JP2025181678A - Fixing belt and fixing device - Google Patents

Abstract

When lubricant leaks from the end of a fixing belt and adheres to the exposed elastic layer at the end of the belt, the lubricant penetrates into the elastic layer, causing the elastic layer to swell, which may lead to damage if the belt is continued to be used in this state.
[Solution] A fixing belt having a total length W, in which an elastic layer is exposed on at least one longitudinal end face, and a central region B extending from the center of the fixing belt in the longitudinal direction to each end of W/3, and an end region A being an area closer to the end than the central region B, and an end region A1 being an area of end region A including the end face where the elastic layer is exposed, and when the elastic layer in central region B is immersed in dimethyl silicone oil having a dynamic viscosity of 10 ^m2 /s at a temperature of 200°C for 12 hours at a temperature of 25°C, and the swelling degree is QB [%], in end region A1 there is a region C with a width of 1 mm or more in the longitudinal direction that shows a swelling degree QC [%] that satisfies QC < QB.
[Selected Figure] Figure 7

Description

This disclosure relates to a fixing belt and fixing device used in a fixing device of an electrophotographic image forming apparatus.

Electrophotographic image forming devices are equipped with a fixing device that fixes a toner image formed on a recording material (hereinafter referred to as "paper" or "paper") to the paper by applying heat and pressure. This fixing device is equipped with fixing members such as a heating belt (heating roller) and a pressure roller (pressure belt), and the fixing process is performed at the position where these are pressed against each other (the fixing nip).

One example of a fixing device is a belt (film) heating type device. This device has a heater as the heating element (heat source). It also has an endless fixing belt that contains the heater and rotates as the 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 to heat and fix a toner image.

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. An elastic layer made of heat-resistant rubber such as silicone rubber is provided on top of the fixing belt or roller-shaped substrate.

By providing an elastic layer, when a recording material such as paper with toner transferred to it passes through the fixing nip formed by the pressure contact between two opposing fixing members, namely a heating member and a pressure member, the flexibility of the elastic layer rubber allows the surface of the fixing member to deform in line 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 onto the recording material, resulting in a high-quality image with a high gloss and no uneven fixing.

In such fixing devices, a heat-resistant lubricant such as sliding grease or oil is applied between the inner surface of the fixing belt and the member that rubs against it, maintaining the sliding properties of the fixing belt. With this type of system, over long-term use, the lubricant leaks out from the ends of the fixing belt, adheres to and is absorbed by the elastic layer, causing the elastic layer to swell, weakening it and potentially causing the fixing belt to break.

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

Japanese Patent Application Laid-Open No. 2020-197701

By the way, when grooves are provided on the outer 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 small amounts 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 completely block the lubricant, and it leaks out from the belt edges, penetrating into the elastic layer from the edges, making this an insufficient countermeasure.

This disclosure aims to provide a fixing belt that can maintain its strength by preventing the lubricant from leaking from the end of the fixing belt and adhering to the exposed elastic layer at the end of the fixing belt, thereby preventing the lubricant from penetrating into the elastic layer and causing the elastic layer to swell.

The present disclosure provides a fixing belt having a total length W in a longitudinal direction, the fixing belt 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,
When the elastic layer of the central region B is immersed in dimethyl silicone oil having a kinematic viscosity of 10 m ² /s at 200°C for 12 hours at 25°C, the degree of swelling is QB [%].
The fixing belt is characterized in that the end region A1 has a region C having a swelling degree QC [%] that satisfies the following formula 1, the region C having a width of 1 mm or more in the longitudinal direction.
QC<QB (Formula 1)
[In the formula, QC represents the degree of swelling (%) when the elastic layer in region C is immersed in dimethyl silicone oil having a kinematic viscosity of 10 m ² /s at 200°C at 25°C for 12 hours.]

The present disclosure also relates to a fixing device comprising a fixing belt, 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 pressing member and the fixing belt.

This disclosure makes it possible to prevent belt damage even when lubricant leaks from the belt end during long-term use of the fixing device.

