Fixing belt, and fixing device

Abstract

To eliminate the risk of damage resulting from lubricant leaking from a fixing belt end, the lubricant adhering to an elastic layer, which is exposed at the belt end, and subsequently penetrating and swelling the elastic layer when continuously used in this manner.SOLUTION: Provided is a fixing belt having a total length W, in which an elastic layer is exposed at least at one longitudinal end surface. A central region B extends from the longitudinal center of the fixing belt toward each end up to W / 3, and a region located closer to the ends than the central region B is defined as an end region A. Among the end regions A, a region including an end surface where the elastic layer is exposed is defined as an end region A1. When a swelling degree QB (%) of the elastic layer in the central region B is determined by immersing, for 12 hours at 25°C, the elastic layer in a dimethyl silicone oil having a kinematic viscosity of 10 m2 / s at 200°C, the end region A1 includes, over a width of 1 mm or more in the longitudinal direction, a region C exhibiting a swelling degree QC (%) that satisfies QC<QB.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[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. [Background technology]

[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" or "paper") to the paper by applying heat and pressure to the toner image. 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 the fixing process 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 the fixing belt to have a low thermal capacity and be made smaller, which not only makes the fixing device more energy-efficient but also shortens the time (warm-up time) required for the fixing belt to reach a predetermined temperature sufficient for heat-fixing 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. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2020-197701 Summary of the Invention [Problem to be solved by the invention]

[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 edges. However, when used for a long period of time or when a large amount of lubricant is used, the grooves are unable to stop the lubricant, and it leaks out from the belt edges, penetrating into the elastic layer from the edges, so it can be said that this measure is insufficient.

Means for Solving the Problem

[0010] The present disclosure is directed to providing a fixing belt that can prevent the lubricant leaking from the end of the fixing belt from entering the elastic layer even when it adheres to the exposed elastic layer at the end of the fixing belt, and maintain its strength by not swelling the elastic layer.

[0011] The present disclosure is a fixing belt having a base layer, an elastic layer, and a surface layer, and having a total length of W in the longitudinal direction, wherein at least one end face in the longitudinal direction of the fixing belt has the elastic layer exposed, a region from the center to both ends of the fixing belt in the longitudinal direction up to W / 3 is defined as a central region B, a region closer to the end than the central region B is defined as an end region A, a region including the end face where the elastic layer is exposed in the end region A is defined as an end region A1, when the swelling degree of the elastic layer in the central region B when immersed in dimethyl silicone oil having a kinematic viscosity of 10 m<x , , 2 ,

[0012] , , ,

[0013] , , 2 , , , , / s at 200°C for 12 hours at 25°C is defined as QB [%], the fixing belt is characterized in that in the end region A1, there exists a region C showing a swelling degree QC [%] satisfying the following formula 1 with a width of 1 mm or more in the longitudinal direction. QC < QB (Formula 1) [In the formula, QC represents the swelling degree (%) of the elastic layer in the region C when immersed in dimethyl silicone oil having a kinematic viscosity of 10 m 2 / s at 200°C for 12 hours at 25°C.]<00​​​​​​​​ 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. [Brief explanation of the drawings]

[0014] [Figure 1] 2 is a schematic diagram of a fixing device according to the present embodiment. [Figure 2] 2 is a schematic diagram of a fixing device according to the present embodiment. [Figure 3] 2 is a schematic diagram of a fixing device according to the present embodiment. [Figure 4] FIG. 2 is a cross-sectional view of a fixing belt according to the present embodiment. [Figure 5] This is a diagram showing silicone oil applied to the surface of an elastic layer that has not been exposed to UV light. [Figure 6] FIG. 10 is a diagram of an elastic layer in which silicone oil has been applied to the surface of the elastic layer that has not been exposed to UV light and has been left standing. [Figure 7] FIG. 10 is a diagram showing the surface of an elastic layer irradiated with UV light. [Figure 8] FIG. 10 is a diagram of an elastic layer in which silicone oil has been applied to the surface of the elastic layer after UV irradiation and then allowed to stand. [Figure 9] FIG. 1 is a diagram of procedure 1 of the peeling test (including indication of longitudinal lengths W and W / 3, end region A, region C, and end region B). [Figure 10] This is a diagram of step 2 of the peeling test. [Figure 11] FIG. 1 is a schematic diagram of an image forming apparatus according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[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 for 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. 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, a 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 portion 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 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 circumferential 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 rotation axis direction are rotatably supported by fixed parts (not shown) such as a frame of the fixing device 100. Furthermore, a reflective member 104 that reflects light emitted from the halogen heater 103 back to the fixing belt 101 is provided inside 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 located 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. As a result, the recording material P in contact with the outer 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.

