JP2010085518A - Endless belt and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an endless belt which excels in releasing properties of developer and maintains an initial pressure contact state with a cleaning blade over a long term, and to provide an image forming apparatus which forms a high-quality image. <P>SOLUTION: The endless belt 1 includes an endless belt substrate 2, and an urethane elastic layer 3 formed on the endless belt substrate 2, wherein the elastic layer 3 contains silica. The image forming apparatus includes the endless belt 1 and the cleaning blade brought into pressure contact with an outer surface of the endless belt 1. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an endless belt and an image forming apparatus, and more specifically, an endless belt that is excellent in developer releasability and that can maintain an initial pressure contact state with a cleaning blade for a long period of time, and a high The present invention relates to an image forming apparatus capable of forming a quality image.

  Various image forming apparatuses using an electrophotographic system are employed in printers such as laser printers and video printers, copiers, facsimiles, and multi-function machines thereof. An image forming apparatus using an electrophotographic system is, for example, a direct transfer system that directly transfers a developer image developed on an image carrier to a recording body according to the function of an endless belt, and a developer image that is once endless. There is an intermediate transfer method in which the image is transferred to a belt and transferred from an endless belt to a recording medium.

  In the direct transfer method, an electrostatic latent image formed on an image carrier such as a photosensitive drum is developed with a developer supplied from a developer carrier provided in a developing unit, and the developed developer image is By applying a voltage to the transfer unit, the image is electrostatically attracted to an endless belt (also referred to as a transfer conveyance belt), transferred to a recording medium conveyed between the image carrier and the transfer unit, and then transferred. In this method, the recording medium on which the developer image has been transferred is pressed or heat-pressed by a pressure roller and a fixing roller to fix the developer image on the recording medium as an image or a character.

  In the intermediate transfer system, for example, an electrostatic latent image formed on an image carrier is developed with a developer, and the developed developer image is contacted or pressed against the image carrier (also referred to as an intermediate transfer belt). ) (Primary transfer), the developer image transferred to the endless belt is transferred to the recording body (secondary transfer), and the recording body onto which the developer image has been transferred is pressure-bonded or pressed by a pressure roller and a fixing roller. This is a system in which the developer image transferred by thermocompression bonding is fixed as an image or text on the recording medium. Such an intermediate transfer type image forming apparatus is widely used because it has a good developer transfer property, and it is relatively easy to realize colorization and high definition of an image and high image forming speed. ing.

  Endless belts, for example, intermediate transfer belts, mounted on these image forming apparatuses carry the developer and supply it to the recording medium, and therefore need to have excellent developer transfer and releasability. When the releasability of the developer on the endless belt is inferior, the developer carried on the endless belt cannot be supplied to the recording body as desired, and as a result, the density of the formed image is insufficient, White spots are generated in the formed image where the developer is not transferred. In particular, in order to form a desired image on an endless belt attached to a recent image forming apparatus in which high-definition images, high-speed printing, and / or small size and light weight are achieved. There is a demand for more excellent developer releasability.

  In some cases, the endless belt has a multilayer structure for the purpose of improving the transferability or releasability of the developer and improving the durability. For example, Patent Document 1 discloses that “a base layer made of an elastomer material and a surface layer covering the surface of the base layer are provided, and this surface layer has a non-fluorine polymer and a contact angle with water of 100 degrees or more. An elastic member for office equipment containing a fluororesin ”. Further, Patent Document 2 discloses that “a photosensitive member, a plurality of developing devices that supply toner to the photosensitive member, an intermediate transfer member that transfers and holds toner on the photosensitive member, and a transfer from the intermediate transfer member to a printing medium”. A color image forming apparatus having a transfer unit, wherein the intermediate transfer member is a cylindrical belt and has a three-layer structure including a belt base layer, a binder layer, and a fine particle layer. Are listed.

  By the way, an image forming apparatus including such an endless belt includes a cleaning blade that presses against an outer surface of the endless belt for scraping off the developer remaining on the surface of the endless belt.

  The cleaning blade is usually arranged on the downstream side in the running direction of the endless belt so that the end or edge of the cleaning blade comes into contact with the outer surface of the endless belt at a predetermined angle and a predetermined pressing force. . As described above, the cleaning blade is pressed near the end or the edge of the endless belt so that the cleaning blade turns back in the traveling direction of the endless belt due to friction with the endless belt, and functions sufficiently as a cleaning blade. It may disappear. In particular, in an image forming apparatus in which the printing speed, that is, the traveling speed of the endless belt is increased, an excessive load is applied to the end or edge of the cleaning blade that presses the endless belt when the endless belt travels. It becomes easier to turn around.

