JP2021076709A - Fixing belt, fixing device, and image forming apparatus - Google Patents

Abstract

To provide an image forming apparatus that can prevent fixing failure of a mold release agent and toner to a recording material.SOLUTION: An image forming apparatus is configured which comprises an image forming unit that forms a toner image on a recording material, and a fixing unit that fixes an unfixed toner image to the recording material. The fixing unit has an endless fixing belt, a roller that pivotally supports the fixing belt, a heating unit for the fixing belt, and a pressure roller that is urged against the fixing belt. The fixing belt has a base layer and a surface layer formed on the base layer, and the value of the modulus of viscoelasticity R(%) satisfies 65.0<R<71.0.SELECTED DRAWING: Figure 5

Description

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

Conventionally, in an electrophotographic image forming apparatus including a copier and a laser beam printer, a heated fixing belt is brought into contact with a transfer material carrying an unfixed toner image to transfer the toner image. A fixing device for fixing to the material is adopted. As such a fixing device, a configuration having an endless fixing belt and two or more rollers including a fixing roller and a heating roller that pivotally support the fixing belt is known.

Further, in the image forming apparatus, the fixing portion is formed by the fixing device having the above configuration and a pressurizing roller that sandwiches the fixing belt and presses the fixing roller with a predetermined pressure. In the fixing portion of the image forming apparatus, the toner image is fixed on the recording material by sandwiching the recording material to which the unfixed toner is transferred between the fixing belt heated via the heating roller and the pressure roller.

The fixing belt has, for example, a structure in which a surface layer, an elastic layer, and a base layer are laminated in this order, and by controlling the surface roughness of the surface layer, it is possible to suppress fixing defects and improve image quality. Has been proposed (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2012-108545

However, there is a limit to the performance improvement in the releasability between the fixing belt and the recording material only by controlling the surface roughness as in the fixing belt having the configuration described in Patent Document 1 described above. In particular, in an image forming apparatus that has been increased in size and processed at high speed, high releasability is required for the fixing belt and the recording material.

In order to solve the above-mentioned problems, the present invention provides a fixing belt, a fixing device, and an image forming device capable of suppressing releasability from a recording material and poor fixing of toner.

The fixing belt of the present invention includes a base layer and a surface layer formed on the base layer, and the viscoelastic modulus R (%) satisfies 65.0 <R <71.0.

Further, the fixing device of the present invention includes an endless fixing belt, two or more rollers that pivotally support the fixing belt, a heating portion for heating the fixing belt, and one of the rollers via the fixing belt. It is provided with a pressure roller arranged so as to be relatively biased with respect to the relative. The fixing belt has a base layer and a surface layer formed on the base layer, and the value of the viscoelastic modulus R (%) of the fixing belt satisfies 65.0 <R <71.0.

Further, in the image forming apparatus of the present invention, an image forming unit that forms a toner image on a recording material by an electrophotographic method and an unfixed toner image formed on the recording material are fixed to the recording material by heating and pressurizing. It is provided with a fixing portion to be used. The fixing part is relative to one of the rollers via the fixing belt, the endless fixing belt, two or more rollers that pivotally support the fixing belt, the heating part for heating the fixing belt, and the fixing belt. It has a pressure roller arranged to be urged to. The fixing belt has a base layer and a surface layer formed on the base layer, and the viscoelastic modulus R (%) satisfies 65.0 <R <71.0.

According to the present invention, it is possible to provide a fixing belt, a fixing device, and an image forming device capable of suppressing releasability from a recording material and poor fixing of toner.

It is a figure which shows the schematic structure of the image forming apparatus. It is a figure which shows the schematic structure of the fixing device. It is a perspective view of a fixing belt. It is sectional drawing of the fixing belt. It is a figure which shows the relationship between the viscoelastic modulus of a fixing belt, the releasability and the image quality.

Hereinafter, examples of embodiments for carrying out the present invention will be described, but the present invention is not limited to the following examples.
The explanation will be given in the following order.
1. 1. Embodiment of the image forming apparatus 2. Embodiment of fixing belt

<1. Embodiment of image forming apparatus>
[Configuration of image forming apparatus]
FIG. 1 shows a schematic configuration of an image forming apparatus. The image forming apparatus 10 shown in FIG. 1 includes an image reading unit 20, an image forming unit 30, an intermediate transfer unit 40, a fixing device 60, and a recording material conveying unit 80.

