JP2008256839A - Fixing belt, fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing belt capable of maintaining stable heat generation characteristic for a long period of time by restraining degradation in the durability of a metal heat generation layer, and to provide a fixing device using the fixing belt and an image forming apparatus using the fixing device. <P>SOLUTION: The fixing belt includes a base layer, the metal heat generation layer and a metal protective layer in this order from the inner circumferential side, wherein the elastic modulus Eb(kgf/mm<SP>2</SP>) and thickness tb(mm) of the base layer, the elastic modulus Eh(kgf/mm<SP>2</SP>) and thickness th(mm) of the metal heat generation layer, and the elastic modulus Ep(kgf/mm<SP>2</SP>) and thickness tp(m) of the metal protective layer satisfy expressions (a) and (b). The fixing device includes the fixing belt, an electromagnetic induction heating means, pressure member and a pressing means. The image forming apparatus has the fixing device. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fixing belt, a fixing device using the fixing belt, and an image forming apparatus using the fixing device.

  Conventionally, in an image forming apparatus such as an electrophotographic copying machine or a printer, a process for fixing a toner image formed on a recording medium such as paper on the recording medium to form a permanent image is called a fixing process. Yes. In this fixing process, methods such as pressure fixing, oven fixing, solvent fixing, and thermal pressure fixing are conventionally used. However, among these methods, heat is effectively transmitted, and an unfixed toner image is strengthened. The thermal pressure fixing method is the most common because it is fixed on the surface and relatively safe.

  In the thermal pressure fixing method, a recording medium on which an unfixed toner image is formed is passed through a contact area constituted by two heated rolls or belts, and is heated by the rolls or belts to be in a molten state. In this method, the formed unfixed toner image is fixed on the surface of the recording medium by being pressed against the recording medium by the pressure applied to the contact area. At this time, in order to transmit heat to the unfixed toner image, the fixing member (roll or belt) is heated by heating means such as a halogen heater.

In recent years, an electromagnetic induction heating method has been studied as a method for heating the fixing member. This electromagnetic induction heating method uses a coil in addition to a fixing member and a pressure member in a fixing device (induction heating fixing device) using this electromagnetic induction heating method. This coil is installed in the fixing member or at a position close to the external fixing member, and is electrically connected to a high-frequency power source. When a high-frequency alternating current is passed through the coil by a high-frequency power source, a magnetic flux is generated in a direction perpendicular to the surface around which the coil is wound, depending on the direction of the current. This magnetic flux crosses the metal heat generating layer of the fixing member installed in the vicinity of the coil, and an eddy current is generated in the metal heat generating layer of the fixing member so as to generate a magnetic field in the direction to cancel the magnetic flux. Since the metal heat generating layer has a resistance value determined by the metal material constituting the layer and the thickness of the layer, the electric energy generated by the generated eddy current is converted into heat energy.
As a result, the surface of the fixing member is heated by the heat generated by the metal heat generating layer. Therefore, when the recording medium on which the unfixed toner image is formed passes through the contact area between the fixing member and the pressure member, the unfixed toner image is recorded. The medium is heat-pressed and fixed.

By using the above-described electromagnetic induction heating method, the surface of the fixing member to be heated can be heated effectively and with high thermal efficiency, so the time until fixing is possible (hereinafter referred to as “warm-up time”) There is a possibility that it can be shortened.
As a fixing member applied to this electromagnetic induction heating method, for example, an endless fixing belt having a structure in which a metal heating layer is provided on a base material made of a heat-resistant resin such as engineering plastic can be cited. Since the fixing belt of this configuration is secured by a base material made of a heat-resistant resin, the metal heating layer can be made thin if the heat generation performance can be sufficiently ensured, and the warm-up can be performed. Time can be shortened. Further, since the base material is made of a heat resistant resin, the slidability with the pressing member provided on the inner surface of the fixing belt is also good.

In a fixing device or an image forming apparatus in which an endless fixing belt as described above is used, the fixing belt is bent between the fixing belt and a pressure member pressed against the fixing belt by bending the fixing belt with a large curvature. Since the recorded recording medium is discharged in a direction away from the fixing belt due to its own rigidity, the recording medium can be peeled off from the endless belt.
However, when the metal heating layer is provided on the endless fixing belt as described above, the fixing belt is distorted by bending deformation by bending the fixing belt with a large curvature. In particular, when the fixing belt is driven around and the metal heating layer of the fixing belt is repeatedly distorted, the metal heating layer may be cracked or permanently deformed due to fatigue. When cracks occur in the metal heat generating layer, the conductivity of the metal heat generating layer is remarkably reduced and heat generation is not effectively performed by electromagnetic induction heating. Therefore, the life of the fixing belt may be shortened due to fatigue of the metal heating layer.

As a means to prevent cracking and permanent deformation of the metal heat generating layer, a polyimide resin is used as a heat-resistant resin constituting the substrate, and the substrate is formed by controlling the imidization ratio of the polyimide resin when forming the substrate. There has been proposed a technique for imparting flexibility and reducing mechanical stress on a metal heat generating layer provided on the base material (see, for example, Patent Document 1).
Patent Documents 2 and 3 propose a technique in which a protective layer made of a synthetic resin or the like is provided on both sides of a metal heat generation layer, and deformation that occurs in the metal heat generation layer when the belt is bent is proposed.
Furthermore, Patent Document 4 proposes to provide a metal protective layer by electrolytic nickel plating instead of the protective layer made of synthetic resin.
However, the present state of technology has not yet fully solved the shortage of durability of the metal heating layer.
JP 2001-341231 A JP 2004-70191 A JP 2004-133370 A JP 2006-71998 A

An object of the present invention is to solve the following problems.
That is, the present invention provides a fixing belt capable of improving durability of a metal heat generating layer and maintaining stable heat generation characteristics over a long period of time, a fixing device using the same, and an image forming apparatus using the fixing device. This is the issue.

The above object is achieved by the present invention described below. That is, the present invention
<1> A base layer, a metal heating layer, and a metal protective layer are provided in this order from the inner peripheral side,
Elastic modulus Eb (kgf / mm ² ), thickness tb (mm) of the base layer, elastic modulus Eh (kgf / mm ² ), thickness th (mm) of the metal heating layer, elastic modulus Ep of the metal protective layer The fixing belt is characterized in that (kgf / mm ² ) and thickness tp (mm) satisfy the following expressions (a) and (b).

  <2> The fixing belt according to <1>, wherein the metal protective layer contains a metal mainly composed of nickel.

<3> The fixing belt according to <1> or <2>, wherein the metal protective layer contains a nickel composite.

  <4> The fixing belt according to any one of <1> to <3>, wherein the metal protective layer contains a nickel composite and is formed by an electroless plating method.

  <5> The fixing belt according to <3> or <4>, wherein the nickel composite is a nickel-phosphorus alloy.

  <6> The fixing belt according to <5>, wherein the content of phosphorus in the nickel-phosphorus alloy is 1 to 12% by mass.

  <7> The fixing belt according to <3> or <4>, wherein the nickel composite is a nickel-boron alloy.

  <8> The fixing belt according to <7>, wherein a content of boron in the nickel-boron alloy is 0.1 to 6% by mass.

  <9> The fixing belt according to <3> or <4>, wherein the nickel composite is a nickel-silicon carbide composite.

  <10> The fixing belt according to <9>, wherein the content of silicon carbide in the nickel-silicon carbide composite is 1 to 15% by mass.

