JP2008040139A - Endless belt and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an endless belt capable of forming an image of high quality for a long period regardless of mounting conditions of the endless belt and image forming conditions etc., and to provide an image forming apparatus equipped with the endless belt. <P>SOLUTION: There are provided the endless belt 1A including a belt base layer 2, a foamed elastic layer 3A formed on the outer peripheral surface of the belt base layer 2, and a surface layer 4A formed on the outerperipheral face of the formed elastic layer 3A and the image forming apparatus including the endless belt 1A. The endless belt 1A includes the foamed elastic layer 3A containing a cell 7 and therefore, even if the belt base layer 2 is formed of a resin composition and also, even if the mounting conditions of the endless belt 1A and the image forming conditions etc., are not set in details, the foamed elastic layer 3A efficiently absorbs the change in the abutting area of the endless belt 1A and a body to be abutted and abutting pressure etc., for a long period. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an endless belt and an image forming apparatus, and more particularly to an endless belt capable of forming a high-quality image over a long period of time and an image forming apparatus including the endless belt.

  In the electrophotographic image forming apparatus, an endless belt formed of a thermoplastic resin or the like is used instead of or in addition to the metal drum body or the elastic roller. Examples of such an endless belt include a transfer belt, an intermediate transfer belt, a transfer conveyance belt, a conveyance belt, a development belt, a photosensitive belt, and a fixing belt. These endless belts are stretched around a plurality of support rollers in a state where tension is always applied, and travel on an endless track.

As such an endless belt, for example, “obtained by cutting a tubular film of polycarbonate blended with conductive carbon into a predetermined length in a direction perpendicular to the axial direction, the surface electric resistance of each part of the film is obtained. A seamless semiconductive belt characterized in that it is in the range of 10 ⁵ to 10 ¹³ Ω / □ and the ratio of the minimum value to the maximum value of the surface electrical resistance is in the range of 0.01 or more. (Refer to Patent Document 1.) In addition, “in a fixing / pressurizing belt for fixing an electrostatic image transferred to a transfer object, a belt body made of polyamideimide resin and a surface of the belt body covered with silicone rubber Examples thereof include a fixing / pressurizing belt characterized by forming a layer (see Patent Document 2).

  In order to form a high-quality image in an image forming apparatus using an endless belt, in addition to the endless belt traveling stably between a plurality of support rollers, when the endless belt travels on an endless track, It is necessary to attach the endless belt to a predetermined position in the image forming apparatus so as to contact or press contact with the contacted body with a desired contact area and contact pressure.

  However, since the endless belt described in Patent Document 1 is usually formed in a single-layer structure with a resin material as in Example 1 or the like, it is basically in line contact with the contacted object. Abut. Therefore, the endless belt is usually attached to the image forming apparatus so as to abut or press against the abutted body with a desired abutting area and abutting pressure when traveling on an endless track. It ’s difficult. For this reason, when the endless belt is mounted on the image forming apparatus, it is necessary to set the dimensional accuracy of the endless belt and the support roller, the mounting conditions such as the mounting method of the endless belt, and the like in detail. Furthermore, even if the endless belt can be attached to the image forming apparatus so as to abut or press against the abutted body with a desired abutting area and abutting pressure, the endless belt described in Patent Document 1 is electrically conductive. Since this is a polycarbonate tube film containing functional carbon, when the image forming conditions such as the environment during image formation change, the endless belt is stretched around the support roller in a state where tension is applied over a long period of time. Then, the contact area and the contact pressure adjusted as desired are gradually changed by the tension change due to stretching of the endless belt and / or meandering traveling, etc., and as a result, a high quality image can be obtained over a long period of time. Sometimes it cannot be formed.

  The fixing / pressurizing belt described in Patent Document 2 has a silicone rubber coating layer formed on the surface of a belt body made of polyamideimide resin. The silicone rubber coating layer has a thickness of about 50 to 100 μm (patent) Since it is thinly formed on the second page, right column, lines 26 to 27 of Document 2, the silicone rubber coating layer can exhibit an effect that improves the characteristics of the belt body made of polyamideimide resin. As a result, it is expected that the fixing / pressurizing belt described in Patent Document 2 cannot sufficiently solve the above problem.

JP-A-3-89357 Japanese Utility Model Publication No. 6-397

  An object of the present invention is to provide an endless belt capable of forming a high-quality image over a long period of time and an image forming apparatus including the endless belt.

As means for solving the problems,
Claim 1 is an endless belt comprising a belt base layer, a foam elastic layer formed on the outer peripheral surface of the belt base layer, and a skin layer formed on the outer peripheral surface of the foam elastic layer,
Claim 2 is the endless belt according to claim 1, comprising a coat layer on an outer peripheral surface of the skin layer.
A third aspect of the present invention is an image forming apparatus including the endless belt according to the first or second aspect.

  Since the endless belt according to the present invention includes the foam elastic layer on the outer peripheral surface of the belt base layer, even if the belt base layer is formed of a resin composition, the endless belt mounting conditions, image forming conditions, etc. Even if it is not set in detail, the foam elastic layer can effectively absorb changes in the contact area and contact pressure between the endless belt and the contacted body over a long period of time. Therefore, according to the present invention, an endless belt capable of forming a high-quality image over a long period of time can be provided.

  Further, according to the present invention, since the endless belt according to the present invention is provided, an image forming apparatus capable of forming a high-quality image for a long period of time can be provided.

  Hereinafter, an endless belt as an example of the present invention will be described with reference to the drawings. As shown in FIGS. 1 and 2, the endless belt 1A is formed on the belt base layer 2, the foam elastic layer 3A formed on the outer peripheral surface of the belt base layer 2, and the outer peripheral surface of the foam elastic layer 3A. And 4 A of skin layers.

  As shown in FIG. 1, the belt base layer 2 is formed in a ring shape from a resin composition described later. The belt base layer 2 has a single layer structure as shown in FIGS. 1 and 2, but the belt base layer 2 may have a multilayer structure in which two or more layers are laminated. The thickness of the belt base layer 2 is not particularly limited, but is usually preferably, for example, 0.03 to 1 mm, more preferably 0.04 to 0.2 mm, and about 0.05 to 0.15 mm. Is particularly preferred. If the thickness of the belt base layer 2 is less than 0.03 mm, the mechanical strength of the belt base layer 2 and the endless belt 1A may decrease. On the other hand, if the thickness exceeds 1 mm, the flexibility of the belt base layer 2 and the endless belt 1A may be reduced. May be inferior in durability and durability. The width and inner peripheral diameter of the belt base layer 2 are arbitrarily set according to the use of the endless belt 1A, that is, the position (component) disposed in the image forming apparatus, the interval between the stretched rollers, and the like. Is done. For example, the width of the belt base layer 2 is 200 to 350 mm, and the inner peripheral diameter is 350 to 2,500 mm.

  The foam elastic layer (hereinafter sometimes referred to as an elastic layer) 3A is formed on the outer peripheral surface of the belt base layer 2 by a rubber composition to be described later. The elastic layer 3A is preferably formed on the entire outer peripheral surface of the belt base layer 2 as shown in FIGS. 1 and 2, but depending on the use of the endless belt 1A, etc. It may be formed in part.

  As shown in FIG. 2, the elastic layer 3A only needs to have cells 7 (not shown in FIG. 1) inside and / or near the boundary between the elastic layer 3A and the skin layer 4A. As shown in FIG. 2, the cell 7 in the layer 3A may be in a state where it does not contact or communicate with another cell 7 (referred to as an independent cell state). 7 may be in a state of being in contact with or in communication (referred to as a communication cell state), or a state in which the independent cell state and the communication cell state coexist. The cells 7 may be uniformly dispersed or scattered in the elastic layer 3A.

  When the elastic layer 3A has the cells 7, the hardness and the like of the elastic layer 3A can be easily adjusted. As a result, even if the belt base layer 2 is formed of the resin composition, The endless belt is not required to set in detail the mounting conditions of the belt 1A (for example, the tension applied to the endless belt 1A, the contact area between the endless belt 1A and the contacted body, the contact pressure, etc.) and the image forming conditions. Changes in the contact area and contact pressure between 1A and the contacted body can be effectively absorbed over a long period of time.

