a lubricant composition permeation prevention member (sheet member) that prevents the permeation of the lubricant composition 62 on the pressing pad 50 side between the sliding sheet 60 and the pressing pad 50.

[0084] The supply amount of the lubricant composition 62 may be an amount that can cover the surface of the sliding sheet. The surplus moves to a location where there are no functional problems (such as the supply felt or the guide surface) as it is used.

[0085] Hereinafter, the image forming operation of the image forming apparatus according to the present embodiment will be described. Note that the image forming operation will be described by taking the operation of forming a yellow image in the first process cartridge 10Y as an example.

[0086] First, prior to the image forming operation, the surface of the photoreceptor 1Y is charged to a potential of, for example, about -600 V or more and -800 V or less by the charging roller 2Y.

[0087] The photoreceptor 1Y is formed, for example, by laminating a photosensitive layer on a conductive substrate. This photosensitive layer is usually, for example, highly resistive, but has the property that when irradiated with the laser beam 3Y, the specific resistance of the portion irradiated with the laser beam changes. Therefore, according to the yellow image data sent from a control unit (not shown), the laser beam 3Y is output via the exposure device 3 onto the surface of the charged photoreceptor 1Y. The laser beam 3Y is irradiated onto the photosensitive layer on the surface of the photoreceptor 1Y, thereby forming an electrostatic latent image of the yellow printing pattern on the surface of the photoreceptor 1Y.

[0088] The electrostatic latent image thus formed on the photoreceptor 1Y is rotated to the developing position as the photoreceptor 1Y travels. Then, at this developing position, the electrostatic latent image on the photoreceptor 1Y is visualized (toner image) by the developing device 4Y.

[0089] In the developing device 4Y, for example, a developer containing yellow toner and carrier is accommodated. The yellow toner is triboelectrically charged by being agitated inside the developing device 4Y and has a charge of the same polarity (negative polarity) as the charged charge on the photoreceptor 1Y. As the surface of the photoreceptor 1Y passes through the developing device 4Y, the yellow toner electrostatically adheres only to the discharged latent image portion on the surface of the photoreceptor 1Y, and the latent image is developed by the yellow toner. The photoreceptor 1Y on which the yellow toner image is formed continues to run, and the toner image developed on the photoreceptor 1Y is conveyed to the primary transfer position.

[0090] When the yellow toner image on the photoreceptor 1Y is conveyed to the primary transfer, a primary transfer bias is applied to the primary transfer roller 5Y, and an electrostatic force from the photoreceptor 1Y toward the primary transfer roller 5Y acts on the toner image, and the toner image on the photoreceptor 1Y is transferred onto the intermediate transfer belt 20. The transfer bias applied at this time has a polarity (+) opposite to the polarity (-) of the toner, and for example, in the first process cartridge 10Y, it is controlled to a constant current of about +10 μA by a control unit (not shown).

[0091] Also, the primary transfer biases applied to the primary transfer rollers 5M, 5C, and 5K after the second process cartridge 10M are similarly controlled.

[0092] In this way, the intermediate transfer belt 20 onto which the yellow toner image is transferred by the first process cartridge 10Y is sequentially conveyed through the second to fourth process cartridges 10M, 10C, and 10K, and the toner images of each color are similarly overlapped and multi-transferred.

[0093] The intermediate transfer belt 20 on which toner images of all colors are multiply transferred through the first to fourth process cartridges reaches a secondary transfer unit composed of the intermediate transfer belt 20, a support roller 24 in contact with the inner surface of the intermediate transfer belt 20, and a secondary transfer roller (an example of a secondary transfer device) 26 disposed on the image holding surface side of the intermediate transfer belt 20. On the other hand, the recording medium P is fed between the secondary transfer roller 26 and the intermediate transfer belt 20 via a supply mechanism, and a secondary transfer bias is applied to the support roller 24. The transfer bias applied at this time has a (-) polarity, the same polarity as the polarity of the toner (-). An electrostatic force directed from the intermediate transfer belt 20 toward the recording medium P acts on the toner image, and the toner image on the intermediate transfer belt 20 is transferred onto the recording medium P. Note that the secondary transfer bias at this time is determined according to the resistance detected by a resistance detection means (not shown) that detects the resistance of the secondary transfer unit, and is controlled at a constant voltage. Note that the intermediate transfer belt 20, the primary transfer roller 5Y, and the secondary transfer roller 26 correspond to an example of a transfer device.