<11> A fixing belt having a metal heating layer rotatably arranged, and an electromagnetic induction heating means that is arranged at a position facing the outer peripheral surface of the fixing belt and generates a magnetic field to heat the metal heating layer. A recording medium is sandwiched and conveyed by the fixing belt, and a pressure member that heats and fixes an unfixed toner image on the recording medium is disposed in contact with an inner peripheral surface of the fixing belt, and is directed toward the pressure member. And a pressing member that presses the fixing belt.
The fixing device is the fixing belt according to any one of <1> to <10>.

<12> An image carrier, a charging unit for charging the surface of the image carrier, a latent image forming unit for forming a latent image on the charged surface of the image carrier, and developing the latent image with toner to be determined A developing unit that forms a contact toner image, a transfer unit that transfers the unfixed toner image onto a recording medium, and a fixing unit that heat-fixes the unfixed toner image onto the recording medium.
An image forming apparatus, wherein the fixing unit is the fixing device according to <11>.

  As described above, according to the present invention, the durability of the metal heating layer is excellent and stable over a long period of time compared to the fixing belt that does not consider the elastic modulus and thickness of the base layer, the metal heating layer, and the metal protective layer. It is possible to provide a fixing belt that can maintain the heat generation characteristics, a fixing device using the fixing belt, and an image forming apparatus using the fixing device.

<Fixing belt>
The fixing belt of the present invention has a base layer, a metal heating layer, and a metal protective layer in this order from the inner peripheral side, and has an elastic modulus Eb (kgf / mm ² ), a thickness tb (mm) of the base layer, The elastic modulus Eh (kgf / mm ² ) and thickness th (mm) of the metal heating layer, and the elastic modulus Ep (kgf / mm ² ) and thickness tp (mm) of the metal protective layer are expressed by the following formula (a). And the expression (b) is satisfied.

As in the present invention, a fixing belt having a metal heat generating layer and a metal protective layer may be deformed when bent depending on the elastic modulus and thickness of the metal protective layer provided to suppress deformation of the metal heat generating layer. As a result, strain on the surface of the protective layer is increased, and as a result, cracks are generated from the surface of the metal protective layer, which propagates to the metal heating layer, resulting in insufficient durability.
In addition, when the pressure roll is brought into contact with the fixing belt and driven to rotate, it is preferable that the pressure roll has a flare shape in order to prevent paper wrinkles. However, the flare shape of the pressure roll causes the fixing belt to twist. Stress is generated. Further, when continuously fixing a sheet having a small width, the temperature of the non-sheet passing portion rises, and the outer diameter of the non-sheet passing portion of the pressure roll increases due to thermal expansion of the pressure roll. Stress that twists is generated.
In addition, when the belt is directly driven, there are a method in which the belt is stretched on a plurality of stretching rolls and one of the stretching rolls is rotationally driven, and a method in which a gear is provided at the end of the belt to drive the belt. However, from the viewpoint of energy saving, the number of members in contact with the belt is preferably as small as possible, so the latter method is preferable. However, since a driving force is transmitted from the belt end, a large torsional stress is generated on the belt.
As described above, when a stress that twists the fixing belt is generated, the metal heat generating layer and the metal protective layer overlap with the distortion caused by the above-described bending, and the distortion caused by the twisting and the cracking occur. There was a shortage.

Since the fixing belt of the present invention satisfies the above-mentioned formula (a), the distortion of the metal heating layer during bending can be suppressed and the distortion of the metal protective layer can be reduced, so that sufficient bending durability can be obtained. Further, by satisfying the formula (b), even when an external stress that twists the fixing belt is generated, distortion of the metal heat generating layer and the metal protective layer can be suppressed, so that more excellent durability can be obtained.
As a result, the fixing belt of the present invention can maintain stable heat generation characteristics over a long period of time.

  In particular, in the present invention, the metal protective layer preferably contains a nickel composite. In this case, even if it is a thin layer, it becomes a metal protective layer having high strength and excellent durability, and it is possible to effectively suppress a decrease in durability due to cracking of the metal heating layer.

[Configuration of fixing belt]
The fixing belt of the present invention is not particularly limited as long as it has a base layer, a metal heating layer, and a metal protective layer in order from the inner peripheral side, and is preferably an endless belt.
In order to prevent an unfixed toner image from adhering to the outer peripheral surface of the fixing belt during fixing, it is preferable to provide a release layer on the surface of the metal protective layer. Further, an elastic layer may be provided between the metal protective layer and the release layer in order to improve the color image quality and improve the black-and-white image formation speed.

Hereinafter, with reference to FIG. 1, a configuration example of the fixing belt of the present invention is shown, but the present invention is not limited to this. Here, FIG. 1 is a schematic cross-sectional view showing a configuration example of the fixing belt of the present invention.
The fixing belt 10 shown in FIG. 1 has a metal heating layer 10b that self-heats by electromagnetic induction, a metal protective layer 10c, an elastic layer 10d, and a release layer 10e in this order on the outer peripheral surface of the base layer 10a. An endless belt having a layer structure formed.
In the fixing belt 10, the layers are preferably laminated so that the metal heating layer 10 b is in the vicinity of the neutral axis of the fixing belt 10. Here, the “neutral axis of the fixing belt 10” is a line of intersection between a surface where no distortion occurs when the fixing belt 10 is bent and a cross section of the fixing belt 10, and the thickness and elastic modulus of each layer. And is determined by
Below, each layer which comprises the fixing belt of this invention is demonstrated in detail.

[Base layer]
The base layer in the fixing belt of the present invention is required to maintain high strength without deterioration in physical properties even when the adjacent metal heating layer is heated. For this reason, the base layer is mainly composed of a heat-resistant resin. (In this specification, “mainly” and “main component” mean that the mass ratio is 50% or more, and the following is also synonymous. Is).
In the case of a base layer mainly composed of a heat-resistant resin, it is possible to ensure slidability with the pressing member in contact with the inner peripheral surface of the fixing belt, and to extend the life of the pressing member. Furthermore, since the heat resistant resin has a heat insulating effect, it is possible to efficiently use the heat generated in the metal heat generating layer without releasing it to the pressing member.

Examples of the heat-resistant resin that can form the base layer include high heat-resistant and high-strength resins such as liquid crystal materials such as polyimide, aromatic polyamide, and thermotropic liquid crystal polymer. In addition to these, polyester, polyethylene terephthalate, poly Ether sulfone, polyether ketone, polysulfone, polyimide amide and the like are used. Among these, polyimide is preferable.
Moreover, you may further improve a heat insulation effect by adding the filler with a heat insulation effect in a heat resistant resin, or making a heat resistant resin foam.

The thickness tb of the base layer is preferably in the range of 10 to 100 μm, and more preferably in the range of 30 μm to 80 μm, from the viewpoint of achieving both rigidity and flexibility that enable repeated circumferential conveyance of the fixing belt over a long period.
If the thickness of the base layer is less than 10 μm, the rigidity is weak and wrinkles may occur or cracks may occur at both ends. On the other hand, if the thickness of the base layer exceeds 100 μm, flexibility may not be ensured, and the heat capacity may increase, so the warm-up time may be long.

In addition, the elastic modulus Eb of the base layer is preferably in the range of 100 to 3000 kgf / mm ² from the viewpoint of achieving both rigidity and flexibility that enable repeated circumferential conveyance over a long period of time, and 200 to 2000 kgf / mm ^2. A range of mm ² is more preferred.