It is preferable that the physical properties such as the size of the cell 7 are determined according to the use of the endless belt 1A and / or so that the Asker C hardness of the elastic layer 3A is within a range described later. For example, the cell 7 preferably has an average cell diameter of 100 to 800 μm, particularly preferably 200 to 400 μm. When the cell 7 has an average cell diameter within the above range, the endless belt 1A effectively absorbs changes in the contact area and contact pressure between the endless belt 1A and the contacted body over a long period of time. can do. The average cell diameter of the cell 7 is the maximum diameter in the cell 7 existing in the observation field when an area of about 2 mm ^{2 on} the surface or cross section of the elastic layer 3A is observed with an electron microscope (the maximum length in the opening of each cell). ) For the arithmetic average.

The cell 7 preferably has a ratio (r _max / r _min ) of the maximum cell diameter r _max to the minimum cell diameter r _min of 1.5 or less, more preferably 1.45 or less. Particularly preferred is 4 or less. When the cell 7 has r _max / r _min in the above range, the physical properties of the elastic layer 3A become uniform, and when the endless belt 1A is formed, the contact area and the contact pressure between the endless belt 1A and the contacted body Such changes can be absorbed more effectively over a long period of time. The lower limit of r _max / r _min is preferably 1, but the object of the present invention can be sufficiently achieved even at about 1.2. The ratio of the maximum cell diameter to the minimum cell diameter (r _max / r _min ) is determined by observing the surface of the elastic layer 3A or a region of about 2 mm ^{2 on} the cross section with an electron microscope or the like, and in a plurality of cells existing in the observation field, The maximum length at the opening of each cell is measured, and the cell diameter ratio of the cell having the maximum cell diameter r _max to the cell having the minimum cell diameter r _min (r It can be obtained by calculating _max / r _min ). Note that observation is preferably performed in a plurality of regions, for example, three regions, and averaged.

The cell 7 preferably has a standard deviation σ of the cell diameter of 0.10 or less, more preferably 0.07 or less, and particularly preferably 0.05 or less. When the cell diameter has the standard deviation σ within the above range, the physical properties of the elastic layer 3A become uniform. When the endless belt 1A is used, the contact area between the endless belt 1A and the contacted body, the contact pressure, etc. The change can be absorbed more effectively over a long period of time. Here, the standard deviation σ of the cell diameter can be obtained by an ordinary method. Specifically, an area of about 2 mm ^{2 on} the surface or cross section of the elastic layer 3A is observed with an electron microscope or the like, the maximum length at the opening of each cell 7 existing in the observation field is measured, and the maximum measured The standard deviation σ can be obtained with the length as the cell diameter of the cell. Note that the observation is performed in a plurality of regions, for example, three regions, and preferably, the surface of the elastic layer 3, the cut surface cut along the axial direction of the elastic layer 3, and the thickness direction of the elastic layer 3 Three observation regions are arbitrarily selected from the cut surfaces cut along the line.

The cell 7 is preferably 0.1 to 0.6 mm in distance (hereinafter sometimes referred to as inter-cell distance) with other cells 7 existing in the vicinity, for example 0.1 to 0 mm. Particularly preferred is 3 mm. When the inter-cell distance is within the above range, when the endless belt 1A is used, changes in the contact area and the contact pressure between the endless belt 1A and the contacted body can be effectively absorbed over a long period of time. it can. The distance of the cell 7 is that a region of about 2 mm ^{2 on} the surface or cross section of the elastic layer 3A is observed with an electron microscope, and a plurality of cells 7 existing in the observation field are present around a specific cell 7 and its surroundings. It can be obtained by an arithmetic average of distances between centers with a plurality of cells.

  The shape of the cell 7 is not particularly limited. For example, as shown in FIG. 2, the cell 7 may be substantially spherical, oval or indeterminate, and a plurality of cells communicate with each other. It may be tubular.

  The elastic layer 3A only needs to have a plurality of the cells 7, but the Asker C hardness is preferably 10-50. If the Asker C hardness of the elastic layer 3A is within the above range, even if the belt base layer 2 is formed of the resin composition, the mounting conditions and image forming conditions of the endless belt 1A are not set in detail. Even so, the elastic layer 3A can effectively absorb changes in the contact area and contact pressure between the endless belt 1A and the contacted body over a long period of time. The Asker C hardness of the elastic layer 3A is 10 to 30 in that the elastic layer 3A can absorb changes such as the contact area and the contact pressure over a longer period of time as desired. Is more preferable, and it is especially preferable that it is 10-20. The Asker C hardness of the elastic layer 3 </ b> A can be measured according to JIS K6253 in a state where it is formed on the outer peripheral surface of the belt base layer 2. The Asker C hardness of the elastic layer 3A is, for example, by selecting the type of rubber and foaming agent contained in the rubber composition forming the elastic layer 3A and / or by changing the content thereof. Can be adjusted.

The elastic layer 3A preferably has a density of 0.1 to 0.6 g / cm ³ . When the density of the elastic layer 3A is within the above range, when the endless belt 1A is used, the contact area and contact pressure between the endless belt 1A and the contacted body are prevented from being lowered due to the bending of the endless belt 1A. can do. The density of the elastic layer 3A is more preferably 0.2 to 0.5 g / cm ³ in that the contact area, the contact pressure, and the like can be prevented as desired. It is particularly preferably ³ to 0.4 g / cm ³ . For the density of the elastic layer 3A, a test piece obtained by cutting out the elastic layer 3 formed on the endless belt 1A or a test piece formed by molding a rubber composition similar to the elastic layer 3 under the same conditions is prepared. It can be measured by a conventional method using a scale. As shown in FIG. 2, when the elastic layer 3 and the skin layer 4 are integrally formed, the density of the elastic layer 3 is considered that the elastic layer 3A and the skin layer 4A are one layer. The density of time.

If the conductivity is required to the endless belt 1A, the elastic layer 3A, the volume resistivity ([rho] v) is preferably in the range of ^{1 × 10 9 ~1 × 10 13} Ω · cm, 1 × 10 10 ~ It is particularly preferably 1 × 10 ¹² Ω · cm. When the volume resistivity (ρv) is within the above range, a high-quality image can be formed when the endless belt 1A is used in an image forming apparatus. The volume resistivity (ρv) can be measured by a volume resistance measuring device (manufactured by Mitsubishi Chemical Corporation, trade name: Hirosta-UP, probe used: URS).

  The thickness of the elastic layer 3A is not particularly limited, but usually, for example, it is preferably 0.1 to 3 mm, more preferably 0.5 to 2 mm, and about 1 to 1.5 mm. Particularly preferred. When the thickness of the elastic layer 3A is less than 0.1 mm, the cells 7 cannot be sufficiently formed, and the above-described effect due to the formation of the elastic layer 3A may not be sufficiently exhibited, while 3 mm If the thickness exceeds the nip width, the nip width with the contacted body (the width of the contact portion) is too large, and the contact portion with the contacted body may be wrinkled. Further, when the endless belt 1A is mounted on the image forming apparatus as a transfer conveyance belt, a nip mark between the contacted body and the endless belt 1A may remain on the sheet conveyed by the endless belt 1A.

  The skin layer 4A is formed integrally with the elastic layer 3A on the outer peripheral surface of the elastic layer 3A by a rubber composition to be described later. As shown in FIG. 2, the skin layer 4A is preferably formed on the entire outer peripheral surface of the elastic layer 3A. However, depending on the use of the endless belt 1A, the skin layer 4A is formed on a part of the outer peripheral surface of the elastic layer 3A. It may be formed.

  This skin layer 4A is basically the same as the elastic layer 3A except that the cell 7 is not provided. However, the Asker C hardness of the skin layer 4A depends on the Asker C hardness of the elastic layer 3A and is slightly larger than the elastic layer 3A, for example, preferably 15 to 55. When the Asker C hardness of the skin layer 4A is within the above range, the skin layer 4A functions in the same manner as the elastic layer 3A, and elastically changes changes in the contact area and contact pressure between the endless belt 1A and the contacted body. The layer 3A and the skin layer 4A can absorb effectively over a long period of time. The Asker C hardness of the skin layer 4A is 15 in that the elastic layer 3A and the skin layer 4A can absorb changes such as the contact area and the contact pressure over a longer period of time as desired. More preferably, it is -35, and it is especially preferable that it is 15-25.

When the endless belt 1A is required to have conductivity, the skin layer 4A may not have conductivity as long as the skin layer 4A can maintain the conductivity of the elastic layer 3A. The rate (ρv) is preferably 1 × 10 ⁹ to 1 × 10 ¹³ Ω · cm, and particularly preferably 1 × 10 ¹⁰ to 1 × 10 ¹² Ω · cm. When the volume resistivity (ρv) is within the above range, a high-quality image can be formed as desired when the endless belt 1A is used in an image forming apparatus. The volume resistivity (ρv) can be measured by the above method.

