JP2007178750A - Belt for image forming apparatus and image forming apparatus provided with same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a belt for an image forming apparatus which is capable of preventing image defects due to the irregularities of the surface of the belt for the image forming apparatus caused by dust and graininess adhering to a roller and the belt. <P>SOLUTION: In the belt for the image forming apparatus, a layer comprising a curable resin composition having a hardness higher than that of a thermoplastic resin composition is formed on the inner circumferential surface of an endless belt comprising the thermoplastic resin composition, with the thickness of ≤5.0μm and the arithmetic mean roughness Ra of the inner circumferential surface of the layer comprising the curable resin composition is ≤0.10μm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a belt for an image forming apparatus, and more specifically, after toner used in an image forming apparatus such as a copying machine, a laser beam printer, or a facsimile is transferred from a photoconductor to the belt surface, it is collectively applied to paper or OHP film. An intermediate transfer belt used in an intermediate transfer system for transferring, or a belt used as a transfer / conveying belt used for transferring a medium such as paper or an OHP film and transferring toner from a photosensitive member to paper or an OHP film, and the like The present invention relates to an image forming apparatus.

  Examples of the image forming apparatus belt used in the image forming apparatus include a transfer conveyance belt and an intermediate transfer belt. An example of a type image forming apparatus using such an image forming apparatus belt as an intermediate transfer belt is shown. In the electrostatic latent image unit 100, the photosensitive drum 101 is driven to rotate at a constant speed Vf in the direction of the arrow. The surface is first uniformly charged by the charging charger 102, and an electrostatic latent image is formed by the optical writing device 103 using laser light. A developing device 104 is disposed beside the photosensitive drum. A toner 105 is accommodated in the developing device 104, and the charged toner 105 adheres to the electrostatic latent image portion and is visualized as a toner image.

  The intermediate transfer belt 106 is stretched by four rollers 107, 108, 109, and 110, and is disposed in the horizontal direction. It is driven to rotate at a constant speed Vf in the direction of the intermediate belt 106.

  In the case of a full-color image forming apparatus, the electrostatic latent image unit includes four colors 101A, 100B, 100C, and 100D for yellow, magenta, cyan, and black arranged on the intermediate transfer belt 106 and facing each other with the intermediate transfer belt interposed therebetween. Four primary transfer rollers 111A, 111B, 111C, and 111D are arranged at the positions. The toner image that is made visible on each drum is transferred to the intermediate transfer belt 106 by applying a transfer bias from the opposing primary transfer rollers 111A, 111B, 111C, and 111D (primary transfer).

  In this image forming apparatus, toner is transferred in the order of 100A, 100B, 100C, and 100D while synchronizing with the rotation of the intermediate transfer belt 106.

  Next, the secondary transfer roller 112 comes into contact with the non-image portion immediately before the leading edge of the image on the intermediate transfer belt 106, and a polarity opposite to that of the toner is applied to the secondary transfer roller 112. When the leading edge of the image on the intermediate transfer belt 106 reaches the transfer portion, the leading edge of the transfer paper 113 is sent to the nip between the intermediate transfer belt 106 and the secondary transfer roller 112 almost at the same time, and the four color toners on the intermediate transfer belt 106 are transferred. The image is collectively transferred onto the transfer paper 113 (secondary transfer). The transfer paper 112 onto which the toner image has been transferred is fixed by a fixing unit (not shown) to form an image.

  On the other hand, the remaining toner remaining on the intermediate transfer belt 106 is scraped off by a cleaning blade 114 that comes into movable contact with the stretching roller 108 at an arbitrary timing, and is collected in a waste toner box 115. Restores the initial state.

  As described above, when the image forming apparatus belt is used as the intermediate transfer belt 106, the intermediate transfer belt 106 includes the four rollers 107, 108, 109, 110, the electrostatic latent image units 100A, 100B, 100C, 100D, the primary transfer rollers 111A, 111B, 111C, 111D, the secondary transfer roller 112, the transfer paper 113, and the cleaning blade 114 are in contact with the cleaning blade 114, and a large load is applied to the belt. Breaking sometimes occurred from the end.

  Therefore, such a belt for an image forming apparatus includes a resin belt made of a thermoplastic resin having high tear strength, such as a fluororesin composition (Patent Document 1) and a polyalkylene terephthalate / polycarbonate resin composition (Patent Document 2). Has been proposed.

