Fixing device and image forming apparatus

Abstract

To suppress base oil of a lubricant from flowing out to the outside of a region to be lubricated and maintain the performance of a fixing device over a long period.SOLUTION: Provided is a fixing device comprising a rotatable endless film, a heater which is slid on the inner surface of the film via a lubricant, a heater holder for holding the heater, and a pressure member which is contacted under pressure with the heater via the film so as to form a nip part between the heater and itself. The lubricant contains base oil and thickener, and the heater holder has a fitting groove to which the heater is fitted, with an oil repellent part that shows oil repellency to the base oil being provided in a longitudinal range of the nip part in which the heater is slid on the inner surface of the film.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a fixing device used in an electrophotographic image forming apparatus, and to an image forming apparatus equipped with the fixing device. [Background technology]

[0002] A known fixing device used in electrophotography is a film-heating fixing device. The fixing device includes a heater having a resistance heating element on a substrate such as ceramic, a fixing film that rotates while in contact with the heater, and a pressure roller that forms a nip between the heater and the fixing film via the fixing film. A recording material bearing an unfixed toner image is heated while being sandwiched and conveyed between the fixing film and the pressure roller at the nip, thereby fixing the toner image on the recording material.

[0003] In a fixing device that has a film-shaped (endless, belt-shaped) rotating member and a sliding member such as a heater that is in sliding contact with the inner circumferential surface of the rotating member, such as a film heating type fixing device, the sliding friction resistance between the two can be reduced by interposing a lubricant between the inner surface of the rotating member and the sliding member. Patent Document 1 describes a technology that prevents the lubricant from overflowing from the longitudinal end of the fixing film in a film heating type fixing device by providing a groove-shaped recess for storing the lubricant on the downstream side of the heater in the recording material conveyance direction of the support member that supports the heater. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-76589 Summary of the Invention [Problem to be solved by the invention]

[0005] When a grease containing a base oil and a thickener is used as a lubricant in a fixing device, the base oil spreads over the surface of the object to be lubricated to form a sliding film. Because the base oil has a relatively high fluidity, it may leak outside the area to be lubricated (for example, the inner surface of the fixing film and the sliding surface of the heater that slides against this inner surface). If the base oil leaks outside the area to be lubricated, various problems may occur, such as increased sliding friction resistance due to lubricant depletion, contamination of the recording material or transport problems due to base oil seeping into the nip area, and swelling of the release layer of the pressure roller.

[0006] In addition, when the lubricant temperature rises, the base oil tends to separate from the thickener. Compared to the viscous lubricant, the base oil separated from the thickener is a low-viscosity liquid, and is therefore more likely to flow out due to capillary action through gaps between components. In the configuration described in the above document, although the groove-like recesses can restrict the flow direction of the lubricant, it is difficult to prevent the base oil from flowing out due to capillary action.

[0007] Therefore, the present invention aims to provide a fixing device that can prevent the base oil of the lubricant from leaking outside the lubrication target area and maintain performance over a long period of time, and an image forming device equipped with this fixing device. [Means for solving the problem]

[0008] One aspect of the present invention is a fixing device comprising a rotatable endless film, a heater that slides on the inner surface of the film via a lubricant, a heater holder that holds the heater, and a pressure member that is pressed against the heater via the film and forms a nip portion between the heater and the heater, wherein a recording material on which a toner image has been formed is sandwiched and transported between the film and the pressure member at the nip portion, and the toner image is fixed to the recording material using the film heated by the heater, wherein the lubricant includes a base oil and a thickener, the heater holder has a fitting groove in which the heater is fitted, and the fitting groove is provided with an oil-repellent portion that is oil-repellent to the base oil within the range in which the heater slides on the inner surface of the film in the longitudinal direction of the nip portion. [Effects of the Invention]

[0009] According to the present invention, the base oil of the lubricant is prevented from leaking out of the area to be lubricated, and performance can be maintained for a long period of time. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram of an image forming apparatus according to a first embodiment. [Figure 2] 1A is a cross-sectional view of a fixing device according to a first embodiment, and FIG. 1B is a longitudinal-sectional view of the fixing device according to the first embodiment. [Figure 3] FIG. 3 is a diagram showing the range where oil repellent treatment is performed in the first embodiment. [Figure 4] 5A is a schematic diagram showing the state of intrusion of lubricant and base oil into the gap between the heater and the heater holder in the conventional example (a), the comparative example (b), and the first embodiment (c). FIG. [Figure 5] FIG. 10(a) is a diagram showing the range where oil repellent treatment is performed in the second embodiment, and FIG. 10(b) is a schematic diagram for explaining the effect of the oil repellent treatment. [Figure 6] 10A and 10B are schematic diagrams showing an example of the configuration of a fixing device according to a fourth embodiment. [Figure 7] 10A to 10C are diagrams for explaining the range to which oil repellent treatment is applied in the fifth embodiment. [Figure 8] FIG. 10A shows the fitted state of the heater and heater holder, and a schematic diagram showing how the lubricant and base oil penetrate into the gap between the heater and heater holder in a conventional example (b), a comparative example (c), and a fifth embodiment (d). [Figure 9] 13A and 13B are diagrams showing the range where oil repellent treatment is performed in the sixth embodiment. [Figure 10] 13A and 13B are diagrams showing the range where oil repellent treatment is performed in the seventh embodiment. [Figure 11] FIG. 13 is a diagram showing the range where oil repellent treatment is performed in the eighth embodiment. [Figure 12] FIG. 13 is a diagram showing the range where oil repellent treatment is performed in the ninth embodiment. [Figure 13] FIG. 22 is a diagram showing the range where oil repellent treatment is performed in the tenth embodiment. [Figure 14] FIG. 23 is a diagram showing the range where oil repellent treatment is performed in the eleventh embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0012] First Embodiment A first embodiment of the present disclosure will be described below. First, the main body configuration of an image forming apparatus according to this embodiment will be described, and then the oil repellent and fixing device according to this embodiment will be described in detail.

[0013] (Image forming device) An example of an image forming apparatus used in this embodiment will be described with reference to the schematic diagram shown in FIG. 1. The image forming apparatus 50 in this embodiment is an electrophotographic monochrome laser beam printer that directly transfers a toner image on a photosensitive drum 1 onto a recording material P. The photosensitive drum 1, which serves as an image carrier, is an electrophotographic photosensitive member formed in a drum (cylindrical) shape. On the circumferential surface of the photosensitive drum 1, a charger 2, an exposure device 3, a developing device 5, a transfer roller 10, and a drum cleaner 16 are arranged in this order along the rotation direction (direction of arrow R1). The image forming unit (process unit) consisting of the photosensitive drum 1, the charger 2, the exposure device 3, the developing device 5, the transfer roller 10, and the drum cleaner 16 constitutes a toner image forming means in this embodiment that forms a toner image on a recording material.

[0014] When image information and an instruction to form an image are input to the image forming apparatus 50, the photosensitive drum 1 is rotated in the direction of arrow R1, and the surface of the photosensitive drum 1 is charged to a predetermined polarity (negative polarity in this example) by the charger 2. Next, the exposure device 3 irradiates the charged surface of the photosensitive drum 1 with laser light L modulated based on the image information, forming an electrostatic latent image on the surface of the photosensitive drum 1. Black toner, which is the developer in this embodiment, is charged to negative polarity, which is the normal charging polarity, inside the developing device 5, and after being carried by the developing roller of the developing device 5, adheres to the photosensitive drum 1 in accordance with the distribution of the surface potential of the photosensitive drum 1. As a result, the electrostatic latent image on the photosensitive drum 1 is developed and visualized as a toner image.

[0015] In parallel with the above process, the recording material P is fed one sheet at a time by a feed roller 4 and conveyed toward the transfer nip Ntr by a conveying roller 6. The transfer nip Ntr, which serves as a transfer section where the toner image is transferred, is a nip formed between the photosensitive drum 1 and a transfer roller 10. A voltage of positive polarity, which is opposite to the normal charging polarity of the toner, is applied to the transfer roller 10 from a power source (not shown), and the toner image on the photosensitive drum 1 is transferred to the recording material P at the transfer nip Ntr. After passing through the transfer nip Ntr, the surface of the photosensitive drum 1 is cleaned by a drum cleaner 16 having a cleaning member such as an elastic blade that contacts the surface of the photosensitive drum 1, and any adhering matter such as residual toner is removed.

[0016] The recording material P, which has passed through the transfer nip Ntr and is carrying an unfixed toner image, is transported to the fixing device 100, undergoes thermal fixing processing by the fixing device 100, and is then discharged as a finished product outside the image forming device 50 by a pair of discharge rollers.

[0017] While a direct transfer type image forming unit in which a toner image is directly transferred from an image carrier to a recording material has been exemplified here, an intermediate transfer type may also be used in which a toner image that has been primarily transferred from an image carrier to an intermediate transfer material such as an intermediate transfer belt is then secondarily transferred from the intermediate transfer material to a recording material. Furthermore, an image forming unit that has multiple image carriers and forms a full-color toner image by superimposing toner images formed using multiple color toners on a recording material may also be used as the toner image forming means. The term "image forming apparatus" is not limited to a printer that forms an image on a recording material based on image information input from an external device, but may also be a copier that forms an image on a recording material based on image information read from a document, or a multifunction machine with multiple functions.

[0018] (fixing device) The fixing device 100 of this embodiment will be described below. The fixing device 100 of this embodiment is a film heating type fixing device that is excellent in shortening the warm-up time and reducing power consumption. Fig. 2(a) is a cross-sectional view showing the fixing device 100 cut along a plane perpendicular to the longitudinal direction B, and Fig. 2(b) is a longitudinal-sectional view showing the fixing device 100 cut along a plane parallel to the longitudinal direction B.

[0019] In the following description, the shapes, arrangements, dimensions, etc. of members related to the fixing device 100 are represented using a recording material conveyance direction A, a longitudinal direction B, and a vertical direction C. The recording material conveyance direction A is the direction in which the recording material P is conveyed at the nip portion (fixing nip N described below) of the fixing device 100. The longitudinal direction B is the lengthwise direction of the fixing nip N and is the width direction of the recording material P passing through the fixing nip N (a direction perpendicular to the recording material conveyance direction A). The vertical direction C is the direction perpendicular to the surface of the recording material P at the fixing nip N. The vertical direction C is also the direction in which the pressure roller 110 presses against the heater 113 at the fixing nip N.

[0020] The fixing device 100 includes a fixing film 112, a heater 113, a heater holder 130, a pressure stay 119, and a pressure roller 110. The heater 113 is held by the heater holder 130. The heater 113 and the heater holder 130 constitute a nip forming unit that forms a fixing nip N together with the pressure roller 110 as a pressure member. The fixing film 112, which is a cylindrical film-like member (belt-like member), is arranged around the nip forming unit. The heater 113 heats the fixing film 112 from the inside while sliding on the inner surface of the rotating fixing film 112. The range in which the heater 113 slides on the fixing film 112 in the longitudinal direction B is defined as the film contact area. The heater holder 130 extends upstream and downstream of the heater 113 in the recording material transport direction A and has a guide function for guiding the rotation (travel) of the fixing film 112.

[0021] The pressure roller 110 contacts the outer surface of the fixing film 112 and is pressed against the heater 113 and heater holder 130 with the fixing film 112 sandwiched between them. The pressure roller 110 is an example of a pressure member, and for example, a belt unit including multiple rollers, including a roller facing the fixing nip, and a belt member stretched across these multiple rollers may be used as the pressure member. The area where the pressure roller 110 and the fixing film 112 contact each other is referred to as the fixing nip N. The pressure roller 110 has a core 117 (FIG. 2(b)), and both ends of the core 117 are rotatably held by a fixing frame 124 via bearings 123. The pressure roller 110 is connected to a drive source (rotating means) (not shown) via a drive gear provided at the end of the core 117, and is driven by the drive force from the drive source in the direction of arrow R2 in FIG. 2(a). As the pressure roller 110 rotates, the fixing film 112 is rotated in the direction of arrow R3 by the frictional force it receives from the pressure roller 110 at the fixing nip N.