  Although the thickness of 4 A of skin layers is not specifically limited, Usually, it is preferable that it is 0.01-1 mm, for example, and it is especially preferable that it is about 0.1-0.5 mm. If the thickness of the skin layer 4A is less than 0.01 mm, the surface of the skin layer 4A may not be adjusted smoothly due to the cells 7 opening on the surface of the elastic layer 3A, whereas it exceeds 1 mm. Then, the characteristics of the elastic layer 3A may be greatly impaired by the skin layer 4A.

  As shown in FIG. 2, the endless belt 1A includes an elastic layer 3A having cells 7 and a skin layer 4A having no cells 7. Preferably, the skin layer 4A maintains the Asker C hardness of the elastic layer 3A. Since the belt base layer 2 is formed of a resin composition to be described later, the mounting conditions and image forming conditions of the endless belt 1A are not set in detail. However, it is possible to effectively absorb changes such as the contact area and the contact pressure between the endless belt 1A and the contacted object over a long period of time.

  Next, an endless belt as another example of the present invention will be described with reference to the drawings. As shown in FIG. 3, the endless belt 1B includes a belt base layer 2, a foam elastic layer 3B formed on the outer peripheral surface of the belt base layer 2, and a foam elastic layer on the outer peripheral surface of the foam elastic layer 3B. 3B and a skin layer 4B formed separately, and a coat layer 5 formed on the outer peripheral surface of the skin layer 4B. The belt base layer 2 of the endless belt 1B is basically the same as the belt base layer 2 of the endless belt 1A. The foam elastic layer 3B and the skin layer 4B of the endless belt 1B are endless except that they are individually formed. This is basically the same as the foam elastic layer 3A and the skin layer 4A of the belt 1A.

In addition, when the skin layer 4B is formed separately from the foam elastic layer 3B, the skin layer 4B preferably has a density of 1.0 to 2.0 g / cm ³ . When the density of the skin layer 4B is within the above range, the skin layer 4B and the elastic layer 3B cooperate to form the endless belt 1B, so that the endless belt 1B is brought into contact with the endless belt 1B due to bending or the like. It is possible to prevent a decrease in the contact area with the body and the contact pressure. The density of the skin layer 4B is more preferably 1.0 to 1.5 g / cm ^{3 in} that the reduction of the contact area and the contact pressure can be prevented as desired. Particularly preferred is 0 to 1.2 g / cm ³ . The density of the skin layer 4B can be measured by the above method.

  The coat layer 5 improves toner releasability and non-adhesiveness to a contacted body such as an image carrier. As shown in FIG. 3, the coat layer 5 is preferably formed on the entire outer peripheral surface of the skin layer 4B with the material described later. However, depending on the use of the endless belt 1B, the outer peripheral surface of the skin layer 4B It may be formed in a part of. Since the coat layer 5 is brought into contact or pressure contact with the contacted body, the plane is preferably smooth.

  The thickness of the coat layer 5 is not particularly limited, but usually, for example, it is preferably 1 to 100 μm, more preferably 1 to 50 μm, and particularly preferably 1 to 20 μm. When the thickness of the coat layer 5 is in the above range, not only the toner releasability and the non-adhesiveness to the contacted body can be improved, but the properties of the foam elastic layer 3B and the skin layer 4B can be improved by the coat layer 5. Is not greatly impaired.

  As shown in FIG. 3, the endless belt 1B includes a belt base layer 2, a foam elastic layer 3B, a skin layer 4B, and a coat layer 5. Preferably, the skin layer 4B maintains the Asker C hardness of the elastic layer 3B. Since the belt base layer 2 is formed of a resin composition to be described later, the mounting conditions and image forming conditions of the endless belt 1B are not set in detail. However, changes in the contact area and contact pressure between the endless belt 1B and the contacted body can be effectively absorbed over a long period of time.

  The resin composition forming the belt base layer 2 of the endless belts 1A and 1B (hereinafter sometimes referred to as the endless belt 1) has a certain degree of strength and is flexible enough to withstand repeated deformation. The resin composition is preferably a rich resin or a resin composition containing a plurality of types of resins. Examples of the resin contained in such a resin composition include polyamideimide resin, polyimide resin, polyamide resin, and aramid resin. Polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), cross-linked polyester resin, fluorine resin, polysulfone resin, polyethersulfone resin, polycarbonate resin, polyetheretherketone Resin (PEEK), Epoxy resin, Melamine Butter, and the like can be mentioned. Among these, polyamideimide resin, polyimide resin, and polyamide resin are preferable. Particularly, polyamideimide resin and further aromatic polyamideimide resin have a good balance of mechanical properties such as strength, flexibility, dimensional stability, and heat resistance. It is excellent in that the endless belt 1 can be stretched on a support roller as desired over a long period of time.

  The aromatic polyamideimide resin can be produced by a diisocyanate method in which a tricarboxylic acid anhydride and a diisocyanate compound are reacted, and is excellent in terms of availability of raw materials, reactivity, and a small amount of byproducts. In addition, the aromatic polyamideimide resin can be produced using a diamine compound instead of the diisocyanate compound. An aromatic polyamideimide resin obtained using a diamine compound has a high Young's modulus and is suitable as a resin contained in the resin composition forming the endless belt 1. As the solvent used in the polycondensation reaction for synthesizing the aromatic polyamideimide resin, a polar solvent is preferable in terms of solubility, and an aprotic polar solvent is particularly preferable in consideration of reactivity. The tricarboxylic acid anhydride is preferably an aromatic tricarboxylic acid anhydride, and the diisocyanate compound is preferably an aromatic diisocyanate compound.

  In addition to the above properties, the aromatic polyamideimide resin in which part of the tricarboxylic acid anhydride is replaced with tetracarboxylic dianhydride to increase the imide bond is excellent in moisture resistance. The aromatic polyamideimide resin can be easily synthesized by reacting in an appropriate solvent under normal pressure and at normal temperature or under heating. Examples of the tetracarboxylic dianhydride include pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, and 3,3 ′, 4,4′-biphenyltetracarboxylic acid. Dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,2′-bis (3,4-dicarboxyphenyl) ) Propane dianhydride, bis (3,4-dicarboxyphenyl) sulfonic dianhydride, perylene-3,4,9,10-tetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether And dianhydrides, ethylenetetracarboxylic dianhydrides, and derivatives thereof.

  When the endless belt 1 is required to have conductivity, a conductivity imparting agent is added to the resin composition to obtain a conductive resin composition. Examples of the conductivity imparting agent include various carbon blacks, graphite powders, powders of metals or alloys, and the like. Among these, carbon black is preferable in that the particle size, conductivity, affinity with resin, and the like are excellent in a balanced manner. The addition amount of the conductivity imparting agent may be appropriately adjusted depending on the conductivity and particle size of the conductivity imparting agent, the conductivity required for the endless belt 1, and the like. It is preferable that it is 1-25 mass% with respect to 100 mass% of mass. Examples of the endless belt that requires electrical conductivity include a transfer belt, an intermediate transfer belt, a transfer conveyance belt, a conveyance belt, a development belt, and a photosensitive belt.

  In addition to the resin or the resin and the conductivity imparting agent, the resin composition and the conductive resin composition include, for example, a silicone compound, a fluorine organic compound, a coupling agent, a lubricant, an antioxidant, a plasticizer, Various additives such as a colorant, an antistatic agent, an anti-aging agent, a reinforcing filler, a reaction aid, a reaction inhibitor, and other resins and solvents may be contained.

  The resin composition and the conductive resin composition can be prepared using, for example, a mixing roll, a pressure kneader, an extruder, a three roll, a homogenizer, a ball mill, a bead mill, and the like.

  The rubber composition for forming the elastic layers 3A and 3B (hereinafter sometimes referred to as the elastic layer 3) of the endless belt 1 contains rubber, a foaming agent, and various additives as required. The rubber may be a composition, and examples of the rubber include silicone or silicone-modified rubber, nitrile rubber, ethylene propylene rubber (including ethylene propylene diene rubber), styrene butadiene rubber, butadiene rubber, isoprene rubber, natural rubber, acrylic rubber, Examples include chloroprene rubber, butyl rubber, epichlorohydrin rubber, urethane rubber, and fluorine rubber. Silicone or silicone-modified rubber and urethane rubber are easy to mold and form images from heat resistance, durability, and residual strain resistance. This is preferable in that it can sufficiently withstand high-speed operation of the apparatus.