The image reading unit 20 reads an image from the document D and obtains image data for forming an electrostatic latent image. The image reading unit 20 includes a paper feeding device 21, a scanner 22, a CCD sensor 23, and an image processing unit 24.

The image forming unit 30 includes, for example, four image forming units 31 corresponding to each color of yellow, magenta, cyan, and black. The image forming unit 31 includes a photoconductor drum 32, a charging device 33, an exposure device 34, a developing device 35, and a cleaning device 36.

The photoconductor drum 32 is, for example, a negatively charged organic photoconductor having photoconductivity. The charging device 33 charges the photoconductor drum 32. The charging device 33 is, for example, a corona charging device. The charging device 33 may be a contact charging device that charges a contact charging member such as a charging roller, a charging brush, or a charging blade by contacting the photoconductor drum 32. The exposure apparatus 34 irradiates the charged photoconductor drum 32 with light to form an electrostatic latent image. The exposure apparatus 34 is, for example, a semiconductor laser. The developing device 35 supplies toner to the photoconductor drum 32 on which the electrostatic latent image is formed to form a toner image corresponding to the electrostatic latent image. The developing device 35 is, for example, a known developing device in an electrophotographic image forming device. The cleaning device 36 removes residual toner from the photoconductor drum 32. Here, the "toner image" refers to a state in which toner is collected in an image shape.

As the toner, a known toner can be used. The toner may be a one-component developer or a two-component developer. The one-component developer is composed of toner particles. The two-component developer is composed of toner particles and carrier particles. The toner particles are composed of toner matrix particles and an external additive such as silica adhering to the surface thereof. The toner matrix particles are composed of, for example, a binder resin, a colorant and a wax.

The intermediate transfer unit 40 includes a primary transfer unit 41 and a secondary transfer unit 42.
The primary transfer unit 41 includes an intermediate transfer belt 43, a primary transfer roller 44, a backup roller 45, a plurality of first support rollers 46, and a cleaning device 47. The intermediate transfer belt 43 is an endless belt. The intermediate transfer belt 43 is stretched by the backup roller 45 and the first support roller 46. The intermediate transfer belt 43 travels on an endless track at a constant speed in one direction by rotationally driving at least one of the backup roller 45 and the first support roller 46.

The secondary transfer unit 42 includes a secondary transfer belt 48, a secondary transfer roller 49, and a plurality of second support rollers 50. The secondary transfer belt 48 is an endless belt. The secondary transfer belt 48 is stretched by the secondary transfer roller 49 and the second support roller 50.

The recording material transport unit 80 has three paper feed tray units 81 and a plurality of resist roller pairs 82. The paper feed tray unit 81 accommodates recording materials S (standard paper, special paper, etc.) identified based on the basis weight, size, and the like for each preset type. The resist roller pair 82 is arranged so as to form a desired transport path.

In such an image forming apparatus 10, a toner image is transferred to the recording material S sent by the recording material transport unit 80 by the intermediate transfer unit 40 based on the image data acquired by the image reading unit 20. It is formed. The recording material S on which the toner image is formed by the intermediate transfer unit 40 is sent to the fixing device 60.

The fixing belt 61 in the fixing device 60 is rotationally driven at a predetermined speed in accordance with the arrival of the recording material S. Further, in the fixing device 60, the second pressure roller 64 urges the outer peripheral surface of the first pressure roller 63 via the fixing belt 61, so that the fixing belt 61 and the second pressure roller 64 are urged. A fixing nip portion is formed between the pressure roller 64 and the pressure roller 64.

The recording material S that supports the unfixed toner image is brought into close contact with the fixing belt 61 at the fixing nip portion, so that the unfixed toner image is quickly fixed to the recording material S. Further, the recording material S receives the airflow from the airflow separating device 69 at the downstream end of the fixing nip portion. Therefore, the separation of the recording material S from the fixing belt 61 is promoted. The recording material S separated from the fixing belt 61 is guided to the outside of the image forming apparatus 10.

[Structure of fixing device]
FIG. 2 shows the configuration of the fixing device 60 mounted on the image forming device 10.
As shown in FIG. 2, the fixing device 60 includes a fixing belt 61, a heating roller 62, a first pressurizing roller 63, a second pressurizing roller 64, heaters 65 and 66, and a first temperature sensor 67. , A second temperature sensor 68, an air flow separation device 69, a guide plate 70, and a guide roller 71.