[0025] Another fixing device of this embodiment will be described with reference to FIG. 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 with the fixing belt 101.

[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 is fixed and supported, 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 by 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 stay 204 supports the belt guide / heater holder 202.

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

[0031] A semi-solid lubricant (grease) (not shown) consisting of a solid component (thickener) and a base oil component (oil) is applied to the inner surface of the fixing belt 101, ensuring the sliding properties between the ceramic heater 203 and the sliding layer on the inner surface of the fixing belt 101. The pressure roller 105 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 also 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. The fixing device 300 of this embodiment uses an IH (electromagnetic induction heating) 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 portion 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 at a predetermined interval to cover the outer surface of the fixing belt 101 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 of the fixing belt 101, which will be described later. The base layer 101d generates heat, and the fixing belt 101 is heated. In addition, the belt guide 304 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 property 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 the 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) 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 is, for example, the one described with reference to FIG.

[0040] In this way, 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] Next, the fixing belt will be described in detail. 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 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 within 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 More than 1.2N / mm 2 The following is preferably used: Tensile modulus of elasticity 0.5 N / mm 2 If the load is less than 1.2N / mm, the elastic layer becomes too soft and the life of the paper edge 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] Specific examples include non-conductive fillers such as silicon carbide (SiC), silicon nitride (Si3N4), silica (SiO2), boron nitride (BN), aluminum nitride (AlN), alumina (Al2O3), iron oxide (Fe2O3), zinc oxide (ZnO), magnesium oxide (MgO), and titanium oxide (TiO2).

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

[0052] Figure 5 shows a schematic diagram of the state of polymer chains inside adhesive layer 101b and 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 Figure 5, if the elastic layer is simply heat-cured, the cross-link 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) (Figure 6). Then, as shown in Figure 6, the components push apart the base polymers, causing the elastic layer to expand, or they undergo a cross-linking reaction with the base polymers, 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, causing crosslinks (506), increasing the crosslink density of the irradiated surface. 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, because only the molecular chains on the surface 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 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 above methods, the following methods can be used to suppress the expansion of the elastic layer. By increasing the temperature when baking and hardening the elastic layer and by extending the baking time, the reaction progresses further and the cross-link density increases. The curing agent and adhesive used in creating the elastic layer are applied to the surface, allowed to penetrate, and then removed and heated to react with the base polymer and increase the cross-link density. The surface of the elastic layer is irradiated with an electron beam to activate the molecular chains on the surface, thereby increasing the cross-link density.

[0057] (Explanation of swelling degree and range of swelling degree) The degree of swelling is the level to 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 degree of swelling is measured and evaluated using the following method. Measurement method: Cut out a sample, measure its weight and record it. Then, measure the kinematic viscosity at 200°C to 10m 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 is weighed. Evaluation method: Calculate the swelling degree (%) using formula 4 from the weight measured in the test method. (Equation 4) Swelling degree = (sample weight after immersion) / (sample weight before immersion) × 100 A larger swelling value indicates that more dimethyl silicone oil is stored in the elastic layer, and therefore it can be determined that the structure is more likely to store grease and oil, in other words, 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 regions from the center to both ends up to W / 3 are the central region B, and the regions closer to the ends than the central region B are the end regions A (see Fig. 9). Among the end regions A, the region including the end face where the elastic layer is exposed is the end region A1, and in Fig. 9, the end regions A at both ends become the end regions A1. Also, when the swelling degree of the elastic layer in the central region B is QB [%], in the end region A1, there exists a region C showing a swelling degree QC [%] that satisfies the following formula 1, with a width of 1 mm or more in the longitudinal direction. QC < QB (Formula 1) [In the formula, QC represents the swelling degree (%) when the elastic layer in the region C is immersed in dimethyl silicone oil with a kinematic viscosity of 10 m 2 / s at a temperature of 200 °C for 12 hours at a temperature of 25 °C.]<00D02D7>