  The foaming agent may be any foaming agent conventionally used for foamed rubber. Examples of the inorganic foaming agent include sodium bicarbonate and ammonium carbonate. Examples of the organic foaming agent include diazoamino derivatives, azonitri derivatives, azo And organic azo compounds such as dicarboxylic acid derivatives. Usually, an inorganic foaming agent is used when forming a continuous cell in rubber, and an organic foaming agent is used when forming an independent cell. As the various additives, various additives conventionally used in rubber compositions can be used without particular limitation. When the endless belt 1 is required to have conductivity, a conductivity imparting agent similar to the conductivity imparting agent contained in the resin composition forming the belt base 2 is added.

  Among the rubber compositions, a foamed silicone rubber-based composition and a foamed urethane rubber-based composition that can form a cell in an independent cell state are preferably used for forming the elastic layer 3. In particular, the foamed silicone rubber-based composition capable of forming a cell in an independent cell state is excellent in heat resistance, durability, resistance to residual strain, etc., and is suitable for a high-speed operation of an image forming apparatus. It is. As such a foamed silicone rubber composition, an addition reaction type foamed silicone rubber composition is particularly preferred.

  The addition reaction type foamed silicone rubber composition comprises a vinyl group-containing silicone raw rubber, a silica-based filler, a foaming agent, an addition reaction crosslinking agent, an addition reaction catalyst, a reaction control agent, and an organic peroxide as required. Contains a crosslinking agent and various additives.

  Examples of the vinyl group-containing silicone raw rubber include millable silicone rubber and heat-crosslinked silicone rubber (HTV: High Temperature Vulcanizing). These vinyl group-containing silicone raw rubbers have the property that a foaming agent, a crosslinking agent, etc. can be easily kneaded with a roll mill or the like in a later step, and may be used alone or in combination of two or more. it can.

Examples of the silica-based filler include a fumed silica or a precipitated silica having a reinforcing property, and a surface having a high reinforcing effect that is surface-treated with a silane coupling agent represented by a general formula RSi (OR ′) _3. A treated silica-based filler is preferred. Here, R in the general formula is a glycidyl group, vinyl group, aminopropyl group, methacryloxy group, N-phenylaminopropyl group, mercapto group or the like, and R ′ in the general formula is a methyl group or an ethyl group. . The silane coupling agent represented by the general formula can be easily obtained, for example, as trade names “KBM1003” and “KBE402” manufactured by Shin-Etsu Chemical Co., Ltd. Such a silica-based filler surface-treated with a silane coupling agent can be obtained by treating the surface of the silica-based filler according to a conventional method. The compounding amount of the silica-based filler is preferably 5 to 100 parts by mass with respect to 100 parts by mass of the vinyl group-containing silicone raw rubber.

  The foaming agent is preferably the organic foaming agent in that it can form a cell in an independent cell state. Specifically, for example, azodicarbonamide, azobis-isobutyronitrile and the like can be used. Compounds are preferably used. In particular, dimethyl-1,1'-azobis (1-cyclohexanecarboxylate) is preferably used. The content of the foaming agent varies depending on the type of foaming agent, but it is preferable to adjust the Asker C hardness of the elastic layer 3 to be within the above range. Specifically, for example, 1 to 10 parts by mass, particularly 1 to 7 parts by mass is preferable with respect to 100 parts by mass of the vinyl group-containing silicone raw rubber. If the content of the foaming agent is less than 1 part by mass, sufficient cells may not be formed in the formed elastic layer 3, while if it exceeds 10 parts by mass, the foamed silicone rubber is in a form. May not be maintained, and the mechanical strength of the elastic layer 3 may be reduced. When dimethyl-1,1′-azo-bis (1-cyclohexanecarboxylate) is selected as the foaming agent, the content thereof is 3 to 5 parts by mass with respect to 100 parts by mass of the vinyl group-containing silicone raw rubber. Is particularly good.

  As the addition reaction crosslinking agent, for example, a known organohydrogenpolysiloxane can be used as an addition reaction type crosslinking agent having two or more SiH groups (SiH bonds) in one molecule. The organohydrogenpolysiloxane may be linear, cyclic, or branched. The compounding amount of the organohydrogenpolysiloxane is preferably 0.01 to 20 parts by mass with respect to 100 parts by mass of the vinyl group-containing silicone raw rubber.

  The addition reaction catalyst includes, for example, a simple substance of Group 9 or 10 of the periodic table and a compound thereof, and more specifically, particulate platinum adsorbed on a carrier such as silica, alumina, or silica gel. Metals, platinum chloride, chloroplatinic acid, chloroplatinic acid hexahydrate and olefin or divinyldimethylpolysiloxane complexes, platinum-based catalysts such as chloroplatinic acid hexahydrate alcohol solutions, palladium catalysts, rhodium catalysts, etc. Can be mentioned. The addition amount of these addition reaction catalysts is sufficient as the catalyst amount, and is usually 1 in terms of the total amount of addition reaction type foamed silicone rubber composition in terms of the metal amount of Group 9 or Group 10 of the Periodic Table. It is good that it is -1,000 ppm, and it is especially good that it is 10-500 ppm. When the compounding amount of the addition reaction catalyst is less than 1 ppm in terms of the group 9 or 10 metal content of the periodic table, the crosslinking reaction of the vinyl group-containing silicone raw rubber does not proceed sufficiently, and the vinyl group-containing silicone raw rubber On the other hand, if it exceeds 1,000 ppm, the ability to accelerate the crosslinking reaction of the vinyl group-containing silicone raw rubber is not improved, and the economic efficiency may be lowered.

  As the reaction control agent, a known reaction control agent can be used without particular limitation, and examples thereof include methylvinylcyclotetrasiloxane, acetylene alcohols, siloxane-modified acetylene alcohol, and hydroperoxide. The compounding amount of the reaction control agent is preferably 0.1 to 2 parts by mass with respect to 100 parts by mass of the vinyl group-containing silicone raw rubber.

  The organic peroxide cross-linking agent can be used alone to cross-link vinyl group-containing silicone raw rubber, but if used in combination as an auxiliary cross-linking agent for an addition reaction cross-linking agent, the physical properties of the silicone rubber, such as strength and strain, can be improved. improves. Examples of the organic peroxide crosslinking agent include benzoyl peroxide, bis-2, -dichlorobenzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-bis ( t-butylperoxy) hexane and the like. The compounding amount of the organic peroxide crosslinking agent is preferably 0.3 to 10 parts by mass with respect to 100 parts by mass of the vinyl group-containing silicone raw rubber.

  The various additives include, for example, carbon black such as acetylene black, furnace black, channel black, filler such as calcium carbonate, colorant, heat resistance improver, flame retardant improver, heat conductivity improver, etc. Agents, mold release agents, alkoxysilanes, diphenylsilanediols, carbon functional silanes, dispersants such as both-end silanol-blocked low molecular siloxanes, and crushed quartz, diatomaceous earth, etc. that can adjust the hardness of the resulting rubber Non-reinforcing silica is exemplified. These various additives are blended in a desired blending amount.

  The addition reaction type foamed silicone rubber composition has a conductivity imparting agent similar to the conductivity imparting agent contained in the resin composition forming the belt base 2 when the endless belt 1 requires conductivity. Added. The addition amount of the conductivity-imparting agent may be appropriately adjusted depending on the conductivity and particle size of the conductivity-imparting agent, the conductivity required for the endless belt 1, and the like. It is preferable that it is 1-25 mass% with respect to the total mass of a thing.

  As the silicone rubber composition containing the vinyl group-containing silicone raw rubber, the silica filler, and the various additives, for example, trade names “KE series” and “KEG series” manufactured by Shin-Etsu Chemical Co., Ltd. can be easily used. It can be obtained.

  The rubber composition is, for example, several minutes to several hours, preferably 5 until it is uniformly mixed using a rubber kneader such as a two-roll, three-roll, roll mill, Banbury mixer, dough mixer (kneader) or the like. It is obtained by kneading at room temperature or under heating for 1 minute to 1 hour.

  The rubber composition for forming the skin layers 4A and 4B (hereinafter sometimes referred to as the skin layer 4) is basically the same as the rubber composition for forming the elastic layer 3.