The fixing belt 61 is pivotally supported by the heating roller 62 and the first pressure roller 63. The tension of the fixing belt 61 is, for example, 43N. Since one of the features of this embodiment is the fixing belt 61, a detailed description of the fixing belt 61 will be described later.

The heating roller 62 has a rotatable aluminum sleeve and a heater 65 (heating portion) arranged inside the sleeve. The first pressure roller 63 has, for example, a rotatable core metal and an elastic layer arranged on the outer peripheral surface thereof.

The second pressure roller 64 is arranged so as to face the first pressure roller 63 via the fixing belt 61. The second pressurizing roller 64 has, for example, a rotatable aluminum sleeve and a heater 66 (heating portion) arranged in the sleeve. The second pressurizing roller 64 is arranged so as to be able to approach and separate from the first pressurizing roller 63, and when approaching the first pressurizing roller 63, the first pressurizing roller 64 is applied via the fixing belt 61. The elastic layer of the pressure roller 63 is pressed to form a fixing nip portion which is a contact portion with the fixing belt 61.

In the fixing device 60, the roller diameter can be appropriately set according to the excellent separability and fixing property of the fixing belt and a desired image forming speed. For example, the roller diameters of the first pressure roller 63 and the second pressure roller 64 urged via the fixing belt 61 are preferably large from the viewpoint of being able to support high-speed image formation, for example, 50 mm or more. It is preferably 60 mm or more, and more preferably 60 mm or more. By setting the roller diameter in the above range, the fixability of the toner image to the recording material S at the time of fixing is likely to be improved.

The fixing belt 61 is supported in a state of being stretched by a plurality of rollers, that is, in a state of applying a predetermined tension. If the tension is too large, the physical properties that contribute to the adhesion of the fixing belt to the recording material S, such as the elasticity of the elastic layer, may be insufficiently expressed in the fixing nip portion. From the viewpoint of the adhesion, the tension is preferably 45 N or less, and more preferably 50 N or less. The tension may be large enough to maintain the shape of the endless track formed by the fixing belt being supported by the rollers, and may be, for example, 20 N or more.

The first temperature sensor 67 is a device for detecting the temperature of the fixing belt 61 heated by the heating roller 62. The second temperature sensor 68 is a device for detecting the temperature of the outer peripheral surface of the second pressurizing roller 64.

The fixing belt 61 is heated to a desired temperature (for example, 190 ° C.) by the heater 65 by feedback control by the first temperature sensor 67, for example. The second pressurizing roller 64 is heated to a desired temperature (for example, 180 ° C.) by the heater 66, for example, by feedback control by the second temperature sensor 68.

The air flow separation device 69 is a device for generating an air flow from the downstream side in the moving direction of the fixing belt 61 toward the fixing nip portion to promote the separation of the recording material S from the fixing belt 61.

The guide plate 70 is a member for guiding the recording material S having an unfixed toner image to the fixing nip portion. The guide roller 71 guides the recording material on which the toner image is fixed from the fixing nip portion to the outside of the image forming apparatus 10.

<2. Embodiment of fixing belt>
Next, the fixing belt 61 will be described in detail. FIG. 3 is a perspective view of the fixing belt 61, and FIG. 4 is an enlarged view of the region A shown in FIG.

As shown in FIGS. 3 and 4, the fixing belt 61 has a base layer 61a, an elastic layer 61b, and a surface layer 61c. Further, in the fixing belt 61, the base layer 61a is located on the inner peripheral surface side of the fixing device 60, and the surface layer 61c is located on the outer peripheral surface side.

[Base layer]
The base layer 61a is made of a material containing a heat-resistant resin. “Heat resistance” means that the toner image is sufficiently stable at the temperature (for example, 150 to 220 ° C.) when the fixing belt is used for fixing the toner image to the recording material S in electrophotographic image formation, and the desired physical properties. Means to express.

The heat-resistant resin is appropriately selected from resins that do not undergo modification or deformation within the operating temperature range of the fixing belt 61, and may be one kind or more. Examples of heat resistant resins include polyphenylene sulfide, polyarylate, polysulfone, polyethersulfone, polyetherimide, polyimide, polyamideimide and polyetheretherketone. As the heat-resistant resin, polyimide is preferable from the viewpoint of heat resistance.