2 is a schematic diagram of a fixing device according to the present embodiment. 2 is a schematic diagram of a fixing device according to the present embodiment. 2 is a schematic diagram of a fixing device according to the present embodiment. FIG. 2 is a cross-sectional view of a fixing belt according to the present embodiment. FIG. 10 is a diagram showing a state in which silicone oil is applied to the surface of an elastic layer that has not been exposed to UV light. FIG. 10 is a diagram of an elastic layer in which silicone oil is applied to the surface of the elastic layer that has not been irradiated with UV light and then allowed to stand. FIG. 10 is a diagram showing the surface of an elastic layer irradiated with UV light. FIG. 10 is a diagram of an elastic layer in which silicone oil is applied to the surface of the elastic layer after UV irradiation and the layer is left standing. 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). FIG. 1 is a diagram showing procedure 2 of the peeling test. FIG. 1 is a schematic diagram of an image forming apparatus according to an embodiment.

Embodiments of the present disclosure will be described below with reference to the drawings, but the scope of the present disclosure is not limited to these embodiments, and modifications that do not impair the spirit of the present disclosure are also included in the present disclosure.

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

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.

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. In addition to a halogen heater, a resistance heating element, a carbon heater, or the like may also be used as a heat source for heating the fixing belt 101.

The fixing belt 101 is an endless belt whose cylindrical polyimide resin base is rotated in accordance with the rotation of the pressure roller 105 while its inner surface is rubbed against the belt guide/pressure member 102 during use.

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

A semi-solid lubricant (grease) or oil composed 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 slidability between the belt guide/pressure member 102, which has a sliding surface, and the sliding layer on the inner surface of the fixing belt 101.

The fixing belt 101 is heated by the halogen heater 103 to a predetermined temperature required to melt the toner on its surface. This predetermined temperature is detected by a thermistor (108) serving 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 using a controller (not shown). This thermistor may also be located on the inner surface of the fixing belt 101.

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 that provides mold releasability. Both ends of the shaft of the core 105a are rotatably supported by bearings on fixed parts (not shown). This pressure roller 105 is connected to a rotation drive device 107 such as a motor, and is driven to rotate during use.

In this way, with the outer surface of the fixing belt 101 regulated to 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 surface of the fixing belt 101, causing the toner image T on the recording material P to heat and pressurize, melt, and mix colors, and then cool, thereby fixing the toner image onto the recording material.

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 system that uses a ceramic heater 203 as a surface evaporative heating element. That is, the fixing device 200 includes a cylindrical fixing belt 101, a ceramic heater 203 that is a heat generating element, a rubbing member, and a heating element, 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 pressure roller 105.

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 using a screen printing method. The ceramic heater 203 is fitted into and fixed in a groove provided along the longitudinal direction (width direction perpendicular to the recording material conveyance direction) of the belt guide/heater holder 202, and is configured so that the inner surface of the fixing belt 101 rubs against the back surface of the substrate (the surface opposite the surface on which the resistance heating element is formed).

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

The fixing belt 101 is an endless belt whose cylindrical polyimide resin base is rotated in accordance with the rotation of the pressure roller 105 while its inner 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 direction of the rotation axis are rotatably supported on fixed parts (not shown), such as the frame of the fixing device 200.

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

The belt guide/heater holder 202 is molded from a heat-resistant, heat-insulating liquid crystal polymer or the like, and is arranged 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.

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.

In addition, both ends of the stay 204 are biased against the pressure roller 105 by a spring pressure mechanism (not shown) with a force of 16 kgf at one end, for a total pressure of 32 kgf. 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 the predetermined width required for toner fixing.

The pressure roller 105 is connected to a rotational drive device (not shown), and the fixing belt 101 rotates in response to the pressure roller 105, thereby nipping and transporting the recording material in the fixing nip 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) that serves as a temperature detection means and is 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).

In this way, with the surface of the fixing belt 101 regulated to 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 abutting the outer 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.

Another fixing device of this embodiment will be described with reference to FIG.
The fixing device 300 of this embodiment employs a fixing method using an IH (electromagnetic induction heating) heater as a heat source, and 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 between the fixing belt 101 and the pressure roller 105.

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

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

A semi-solid lubricant (grease) or oil composed 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 slidability between the rubbing member/pressure member 302 and the sliding layer on the inner surface of the fixing belt 101.

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 is, for example, the one described with reference to FIG.

In this way, with the surface of the fixing belt 101 regulated to 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 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.

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.

The fixing belt 101 in this disclosure is as shown in Figure 4. The fixing belt has a base layer 101d, an elastic layer 101c that covers the outer surface of the base layer, and a surface layer 101a that covers 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.

