Fixing belt and fixing device

Abstract

When a lubricant leaking from an end of a fixing belt adheres to an exposed elastic layer at the end of the belt, the lubricant will penetrate into the elastic layer and cause the elastic layer to swell, which may lead to damage from continuous use.　Provided is a fixing belt. The fixing belt has a total length W, and an elastic layer is exposed on at least one end surface of the fixing belt in the longitudinal direction. When a central region B is a region extending from the center of the fixing belt in the longitudinal direction to both ends up to W / 3, an end region A is a region closer to an end than the central region B, an end region A1 is a region of the end region A including the end surface in which the elastic layer is exposed, and QB[%] is the degree of swelling when the elastic layer in the central region B is immersed at a temperature of 25°C for 12 hours in a dimethyl silicone oil having a kinematic viscosity of 10 m2 / s at a temperature of 200°C, a region C exhibiting the degree of swelling QC [%] satisfying QC<QB is present, in the end region A1, in a width of 1 mm or more with respect to the longitudinal direction.

Description

Fixing belt and fixing device

[0001] The present disclosure relates to a fixing belt used in a fixing device of an electrophotographic image forming apparatus, and to the fixing device.

[0002] An electrophotographic image forming apparatus is equipped with a fixing device that fixes a toner image formed on a recording material (hereinafter also referred to as "paper") by applying heat and pressure to the paper. This fixing device is equipped with fixing members such as a heating belt (heating roller) and a pressure roller (pressure belt), and is configured to perform fixing processing at a position where these are in pressure contact with each other (fixing nip portion).

[0003] One example of a fixing device is a belt (film) heating type device. This device has a heater as a heating element (heat source). It also has an endless fixing belt that contains the heater and rotates as a heating element. It also has a pressure roller (pressure rotating body) that presses against the fixing belt to form a fixing nip and drives the fixing belt to rotate as a fixing nip forming member. This belt heating type allows for a low thermal capacity and compact size of the fixing belt, thereby saving energy in the fixing device and shortening the time (warm-up time) required for the fixing belt to reach a predetermined temperature sufficient to heat and fix a toner image.

[0004] The fixing belt substrate is made of a heat-resistant resin material such as polyimide, or a metal material such as electroformed nickel or SUS, etc. An elastic layer made of heat-resistant rubber such as silicone rubber is provided on the fixing belt or roller-shaped substrate.

[0005] By providing an elastic layer, when a recording material such as paper with toner transferred thereon passes through the fixing nip formed by two opposing fixing members, i.e., a heating member and a pressure member, the flexibility of the elastic layer rubber allows the surface of the fixing member to deform in accordance with the toner image on the recording material, increasing the contact area and reducing contact thermal resistance. This allows the toner to be uniformly melted and fixed on the recording material, resulting in a high-quality image with no uneven fixing and high gloss.

[0006] In such a fixing device, a lubricant such as heat-resistant sliding grease or oil is applied between the inner surface of the fixing belt and the member that rubs against the inner surface of the fixing belt to maintain the sliding properties of the fixing belt. In such a system, the lubricant leaks from the end of the fixing belt after long-term use, adheres to and is absorbed by the elastic layer, and the elastic layer swells, reducing its strength and causing the fixing belt to break.

[0007] In Patent Document 1, the problem of lubricant leaking from the end of the fixing belt is addressed by providing grooves on the outer peripheral surface of the fixing belt guide member and the inner peripheral surface of the fixing belt to prevent leakage.

[0008] Japanese Patent Application Laid-Open No. 2020-197701

[0009] Incidentally, when grooves are provided on the outer peripheral surface of the fixing belt guide member or on the inner surface of the fixing belt as described in Patent Document 1, it is possible to prevent a small amount of lubricant from leaking out from the belt edge. However, when used for a long period of time or when a large amount of lubricant is used, the lubricant cannot be completely blocked by the grooves and leaks out from the belt edge, and the lubricant penetrates into the elastic layer from the edge, so it can be said that this measure is insufficient.

[0010] The present disclosure is directed to providing a fixing belt that can maintain its strength by preventing the lubricant from penetrating into the elastic layer even if the lubricant leaking from the end of the fixing belt adheres to the exposed elastic layer at the end of the fixing belt, and by preventing the elastic layer from swelling.

[0011] The present disclosure provides a fixing belt having a total length in the longitudinal direction of W, the fixing belt having a base layer, an elastic layer, and a surface layer, the elastic layer being exposed on at least one end surface in the longitudinal direction of the fixing belt, a region extending from the center of the fixing belt to W / 3 toward each end in the longitudinal direction of the fixing belt being defined as a central region B, a region closer to the end than the central region B being defined as an end region A, a region of the end region A including the end surface where the elastic layer is exposed being defined as an end region A1, the elastic layer in the central region B being formed of a material having a kinematic viscosity of 10 m / s at a temperature of 200°C, ２When the degree of swelling when the fixing belt is immersed in dimethyl silicone oil having a kinematic viscosity of 10 m / s at a temperature of 25° C. for 12 hours is QB [%], the end region A1 has a region C having a width of 1 mm or more in the longitudinal direction, the region C exhibiting a degree of swelling QC [%] that satisfies the following formula 1: QC<QB (Formula 1) [where QC is the degree of swelling when the elastic layer in the region C is immersed in dimethyl silicone oil having a kinematic viscosity of 10 m / s at a temperature of 200° C.] ２ / s at a temperature of 25°C for 12 hours.]

[0012] The present disclosure also provides a fixing device including a fixing belt, a pressing member disposed on the inner peripheral surface of the fixing belt and having a rubbing surface that contacts the inner peripheral surface of the fixing belt via grease containing silicone oil, and a pressure member that forms a fixing nip portion between the fixing belt and the pressing member.