  In the image forming apparatus belt made of the thermoplastic resin of the conventional example, the image forming apparatus belt may have minute irregularities from the beginning or on the surface of the roller on which the image forming apparatus belt is stretched and supported. If foreign matter such as metal powder or toner aggregate adheres to the back surface, scratches will form in the circumferential direction of the roller surface due to long-term use, and the belt surface will have minute irregularities, metal powder, toner aggregates, and circumferential scratches. It is known that the corresponding unevenness is obtained. The surface unevenness of the belt for the image forming apparatus becomes a poor adhesion at the time of transfer, so that it becomes a problem that it becomes apparent as vertical stripes on the image.

As a measure against scratches on the back of image forming device belts,
1) Method of reducing the surface roughness of the roller surface on which the belt is stretched 2) Method of disposing a cleaning member for removing deposits on one of the rollers to be stretched (Patent Document 3) 3) Friction of the roller surface Methods have been proposed in which the coefficient is 0.25 or less or the friction coefficient of the roller surface is smaller than the friction coefficient of the belt back surface (Patent Document 4), and 4) the method of reducing the roughness of the belt back surface (Patent Document 5).
JP 2001-098125 A Japanese Patent No. 2845059 JP 05-333709 A JP 2004-117462 A Japanese Patent No. 3578860

  However, in the method 1), the roller surface does not have irregularities in the initial state of the roller, but scratches are generated on the roller surface due to the influence of foreign matters attached to the belt, and the belt back surface and belt surface irregularities are generated. Furthermore, in the methods 2) and 3), it is difficult to prevent scratches on the roller surface due to foreign matters adhering to the belt back surface, and finally the belt back surface and belt surface unevenness are generated. Further, in the method 4), the unevenness on the back surface of the belt is reduced, and the occurrence frequency of unevenness on the belt surface due to the belt is reduced. However, the surface scratches on the roller formed from the beginning, the back surface of the belt due to foreign matter adhering to the roller, and The belt surface unevenness occurs and image defects cannot be prevented. An object of the present invention is to solve the above problems and obtain a high-quality image.

  In order to solve the above problems, the present invention provides an inner peripheral surface of an endless belt made of a thermoplastic resin composition having a layer made of a cured resin composition having a hardness higher than that of the thermoplastic resin composition of 0.5 μm or more, Provided is a belt for an image forming apparatus, which is formed with a thickness of 5.0 μm or less and has an arithmetic average roughness Ra of an inner peripheral surface of a layer made of the cured resin composition of 0.1 μm or less.

It is more effective when the surface hardness of the layer made of the cured resin composition is 0.35 GPa or more.
It is more effective that the layer made of the cured resin composition is a cured product of an ultraviolet curable acrylic resin.

The belt for an image forming apparatus of the present invention configured as described above is sufficiently durable and can provide a high quality image.

(Basic configuration)
The belt for an image forming apparatus according to the present invention will be described below in more detail with reference to the drawings.
FIG. 2 is a schematic sectional view of a belt for an image forming apparatus according to the present invention. 201 is an endless belt made of a thermoplastic resin composition, and 202 is a layer made of a cured resin composition disposed on the inner peripheral surface of the endless belt.

The image forming apparatus belt satisfies the following items 1) to 3).
1) The hardness of the cured resin composition that is a layer disposed on the inner peripheral surface of the endless belt is higher than the hardness of the thermoplastic resin composition that is an endless belt.
2) The thickness of the cured resin composition is 0.5 μm or more and 5.0 μm or less.
3) The arithmetic average roughness Ra of the inner peripheral surface of the layer made of the cured resin composition is 0.10 μm or less.

  As described above, with the configuration of the belt for an image forming apparatus before the present invention, a stable and high-quality image could not be obtained in the initial and long-term use.