(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.

The outer surface of the base layer may be subjected to a surface treatment to provide adhesion to the elastic layer. Surface treatments can 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.

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 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, silicone polymer, hydrogenated methylsiloxane, alkoxysilane, reaction-accelerating catalyst, and colorant such as red iron oxide are appropriately blended and dispersed in an organic solvent. The primer can be selected appropriately depending on the material of the base layer, the type of elastic layer, and the form of crosslinking reaction. In particular, when the elastic layer contains a large amount of unsaturated aliphatic groups, a primer containing hydrosilyl groups is preferably used to impart adhesion through reaction with the unsaturated aliphatic groups. When the elastic layer contains a large amount of hydrosilyl groups, a primer containing unsaturated aliphatic groups is preferably used.

Other primers include those containing alkoxy groups. Commercially available primers can be used. Primer treatment involves applying the primer to the outer surface of the base layer (the surface that bonds to the elastic layer) and then drying or baking it.

(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.

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.

The elastic layer may contain a filler. The filler is added to control thermal conductivity, heat resistance, and elastic modulus. A tensile modulus of 0.5 N/ ^mm2 or more and 1.2 N/ ^mm2 or less is preferably used as a fixing member. If the tensile modulus is less than 0.5 N/ ^mm2 , the elastic layer becomes too soft, resulting in a shortened life at the edge of the paper. Furthermore, if the tensile modulus exceeds 1.2 N/ ^mm2 , 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.

Specific examples of the filler include non-conductive fillers such as 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), and titanium oxide (TiO ₂ ).

The material that makes up 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 alcohol, and hydroperoxides are used.

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).

As shown in Figure 5, if the elastic layer is simply heat-cured, the crosslink density of the elastic layer is low, so when grease, oil, adhesive, etc. adheres 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 crosslinking reaction with the base polymer, increasing the hardness of the elastic layer.

To prevent this, as shown in Figure 7, the elastic layer is irradiated with UV (702) from a UV (ultraviolet) lamp (701), activating the molecular chains and creating 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, these components are prevented from penetrating into the elastic layer, as shown in Figure 8. This prevents the elastic layer from expanding or hardening.

Also, because only the molecular chains on the surface exposed to UV light are activated, prolonged UV exposure can activate most of the molecular chains on the surface, preventing the cross-link density from increasing any further. Furthermore, 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 will react with the curing agent, preventing the cross-link density from increasing even with UV exposure.

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 can be promoted further and the crosslink density can be increased.
- The curing agent and adhesive used in producing 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.

(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: A sample is cut out, and its weight is measured and recorded. The sample is then immersed in dimethyl silicone oil having a kinematic viscosity of 10 m ² /s at 200°C for 12 hours at 25°C. After immersion, the dimethyl silicone oil adhering to the sample surface is removed and the weight is measured.
Evaluation method: The swelling degree (%) is calculated 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.

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

When the total length of the fixing belt in the longitudinal direction is W, the region from the center to each end up to W/3 is the central region B, and the regions closer to the ends than the central region B are the end regions A (see FIG. 9 ). Within 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 regions A1. Furthermore, when the swelling degree of the elastic layer in the central region B is QB [%], a region C showing a swelling degree QC [%] that satisfies the following formula 1 exists in the end region A1 with a width of 1 mm or more in the longitudinal direction.
QC<QB (Formula 1)
[In the formula, QC represents the degree of swelling (%) when the elastic layer in region C is immersed in dimethyl silicone oil having a kinematic viscosity of 10 m ² /s at 200°C at 25°C for 12 hours.]

By setting the swelling degree of the end regions of the elastic layer lower than that of the central region, it becomes more difficult for grease and oil components to penetrate from the ends, thereby preventing damage to the fixing belt.

The swelling degree QC preferably satisfies the following formula 2 in order to suppress swelling.
100≦QC≦110 (Formula 2)
If the QC is greater than 110%, grease and oil components will easily penetrate into the elastic layer. If the product is used for a long period of time in this state, the elastic layer will swell, causing a loss of strength and resulting in breakage.

On the other hand, it is preferable that the swelling degree QB in the central region B related to 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 a deterioration in image quality.If QB is more than 125%, the elastic layer becomes too soft and the life of the edge portion of the recording medium is shortened.