  The material for forming the coat layer 5 is not particularly limited. However, since the endless belt 1 is in contact with or pressed against the contacted body, it is preferable that the material is not easily permanently deformed. Resin, modified alkyd resin such as phenol modified / silicone modified, oil-free alkyd resin, acrylic resin, silicone resin, epoxy resin, fluororesin, phenol resin, polyamide resin, urethane resin, polyamideimide resin and mixtures thereof Can be mentioned.

  A method for manufacturing the endless belt 1 according to the present invention will be described. In order to manufacture the endless belt 1, first, the belt base layer 2 is formed by a known forming method. For example, when a thermoplastic resin is selected as the resin contained in the resin composition forming the belt base layer 2, when a thermosetting resin is selected as the resin by centrifugal molding, extrusion molding, injection molding, etc. The belt base layer 2 can be formed by centrifugal molding, RIM molding, or the like. Among these molding methods, centrifugal molding is preferable in that it can be applied regardless of the material and is excellent in thickness accuracy.

  When the belt base layer 2 is formed by centrifugal molding, the resin composition forming the belt base layer 2 is preferably adjusted to have a viscosity at molding of 50,000 mPa · s or less. When the viscosity exceeds 50,000 mPa · s, it may be difficult to produce the belt base layer 2 having a uniform thickness. The lower limit of the viscosity of the resin composition is not particularly limited, but is preferably 10 mPa · s. When the viscosity of the resin composition is out of the above range, the viscosity of the resin composition can be adjusted within the above range by adjusting the amount of the solvent added.

  According to centrifugal molding, a fluid resin composition is injected into a cylindrical mold, and the mold is rotated to uniformly mold a film-shaped molded body on the inner peripheral surface of the mold by centrifugal force, and the solvent is removed by drying. Thus, the belt base layer 2 is manufactured. Various metal pipes can be used for the mold. As a suitable mold, the inner peripheral surface of the mold is mirror-polished, and the inner peripheral surface that has become the mirror surface is subjected to a release treatment with a release agent such as fluororesin or silicone resin, and the formed endless belt is internally A metal tube that can be easily removed from the peripheral surface can be mentioned.

  Examples of the process for removing the solvent from the film-shaped molded body formed on the inner peripheral surface of the mold include a solvent removal process including the following primary solvent removal process and secondary solvent removal process. In the primary solvent removal step, the solvent is obtained by passing hot air of 40 to 150 ° C. into the mold for 5 to 60 minutes while the mold is rotated from the film-shaped molded body that is centrifugally formed by rotating the mold. Is removed. In the secondary solvent removal step following the primary solvent removal step, the film-shaped molded body is taken out of the mold together with the mold, and the taken-out film-shaped molded body is heated to 110 to 350 ° C. in a heating furnace, for example, a superheated steam furnace. Heat for ~ 120 minutes, thereby removing the solvent in the film-like molded body.

  After uniformly forming the film-shaped molded body, the film-shaped molded body is taken out together with the mold, or after removing the solvent from the film-shaped molded body, the film-shaped molded body is taken out and allowed to cool. In addition, when the film-shaped molded body is allowed to cool together with the mold, the film-shaped molded body made of the resin composition can be removed due to the difference in thermal expansion coefficient between the mold and the film-shaped molded body. The belt base layer 2 is manufactured by removing both end portions of the demolded cylindrical film-shaped molded body and cutting each predetermined width.

  When a polyamideimide resin is selected as the resin contained in the resin composition, in addition to the above-described centrifugal molding, a polyamic acid obtained by partially polymerizing a tricarboxylic acid anhydride and a diisocyanate compound, which are raw materials of the polyamideimide resin, is used. Is applied to the inner and outer peripheral surfaces of the mold by a dipping method, a centrifugal method, a coating method, etc., or is developed into a cylindrical shape by an appropriate method such as filling the casting mold with the polyamic acid solution. The developed layer is dried to form a belt shape, and the molded product is heat treated to convert the polyamic acid to an imide and recover from the mold (Japanese Patent Laid-Open No. 61-95361, The belt base layer 2 can also be manufactured by Japanese Patent Laid-Open Nos. 64-22514 and 3-180309.

  Before the elastic layer 3 is formed, the surface of the belt base layer 2 may be surface-treated in that the adhesion between the belt base layer 2 and the elastic layer 3 can be secured. A primer layer and / or an adhesive layer may be provided.

  The surface treatment of the belt base layer 2 is not particularly limited, and examples thereof include a surface treatment by ultraviolet irradiation and a surface treatment by infrared irradiation. These surface treatment conditions can be arbitrarily selected.

  The primer layer and the adhesive layer are formed by applying an adhesive or a primer to the surface of the belt base layer 2 by a spray method, a roll coating method, a dipping method, or the like. The primer is not particularly limited, and examples thereof include a silane coupling primer. Further, the adhesive is not particularly limited, but for example, an adhesive having an amino group and / or a hydroxyl group is suitable. Examples thereof include, for example, alkyd resins, phenol-modified / silicone-modified alkyd resin modified products, oil-free alkyd resins, acrylic resins, silicone resins, epoxy resins, fluororesins, phenol resins, polyamide resins, urethane resins, and mixtures thereof. Is mentioned. Moreover, an isocyanate compound, a melamine compound, an epoxy compound, a peroxide, a phenol compound, a hydrogensiloxane compound, etc. are used as a crosslinking agent for curing these resins.

  Next, if desired, the elastic layer 3 is formed on the outer peripheral surface of the belt base layer 2 that is surface-treated and / or on which the primer layer and / or the adhesive layer is formed. For example, the elastic layer 3 can be formed by applying the rubber composition capable of forming the elastic layer 3 to the outer peripheral surface of the belt base layer 2 and curing the rubber composition. Specifically, the cylindrical inner mold having an outer diameter substantially the same as the inner diameter of the belt base layer 2 and the endless belt 1 taking into account the linear shrinkage of the elastic layer 3 from the outer peripheral diameter of the cylindrical inner mold. Before or after assembling the belt base layer 2 on the outer peripheral surface of the inner mold and assembling the inner mold and the outer mold using a cylindrical outer mold having an inner diameter that is larger by the total thickness, A method of laminating the rubber composition on the outer peripheral surface of the belt base layer 2 and curing the rubber composition may be mentioned. The outer mold has a gas vent for allowing gas generated from the foaming agent to escape from the mold.

  The method of laminating the rubber composition on the outer peripheral surface of the belt base layer 2 is not particularly limited. For example, (1) a sheet-shaped rubber composition dispensed to a desired thickness by an extruder such as a mixing roll. A method in which the raw material is cut into a desired length and wound around the outer peripheral surface of the belt base layer 2, and (2) the raw material of the cylindrical rubber composition extruded seamlessly by an extrusion molding method or the like is converted into the belt base layer. (3) After assembling the inner mold and the outer mold in which the belt base layer 2 is inserted, from the rubber composition inlet provided in the outer mold, the belt base layer 2 and Examples include a method of injecting a rubber composition into a gap formed between the outer mold and laminating or charging the rubber composition on the outer peripheral surface of the belt base layer 2. Among these methods, the methods (2) and (3) are preferable in that no seam is formed in the elastic layer and the uniform elastic layer 3 can be formed over the entire circumference.

  Next, the rubber composition laminated on the outer peripheral surface of the belt base layer 2 is cured. Curing conditions may be selected from known conditions depending on the rubber composition, the foaming agent, etc. For example, when the addition reaction type foamed silicone rubber composition is selected as the rubber composition, the heating temperature is usually The conditions are selected from 100 to 500 ° C., preferably 200 to 400 ° C., and the heating time is several minutes to 1 hour, preferably 5 to 30 minutes. If desired, the rubber composition may be subjected to secondary heating.

  In this way, when the elastic layer 3 is formed on the outer peripheral surface of the belt base layer 2 by the addition reaction type foamed silicone rubber composition using the inner mold and the outer mold, the elastic layer 3 has the structure shown in FIG. As shown, a skin layer 4A having a surface to which the surface state of the inner peripheral surface of the outer mold is transferred is formed integrally with the elastic layer 3A on the outer surface side. The thickness of the skin layer 4A can be adjusted, for example, by adjusting the gap (clearance) between the inner mold and the outer mold.