[0013] According to the present disclosure, even if the fixing device is used for a long period of time and lubricant leaks from the belt end, it is possible to prevent the belt from being damaged.

[0014] 1 is a schematic diagram of a fixing device in the present embodiment; FIG. 2 is a schematic diagram of a fixing device in the present embodiment; FIG. 3 is a schematic diagram of a fixing device in the present embodiment; FIG. 4 is a cross-sectional view of a fixing belt in the present embodiment; FIG. 5 is a diagram of an elastic layer in which silicone oil is applied to a surface of the elastic layer that is not irradiated with UV light; FIG. 6 is a diagram of an elastic layer in which silicone oil is applied to a surface of the elastic layer that is not irradiated with UV light and then left to stand; FIG. 7 is a diagram of an elastic layer in which silicone oil is applied to a surface of the elastic layer that has been irradiated with UV light and then left to stand; FIG. 8 is a diagram of procedure 1 of a peeling test (including indications of longitudinal lengths W and W / 3, end region A, region C, and end region B); FIG. 9 is a diagram of procedure 2 of a peeling test; FIG. 10 is a schematic diagram of an image forming apparatus in the embodiment;

[0015] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings, but the scope of the present disclosure is not limited to this embodiment, and modifications that do not detract from the spirit of the present disclosure are also included in the present disclosure.

[0016] [Fixing Device] There are several types of fixing devices in this embodiment, and any one of them may be used.

[0017] One of the fixing devices of this embodiment will be described with reference to Fig. 1. The fixing device 100 of this embodiment employs a fixing method using a halogen heater 103 as a heat source. That is, the fixing device 100 includes a cylindrical fixing belt 101, the halogen heater 103 as a heat generating element, a belt guide / pressure member 102 as a rubbing member, and a pressure roller 105 that forms a fixing nip 106 between the fixing belt 101 and the pressure roller 105.

[0018] The halogen heater 103 is fixedly supported on a side plate of the fixing device 100, and is energized by a means (not shown) to generate heat and be controlled to a predetermined set temperature. As a heat source for heating the fixing belt 101, a resistance heating element, a carbon heater, or the like may be used in addition to the halogen heater.

[0019] The fixing belt 101 is an endless belt having a cylindrical polyimide resin base, the inner peripheral surface of which is rubbed against the belt guide / pressure member 102 during use, and which is rotated in accordance with the rotation of the pressure roller 105 .

[0020] Both ends of the fixing belt 101 in the direction of the rotation axis are rotatably supported by fixed portions (not shown) such as a frame of the fixing device 100. Furthermore, a reflective member 104 is provided inside the fixing belt 101 to reflect light emitted from the halogen heater 103 back to the fixing belt 101.

[0021] A semi-solid lubricant (grease) or oil consisting of a solid component (thickener) and a base oil component (oil) (not shown) is applied to the inner surface of the fixing belt 101, ensuring the sliding property between the belt guide / pressure member 102 having a sliding surface and the sliding layer on the inner surface of the fixing belt 101.

[0022] The fixing belt 101 is heated to a predetermined temperature required to melt the toner on its surface by a halogen heater 103. This predetermined temperature is detected by a thermistor (108) as a temperature detection means provided in contact with the outer surface of the fixing belt 101, and is adjusted by controlling the power supply to the halogen heater 103 with a controller (not shown). This thermistor may be provided on the inner surface of the fixing belt 101.

[0023] The pressure roller 105, which serves as a pressure member, is composed of a stainless steel core 105a, an elastic layer 105b of silicone rubber, and a surface layer 105c of a fluororesin (PFA) tube for providing releasability. The shaft portions at both ends of the core 105a are rotatably supported by fixed portions (not shown). The pressure roller 105 is connected to a rotation drive device 107 such as a motor, and is driven to rotate during use.

[0024] In this manner, with the outer surface of the fixing belt 101 kept at a predetermined temperature, the recording material P on which an image is formed with unfixed toner is nipped and conveyed through the fixing nip 106. This heats the recording material P in contact with the outer peripheral surface of the fixing belt 101, causing the toner image T on the recording material P to be heated and pressurized, melted, and mixed, and then cooled, thereby fixing the toner image onto the recording material.

[0025] Another fixing device of this embodiment will be described with reference to Fig. 2. The fixing device 200 of this embodiment is an on-demand fixing type that uses a ceramic heater 203 as a surface evaporative heat source. That is, the fixing device 200 includes a cylindrical fixing belt 101, the ceramic heater 203 that is a heat generating element, a rubbing member, and a heating member, a belt guide / heater holder 202 that is a rubbing member, and a pressure roller 105 that forms a fixing nip portion 106 between the fixing belt 101 and the ceramic heater 203.

[0026] The ceramic heater 203 is formed by applying a conductive paste containing a silver-palladium alloy to an aluminum nitride substrate in the form of a uniformly thick film by screen printing, forming a resistance heating element. The ceramic heater 203 is fitted into a groove provided along the longitudinal direction (the width direction perpendicular to the recording material conveyance direction) of the belt guide / heater holder 202 and fixedly supported, and is configured so that the inner peripheral surface of the fixing belt 101 rubs against the back surface of the substrate (the surface opposite to the surface on which the resistance heating element is formed).

[0027] The ceramic heater 203 is energized by means not shown to generate heat and is controlled to a predetermined set temperature.

[0028] The fixing belt 101 is an endless belt having a cylindrical polyimide resin base, and is rotated in accordance with the rotation of the pressure roller 105 while its inner peripheral surface is rubbed against the belt guide / heater holder 202 and the ceramic heater 203 during use. Both ends of the fixing belt 101 in the rotation axis direction are rotatably supported by fixed parts (not shown) such as a frame of the fixing device 200.