JP 2001-42663 A JP 2004-354716 A

  The present invention provides an endless belt having excellent developer releasability and capable of maintaining the initial pressure contact state with a cleaning blade for a long period of time, and forming a high-quality image. It is an object of the present invention to provide an image forming apparatus that can be used.

As means for solving the problems,
Claim 1 is an endless belt comprising an endless belt base and a urethane elastic layer formed on the endless belt base, the urethane elastic layer containing silica.
Claim 2 is the endless belt according to claim 1, wherein the urethane elastic layer contains a fluororesin.
Claim 3 is the endless belt according to claim 1 or 2, wherein the urethane elastic layer has a static friction coefficient in the range of 0.7 to 1.7.
A fourth aspect of the present invention is an image forming apparatus comprising: the endless belt according to any one of the first to third aspects; and a cleaning blade that presses against an outer surface of the endless belt.

  In the endless belt according to the present invention, since the urethane elastic layer containing silica is formed on the endless belt substrate, the urethane elastic layer is excellent in the releasability of the developer and is placed on the pressure contacted cleaning blade. It is possible to prevent the cleaning blade from slipping back in the traveling direction of the endless belt by sliding. Therefore, according to the present invention, it is possible to provide an endless belt that is excellent in the releasability of the developer and can maintain the initial pressure contact state with the cleaning blade for a long period of time.

  In addition, since the image forming apparatus according to the present invention includes the endless belt according to the present invention, the endless belt is excellent in the releasability of the developer and slides on the cleaning blade, The initial pressure contact state can be maintained over a long period of time. Therefore, according to the present invention, an image forming apparatus capable of forming a high quality image can be provided.

  An endless belt which is an embodiment of an endless belt according to the present invention will be described with reference to the drawings. As shown in FIG. 1, the endless belt 1 includes an endless belt base 2 and a urethane elastic layer (hereinafter sometimes referred to as an elastic layer) 3 formed on the outer peripheral surface of the endless belt base 2. Prepare. That is, the endless belt according to the present invention has the elastic layer 3 containing silica as a surface layer.

  The endless belt 1 having a two-layer structure including the endless belt base 2 and the elastic layer 3 is set to have a desired width and inner peripheral diameter according to the use of the endless belt 1 or the like. For example, the endless belt 1 has a width of 200 to 350 mm and an inner peripheral diameter of 200 to 2,500 mm. Moreover, although the whole thickness of the endless belt 1 is not specifically limited, Usually, it is preferable that it is 0.03-1 mm, for example, it is more preferable that it is 0.05-0.2 mm, and 0.07-0. It is particularly preferably about 14 mm. When the thickness of the endless belt 1 is within the above range, mechanical strength and flexibility can be ensured, and the durability is excellent. The thickness of the endless belt 1 is measured in the same manner as the endless belt substrate 2.

The endless belt 1 preferably has a surface resistivity of 1 × 10 ⁹ to 1 × 10 ¹³ Ω / □, and has a surface resistivity of 1 × 10 ⁹ to 1 × 10 ¹² Ω / □. More preferably, it has a surface resistivity of 1 × 10 ⁹ to 1 × 10 ¹¹ Ω / □. When the surface resistivity is within the above range, a high-quality image can be formed when the endless belt 1 is used in an image forming apparatus. For the surface resistivity, a test piece corresponding to the endless belt 1 such as the endless belt 1 or a test piece cut out from the endless belt 1 or a test piece produced in the same manner as the endless belt 1 is prepared. The layer is measured in the same manner as the surface resistivity of the endless belt substrate 2 described later.

The endless belt 1 preferably has a volume resistivity of 1 × 10 ⁸ to 1 × 10 ¹² Ω · cm, and has a volume resistivity of 1 × 10 ⁸ to 1 × 10 ¹¹ Ω · cm. More preferably, it has a volume resistivity of 1 × 10 ⁸ to 1 × 10 ¹⁰ Ω · cm. When the volume resistivity is within the above range, a high-quality image can be formed when the endless belt 1 is used in an image forming apparatus. For the volume resistivity, a test piece corresponding to the endless belt 1 such as the endless belt 1 or a test piece cut out from the endless belt 1 or a test piece produced in the same manner as the endless belt 1 is prepared. The layer is measured in the same manner as the volume resistivity of the endless belt base 2 described later. The surface resistivity and volume resistivity of the endless belt 1 can be adjusted in the same manner as the elastic layer 3, for example.

  The endless belt 1 preferably has elasticity, for example, generally preferably has a JIS A hardness of 40 to 90, and preferably has a JIS A hardness of 50 to 80. More preferably, it has a JIS A hardness of 50 to 70. When the endless belt 1 has a JIS A hardness within the above range, a sufficient contact width between the endless belt 1 and a member with which the endless belt 1 contacts when the endless belt 1 is attached to the image forming apparatus. Can be secured. The JIS A hardness of the endless belt 1 is measured in the same manner as the JIS A hardness of the elastic layer 3.