  In order to form the elastic layer 3 and the skin layer 4 separately, for example, the rubber composition, for example, a rubber composition other than the addition reaction type foamed silicone rubber composition is cured in accordance with the above method, and elastic. The layer 3B is formed, or the skin layer 4 formed integrally with the elastic layer 3A is cut by polishing or the like according to the above method to form the elastic layer 3B, and then the rubber composition is formed on the outer peripheral surface of the elastic layer 3B. May be cured according to the above method.

  Next, if desired, the material is applied to the surface of the skin layer 4 by spraying, roll coating, dipping, or the like, and the applied material is baked or dried to form the coating layer 5.

  In the manufacturing method of the endless belt 1, the elastic layer 3 and the like are formed on the outer peripheral surface of the belt base 2, but after forming the elastic layer 3 and the like on the inner peripheral surface of the belt base 2, the front and back of the belt base 2 are covered. The endless belt 1 can also be manufactured by reversing.

  The endless belt 1 has a single elastic layer 3, but in the present invention, the elastic layer may have two or more layers.

  The endless belt 1 does not include the meander-preventing member of the endless belt 1, but in the present invention, in the vicinity of at least one end of the belt base, a hook shape, a rail shape, and the like extending in the circumferential direction of the belt base You may provide the meander prevention member which comprised elongate shapes, such as strip | belt shape.

  Next, an example of an image forming apparatus provided with the endless belt 1 according to the present invention (hereinafter sometimes referred to as an image forming apparatus according to the present invention) will be described with reference to FIG. Conditions for attaching the endless belt 1 are not particularly limited, but in the image forming apparatus, the endless belt 1 is stretched around a support roller with a tension of, for example, 100 to 3,000 gf.

  As shown in FIG. 4, the image forming apparatus 10 according to the present invention includes a rotatable image carrier 11 on which an electrostatic latent image is formed, for example, a photosensitive member, and abuts or presses against the image carrier 11 or A charging unit 12 that charges the image carrier 11, for example, a charging roller, and an exposure unit 13 that is provided above the image carrier 11 and forms an electrostatic latent image on the image carrier 11. A developing unit 20 which is provided in contact with or pressure contact with the image carrier 11 or at a predetermined interval, supplies the developer 22 with a constant layer thickness to the image carrier 11 and develops the electrostatic latent image; The transfer unit 14 is provided so as to be pressed against the image carrier 11 and transfers the developed electrostatic latent image from the image carrier 11 onto the recording medium 16 such as a recording paper. Provided downstream in the direction and transferred to the recording medium 16. Fixing means 15 for fixing the image agent 22 (electrostatic latent image), for example, a fixing device, developer 22 not transferred to the recording medium 16 and remaining on the image carrier 11 and / or dust adhering to the image carrier 11 and the like. And a cleaning means 17 to be removed.

  The fixing means 15 has a fixing roller 15a and an endless belt support disposed in the vicinity of the fixing roller 15a in a casing 18 having an opening 19 through which the recording medium 16 passes, as shown in FIG. A roller 15c, an endless belt 1A wound around the fixing roller 15a and the endless belt support roller 15c, and a pressure roller 15b disposed opposite to the fixing roller 15a. The roller 15c is added to the fixing roller 15a via the endless belt 1A. This is a pressure heat fixing device that is rotatably supported so that the pressure roller 15b is in contact with or in pressure contact with each other. Each of the fixing roller 15a, the pressure roller 15b, and the endless belt support roller 15c has a built-in heating body (not shown). The pressure roller 15b applies the endless belt 1A to a biasing means (not shown) such as a spring. Via the fixing roller 15a. The endless belt 1A is stretched between the fixing roller 15a and the endless belt support roller 15c with, for example, a tension of 100 to 3,000 gf.

  As shown in FIG. 4, the developing means 20 includes a casing 21 that stores the developer 22, and an image of the developer 22 that is disposed in the vicinity of the image carrier 11 and that is stored in the casing 21. A developer carrier 24 supplied to the carrier 11, such as a developing roller, is provided in contact with or pressed against the developer carrier 24, and a rotatable developer supply means for supplying the developer 22 to the developer carrier 24. 23, for example, a developing roller, and a developer amount adjusting means 25 made of an elastic member for adjusting the thickness of the developer 22 so that the developer 22 is held at a constant thickness on the surface of the developer carrier 24, for example, a blade Comprising. The developer 22 may be a dry developer or a wet developer as long as it is a one-component developer or a two-component developer that can be charged by friction and can be fixed to the recording medium 16. Further, it may be a nonmagnetic developer or a magnetic developer. As the one-component developer or the two-component developer, a known developer can be used without any particular limitation.

  According to the image forming apparatus 10, an image is formed on the recording body 16 as follows. That is, the exposure unit 13 forms an electrostatic latent image on the surface of the rotating image carrier 11. When the developer 22 is supplied from the developing means 20 to the image carrier 11 by the developer carrier 24, the developer 22 is electrostatically attached to the electrostatic latent image formed on the surface of the image carrier 11 and developed. Is formed. When the recording medium 16 conveyed by the conveying means (not shown) is sandwiched between the transfer means 14 and the image carrier 11 and passes between them, the development formed on the surface of the image carrier 11 is recorded. It is transferred to the surface of the body 16. The recording medium 16 to which the development has been transferred is transported by the transport unit and reaches the fixing unit 15. In the fixing unit 15, the conveyed recording medium 16 passes between the endless belt 1A and the pressure roller 15b. As a result, the developer 22 that forms the development existing on the surface of the recording medium 16 is heated and melted simultaneously with the pressurization, and is fixed to the recording medium 16. Thus, an image by the developer is formed on the surface of the recording medium 16.

  In the image forming apparatus 10, since the endless belt 1A is used as the fixing belt, the dimensions of the fixing roller 15a, the endless belt support roller 15c, the endless belt 1A, the distance between the fixing roller 15a and the endless belt support roller 15c, and the like. Without adjusting the endless belt 1A and the pressure roller 15b without adjusting the tension of the endless belt 1A stretched between the fixing roller 15a and the endless belt support roller 15c. The contact area and the contact pressure can be adjusted as desired. Even if the image forming apparatus 10 operates for a long period of time, the endless belt 1A can effectively absorb changes in the contact area, the contact pressure, and the like between the endless belt 1A and the pressure roller 15b. Further, the endless belt 1A can increase the contact area with the pressure roller 15b, that is, increase the contact area with the recording paper 16, so that the developer 22 is recorded as desired. It can be fixed on the paper 16. Therefore, according to the image forming apparatus 10, a high-quality image can be formed over a long period of time regardless of the mounting condition and the image forming condition of the endless belt 1A.

  Next, another example of the image forming apparatus according to the present invention will be described with reference to FIG. As shown in FIG. 5, the image forming apparatus 30 has a plurality of image carriers 11B, 11C, 11M, and 11Y that are mounted on the developing units B, C, M, and Y of the respective colors arranged in series on the endless belt 1B. Therefore, the developing units B, C, M and Y are arranged in series on the endless belt 1B. In this image forming apparatus, an endless belt 1B is used as a transfer conveyance belt. The endless belt 1B is stretched between two support rollers 33 with, for example, a tension of 100 to 3,000 gf. Each of the developing units B, C, M, and Y is configured similarly to the developing device in the image forming apparatus 10 shown in FIG. In FIG. 5, the developer supply means 23 is not shown.

  The developers 22B, 22C, 22M and 22Y used in the image forming apparatus 30 can be dry-developed as long as they are one-component developers or two-component developers that can be charged by friction and can be fixed to the recording medium 16. It may be a developer or a wet developer, and may be a non-magnetic developer or a magnetic developer. The developing units B, C, M, and Y are respectively a one-component or two-component black developer 22B, cyan developer 22C, magenta developer 22M, and yellow developer in the casings 21B, 21C, 21M, and 21Y. The agent 22Y is stored.

  As shown in FIG. 5, the image carrier 11 and the transfer unit 14 in the developing units B, C, M, and Y are in contact with each other via an endless belt 1 </ b> B stretched between two support rollers 33. It is in pressure contact. The endless belt 1B is stretched around the two support rollers 33 with, for example, a tension of 100 to 3,000 gf. Then, the recording body 16 is conveyed by the endless belt 1 </ b> B so as to pass through the contact portion between the image carrier 11 and the transfer unit 14.

  As shown in FIG. 5, at the bottom of the image forming apparatus 30, a cassette 31 formed by stacking and storing a plurality of recording bodies is installed as the recording body 16, and the recording body in the cassette 31 is a paper feed roller. Etc., one by one, and conveyed onto the endless belt 1B.