(3) Adhesive Layer The adhesive layer 101b is made of an addition-curing silicone rubber adhesive. This adhesive 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 crosslinking density on the surface is low, much of the uncrosslinked silicone rubber component in the adhesive will migrate into the elastic layer, reducing the adhesive function between the surface layer and the elastic layer.

(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.

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 this disclosure, the electrophotographic image forming apparatus is also simply referred to as a "printer."

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

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 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 the secondary transfer section by a pair of secondary transfer rollers 34 and transferred to 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 pressurizing the recording material P by a fixing unit 40.

[Example 1]
(Method for manufacturing 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.

(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.

(Step 2)
A filler-free, addition-curing liquid silicone rubber (product name: SE1886, manufactured by Dow Corning Toray Co., Ltd.) was prepared as the raw material for forming the elastic layer. This was a two-component type with a vinyl-containing organopolysiloxane as the base material and a hydrogen organopolysiloxane as the curing agent. 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 addition-curing silicone rubber composition, forming a 300 μm-thick elastic layer. The tensile modulus of this elastic layer was 1.2 N/ ^mm² .

(Step 3)
The substrate on which the elastic layer was formed was rotated in the circumferential direction at a moving speed of 20 mm/sec, and ultraviolet rays were irradiated onto the surface of the elastic layer in an atmospheric environment using an ultraviolet lamp positioned at a distance of 10 mm from the surface of the elastic layer.
A low-pressure mercury ultraviolet lamp (product name: GLQ500US/11, manufactured by Toshiba Lighting & Technology Corporation) was used as the ultraviolet lamp, and the irradiation time was set to 360 seconds so that the integrated light intensity at a wavelength of 185 nm on the irradiated surface was 800 mJ/ ^cm2 .

(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.

(Step 5)
A 20 μm fluororesin tube (Gunze Ltd., 959HP-PLUS) with a hydrophilic treated inner surface was placed over the belt, and excess adhesive was squeezed out from between the elastic layer and the fluororesin tube by uniformly squeezing the belt surface from above 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.

(Step 6)
The belt obtained in the previous process was covered with a metal thin film on the inner side of both ends 5 mm from each end, 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 metal thin 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.

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

[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. Except for this, the same method as in Example 1 was used to produce and evaluate the product.

[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 belt was manufactured and evaluated in the same manner as in Example 1.

[Comparative Example 1]
The same production method as in Example 1 was carried out except that step 6 in Example 1 was not carried out, and evaluation was carried out.

[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 manufacturing method as in Example 1 was used, and evaluation was carried out.

[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 and evaluated in the same manner as in Example 1.

[Comparative Example 4]
The amount of silicone rubber curing agent used in step 2 was reduced to adjust the tensile strength of the elastic layer to 0.4 N/ ^mm2 . The ultraviolet irradiation time in step 3 of Example 1 was changed to 600 seconds. Other than that, the same manufacturing method as in Example 1 was used, and evaluation was performed.

[Comparative Example 5]
The amount of the curing agent for the silicone rubber used in step 2 was increased to adjust the tensile strength of the elastic layer to 2.0 N/mm ^2. Except for this, the same method as in Example 1 was used to manufacture and evaluate the product.

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: dimethyl silicone oil having a kinematic viscosity of 10 m ² /s at a temperature of 200°C (manufactured by 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 by the following method. The sampled elastic layer was separated by 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.
Method for Separating the Elastic Layer 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 and the layer structure.
Second sample: The elastic layer in the end region A1 was separated from the fixing belt in the same manner as in 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 presence or absence of any sample that satisfies the requirements of Formula 1 is confirmed for the separately obtained QB. If the cut sample has a difference in swelling ratio in the horizontal direction, the cutting position is shifted to create a 1 mm wide sample with no variation in swelling ratio, and measurement is then performed.

(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 a method in accordance with 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 set 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 calculated 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 in the strain range of 0 to 10% was used.

Next, the evaluation method in this example will be described.
(Rating 1: Durability rating)
2 was installed in a modified digital commercial printing printer (product name: imageRUNNER ADVANCE C5560, manufactured by Canon Inc.), and evaluation was performed under the following evaluation conditions.
Test environment: room temperature 23 degrees, humidity 50%
Process speed: 200 mm/sec (s)
Printing speed: 30 sheets/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.
Every 100,000 sheets, the ends of the fixing belt and the paper edge on the outer circumferential surface of the fixing belt were observed to check for breakage of the elastic layer at the ends.
(Evaluation criteria)
Rank A: The elastic layer did not break after 400,000 or more sheets. Rank B: The elastic layer did not break after 300,000 or more sheets. Rank C: The elastic layer did not break after 200,000 or more sheets. Rank D: The elastic layer broke after less than 200,000 sheets.