  As shown in FIG. 1, the endless belt base 2 is formed by curing a resin composition described later, and has a single layer structure. The endless belt base 2 has a desired width and inner peripheral diameter depending on the use of the endless belt 1, that is, the position (component) disposed in the image forming apparatus, the interval between a plurality of stretched rollers, and the like. Is set. Although the thickness of the endless belt base | substrate 2 is not specifically limited, Usually, it is preferable that it is 50-200 micrometers, for example, it is more preferable that it is 60-170 micrometers, and it is especially preferable that it is 70-160 micrometers. When the thickness of the endless belt substrate 2 is within the above range, the mechanical strength and flexibility when the endless belt 1 is obtained can be secured, and the durability of the endless belt 1 is excellent. The thickness of the endless belt base 2 can be measured by a contact-type film thickness meter or a non-contact-type film thickness meter, for example, an overcurrent film thickness meter (trade name “CTR-1500E”, Sanko Electronics Co., Ltd.). Can be used.

The endless belt substrate 2 preferably has a surface resistivity of 1 × 10 ⁹ to 1 × 10 ¹³ Ω / □, and has a surface resistivity of 1 × 10 ⁹ to 1 × 10 ¹² Ω / □. More preferably, it has a surface resistivity of 1 × 10 ⁹ to 1 × 10 ¹¹ Ω / □. When the surface resistivity is within the above range, a high-quality image can be formed when the endless belt 1 including the endless belt base 2 is used in an image forming apparatus. The surface resistivity of the endless belt base 2 is a test piece corresponding to the endless belt base 2 or a test piece cut out from the endless belt base 2 or a test piece produced in the same manner as the endless belt base 2. Was prepared in accordance with JIS K6911 using a circular electrode (eg, Mitsubishi Chemical Corporation, trade name: Hiresta-UP, probe used: URS probe) under conditions of a temperature of 23 ° C. and a relative humidity of 50%. The value when the surface resistivity of the test piece is measured can be obtained by arithmetic averaging.

The endless belt base 2 preferably has a volume resistivity of 1 × 10 ⁸ to 1 × 10 ¹² Ω · cm, and has a volume resistivity of 1 × 10 ⁸ to 1 × 10 ¹¹ Ω · cm. More preferably, it has a volume resistivity of 1 × 10 ⁸ to 1 × 10 ¹⁰ Ω · cm. When the volume resistivity is within the above range, a high-quality image can be formed when the endless belt 1 including the endless belt base 2 is used in an image forming apparatus. The volume resistivity of the endless belt base 2 is a test piece corresponding to the endless belt base 2 or the endless belt base 2 such as a test piece cut out from the endless belt base 2 or a test piece produced in the same manner as the endless belt base 2. The volume resistivity of the test piece prepared by a volume resistance measuring device (Mitsubishi Chemical Corporation, trade name: Hiresta-UP, used probe: URS) under the conditions of a temperature of 23 ° C. and a relative humidity of 50% is prepared. The measured value can be obtained by arithmetic averaging.

  The surface resistivity and volume resistivity of the endless belt substrate 2 can be adjusted by, for example, the type, content, and / or molding conditions of the conductivity imparting agent contained in the resin composition forming the endless belt substrate 2. it can.

  The endless belt base 2 preferably has a surface microhardness of 15 to 30, particularly preferably 20 to 30. When the surface microhardness of the endless belt base 2 is within the above range, the effect of increasing the bending strength and tear strength can be obtained while taking advantage of excellent mechanical properties with a good balance between flexibility and rigidity. The surface microhardness of the endless belt base 2 is the arithmetic average value of the surface microhardness measured by the following method in the following test piece. That is, a plurality of test pieces having a size of 10 mm × 10 mm are cut out from the endless belt base 2, and the surface microhardness meter of each test piece is measured in a measurement environment at a temperature of 23 ° C. and a relative humidity of 50%. (Product name “Dynamic Ultra Micro Hardness Tester (Model“ DUH-W201S ”)”, manufactured by Shimadzu Corporation) is used for measurement under the following measurement conditions. The arithmetic average value of the surface microhardness measured from each test piece is obtained and used as the surface microhardness of the endless belt 1.

<Measurement conditions>
・ Measurement environment: 25 ℃, 50 ± 5% RH
-Test mode: Load-unloading test-Load speed: 3 (0.473988 mN / sec)
・ Indenter type: Triangular pyramid indenter 115 °
・ Test power: 9.8 mN
・ Retention time: 5 sec

  The surface microhardness of the endless belt substrate 2 can be adjusted by the type, content and / or molding conditions of the components contained in the resin composition.