[0029] Also, a belt guide / heater holder 202, a ceramic heater 203, and a stay 204 serving as a support member are arranged inside the fixing belt 101. The stay 204 is arranged in the rotation axis direction of the fixing belt 101, and both ends thereof are supported by fixed portions (not shown) such as a frame of the fixing device 200, and the belt guide / heater holder 202 is supported by the stay 204.

[0030] Belt guide / heater holder 202 is molded from a heat-resistant and heat-insulating liquid crystal polymer or the like, and is disposed along stay 204 in the direction of the rotation axis of fixing belt 101. Fixing belt 101 is loosely fitted onto belt guide / heater holder 202, and the rotation of fixing belt 101 is restricted and guided as the inner peripheral surface of fixing belt 101 rubs against the outer peripheral surface of belt guide / heater holder 202, which is formed in a partially cylindrical shape.

[0031] A semi-solid lubricant (grease) (not shown) made of a solid component (thickener) and a base oil component (oil) is applied to the inner peripheral surface of the fixing belt 101, ensuring slidability between the ceramic heater 203 and the sliding layer on the inner peripheral surface of the fixing belt 101. The pressure roller 105 used is, for example, the one described with reference to FIG.

[0032] In addition, both ends of the stay 204 are urged by a spring pressure mechanism (not shown) with a force of 16 kgf at one end and a total pressure of 32 kgf against the pressure roller 105. This causes the lower surface of the ceramic heater 203 to be pressed against the elastic layer of the pressure roller 105 via the fixing belt 101 with a predetermined pressure, forming a fixing nip portion 106 of a predetermined width required for fixing the toner.

[0033] The pressure roller 105 is connected to a rotation drive device (not shown), and the fixing belt 101 rotates following the pressure roller 105, thereby nipping and conveying the recording material in the fixing nip portion 106. The fixing belt 101 is heated by a ceramic heater 203 to a predetermined temperature required to melt the toner on its surface. This predetermined temperature is detected by a thermistor (not shown) as a temperature detection means provided in contact with the inner surface of the fixing belt 101, and is adjusted by controlling the power supply to the ceramic heater 203 with a controller (not shown).

[0034] In this manner, with the surface of the fixing belt 101 kept at a predetermined temperature, the recording material P on which an image is formed with unfixed toner is nipped and conveyed through the fixing nip 106. As a result, the recording material P in contact with the outer peripheral surface of the fixing belt 101 is heated, and the toner image T on the recording material P is heated and pressurized, melted, and mixed, and then cooled, thereby fixing the toner image on the recording material.

[0035] Another fixing device of this embodiment will be described with reference to Fig. 3. The fixing device 300 of this embodiment uses an induction heating (IH) heater as a heat source. That is, the fixing device 300 includes a cylindrical fixing belt 101, an IH heater 303, a belt guide 304 that assists in heat generation, a friction member / pressure member 302, and a pressure roller 105 that forms a fixing nip 106 with the fixing belt 101.

[0036] The IH heater 303 has a coil portion 303a, a coil bobbin 303b that holds the coil portion 303a in a wound state, and an arch core 303c. The IH heater 303 is arranged to cover the outer surface of the fixing belt 101 at a predetermined interval and is supported by a housing. A magnetic field is generated by applying a high-frequency AC voltage to the coil portion 303a. The action of this magnetic field generates eddy currents in a metal base layer 101d (described below) of the fixing belt 101, causing the base layer 101d to heat up and thereby heating the fixing belt 101. The belt guide 304 also generates heat due to the magnetic field generated by the coil portion 303a, thereby assisting in heating the fixing belt 101.

[0037] The fixing belt 101 is an endless belt having a sliding layer made of polyimide resin formed on the inner peripheral surface of a cylindrical metal substrate, and in use, the inner peripheral surface is rubbed against the rubbing member / pressure member 302, and is rotated in accordance with the rotation of the pressure roller 105. Both ends of the fixing belt 101 in the rotation axis direction are rotatably supported by fixed parts (not shown) such as a frame of the fixing device 300.

[0038] A semi-solid lubricant (grease) or oil consisting of a solid component (thickener) and a base oil component (oil) (not shown) is applied to the inner surface of the fixing belt 101, ensuring the sliding properties between the rubbing member / pressure member 302 and the sliding layer on the inner surface of the fixing belt 101.

[0039] The fixing belt 101 is heated by an IH heater 303 to a predetermined temperature required to melt the toner on its surface. This predetermined temperature is detected by a thermistor (not shown) serving as a temperature detection means provided on the inner surface of the fixing belt 101, and is adjusted by controlling the power supply to the IH heater by a controller (not shown). This thermistor may be provided on the outer surface of the fixing belt 101. The pressure roller 105 used may be, for example, the one described with reference to FIG. 1.

[0040] In this manner, with the surface of the fixing belt 101 kept at a predetermined temperature, the recording material P on which an image is formed with unfixed toner is nipped and conveyed through the fixing nip 106. As a result, the recording material P in contact with the outer peripheral surface of the fixing belt 101 is heated, and the toner image T on the recording material P is heated and pressurized, melted and mixed, and then cooled, thereby fixing the toner image on the recording material.

[0041] The fixing belt of the present disclosure is a fixing belt including a base layer having an endless shape, an elastic layer provided on the outer peripheral surface of the base layer, and a surface layer on the outer peripheral surface of the elastic layer.