[0022] When the recording material P onto which the unfixed toner image T has been transferred is conveyed in the recording material conveying direction A toward the fixing nip N, the recording material P is conveyed while being sandwiched between the fixing film 112 and the pressure roller 110 at the fixing nip N. While the recording material P passes through the fixing nip N, the unfixed toner image T is pressurized, and heat from the heater 113 is transmitted to the unfixed toner image T via the fixing film 112. This causes the toner in the unfixed toner image T to melt and solidify after passing through the fixing nip N, resulting in a fixed image fixed on the surface of the recording material P.

[0023] In this embodiment, the fixing film 112 is a flexible cylindrical member (endless member) having a length of 233 mm in the longitudinal direction B and an outer diameter of 18 mm in an undeformed cylindrical state. The fixing film 112 has a multi-layer structure in the thickness direction. The fixing film 112 has a layer configuration consisting of a base layer for maintaining the strength of the film and a release layer for reducing the adhesion of dirt to the surface. The base layer must be heat-resistant to receive the heat from the heater 113 and must also be strong to slide against the heater 113, etc. Therefore, metals such as stainless steel and nickel, or heat-resistant resins such as polyimide are suitable. In this embodiment, polyimide resin is used as the material for the base layer of the fixing film 112, with a carbon-based filler added to improve thermal conductivity and strength. The thinner the base layer, the easier it is to transfer heat from the heater 113 to the surface of the pressure roller 110, but the thinner the base layer, the lower the strength. Therefore, a thickness of approximately 15 μm to 100 μm is preferred, and in this embodiment, the thickness is 60 μm.

[0024] The material for the release layer of the fixing film 112 is preferably a fluororesin such as perfluoroalkoxy resin (PFA), polytetrafluoroethylene resin (PTFE), or tetrafluoroethylene-hexafluoropropylene resin (FEP). In this embodiment, PFA, which has excellent releasability and heat resistance among fluororesins, is used as the release layer. The release layer may be formed by covering the outer periphery of a base layer with a tube or by coating the surface with paint. In this embodiment, the release layer is formed using a coating that is excellent for thin-wall molding. The thinner the release layer, the easier it is to transfer heat from the heater 113 to the surface of the fixing film 112. However, if the release layer is too thin, durability may be insufficient. Therefore, a thickness of approximately 5 μm to 30 μm is preferable, and in this embodiment, a thickness of 10 μm is used. Although not used in this embodiment, an elastic layer may be provided between the base layer and the release layer. In this case, silicone rubber, fluororubber, or the like is used as the material for the elastic layer.

[0025] A heater holder 130 is provided on the inner circumferential side of the fixing film 112 as a holding member for holding the heater 113. The heater holder 130 has a trough-shaped cross section with a substantially rectangular recess that opens toward the pressure roller 110 side (the fixing nip N side) in the vertical direction C, and extends in the longitudinal direction B. This recess also extends in the longitudinal direction B and forms a fitting groove 131 into which the heater 113 fits. The heater holder 130 has a cross section that extends in a substantially semicircular shape along the inner surface of the fixing film 112 on the upstream and downstream sides (on both sides of the fitting groove 131) of the fixing nip N in the recording material conveying direction A (see FIG. 1; FIGS. 2(a) and 2(b) show a portion of the heater holder 130). The heater holder 130 is made of a highly heat-resistant liquid crystal polymer resin to satisfy heat resistance and rigidity requirements. In this embodiment, the liquid crystal polymer resin used is Sumikasuper (registered trademark), a wholly aromatic polyester manufactured by Sumitomo Chemical Co., Ltd. The heater holder 130 not only holds the heater 113, but also serves to guide the rotation of the fixing film 112 by loosely fitting the fixing film 112 onto the heater holder 130. The heater holder 130 will be described in detail later.

[0026] The pressure stay 119 extends in the longitudinal direction B along the heater holder 130. The pressure stay 119 is made of a highly rigid sheet metal such as stainless steel that has been bent to apply uniform pressure to almost the entire area of ​​the heater holder 130 in the longitudinal direction B toward the pressure roller 110.

[0027] As shown in FIG. 2(b), fixing flanges 120, which are flange members, are fitted to both ends of the pressure stay 119 in the longitudinal direction B. The fixing flanges 120 guide (support) the rotational trajectory of the fixing film 112, regulate the end position of the fixing film 112 in the longitudinal direction B (regulate shift), and transmit pressure to the pressure stay 119. That is, each fixing flange 120 is connected to a pressure spring 122, which is an example of a pressure means that applies pressure to the fixing nip N. The pressure spring 122 is supported by a spring support portion 121 fixed to a fixing frame 124, which is the framework of the fixing device 100, and thereby urges the fixing flange 120 toward the pressure roller 110 in the vertical direction C. As a result, the pressure stay 119 connected to the fixing flange 120 is biased toward the pressure roller 110, and the heater holder 130 and heater 113 pressed by the pressure stay 119 are brought into pressure contact with the pressure roller 110 with the fixing film 112 sandwiched therebetween.

[0028] The pressure roller 110 of this embodiment is cylindrical, 220 mm long and 20 mm in outer diameter, and has a 2.5 mm thick elastic layer 116 formed around a 15 mm diameter iron core 117. The elastic layer 116 is made of solid rubber or foamed rubber. Foamed rubber has a low heat capacity and low thermal conductivity, making it difficult for heat from the surface of the pressure roller 110 to be absorbed internally. This facilitates a rise in surface temperature, which has the advantage of shortening the fixing start-up time. The fixing start-up time or warm-up time is the time required for the temperature of the fixing film 112 in the fixing nip N to reach a predetermined target temperature suitable for fixing an image after the heater 113 is turned on, starting from a state in which it is not energized. In this embodiment, foamed rubber made from foamed silicone rubber is used for the elastic layer 116.

[0029] A smaller outer diameter of the pressure roller 110 reduces heat capacity, but if it is too small, the width of the fixing nip N becomes narrow. Therefore, a moderate diameter is desirable; in this embodiment, the outer diameter is 20 mm. Regarding the thickness of the elastic layer 116, if it is too thin, heat will escape to the metal core, so a moderate thickness is also desirable. In this embodiment, the thickness of the elastic layer 116 is 2.5 mm. A release layer 118 made of perfluoroalkoxy resin (PFA) is formed on the elastic layer 116 as a toner release layer. Like the release layer of the fixing film 112, the release layer 118 can be covered with a tube or coated with paint. In this embodiment, a tube is used, which has excellent durability. In addition to PFA, the release layer 118 can also be made of fluororesins such as PTFE and FEP, or fluororubber or silicone rubber with good release properties. The lower the surface hardness of the pressure roller 110, the lighter the pressure required to obtain the wide fixing nip N. In this embodiment, a pressure roller with an Asker-C hardness (hardness measured using a type C durometer with a load of 4.9 N) of 50° was used. The pressure roller 110 is pressed against the heater by a pressure means (not shown). The total pressure is 14 kgf. In this embodiment, the width of the fixing nip N in the recording material conveyance direction A is approximately 6.0 mm over the entire area of ​​the fixing nip N in the longitudinal direction B. The pressure roller 110 is rotated by a drive source (not shown) in the direction of arrow R2 in the figure at a surface movement speed of 266 mm / sec.

[0030] The heater 113 of this embodiment is a typical heater used in film-heating fixing devices, and is configured with a resistance heating element mounted on a ceramic substrate. The heater 113 has an alumina substrate 6 mm wide in the recording material conveyance direction A and 1 mm thick in the vertical direction C. The heater 113 has an Ag / Pd (silver-palladium) resistance heating element coated on the surface of the substrate by screen printing to a thickness of approximately 10 μm, and is then covered with a 60 μm thick glass to protect the heating element and ensure its sliding properties against the inner surface of the fixing film 112. Depending on the application, a heat equalizing member with high thermal conductivity may be disposed on the back surface of the heater 113. The temperature of the heater 113 is adjusted by appropriately controlling the current flowing through the resistance heating element in response to a signal from a temperature detection element (not shown) that detects the temperature of the ceramic substrate or the fixing film 112. The heater 113 is supported (held) by the heater holder 130 by being fixed to the heater holder 130 while being fitted into a fitting groove 131 provided in the heater holder 130. In this embodiment, in order to efficiently transfer heat to the recording material P, the center (rotation axis) of the heater 113 is aligned with the center (rotation axis) of the pressure roller 110 in the recording material conveyance direction A. Note that a metal substrate such as stainless steel may be used as the substrate of the heater 113. In this case, an insulating layer such as glass is formed on the substrate, and a resistance heating element is formed on the insulating layer.

[0031] In this embodiment, fluorine-based grease is used as the lubricant applied to the sliding surface 113S of the heater 113. The sliding surface 113S is the contact surface of the heater 113 with the inner surface of the fixing film 112 (the surface on the pressure roller 110 side in the vertical direction C). Most of the sliding surface 113S is composed of the surface of a glass layer covering the resistance heating element, but a portion of the substrate may also be included in the sliding surface 113S. As the lubricant, a grease whose base oil is mainly composed of a fluorine oil such as perfluoropolyether (PFPE) and whose thickener is mainly composed of a fluorine resin powder such as polytetrafluoroethylene (PTFE) can be suitably used. The term "main component" refers to a content of 50% to 100% by mass (preferably 80% to 100% by mass). In a configuration example of this embodiment, PFPE oil is used as the base oil and PTFE powder is used as the thickener. The thickener is added and mixed in an amount of 10 to 50% by mass, preferably 15 to 40% by mass, of the total lubricant composition. Base oils will be discussed in more detail below.

[0032] 200 mg of lubricant (grease) was sprayed onto the sliding surface 113S of the heater 113 over an area of ​​210 mm, slightly shorter than the 220 mm width of the pressure region in the longitudinal direction B of the pressure roller 110. As the pressure roller 110 and the fixing film 112 rotate, the lubricant applied to the sliding surface 113S spreads around the entire inner surface of the fixing film 112, and most of it remains in the fitting groove 131 of the heater holder 130 and on the edge of the heater 113. A lubricant layer of base oil is also formed on the sliding surface 113S. The lubricant remaining in the fitting groove 131 and on the edge of the heater 113 is in a state where the base oil is held in place by the thickener, but it can penetrate and diffuse into the sliding surface 113S and into the gaps between the heater holder 130 and the heater 113 due to capillary action. Such outflow (flowing away, scattering) of the base oil due to capillary action can be suppressed by oil-repellent treatment of the fitting groove 131 or the heater 113, which will be described below.

[0033] (Base oil and oil repellent) In this embodiment, a fluorine oil such as PFPE is used as the base oil. PFPE is a polymer having perfluoroalkylene ether as a repeating unit. Specific examples of perfluoroalkylene ether include perfluoromethyl ether, perfluoroethyl ether, perfluoropropyl ether, and perfluoroisopropyl ether.

[0034] For the base oil used in a lubricant composition used in a high-temperature environment, from the viewpoint of heat resistance, a PFPE having a chemical structure in which the constituent atoms are only carbon atoms, fluorine atoms, and oxygen atoms and these atoms are bonded by single bonds can be preferably used.

[0035] Commercially available PFPEs can be used. Commercially available PFPEs include, but are not limited to, PFPEs represented by structural formula (1) (e.g., Demnum S-200, Demnum S-65 (all trade names), manufactured by Daikin Industries, Ltd.), PFPEs represented by structural formula (2) (e.g., Krytox GPL-107, Krytox GPL-106, Krytox GPL-105 (all trade names), manufactured by Chemours), PFPEs represented by structural formula (3) (e.g., Fomblin M30, Fomblin Z25 (all trade names), manufactured by Solvay Specialty Polymers), and PFPEs represented by structural formula (4) (e.g., Fomblin Y45, Fomblin Y25 (all trade names), manufactured by Solvay Specialty Polymers). In this embodiment, Fomblin M30, one of the Fomblin M series, is used.

[0036] [ka] (wherein n is a positive number, and n is a kinematic viscosity at 40°C of 10 to 300 mm 2 / s is a range number that satisfies the range.)

[0037] [ka] (wherein n is a positive number, and n is a kinematic viscosity at 40°C of 5 to 1200 mm 2 / s is a range number that satisfies the range.)

[0038] [ka] (wherein n and m are positive numbers, m / n is a number of 0.5 or more and 2 or less, and n+m is a value that indicates a kinematic viscosity at 40°C of 10 to 900 mm 2 / s is a range number that satisfies the range.)