As a result of intensive studies by the present inventors, it was found that the endless belt made of a thermoplastic resin composition excellent in tear strength and the like was in contact with the directly stretched roller, resulting in unevenness of the surface of the belt for the image forming apparatus. I found that it was generated. Therefore, the present inventors arranged a layer made of a hardened cured resin composition that does not hinder the properties of the existing endless belt on the inner peripheral surface of the endless belt made of the thermoplastic resin composition, and directly made the thermoplastic resin composition. It is possible to prevent the contact between the endless belt made of a product and the roller, and to suppress the occurrence of surface irregularities of the belt for the image forming apparatus over a long period of time, and all of the above 1) to 3) are satisfied. The present inventors have found that a belt for an image forming apparatus is obtained, and have made the present invention.
Each component will be described in turn below.

(Endless belt)
The thermoplastic resin composition of the present invention comprises at least one or more thermoplastic resins and additives, and the thermoplastic resin is preferably a resin having high mechanical properties, particularly elastic modulus and tear strength, such as polyamide, Polyacetal, polyarylate, polycarbonate, polyphenylene ether, polyethylene terephthalate, polysulfone, polyether sulfone, polyphenylene sulfide, polybutylene terephthalate, polyether ether ketone, polyvinylidene fluoride, ethylene tetrafluoroethylene copolymer, tetrafluoroethylene-perfluoro Alkyl vinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyvinyl fluoride, acrylic resin, alkyl acrylate ester copolymer, polyester For example, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, polyvinylidene fluoride, and ethylenetetrafluoroethylene copolymer. In the present invention, one of these thermoplastic resins or a mixture thereof can be used.

  As an additive for the thermoplastic resin composition, a conductive substance can be added to impart conductivity. The conductive substance is a substance that can impart conductivity to the thermoplastic resin, and may be anything as long as it does not substantially change the properties of the thermoplastic resin. Carbon black particles, carbon fibers, carbon nanotubes, etc. Ion conductive polymers such as quaternary ammonium salts and polyether ester amides such as inorganic conductive powders and fibers may be used.

The electrical conductivity of this layer is preferably 1 × 10 ⁸ to 1 × 10 ¹² Ωcm in terms of volume resistivity, 6 to 15% by mass in the case of carbon black particles, and in the case of carbon-based inorganic conductive powders / fibers. 2 to 6% by mass, 1 to 6% by mass in the case of a quaternary ammonium salt, and 6 to 15% by mass in the case of an ionic conductive polymer can be exhibited by adding conductivity to the thermoplastic resin. is there.

  Other additives include antioxidants, heat stabilizers, heat aging inhibitors, anti-molding agents, plasticizers, crystal nucleating agents, fluidity improvers, ultraviolet absorbers, lubricants as long as the object of the present invention is not impaired. One or more usual additives such as mold release agents, colorants such as dyes and pigments, flame retardants, and flame retardant aids can be added.

(Layer made of cured resin composition)
The thickness of the hardened cured resin composition disposed on the inner peripheral surface of the endless belt made of the thermoplastic resin composition needs to be 0.5 μm or more and 5.0 μm or less. Since the belt for an image forming apparatus is stretched around several rollers and is driven to rotate, it is necessary to have bending resistance and be difficult to break. When the thickness of the hardened cured resin composition is less than 0.5 μm, the arithmetic average roughness of the inner peripheral surface of the layer made of the cured resin composition is the inner peripheral surface of the endless belt made of the thermoplastic resin composition. Susceptible to roughness. For this reason, it is difficult to make the arithmetic average roughness Ra of the inner peripheral surface of the layer made of the cured resin composition described in the next paragraph 0.1 μm or less. When the thickness of the hardened cured resin composition is larger than 5.0 μm, stress concentrates on the layer of the hardened cured resin composition when bent, but the hardened cured resin composition is brittle because of its high hardness. Therefore, cracking occurs due to long-term rotational driving. Preferably, it is 2.0 μm or less.

  The arithmetic average roughness Ra of the inner peripheral surface of the layer made of the cured resin composition is preferably 0.1 μm or less. When the arithmetic average roughness Ra of the inner peripheral surface of the layer made of the cured resin composition is larger than 0.1 μm, the belt surface has an opportunity to generate irregularities, and is manifested as vertical streaks on the image. . Furthermore, foreign matter adheres to the recesses on the inner peripheral surface, causing scratches on the stretched roller. Finally, the scratches on the rollers cause unevenness on the back surface of the image forming apparatus belt and surface irregularities.