[Metal heating layer]
In the fixing belt of the present invention, the metal heat generating layer is a heat generating layer having a function of generating heat due to an eddy current generated in this layer when a magnetic field is applied, and is configured using a metal that generates electromagnetic induction. The
As a metal that generates an electromagnetic induction effect, for example, a single metal such as nickel, iron, copper, gold, silver, aluminum, chromium, tin, or zinc, or two or more alloys can be selected. Among these, copper, gold, silver and alloys thereof are preferable from the viewpoint of low specific resistance and sufficient heat generation, and copper or copper-based alloy is particularly preferable from the viewpoint of cost and workability. .

The thickness th of the metal heat generating layer is preferably thin from the viewpoint of heat capacity. However, if the thickness is less than 1 μm, the resistance value increases, so that it becomes difficult to generate sufficient eddy currents and heat generation is insufficient. In some cases, the time becomes longer, or it becomes impossible to heat to a fixable temperature. On the other hand, when the thickness of the metal heat generating layer exceeds 50 μm, eddy current is generated, but the resistance value is too low, so that heat generation is insufficient and the warm-up time may be long. In addition, the heat-up time of the metal heat generating layer itself may be increased due to an increase in the heat capacity.
Therefore, the thickness th of the metal heating layer is preferably in the range of 1 to 50 μm, more preferably in the range of 3 to 20 μm, and still more preferably in the range of 5 to 15 μm.

In addition, the elastic modulus Eh of the metal heat generating layer is preferably in the range of 1000 to 25000 kgf / mm ² from the viewpoint of achieving both rigidity and flexibility that enables repeated circumferential conveyance of the fixing belt over a long period, and is preferably 1500 to 2500 kgf / mm ^2. The range of 15000 kgf / mm ² is more preferable.

[Metal protective layer]
In the present invention, the metal protective layer preferably contains a nickel composite.
Here, the nickel composite in the present invention includes a nickel alloy and a composite of nickel and an inorganic compound, and excludes nickel alone.
Examples of nickel alloys include nickel containing one or more elements selected from phosphorus, boron, tungsten, cobalt, chromium, copper, and the like. In particular, a nickel-phosphorus alloy and a nickel-boron alloy are preferable because they are excellent in hardness and can be thinned.
Examples of the composite of nickel and an inorganic compound include nickel containing one or more inorganic compounds selected from silicon carbide, boron carbide, boron nitride, silica, alumina, zirconia, and the like. Nickel-silicon carbide composites are preferable because they are excellent in hardness and can be thinned.

When a nickel-phosphorus alloy suitable as the nickel composite in the present invention is used, an amorphous film is formed, and thus a tough metal protective layer can be formed. In addition, since a high resistance film is formed, there is little reduction in efficiency during dielectric heating.
In particular, a nickel-phosphorus alloy can form a metal protective layer having a high elastic modulus with a uniform film thickness and a Vickers hardness of about 500 HV by using an electroless plating method. As a result, the metal protective layer can be thinned.
The phosphorus content in the nickel-phosphorus alloy is preferably 1 to 12% by mass. When the phosphorus content is less than 1% by mass, the effect of improving the elastic modulus is reduced, and when it exceeds 12% by mass, the heat resistance is deteriorated.
Moreover, it is a preferable aspect that the content of phosphorus in the nickel-phosphorus alloy is 6 to 12% by mass from the viewpoint that a nonmagnetic film is formed and the efficiency reduction of induction heating can be further reduced.

The nickel-boron alloy suitable as the nickel composite in the present invention is to form a metal protective layer having a high elastic modulus with a uniform film thickness and a Vickers hardness of 700 to 800 HV, particularly by using an electroless plating method. Can do. As a result, the metal protective layer can be thinned.
The boron content in the nickel-boron alloy is preferably 0.1 to 6% by mass. When the boron content is less than 0.1% by mass, the effect of improving hardness and elastic modulus is reduced, and when it exceeds 6% by mass, it is difficult to form a layer by an electroless plating method. .
Moreover, it is a preferable aspect that content of the boron in a nickel-boron alloy is 3-6 mass% from a viewpoint that an amorphous film is formed and a tough metal protective layer is formed.

On the other hand, the nickel-silicon carbide composite suitable as the nickel composite in the present invention is a metal protective layer having a high elastic modulus with a uniform film thickness and a Vickers hardness of 500 HV or more, particularly by using an electroless plating method. Can be formed. As a result, the metal protective layer can be thinned.
The silicon carbide content in the nickel-silicon carbide composite is preferably 1 to 15% by mass. When the content of silicon carbide is less than 1% by mass, the effect of improving hardness and elastic modulus is reduced, and when it exceeds 15% by mass, the surface state becomes rough and it is difficult to form a good metal protective layer. It becomes.

In the present invention, whether the metal protective layer is amorphous or nonmagnetic can be confirmed by the following method.
That is, X-ray diffraction (XRD) measurement is performed with an X-ray diffractometer (manufactured by Rigaku Corporation), and it is determined that the material is amorphous by not showing a clear peak.
Moreover, it measures using a low magnetic permeability meter (made by an electronic magnetic industry Co., Ltd.), and it is judged that it is nonmagnetic because a magnetic permeability is 1.3 or less.

  Moreover, the measurement of the composition of the nickel composite which comprises a metal protective layer is performed by performing a composition analysis with a fluorescent X ray analyzer (made by Rigaku Corporation).

  As described above, the metal protective layer using a nickel-phosphorus alloy, a nickel-boron alloy, or a nickel-silicon carbide composite is preferably formed by an electroless plating method in order to increase the hardness. A known plating method is applied to the electroless plating method. Moreover, the composition (mass ratio of nickel and other components) of the metal protective layer to be formed can be adjusted by adjusting the composition of the plating solution.

In the present invention, a metal protective layer having excellent hardness can be formed by using a nickel composite as described above. Therefore, the thickness of the metal protective layer can be reduced. As a result, the distortion of the metal surface at the time of bending can be reduced, the occurrence of cracks and the like can be suppressed, and the durability of the metal protective layer can be increased.
Moreover, when forming the metal protective layer which consists of a nickel composite using an electroless-plating method, in addition to being excellent in strength, since a metal protective layer with few defects is formed, reliability can also be improved.

  The thickness tp of the metal protective layer is preferably in the range of 1 to 40 μm, and more preferably in the range of 2 to 30 μm, from the viewpoint of achieving both rigidity and flexibility that enable repeated circumferential conveyance over the fixing belt. preferable.

In addition, the elastic modulus Ep of the metal protective layer is preferably in the range of 2000 to 30000 kgf / mm ² from the viewpoint of achieving both rigidity and flexibility that enable repeated circumferential conveyance of the fixing belt over a long period. The range of 20000 kgf / mm ² is more preferable.

Here, a method for measuring the elastic modulus of the base layer, the metal heating layer, and the metal protective layer in the present invention will be described.
First, a thin film sample of each layer was cut into the shape of a dumbbell No. 3 test piece, and this was subjected to a tensile test at 10 mm / min in an autograph with an oven (manufactured by Shimadzu Corporation) under an environment of 170 ° C. The elastic modulus was measured from the obtained stress-strain curve. Samples of the metal heating layer and the metal protective layer were obtained by peeling the base layer from those formed on the base layer.

Moreover, the measurement of the film thickness of each layer is performed as follows.
That is, the film thickness of the base layer was measured with an eddy current film thickness meter (manufactured by Fisher Instruments Co., Ltd.). Moreover, the film thickness of the metal heat generating layer and the metal protective layer was measured with a fluorescent X-ray film thickness meter (manufactured by Fisher Instruments Co., Ltd.).