  As shown in FIG. 5, a fixing unit 15 that fixes the developer 22 (electrostatic latent image) transferred to the recording body 16 is disposed downstream in the conveyance direction of the recording body 16 in the image forming apparatus 30. . The fixing unit 15 is basically configured in the same manner as the fixing unit 15 in the image forming apparatus 10 shown in FIG. 4 except that it does not include a transfer belt.

  The image forming apparatus 30 forms a color image on the recording body 16 as follows. First, in the developing unit B, similarly to the image forming apparatus 10, the electrostatic latent image developed in black is visualized on the recording medium 16. Next, in the same manner as the developing unit B, the electrostatic latent images are visualized as black images by the developing units C, M, and Y, and the cyan image and magenta are respectively transferred to the recording medium 16 conveyed by the endless belt 1B. The image and the yellow image are superimposed, and the color image is visualized. Next, the recording body 16 in which the color image is visualized is conveyed to the fixing unit 15, and the color image is fixed on the recording body 16 as a permanent image by the fixing unit 15. In this way, a color image can be formed on the recording medium 16.

  In this image forming apparatus 30, since the endless belt 1B is used as the transfer conveyance belt, the dimensions and distances of the image carrier 11, the transfer unit 14, the endless belt 1B, and the support roller 33 need not be adjusted very strictly. In addition, the contact area and contact pressure between the endless belt 1B and the transfer means 14 are adjusted as desired without strictly adjusting the tension of the endless belt 1B stretched around the support roller 33. can do. Even if the image forming apparatus 10 operates for a long period of time, the endless belt 1B can effectively absorb changes in the contact area, contact pressure, and the like between the endless belt 1B and the transfer unit 14. Further, the endless belt 1B can increase the contact area with the transfer unit 14, that is, can increase the contact area with the recording paper 16, and is excellent in non-adhesiveness to the image carrier 11. Therefore, the recording body 16 can be transported to each of the developing units B, C, M, and Y without causing misalignment during transportation, and the recording body 16 can be transported to the fixing unit 15 without causing paper jam. can do. Therefore, according to the image forming apparatus 30, a high-quality image can be formed over a long period of time regardless of the mounting condition and the image forming condition of the endless belt 1B.

  In the image forming apparatuses 10 and 30, the endless belt 1 is used as a fixing belt and a transfer conveyance belt. In the present invention, the endless belt 1 is used as a transfer belt, an intermediate transfer belt, a conveyance belt, a development belt, or the like. It may be mounted on a forming device. The transfer belt (sometimes referred to as a photosensitive belt) plays the same role as the image carrier 11. On the intermediate transfer belt, the developer image visualized by the image carrier 11 is temporarily transferred (primary transfer), then transferred to the recording body 16 (secondary transfer), and the image is transferred to the recording body 16. When used, it is used as a primary transfer member. The conveyance belt conveys the recording medium 16. The developing belt plays the same role as the developer supply means 23.

  As described above, when the endless belt 1 is attached to the image forming apparatuses 10 and 30 as a transfer belt, an intermediate transfer belt, and a developing belt, the endless belt 1 changes in the contact area with the contacted body, the contact pressure, and the like. Can be effectively absorbed over a long period of time, so that a high-quality image can be formed over a long period of time, and the contact area with the recording body 16 is increased, so that the recording body 16 can be conveyed as desired. can do. In addition, when the endless belt 1B is attached to the image forming apparatuses 10 and 30, the developer can be supplied or conveyed as desired because the toner peelability and the non-adhesiveness to the contacted body are excellent. High quality images can be formed.

  The image forming apparatuses 10 and 30 are image forming apparatuses such as copiers, facsimiles, and printers.

  The image forming apparatuses 10 and 30 are electrophotographic image forming apparatuses. However, in the present invention, the image forming apparatuses 10 and 30 are not limited to the electrophotographic system, and for example, electrostatic image forming. It may be a device. Further, the image forming apparatus provided with the endless belt 1 includes a monochrome image forming apparatus 10 having a single developing unit and a plurality of image carriers having developing units of respective colors in series on a transfer conveyance belt. The image forming apparatus 30 is not limited to the tandem color image forming apparatus 30. For example, a four-cycle color image forming apparatus that sequentially repeats primary transfer of a developer image carried on an image carrier onto an endless belt may be used.

(Example 1)
In a reaction vessel, an equivalent amount of trimellitic anhydride and 4,4'-diaminodiphenylmethane are dissolved in N, N-dimethylacetamide and heated to obtain a solid concentration (substantially fully ring-closed polyamideimide). A 28% by weight aromatic polyamideimide solution was obtained. N, N-dimethylacetamide was further added to this solution to prepare a polyamideimide solution having a solid content concentration of 15% by mass and a solid content specific gravity of 1.2. To this polyamide-imide solution, an oxidized carbon black (trade name “Printex 150T”, manufactured by Degussa, pH 5.8, volatile content 10.0%) as a conductivity-imparting agent is added to the polyamide-imide solution and the conductivity-imparting agent. It mix | blended so that it might become 15 mass% with respect to a total of 100 mass%, and it mixed and disperse | distributed with the pot mill for 24 hours, and obtained the resin composition mixed solution. The mold used for molding has an inner diameter of 226 mm, an outer diameter of 246 mm, and a length of 400 mm, and the inner surface of the mold is mirror-polished by polishing. Ring-shaped lids (inner diameter: 170 mm, outer diameter: 250 mm) are fitted into the openings at both ends of the mold to close the mold, and the prepared mixed solution is placed on the inner periphery of the mold rotating at a speed of 1000 rpm. 190 g was injected. Next, the mold was rotated at the same speed to level the solution, and the temperature around the mold was maintained at 80 ° C. by a hot air dryer, and this state was maintained for 30 minutes. Thereafter, the rotation of the mold was stopped, and the entire mold was put into an oven at 180 ° C. for 45 minutes. Next, the mold was removed from the oven, the mold was left to cool at room temperature, and the endless belt molded body was removed from the mold by utilizing the difference in thermal expansion between the mold and the endless belt base material. Both end portions of the endless belt molded body were cut to a width of 240 mm, and a belt base layer 2 having an outer diameter of 226 mm and a thickness of about 100 μm was produced.

The surface of the belt base layer 2 is irradiated with ultraviolet rays having a dominant wavelength of 253.7 nm and 184.9 nm and an integrated light amount of 1.2 to 76 J / cm ² by a low-pressure mercury lamp, and then a primer “No. 101A / B” (Shin-Etsu Chemical Co., Ltd. product name) was applied. The primer-treated belt base layer 2 was fired at 180 ° C. for 30 minutes using a gear oven, and then cooled at room temperature for 30 minutes or more to form a primer layer.

  On the other hand, a silicone rubber composition “KE-904FU” (manufactured by Shin-Etsu Chemical Co., Ltd .: trade name) containing a vinyl group-containing silicone raw rubber and a silica-based filler, and an addition reaction crosslinking agent “C-153A” ( Shin-Etsu Chemical Co., Ltd .: trade name) 2.0 parts by mass, foaming agent “KEP-13” (Shin-Etsu Chemical Co., Ltd .: trade name) 3.0 parts by mass, and an appropriate amount of platinum catalyst as an addition reaction catalyst And a suitable amount of a reaction control agent and an appropriate amount of “C-3” (manufactured by Shin-Etsu Chemical Co., Ltd .: trade name) as an organic peroxide cross-linking agent without using a conductivity-imparting agent. The addition reaction type foamed silicone rubber composition was prepared by sufficiently kneading.

  Next, the belt base layer 2 on which the primer layer is formed is inserted into the inner mold (outer diameter 226.5 mm), the inner mold, the outer mold (inner diameter 229.5 mm), and the two lid members are assembled, and the outer mold is assembled. 8 g of the prepared addition reaction type foamed silicone rubber composition was charged into a gap formed between the belt base layer 2 and the outer mold from the rubber composition inlet of the mold. Then, using an infrared heating furnace (IR furnace), each mold was heated at 250 ° C. for 10 minutes to foam-crosslink the addition reaction type foamed silicone rubber composition. Thereafter, the addition reaction type foamed silicone rubber composition after foaming and crosslinking is secondarily heated at 200 ° C. for 7 hours using a gear oven and left at room temperature for 1 hour to complete the entire outer circumference of the belt base layer 2. An endless belt I was prepared by integrally forming a foam elastic layer 3A having a thickness of 2.9 mm on the surface and a skin layer 4A having a thickness of 100 μm on the entire outer peripheral surface of the foam elastic layer 3A.