  If the surface hardness of the layer is 0.30 GPa or more, particularly 0.35 GPa or more, there may be minute unevenness on the surface of the roller on which the belt for the image forming apparatus is stretched and supported by adhesion of foreign matter or image formation. Even if foreign matter such as metal powder or toner aggregate adheres to the back of the belt for the device, scratches are not formed in the circumferential direction of the roller surface due to long-term use. Further, the back surface of the belt for the image forming apparatus and the surface unevenness of the image forming apparatus are not easily generated because the back surface of the belt for the image forming apparatus cannot resist the influence of the unevenness, adhered matter, and the like. It is possible to obtain a simple image.

The cured resin composition includes melamine-based resins, urethane-based resins, alkyd-based resins, acrylic-based resins, and the like as organic materials, and alkoxylan / alkoxyzirconium-based and silicate-based materials as inorganic materials. . From the viewpoint of high hardness and coating properties, UV curable acrylic resins are particularly preferred. The trade name Desolite Z series (manufactured by JSR Co., Ltd.), the trade name Defensa 0P series (manufactured by Dainippon Ink Co., Ltd.) Examples include Reicure GA4100 series (manufactured by Jujo Chemical Co., Ltd.) and the like.
As an additive for the cured resin composition, a conductive substance can be added to impart conductivity. The conductive substance is a substance that can impart conductivity to the cured resin composition and may be anything as long as it does not essentially change the cured resin composition, and examples thereof include carbon black particles and metal oxides. The conductivity of this layer is preferably 1 × 10 ⁸ to 1 × 10 ¹² Ωcm in volume resistivity, 6 to 15% by mass in the case of carbon black particles, and 10 to 35% in the case of metal oxide. By adding%, it is possible to express desired conductivity.

  As other additives, as long as the object of the present invention is not impaired, an antioxidant, a heat stabilizer, a heat aging inhibitor, an antifungal agent, a plasticizer, a crystal nucleating agent, a fluidity improver, a release agent, One or more conventional additives such as colorants such as dyes and pigments, flame retardants, and flame retardant aids can be added.

Hereinafter, the present invention will be described in more detail using examples and comparative examples. The following examples describe specific embodiments that the present inventors think the best results have been obtained with respect to the present invention, and the present invention is limited only to these specific embodiments. is not.
In addition, the measuring methods, such as the film thickness of the layer which consists of a cured resin composition below, the arithmetic mean roughness Ra of the internal peripheral surface of the layer which consists of a cured resin composition, and surface hardness, are shown.

(Thickness measurement)
A belt for an image forming apparatus is cut into a 5 × 5 mm square to form a sample. The thickness was calculated by observing the polished sample using a scanning electron microscope (JSM-6300 type) manufactured by JEOL.
The number of observations for measuring the film thickness was 10 for each image forming apparatus belt, and the average value was taken as the film thickness of the image forming apparatus belt.

(Arithmetic mean roughness Ra)
For the calculation of roughness, using a surfcom 2800E manufactured by Tokyo Seimitsu Co., Ltd., using a diamond tip terminal of an arbitrary position of a belt for an image forming apparatus, a measurement length of 20 mm, a measurement speed of 0.6 mm / s, and a tip probe of 2 μmR. The arithmetic average roughness was calculated under the conditions based on JISB0651: 2001. The number of samples for roughness measurement was 10 for each image forming apparatus belt, and the average value was defined as the arithmetic average roughness Ra of the image forming apparatus belt.

(Surface hardness measurement)
Using a NanoIndenter DCM-SA type manufactured by MTS Systems Corporation, the surface hardness was measured under the conditions of an indentation speed of 10 nm / s and a maximum indentation amount of 1 μm. It was. The number of samples for measuring the surface hardness was 5 arbitrary positions for each image forming apparatus belt, and the average value was defined as the surface hardness of the image forming apparatus belt.

[Example 1]
(Endless belt)
A 50 μm film made of a polyvinylidene fluoride resin composition containing 1.8% by mass of an ionic conductive agent (tetrabutylammonium hydrogen sulfate, trade name: 98131, manufactured by Guangei Chemical Co., Ltd.) was produced by extrusion molding. An endless belt having a thickness of 100 μm was obtained from this film according to the method described in Example 1 of JP-A No. 2002-326287. The surface hardness of this endless belt was 0.19 GPa, and the arithmetic average roughness Ra of the inner peripheral surface of the endless belt was 0.21 μm μm.