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

[0061] The swelling degree QC preferably satisfies the following formula 2 in order to suppress swelling. 100 ≤ QC ≤ 110 (Formula 2) When QC becomes larger than 110%, grease and oil components easily penetrate into the elastic layer. When used for a long time in this state, the strength decreases due to the swelling of the elastic layer, causing damage. <0000D02D5>

[0062] On the other hand, the swelling degree QB in the central region B related to image formation preferably satisfies the following formula 3. 115 ≤ QB ≤ 125 (Formula 3) When QB is smaller than 115%, the surface of the elastic layer becomes too hard and cannot follow the unevenness of the surface of the recording medium with unevenness on the surface when fixing, resulting in deterioration of image quality. When QB is larger than 125%, the elastic layer becomes too soft and the life at the edge of the recording medium deteriorates.

[0063] (3) Adhesive layer The adhesive layer 101b is made of an addition-curing silicone rubber adhesive, which contains uncrosslinked silicone rubber components and, when heated, bonds with the uncrosslinked components of the inner surface treatment layer of the surface layer (described later) and the elastic layer, thereby bonding the surface layer and the elastic layer together. Furthermore, if the amount of UV irradiation on the surface of the elastic layer is small and the surface crosslinking density is low, much of the uncrosslinked silicone rubber 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 having a thickness of 100 μm or less, preferably 10 to 70 μm, can be used. Examples of the fluororesin layer include PTFE, FEP, and PFA. The adhesiveness of the inner surface of the surface layer 101a can be improved by previously treating it with sodium, excimer laser, ammonia, or plasma etching. In this example, a 20 μm-thick PFA tube obtained by extrusion molding was used. The inner surface of the tube was plasma-etched to improve wettability with the adhesive, which will be described later.

[0065] An image forming apparatus that can use the above-described fixing belt and fixing device will now be described. 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 the present 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, and an electrostatic latent image is formed on the photosensitive drum 11. The electrostatic latent image is then converted into a toner image by a developing unit 14. The toner images on the photosensitive drum 11 are 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 becomes clean and is prepared for the next image formation.

[0067] Recording materials P are fed one by one from a paper feed cassette 20 or a 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 of manufacturing a fixing belt) Next, a method for producing the fixing member used in this example will be described. In this example, a fixing belt as shown in FIG. 4 was produced by a manufacturing method consisting of steps 1 to 6.

[0069] (Process 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 surface of this substrate was treated with a primer.

[0070] (Process 2) As a raw material for forming the elastic layer, a filler-free addition-curing liquid silicone rubber (product name: SE1886, manufactured by Toray Dow Corning Co., Ltd.) was prepared. This was a two-component type in which the main component was a vinyl-containing organopolysiloxane and the curing agent was a hydrogen organopolysiloxane. Spherical alumina (product name: ALUNABEAD 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 the 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) The substrate on which the elastic layer was formed was rotated in the circumferential direction at a speed of 20 mm / s, and ultraviolet light was irradiated onto the surface of the elastic layer in an atmospheric environment using an ultraviolet lamp positioned 10 mm away 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 intensity of the 185 nm wavelength on the irradiation surface was 800 mJ / cm. 2 The irradiation time was set to 360 seconds so that

[0072] (Step 4) An addition-curing silicone rubber adhesive (product name: SE1819CV, a mixture of equal parts 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 excess adhesive was squeezed out from between the elastic layer and the fluororesin tube by uniformly pressing the belt surface over 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 off. By cutting both ends, the elastic layer was exposed on the belt end surfaces.

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

[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 for production and evaluation.

[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. Other than that, it was manufactured and evaluated in the same manner as in Example 1.

[0078] [Comparative Example 1] The 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 The ultraviolet irradiation time in step 3 of Example 1 was changed to 480 seconds, and step 6 was not performed. Except for this, the same method as in Example 1 was used for production and evaluation.

[0080] Comparative Example 3 The belt obtained in step 2 of Example 1 was covered with a metal thin film in a 10 mm wide region from each end, and in this state, ultraviolet light was irradiated for 360 seconds using the same method as in step 3 of Example 1. Next, step 4 of Example 1 was performed without performing step 3. Otherwise, the belt was produced and evaluated using the same method as in Example 1.