[0094] Thereafter, the recording medium P is fed into the fixing device 28 and inserted into a contact area formed by the pressure contact of a heating roller 30 that is rotationally driven in the direction of the arrow and a pressure belt 40. At this time, the recording medium P is inserted so that the surface of the recording medium P on which the unfixed toner image is formed faces the surface of the heating roller 30. When the recording medium P passes through this contact area, heat and pressure are applied to the recording medium P, and the unfixed toner image is fixed to the recording medium P. After passing through the contact area, the fixed recording medium is peeled off from the heating roller 30 and discharged from the fixing device 28.

[0095] In this way, the fixing process is performed and permanently fixed on the recording medium P. The recording medium P on which the fixing of the color image is completed is carried out toward the discharge unit, and a series of color image forming operations is terminated.

Example

[0096] Examples will be described below, but the present invention is not limited to these examples. In the following description, unless otherwise specified, all "parts" and "%" are based on mass.

[0097] <Example 1> The lubricating oil shown in Table 1 and carbon nanotubes (manufactured by Showa Denko K.K.) were mixed to obtain a CNT-dispersed lubricating oil. The amount of carbon nanotubes to be mixed was such that the content of the obtained specific aggregate became the value shown in Table 1. Next, the CNT-dispersed lubricating oil was subjected to high-pressure dispersion treatment (conditions: 5 times at 50 MPa) using a high-pressure homogenizer (manufactured by Maruwan Machinery Co., Ltd., HC3). Subsequently, 530 parts by mass of a polyamic acid solution (manufactured by Unitika Ltd.: TX-HMM (polyimide varnish), solid content concentration: 18% by mass, solvent: NMP) was added to 100 parts by mass of the dispersion liquid after the high-pressure dispersion treatment to prepare a precursor liquid. The obtained precursor liquid (liquid temperature 30°C) was stirred for 15 minutes at a revolution speed of 30 rpm and a rotation speed of 60 rpm while evacuating using a planetary mixer (manufactured by Aikosha Co., Ltd., ACM-5LVT). As described above, a lubricating composition containing an aggregate in which a plurality of carbon nanotubes are intertwined with each other (i.e., a specific aggregate) and a lubricating oil was obtained.

[0098] <Examples 2 to 5> A lubricating composition was obtained in the same manner as in Example 1, except that the rotation speed of the planetary mixer and the stirring time by the planetary mixer were changed to the following conditions. · Example 2: Rotation speed (revolution 15 rpm, rotation 35 rpm), stirring time 15 minutes · Example 3: Rotation speed (revolution 20 rpm, rotation 40 rpm), stirring time 15 minutes · Example 4: Rotation speed (revolution 40 rpm, rotation 70 rpm), stirring time 15 minutes · Example 5: Rotation speed (revolution 50 rpm, rotation 100 rpm), stirring time 15 minutes

[0099] <Examples 6 to 9> As shown in Table 1, a lubricating composition was obtained in the same manner as in Example 1, except that the content of the heat conductive material (CNT aggregate) was changed.

[0100] <Example 10> A lubricating composition was obtained in the same manner as in Example 1, except that the lubricating oil was changed to "dimethyl silicone oil".

[0101] <Example 11> A lubricating composition was obtained in the same manner as in Example 1, except that the lubricating oil was changed to "perfluoropolyether oil" and a fluorine-based surfactant was added.