[0039] [ka] (wherein n and m are each positive numbers, m / n is a number of 20 or more and 1000 or less, and n+m is a value that indicates a kinematic viscosity at 40°C of 10 to 700 mm 2 / s is a range number that satisfies the range.)

[0040] Regarding the base oil penetrating into the gap between components and flowing out of the lubrication target area due to capillary action, capillary action generally depends on the surface tension of the liquid, the wettability of the wall surface, the density of the liquid, and the gap. Therefore, whether the base oil penetrates into the gap between the heater holder 130 and the heater 113 depends on the wettability of the surfaces that form the gap (the surfaces of the heater holder 130 and the heater 113). In other words, if the surface is lipophilic to the base oil, penetration into the gap will be promoted, and if the surface is lipophobic to the base oil, penetration into the gap will be hindered.

[0041] As a result of extensive research, the inventors have found that it is possible to suppress the outflow of base oil due to capillary action by using a material whose contact angle with n-hexadecane is significantly different from that of base oil as an oil repellent. A material whose contact angle with n-hexadecane is significantly different from that of base oil means that the difference (absolute value of γ1 - γ2) between the contact angle with n-hexadecane (γ1) when the agent is applied to a component surface and the contact angle with n-hexadecane (γ2) when base oil is applied to the component surface is large.

[0042] Surface tension and surface free energy can be divided into dispersive, polar, and hydrogen-bonding components, respectively, and it is known that the closer the values ​​of these components are to each other, the better they will wet. PFPE, the base oil of the lubricant used in this study, is non-polar and does not contain hydrogen atoms, so the dispersive component of its surface free energy is dominant. Furthermore, the hexadecane used in the evaluation had a surface tension of 27.6 mN / m, with a dispersive component of 27.6 mN / m and a polar component of 0.0 mN / m, meaning the dispersive component is dominant.

[0043] Therefore, when selecting an oil repellent to suppress the outflow of base oil due to capillary action, it is considered preferable to focus on the dispersion component of surface free energy and select a material whose contact angle measured with hexadecane is significantly different from that of the base oil. The oil repellency of a component surface to a base oil can be directly evaluated by measuring the contact angle when a drop of base oil is applied to the component surface, and it has been found that the magnitude of this contact angle shows a high correlation with the magnitude of the difference in the contact angle of hexadecane to the base oil. Therefore, in this disclosure, the oil repellency of a surface coated with an oil repellent to a base oil is evaluated based on the difference in the contact angle of hexadecane to the base oil.

[0044] In order to prevent the base oil from leaking due to capillary action, in this embodiment, a treatment (oil-repellent treatment) is performed on the surface of a component that forms a gap through which the base oil can penetrate, to enhance the oil repellency against the base oil. As for the oil-repellent treatment, as described above, an oil-repellent agent having a hexadecane contact angle significantly different from that of the base oil is applied to the component surface, and also, a method of providing a fine uneven structure on the component surface (lotus effect) is conceivable. Of these, the method of applying an oil-repellent agent is advantageous in terms of manufacturing costs, etc.

[0045] There are two main methods for applying an oil repellent. One is to apply the oil repellent directly to the surface of a component, and the other is to apply an oil repellent such as a silane coupling agent (an oil repellent that reacts with the surface of the component to modify it) to the surface of the component and then bake it. In this embodiment, we have considered two examples: one in which an oil repellent whose main component is silicone oil is applied to the fitting groove 131 of the heater holder 130, and another in which an oil repellent whose main component is a silane coupling agent is applied to the fitting groove 131 and then baked.

[0046] The silicone oil used for the surface treatment of the heater holder 130 as the oil repellent according to this embodiment is preferably polysiloxane, more preferably dimethylpolysiloxane. The molecular weight of the silicone oil is preferably 10,000 or more and 100,000 or less, more preferably 20,000 or more and 70,000 or less. By using a silicone oil with a molecular weight of 100,000 or less, the dynamic viscosity at 25°C can be increased, thereby preventing the oil repellent from leaking. The silicone oil may be composed of multiple types of silicone oil.

[0047] Suitable for silicone oils, with a kinematic viscosity of 200mm at 25°C 2 The commercially available silicone oil with a kinematic viscosity of 1,000 mm / s or more is KF-965-1,000cs (kinematic viscosity at 25°C of 1,000 mm). 2 / s), KF-965-10,000cs (kinematic viscosity at 25°C 10,000mm 2 / s) (both manufactured by Shin-Etsu Chemical Co., Ltd.), DOWSIL SH 200 Fluid 2,000cSt (kinematic viscosity at 25°C 2,000mm 2 / s), DOWSIL SH 200 CV Fluid 13,000cSt (kinematic viscosity at 25°C 13,000mm 2 / s) (all manufactured by Toray Dow Corning), etc.

[0048] The silane coupling agent used in the surface treatment of the heater holder as the oil repellent according to this embodiment is represented by the general formula (A). R m-Si-Y n (a) (In the formula, R represents an alkoxy group, m represents an integer of 1 to 3, and Y represents an organic functional group such as an alkyl group, a vinyl group, a glycidoxy group, a methacryl group, an amino group, or an epoxy group. That is, Y represents an organic functional group that does not contain a fluoro group and has low affinity for the fluorine oil that is the base oil. n represents an integer of 1 to 3, with the proviso that m+n=4.)

[0049] Examples of the silane coupling agent represented by the general formula (A) include vinyltrimethoxysilane, vinyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, n-butyltriethoxysilane, isobutyltriethoxysilane, trimethylmethoxysilane, hexyltrimethoxysilane, decyltrimethoxysilane, 3-hydroxypropyltriethoxysilane, hexadecyltrimethoxysilane, and octadecyltrimethoxysilane.

[0050] Among these, from the viewpoint of obtaining high hydrophobicity, it is preferable to use an alkyltrialkoxysilane coupling agent represented by the following general formula (A). C p H 2p+1 -Si-(OC q H 2q+1 )3(I) (In the formula, p represents an integer of 1 or more and 10 or less, and q represents an integer of 1 or more and 3 or less.)

[0051] As p in the above formula (A) becomes larger, oil repellency decreases (the hexadecane contact angle increases), so p is preferably 1 or more and 10 or less. Furthermore, if q is greater than 3, the reactivity of the silane coupling agent decreases, which may make it difficult to achieve sufficient oil repellency treatment. Therefore, it is preferable to use an alkyltrialkoxysilane coupling agent in which p in the formula is an integer of 1 or more and 10 or less (more preferably, an integer of 1 or more and 5 or less) and q is an integer of 1 or more and 3 or less (more preferably, an integer of 1 or 2).

[0052] When the above-mentioned silane coupling agents are used, they can be used alone or in combination with a plurality of types. When they are used in combination, each coupling agent can be used individually or simultaneously.

[0053] Commercially available silane coupling agents suitable as oil repellents include KBE-13 (methyltriethoxysilane), KBE-22 (dimethyldiethoxysilane), KBE-3083 (octyltriethoxysilane), KBM-13 (methyltrimethoxysilane) (all manufactured by Shin-Etsu Chemical Co., Ltd.), XIAMETER OFS-6366 Silane (methyltrimethoxysilane), XIAMETER OFS-6383 Silane (methyltriethoxysilane) (all manufactured by Dow-Toray Industries, Inc.), and M0451 (methyltrimethoxysilane) (all manufactured by Tokyo Chemical Industry Co., Ltd.).

[0054] In the present disclosure, the contact angle was measured by measuring the contact angle of normal hexadecane (n-hexadecane) on the oil-repellent treated surface of the heater holder 130. A contact angle meter (product name: DM-501, manufactured by Kyowa Interface Science Co., Ltd.) was used to measure the contact angle (measurement environment: temperature 23°C, relative humidity 55%).

[0055] (oil repellent treatment) The area to be treated with the oil-repellent treatment in this embodiment will be described with reference to FIG. 3. FIG. 3 is a cross-sectional view of the fixing device 100 showing the heater holder 130 and its periphery. The heater 113 is fitted and fixed in a fitting groove 131 of the heater holder 130, and a necessary gap is set between the heater 113 and the fitting groove 131 to take into account thermal expansion of the heater 113 due to heating. In this embodiment, the width of the heater 113 in the recording material conveyance direction A is 5.8 mm, while the width of the fitting groove 131 in the heater holder 130 is set to 6.45 mm. A gap 132 of 0.35 mm is provided between the side surface 113 a of the heater 113 on the upstream side in the recording material conveyance direction A and the wall surface 131 a of the fitting groove 131. A gap 132 of 0.30 mm is also provided between the side surface 113 a of the heater 113 on the downstream side in the recording material conveyance direction A and the wall surface 131 a of the fitting groove 131. The side surface 113a of the heater 113 is the side surface of the substrate of the heater 113.

[0056] When the base oil of the lubricant penetrates and diffuses into this gap 132 due to capillary action, the base oil of the lubricant present between the sliding surface 113S of the heater 113, which is the object to be lubricated, and the inner surface of the fixing film 112 gradually flows out, causing an increase in the sliding friction resistance of the fixing film 112. To prevent this phenomenon, in this embodiment, an oil-repellent treatment is performed by applying an oil-repellent agent to the inner surface of the fitting groove 131 of the heater holder 130.

[0057] The oil repellent is applied to at least a portion of the wall surface 131a and bottom surface 131b, which are the inner surfaces of the fitting groove 131. In the longitudinal direction B, the oil repellent is applied to at least a portion of the range where the sliding surface 113S of the heater 113 slides against the inner surface of the fixing film 112 (a film contact area Lf described below, see Figures 7(b) and 7(c)). Preferably, the oil repellent is applied over the entire area where the lubricant is applied in the longitudinal direction B in the initial state (factory-shipped state) (a lubricant application area Lg described below). More preferably, the oil repellent is applied over the entire film contact area Lf. In this embodiment, the oil repellent is applied over the entire area of ​​the fitting groove 131 in the longitudinal direction B. The portion to which oil repellency is imparted by applying the oil repellent is referred to as an oil repellent treated portion AP (see the hatched area of ​​the heater holder 130).

[0058] The oil-repellent treated portion AP to which the oil repellent agent is applied functions as an oil-repellent portion that exhibits oil repellency to the base oil of the lubricant. "Exhibiting oil repellency to the base oil of the lubricant" means that the contact angle of the base oil with the treated surface is larger than the contact angle of the base oil with the untreated surface of the target component (here, the surface of the liquid crystal polymer that constitutes the heater holder 130).

[0059] As for the application method, known application methods such as spray application, brush application, and dipping can be used. The oil repellent may be diluted depending on the application method. When diluting, it is preferable to select a diluent taking into consideration that the oil repellent is sufficiently dissolved and that the diluent can be easily removed.

[0060] In the configuration example of this embodiment, the oil repellent treatment was performed by spraying silicone oil onto the heater holder 130. In another configuration example, a silane coupling agent was diluted 5 times with an alcohol aqueous solution (water / alcohol = 1 / 9 parts by weight), sprayed onto the heater holder 130, and dried in a heating furnace at 120°C for 30 minutes.

[0061] (Oil-repellent treatment effect) Next, the effect of the oil-repellent treatment of this embodiment will be explained in comparison with a comparative example using Figures 4(a) to 4(c). Figure 4(a) is a schematic diagram showing the initial penetration of lubricant G and base oil Gb in a conventional example in which the heater holder 130 is not oil-repellent treated. Figure 4(b) is a schematic diagram showing the initial penetration of lubricant G and base oil Gb in a comparative example in which a lipophilic agent is applied to the fitting groove 131 of the heater holder 130. Figure 4(c) is a schematic diagram showing the initial penetration of lubricant G and base oil Gb in this embodiment in which a lipophobic agent is applied to the fitting groove 131 of the heater holder 130.

[0062] When the fixing device 100 is operated after applying the lubricant G to the sliding surface 113S of the heater 113, the lubricant G moves with the rotation of the fixing film 112 and adheres to the heater holder 130, etc., and the base oil Gb spreads over the sliding surfaces (the inner surface of the fixing film 112 and the sliding surface 113S). Even when the fixing device 100 is not operated after applying the lubricant during assembly of the fixing device 100, the lubricant G is crushed in the fixing nip N and protrudes to the upstream and downstream sides of the heater 113 in the recording material conveyance direction A. In either case, the base oil Gb comes into contact with the gap 132 between the heater holder 130 and the heater 113.