[0081] Comparative Example 4 The amount of silicone rubber hardener used in process 2 was reduced, and the tensile strength of the elastic layer was reduced to 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 Increasing the amount of silicone rubber hardener used in step 2, the tensile strength of the elastic layer was increased to 2.0 N / mm 2 Other than that, the same method as in Example 1 was used for production and evaluation.

[0083] The physical properties of the elastic layer in the present disclosure are measured as follows. (Oil swelling test) The swelling degree of the elastic layer was evaluated using the prepared fixing member under the following conditions. Test environment: room temperature 25°C, humidity 50% Silicone oil; kinematic viscosity at 200°C is 10m 2 Dimethyl silicone oil that satisfies the / s requirement (Shin-Etsu Chemical Co., Ltd., product name KF-96-1000CS) Sample preparation method; First sample: When the total length of the fixing belt from the center toward both ends in the longitudinal direction of the fixing belt is W, the elastic layer was sampled from the fixing belt within a range of 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. Insert a razor between the elastic layer and the base layer and peel the elastic layer and layer structure from the base layer. 2. A razor is inserted between the elastic layer and the surface layer to separate the elastic layer from the layer structure. Second sample: The elastic layer in the end region A1 was separated from the fixing belt in the same manner as the first sample, 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. The swelling ratio of each sample is measured, and the separately obtained QB is checked to see if any samples satisfy the requirements of Equation 1. If the cut sample has a difference in swelling ratio in the horizontal direction, shift the cutting point to create a 1 mm wide sample with no variation in swelling ratio, and then perform the measurement.

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

[0085] Next, the evaluation method in this example will be described. (Rating 1: Durability rating) The fixing device shown in Fig. 2 was installed using the prepared fixing member in a modified digital commercial printing printer (product name: imageRUNNER ADVANCE C5560, manufactured by Canon Inc.) and evaluated under the following evaluation conditions. Test environment: room temperature 23°C, humidity 50% Process speed: 200 mm / sec (s) Print speed: 30 pages / minute Paper passing conditions: A grid image is formed on GF-C081 (manufactured by Nippon Paper Industries Co., Ltd., 81 g paper, A4 size), and the paper is passed continuously. The edges of the fixing belt and the paper edge on the outer periphery of the fixing belt were observed every 100,000 sheets to check for breakage of the elastic layer at the edges. (Evaluation criteria) Rank A: The elastic layer has not broken after 400,000 or more sheets. Rank B: Over 300,000 sheets with no breakage of the elastic layer Rank C: The elastic layer has not broken after 200,000 or more sheets. Rank D: The elastic layer breaks after printing less than 200,000 sheets.

[0086] (Evaluation 2: Image quality evaluation (melting unevenness evaluation)) By observing the melted state of the toner after fixing the toner image formed on the paper, it is possible to obtain an index of the ability of the fixing member to follow the unevenness of the paper. Using the fixing belt 101 prepared in the same manner as in the durability evaluation, 10 sheets of evaluation images for melting unevenness were fixed in succession using the fixing device shown in FIG. 2 under an environment of a temperature of 10°C and a relative humidity of 50%. The paper used was A4-sized recycled paper (product name: Recycled Paper GF-R100; manufactured by Canon Inc., thickness 92 μm, basis weight 66 g / m). 2 The paper used was 70% recycled paper, with a Beck smoothness of 23 seconds (measured using a method conforming to JIS P8119). The image used to evaluate uneven melting was a 10mm x 10mm patch image formed with cyan toner and magenta toner at 100% concentration, placed near the center of the paper. As a guideline for uneven melting, sufficient heat and pressure must be applied to the image area where two colors are formed, causing the toner to melt and mix. In particular, if heat is applied but no pressure is applied to the concave areas of the paper, the toner grain boundaries remain after fixing, resulting in insufficient color mixing and uneven melting. If the fixing member cannot adequately conform to the concave and convex surfaces, pressure is applied to the convex areas, causing color mixing, but insufficient color mixing in the concave areas. Therefore, conformability to the concave and convex surfaces was confirmed by observing the melting state of the image-forming area. After printing 10 sheets of images in succession to evaluate uneven melting, the 10th sample was taken out and the image-formed area was observed under an optical microscope to evaluate uneven melting. The evaluation criteria were as follows: (Evaluation criteria) Rank A: Toner grain boundaries are not visible even in the recesses of the paper fibers, and the colors are mixed in both the recesses and protrusions. Rank B: Although some toner grain boundaries are observed in the recesses of the paper fibers, the colors are generally mixed in both the recesses and protrusions. Rank C: Only the convex parts of the paper fibers are mixed, and many toner grain boundaries are observed in the concave parts.