[0042] The fixing belt 101 in this disclosure is as shown in FIG. 4 . The fixing belt has a base layer 101d, an elastic layer 101c covering the outer surface of the base layer, and a surface layer 101a covering the surface of the elastic layer opposite the side facing the base layer. An adhesive layer 101b is provided on the surface of the elastic layer 101c opposite the side facing the base layer. If the base layer 101d is made of metal, a resin layer 101e may be provided on the inner surface of the base layer, and if induction fixing is performed, a heat-generating layer (not shown) may be provided between the base layer 101d and the elastic layer 101c.

[0043] (1) Base Layer The material of the base layer 101d is not particularly limited, and any known material used as a base layer for a fixing member such as a fixing belt can be used. For example, metals and alloys such as aluminum, iron, stainless steel, and nickel, as well as heat-resistant resins such as polyimide, can be used. The thickness is not particularly limited, but is preferably 20 μm or more and 100 μm or less from the viewpoints of strength, flexibility, and heat capacity.

[0044] The outer surface of the base layer may be subjected to a surface treatment to impart adhesion to the elastic layer, which may include physical treatments such as blasting, lapping, and polishing, and chemical treatments such as oxidation, coupling agent treatment, and primer treatment, either singly or in combination.

[0045] When an elastic layer containing silicone rubber is provided on the outer surface of the base layer, it is preferable to apply a primer treatment to the surface of the base layer to improve the adhesion between the base layer and the elastic layer. Examples of primers used for the primer treatment include paints in which a silane coupling agent, a silicone polymer, a hydrogenated methylsiloxane, an alkoxysilane, a reaction-accelerating catalyst, and a colorant such as red iron oxide are appropriately blended and dispersed in an organic solvent. The primer can be appropriately selected depending on the material of the base layer, the type of elastic layer, or the form of crosslinking reaction. In particular, when the elastic layer contains a large amount of unsaturated aliphatic groups, a primer containing a hydrosilyl group is preferably used to impart adhesion by reaction with the unsaturated aliphatic group. When the elastic layer contains a large amount of hydrosilyl groups, a primer containing an unsaturated aliphatic group is preferably used.

[0046] Other examples of primers include those containing alkoxy groups. Commercially available primers can be used. The primer treatment includes a step of applying the primer to the outer surface of the base layer (the surface to be bonded to the elastic layer) and drying or baking it.

[0047] (2) Elastic Layer The material of the elastic layer 101c is not particularly limited, and any known material used as an elastic layer for a fixing member such as a fixing belt can be used. The elastic layer preferably contains silicone rubber, which has excellent heat resistance. Furthermore, addition-curing liquid silicone rubber is preferably used as the raw material for the silicone rubber.

[0048] The thickness of the elastic layer can be appropriately designed taking into consideration the surface hardness of the fixing belt and the width of the fixing nip portion to be formed. When the fixing belt is fixing belt 101, the thickness of the elastic layer is preferably 100 μm or more and 1000 μm or less. By setting the thickness of the elastic layer in this range, a sufficient width of the fixing nip portion can be ensured when the fixing belt is incorporated into a fixing device.

[0049] The elastic layer may contain a filler. The filler is added to control the thermal conductivity, heat resistance, and elastic modulus. The tensile elastic modulus of this member is 0.5 N / mm as a fixing member. ２ 1.2N / mm or more ２ The following is preferably used: Tensile modulus of elasticity 0.5 N / mm ２ If the elastic layer is less than 1.2 N / mm, the elastic layer becomes too soft and the life of the edge of the paper is shortened. ２ If the thickness exceeds this value, the elastic layer becomes too hard and is unable to follow the irregularities on the recording medium surface when fixing to the recording medium, resulting in a deterioration in image quality.

[0050] Specifically, silicon carbide (SiC), silicon nitride (Si ３ N ４ ), silica (SiO ２ ), boron nitride (BN), aluminum nitride (AlN), alumina (Al ２ O ３ ), iron oxide (Fe ２ O ３), zinc oxide (ZnO), magnesium oxide (MgO), titanium oxide (TiO ２ Examples of suitable fillers include non-conductive fillers such as ethylenediaminetetraacetic acid (ETA) and propylenediaminetetraacetic acid (PEA).

[0051] The material constituting the elastic layer may contain a reaction control agent (repressor) called an inhibitor to control the reaction initiation time. Known reaction control agents such as methylvinyltetrasiloxane, acetylene alcohols, siloxane-modified acetylene alcohols, and hydroperoxides are used.

[0052] 5 shows a schematic diagram of the state of polymer chains inside the adhesive layer 101b and the elastic layer 101c when silicone oil is applied to the surface of the elastic layer that has not been exposed to UV light. For example, the molecular chain of silicone rubber contains a base polymer (501) that serves as the main chain and side chains (503), each of which has reactive sites (504, 505).

[0053] As shown in Fig. 5, if the elastic layer is simply heat-cured, the crosslink density of the elastic layer is low, so when grease, oil, adhesive, etc. adhere to the surface, the components penetrate between the base polymers (501) (Fig. 6). Then, as shown in Fig. 6, the components push the gaps between the base polymers, causing the elastic layer to expand, or they undergo a crosslinking reaction with the base polymer, increasing the hardness of the elastic layer.

[0054] To prevent this, as shown in Figure 7, when the elastic layer is irradiated with UV (702) from a UV (ultraviolet) lamp (701), the molecular chains are activated, crosslinking (506) occurs, and the crosslink density of the irradiated surface increases. By increasing the crosslink density, the gaps between the base polymers of the elastic layer are less likely to widen, as shown in Figure 7, and even if oil or adhesive adheres to the surface, its components are prevented from penetrating into the elastic layer, as shown in Figure 8. This makes it possible to suppress the expansion and hardening of the elastic layer.