[0063] Generally, capillary action depends on the surface tension of the liquid, the wettability of the wall surface, the density of the liquid, and the gap. Therefore, whether the base oil Gb constituting the lubricant G can easily penetrate the gap 132 depends on the wettability of the wall surface 131a of the heater holder 130 and the side surface 113a of the heater 113, which form the gap 132. In the conventional example, when the base oil Gb initially contacts the gap, as shown in FIG. 4A, the base oil Gb adheres only to a small portion of the wall surface 131a of the heater holder 130 and the side surface 113a of the heater 113. However, as the cumulative usage time of the fixing device 100 increases or as time passes after assembly, the base oil Gb penetrates deeper into the gap 132 while wetting the wall surface 131a and the side surface 113a. Therefore, the base oil Gb is gradually lost to the space between the heater 113 and the heater holder 130, and flows out to the inside of the fixing film 112 and the sliding surface 113S of the heater 113, which are the objects to be lubricated.

[0064] For comparison, Figure 4(b) shows the heater holder 130 fitted with a mating groove 131 coated with a material (lipophilic agent) exhibiting lipophilicity toward the base oil Gb. The lipophilic agent used here is a silane coupling agent with a fluoroalkyl group (triethoxy-1H,1H,2H,2H-heptadecafluorodecylsilane, T2876, manufactured by Tokyo Chemical Industry Co., Ltd.). Surface treatment with fluorine can lower surface free energy and is therefore sometimes mistakenly perceived as liquid-repellent. However, the surface (lipophilic treatment area) treated with the fluorine oil (base oil Gb) and the silane coupling agent with a fluoroalkyl group exhibit lipophilicity and is easily wetted, as their contact angles with hexadecane are similar. Therefore, in this comparative example, the penetration and diffusion of the base oil Gb into the gap 132 is promoted, resulting in a greater amount of the base oil Gb leaking out of the lubrication target area in a short period of time.

[0065] On the other hand, in this embodiment, an oil repellent agent is applied to the inner surface (particularly, wall surface 131a) of fitting groove 131 of heater holder 130, and the initial state in which base oil Gb comes into contact with gap 132 is as shown in FIG. 4(c). As shown in the figure, since wall surface 131a of fitting groove 131 is oil repellent to base oil Gb, capillary action is unlikely to occur, and intrusion of base oil Gb into gap 132 is inhibited. As a result, even if the cumulative usage time of fixing device 100 increases or the time that has passed since assembly increases, the outflow of base oil Gb through gap 132 due to capillary action is suppressed, and the lubricating effect of lubricant G can be stably obtained over a long period of time.

[0066] Examples of oil repellents that can be applied to the mating groove 131 of the heater holder 130 include KF-965-1,000cs (manufactured by Shin-Etsu Chemical Co., Ltd.), DOWSIL SH 200 Fluid 2,000cSt (manufactured by Dow-Toray Industries, Inc.), KBE-13 (methyltriethoxysilane), KBE-22 (dimethyldiethoxysilane), KBE-3083 (octyltriethoxysilane), and KBM-13 (methyltrimethoxysilane) (all manufactured by Shin-Etsu Chemical Co., Ltd.).

[0067] (Comparative experiment) A comparative experiment was conducted to confirm the effectiveness of the oil-repellent treatment. A conventional fixing device 100 without an oil-repellent or lipophilic agent applied to the fitting groove 131 of the heater holder 130 and a fixing device 100 with materials having different hexadecane contact angles applied to the fitting groove 131 of the heater holder 130 were prepared. These fixing devices 100 were assembled into an image forming apparatus 50, and a paper-feed durability test was conducted in which image formation (paper feeding) was performed on a large number of recording materials to compare the durability of the fixing devices 100. In an office environment (temperature 23°C, relative humidity 50%), intermittent paper feeding was performed with a predetermined interval between each sheet of recording material, and the number of sheets that could be passed before image defects or malfunctions of the fixing device 100 occurred was compared. Table 1 shows the materials used as the oil-repellent or lipophilic agent and the durability evaluation results of the fixing device 100. In Table 1, the number of sheets of recording material that could be passed without causing image defects or operational malfunctions that exceeded the acceptable range is defined as the number of sheets that could be passed, and a clear increase in the number of sheets that could be passed compared to the conventional example is marked with an "O", and a slight increase in the number of sheets that could be passed is marked with a "△".

[0068] [Table 1]

[0069] In the conventional example, the heater holder 130 is made of a liquid crystal polymer, and the inner surface of the fitting groove 131 is also made of this liquid crystal polymer. In this case, the contact angle γ of hexadecane with the liquid crystal polymer surface is 36.2°. On the other hand, the contact angle γ of hexadecane with the surface of the liquid crystal polymer, which is the heater holder 130 material, coated with base oil Gb, is 61.9°. Therefore, the difference (Δγ) in the contact angle of hexadecane with the base oil on the surface of the heater holder 130 without the oil-repellent or lipophilic agent is 25.7°. In this conventional example, when the number of sheets passed exceeded 200,000, image defects or operational malfunctions beyond the acceptable range occurred. In other words, the number of sheets that the fixing device 100 in the conventional example could pass was 200,000.

[0070] In a comparative example in which a silane coupling agent T2876 having a fluorinated alkyl group exhibiting lipophilicity toward the base oil was applied, the hexadecane contact angle γ on the surface of the heater holder 130 was 63.0°, and the difference in the contact angle of hexadecane with the base oil (Δγ) was 1.1°. In this comparative example, the paper throughput was 130,000 sheets, significantly lower than the conventional example. This indicates that the lipophilicity of the surface of the engagement groove 131 toward the base oil Gb promoted the penetration of the base oil Gb into the gap 132 by capillary action. Furthermore, this indicates that the penetration of the base oil Gb into the gap 132 caused the base oil Gb to be removed from the sliding surface 113S of the heater 113 and the inner surface of the fixing film 112, which were intended to be lubricated, resulting in the depletion of the lubricant G.

[0071] In contrast, when silicone oil (oil repellents 1 and 2) according to the present embodiment was applied, the difference in the contact angle (Δγ) between the base oil and the hexadecane was 41.3° or 41.8°, which was larger than the Δγ of the conventional examples. In these examples, the number of sheets that could be passed through was 270,000, a significant increase compared to the conventional examples, indicating a significant improvement in durability. Furthermore, when the silane coupling agents shown in oil repellents 3 to 6 were applied and baked, the difference in the contact angle (Δγ) between the base oil and the hexadecane was 35.1° to 38.1°, which was larger than the Δγ of the conventional examples. In these examples, the number of sheets that could be passed through was 240,000 to 245,000, an increase compared to the conventional examples, indicating an improvement in durability.

[0072] However, when the heater holder 130 was oil-repellent treated with the silane coupling agent KBE-903 shown as oil-repellent agent 7, the difference in the contact angle of hexadecane with the base oil (Δγ) was 27.0°, only a slight increase compared to the conventional example (25.7°). Furthermore, when oil-repellent agent 7 was used, the number of sheets that could be passed was 205,000, only a slight increase compared to the conventional example.

[0073] As the above results show, by applying an oil repellent agent that is oil repellent to the base oil Gb to the inner surface of the fitting groove 131 of the heater holder 130, it is possible to prevent the base oil Gb from leaking out of the lubrication target area due to capillary action. This prevents the depletion of the lubricant G, and maintains the performance of the fixing device 100 over a long period of time. Furthermore, the results of the comparative experiment show that a material with a large difference in contact angle (Δγ) between the base oil Gb and hexadecane is preferable for the oil repellent agent to be applied to the fitting groove 131. Specifically, an oil repellent agent with Δγ of 35.0° or more is preferable. Furthermore, according to Table 1, an oil repellent agent with Δγ of 40.0° or more is more preferable.

[0074] Second Embodiment A second embodiment of the present disclosure will be described below. The second embodiment differs from the first embodiment in the range to which the oil repellent is applied. Hereinafter, elements with the same reference symbols as those in the first embodiment will be considered to have substantially the same configurations and functions as those described in the first embodiment, and elements that differ from the first embodiment will be mainly described.

[0075] The application area of ​​the oil repellent and its action in this embodiment will be described with reference to Figures 5(a) and 5(b). In the first embodiment, the oil repellent was applied to the inner surface of the fitting groove 131 of the heater holder 130, but in this embodiment, as shown in Figure 5(a), the oil repellent is applied not only to the inner surface of the fitting groove 131 but also to the side surface 113a of the heater 113. In other words, the oil repellent treatment area AP, which is the oil repellent portion in this embodiment, includes the wall surface 131a and bottom surface 131b of the fitting groove 131 and the side surface 113a of the heater 113 in the recording material conveyance direction A.

[0076] FIG. 5B is a schematic diagram showing the state of the lubricant G and the base oil Gb in this embodiment. In this embodiment, the oil repellent is applied not only to the fitting groove 131 of the heater holder 130 but also to the side surface 113a of the heater 113, which is the surface facing the wall surface 131a of the fitting groove 131. Therefore, in the initial state in which the base oil Gb comes into contact with the gap 132, as shown in FIG. 5B, capillary action is even less likely to occur than in the first embodiment (FIG. 4C), and the base oil Gb is prevented from entering the gap 132. As a result, even if the cumulative usage time of the fixing device 100 increases or the time elapsed since assembly increases, the outflow of the base oil Gb through the gap 132 due to capillary action is suppressed, and the lubricating effect of the lubricant G can be stably obtained over a long period of time.

[0077] In the first embodiment, an oil repellent is applied to the fitting groove 131 of the heater holder 130 to prevent the base oil Gb from flowing out due to capillary action in the gap 132 between the heater 113 and the heater holder 130. However, the capillary action in the gap 132 can also be affected by the side surface 113a of the heater 113. Here, if a liquid (silicone oil) is applied to the fitting groove 131 as the oil repellent, the oil repellent itself can fill the gap 132 due to capillary action, preventing the base oil Gb from entering the gap 132. In this case, by applying the oil repellent, the side surface 113a of the heater 113 that forms the gap 132 also functions as an oil repellent treatment portion.

[0078] On the other hand, if an oil-repellent agent such as a silane coupling agent is applied to the inner surface of the fitting groove 131 and then baked, the side surface 113a of the heater 113 is not oil-repellent treated, and therefore, depending on conditions such as the width and depth of the gap 132, it may be possible for the base oil Gb to penetrate.

[0079] In this embodiment, since the oil-repellent treatment is performed not only on the fitting groove 131 of the heater holder 130 but also on the side surface of the heater 113, it is effective to use an oil-repellent agent that imparts oil repellency by modifying the surface of a member, such as a silane coupling agent. Therefore, for the silane coupling agent that improved the durability of the fixing device 100 in the first embodiment, the application conditions of this embodiment were applied, and an experiment similar to the comparative experiment described in the first embodiment was conducted. Table 2 shows the results of the comparative experiment for each material between the configuration of the first embodiment and the configuration of this embodiment.

[0080] [Table 2]

[0081] From Table 2, it can be seen that, regardless of which material is used as the oil repellent, the durability of the fixing device 100 is improved compared to the first embodiment by applying the configuration of this embodiment in which the oil repellent is also applied and baked on the side surface 113a of the heater 113. In other words, from the perspective of maintaining the performance of the fixing device 100 for a longer period of time, it is preferable to apply the oil repellent treatment to both the inner surface of the fitting groove 131 that forms the gap 132 between the heater holder 130 and the heater 113 and the side surface 113a of the heater 113.

[0082] (Variation) In the first embodiment, only the heater holder 130 is subjected to the oil-repellent treatment, and in the second embodiment, both the heater holder 130 and the heater 113 are subjected to the oil-repellent treatment, but as a modified example, it is also possible to apply the oil-repellent treatment only to the heater 113. Even in this case, by imparting oil repellency to the base oil Gb to the side surface 113a of the heater 113, it is possible to suppress the intrusion of the base oil Gb into the gap 132 between the heater holder 130 and the heater 113 and reduce the outflow of the base oil Gb.

[0083] <Third embodiment> A third embodiment of the present disclosure will be described below. In the third embodiment, the components of the base oil Gb are different from those in the first embodiment, and the oil repellent is also changed accordingly. Hereinafter, elements with the same reference symbols as those in the first embodiment will be considered to have substantially the same configurations and functions as those described in the first embodiment, and elements that differ from the first embodiment will be mainly described.