[Release layer]
The fixing belt of the present invention is mainly composed of a low surface energy material such as a fluorine-based compound in order to prevent an unfixed toner image in a molten state from adhering to the surface (outer peripheral surface) on the side in contact with the recording medium. It is preferable to have a release layer which is
Examples of the fluorine compound used in the release layer include fluororubber, polytetrafluoroethylene (hereinafter referred to as “PTFE”), perfluoroalkyl vinyl ether copolymer (hereinafter referred to as “PFA”), tetrafluoride, and the like. A fluororesin such as an ethylene hexafluoropropylene copolymer (hereinafter referred to as “FEP”) can be used, but is not particularly limited.

The thickness of the release layer is preferably in the range of 1 to 100 μm, more preferably in the range of 10 to 50 μm, and still more preferably in the range of 20 to 50 μm.
If the thickness of the release layer is less than 1 μm, the release layer may be worn away by repeated rubbing at the edge of the recording medium. On the other hand, when the thickness of the release layer exceeds 100 μm, the flexibility of the surface is lost, and as a result, the force of crushing the toner works and the granularity of the fixed image may be impaired. In addition, since the heat capacity is increased, the warm-up time may be increased.
Since the material forming the release layer has a low elastic modulus and a thin film thickness, even if the release layer is provided, the position of the neutral axis of the fixing belt and the expressions (a) and (b) are not affected. do not do.

[Elastic layer]
In the fixing belt of the present invention, an elastic layer may be further provided between the metal protective layer and the release layer. In particular, when forming a color image, it is preferable to provide an elastic layer. In the present invention, the term “elastic layer” means a layer composed of a material that can be restored to its original shape even when deformed by applying an external force of 100 Pa. Is also synonymous.
This elastic layer follows the unevenness of the toner image on the recording medium, and the surface of the fixing belt is in close contact with the toner image. Therefore, particularly when forming a color image, the heating unevenness of the recording medium and the toner image is small, and the glossy An image with little unevenness is obtained.
Even when a black and white image is formed, it is particularly preferable to provide an elastic layer in order to cope with a higher speed. By providing an elastic layer, the elastic layer is deformed in the contact area with the pressure member, and a sufficient contact width can be obtained even with a low load. Therefore, heat can be transferred to the toner image even at high speed. This is because fixing is possible.
Since elastic materials such as sponge and rubber have a low elastic modulus, even if an elastic layer is provided, the position of the neutral axis of the fixing belt and the above expressions (a) and (b) are not significantly affected.

In addition, as a material which comprises an elastic layer, a well-known elastic material can be used.
As the elastic material, for example, heat-resistant rubber such as silicone rubber or fluoro rubber is preferably used.
Examples of the heat-resistant rubber include liquid silicone rubber SE6744 manufactured by Toray Dow Corning Silicone, Viton B-202 manufactured by DuPont Dow elastmers.

-Manufacturing method of fixing belt-
As a method for producing the fixing belt of the present invention, a known method can be used. In addition, since the metal heat generating layer and the metal protective layer are thin and it is difficult to handle these layers alone, it is preferable to form the metal heat generating layer and the metal protective layer in this order on the base layer. Moreover, an elastic layer and a mold release layer can be formed on a metal protective layer as needed.

  When forming a release layer or an elastic layer and a release layer on the metal protective layer by a coating method, the surface of the metal protective layer or the elastic layer is formed before coating and forming these layers. It is preferable to perform pretreatment with an appropriate primer material as necessary. By performing this pretreatment, the adhesion between the layers can be further improved.

When a release layer or an elastic layer and a release layer are laminated on the metal protective layer by a coating method, the release layer and the elastic layer are subjected to a process of heat-treating the coated film. A layer is formed.
The heat treatment of the coating film may be performed in an inert gas (nitrogen gas, argon gas, etc.) atmosphere.

<Fixing device and image forming apparatus>
Next, the fixing device of the present invention and the image forming apparatus of the present invention will be described.

[Fixing device]
As long as the fixing device of the present invention can include the above-described fixing belt of the present invention as a fixing member, the configuration of a known electromagnetic induction heating type fixing device (electromagnetic induction heating fixing device) can be applied. .

The fixing device using the fixing belt of the present invention preferably has the following configuration.
That is, the fixing device of the present invention is disposed in a rotatable manner, the fixing belt of the present invention, and a position facing the outer peripheral surface of the fixing belt, and generates electromagnetic fields to heat the metal heating layer. A pressure member that sandwiches and conveys the recording medium between the induction heating means and the fixing belt, heats and fixes the unfixed toner image on the recording medium, and is disposed in contact with the inner peripheral surface of the fixing belt; And a pressing member that presses the fixing belt toward the pressing member.
The fixing in this fixing device is performed by inserting the recording medium on which the unfixed toner image is formed into contact with the fixing belt heated with the unfixed toner image and passing through the area where the fixing belt and the pressure member are in contact with each other. Is done. In other words, when the recording medium on which the unfixed toner image is formed is nipped and conveyed between the contact area between the fixing belt and the pressure member, the unfixed toner image is pressed in a molten state and is applied to the surface of the recording medium. It is fixed.

Next, an exemplary embodiment of the fixing device of the present invention will be described in more detail with reference to the drawings.
FIG. 2 is a schematic cross-sectional view showing an exemplary embodiment of an electromagnetic induction heating type fixing device 100 using the fixing belt of the present invention.
In FIG. 2, reference numeral 10 denotes an endless fixing belt having the layer structure shown in FIG. 1, which is the fixing belt of the present invention.
As shown in FIG. 2, the fixing device 100 is provided with a pressure roll (pressure member) 11 so as to be in contact with the outer peripheral surface of the fixing belt 10. A contact area between the two is formed. In this contact region, the fixing belt 10 is curved in a shape along the peripheral surface of the pressure roll 11.
Here, the pressure roll 11 has a configuration in which an elastic layer 11b made of silicone rubber or the like is formed on a base material 11a, and a release layer 11c made of a fluorine compound or the like is further formed thereon.

In addition, the fixing device 100 is provided with a pressing member 13 that contacts the inner peripheral surface of the fixing belt 10 and presses the inner peripheral surface of the fixing belt 10 toward the pressure roll 11. By this pressing member 13, the pressure applied to the contact area between the fixing belt 10 and the pressure roll 11 can be locally increased.
The pressing member 13 includes a pad 13b made of metal, heat-resistant resin, heat-resistant rubber, or the like that is in contact with and presses against the inner peripheral surface of the fixing belt 10, and a support 13a that supports the pad 13b.

Further, the fixing device 100 includes an electromagnetic induction device (electromagnetic induction) including an electromagnetic induction coil (excitation coil) 12 a at a position outside the fixing belt 10 and facing the pressure roll 11 with the fixing belt 10 as the center. (Heating means) 12 is provided. The electromagnetic induction device 12 applies an alternating current to the electromagnetic induction coil 12 a to change a generated magnetic field by an excitation circuit and generate an eddy current in the metal heating layer of the fixing belt 10. This eddy current is converted into heat (Joule heat) by the electric resistance of the metal heating layer, and as a result, the surface of the fixing belt 10 generates heat.
Note that the installation position of the electromagnetic induction device 12 is not particularly limited as long as the metal heating layer of the fixing belt 10 can generate heat.