[0055] Also, since only the molecular chains on the surface that are exposed to UV are activated, prolonged UV irradiation may activate most of the molecular chains on the surface, preventing the cross-link density from increasing any further.In addition, if a large amount of curing agent is added to increase the cross-link density of the entire elastic layer, most of the molecular chains that are activated by UV may react with the curing agent, preventing the cross-link density from increasing even with UV irradiation.

[0056] In addition to the methods mentioned above, there are other ways to suppress the expansion of the elastic layer, such as: - Increasing the temperature when baking and hardening the elastic layer, and extending the baking time to further promote the reaction and increase the crosslink density. - Applying the curing agent or adhesive used in creating the elastic layer to the surface, allowing it to penetrate, and then removing and heating it to react with the base polymer and increase the crosslink density. - Irradiating the surface of the elastic layer with an electron beam to activate the molecular chains on the surface, increasing the crosslink density.

[0057] (Explanation of swelling degree and range of swelling degree) The swelling degree is the level at which the elastic layer swells due to the penetration of grease and oil components, which cause the expansion and hardening of the elastic layer, into the elastic layer. The swelling degree is measured and evaluated by the following method. Measurement method: A sample is cut out, and its weight is measured and recorded. Next, the kinematic viscosity at a temperature of 200°C is measured. ２ The sample is immersed in dimethyl silicone oil at 25°C for 12 hours. After immersion, the dimethyl silicone oil adhering to the sample surface is removed and the sample weight is measured. Evaluation method: The swelling degree (%) is calculated using formula 4 from the weight measured using the test method. Swelling degree = (sample weight after immersion) / (sample weight before immersion) x 100 (formula 4) A larger swelling degree value indicates that more dimethyl silicone oil is stored in the elastic layer, and therefore it can be determined that the structure is prone to storing grease and oil, i.e., the crosslink density is low.

[0058] In the fixing belt according to the present disclosure, the elastic layer is exposed on at least one end surface in the longitudinal direction of the fixing belt. The "end surface" refers to the surface that is visible when the fixing belt is observed from the longitudinal direction.

[0059] When the total length of the fixing belt in the longitudinal direction is W, the region from the center to both ends up to W / 3 is the central region B, and the region closer to the ends than the central region B is the end region A (see FIG. 9). Of the end region A, the region including the end surface where the elastic layer is exposed is the end region A1, and in FIG. 9, the end regions A at both ends are the end region A1. Furthermore, when the swelling degree of the elastic layer in the central region B is QB [%], within the end region A1, there exists a region C with a width of 1 mm or more in the longitudinal direction, which shows a swelling degree QC [%] that satisfies the following formula 1: QC<QB (Formula 1) [where QC is the swelling degree of the elastic layer in region C when the elastic layer has a kinetic viscosity of 10 m s at a temperature of 200°C. ２ / s at a temperature of 25°C for 12 hours.]

[0060] By setting the degree of swelling of the end regions of the elastic layer lower than that of the central region, it becomes difficult for grease and oil components to penetrate from the ends, and damage to the fixing belt can be suppressed.

[0061] To prevent swelling, it is preferable that the swelling degree QC satisfy the following formula 2: 100≦QC≦110 (Formula 2) If QC is greater than 110%, grease and oil components will easily penetrate into the elastic layer. If used for a long period of time in this state, the strength will decrease as the elastic layer swells, causing breakage.

[0062] On the other hand, it is preferable that the swelling degree QB in the central region B for image formation satisfies the following formula 3: 115≦QB≦125 (Formula 3) If QB is less than 115%, the surface of the elastic layer becomes too hard, and when fixing to a recording medium with an uneven surface, the elastic layer cannot follow the unevenness of the surface of the recording medium, resulting in poor image quality. If QB is more than 125%, the elastic layer becomes too soft, resulting in poor life at the edge of the recording medium.

[0063] (3) Adhesive Layer The adhesive layer 101b uses an addition-curing silicone rubber adhesive. These contain uncrosslinked silicone rubber components, which, when heated, bond with the uncrosslinked components of the inner surface treatment layer of the surface layer (described below) and the elastic layer, thereby bonding the surface layer and the elastic layer. Furthermore, if the amount of UV irradiation on the elastic layer surface is low and the surface crosslinking density is low, much of the uncrosslinked silicone rubber components in the adhesive will migrate into the elastic layer, reducing the adhesive function between the surface layer and the elastic layer.

[0064] (4) Surface Layer The surface layer 101a contains tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) and perfluoropolyether (PFPE). A fluororesin material with a thickness of 100 μm or less, preferably 10 to 70 μm, can be used. Examples of fluororesin layers include PTFE, FEP, and PFA. The inner surface of the surface layer 101a can be pre-treated with sodium, excimer laser, ammonia, or plasma etching to improve adhesion. In this example, a 20 μm-thick PFA tube obtained by extrusion molding was used. The inner surface of the tube was pre-treated with plasma etching to improve wettability with the adhesive, which will be described later.

[0065] An image forming apparatus that can use the above-mentioned fixing belt and fixing device will be described. Fig. 11 is a cross-sectional view of a color electrophotographic image forming apparatus according to at least one embodiment of the present disclosure, taken along the direction in which a recording material is conveyed. In this disclosure, the electrophotographic image forming apparatus is also simply referred to as a "printer."