[0084] In the first and second embodiments, fluorine oil is used as the main component of the base oil Gb of the lubricant G. Fluorine oil has the advantage of providing high slidability and durability in high-temperature environments, but silicone oil may also be used as the base oil Gb depending on the temperature range and other conditions used. Even when silicone oil is used as the main component of the base oil Gb, if the base oil Gb leaks out due to capillary action in the gap 132 between the heater holder 130 and the heater 113, problems such as increased sliding friction resistance may occur. Therefore, when silicone oil is used as the base oil Gb, it is effective to apply an oil-repellent treatment to the fitting groove 131 of the heater holder 130 and the side surface 113a of the heater 113 to increase the oil repellency against silicone oil.

[0085] The oil repellent of this embodiment may be a fluorine oil such as perfluoropolyether or a silane coupling agent having a fluorinated functional group. The coupling agent that can be used as the oil repellent of this embodiment is represented by the general formula (C). R m -Si-X n (cormorant) (In the formula, R represents an alkoxy group, m represents an integer of 1 to 3, X represents an organic functional group such as a fluorinated alkyl group (i.e., an organic functional group containing a fluoro group that has low affinity for the silicone oil base oil), and n represents an integer of 1 to 3, with the proviso that m+n=4.)

[0086] Examples of the silane coupling agent represented by the general formula (c) include trifluoropropyltrimethoxysilane.

[0087] Table 3 shows the hexadecane contact angle and the evaluation results of the paper passing durability test when silicone oil, which is the base oil Gb in this embodiment, and each material used as an oil repellent or lipophilic agent are applied to the heater holder 130. Fomblin M30, the oil repellent 1, was applied to the fitting groove 131 of the heater holder 130, and the silane coupling agents, oil repellents 2 and 3 and lipophilic agents 1 to 4, were applied to both the fitting groove 131 of the heater holder 130 and the side surface 113a of the heater 113, and then baked.

[0088] [Table 3]

[0089] As shown in Table 3, the contact angle γ of hexadecane on the surface of the liquid crystal polymer (conventional example) without any application of an oil-repellent or lipophilic agent is 36.2°. On the other hand, the contact angle γ of hexadecane on the surface of the liquid crystal polymer, the material of the heater holder 130, applied with silicone oil, the base oil Gb of this embodiment, is 20.6°. Therefore, the difference (Δγ) in the contact angle of hexadecane on the surface of the heater holder 130 without any application of an oil-repellent or lipophilic agent with respect to the base oil Gb is 15.6°. In this conventional example, when the number of sheets passed exceeded 150,000, image defects or operational malfunctions beyond the acceptable range began to occur.

[0090] When a silane coupling agent (lipophilic agents 1-4) exhibiting lipophilicity toward the base oil Gb was applied to the fitting groove 131 of the heater holder 130, the hexadecane contact angle γ on the surface of the heater holder 130 was 26.8° to 34.9°. Therefore, the difference in the contact angle (Δγ) between the hexadecane and the base oil Gb in this embodiment was 6.2° to 14.3°, smaller than the Δγ of the conventional example. In these examples, the number of sheets that could be passed was 140,000 to 145,000, a significant decrease compared to the conventional example. This indicates that the lipophilic agent promoted the penetration and diffusion of the base oil Gb into the gap 132 between the heater holder 130 and the heater 113, causing the lubricant G to be depleted more quickly than in the conventional example.

[0091] When oil repellents 1 to 3, which are oil repellent to the base oil Gb of this embodiment, were used, the difference in contact angle (Δγ) between hexadecane and the base oil Gb was 39.0° to 42.4°, which was larger than the Δγ of the conventional example. In these examples, the number of sheets that could be passed was 260,000 to 270,000, which was a significant increase compared to the conventional example, and it can be said that durability was greatly improved.

[0092] As the above results show, even if the components of the base oil Gb are different from those in the fifth embodiment, by applying an oil repellent that is oil repellent to the base oil Gb to the inner surface of the fitting groove 131 of the heater holder 130 and the side surface of the heater 113, it is possible to prevent the base oil Gb from leaking out of the lubrication target area. This prevents the depletion of the lubricant G and maintains the performance of the fixing device 100 for a long period of time. Furthermore, according to the results in Table 3, it is preferable that the oil repellent to be applied to the fitting groove 131 be one in which the difference in contact angle (Δγ) between the base oil Gb and hexadecane is 35.0° or more.

[0093] <Fourth embodiment> A fourth embodiment of the present disclosure will be described. In this embodiment, a basic configuration of a fixing device different from that of the first to third embodiments will be described. Hereinafter, elements with the same reference numerals as those in the first embodiment will be considered to have substantially the same configuration and function as those described in the first embodiment, and elements different from those in the first embodiment will be mainly described.

[0094] FIG. 6A shows a fixing device including a hollow fixing roller 114 with a halogen lamp HL disposed therein and a pressure unit including a pressure film 115, a sliding plate 140, and a sliding plate holding member 141. The fixing roller 114 is a heating member that heats an image on a recording material in the fixing nip. The sliding plate 140 is held by the sliding plate holding member 141 while being fitted into a fitting groove 142 provided in the sliding plate holding member 141, and slides against the inner surface of the pressure film 115 via a lubricant. The sliding plate holding member 141 is pressed toward the fixing roller 114 by a pressure means (not shown), thereby forming a fixing nip between the sliding plate 140 and the fixing roller 114. In this fixing device, the fixing roller 114, heated by radiant heat from the halogen lamp HL, fixes the image on the recording material while sandwiching and transporting the recording material between the fixing roller 114 and the pressure film 115 in the fixing nip.

[0095] 6B shows a film-heating type fixing device using a halogen lamp HL as a heat source. This fixing device includes a cylindrical fixing film 112 having a halogen lamp HL, a sliding plate 143, and a sliding plate holding member 144 disposed therein, and a pressure roller 110 that presses against the sliding plate 143 while sandwiching the fixing film 112. The sliding plate 143 is held by the sliding plate holding member 144 while being fitted into a fitting groove 145 provided in the sliding plate holding member 144, and slides against the inner surface of the fixing film 112 via a lubricant. The sliding plate holding member 144 is pressed against the pressure roller 110 by a pressure means (not shown), thereby forming a fixing nip between the sliding plate 143 and the pressure roller 110. In this fixing device, the fixing film 112 is heated by radiant heat from the halogen lamp HL while conveying a recording material sandwiched between the fixing film 112 and the pressure roller 110 in the fixing nip.

[0096] As yet another configuration, in the fixing device 100 shown in the first embodiment, a sliding plate placed over the heater 113 is fitted into the fitting groove 131 (see FIG. 2(a)) of the heater holder 130 together with the heater 113. This sliding plate is arranged for the purpose of improving the slidability of the fixing film 112 or making the temperature distribution in the longitudinal direction B in the fixing nip uniform. In this case, a lubricant is applied to the sliding surface of the sliding plate that slides against the fixing film 112, and adheres to the gap between the sliding plate and the fitting groove 131 of the heater holder 130, which serves as a sliding plate holding member.

[0097] In these configurations, as explained in the first to third embodiments, the base oil of the lubricant may leak out due to capillary action through the gap between the sliding plate and the fitting groove of the sliding plate holding members 141, 144 that hold the sliding plate. Therefore, by applying an oil-repellent treatment, such as applying an oil-repellent agent that repels the base oil, to the fitting groove of the sliding plate holding members 141, 144 and / or the side surface of the sliding plate, it is possible to prevent the base oil from leaking out due to capillary action. This makes it possible to maintain the performance of the fixing device over a long period of time.

[0098] Fifth Embodiment A fifth embodiment of the present disclosure will be described below. The fifth embodiment differs from the first embodiment in the range to which the oil repellent is applied. Hereinafter, elements with the same reference symbols as the first embodiment will be considered to have substantially the same configurations and functions as those described in the first embodiment, and elements that differ from the first embodiment will be mainly described.

[0099] In the first to fourth embodiments, a configuration has been described in which the base oil can be prevented from flowing out due to capillary action through a gap between the heater or the sliding plate and the heater holder or the sliding plate holding member that holds it. In the present embodiment, a configuration will be described in which the base oil can be prevented from spreading in the longitudinal direction due to capillary action through a gap between the heater and the heater holder that holds it, and from flowing out (leaking) from the longitudinal end of the fixing film.

[0100] If the base oil of the lubricant, which is normally present inside the fixing film, flows around the longitudinal end of the fixing film and leaks out to the outside of the fixing film, the following problems may occur: For example, the base oil may contaminate the recording material in the fixing nip, causing poor conveyance, or the release layer of the pressure roller may swell with the base oil, causing cracks. Furthermore, because the base oil is taken away from the areas that are intended to be lubricated (the heater sliding surface and the inner surface of the fixing film), depletion of the base oil may cause a deterioration in the performance of the fixing device, as described in the first to fourth embodiments.

[0101] Therefore, in this embodiment, an oil repellent agent that is oil repellent to the base oil of the lubricant is applied to both longitudinal ends of the fitting groove 131 of the heater holder 130 into which the heater 113 is fitted as an oil repellent treatment. The method of selecting the oil repellent agent and the method of applying the oil repellent agent are the same as those in the first embodiment, so a description thereof will be omitted. Also, as in the first embodiment, an oil repellent treatment that enhances the oil repellency to the base oil may be performed by providing a fine uneven structure (lotus effect) on the surface of the component.

[0102] The oil-repellent treatment in this embodiment will be described with reference to FIGS. 7(a) to 7(c). FIG. 7(a) is a cross-sectional view of the heater holder 130 and its periphery taken along a plane perpendicular to the longitudinal direction B. FIG. 7(b) is a view of the heater holder 130 and the heater 113 viewed from the fixing nip N side in the vertical direction C. FIG. 7(c) is a view of the heater holder 130 from which the heater 113 has been removed, viewed from the same direction as FIG. 7(b), illustrating the oil-repellent treatment area AP to which an oil-repellent agent has been applied. In FIGS. 7(b) and 7(c), the area where the fixing film 112 contacts the heater 113 in the longitudinal direction B of the fixing device 100 is referred to as a film contact area Lf, and the area where the lubricant is applied to the heater 113 is referred to as a lubricant application area Lg. Similarly, the area where the lubricant is applied to the heater holder 130 in the longitudinal direction B of the fixing device 100 is referred to as an oil-repellent application area Lr. The nip pressure region Lp is the region where the pressure roller 110 is pressed against the heater 113 with the fixing film 112 sandwiched therebetween. As described above, the lubricant application region Lg is located inside the nip pressure region Lp in the longitudinal direction B, and is set to a length (210 mm) slightly shorter than the length (220 mm) of the pressure roller 110.

[0103] As in the first embodiment, a necessary gap is set between the heater 113 and the fitting groove 131 of the heater holder 130 in consideration of thermal expansion of the heater 113 due to heating (FIGS. 7A and 7B). In this embodiment, the width of the heater 113 in the recording material conveyance direction A is 5.8 mm, while the width of the fitting groove 131 of the heater holder 130 is set to 6.45 mm. A gap 132 of 0.35 mm is provided between the side surface 113a of the heater 113 on the upstream side in the recording material conveyance direction A and the wall surface 131a of the fitting groove 131. In addition, a gap 132 of 0.30 mm is provided between the side surface 113a of the heater 113 on the downstream side in the recording material conveyance direction A and the wall surface 131a of the fitting groove 131.

[0104] If the base oil of the lubricant moves in the longitudinal direction B through this gap 132 due to capillary action and spreads to the outside of the end of the fixing film 112 in the longitudinal direction B, the base oil may wrap around the outer surface of the fixing film 112, causing the above-mentioned problems. To prevent the base oil from leaking out due to capillary action, an oil repellent is applied to at least one end, preferably both ends, of the fitting groove 131 of the heater holder 130 in the longitudinal direction B (FIG. 7(c)). To effectively prevent the base oil from leaking around both ends of the fixing film in the longitudinal direction B, the oil repellent is applied to an area extending from both outsides of the film contact area Lf to the inside of the film contact area Lf in the longitudinal direction B. In this embodiment, the entire area of ​​the fitting groove 131 outside the lubricant application area Lg, indicated by the diagonal lines in FIG. 7(c), is designated as the oil repellent application area Lr, and the oil repellent is applied thereto. In this case, the inner edge of the lube repellent application area Lr and the outer edge of the nip pressure area Lp overlap.