Hereinafter, the heat generation principle of the metal heat generating layer 10b by the electromagnetic induction action in the fixing device 100 shown in FIG. 2 will be described below.
First, when an alternating current is applied to the electromagnetic induction coil 12a by an unillustrated excitation circuit, the magnetic flux repeatedly generates and disappears around the electromagnetic induction coil 12a. When this magnetic flux crosses the metal heating layer 10b of the fixing belt 10, an eddy current is generated in the metal heating layer 10b so as to generate a magnetic field that hinders the change of the magnetic flux. Joule heat is generated by the eddy current and the specific resistance of the metal heating layer 10b.

Due to the skin effect, the eddy current generated in the metal heating layer 10b flows almost concentrated on the surface of the metal heating layer 10b on the side of the electromagnetic induction device 12, and generates heat with power proportional to the skin resistance Rs of the metal heating layer 10b. Produce.
Here, when the angular frequency is ω, the magnetic permeability is μ, and the specific resistance is ρ, the skin depth δ is expressed by the following equation (1).
Formula (1) δ = (2ρ / ωμ) ^1/2

The skin resistance Rs is expressed by the following formula (2).
Formula (2) Rs = ρ / δ = (ωμρ / 2) ^1/2

Further, the electric power P generated in the metal heat generating layer 10b of the fixing belt 10 is expressed by the following formula (3), where Ih is a current flowing through the fixing belt 10.
Formula (3) P∝Rs∫ | Ih | 2dS

Therefore, if the skin resistance Rs is increased or the current Ih is increased, the power P can be increased and the amount of heat generated can be increased. Here, the skin depth δ (m) is expressed by the following expression (4) by the frequency f (Hz) of the excitation circuit, the relative permeability μr, and the specific resistance ρ (Ω · m).
Formula (4) δ = 503 (ρ / (fμr)) ^1/2

This indicates the depth of absorption of electromagnetic waves used in electromagnetic induction, and the intensity of electromagnetic waves is 1 / e or less deeper than this, and conversely most energy is absorbed to this depth. Yes.
Here, the thickness of the metal heating layer 10b is preferably thicker (3 to 100 μm) than the skin depth represented by the above formula. This is because if the thickness of the metal heating layer 16b is smaller than 3 μm, most of the electromagnetic energy cannot be absorbed and the efficiency may deteriorate.

Next, fixing by the electromagnetic induction heating type fixing device 100 shown in FIG. 2 will be described.
First, the pressure roll 11 is rotated in the direction of arrow C by a driving device (not shown), and the fixing belt 10 is also rotated in the direction of arrow B accordingly. Here, the recording medium 15 on which the unfixed toner image 14 is formed is nipped and conveyed in the direction of the arrow A in the contact area between the fixing belt 10 and the pressure roll 11 that have generated heat by the heat generation mechanism as described above. At this time, in the contact area between the fixing belt 10 and the pressure roll 11, the unfixed toner image 14 is pressed against the surface of the recording medium 15 in a molten state and fixed on the surface of the recording medium 15.
Here, in the vicinity of the exit of the contact area between the fixing belt 10 and the pressure roll 11, the fixing belt 10 is released from being pressed by the pressure member 13 and bent toward the base layer with a large curvature, so that the shape of the fixing belt 10 is changed. It changes rapidly. On the other hand, when the recording medium 15 is fed into the contact area between the fixing belt 10 and the pressure roll 11, it advances along the peripheral surface of the pressure roll 11. For this reason, the recording medium 15 is peeled off from the fixing belt 10 by its own rigidity, and self-stripping becomes possible. As described above, the radius of curvature when the fixing belt 10 is largely bent is about 5 mm.

  Here, the pressure roll 11 is driven and the fixing belt 10 is driven. However, a driving method in which the fixing belt 10 is driven and the pressure roll 11 is driven may be applied. In that case, by driving the fixing belt 10, it is possible to warm up the pressure roll in a non-contact state, and only the belt having a small heat capacity is heated, so that the warm up time can be significantly shortened. Further, since the feedback control for canceling the change in the sheet passing speed due to the thermal expansion of the pressure roll, which is necessary when the pressure roll is driven, becomes unnecessary, the belt drive is preferable.

  Since the fixing device of the present invention has the fixing belt of the present invention whose heat generation characteristics do not deteriorate even when used for a long period of time, it is possible to perform fixing stably and save energy because less standby power is required. is there.

[Image forming apparatus]
Next, an image forming apparatus using the fixing device of the present invention will be described. The image forming apparatus of the present invention is not particularly limited as long as it uses the fixing device of the present invention as a fixing device in a known image forming apparatus using an electrophotographic method, but may have the following configuration. preferable.
That is, the image forming apparatus of the present invention includes an image carrier, a charging unit that charges the surface of the image carrier, a latent image forming unit that forms a latent image on the charged surface of the image carrier, and the latent image. Is developed with a developer to form an unfixed toner image, a transfer unit that transfers the unfixed toner image to a transfer medium, and a fixing unit that heat-fixes the unfixed toner image on a recording medium (present invention). And a fixing device). Moreover, you may equip other well-known mechanisms and members as needed.

Hereinafter, an exemplary embodiment of the image forming apparatus of the present invention will be described with reference to the drawings. Here, FIG. 3 is a schematic diagram showing a configuration example of the image forming apparatus of the present invention including the fixing device 100 shown in FIG.
3 includes a photosensitive drum (image holding member) 202, a charging device (charging unit) 204, a laser scanner (latent image forming unit) 206, a mirror 208, a developing device (developing unit) 210, An intermediate transfer body 212, a transfer roll (transfer means) 214, a cleaning device 216, a charge removal device 218, a developing device (developing means) 100, a paper feed unit 220, a paper feed roller 222, a registration roller 224, and a recording medium guide 226 are provided. Prepare.

  In FIG. 3, a charging device 204 that is provided in the vicinity of the photosensitive drum 202 in order in the direction of the arrow along the periphery of the photosensitive drum 202 and charges the surface thereof (non-contact type), and the surface of the photosensitive drum 202 A rotary developing device 210 that forms a toner image by applying toner to the latent image formed on the surface, and the outer peripheral surface contacts the surface of the photosensitive drum 202 and can rotate in both the arrow D direction and the arrow E direction. An intermediate transfer body 212, a cleaning device 216 that cleans the surface of the photosensitive drum 202 after the toner image is transferred to the surface of the intermediate transfer body 212, and a static elimination device 218 that neutralizes the surface of the photosensitive drum 202 are provided. .

  In addition, on the surface of the photosensitive drum 202 between the charging device 204 and the developing device 210, in order to form a latent image on the surface of the photosensitive drum 202, laser light corresponding to the image information (signal) of each color is mirrored. Irradiated from the laser scanner 206 via 208.

  The developing device 210 is provided with developing devices (not shown) for the respective colors respectively containing toners of four colors, cyan, magenta, yellow, and black. The developing device 210 rotates in the direction of the arrow, thereby causing the photosensitive drum 202 to rotate. A toner image can be formed by applying toner of each color to the latent image formed on the surface of the toner.

  In addition to the photosensitive drum 202, a transfer roll 214 is provided around the intermediate transfer body 212. The outer peripheral surface of the intermediate transfer body 212 and the surface of the transfer roll 214 are in pressure contact, and the recording medium can be inserted through the pressure contact portion in the direction of arrow A. When the recording medium passes through the pressure contact portion, the surface of the intermediate transfer body 212 The toner image held on the recording medium is transferred to the surface of the recording medium. Further, a sheet feeding device is provided on the opposite side to the direction of the arrow A with respect to the press contact portion, and a fixing device 100 is provided on the side of the arrow A direction.