[0066] The printer shown in FIG. 11 includes image forming units 10 for the colors Y (yellow), M (magenta), C (cyan), and Bk (black). A photosensitive drum (photoconductor) 11 is pre-charged by a charger 12. The photosensitive drum 11 is then exposed by a laser scanner 13, forming an electrostatic latent image. The electrostatic latent image is then converted into a toner image by a developer 14. The toner image on the photosensitive drum 11 is sequentially transferred by a primary transfer blade 17 to an image carrier, such as an intermediate transfer belt 31. After transfer, any toner remaining on the photosensitive drum 11 is removed by a cleaner 15. As a result, the surface of the photosensitive drum 11 is cleaned in preparation for the next image formation.

[0067] The recording material P is fed one sheet at a time from the paper feed cassette 20 or the multi-paper feed tray 25 in the direction of arrow 3 and fed into a pair of registration rollers 23. The pair of registration rollers 23 first receive the recording material P and straighten it if it is skewed. The pair of registration rollers then synchronize with the toner image on the intermediate transfer belt 31 and feed the recording material P between the intermediate transfer belt 31 and a secondary transfer roller 35. The color toner image on the intermediate transfer belt is transported to a secondary transfer section by a pair of secondary transfer rollers 34 and transferred onto the recording material P by a transfer body, such as the secondary transfer roller 35. The color toner image on the recording material P is then fixed to the recording material P by heating and pressing the recording material P by a fixing unit 40.

[0068] [Example 1] (Method for manufacturing a fixing belt) Next, a method for manufacturing a fixing member used in this example will be described. In this example, a fixing belt as shown in FIG. 4 was manufactured by a manufacturing method consisting of steps 1 to 6.

[0069] (Step 1) A stainless steel mold with an inner diameter of 25 mm and a width of 2000 mm was prepared. A polyimide precursor coating was applied to the mold and baked at 200°C for 60 minutes. The polyimide coating was peeled off from the surface of the stainless steel mold to obtain an endless belt-shaped polyimide resin substrate with an inner diameter of 25 mm, a film thickness of 60 μm, and a length of 400 mm. The outer peripheral surface of this substrate was treated with a primer.

[0070] (Step 2) A filler-free, addition-curing liquid silicone rubber (product name: SE1886, manufactured by Dow Corning Toray Co., Ltd.) was prepared as a raw material for forming the elastic layer. This was a two-component type in which the base material was a vinyl-containing organopolysiloxane and the curing agent was a hydrogen organopolysiloxane. Spherical alumina (product name: Alnabeads CB-A30S, manufactured by Showa Denko K.K.) was added to this liquid silicone rubber as a spherical filler. Thus, an addition-curing silicone rubber composition for forming the elastic layer was prepared. This was applied to the outer peripheral surface of the substrate using a ring coating method and then heated at 200°C for 4 hours to crosslink the layer of the addition-curing silicone rubber composition, forming a 300 μm-thick elastic layer. The tensile modulus of this elastic layer was 1.2 N / mm ２ This is what happened.

[0071] (Step 3) While the substrate on which the elastic layer was formed was rotated in the circumferential direction at a moving speed of 20 mm / sec, the surface of the elastic layer was irradiated with ultraviolet light in an atmospheric air using an ultraviolet lamp positioned at a distance of 10 mm from the surface of the elastic layer. The ultraviolet lamp used was a low-pressure mercury ultraviolet lamp (product name: GLQ500US / 11, manufactured by Toshiba Lighting & Technology Corporation), and the integrated light amount of a wavelength of 185 nm on the irradiated surface was 800 mJ / cm. ２ The irradiation time was set to 360 seconds so that the above condition was met.

[0072] (Step 4) An addition-curing silicone rubber adhesive (product name: SE1819CV, a mixture of equal amounts of "liquid A" and "liquid B" manufactured by Dow Corning Toray Co., Ltd.) was applied to the surface of the elastic layer to a thickness of approximately 5 μm.

[0073] (Step 5) A 20 μm fluororesin tube (Gunze Ltd., 959HP-PLUS) with a hydrophilic inner surface was placed over the belt, and the belt surface was uniformly rubbed from above the fluororesin tube to remove excess adhesive from between the elastic layer and the fluororesin tube. The belt was then placed in an electric furnace set at 200° C. and heated for 1 hour to harden the adhesive, bonding the fluororesin tube to the elastic layer, and both ends were cut. By cutting both ends, the elastic layer was exposed on the belt end surfaces.

[0074] (Step 6) A metal thin film was applied to the belt obtained in the previous step, covering the area 5 mm inward from both ends, so that only the 5 mm wide area from both ends was exposed. The exposed area was then irradiated with ultraviolet light for 60 seconds using the same method as in step 3, to obtain a fixing belt. Although a metal thin film was applied in this case, the shielding material and method are not important as long as ultraviolet light can be irradiated only in the area 5 mm from both ends of the fixing belt.

[0075] Example 2 The ultraviolet irradiation time in step 3 of Example 1 was changed to 420 seconds. Otherwise, the same method as in Example 1 was used to produce and evaluate the product.

[0076] Example 3 The ultraviolet irradiation time in step 3 of Example 1 was changed to 300 seconds, and the ultraviolet irradiation time in step 6 was changed to 120 seconds. Otherwise, the same method as in Example 1 was used to produce and evaluate the product.

[0077] [Example 4] Instead of performing step 6 shown in Example 1, the adhesive used in step 4 was applied to the end of the fixing belt, and after leaving it for 30 seconds, it was wiped off and baked for 10 minutes in an electric furnace at 200° C. Except for this, the fixing belt was manufactured and evaluated in the same manner as in Example 1.

[0078] Comparative Example 1 A product was produced and evaluated in the same manner as in Example 1, except that step 6 in Example 1 was not carried out.

[0079] Comparative Example 2 A film was produced and evaluated in the same manner as in Example 1, except that the ultraviolet irradiation time in step 3 of Example 1 was changed to 480 seconds and step 6 was not carried out.