[0105] As for the application method, known application methods such as spray application, brush application, and dipping can be used. The oil repellent may be diluted depending on the application method. When diluting, it is preferable to select a diluent taking into consideration that the oil repellent is sufficiently dissolved and that the diluent can be easily removed.

[0106] In the configuration example of this embodiment, the oil repellent treatment was performed by spraying silicone oil onto the heater holder 130. In another configuration example, a silane coupling agent was diluted 5 times with an alcohol aqueous solution (water / alcohol = 1 / 9 parts by weight), sprayed onto the heater holder 130, and dried in a heating furnace at 120°C for 30 minutes.

[0107] (Oil-repellent treatment effect) Next, the effect of the oil-repellent treatment of this embodiment on the lubricant G and base oil Gb will be explained, comparing it with a comparative example using Figures 8(a) to 8(c). Figure 8(a) is a diagram showing the heater 113 fitted into the heater holder 130, with the lubricant G applied to the lubricant application area Lg. The bottom of Figure 8(a) shows an enlarged view of the boundary of the lubricant application area Lg. Figure 8(b) is a schematic diagram showing the initial penetration of the lubricant G and base oil Gb at the boundary of the lubricant application area Lg in a conventional example in which the heater holder 130 is not oil-repellent treated. Figure 8(c) is a schematic diagram showing the initial penetration of the lubricant G and base oil Gb at the boundary of the lubricant application area Lg in a comparative example in which an oleophilic agent is applied to both longitudinal ends of the fitting groove 131 of the heater holder 130. Figure 8(d) is a schematic diagram showing the initial penetration of lubricant G and base oil Gb at the boundary of the lubricant application area Lg in this embodiment in which oil repellent is applied to both longitudinal ends of the fitting groove 131 of the heater holder 130.

[0108] When the fixing device 100 is operated after applying the lubricant G to the sliding surface 113S of the heater 113, the lubricant G moves with the rotation of the fixing film 112 and adheres to the heater holder 130, etc., and the base oil Gb spreads over the inner surface of the fixing film 112 and the sliding surface 113S of the heater 113. Even when the fixing device 100 is not operated after applying the lubricant during assembly of the fixing device 100, the lubricant G is crushed in the fixing nip N and protrudes to the upstream and downstream sides of the heater 113 in the recording material conveyance direction A. In either case, the base oil Gb comes into contact with the gap 132 between the heater holder 130 and the heater 113.

[0109] Generally, capillary action depends on the surface tension of the liquid, the wettability of the wall surface, the density of the liquid, and the gap. Therefore, whether the base oil Gb constituting the lubricant G can easily penetrate the gap 132 depends on the wettability of the wall surface 131a of the heater holder 130 and the side surface 113a of the heater 113, which form the gap 132. In the conventional example, when the base oil Gb initially contacts the gap, as shown in FIG. 8B, the base oil Gb adheres only to a small portion of the wall surface 131a of the heater holder 130 and the side surface 113a of the heater 113. However, as the cumulative usage time of the fixing device 100 increases or as time passes after assembly, the base oil Gb wets the wall surface 131a and the side surface 113a and spreads toward the back of the gap 132 and outward from the initial lubricant application area Lg in the longitudinal direction B.

[0110] When the base oil that has spread in the longitudinal direction B reaches the boundary of the film contact area Lf (the longitudinal end of the fixing film 112), the base oil Gb wraps around the outer surface of the fixing film 112 and flows out (leaks) to the outside. In particular, when the base oil Gb that has wrapped around the outer surface of the fixing film 112 reaches the fixing nip N (nip pressure area Lp), the base oil Gb may be sucked out by capillary action in the gap in the fixing nip N formed between the fixing film 112 and the pressure roller 110. In this situation, the loss of a large amount of base oil Gb increases the sliding friction resistance of the fixing film 112, reduces the conveying force of the recording material in the fixing nip N, contaminates the recording material, and cracks are likely to occur in the release layer of the pressure roller 110 due to swelling caused by the base oil Gb.

[0111] For comparison, Figure 8(c) shows a case where a material (lipophilic agent) exhibiting lipophilicity toward the base oil Gb is applied to both longitudinal ends of the fitting groove 131 of the heater holder 130. The lipophilic agent used here is a silane coupling agent having a fluorinated alkyl group (triethoxy-1H,1H,2H,2H-heptadecafluorodecylsilane, T2876, manufactured by Tokyo Chemical Industry Co., Ltd.). The fluorine oil used as the base oil Gb in this embodiment and the surface treated with the silane coupling agent having a fluorinated alkyl group (lipophilic treated area) have similar contact angles with hexadecane, making them lipophilic and easily wettable. Therefore, in this comparative example, the diffusion of the base oil Gb in the longitudinal direction B through the gaps 132 is promoted, resulting in a larger amount of the base oil Gb leaking (leaking) out of the fixing film 112 in a short period of time.

[0112] On the other hand, in this embodiment, an oil repellent is applied to both longitudinal ends of the fitting groove 131 of the heater holder 130, so that in the initial state when the base oil Gb comes into contact with the gap 132, the state is as shown in FIG. 8(d). As shown in the figure, the oil repellency of the wall surface 131a of the fitting groove 131 to the base oil Gb makes it difficult for capillary action to occur, and the diffusion of the base oil Gb in the longitudinal direction B through the gap 132 is suppressed. As a result, even if the cumulative usage time of the fixing device 100 increases or the time that has passed since assembly increases, the outflow (leakage) of the base oil Gb through the gap 132 due to capillary action is suppressed, and inconveniences caused by the outflow (leakage) of the base oil Gb can be prevented. The oil repellents used were KF-965-1,000cs (Shin-Etsu Chemical Co., Ltd.), DOWSIL SH 200 Fluid 2,000cSt (Dow-Toray), KBE-13 (methyltriethoxysilane), KBE-22 (dimethyldiethoxysilane), KBE-3083 (octyltriethoxysilane), and KBM-13 (methyltrimethoxysilane) (all manufactured by Shin-Etsu Chemical Co., Ltd.).

[0113] (Comparative experiment) A comparative experiment was conducted to confirm the effectiveness of the oil-repellent treatment. A conventional fixing device 100 without an oil-repellent or lipophilic agent applied to the fitting groove 131 of the heater holder 130 and a fixing device 100 with materials having different hexadecane contact angles applied to the fitting groove 131 of the heater holder 130 were prepared. These fixing devices 100 were aged by rotating the pressure roller 110 while heating the heater 113, and then left in a high-temperature environment at 40°C to comparatively observe leakage of base oil from the fixing film 112. After aging, the aged fixing device 100 showed visually increasing leakage of lubricant (particularly base oil) from the edge of the fixing film 112 over time, with the higher the ambient temperature, the more significant the leakage. In Table 4, if there was no leakage of base oil after 48 hours of aging, an O is indicated, and if there was leakage, an X is indicated. The extent of leakage will be discussed later, taking into account the observation results. The materials used as the oil repellent or lipophilic agent and the evaluation results of the durability of the fixing device 100 with respect to leakage of the lubricant are shown in Table 1. 。

[0114] [Table 4]

[0115] In the conventional example, the heater holder 130 is made of a liquid crystal polymer, and the inner surface of the fitting groove 131 is also made of this liquid crystal polymer. In this case, the contact angle γ of hexadecane with the surface of the liquid crystal polymer is 36.2°. On the other hand, the contact angle γ of hexadecane with the surface of the liquid crystal polymer, which is the material of the heater holder 130, coated with base oil Gb, is 61.9°. Therefore, the difference (Δγ) in the contact angle of hexadecane with the base oil on the surface of the heater holder 130 without the application of an oil-repellent or lipophilic agent is 25.7°. In this conventional example, leakage of the base oil Gb was confirmed.

[0116] In a comparative example in which a silane coupling agent T2876 having a fluoroalkyl group exhibiting lipophilicity toward the base oil was applied, the hexadecane contact angle γ on the surface of the heater holder 130 was 63.0°, and the difference in the contact angle of hexadecane with the base oil (Δγ) was 1.1°. In this comparative example, the leakage of the base oil Gb was more pronounced than in the conventional example. This indicates that the lipophilicity of the surface of the engagement groove 131 toward the base oil Gb promotes the movement of the base oil Gb in the longitudinal direction B through the gap 132 due to capillary action, making it easier for the base oil Gb to reach the edge of the fixing film 112.

[0117] In contrast, when silicone oil (oil repellents 1 and 2) according to the present embodiment was applied, the difference in contact angle (Δγ) between the base oil and hexadecane was 41.3° or 41.8°, which was larger than the Δγ of the conventional examples. In these examples, no leakage of the base oil Gb was observed, and it can be said that the durability of the fixing device 100 with respect to leakage of the base oil Gb was significantly improved. Furthermore, when the silane coupling agents shown in oil repellents 3 to 6 were applied and baked, the difference in contact angle (Δγ) between the base oil and hexadecane was 35.0° to 38.1°, which was larger than the Δγ of the conventional examples. In these examples, no leakage of the base oil Gb was observed.

[0118] However, when the heater holder 130 was treated with oil repellent agent 7 (silane coupling agent KBE-903), the difference in the contact angle (Δγ) between the base oil and hexadecane was 27.0°, which was only a slight increase compared to the conventional example (25.7°). When oil repellent agent 7 was used, the leakage of the base oil was slightly improved compared to the conventional example, but not significantly.

[0119] As the above results show, applying an oil repellent agent that is oil repellent to the base oil Gb to the longitudinal ends of the fitting groove 131 of the heater holder 130 can prevent the base oil Gb from leaking out of the lubrication target area due to capillary action. In particular, it can prevent the base oil Gb from leaking out of the fixing film 112 through the ends of the fixing film 112. This prevents problems associated with base oil Gb leakage, such as contamination of the recording material and poor conveyance, swelling and cracking of the release layer of the pressure roller, and depletion of base oil in the lubrication target area, and can maintain the performance of the fixing device 100 over a long period of time. Furthermore, the results of comparative experiments show that a material with a large difference in contact angle (Δγ) between the base oil Gb and hexadecane is preferable for the oil repellent agent applied to the fitting groove 131. Specifically, an oil repellent agent with a Δγ of 35.0° or greater is preferable.

[0120] Sixth Embodiment A sixth embodiment of the present disclosure will be described below. The sixth embodiment differs from the fifth embodiment in the range to which the oil repellent is applied. Hereinafter, elements with the same reference symbols as the fifth embodiment will be considered to have substantially the same configurations and functions as those described in the fifth embodiment, and elements that differ from the fifth embodiment will be mainly described.

[0121] 9(a) and 9(b) show the application areas of the oil repellent in this embodiment. In the fifth embodiment, the oil repellent is applied to the longitudinal ends (particularly both ends) of the inner surface of the fitting groove 131 of the heater holder 130. FIG. 9(a) is a cross-sectional view of the heater holder 130 and its periphery taken along a plane perpendicular to the longitudinal direction B. FIG. 9(b) is a view of the heater holder 130 from which the heater 113 has been removed, viewed from the fixing nip N side in the vertical direction C, showing the oil repellent treated area AP to which the oil repellent is applied. In this embodiment, as shown in FIG. 9(a), in addition to the inner surface of the fitting groove 131, an oil repellent that is oil repellent to the base oil Gb is also applied to both longitudinal ends of the film contact surface 133 (guide surface, sliding surface) where the heater holder 130 comes into contact with the inner surface of the fixing film 112. That is, the oil repellent treatment portion AP in this embodiment includes the inner surface of the fitting groove 131 in the heater holder 130 and portions extending upstream and downstream of the fitting groove 131 in the recording material conveying direction A.

[0122] In the fifth embodiment, the leakage of the base oil Gb to the outside of the fixing film 112 due to capillary action is prevented by applying an oil repellent to both longitudinal ends of the fitting groove 131 of the heater holder 130, but there are other paths for the base oil Gb to leak to the outside of the fixing film 112 besides the fitting groove 131. According to this embodiment, it is possible to suppress the leakage of the base oil Gb due to capillary action in the gap between the heater 113 and the fitting groove 131 of the heater holder 130, as well as the leakage of the base oil Gb due to capillary action in the gap between the fixing film 112 and the film contact surface 133 of the heater holder 130. This makes it possible to more effectively suppress the occurrence of inconveniences caused by the outflow (leakage) of the base oil Gb to the outside of the fixing film 112.