  The sheet feeding device includes a sheet feeding unit 220, a sheet feeding roller 222, a registration roller 224, and a recording medium guide 226. Paper feeding to the pressure contact portion between the intermediate transfer member 212 and the photosensitive drum 202 is performed by feeding a recording medium stored in the paper feeding unit 220 by a recording medium push-up means (not shown) built in the paper feeding unit 220. When the recording medium comes into contact with the sheet feeding roller 222, the sheet feeding roller 222 and the registration roller 224 rotate and are conveyed in the direction of arrow A along the recording medium guide 226. Is done.

  The fixing device 100 includes the fixing belt (the fixing belt of the present invention) 10, the pressure member 11, the electromagnetic induction device 12, and the pressing member 13 shown in FIG. 2. It is.

Next, transfer and heat fixing in the image forming apparatus 200 will be described below.
First, the toner images of the respective colors formed on the surface of the photosensitive drum 202 are contacted between the photosensitive drum 202 and the intermediate transfer member 212 by a bias voltage applied between the photosensitive drum 202 and the intermediate transfer member 212. 2, the toner images of the respective colors are transferred onto the outer peripheral surface of the intermediate transfer body 212 so as to coincide with the image information. The intermediate transfer member 212 having the color toner image transferred onto the outer peripheral surface in this way rotates in the direction of arrow E, and the toner image is fed to the paper feed at the pressure contact portion between the transfer roll 214 and the intermediate transfer member 212. The image is transferred to the surface of the recording medium that has been conveyed to the press contact portion by the apparatus.

  The toner image transferred to the surface of the recording medium moves in the direction of arrow A and is heated and fixed by the fixing device 100 to form an image on the surface of the recording medium. The heat fixing process is as described above, and the outer peripheral surface of the fixing belt 10 is heated by the electromagnetic induction device 12 provided to face the outer peripheral surface. This heating process is the same as the process described in the fixing device of the present invention. The fixing belt 10 whose outer peripheral surface is sufficiently heated rotates in the arrow B direction, and in the contact area with the pressure roll 11, the toner image on the surface of the recording medium inserted through the contact area in the arrow A direction is heated and melted. Heat fixing. The recording medium having the color image formed on the surface in this way is further conveyed in the direction of arrow A and discharged outside the image forming apparatus 200.

  The image forming apparatus according to the present invention does not deteriorate the heat generation characteristics of the fixing belt even when used for a long period of time, and can perform stable fixing, so that a printed matter having a high-quality image can be stably obtained. And has an effect of energy saving because standby power is small.

  Examples of the present invention will be described below. However, the method for producing the fixing belt of the present invention used in the examples is not limited to the following examples.

Example 1
A fixing belt having the layer configuration shown in FIG. 1 was produced by the following method.
As the base layer, an endless belt having a film thickness of 60 μm, an outer diameter of 30 mm, and a length of 390 mm made of polyimide resin (trade name: TX, manufactured by Unitika) was used. The outer peripheral surface of this base layer was roughened by sandblasting using # 400 alumina abrasive grains, washed, and then subjected to nickel electroless plating to form a nickel layer of 0.5 μm. Next, using this nickel electroless plating film as an electrode, a copper layer (metal heating layer) having a thickness of 10 μm was formed thereon by electrolytic plating (bright copper sulfate bath).
Subsequently, a metal protective layer having a thickness of 4.8 μm was formed on the copper layer by an electroless plating method using an electroless nickel-phosphorous plating solution (Top Nicolon LPH: manufactured by Okuno Pharmaceutical Co., Ltd.). The phosphorus content in the formed nickel-phosphorus alloy plating film was 2% by mass, and it was confirmed that this plating film was crystalline and magnetic.

When the elastic modulus of each layer was measured by the above-described tensile tester, the elastic modulus of the base layer was 400 kgf / mm ² , the elastic modulus of the metal heating layer was 2400 kgf / mm ² , and the elastic modulus of the metal protective layer was 13500 kgf / mm ^2. Met.
As a result, the value of the formula (a) of the fixing belt of Example 1 is 0.0130, which is smaller than 0.018 and satisfies the relational formula (a). Further, the value of the formula (b) is 112.8, which is 75 or more and satisfies the relational formula (b).

Subsequently, a liquid silicone rubber having a film thickness of 200 μm was applied as an elastic layer on the metal protective layer via a primer (DY39-111A / B: manufactured by Toray Dow Corning Co., Ltd.), and temporarily vulcanized. Thereafter, a primer (No. 101: Shin-Etsu Chemical Co., Ltd.) was further applied, and a PFA tube having a thickness of 30 μm was coated thereon. After that, heat treatment was performed for 120 minutes in a nitrogen purged furnace at 200 ° C. for both secondary vulcanization of silicone rubber and primer baking.
After the heat treatment, both ends of the fixing belt were cut to a length of 370 mm. A belt driving gear was fixed to one end of the belt by press-fitting.
Thus, the fixing belt of Example 1 was obtained.

<Evaluation>
-Fixing device-
The fixing belt obtained by the above-described method was attached to an electromagnetic induction heating fixing device having a pressing member, a fixing belt, a pressure roll, and an electromagnetic induction device (excitation coil) and evaluated. Details of the fixing device used in the evaluation will be described below.

  The pressing member includes a fixing belt support portion that rotatably supports the fixing belt via fixing belt driving gears at both ends of the fixing belt, and a folder having a pressure rubber pad attachment portion having a diameter smaller than the inner diameter of the fixing belt. And a pressure rubber pad provided with a sliding sheet for lowering the frictional resistance with the inner surface of the fixing belt on the side in contact with the inner surface of the fixing belt.

In assembling the fixing device, the pressing member, the fixing belt, and the pressure roll were arranged as follows.
First, after fixing the pressure rubber pad to the pad mounting portion of the folder, the pressing member is inserted into the inner peripheral side of the fixing belt, and the fixing belt driving gear on the side where the fixing belt driving gear is fixed beforehand is fixed to the fixing belt. Attached to the support. Subsequently, a fixing belt driving gear was also attached to the end portion on the release side of the fixing belt. Subsequently, the rubber pad of the pressing member and the pressure roll are placed by bringing a part of the outer circumferential surface of the fixing belt into contact with the pressure roll and applying a load between the shaft of the pressure roll and the pressure member. Pressure contact was made through a fixing belt.
As a material constituting the fixing belt fixing gear and the folder, a resin (PPS or the like) that does not generate an induced electromotive force due to an alternating current and has heat resistance in a fixing temperature region is used.

  The exciting coil used in the fixing device is a litz wire in which 16 φ0.5 mm copper wires that are insulated from each other are bundled, and this is longer than the width of the fixing belt and the circumferential length of the fixing belt. In order to make the gap between the exciting coil and the fixing belt uniform, the winding is wound so as to cover 1/6 to 1/4 of that of the fixing belt and has a curvature that follows the curvature of the fixing belt. Formed. The fixing coil was fixed on the outer peripheral surface of the fixing belt so that the gap between the exciting coil and the fixing belt was 2 mm.

  At the time of fixing, an alternating current is passed through the excitation coil by an excitation circuit to generate a magnetic field around the excitation coil. Therefore, when the generated magnetic field crosses the metal heating layer of the fixing belt, an eddy current is generated in the metal heating layer that generates a magnetic field in a direction that cancels the magnetic field crossed by electromagnetic induction. Thereby, heat generation according to the eddy current value at this time and the resistance of the metal heat generating layer is obtained.