[0080] [Comparative Example 3] The belt obtained in step 2 of Example 1 was covered with a metal thin film in 10 mm wide regions from both ends, and in this state, ultraviolet light was irradiated for 360 seconds in the same manner as in step 3 of Example 1. Next, step 4 of Example 1 was performed without performing step 3. Otherwise, the belt was produced in the same manner as in Example 1, and evaluation was carried out.

[0081] Comparative Example 4: The amount of the silicone rubber curing agent used in step 2 was reduced, and the tensile strength of the elastic layer was 0.4 N / mm ２ The ultraviolet irradiation time in step 3 of Example 1 was changed to 600 seconds. Except for this, the same method as in Example 1 was used for production and evaluation.

[0082] Comparative Example 5: The amount of the silicone rubber curing agent used in step 2 was increased, and the tensile strength of the elastic layer was 2.0 N / mm ２ The other conditions were the same as in Example 1, and the evaluation was carried out.

[0083] The method for measuring the physical properties of the elastic layer in the present disclosure is described below. (Oil Swelling Test) The swelling degree of the elastic layer was evaluated using the prepared fixing member. The evaluation conditions were as follows: Test environment: room temperature 25°C, humidity 50% Silicone oil: kinetic viscosity of 10 mJ at a temperature of 200°C ２ Dimethyl silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., product name KF-96-1000CS) satisfying the above requirement was used. Sample Preparation Method: First Sample: When the total length of the fixing belt is W, from the center toward both ends in the longitudinal direction of the fixing belt, the elastic layer was sampled from the fixing belt within a central region B from the center to W / 3 using the following method. The sampled elastic layer was separated using the following method and cut into a rectangular parallelepiped shape measuring 2500 μm in length (circumferential direction of the fixing belt), 1000 μm in width, and 250 μm in thickness. Elastic Layer Separation Method: 1. A razor is inserted between the elastic layer and the base layer, and the elastic layer and layer structure are peeled off from the base layer. 2. A razor is inserted between the elastic layer and the surface layer, and the elastic layer and layer structure are separated. For the second sample, the elastic layer in the end region A1 was separated from the fixing belt in the same manner as for the first sample and cut into a rectangular parallelepiped shape measuring 2,500 μm in length (circumferential direction of the fixing belt), 1,000 μm in width, and 250 μm in thickness. The swelling ratio of each sample was measured, and the presence or absence of a sample that satisfied the requirements of Equation 1 was confirmed for the separately obtained QB. If the cut samples showed differences in swelling ratio in the horizontal direction, the cutting point was shifted to create 1 mm-wide samples with no variation in swelling ratio, and measurements were then performed.

[0084] (Measurement of Tensile Modulus) A tensile test specimen of the elastic layer in the central region B of a fixing belt with a total length W, extending from the center of the belt to W / 3 toward both ends in the longitudinal direction, was isolated from the fixing belt using the following method: 1. A razor was inserted between the elastic layer and the base layer to peel off the elastic layer and the surface layer from the base layer. 2. A razor was inserted between the elastic layer and the surface layer to separate the elastic layer from the surface layer. The tensile modulus was measured using a method in accordance with JIS K 6251:2017. Specifically, the isolated elastic layer was punched into a dumbbell-shaped No. 8 cut, and the film thickness of the sample was measured using a micrometer. After measurement, the sample was placed in an Autograph AG-X (manufactured by Shimadzu Corporation) and tested at a tensile speed of 200 mm / min at room temperature. The tensile modulus was measured by creating a graph from the measurement results with the strain of the sample on the horizontal axis and the tensile stress on the vertical axis, and the slope of the linear approximation of the measurement data over a strain range of 0 to 10% was used.

[0085] Next, the evaluation method in this example will be described. (Evaluation 1: Durability Evaluation) Using the prepared fixing member, the fixing device shown in FIG. 2 was installed in a modified digital commercial printing printer (product name: imageRUNNER ADVANCE C5560, manufactured by Canon Inc.), and evaluation was performed. The evaluation conditions were as follows: Test environment: room temperature 23°C, humidity 50%; Process speed: 200 mm / sec (s); Print speed: 30 sheets / min; Paper passing conditions: a grid image was formed on GF-C081 (manufactured by Nippon Paper Industries Co., Ltd., 81g paper, A4 size), and the paper was passed continuously. The end of the fixing belt and the paper edge on the outer periphery of the fixing belt were observed every 100,000 sheets, and fracture of the elastic layer at the end was confirmed. (Evaluation Criteria) Rank A: The elastic layer did not break after 400,000 sheets or more. Rank B: The elastic layer did not break after 300,000 sheets or more. Rank C: The elastic layer did not break after 200,000 sheets or more. Rank D: The elastic layer broke after less than 200,000 sheets.