[0102] <Example 12> A lubricating composition was obtained in the same manner as in Example 11, except that the fluorine-based surfactant was not added.

[0103] <Comparative Examples 1-2> The lubricating oil and the heat conductive material shown in Table 1 were mixed in the blending amounts shown in Table 1 to obtain a lubricating composition.

[0104] <Properties> The following properties of the lubricating composition of each example were measured according to the methods described above. ·Thermal conductivity ·The maximum diameter, minor axis X, and major axis Y of an aggregate formed by a plurality of carbon nanotubes intertwined with each other

[0105] <Evaluation> The lubricating composition of each example was applied to the sliding surface of the sliding sheet to obtain a sliding sheet with the lubricating composition. The obtained sliding sheet with the lubricating composition was attached to the sliding part in the fixing device of the image forming apparatus "Color1000 Press" manufactured by Fuji Film Business Innovation Co., Ltd. The obtained apparatus was used as an evaluation machine, and the following evaluation was carried out.

[0106] (Measurement of the drive motor torque of the fixing device) After continuously outputting 300,000 solid images on A4 paper, the drive motor torque of the fixing device was measured as follows. The driving motor torque was calculated and derived from the current value of the DC motor that drives the fixing device. The characteristics of the rotational speed and driving force (torque) of the driving motor with respect to a known driving load were measured in advance, and the driving motor torque (Nm) was calculated from the driving motor drive current of the actual object.

[0107] (Paper wrinkle) Solid images were continuously output on A4 paper. Then, evaluation was performed based on the following evaluation criteria according to the cumulative number of sheets of the output paper when paper wrinkles occurred. A: The cumulative number of sheets of paper is 300,000 and no paper wrinkles occurred. B: When paper wrinkles occurred, the cumulative number of sheets of paper was 200,000 or more and less than 300,000. C: When paper wrinkles occurred, the cumulative number of sheets of paper was 100,000 or more and less than 200,000. D: When paper wrinkles occurred, the cumulative number of sheets of paper was 50,000 or more and less than 100,000. E: When paper wrinkles occurred, the cumulative number of sheets of paper was less than 50,000.

[0108] (Image density unevenness) Solid images were continuously output on A4 paper. Then, evaluation was performed based on the following evaluation criteria according to the cumulative number of sheets of the output paper when density unevenness occurred in the solid image. A: The cumulative number of sheets of paper is 300,000 and no image density unevenness occurred. B: When image density unevenness occurred, the cumulative number of sheets of paper was 200,000 or more and less than 300,000. C: When image density unevenness occurred, the cumulative number of sheets of paper was 100,000 or more and less than 200,000. D: When image density unevenness occurred, the cumulative number of sheets of paper was 50,000 or more and less than 100,000. E: When image density unevenness occurred, the cumulative number of sheets of paper was less than 50,000.

[0109] In addition, the details of the materials or abbreviations used in the examples shown in Table 1 are as follows. · Amino-modified silicone oil: "KF8009" manufactured by Shin-Etsu Chemical Co., Ltd. · Dimethyl silicone oil: "KF96" manufactured by Shin-Etsu Chemical Co., Ltd. · Perfluoropolyether oil: "Demnum" manufactured by Daikin Industries, Ltd. · Fluorine-based surfactant: "Fluorine monosided terminal modified affinity agent SA" manufactured by Daikin Industries, Ltd.

[0110] · CNT aggregate: An aggregate formed by a plurality of carbon nanotubes (manufactured by Showa Denko K.K., diameter 0.4 nm, length 6 μm) intertwined with each other · Single CNT: (manufactured by Showa Denko K.K., diameter 0.4 nm, length 6 μm) · Potassium titanate: "Dentol" manufactured by Otsuka Chemical Co., Ltd., maximum diameter = 10 μm

[0111]

Table 1

[0112] From the above results, it can be seen that the lubricating composition of the example has a lower driving motor torque of the fixing device and suppresses the occurrence of paper wrinkles and image density unevenness compared to the lubricating composition of the comparative example. Thereby, it can be seen that the lubricating composition of the example has a higher thermal conductivity and higher lubricity compared to the lubricating composition of the comparative example.