(Layer formed on the inner peripheral surface of the endless belt)
Acrylic ultraviolet curable coating material containing dipentaerythritol hexaacrylate with 10 parts by mass of zinc antimonate iopropyl alcohol sol (trade name: Celnax CX-Z403M (Nissan Chemical)) as a conductive agent ( After mixing 50 parts by mass of trade name: Desolite Z6817B (manufactured by JSR), 40 parts by mass of methyl isobutyl ketone was added to obtain an ultraviolet curable resin composition. The UV curable resin composition is applied to the inner peripheral surface of the produced endless belt by a spray coating method, and after drying, a UV irradiator (trade name: UE06 / 81-3 (manufactured by Eye Graphic Co.)) is used. Then, an ultraviolet ray was irradiated so as to obtain an integrated light amount of 1200 mJ / cm ² to obtain a cured resin composition layer having a thickness of 1.3 μm. The film thickness can be controlled by the solid content concentration of the spray coat coating solution, the coating time, and the number of coatings after drying the coating solution solvent. In the present invention, the final coating time can be adjusted by adjusting the coating time. The film thickness of the cured resin composition layer was controlled.
The surface hardness of the layer formed on the inner peripheral surface of the endless belt was 0.36 GPa, and the arithmetic average roughness Ra of the inner peripheral surface was 0.08 μm.
Next, image evaluation was performed using the image forming apparatus shown in FIG. 1 using the image forming apparatus belt as an intermediate transfer belt. The driving roller 107 of the image forming apparatus has an outer surface layer made of ethylene propylene rubber, the stretching rollers 108 and 109 made of aluminum, and the secondary transfer counter roller 110 has an outer surface layer made of EPDM. The primary transfer rollers 111A, 111B, 111C, and 111D are made of foamed ethylene propylene rubber (EPM) on the outer surface.

  Using this image forming apparatus, an image with R = 142, G = 205, and B = 240 (magenta color 50%) is printed, and the number of prints on which an image defect such as a streak occurs is measured. It was evaluated. When a high-quality image can be obtained up to 150,000 sheets, it was determined that the image forming apparatus can be used as a high-quality full-color printer.

  When the image forming apparatus belt of this example was evaluated for images, even if 150,000 sheets or more were observed, no image defects such as streaks were observed on the image, and it was determined that the image forming apparatus belt was good.

[Example 2]
A 120 μm film made of a polyvinylidene fluoride resin composition containing 1.8% by mass of an ionic conductive agent (tetrabutylammonium hydrogen sulfate, trade name: 98131, manufactured by Guangei Chemical Co., Ltd.) was produced by extrusion molding. This film was cut into a predetermined length, and both ends of the film were overlapped and welded by an ultrasonic welding method using an ultrasonic welder to obtain an endless belt having a thickness of 120 μm. The surface hardness of this endless belt was 0.19 GPa, and the arithmetic average roughness of the inner peripheral surface of the endless belt was 0.28 μm.

(Layer formed on the inner peripheral surface of the endless belt)
The same ultraviolet curable resin composition as that used in Example 1 was applied to the inner peripheral surface of the produced endless belt by the dip coating method, and after drying, a UV irradiator (trade name: UE06 / 81-03 ( Using a graphic)) was irradiated with ultraviolet rays to obtain an integrated light amount of 3500 mJ / cm ² to obtain a cured resin composition layer having a thickness of 3.5 μm.

The surface hardness of the layer formed on the inner peripheral surface of the endless belt was 0.42 GPa, and the arithmetic average roughness Ra of the inner peripheral surface was 0.04 μm.
Next, as in Example 1, image evaluation was performed using the image forming apparatus of FIG. 1 using the image forming apparatus belt as an intermediate transfer belt. When the image forming apparatus belt of this example was evaluated for images, even if 150,000 sheets or more were observed, no image defects such as streaks were observed on the image, and it was determined that the image forming apparatus belt was good.