Polyimide can be obtained by heating the precursor polyamic acid at a temperature of 200 ° C. or higher, or by advancing the dehydration / cyclization (imidization) reaction of the polyamic acid using a catalyst. The polyamic acid may be produced by dissolving tetracarboxylic dianhydride and a diamine compound in a solvent and performing a polycondensation reaction by mixing and heating, or a commercially available product may be used. Examples of the diamine compound and the tetracarboxylic dianhydride include the compounds described in paragraphs [0123] to [0130] of JP2013-25120A.

The content of the heat-resistant resin in the base layer 61a may be an amount sufficient to form the base layer 61a, for example, preferably 50% by mass or more, and more preferably 60 to 75% by mass. , 76-90% by mass, more preferably.

The base layer 61a may further contain components other than the heat-resistant resin. For example, the base layer 61a may further contain a filler. The filler contributes to, for example, improving at least one of the hardness, heat transferability and conductivity of the base layer 61a. The filler contained in the base layer 61a may be one kind or more, and examples of the material include carbon black, Ketjen black, nanocarbon and graphite.

If the content of the filler in the base layer 61a is too large, the toughness of the base layer 61a may be lowered, and the fixability and separability of the fixing belt 61 may be lowered. On the other hand, if the amount is too small, the desired effect of the filler, such as imparting appropriate conductivity, may be insufficient. From such a viewpoint, the content of the filler in the base layer 61a is preferably 3% by mass or more, more preferably 4% by mass or more, and further preferably 5% by mass or more. The content of the filler in the base layer 61a is preferably 30% by mass or less, more preferably 20% by mass or less, and further preferably 10% by mass or less.

[Elastic layer]
The elastic layer 61b is a layer having elasticity that contributes to the improvement of the contact property between the surface of the fixing belt 61 at the fixing nip portion and the recording material S that carries the unfixed toner image. The elastic layer 61b is configured to include an elastic material. “Elasticity” refers to a deformation in which the fixing belt 61 sufficiently contacts the surface of the recording material S having an unfixed toner image in fixing the toner image to the recording material S in electrophotographic image formation. Means to give to.

The elastic material constituting the elastic layer 61b may be one kind or more, and is, for example, a material having a loss tangent tan δ (ratio of loss elastic modulus to storage elastic modulus) at 20 Hz of 0.2 or less. Examples of elastic materials include elastic resin materials, such as silicone rubbers, thermoplastic elastomers and rubber materials. Above all, the elastic material is preferably silicone rubber from the viewpoint of heat resistance as well as elasticity.

The silicone rubber constituting the elastic layer 61b may be one kind or more. Examples of the silicone rubber include polyorganosiloxane and a heat-cured product thereof, and an addition reaction type silicone rubber described in JP-A-2009-122317. Examples of the polyorganosiloxane include dimethylpolysiloxane having both ends sealed with a trimethylsiloxane group and having a vinyl group in the side chain described in paragraph [0029] of JP-A-2008-255283.

The thickness of the elastic layer 61b is preferably 30 to 400 μm, more preferably 50 to 300 μm, and even more preferably 100 to 250 μm, for example, from the viewpoint of sufficiently exhibiting heat transferability and elasticity. ..

The elastic layer 61b may further contain components other than the elastic resin material. For example, the elastic material may further contain a heat-conducting filler to enhance the heat-conducting property of the elastic layer. Examples of filler materials include silica, metallic silica, alumina, zinc, aluminum nitride, boron nitride, silicon nitride, silicon carbide, carbon and graphite. The form of the filler is not limited, for example, spherical powder, amorphous powder, flat powder or fiber.

The content of the elastic resin material in the elastic material is preferably 60 to 100% by volume, more preferably 75 to 100% by volume, and even more preferably 80 to 100% by volume.

[surface]
The surface layer 61c is a layer having a releasability that contributes to the improvement of the releasability of the fixing belt 61 from the surface of the fixing nip portion to the molten toner layer on the recording material S. That is, the surface layer 61c has an appropriate releasability with respect to the toner component. The surface layer 61c constitutes the outer surface of the fixing belt 61 that comes into contact with the recording material S at the time of fixing.