[0086] (Evaluation 2: Image Quality Evaluation (Evaluation of Melting Unevenness)) After fixing a toner image formed on paper, the molten state of the toner can be observed as an index of the ability of the fixing member to follow the paper irregularities. Using the fixing belt 101 prepared in the same manner as in the durability evaluation, and the fixing device shown in FIG. 2, 10 sheets of images for evaluating melting unevenness are fixed consecutively under an environment of a temperature of 10°C and a relative humidity of 50%. The paper used was A4-size recycled paper (product name: Recycled Paper GF-R100; manufactured by Canon Inc., thickness 92 μm, basis weight 66 g / m ２ The paper used had a recycled paper content of 70%, and a Beck smoothness of 23 seconds (measured according to JIS P8119). The image used for evaluating uneven melting was a 10 mm x 10 mm patch image formed with 100% cyan and magenta toners, placed near the center of the paper. As a measure of uneven melting, sufficient heat and pressure were applied to the image area where the two colors were formed, causing the toner to melt and mix. In particular, in the recesses of the paper's unevenness, if heat is applied but pressure is not, the toner grain boundaries remain after fixing, resulting in insufficient color mixing and causing uneven melting. If the fixing member cannot adequately conform to the unevenness, pressure is applied to the raised areas, causing color mixing, but insufficient color mixing in the recesses. Therefore, the ability to follow the unevenness was confirmed by observing the melting state of the image-formed area. After printing 10 consecutive sheets of images for evaluating uneven melting, a sample was taken from the 10th sheet, and the image-formed area was observed under an optical microscope to evaluate uneven melting. The evaluation criteria are as follows: (Evaluation Criteria) Rank A: No toner grain boundaries are visible even in the recesses of the paper fibers, and the colors are mixed in both the recesses and protrusions. Rank B: Some toner grain boundaries are observed in the recesses of the paper fibers, but the colors are mostly mixed in both the recesses and protrusions. Rank C: Only the protrusions of the paper fibers are mixed, and many toner grain boundaries are observed in the recesses.

[0087] (Evaluation 3: Adhesion Strength Evaluation) The effect of UV irradiation on the elastic layer can be evaluated by evaluating the adhesive strength between the elastic layer 101c and the surface layer 101a. The evaluation method conformed to JIS Z0237 2009 and used a peeling tester, "Vertical Automatic Measurement MV-1000N; manufactured by Imada." Test environment: Room temperature of 25°C, humidity of 50%. Sample preparation method: As shown in FIG. 9, when the total length of the fixing belt 101 is W, a 10 mm-wide cut was made in the surface layer and elastic layer in the circumferential direction of the fixing belt in the central region extending from the center of the fixing belt in the longitudinal direction to W / 3 toward both ends using a feather cutter (901). Next, a single cut was made between the cuts in a direction parallel to the longitudinal direction of the fixing belt (902). As shown in FIG. 10, a cut was made from this cut to the interface between the elastic layer 101c and the fluororesin tube 101a at the end of the fixing belt using a feather cutter (901). The surface layer side was then measured for 90-degree peeling strength at the interface between the elastic layer and the fluororesin tube using a testing machine with a pulling speed of 1 mm / s in the direction 903 and a sample width of 10 mm. The evaluation criteria were as follows: Rank A: Peeling strength of 2.0 N / cm or more Rank B: Peeling strength of less than 2.0 N / cm

[0088] Table 1 shows the results of this example and the comparative example.

[0089] In Comparative Examples 1 to 5, there was no region (region C) exhibiting a swelling degree that satisfied Formula 1, so the swelling degree measured in the end region A1 is shown.

[0090] The present disclosure is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the present disclosure. Therefore, the following claims are appended to apprise the public of the scope of the present disclosure.

[0091] This application claims priority based on Japanese Patent Application No. 2024-088214 filed on May 30, 2024 and Japanese Patent Application No. 2025-074158 filed on April 28, 2025, the entire contents of which are incorporated herein by reference.

[0092] 100, 200, 300: Fixing device 101: Fixing belt 101a: Surface layer 101b: Adhesive layer 101c: Elastic layer 101d: Base layer 101d: Resin layer 105: Pressure roller 10: Image forming unit 11: Photosensitive drum 12: Charger 13: Laser scanner 14: Developing unit 15: Cleaner 17: Primary transfer blade 20: Paper feed cassette 25: Multi-paper feed tray 23: Registration roller pair 31: Intermediate transfer belt 34: Secondary transfer roller pair 35: Secondary transfer roller 40: Fixing unit 41: Fixing film P: Recording material

Claims

1. A fixing belt having a total length in the longitudinal direction of W, which has a base layer, an elastic layer, and a surface layer, the elastic layer is exposed on at least one end surface in the longitudinal direction of the fixing belt, the region from the center of the longitudinal direction of the fixing belt to W / 3 toward each end is defined as a central region B, the region closer to the end than the central region B is defined as an end region A, the region of the end region A including the end surface where the elastic layer is exposed is defined as an end region A1, the elastic layer in the central region B is formed by a kinetic viscosity of 10 m / s at a temperature of 200°C. ２ The fixing belt is characterized in that, when the degree of swelling when the fixing belt is immersed in dimethyl silicone oil having a kinematic viscosity of 10 m / s at a temperature of 25° C. for 12 hours is QB [%], the end region A1 has a region C having a width of 1 mm or more in the longitudinal direction, the region C exhibiting a degree of swelling QC [%] that satisfies the following formula 1: QC<QB (Formula 1) [wherein QC is the degree of swelling when the elastic layer in the region C is immersed in dimethyl silicone oil having a kinematic viscosity of 10 m / s at a temperature of 200° C.] ２ / s at a temperature of 25°C for 12 hours.] 2. The fixing belt according to claim 1, wherein QB and QC satisfy the following formulas 2 and 3: 100≦QC≦110 (Formula 2) 115≦QB≦125 (Formula 3) 3. The tensile modulus of elasticity measured by a tensile test piece of the elastic layer sampled from the central region B of the elastic layer is 0.5 N / mm ２ 1.2N / mm or more ２ 3. The fixing belt according to claim 1, wherein:

4. A fixing device comprising the fixing belt according to any one of claims 1 to 3, a pressing member disposed on the inner peripheral surface of the fixing belt and having a sliding surface that contacts the inner peripheral surface of the fixing belt via grease containing silicone oil, and a pressure member that forms a fixing nip portion between the fixing belt and the pressing member.

5. The fixing device according to claim 4, wherein the pressing member is a heating member.

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