Example 3
(Endless belt)
An 80 μm endless belt made of a polyphenylene sulfide resin composition containing carbon black (trade name: Denka Black (manufactured by Denki Kagaku Kogyo)) was produced by cylindrical extrusion. In the cylindrical extrusion method of the present example, the blended pellet-shaped resin composition was melted by a single screw extruder, extruded from a cylindrical slit disposed at the tip of the extruder, and the above-mentioned by a cylindrical cooling mandrel. An endless belt can be obtained by cooling and solidifying the resin composition extruded into a cylindrical shape. The surface hardness of the endless belt was 0.31 GPa, and the arithmetic average roughness of the inner peripheral surface of the endless belt was 0.22 μm.

(Layer formed on the inner peripheral surface of the endless belt)
The same ultraviolet curable resin composition as used in Example 1 was applied to the inner peripheral surface of the produced endless belt by a spray coating method, and after drying, a UV irradiator (trade name: UE06 / 81-3) was applied. (Made by Eye Graphic Co., Ltd.) was used to irradiate ultraviolet rays so as to obtain an integrated light amount of 3000 mJ / cm ² to obtain a cured resin composition layer having a thickness of 2.5 μm.
The surface hardness of the layer formed on the inner peripheral surface of the endless belt was 0.40 GPa, and the arithmetic average roughness Ra of the inner peripheral surface was 0.06 μm.
Next, as in Example 1, image evaluation was performed using the image forming apparatus of FIG. 1 using the image forming apparatus belt as an intermediate transfer belt. When the image forming apparatus belt of this example was evaluated for images, even if 150,000 sheets or more were observed, no image defects such as streaks were observed on the image, and it was determined that the image forming apparatus belt was good.

(Example 4)
This example is an example of an image forming apparatus belt in which the surface hardness of the layer made of the cured resin composition formed on the inner peripheral surface of the endless belt of Example 1 is 0.34 GPa.

Example 1 except that the integrated light quantity of ultraviolet rays is changed to 600 mJ / cm ² in Example 1.
Similarly, a cured resin composition layer having a thickness of 1.3 μm was obtained.
The surface hardness of the layer formed on the inner peripheral surface of the endless belt was 0.34 GPa, and the arithmetic average roughness of the inner peripheral surface was 0.08 μm.

  Next, as in Example 1, image evaluation was performed using the image forming apparatus of FIG. 1 using the image forming apparatus belt as an intermediate transfer belt. In the image forming apparatus belt of this example, when image evaluation was performed, streaks were observed on the image of 120,000 sheets. Although it can be used as the belt for an image forming apparatus used in the image forming apparatus aiming at high quality and high durability of the present invention, it was found that the results of the durability test were slightly inferior to those of Examples 1 to 3.

  In this example, the surface hardness of the layer formed on the inner peripheral surface of the endless belt is slightly insufficient, and the rubber roller stretching the belt is attached with the wear debris of the primary transfer rubber roller, and the belt surface is uneven. Therefore, it is considered that an image defect has occurred. As a result of various studies by the present inventors, it was confirmed that the surface hardness of the layer formed on the inner peripheral surface of the endless belt is more preferably 0.35 GPa or more.

[Comparative Example 1]
This comparative example is an example relating to the belt for an image forming apparatus having no layer made of the cured resin composition formed on the inner peripheral surface of the endless belt of Example 1.
(Endless belt)
A 50 μm film made of a polyvinylidene fluoride resin composition containing an ionic conductive agent was produced by extrusion molding. An endless belt having a thickness of 100 μm was obtained from this film according to the method described in Example 1 of JP-A No. 2002-326287. The surface hardness of this endless belt was 0.19 GPa, and the arithmetic average roughness Ra of the inner peripheral surface of the endless belt was 0.21 μm.
(Layer formed on the inner peripheral surface of the endless belt)
None Next, as in Example 1, image evaluation was performed using the image forming apparatus of FIG. 1 using the image forming apparatus belt as an intermediate transfer belt. When the image of the image forming apparatus belt of this example was evaluated, streaks were observed on the image of 80000 sheets. The belt was judged to be unsuitable as an image forming apparatus belt used in an image forming apparatus aiming at high quality and high durability according to the present invention. The image defect in this comparative example is caused by the rubber roller that stretches the belt and the aluminum roller on which the wear debris of the primary transfer rubber roller is stretched. The cause was found to have occurred.