Examples of the material constituting the surface layer 61c include polyethylene, polypropylene, polystyrene, polyisobutylene, polyester, polyurethane, polyamide, polyimide, polyamideimide, alcohol-soluble nylon, polycarbonate, polyallylate, phenol, polyoxymethylene, and polyetheretherketone. , Polyphosphazene, polysulfone, polyethersulfide, polyphenylene oxide, polyphenylene ether, polyparavanic acid, polyallylphenol, fluororesin, polyurea, ionomer, silicone, and mixtures or copolymers thereof. As the material constituting the surface layer 61c, it is preferable that the material of the surface layer 61c contains a fluororesin from the viewpoint of releasability and heat resistance. Fluororesin includes, for example, perfluoroalkoxy alkane resin (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP) and tetrafluoroethylene-ethylene copolymer (ETFE). In particular, the surface layer 61c more preferably contains a perfluoroalkoxy alkane resin (PFA).

The thickness of the surface layer 61c is preferably 5 to 40 μm, more preferably 10 to 35 μm, and more preferably 10 to 35 μm, for example, from the viewpoint of heat transfer, follow-up to deformation of the elastic layer, and development of releasability. It is more preferably ~ 30 μm.

The surface layer 61c may further contain components other than the above resin material. For example, the surface layer 61c may further contain lubricant particles. Examples of lubricant particles include fluororesin particles, silicone resin particles and silica particles. The content of the resin material in the material of the surface layer 61c is preferably 70 to 100% by volume from the viewpoint of heat transferability and flexibility that sufficiently follows the deformation of the elastic layer.

[Other layers]
The fixing belt 61 may further have layers other than the base layer 61a, the elastic layer 61b, and the surface layer 61c described above. Examples of other layers include a reinforcing layer.

The reinforcing layer is a layer for increasing the mechanical strength of the fixing belt 61, and is arranged, for example, on the surface of the fixing belt 61 opposite to the elastic layer 61b and the surface layer 61c (inner peripheral surface of the base layer 61a). The reinforcing layer can be made of the above-mentioned heat-resistant resin, and its thickness can be appropriately determined.

The fixing belt 61 can be manufactured by using a known method for manufacturing a laminated fixing belt. For example, the fixing belt 61 has a step of covering the outer surface of an endless molded body made of heat-resistant resin serving as a base layer 61a with a tube serving as a surface layer 61c, and an elastic material or a precursor thereof between the molded body and the tube. It can be produced by a method including a step of injecting and, if necessary, a step of heat-curing the elastic material or precursor.

[Viscoelastic modulus]
The fixing belt 61 has a viscoelastic modulus R of 65.0 <R <71.0. More preferably, the viscoelastic modulus R satisfies 68.0 <R <70.0. By satisfying the above conditions, the releasability of the fixing belt 61 from the recording material S can be improved, and poor fixing of the toner image can be suppressed.

When the viscoelasticity of the fixing belt 61 is within the above range, the apparent viscosity of the fixing belt 61 increases, so that the resilience of the fixing belt 61 decreases. As a result, the resilience of the fixing belt 61 is reduced, so that the toner image is less likely to separate from the fixing belt 61 in the nip, and the toner image follows the fixing belt 61 and easily moves in the nip. Therefore, it is possible to suppress poor fixing of the toner image to the recording material SS.
Further, when the viscoelasticity is within the above range, sufficient elasticity (repulsive force) is obtained for the fixing belt 61 at the nip outlet, and the recording material S can be easily released from the fixing belt 61.

The viscoelastic modulus of the fixing belt 61 is obtained by causing the fixing belt 61 to undergo a constant change, tracking its deformation behavior, and quantifying it using a Voigt model. The unit of viscoelasticity is%. The viscoelastic modulus can be expressed by [viscous strain amount / (elastic strain amount + viscous strain amount)]. The viscoelasticity can be measured using, for example, a viscoelasticity measuring machine (Vesmeter E-200DT, manufactured by Web Cyber). The vesmeter applies a constant external force to the object to be measured, slightly deforms the object to be measured, removes the external force, and tracks the state of the object to be measured after the external force is removed. To track. Then, the viscoelasticity is measured by performing waveform analysis at the time of restoration. The viscoelasticity of the fixing belt 61 is measured by fixing the inner surface (base layer 61a) side of the fixing belt 61 to the viscoelasticity measuring machine and contacting the measuring indenter of the device from the outside (surface layer 61c side).

Further, the viscoelasticity of the fixing belt 61 can be adjusted by surface treatment of the surface layer 61c. As the surface treatment of the surface layer 61c, it is preferable to perform a blast treatment because a desired viscoelastic modulus can be easily obtained.