Explanation of symbols

[0113] 1Y, 1M, 1C, 1K photoreceptor 2Y, 2M, 2C, 2K charging roller 3Y, 3M, 3C, 3K laser beam 3 exposure device 4Y, 4M, 4C, 4K developing device 5Y, 5M, 5C, 5K primary transfer roller 6Y, 6M, 6C, 6K photoreceptor cleaning device 10Y, 10M, 10C, 10K process cartridge 20 intermediate transfer belt 20a intermediate transfer body cleaning device 22 drive roller 24 support roller 26 secondary transfer roller 28 fixing device 30 Heating Roll 40 Pressing Belt 50 Pressing Pad 52 Belt Travel Guide 60 Sliding Sheet 62 Lubricating Composition 64 Lubricating Composition Supply Member 100 Image Forming Apparatus P Recording Medium

Claims

1. A lubricating composition comprising a lubricating oil and an aggregate formed by intertwining a plurality of fibrous carbons with each other, wherein the maximum diameter of the aggregate is 5 μm or more and 100 μm or less.

2. A lubricating composition comprising a lubricating oil and an aggregate formed by intertwining a plurality of fibrous carbons with each other, wherein the ratio of the major axis Y to the minor axis X of the aggregate (aspect ratio = major axis Y / minor axis X) is 30 or more and 200 or less.

3. A lubricating composition comprising a lubricating oil, an aggregate formed by intertwining a plurality of fibrous carbons with each other, and amino-modified silicone oil as a lubricant.

4. The lubricating composition according to any one of Claims 1 to 3, wherein the fibrous carbon is a carbon nanotube.

5. The lubricating composition according to Claim 2 or Claim 3, wherein the maximum diameter of the aggregate is 5 μm or more and 100 μm or less.

6. The lubricating composition according to Claim 5, wherein the maximum diameter of the aggregate is 20 μm or more and 80 μm or less.

7. The lubricating composition according to Claim 1 or Claim 3, wherein the ratio of the major axis Y to the minor axis X of the aggregate (aspect ratio = major axis Y / minor axis X) is 30 or more and 200 or less.

8. The lubricating composition according to any one of Claims 1 to 7, wherein the content of the aggregate is 5% by mass or more and 50% by mass or less with respect to the lubricating oil.

9. The lubricating composition according to Claim 8, wherein the content of the aggregate is 10% by mass or more and 40% by mass or less with respect to the lubricating oil.

10. The lubricating composition according to Claim 1 or Claim 2, wherein the lubricating oil contains at least one selected from the group consisting of silicone oil and perfluoropolyether.

11. The lubricating composition according to Claim 10, wherein the silicone oil is amino-modified silicone oil.

12. The lubricating composition according to Claim 10 or Claim 11, wherein when the lubricating oil contains perfluoropolyether, it further contains a fluorine-based surfactant.

13. A first rotating body, A second rotating body disposed in contact with the first rotating body, A pressing member disposed on the inner surface of the second rotating body and pressing the second rotating body against the first rotating body from the inner surface of the second rotating body, A sliding member interposed between the inner surface of the second rotating body and the pressing member, The lubricating composition according to any one of Claims 1 to 12 interposed between the inner surface of the second rotating body and the sliding member, and a fixing device comprising the same.

14. An image carrier, A latent image forming device that forms a latent image on the surface of an image holding body, A developing device that develops the latent image into a toner image using a developer, A transfer device that transfers the toner image developed on a recording medium, The fixing device according to claim 13 that fixes the toner image on the recording medium, An image forming apparatus comprising the same.

Images