(Comparative Example 2)
This comparative example is an example relating to a belt for an image forming apparatus in which the film thickness of the layer made of the cured resin composition formed on the inner peripheral surface of the endless belt of Example 1 is 5.1 μm.

In Example 1, a cured resin composition layer having a thickness of 5.1 μm was obtained in the same manner as in Example 1 except that the cumulative amount of ultraviolet light was changed to 5000 mJ / cm ² .
The surface hardness of the layer formed on the inner peripheral surface of the endless belt was 0.42 GPa, and the arithmetic average roughness Ra of the inner peripheral surface was 0.08 μm.

  Next, as in Example 1, image evaluation was performed using the image forming apparatus of FIG. 1 using the image forming apparatus belt as an intermediate transfer belt. In the image forming apparatus belt of the present embodiment, when the image was evaluated, 40000 sheets of a plurality of point-like singular points (high density, low density points, and portions that are not uniform compared to the surroundings). An image was observed. The belt was judged to be unsuitable as an image forming apparatus belt used in an image forming apparatus aiming at high quality and high durability according to the present invention. Since the thickness of the layer formed on the inner peripheral surface of the endless belt in this comparative example is 5.1 μm, when used as a belt for an image forming apparatus, the layer is stretched on a roller and is rotated on the layer for a long time. It seems that stress was concentrated and fatigued. As a result of various studies by the present inventors, it has been found that the film thickness of the layer formed on the inner peripheral surface of the endless belt needs to be 5.0 μm or less.

(Comparative Example 3)
This comparative example is an example of the belt for an image forming apparatus in which the inner peripheral surface roughness Ra of the layer made of the cured resin composition formed on the inner peripheral surface of the endless belt of Example 1 is 0.11 μm.

In Example 1, a cured resin composition layer having a thickness of 1.3 μm was obtained in the same manner as in Example 1 except that the cumulative amount of ultraviolet light was changed to 1200 mJ / cm ² .
The surface hardness of the layer formed on the inner peripheral surface of the endless belt was 0.36 GPa, and the arithmetic average roughness Ra of the inner peripheral surface was 0.11 μm.

  Next, as in Example 1, image evaluation was performed using the image forming apparatus of FIG. 1 using the image forming apparatus belt as an intermediate transfer belt. In the image forming apparatus belt of this example, when image evaluation was performed, streaks were observed on the image of 100,000 sheets. The belt was judged to be unsuitable as an image forming apparatus belt used in an image forming apparatus aiming at high quality and high durability of the present invention. The image defect in this comparative example is that the arithmetic average roughness of the inner peripheral surface of the layer formed on the inner peripheral surface of the endless belt in this comparative example is 0.11 μm. This is presumed to be caused by the wear of the rubber roller and the primary transfer rubber roller that stretches the belt on the belt, and unevenness on the belt surface. As a result of various studies by the present inventors, it was confirmed that the arithmetic average roughness Ra of the inner peripheral surface of the layer formed on the inner peripheral surface of the endless belt is preferably 0.10 μm or less.

It is a figure explaining a process of an image forming apparatus. 1 is a schematic cross-sectional view of a belt for an image forming apparatus according to the present invention.

Explanation of symbols

100: electrostatic latent image unit 101: photosensitive drum 102: charging charger 103: optical writing device 104: developing device 106: intermediate transfer belt 107 to 110: rollers 111A to D: primary transfer roller 112: secondary transfer roller 113 : Transfer paper 114: Cleaning blade 115: Waste toner box 201: Endless belt 202 made of thermoplastic resin composition 202: Layer made of cured resin composition

Claims (4)

  On the inner peripheral surface of the endless belt made of the thermoplastic resin composition, a layer made of a cured resin composition having a hardness higher than that of the thermoplastic resin composition is formed with a thickness of 0.5 μm or more and 5.0 μm or less, and A belt for an image forming apparatus, wherein an arithmetic average roughness Ra of an inner peripheral surface of a layer made of the cured resin composition is 0.10 μm or less.   2. The belt for an image forming apparatus according to claim 1, wherein a surface hardness of the layer made of the cured resin composition is 0.35 GPa or more.   3. The belt for an image forming apparatus according to claim 1, wherein the layer made of the cured resin composition is made of a cured product of an ultraviolet curable acrylic resin.   An image forming apparatus comprising the image forming belt according to claim 1.

Images