The blasting treatment for the fixing belt 61 is performed by, for example, the following method.
The fixing belt 61 is fixed in a direct pressure type manual blasting device (FD-5-501 type, manufactured by Fuji Seisakusho Co., Ltd.) with the surface layer 61c facing outward. Then, molten alumina (center particle size: 70 μm) is blown toward the surface layer 61c as a projection material (media) to form an uneven shape on the surface of the surface layer 61c.

As the media type used for the blast treatment, for example, zirconia, stainless steel, steel, glass, walnut, zinc and the like can be used in addition to molten alumina. As the media type, alumina or zirconia that is hard to break is preferable, and alumina having an appropriate specific gravity is more preferable.
If the particle size of the media is too large, through holes are likely to occur in the surface layer 61c, and if it is too small, the energy given to the surface layer 61c is small, so that the required viscoelastic modulus cannot be obtained. Therefore, it is preferable to select the grain shape of the media according to the material and physical properties of the surface layer 61c.

In the blasting treatment, suitable conditions differ depending on the configuration of the fixing belt 61, particularly the composition of the surface layer 61c. Therefore, the media type, air pressure, spraying distance, and spraying distance are adjusted so as to obtain a desired viscoelastic modulus. It is preferable to select the spray angle. For example, when the surface layer 61c made of PFA is blasted using the above-mentioned molten alumina (center particle size: 70 μm), the air pressure is 0.1 to 0.3 MPa, the spray distance is 50 to 300 mm, and the spray angle is 90 ± 30 °. Is preferable.

The viscoelasticity can be adjusted by the above-mentioned blasting treatment, but known methods such as a method of generating and growing fluororesin crystals in the surface layer 61c and a method of mechanically polishing the surface of the surface layer 61c are known. It can also be done by a method.
For example, the viscoelastic modulus tends to decrease by increasing the molecular weight of the material (elastic component or the like) constituting the fixing belt 61 (mainly the surface layer 61c) or the like. In addition, there is a tendency to reduce the change in viscoelasticity by increasing the glass transition temperature within a predetermined temperature range. Specifically, the viscoelastic modulus is adjusted by increasing the crosslink density of the material constituting the fixing belt 61 or increasing the molecular weight to increase the hardness, or by blending the polymer type and the filler type. can do. Further, it can be adjusted by increasing the glass transition temperature.

Further, the rate of change of the viscous strain amount with respect to the elastic strain amount of the fixing belt 61 in the range of 100 to 200 ° C. is preferably 0.1 or less. Here, the "elastic strain amount" is an elastic modulus, and means a property that a strain proportional to the force is generated when a force is applied due to the property of the spring, but returns immediately when the force is released. The unit of elastic strain is N / m ² . Further, the "viscous strain amount" is a viscous coefficient, and means a property of reacting with a delay when a force is applied or released. The unit of the amount of viscous strain is N · s / m ² . When the rate of change of the amount of viscous strain with respect to the amount of elastic strain of the fixing belt 61 in the range of 100 to 200 ° C. is more than 0.1, the gloss and separability of the image due to changes in the pressing force and repulsive force of the rubber. May be affected.

The present invention will be specifically described with reference to Examples, but the present invention is not limited thereto. Unless otherwise specified, each operation was performed at room temperature (20 ° C.).

[Sample 1: Preparation method of fixing belt]
(Method of manufacturing base belt)
A varnish containing polyamic acid and 8% by mass of carbon black with respect to polyamic acid was rotationally applied to the outside of the cylindrical mold. Then, the coating film was dried at 300 to 450 ° C. and imidized to produce a cylindrical polyimide tubular material (base material belt) having an inner diameter of 99 mm, a length of 360 mm, and a thickness of 70 μm. The polyamic acid is a polymer obtained by dehydration condensation of 3,3', 4,4'-biphenyltetracarboxylic dianhydride and p-phenylenediamine.

(Preparation of surface layer and elastic layer)
Next, a stainless steel cylindrical core metal having an outer diameter of 99 mm is brought into close contact with the inside of the base material belt, and a PFA tube (surface layer) having a thickness of 30 μm is placed on the inner peripheral surface of the base material belt. It was covered with a cylindrical mold to be held in. In this way, the core metal and the cylindrical mold were held coaxially, and a cavity (gap) was formed between the two. Next, a silicone rubber material was injected into the cavity and heat-cured.
Through the above steps, a laminated belt (fixing belt before surface treatment) having an elastic layer made of silicone rubber having a thickness of 200 μm and a surface layer (PFA layer) was produced on the base belt (base layer).