The pressure roll is formed by providing a foamed silicone rubber layer having a film thickness of 12 mm as an elastic layer on a solid shaft having an outer diameter of 16 mm, and further covering this layer with a PFA tube having a film thickness of 30 μm.
Specifically, this pressure roll was produced as follows. First, a fluororesin tube having an outer diameter of 50 mm, a length of 340 mm, and a thickness of 30 μm, in which an adhesive primer was applied to the inner peripheral surface of the PFA tube, and a solid shaft were set in a molding die. Subsequently, after injecting liquid foamed silicone rubber to a thickness of 2 mm between the fluororesin tube and the solid shaft, the rubber layer is vulcanized and foamed by heat treatment (150 ° C. × 2 hrs) to form an elastic layer. The pressure roll was produced by forming.

As the evaluation apparatus 1, a motor was connected to the pressure roll via a gear, and the belt was driven by driving the pressure roll to convey the recording material.
As the evaluation device 2, a motor was connected to the belt driving gear, and the fixing belt was driven to drive the pressure roll to convey the recording material.

-Evaluation method-
In the above-described electromagnetic induction heating and fixing device, the evaluation method is to perform a paper passing test using J paper (A4 size vertical feed) manufactured by Fuji Xerox Co., Ltd. at a speed of 20 sheets per minute up to 400,000 sheets, and cracking of the metal heating layer. The number of sheets passed until the occurrence of the problem was evaluated. As a target, from the viewpoint of practicality, it was decided that no cracks occurred up to 200,000 sheets.
As the heat generation characteristics, the warm-up time (however, the fixable temperature to be reached was set to 180 ° C.) was evaluated. The results are shown in Table 1.
The specific measurement / evaluation method for the warm-up time is as follows.

<Warm-up time>
When the electromagnetic induction coil is energized while rotating the belt with the pressure roll separated, the surface temperature of the fixing belt is measured with a non-contact infrared radiation thermometer (manufactured by Keyence Corporation). The time until the temperature reached 180 ° C. was defined as the warm-up time.

(Example 2)
The plating solution for forming the metal protective layer used in Example 1 was replaced with an electroless nickel-phosphorous plating solution (Nickel Boomer HP-55: manufactured by Nippon Chemical Industry Co., Ltd.), and the thickness was changed to 5. A fixing belt was produced in the same manner as in Example 1 except that a 4 μm metal protective layer was formed. The phosphorus content in the formed nickel-phosphorous alloy plating film was 11% by mass, and it was confirmed that this plating film was amorphous and non-magnetic.

The elastic modulus of the formed metal protective layer was 10500 kgf / mm ² . Thus, in the fixing belt of Example 2, the value of the formula (a) is 0.0143, which is smaller than 0.018 and satisfies the relational formula (a). Further, the value of the expression (b) is 104.7, which is 75 or more and satisfies the relational expression (b).
Table 1 shows the results of the same evaluation as in Example 1 for the obtained fixing belt.
The fixing belt of Example 2 had excellent durability because the metal protective layer was amorphous. Further, since the metal protective layer is non-magnetic, the heat generation efficiency is good and the warm-up time is short.

(Example 3)
The plating solution for forming the metal protective layer used in Example 1 was replaced with a nickel-boron plating solution (Top Chemialoy B-1: manufactured by Okuno Pharmaceutical Co., Ltd.), and a thickness of 4.2 μm by an electroless plating method. A fixing belt was produced in the same manner as in Example 1 except that the metal protective layer was formed. The boron content in the formed nickel-boron alloy plating film was 0.3% by mass, and this plating film was confirmed to be crystalline and magnetic.

The elastic modulus of the formed metal protective layer was 14100 kgf / mm ² . Thus, in the fixing belt of Example 3, the value of the formula (a) is 0.0131, which is smaller than 0.018 and satisfies the relational formula (a). Further, the value of the expression (b) is 107.2, which is 75 or more, which satisfies the relational expression (b).
Table 1 shows the results of the same evaluation as in Example 1 for the obtained fixing belt.

Example 4
The plating solution for forming the metal protective layer used in Example 1 was added to a nickel-boron plating solution (Top Chemialloy B-1: manufactured by Okuno Pharmaceutical Co., Ltd., with 4 kg / L of dimethylamine borane). Instead, a fixing belt was produced in the same manner as in Example 1 except that a 4.6 μm thick metal protective layer was formed by electroless plating. The formed nickel-boron alloy plating film had a boron content of 4.0% by mass, and this plating film was confirmed to be amorphous and magnetic.

The elastic modulus of the formed metal protective layer was 13000 kgf / mm ² . Thus, in the fixing belt of Example 4, the value of the expression (a) is 0.0133, which is smaller than 0.018 and satisfies the relational expression (a). Further, the value of the expression (b) is 107.8, which is 75 or more, which satisfies the relational expression (b).
Table 1 shows the results of the same evaluation as in Example 1 for the obtained fixing belt.
The fixing belt of Example 4 had excellent durability because the metal protective layer was amorphous.

(Example 5)
The plating solution for forming the metal protective layer used in Example 1 was added to a nickel-silicon carbide composite plating solution (Top Nicojit SC: manufactured by Okuno Pharmaceutical Co., Ltd., with 4 kg / L of dimethylamine borane). Instead, a fixing belt was produced in the same manner as in Example 1 except that a 5.2 μm thick metal protective layer was formed by electroless plating. The silicon carbide content in the plated film of the formed nickel-silicon carbide composite was 8% by mass, and it was confirmed that this plated film was crystalline and magnetic.

The elastic modulus of the formed metal protective layer was 11000 kgf / mm ² . Thus, in the fixing belt of Example 5, the value of the expression (a) is 0.0141, which is smaller than 0.018 and satisfies the relational expression (a). Further, the value of the expression (b) is 105.2, which is 75 or more, which satisfies the relational expression (b).
Table 1 shows the results of the same evaluation as in Example 1 for the obtained fixing belt.

(Example 6)
The metal protective layer in Example 1 was subjected to an electrolytic nickel plating Watt bath (nickel sulfate 250 g / L, nickel chloride 45 g / L, boric acid 45 g / L, top serina 95X: 15 ml / L manufactured by Okuno Pharmaceutical Co., Ltd., A fixing belt was produced in the same manner as in Example 1 except that a pit inhibitor 1 ml / L) was used and a metal protective layer having a thickness of 9.0 μm formed by electrolytic plating was used. The metal protective layer was confirmed to be crystalline and magnetic.

The elastic modulus of the formed metal protective layer was 5500 kgf / mm ² . Thus, in the fixing belt of Example 6, the value of the expression (a) is 0.0178, which is smaller than 0.018 and satisfies the relational expression (a). Further, the value of the formula (b) is 97.5, which is 75 or more and satisfies the relational formula (b).
Table 1 shows the results of the same evaluation as in Example 1 for the obtained fixing belt.

(Example 7)
A fixing belt was produced in the same manner as in Example 6, except that the thickness of the base layer was 50 μm and the thickness of the metal protective layer was 6.0 μm.
Thus, in the fixing belt of Example 7, the value of the expression (a) is 0.0154, which is smaller than 0.018 and satisfies the relational expression (a). Further, the value of the formula (b) is 77.0, which is 75 or more and satisfies the relational formula (b).
Table 1 shows the results of the same evaluation as in Example 1 for the obtained fixing belt.