[0123] Seventh Embodiment A seventh embodiment of the present disclosure will be described below. The seventh embodiment differs from the fifth embodiment in the range to which the oil repellent is applied. Hereinafter, elements with the same reference symbols as the fifth embodiment will be considered to have substantially the same configurations and functions as those described in the fifth embodiment, and elements that differ from the fifth embodiment will be mainly described.

[0124] 10(a) and 10(b) show the application area of ​​the oil repellent in this embodiment. In the fifth embodiment, the oil repellent was applied to the inner surface of the fitting groove 131 of the heater holder 130, but in this embodiment, as shown in FIGS. 10(a) and 10(b), the oil repellent is applied not only to the inner surface of the fitting groove 131 but also to the sliding surface 113S and side surface 113a of the heater 113. In other words, the oil repellent treatment portion AP, which is the oil repellent portion in this embodiment, includes the longitudinal ends of the fitting groove 131 and the longitudinal ends of the heater 113.

[0125] In this embodiment, the oil repellent is applied not only to the fitting groove 131 of the heater holder 130 but also to the longitudinal ends of the heater 113, making it even less likely that capillary action will occur through the gap 132 compared to the fifth embodiment (FIG. 8(d)). This inhibits the base oil Gb from diffusing in the longitudinal direction B through the gap 132, further suppressing leakage of the base oil Gb to the outside of the fixing film 112. This more effectively suppresses problems caused by the base oil Gb leaking out of the fixing film 112. Note that even if the oil repellent is not applied to the fitting groove 131 but is applied only to the longitudinal ends of the heater 113, it is still possible to suppress leakage of the base oil Gb to the outside of the fixing film 112, although this may be less effective than the present embodiment.

[0126] Eighth Embodiment An eighth embodiment of the present disclosure will be described below. The eighth embodiment differs from the fifth embodiment in the range to which the oil repellent is applied. Hereinafter, elements with the same reference symbols as the fifth embodiment will be considered to have substantially the same configurations and functions as those described in the fifth embodiment, and elements that differ from the fifth embodiment will be mainly described.

[0127] 11 shows the application area of ​​the oil repellent in this embodiment. In the fifth embodiment, the oil repellent was applied to the inner surface of the fitting groove 131 of the heater holder 130, but in this embodiment, the oil repellent is applied to the fixing flange 120 in addition to the inner surface of the fitting groove 131. The fixing flange 120 has an arc-shaped (crescent-shaped) inner surface guide portion 120a as a sliding portion that slides against the inner surface of the fixing film 112, and a flange-shaped end surface guide portion 120b that faces the longitudinal end of the fixing film 112. The oil repellent that is oil repellent to the base oil Gb is applied to at least the inner surface guide portion 120a of the fixing flange 120. In other words, the oil repellent treatment portion AP, which is the oil repellent portion in this embodiment, includes the longitudinal end of the fitting groove 131 and the inner surface guide portion 120a, which is the sliding portion of the fixing flange 120.

[0128] In the fifth embodiment, the leakage of the base oil Gb to the outside of the fixing film 112 due to capillary action was prevented by applying an oil repellent to both longitudinal ends of the fitting groove 131 of the heater holder 130, but there are other paths for the base oil Gb to leak to the outside of the fixing film 112 besides the fitting groove 131. According to this embodiment, it is possible to suppress the leakage of the base oil Gb due to capillary action in the gap between the heater 113 and the fitting groove 131 of the heater holder 130, as well as the capillary action in the gap between the fixing film 112 and the fixing flange 120. This makes it possible to more effectively suppress the occurrence of problems caused by the leakage (leakage) of the base oil Gb to the outside of the fixing film 112. Note that even if the oil repellent is not applied to the fitting groove 131 and is applied only to the fixing flange 120, the leakage (leakage) of the base oil Gb to the outside of the fixing film 112 can be suppressed, although the effect may be less than in this embodiment.

[0129] Ninth Embodiment A ninth embodiment of the present disclosure will be described below. The ninth embodiment differs from the fifth embodiment in the range to which the oil repellent is applied. Hereinafter, elements with the same reference symbols as the fifth embodiment will be considered to have substantially the same configurations and functions as those described in the fifth embodiment, and elements that differ from the fifth embodiment will be mainly described.

[0130] 12 shows the application area of ​​the lube repellent in this embodiment. In the fifth embodiment, the lube repellent was applied to the inner surface of the fitting groove 131 of the heater holder 130, but in this embodiment, the lube repellent is applied to the inner surface of the fixing film 112 in addition to the inner surface of the fitting groove 131. Specifically, an lube repellent that is oil-repellent to the base oil Gb is applied to the inner surface of the fixing film 112, at the outer end (particularly both ends) of the lubricant application area Lg in the longitudinal direction B. In other words, the oil repellent treatment area AP, which is the oil repellent portion in this embodiment, includes the wall surface 131a and bottom surface 131b of the fitting groove 131 (see FIG. 7(a)) and both longitudinal end portions of the inner surface of the fixing film 112.

[0131] According to this embodiment, leakage of the base oil Gb due to capillary action in the gap between the heater 113 and the fitting groove 131 of the heater holder 130, as well as due to capillary action in the gap between the inner surface of the fixing film 112 and another member that slides against the inner surface of the fixing film 112, can be suppressed. The other member that slides against the inner surface of the fixing film 112 is, for example, the heater holder 130 or the fixing flange 120, but may be another member depending on the specific configuration of the fixing device. This more effectively suppresses the occurrence of problems caused by the base oil Gb leaking out of the fixing film 112. Note that even if the oil repellent is not applied to the fitting groove 131 but is applied only to the longitudinal end portions of the inner surface of the fixing film 112, the leakage of the base oil Gb out of the fixing film 112 can still be suppressed, although the effect may be less than that of this embodiment.

[0132] Tenth Embodiment A tenth embodiment of the present disclosure will be described below. The tenth embodiment differs from the fifth embodiment in the range to which the oil repellent is applied. Hereinafter, elements with the same reference symbols as the fifth embodiment will be considered to have substantially the same configurations and functions as those described in the fifth embodiment, and elements that differ from the fifth embodiment will be mainly described.

[0133] 13 shows the application area of ​​the oil repellent in this embodiment. In the fifth embodiment, the oil repellent was applied to the inner surface of the fitting groove 131 of the heater holder 130, but in this embodiment, the oil repellent is applied not only to the inner surface of the fitting groove 131 but also to the outer surface of the fixing film 112. Specifically, an oil repellent that is oil repellent to the base oil Gb is applied to both ends of the inner surface of the outer surface of the fixing film 112 in the longitudinal direction B. In other words, the oil repellent treatment portion AP, which is the oil repellent portion in this embodiment, includes the wall surface 131a and bottom surface 131b of the fitting groove 131 (see FIG. 7(a)) and both ends of the outer surface of the fixing film 112 in the longitudinal direction.

[0134] The oil-repellent treated portion AP on the outer surface of the fixing film 112 is preferably provided outside the maximum recording material width W (maximum paper passing area) in the fixing nip N in the longitudinal direction B. The maximum recording material width W refers to the range in the longitudinal direction B through which the recording material passes when it passes through the fixing nip N, among the recording materials that can be fixed by the fixing device (recording materials on which the image forming device can form an image).

[0135] In this embodiment, a conductive portion E, where the conductive base layer is exposed, is provided at an end of the fixing film 112 in the longitudinal direction B, and the oil-repellent treatment portion AP is the area excluding the conductive portion E. By connecting a voltage application circuit to the conductive portion E and applying a predetermined bias voltage to the base layer, the occurrence of electrostatic offset and tailing in the fixing nip N can be suppressed. Electrostatic offset occurs when the electrical resistance of the recording material decreases due to moisture absorption in high humidity, reducing the electrostatic retention force of the unfixed toner image on the recording material. This causes the toner image to transfer to the fixing film 112 as it passes through the fixing nip and then re-adhere to the recording material, resulting in an unwanted image. Tailing is an image defect in which water vapor generated during the fixing of a moisture-absorbed recording material causes a stretching (tailing) of a horizontal line image in the recording material conveyance direction (i.e., a trailing image). Applying a bias voltage of the same polarity as the normal charging polarity of the toner to the base layer of the fixing film 112 constrains the unfixed toner image to the recording material surface, suppressing the occurrence of these image defects. The conductive portion E is excluded from the oil repellent treatment portion AP in order to prevent the conductivity of the conductive portion E from being lost due to application of the oil repellent agent.

[0136] According to this embodiment, not only is it possible to prevent the base oil Gb from leaking out of the fixing film due to capillary action, but it is also possible to prevent the base oil Gb that has reached the outer surface of the fixing film 112 from reaching the gap (fixing nip N) between the fixing film 112 and the pressure roller 110. This makes it possible to more effectively prevent problems such as a decrease in the conveyance performance of the recording material, contamination of the recording material, and swelling and cracking of the release layer of the pressure roller 110, which are caused by the base oil Gb that has reached the outer surface of the fixing film 112 leaking out through the fixing nip N. Note that even if the oil repellent is not applied to the engagement groove 131 and is applied only to the longitudinal end portions of the outer surface of the fixing film 112, it is possible to prevent the base oil Gb from reaching the fixing nip N, although this may be less effective than in this embodiment.

[0137] Eleventh Embodiment An eleventh embodiment of the present disclosure will be described below. The eleventh embodiment differs from the fifth embodiment in the range to which the oil repellent is applied. Hereinafter, elements with the same reference symbols as the fifth embodiment will be considered to have substantially the same configurations and functions as those described in the fifth embodiment, and elements that differ from the fifth embodiment will be mainly described.

[0138] 14 shows the application area of ​​the oil repellent in this embodiment. In the fifth embodiment, the oil repellent was applied to the inner surface of the fitting groove 131 of the heater holder 130. However, in this embodiment, the oil repellent is applied not only to the inner surface of the fitting groove 131 but also to the surface of the pressure roller 110. Specifically, an oil repellent that is oil repellent to the base oil Gb is applied to the longitudinal ends (particularly both ends) of the outer peripheral surface of the pressure roller 110 (the surface that comes into contact with the fixing film 112 in the fixing nip N). That is, the oil repellent treatment area AP, which is the oil repellent area in this embodiment, includes the wall surface 131a and bottom surface 131b of the fitting groove 131 (see FIG. 7A) and both longitudinal ends of the outer peripheral surface of the pressure roller 110. The oil repellent treatment area AP on the outer peripheral surface of the pressure roller 110 is preferably provided outside the maximum recording material width W (maximum paper passing area) in the fixing nip N in the longitudinal direction B.

[0139] According to this embodiment, not only is it possible to prevent the base oil Gb from leaking out of the fixing film due to capillary action, but it is also possible to prevent the base oil Gb that has reached the outer surface of the fixing film 112 from reaching the gap (fixing nip N) between the fixing film 112 and the pressure roller 110. This makes it possible to more effectively prevent problems such as a decrease in the conveyance performance of the recording material, contamination of the recording material, and swelling and cracking of the release layer of the pressure roller 110, which are caused by the base oil Gb that has reached the outer surface of the fixing film 112 leaking out through the fixing nip N. Note that even if the oil repellent is not applied to the engagement groove 131 and is applied only to the longitudinal ends of the pressure roller 110, it is possible to prevent the base oil Gb from reaching the fixing nip N, although this may be less effective than in this embodiment.

[0140] Also, when a pressure member other than a pressure roller (for example, the above-mentioned belt unit) is used, the oil repellent may be applied to the longitudinal end of the outer circumferential surface of the rotating member that comes into contact with the fixing film 112 in the fixing nip N.

[0141] <Twelfth embodiment> A twelfth embodiment of the present disclosure will be described below. In the twelfth embodiment, the components of the base oil Gb are different from those in the fifth embodiment, and the oil repellent is also changed accordingly. Hereinafter, elements with the same reference symbols as those in the fifth embodiment will be considered to have substantially the same configurations and functions as those described in the fifth embodiment, and elements different from those in the fifth embodiment will be mainly described.