(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 manufactured in the same manner as in the durability evaluation, and the fixing device shown in Figure 2, 10 sheets of evaluation images for melting unevenness are fixed consecutively under an environment of a temperature of 10°C and a relative humidity of 50%. The paper used is A4-sized recycled paper (product name: Recycled Paper GF-R100; manufactured by Canon Inc., thickness 92 μm, basis weight 66 g/ ^m2 , recycled paper content 70%, Beck smoothness 23 seconds (measured according to a method conforming to JIS P8119)). The evaluation image for melting unevenness is an image in which a 10 mm x 10 mm patch image formed with cyan toner and magenta toner at 100% concentration is placed near the center of the paper.
As a measure of 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 pressure is not applied to the concave areas of the paper texture, the toner grain boundaries remain after fixing, resulting in insufficient color mixing and uneven melting. If the fixing member cannot adequately conform to the texture, pressure is applied to the convex areas, causing color mixing, but in the concave areas, color mixing is insufficient. Therefore, the ability to conform to the texture was confirmed by observing the melting state of the image-forming area.
After printing images for evaluating uneven melting on 10 sheets in succession, a sample of the 10th sheet was taken out and the image-formed portion 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 portions of the paper fibers were mixed, and many toner grain boundaries were observed in the concave portions.

(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 Measuring Instrument MV-1000N; manufactured by Imada."
Test environment: room temperature 25°C, humidity 50%
Sample preparation method;
In step 1, as shown in Fig. 9 , when the total length of fixing belt 101 is W, a 10 mm-wide incision is made in the surface layer and elastic layer with a feather cutter in the circumferential direction of the fixing belt in a central region extending from the center of the fixing belt in the longitudinal direction to W/3 toward both ends (901). Next, a single incision is made parallel to the longitudinal direction of the fixing belt between the incisions (902). As step 2, from this incision, a new incision is made with the feather cutter at the interface between elastic layer 101c and fluororesin tube 101a at the end of the fixing belt, as shown in Fig. 10. Then, the 90-degree peeling strength of the interface between the elastic layer and the fluororesin tube was measured with a tester, 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 2.0 N/cm or more Rank B: Peeling strength is less than 2.0 N/cm

Table 1 shows the results of this example and the comparative example.
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.

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 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,
When the elastic layer of the central region B is immersed in dimethyl silicone oil having a kinematic viscosity of 10 m ² /s at 200°C for 12 hours at 25°C, 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)
[In the formula, QC represents the degree of swelling (%) when the elastic layer in region C is immersed in dimethyl silicone oil having a kinematic viscosity of 10 m ² /s at 200°C at 25°C for 12 hours.]
[Configuration 2]
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)
[Configuration 3]
3. The fixing belt according to claim 1, wherein a tensile modulus of elasticity measured using a 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.
[Configuration 4]
A fixing device comprising: the fixing belt according to any one of configurations 1 to 3; a pressing member disposed on an inner peripheral surface of the fixing belt and having a sliding surface that comes into contact with 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 pressing member and the fixing belt.
[Configuration 5]
5. The fixing device according to claim 4, wherein the pressing member is a heating member.

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 (5)

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,
When the elastic layer of the central region B is immersed in dimethyl silicone oil having a kinematic viscosity of 10 m ² /s at 200°C for 12 hours at 25°C, 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)
[In the formula, QC represents the degree of swelling (%) when the elastic layer in region C is immersed in dimethyl silicone oil having a kinematic viscosity of 10 m ² /s at 200°C at 25°C for 12 hours.] 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 fixing belt according to claim 1, wherein a tensile modulus of elasticity measured using a tensile test piece of the elastic layer sampled from the central region B is 0.5 N/mm< ^{2 >} or more and 1.2 N/mm< ² > or less. A fixing device comprising the fixing belt described in claim 1, 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 pressing member and the fixing belt. The fixing device of claim 4, wherein the pressing member is a heating member.