(Comparative Example 1)
A fixing belt was produced in the same manner as in Example 6 except that the thickness of the metal protective layer in Example 6 was changed to 6.0 μm.
Thus, in the fixing belt of Comparative Example 1, the value of the formula (a) is 0.0181, which is 0.018 or more and does not satisfy the relational formula (a). Further, the value of the formula (b) is 81.0, which is 75 or more and satisfies the relational formula (b).
Table 1 shows the results of the same evaluation as in Example 1 for the obtained fixing belt.
Since the fixing belt of Comparative Example 1 does not satisfy the relational expression (a), the durability against bending is insufficient, and the evaluation using the evaluation device 2 is 8 in the evaluation using the evaluation device 1 when passing 100,000 sheets in the evaluation using the evaluation device 1. When 10,000 sheets were passed, several local temperature drops were confirmed, and cracks were confirmed in the metal protective layer and the metal heat generating layer at the temperature drop points.

(Comparative Example 2)
A belt was produced in the same manner as in Example 6 except that the thickness of the metal protective layer was changed to 12.0 μm in Example 6.
Thus, in the fixing belt of Comparative Example 2, the value of the formula (a) is 0.0180, which is 0.018 or more and does not satisfy the relational formula (a). Further, the value of the expression (b) is 114.0, which is 75 or more, which satisfies the relational expression (b).
Table 1 shows the results of the same evaluation as in Example 1 for the obtained fixing belt.
Since the fixing belt of Comparative Example 2 does not satisfy the relational expression (a), durability against bending is insufficient, and when evaluation is performed using the evaluation apparatus 1, 120,000 sheets are passed, and evaluation using the evaluation apparatus 2 is 100,000. At the time of sheet passing, several local temperature drops were confirmed, and cracks were confirmed in the metal protective layer and the metal heating layer at the temperature drop points.

(Comparative Example 3)
A fixing belt was produced in the same manner as in Example 7, except that the thickness of the metal protective layer was changed to 5.0 μm in Example 7.
Thus, in the fixing belt of Comparative Example 3, the value of the expression (a) is 0.0155, which is smaller than 0.018 and satisfies the relational expression (a). However, the value of the expression (b) is 71.5, which is smaller than 75 and does not satisfy the relational expression (b).
Table 1 shows the results of the same evaluation as in Example 1 for the obtained fixing belt.
Since the fixing belt of Comparative Example 3 does not satisfy the relational expression (b), the durability against torsional stress is insufficient, and in the evaluation using the evaluation apparatus 1, the evaluation using the evaluation apparatus 2 is 6 in the evaluation using the evaluation apparatus 1. When 10,000 sheets were passed, several local temperature drops were confirmed, and cracks were confirmed in the metal protective layer and the metal heat generating layer at the temperature drop points.

(Comparative Example 4)
A fixing belt was produced in the same manner as in Example 1 except that the thickness of the metal protective layer in Example 1 was changed to 0.5 μm.
Thus, in the fixing belt of Comparative Example 4, the value of the expression (a) is 0.0202, which is 0.018 or more, and does not satisfy the relational expression (a). Further, the value of the expression (b) is 54.8, which is smaller than 75 and does not satisfy the relational expression (b). Furthermore, since the metal protective layer is too thin, the protective effect is small, and the neutral line position is separated from the metal heating layer.
Table 1 shows the results of the same evaluation as in Example 1 for the obtained fixing belt.
The fixing belt of Comparative Example 4 does not satisfy the relational expression (a) and the relational expression (b), and further, since the neutral line position is away from the metal heating layer, the durability against bending and twisting stress of the belt is insufficient. In the evaluation using the evaluation apparatus 1, a decrease in temperature was confirmed in a wide range of the fixing belt when 50,000 sheets were passed, and when evaluation using the evaluation apparatus 2 was 30,000 sheets. Moreover, generation | occurrence | production of the fine crack was confirmed in the metal-protection layer and the metal heat generating layer in the temperature fall part.

  As is apparent from Table 1, it can be seen that the fixing belts of Examples 1 to 7 are free from cracks in the metal heat generating layer even when subjected to a paper feeding test of 200,000 sheets. As a result, it can be seen that in the fixing belts of Examples 1 to 7, a decrease in durability of the metal heat generation layer is suppressed, and stable heat generation characteristics can be maintained over a long period of time.

FIG. 3 is a schematic cross-sectional view illustrating a configuration example of a fixing belt of the present invention. 1 is a schematic cross-sectional view illustrating an example of an electromagnetic induction heating fixing device (a fixing device of the present invention) using a fixing belt of the present invention. 1 is a schematic diagram illustrating a configuration example of an image forming apparatus of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Fixing belt 10a ... Base layer 10b ... Metal heating layer 10c ... Metal protective layer 10d ... Elastic layer 10e ... Release layer 11 ... Pressure member 11a ... Base material 11b ... Elastic layer 11c ... Release layer 12 ... Electromagnetic induction device ( Electromagnetic induction heating means)
12a ... Electromagnetic induction coil (excitation coil)
DESCRIPTION OF SYMBOLS 13 ... Press member 14 ... Unfixed toner image 15 ... Recording medium 100 ... Fixing apparatus 200 ... Image forming apparatus 202 ... Photosensitive drum (image holding body)
204: Charging device (charging means)
206 ... Laser scanner (latent image forming means)
208 ... Mirror 210 ... Developing device (Developing means)
212 ... Intermediate transfer member 214 ... Transfer roll (transfer means)

Claims (12)

It has a base layer, a metal heat generating layer, and a metal protective layer in this order from the inner peripheral side. The base layer has an elastic modulus Eb (kgf / mm ² ), a thickness tb (mm), and an elastic modulus of the metal heat generating layer. Eh (kgf / mm ² ), thickness th (mm), elastic modulus Ep (kgf / mm ² ), and thickness tp (mm) of the metal protective layer satisfy the following formulas (a) and (b). A fixing belt characterized by that.

  The fixing belt according to claim 1, wherein the metal protective layer contains a metal mainly composed of nickel.   The fixing belt according to claim 1, wherein the metal protective layer contains a nickel composite.   The fixing belt according to claim 1, wherein the metal protective layer contains a nickel composite and is formed by an electroless plating method.   The fixing belt according to claim 3, wherein the nickel composite is a nickel-phosphorus alloy.   The fixing belt according to claim 5, wherein a content of phosphorus in the nickel-phosphorous alloy is 1 to 12% by mass.   The fixing belt according to claim 3, wherein the nickel composite is a nickel-boron alloy.   The fixing belt according to claim 7, wherein a content of boron in the nickel-boron alloy is 0.1 to 6% by mass.   The fixing belt according to claim 3, wherein the nickel composite is a nickel-silicon carbide composite.   The fixing belt according to claim 9, wherein a content of silicon carbide in the nickel-silicon carbide composite is 1 to 15% by mass. A fixing belt having a metal heat generating layer rotatably disposed; an electromagnetic induction heating means which is disposed at a position facing the outer peripheral surface of the fixing belt and generates a magnetic field to heat the metal heat generating layer; and the fixing belt And a pressure member that heats and fixes an unfixed toner image on the recording medium, and is in contact with the inner peripheral surface of the fixing belt, and is fixed toward the pressure member. A pressing member that presses the belt,
The fixing device according to claim 1, wherein the fixing belt is the fixing belt according to claim 1. An image carrier, a charging unit for charging the surface of the image carrier, a latent image forming unit for forming a latent image on the charged surface of the image carrier, and developing the latent image with toner to form an unfixed toner image At least a developing unit that transfers the unfixed toner image onto a recording medium, and a fixing unit that heat-fixes the unfixed toner image onto the recording medium.
An image forming apparatus, wherein the fixing unit is the fixing device according to claim 11.

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