The average cell diameter of the cells 7 formed in the elastic layer 3A, the ratio of the maximum cell diameter r _max to the minimum cell diameter r _min (r _max / r _min ), the standard deviation σ of the cell diameter, and the distance between the cells are measured by the above methods. As a result, the average cell diameter of the cell 7 is 300 μm, r _max / r _min is 1.4, the standard deviation σ of the cell diameter of the cell 7 is 0.05, and the inter-cell distance is 0.3 mm. there were. Also, when the Asker C hardness of the skin layer 4A and the density when the foam elastic layer 3A and the skin layer 4A are one layer were measured by the above method, the Asker C hardness was 35 and the density was 0.00. It was 35 g / cm ³ .

(Example 2)
An endless belt II was produced in the same manner as in Example 1 except that the amount of the foaming agent “KEP-13” in the addition reaction type foamed silicone rubber composition was changed to 2.0 mass%. In the endless belt II, the average cell diameter of the cell 7 is 400 μm, r _max / r _min is 1.45, the standard deviation σ of the cell diameter of the cell 7 is 0.07, and the inter-cell distance is 0. It was 4 mm. The Asker C hardness was 55, and the density was 0.3 g / cm ³ .
(Example 3)
An endless belt III was produced in the same manner as in Example 1, except that the amount of the foaming agent “KEP-13” in the addition reaction type foamed silicone rubber composition was changed to 4.0% by mass. In the endless belt III, the average cell diameter of the cell 7 is 500 μm, r _max / r _min is 1.5, the standard deviation σ of the cell diameter of the cell 7 is 0.1, and the inter-cell distance is 0. It was 5 mm. The Asker C hardness was 25, and the density was 0.25 g / cm ³ .
Example 4
After the foam elastic layer 3A and the skin layer 4A were integrally formed in the same manner as in Example 1, a urethane paint (trade name “Takelac E-553”, manufactured by Mitsui Chemicals Polyurethane Co., Ltd.) was formed on the outer peripheral surface of the skin layer 4A. ) Was applied. Next, using a gear oven, a baking treatment was performed at a temperature of 200 ° C. for 30 minutes to produce an endless belt IV in which the coat layer 5 was formed on the entire outer peripheral surface of the skin layer 4. In the endless belt IV, the average cell diameter of the cell 7 is 300 μm, r _max / r _min is 1.4, the standard deviation σ of the cell diameter of the cell 7 is 0.05, and the inter-cell distance is 0. It was 3 mm. The Asker C hardness was 35, and the density was 0.35 g / cm ³ . Furthermore, the Asker C hardness of the coat layer 5 was 40.

  In addition, the endless belts I to IV were separately manufactured, the foam elastic layer 3A was peeled from the belt base layer 2, and the Asker C hardness of the foam elastic layer 3A was measured by the above method. As a result, each of the foam elastic layers 3A of the endless belts I to IV had an Asker C hardness of 10 to 50.

(Comparative Example 1)
An endless belt V was produced in the same manner as in Example 1 except that the foam elastic layer 3A and the skin layer 4A were not formed.
(Comparative Example 2)
An endless belt VI having an elastic layer having no cells and a skin layer 4A was produced in the same manner as in Example 1 except that the foaming agent “KEP-13” in the addition reaction type foamed silicone rubber composition was not blended. . In endless belt VI, Asker C hardness was 80, and density was 1.3 g / cm ³ .

  The endless belts I to VI thus produced are mounted as a transfer conveyance belt in the image forming apparatus trade name “DocuPrint C830” (manufactured by Fuji Xerox Co., Ltd.) shown in FIG. 5, and the mounted state and mounting workability are evaluated. did.

  In the mounted state, when the endless belts I to VI are stretched around the support roller 33, the contact area and the contact pressure with respect to the image carriers 11B to 11Y and the transfer units 14B to 14Y and the tension applied to the endless belts I to VI are reduced. Evaluation was made based on whether or not it was within the desired range. Further, the mounting workability was evaluated based on the work efficiency and the mounting state when a plurality of the image forming apparatuses were prepared and endless belts were mounted on the respective image forming apparatuses in the same manner.

  As a result, in the endless belts I to IV and VI, in any of the image forming apparatuses, the contact area, the contact pressure, and the tension are within desired ranges, and the mounting workability is excellent. In the plurality of image forming apparatuses, the endless belt V has at least one of the contact area, the contact pressure, and the tension within a desired range, and has poor mounting workability.

  Also, using each image forming apparatus equipped with the endless belts I to VI, after printing 10,000 sheets in an environment of a temperature of 22 ° C. and a relative humidity of 60%, the mounting state and the mounting workability are similarly evaluated. did. As a result, in the endless belts I to IV, in any of the image forming apparatuses, the contact area, the contact pressure, and the tension are within the desired ranges, whereas the endless belts V and VI are In a plurality of image forming apparatuses, at least one of the contact area, the contact pressure, and the tension that were within the desired range was not maintained within the desired range after printing 10,000 sheets.

  Further, each image forming apparatus equipped with the endless belts I to VI was changed from an environment having a temperature of 22 ° C. and a relative humidity of 60% to an environment having a temperature of 35 ° C. and a relative humidity of 95%, and 10,000 sheets were printed. Thereafter, the mounting state and the mounting workability were evaluated in the same manner. As a result, in the endless belts I to IV, in any of the image forming apparatuses, the contact area, the contact pressure, and the tension are within the desired ranges, whereas the endless belts V and VI are In a plurality of image forming apparatuses, at least one of the contact area, the contact pressure, and the tension that were within the desired range was not maintained within the desired range after the image forming conditions were changed.

  The endless belts I to VI are mounted as a conveyor belt, a developing belt, and a fixing belt in an image forming apparatus, and even when 10,000 sheets are printed, the developer is conveyed by a desired conveyance amount and recorded as desired. The body could be transported, resulting in the formation of high quality images.

  The addition reaction type foamed silicone rubber composition has 20% by mass of a conductivity-imparting agent (carbon black, trade name “IGS-60”, manufactured by Nippon Kasei Techno Carbon Co., Ltd. with respect to the total mass of 100% by mass. ) To prepare an endless belt having the foam elastic layer 3A and the skin layer 4A formed thereon, and the mounting state, mounting workability, image quality, and the like were evaluated in the same manner. As a result, basically the same results as in Examples 1 to 4 and Comparative Examples 1 and 2 were obtained.

FIG. 1 is a schematic perspective view of an endless belt as an example of the present invention. FIG. 2 is a schematic cross-sectional view of an endless belt as another example of the present invention. FIG. 3 is a schematic cross-sectional view of an endless belt which is still another example of the present invention. FIG. 4 is a schematic view showing an example of an image forming apparatus according to the present invention. FIG. 5 is a schematic view showing another example of the image forming apparatus according to the present invention.

Explanation of symbols

1A, 1B Endless belt 2 Belt base layer 3A, 3B Foam elastic layer (elastic layer)
4A, 4B Skin layer 5 Coat layer 7 Cell 10, 30 Image forming apparatus 11, 11B, 11C, 11M, 11Y Image carrier 12, 12B, 12C, 12M, 12Y Charging means 13, 13B, 13C, 13M, 13Y Exposure means 14, 14B, 14C, 14M, 14Y Transfer means 15 Fixing means 15a Fixing roller 15b Pressure roller 15c Endless belt support roller 16 Recording member 17, 17B, 17C, 17M, 17Y Cleaning means 18, 21, 21B, 21C, 21M, 21Y housing 19 opening 20, 20B, 20C, 20M, 20Y developing means 22, 22B, 22C, 22M, 22Y developer 23 developer supplying means 24, 24B, 24C, 24M, 24Y developer carrier 25, 25B, 25C , 25M, 25Y Developer regulating member 31 Cassette 33 Support rollers B, C M, Y developing unit

Claims (3)

  An endless belt comprising a belt base layer, a foam elastic layer formed on the outer peripheral surface of the belt base layer, and a skin layer formed on the outer peripheral surface of the foam elastic layer.   The endless belt according to claim 1, further comprising a coat layer on an outer peripheral surface of the skin layer. An image forming apparatus comprising the endless belt according to claim 1.

Images