[0142] In the fifth to eleventh embodiments, a fluorine oil is used as the base oil Gb of the lubricant G. Fluorine oil has the advantage of providing high sliding properties and durability in high-temperature environments, but silicone oil may be used as the base oil Gb depending on the temperature range used and various conditions. Even when silicone oil is used as the base oil Gb, various inconveniences may occur if the base oil Gb leaks out of the fixing film 112 due to capillary action in the gap 132 between the heater holder 130 and the heater 113. Therefore, when silicone oil is used as the base oil Gb, it is effective from the viewpoint of improving the durability of the fixing device to apply an oil-repellent treatment to both longitudinal ends of the fitting groove 131 of the heater holder 130, etc., to increase the oil-repellent properties against silicone oil.

[0143] As the oil repellent of this embodiment, a fluorine oil such as perfluoropolyether or a silane coupling agent having a fluorinated functional group can be used. Coupling agents that can be used as the oil repellent of this embodiment are those represented by the above general formula (C). Examples of silane coupling agents represented by general formula (C) include trifluoropropyltrimethoxysilane.

[0144] Table 5 shows the results of observing the hexadecane contact angle when silicone oil, which is the base oil Gb in this embodiment, and each material used as an oil repellent or lipophilic agent is applied to the heater holder 130, and the presence or absence of leakage of the base oil Gb after aging. The details of the experimental method are the same as those explained in Table 4. Oil repellent 1, Fomblin M30, was applied to both longitudinal ends of the fitting groove 131 of the heater holder 130, and the silane coupling agents of oil repellents 2 and 3 and lipophilic agents 1 to 4 were applied to both longitudinal ends of the fitting groove 131 of the heater holder 130 and baked.

[0145] [Table 5]

[0146] As shown in Table 5, the contact angle γ of hexadecane on the surface of the liquid crystal polymer (conventional example) without any application of an oil-repellent or lipophilic agent is 36.2°. On the other hand, the contact angle γ of hexadecane on the surface of the liquid crystal polymer, the material of the heater holder 130, coated with silicone oil, which is the base oil Gb of this embodiment, is 20.6°. Therefore, the difference (Δγ) in the contact angle of hexadecane on the surface of the heater holder 130 without any application of an oil-repellent or lipophilic agent with respect to the base oil Gb is 15.6°. In this conventional example, leakage of the base oil Gb from the edge of the fixing film 112 was confirmed after aging.

[0147] When a silane coupling agent (lipophilic agents 1 to 4) exhibiting lipophilicity to the base oil Gb was applied to the fitting groove 131 of the heater holder 130, the hexadecane contact angle γ on the surface of the heater holder 130 was 25.7° to 34.9°. Therefore, the difference (Δγ) in the contact angle of hexadecane with respect to the base oil Gb in this embodiment was 5.1° to 14.3°, which was smaller than the Δγ of the conventional example. In these examples, leakage of the base oil Gb from the end of the fixing film 112 after aging was confirmed. This indicates that the lipophilic agent promoted the longitudinal diffusion of the base oil Gb through the gap 132 between the heater holder 130 and the heater 113.

[0148] When oil repellents 1 to 3, which are oil repellent to the base oil Gb of this embodiment, were used, the difference (Δγ) in the contact angle of hexadecane with respect to the base oil Gb was 39.0° to 42.4°, which was larger than Δγ in the conventional example. In these examples, no leakage of the base oil Gb was observed, and it can be said that the base oil Gb was less likely to flow (leak) out of the fixing film 112 than in the conventional example, and the durability of the fixing device was improved.

[0149] As the above results show, even if the components of the base oil Gb are different from those in the fifth embodiment, by applying an oil repellent that is oil repellent to the base oil Gb to both longitudinal ends of the fitting groove 131 of the heater holder 130, it is possible to prevent the base oil Gb from leaking out of the fixing film 112. This makes it possible to maintain the performance of the fixing device 100 over a long period of time. Furthermore, according to the results in Table 5, it is preferable that the oil repellent applied to the fitting groove 131 be one that results in a difference (Δγ) in the contact angle of hexadecane with respect to the base oil Gb of 35.0° or more.

[0150] <Thirteenth embodiment> A thirteenth embodiment of the present disclosure will be described. In this embodiment, a basic configuration of a fixing device that is different from the fifth to twelfth embodiments will be described. Hereinafter, elements that are given the same reference symbols as those in the fifth embodiment have substantially the same configurations and functions as those described in the fifth embodiment, and elements that are different from the fifth embodiment will be mainly described.

[0151] The fixing device in this embodiment is the same as that described in the fourth embodiment (see FIGS. 6(a) and 6(b)). That is, the fixing device in this embodiment includes a sliding plate that slides on the inner surface of the film-like member (belt-like member) in the fixing device, and a sliding plate holding member that has a fitting groove into which the sliding plate fits.

[0152] In this configuration, if the base oil of the lubricant diffuses in the longitudinal direction B due to capillary action through the gap between the sliding plate and the fitting groove of the sliding plate holding member that holds the sliding plate and leaks out of the film-shaped member, various inconveniences described in the fifth embodiment may occur. Therefore, with reference to the fifth to twelfth embodiments, an oil-repellent treatment is applied to the longitudinal ends (preferably both ends) of the fitting groove of the sliding plate holding member, the film sliding surface of the sliding plate holding member, the side surface of the sliding plate, the flange member that guides the film-shaped member, the inner or outer surface of the film-shaped member, and / or the roller member facing the film-shaped member by applying an oil-repellent agent that repels the base oil. This makes it possible to prevent the base oil from leaking out of the film-shaped member due to capillary action. Therefore, as in the fifth to twelfth embodiments, it is possible to suppress inconveniences such as a decrease in the conveying force of the recording material due to leakage of base oil, contamination of the recording material, and cracking due to the release layer of the pressure roller 110 swelling with base oil Gb, thereby improving the durability of the fixing device.

[0153] (Other embodiments) In the first to fourth embodiments, the heater holder's fitting groove and other components are treated with an oil-repellent coating to prevent base oil depletion due to capillary action in the gap between the heater (sliding plate) and the heater holder (sliding plate holding member). Meanwhile, the fifth to thirteenth embodiments are treated with an oil-repellent coating on the longitudinal ends of the heater holder's fitting groove and other components to prevent base oil from leaking out of the fixing film (outside the film-like member) due to capillary action. The oil-repellent coatings described in the first to fourth embodiments and the fifth to thirteenth embodiments can be simultaneously applied to a single fixing device. This can more effectively prevent base oil depletion and leakage out of the fixing film. As an example, an oil-repellent agent can be applied to the entire longitudinal area of ​​the heater holder's fitting groove, as well as to the longitudinal ends of the heater holder surface other than the fitting groove or other components (such as a fixing flange). [Explanation of symbols]

[0154] 100... fixing device / 110... pressure member (pressure roller) / 112... film (fixing film) / 113... heater / 130... heater holder / 131... fitting groove / AP... oil-repellent portion (oil-repellent treated portion) / G... lubricant / Gb... base oil

Claims

1. a rotatable endless film; a heater that slides on the inner surface of the film via a lubricant; a heater holder that holds the heater; a pressure member that is in pressure contact with the heater via the film and forms a nip portion between the pressure member and the heater; a fixing device that fixes a toner image formed on a recording material by using the film heated by the heater while conveying the recording material while sandwiching the recording material between the film and the pressure member at the nip portion, The lubricant comprises a base oil and a thickener; the heater holder has a fitting groove into which the heater is fitted, A fixing device characterized in that the engagement groove is provided with an oil-repellent portion that is oil-repellent to the base oil within the range in which the heater slides on the inner surface of the film in the longitudinal direction of the nip portion.

2. a rotatable endless film; a heater that slides on the inner surface of the film via a lubricant; a heater holder that holds the heater; a pressure member that is in pressure contact with the heater via the film and forms a nip portion between the pressure member and the heater; a fixing device that fixes a toner image formed on a recording material by using the film heated by the heater while conveying the recording material while sandwiching the recording material between the film and the pressure member at the nip portion, The lubricant comprises a base oil and a thickener; the heater holder has a fitting groove into which the heater is fitted, a fixing device characterized in that an oil-repellent portion that is oil-repellent to the base oil is provided on the surface of the heater that faces the wall surface of the fitting groove, within a range in which the heater slides on the inner surface of the film in the longitudinal direction of the nip portion.

3. 2. The fixing device according to claim 1, wherein an oil-repellent portion exhibiting oil repellency to the base oil is provided on the surface of the heater facing the wall surface of the engagement groove within a range in which the heater slides against the inner surface of the film in the longitudinal direction.

4. a rotatable endless film; a sliding member that slides on the inner surface of the film via a lubricant; a holding member that holds the sliding member; a pressure member that is in pressure contact with the sliding member via the film and forms a nip portion between the pressure member and the sliding member; a heating means for heating the nip portion; a fixing device for fixing a toner image formed on a recording material by using the film heated by the heating means while conveying the recording material while sandwiching the recording material between the film and the pressure member at the nip portion, The lubricant comprises a base oil and a thickener; the holding member has a fitting groove into which the sliding member is fitted, a fixing device characterized in that the engagement groove is provided with an oil-repellent portion that is oil-repellent to the base oil within a range in which the sliding member slides on the inner surface of the film in the longitudinal direction of the nip portion.

5. 5. The fixing device according to claim 1, wherein the oil repellent portion is provided over the entire area of ​​the fitting groove in the longitudinal direction.

6. a rotatable endless film; a heater that slides on the inner surface of the film via a lubricant; a heater holder that holds the heater; a pressure member that is in pressure contact with the heater via the film and forms a nip portion between the pressure member and the heater; a fixing device that fixes a toner image formed on a recording material by using the film heated by the heater while conveying the recording material while sandwiching the recording material between the film and the pressure member at the nip portion, The lubricant comprises a base oil and a thickener; the heater holder has a fitting groove into which the heater is fitted, The fixing device is characterized in that an oil-repellent portion that is oil-repellent to the base oil is provided at an end of the engagement groove in the longitudinal direction of the nip portion.

7. the heater holder has a sliding surface that slides on the inner surface of the film via the lubricant, 7. The fixing device according to claim 1, wherein an oil-repellent portion that is oil-repellent to the base oil is provided at an end of the sliding surface in the longitudinal direction.

8. The film further includes a flange member for guiding the rotational path of the film; the flange member has a sliding surface that slides on an inner surface of an end portion of the film in the longitudinal direction via the lubricant, 8. The fixing device according to claim 1, wherein an oil-repellent portion that is oil-repellent to the base oil is provided on the sliding surface of the flange member.

9. 7. The fixing device according to claim 1, wherein the oil-repellent portion is a region coated with an oil-repellent agent that is repellent to the base oil.

10. 10. The fixing device according to claim 9, wherein the difference between the contact angle of hexadecane with the surface on which the base oil is applied and the contact angle of hexadecane with the surface on which the oil repellent is applied is 35.0° or more.

11. The main component of the base oil is perfluoropolyether, 11. The fixing device according to claim 9, wherein the main component of the oil repellent is silicone oil.

12. 12. The fixing device according to claim 11, wherein the silicone oil is dimethylpolysiloxane.

13. The main component of the base oil is perfluoropolyether, 11. The fixing device according to claim 9, wherein the main component of the oil repellent is a silane coupling agent represented by the following general formula (1): Rm-Si-Yn (1) (In the formula, R represents an alkoxy group, m represents an integer of 1 to 3, Y represents an organic functional group not containing a fluoro group, and n represents an integer of 1 to 3, provided that m+n=4.)

14. The fixing device according to claim 13, wherein the silane coupling agent is an alkyltrialkoxysilane coupling agent.

15. The main component of the base oil is silicone oil, 11. The fixing device according to claim 9, wherein the main component of the oil repellent is perfluoropolyether.

16. The main component of the base oil is silicone oil, 11. The fixing device according to claim 9, wherein the main component of the oil repellent is a silane coupling agent represented by the following general formula (2): Rm-Si-Yn (2) (In the formula, R represents an alkoxy group, m represents an integer of 1 to 3, Y represents an organic functional group containing a fluoro group, and n represents an integer of 1 to 3, provided that m+n=4.)

17. a toner image forming means for forming a toner image on a recording material; a fixing device according to claim 1 , which fixes the toner image formed on the recording material to the recording material; An image forming apparatus comprising:

Images