The rubber hardness (type A) of the silicone rubber constituting the elastic layer is 30 °, the tensile strength is 1.5 MPa, the thermal conductivity is 0.7 W / (m · K), and the elongation is It is 250%.
The rubber hardness of the silicone rubber was measured using a rubber sheet for measurement having a thickness of 10.0 mm and using a durometer A according to JIS K6301. The rubber sheet was produced under the same conditions as those for producing the elastic layer.
The tensile strength of the silicone rubber was measured using a rubber sheet for measurement using a Tencilon universal tensile tester (manufactured by A & D Co., Ltd.).
The thermal conductivity of the silicone rubber was measured using a QTM rapid thermal conductivity meter (manufactured by Kyoto Denshi Kogyo Co., Ltd.) using the rubber sheet for measurement.
The elongation of the silicone rubber was measured using a rubber sheet for measurement using a Tencilon universal tensile tester (manufactured by A & D Co., Ltd.).

(Blasting)
The obtained laminated belt was fixed in a direct pressure type manual blasting device (FD-5-501 type, manufactured by Fuji Seisakusho Co., Ltd.) with the surface layer (PFA layer) on the outside. Then, using molten alumina (center particle size: 70 μm) as the projection material (media), the material is blown toward the surface layer under the conditions shown in Table 1 below (air pressure, spray distance, and spray angle), and is applied to the surface of the surface layer. An uneven shape was formed.
By the surface treatment using the above blasting treatment, a fixing belt of Sample 1 having an adjusted viscoelasticity was produced.

[Method for producing fixing belts for samples 2 to 6]
By changing the blasting conditions (air pressure, spraying distance, and spraying angle) to the conditions shown in Table 1 below in the above-mentioned method for producing the fixing belt of sample 1, samples 2 to 6 having different viscoelastic modulus are obtained. The fixing belt of was produced.

[Method for producing fixing belt for sample 7]
A fixing belt for Sample 7 was prepared in the same manner as in Comparative Example 3 described in paragraphs [0059] and [0065] of JP-A-2017-3765.

[Evaluation method]
The viscoelasticity, releasability, and image quality of the fixing belts of Samples 1 to 7 prepared by the above method were evaluated by the following methods.

(Viscoelastic modulus)
The prepared fixing belt was fixed to an aluminum cylindrical substrate, and the temperature was raised to room temperature, and the viscoelasticity was measured by a viscoelasticity measuring machine (Vesmeter (E-200DT); Web Cyber Co., Ltd.).

(Releasability)
In a full-color copying machine (bizhubPRESSS 1070; Konica Minolta Co., Ltd.), the genuine fixing belt was replaced with the fixing belt of Samples 1 to 7 to prepare an image forming apparatus for evaluation. Then, using this image forming apparatus for evaluation, a toner image of a magenta band-shaped solid image having a width of 5 cm in the direction perpendicular to the transport direction on A4 size plain paper (toner adhesion amount: 8 g / m ² ). The image formation for transferring the image was performed at a rate of 60 sheets / minute. The releasability between the fixing belt and the recording medium at this time was determined according to the following criteria.
A: Plain paper separates without curling.
B: Plain paper curls a little, but there is no problem.
C: Plain paper cannot be separated.

(image quality)
The strip-shaped solid image formed by the evaluation of the higher releasability was visually observed, and the image quality of the strip-shaped solid image was judged according to the following criteria. The image defect due to poor fixing is an image defect due to cold offset (roughness of appearance) or an image defect due to hot offset (occurrence of paper jam).
A: No defects due to poor fixing are found in the solid image.
B: Defects due to poor fixing are seen in the solid image.

Table 1 shows the surface modification conditions for the fixing belts of Samples 1 to 7, and the evaluation results of the viscoelasticity, releasability, and image quality of each sample.

As shown in Table 1, the elastic modulus of the fixing belt of sample 1 is 71.2, the elastic modulus of the fixing belt of sample 2 is 70.9, the elastic modulus of the fixing belt of sample 3 is 69.8, and the sample. The elastic modulus of the fixing belt of sample 4 is 69.7, the elastic modulus of the fixing belt of sample 5 is 66.3, the elastic modulus of the fixing belt of sample 6 is 63.5, and the elastic modulus of the fixing belt of sample 7 Was 64.1.