[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 was performed in accordance with JIS Z0237 2009 using a peeling measuring instrument, "Vertical Automatic Measurement MV-1000N; manufactured by Imada." Test environment: room temperature 25°C, humidity 50% Sample preparation method; In step 1, as shown in Figure 9, where the total length of fixing belt 101 is W, a 10 mm wide cut is made in the surface layer and elastic layer of the fixing belt in the circumferential direction of the fixing belt in the central region 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 is made parallel to the longitudinal direction of the fixing belt between the cut cutters (902). From this cut, as step 2, as shown in Figure 10, a cut is made with the feather cutter at the interface between elastic layer 101c and fluororesin tube 101a at the end of the fixing belt. Then, the 90-degree peeling strength of the interface between the elastic layer and fluororesin tube was measured using a testing machine, with the surface layer side pulled in the direction 903 at a pulling speed of 1 mm / s and a sample width of 10 mm. The evaluation criteria were as follows: Rank A: Peeling strength is 2.0N / cm or more Rank B: Peeling strength is less than 2.0 N / cm

[0088] Table 1 shows the results of this example and the comparative example. [Table 1] 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 edge region A1 is shown.

[0089] The disclosure of this embodiment includes the following configuration. [Configuration 1] A fixing belt having a total length of W in the longitudinal direction and including a base layer, an elastic layer, and a surface layer, the elastic layer is exposed at least on one end surface of the fixing belt in the longitudinal direction, A region extending from the center of the fixing belt in the longitudinal direction to each end of W / 3 is defined as a central region B, A region closer to the end than the central region B is defined as an end region A, A 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 of the central region B is formed by a viscoelastic material having a kinematic viscosity of 10 m at a temperature of 200°C. 2When the swelling degree when immersed in dimethyl silicone oil with a kinematic viscosity of 10 m / s at a temperature of 25°C for 12 hours is defined as QB [%], In the end region A1, there is a region C showing a swelling degree QC [%] satisfying the following formula 1, existing with a width of 1 mm or more in the longitudinal direction. The fixing belt is characterized by this. QC < QB (Formula 1) [In the formula, QC represents the swelling degree (%) when the elastic layer of the region C is immersed in dimethyl silicone oil with a kinematic viscosity of 10 m / s at a temperature of 25°C for 12 hours.] 2 / s.] [Configuration 2] The fixing belt according to Configuration 1, wherein the QB and the QC satisfy the following formulas 2 and 3. 100 ≤ QC ≤ 110 (Formula 2) 115 ≤ QB ≤ 125 (Formula 3) [Configuration 3] The tensile elastic modulus measured by the tensile test piece of the elastic layer sampled from the central region B of the elastic layer is 0.5 N / mm 2 or more and 1.2 N / mm 2 or less. The fixing belt according to Configuration 1 or 2. <0​​​​​​​​​​​​​​​​​​​​​​​​​​​​​10: Image forming unit 11: Photosensitive drum 12: Charger 13: Laser scanner 14: Developer 15: Cleaner 17: Primary transfer blade 20: Paper cassette 25: Multi-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 of W in the longitudinal direction and including a base layer, an elastic layer, and a surface layer, the elastic layer is exposed at least on one end surface of the fixing belt in the longitudinal direction, A region extending from the center of the fixing belt in the longitudinal direction to each end thereof up to W / 3 is defined as a central region B, A region closer to the end than the central region B is defined as an end region A, A 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 made of a material having a kinematic viscosity of 10 m at a temperature of 200°C. ２ / s at a temperature of 25°C for 12 hours, the degree of swelling is QB [%], The fixing belt is characterized in that 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 swelling degree QC [%] that satisfies the following formula 1: QC<QB (Formula 1) [wherein QC is the kinematic viscosity of the elastic layer in the region C at a temperature of 200°C of 10 m ２ / s at a temperature of 25°C for 12 hours.]

2. The QB and the QC satisfy the following formulas 2 and 3: The fixing belt according to claim 1 . 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. 10. A fixing device comprising: the fixing belt according to claim 1; a pressing member disposed on an 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. 5. The fixing device according to claim 4, wherein the pressing member is a heating member.

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