The image quality of the fixing belt of sample 1 having a viscoelastic modulus exceeding 71.0 is worse than that of other samples. Further, the fixing belts of Sample 6 and Sample 7 having a viscoelastic modulus of less than 65.0 have worse releasability than other samples.

Further, the fixing belts of Sample 3 and Sample 4 having a viscoelasticity of 68.0 or more and 70.0 or less are the fixing belt of Sample 2 having a viscoelasticity of more than 70.0 and the viscoelasticity of less than 68.0. Compared with the fixing belt of sample 5, the image quality is the same, but the releasability is further improved.

FIG. 5 shows the relationship between the viscoelastic modulus in the evaluation of the fixing belt of each sample described above, the releasability and the image quality. In FIG. 5, the horizontal axis represents the viscoelastic modulus of each sample. The left vertical axis shows the evaluation result of releasability, and the right vertical axis shows the evaluation result of image quality. In FIG. 5, the numbers of each sample are circled.

As shown in FIG. 5, the viscoelasticity of each sample and the evaluation results of releasability and image quality can be arranged linearly. That is, as shown in FIG. 5, the higher the viscoelasticity, the easier it is to improve the releasability, and the lower the viscoelasticity, the easier it is to improve the image quality. Therefore, by controlling the viscoelasticity of the fixing belt, it is possible to manufacture the fixing belt within a range in which both releasability and image quality can be achieved.

The present invention is not limited to the configuration described in the above-described embodiment, and various modifications and changes can be made without departing from the configuration of the present invention.

10 image forming device, 20 image reading unit, 21 feeding device, 22 scanner, 23 CCD sensor, 24 image processing unit, 30 image forming unit, 31 image forming unit, 32 photoconductor drum, 33 charging device, 34 exposure device, 35 developing equipment, 36, 47 cleaning equipment, 40 intermediate transfer unit, 41 primary transfer unit, 42 secondary transfer unit, 43 intermediate transfer belt, 44 primary transfer roller, 45 backup roller, 46 first support roller, 48 secondary transfer Belt, 49 Secondary transfer roller, 50 Second support roller, 60 Fixing device, 61 Fixing belt, 61a base layer, 61b elastic layer, 61c surface layer, 62 heating roller, 63 first pressure roller, 64 second pressure roller, 65, 66 Heater, 67 1st temperature sensor, 68 2nd temperature sensor, 69 Air flow separator, 70 Guide plate, 71 Guide roller, 80 Recording material carrier, 81 Feed tray unit, 82 Resist roller pair

Claims (7)

A fixing belt including a base layer and a surface layer formed on the base layer.
A fixing belt in which the viscoelastic modulus R (%) of the fixing belt satisfies 65.0 <R <71.0. The fixing belt according to claim 1, wherein the value of the viscoelastic modulus R (%) of the fixing belt satisfies 68.0 <R <70.0. The fixing belt according to claim 1 or 2, which has an elastic layer between the base layer and the surface layer. The fixing belt according to claim 3, wherein the base layer contains polyimide, the elastic layer contains silicone rubber, and the surface layer contains perfluoroalkoxy alkane resin. The fixing belt according to any one of claims 1 to 4, wherein the surface layer is modified in physical properties by blasting. With an endless fixing belt,
Two or more rollers that pivotally support the fixing belt, and
A heating unit for heating the fixing belt and
A pressure roller arranged so as to be biased relative to one of the rollers via the fixing belt.
A fixing device in which the fixing belt has a base layer and a surface layer formed on the base layer, and the value of the viscoelastic modulus R (%) of the fixing belt satisfies 65.0 <R <71.0. An image forming part that forms a toner image on a recording material by an electrophotographic method,
A fixing portion for fixing the unfixed toner image formed on the recording material to the recording material by heating and pressurizing is provided.
The fixing part
With an endless fixing belt,
Two or more rollers that pivotally support the fixing belt, and
A heating unit for heating the fixing belt and
It has a pressure roller arranged so as to be biased relative to one of the rollers via the fixing belt.
The fixing belt has a base layer and a surface layer formed on the base layer.
An image forming apparatus in which the value of the viscoelastic modulus R (%) of the fixing belt satisfies 65.0 <R <71.0.

Images