  The endless belt base 2 is formed by curing a resin composition containing a resin. The resin composition is preferably a resin composition having a certain level of strength and containing a single resin or a plurality of types of resins that are resistant to repeated deformation and is highly flexible, and is contained in such a resin composition. Examples of the resin include a thermoplastic resin and a thermosetting resin. Examples of the thermoplastic resin and thermosetting resin include acrylic resin, acrylic / styrene copolymer, polystyrene, acrylonitrile / styrene copolymer, acrylonitrile / butadiene / styrene copolymer (ABS resin), acetyl cellulose, and polyamideimide. Resin (PAI), polyimide resin (PI), polyamide resin (PA), aramid resin, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polyester resins such as cross-linked polyester resin, Fluorine resin, polysulfone resin, polyethersulfone resin (PESF), polycarbonate (PC), polyphenylene oxide (PPO), polyphenylene oxide / polystyrene copolymer, polyphenylene resin Fido (PPS), tetrafluoride resin (PTFE), polymethyl pentene (TPX), polyarylate (PAR), polyacetal (POM), polyetheretherketone (PEEK), epoxy resins, melamine resins, and the like. Among these, thermosetting resins such as polyamideimide resin, polyimide resin, and polyamide resin are preferable, and polyamideimide resin is more preferable. In particular, aromatic polyamideimide resin has strength, flexibility, dimensional stability, and heat resistance. It is preferable in terms of excellent mechanical properties such as a good balance.

  The aromatic polyamideimide resin can be produced by a diisocyanate method in which a tricarboxylic acid anhydride and a diisocyanate compound are reacted, and the diisocyanate method is excellent in terms of availability of raw materials, reactivity and less by-products. . In addition to the aromatic polyamideimide resin produced by the diisocyanate method, an aromatic polyamideimide resin produced using a diamine compound instead of the diisocyanate compound can be used as long as the polycondensation reaction can be suitably advanced. preferable. 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 substrate 2. Moreover, the aromatic polyamide-imide 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.

  The tricarboxylic acid anhydride is preferably an aromatic tricarboxylic acid anhydride, such as trimellitic acid anhydride, 3,4,4′-diphenyl ether tricarboxylic acid anhydride, 3,4,4′-benzophenone tricarboxylic acid anhydride. 2,3,5-pyridinetricarboxylic acid anhydride, naphthalenetricarboxylic acid anhydride, and derivatives thereof. These acid anhydrides can be used alone or in combination of two or more.

  Examples of the tetracarboxylic dianhydride used in place of a part of the tricarboxylic acid anhydride include pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3, 3 ′, 4,4′-biphenyltetracarboxylic 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 dianhydride, ethylenetetracarboxylic dianhydride, and derivatives thereof. These tetracarboxylic dianhydrides may be used alone or in combination of two or more.

  Preferred examples of the diisocyanate compound include aromatic diisocyanate compounds. In addition, as the diisocyanate compound, an aliphatic diisocyanate compound and / or an alicyclic diisocyanate compound, or amines that are derivatives thereof can be used together with or in place of the aromatic diisocyanate compound.

  Examples of aromatic diisocyanate compounds include m-phenylene diisocyanate, p-phenylene diisocyanate, diphenylmethane-4,4′-diisocyanate, 4,4′-diisocyanate diphenyl ether, 4,4′-diisocyanate diphenyl sulfone, and 4,4′-diisocyanate. Biphenyl, 3,3′-dimethyl-4,4′-diisocyanate biphenyl, 2,4-toluene diisocyanate, xylylene diisocyanate and the like can be mentioned. Diamines that are derivatives of these aromatic diisocyanate compounds can also be used as raw materials. Examples of the aliphatic diisocyanate compound include ethylene diisocyanate, propylene diisocyanate, and hexamethylene diisocyanate. Examples of the alicyclic diisocyanate compound include 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and the like. Among these diisocyanate compounds, considering the heat resistance, mechanical properties, solubility, and the like of the endless belt substrate 2, 60% by mass or more, preferably 70% by mass or more of the diisocyanate-4, It is preferable to use diamines that are 4′-diisocyanate, 2,4-toluene diisocyanate, 3,3′-dimethyl-4,4′-diisocyanate biphenyl, isophorone diisocyanate, or derivatives thereof. Furthermore, considering the dimensional stability of the endless belt substrate 2, 70% by mass or more of all diisocyanate compounds used may be diphenylmethane-4,4′-diisocyanate or its derivative 4,4′-diaminodiphenylmethane. More preferred.

  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. Examples of aprotic polar solvents include N, N-dialkylamides, and examples of N, N-dialkylamides include N, N-dimethylformamide, N, N-dimethylacetamide, N, N- Examples include diethylformamide, N, N-diethylacetamide, and N, N-dimethylmethoxyacetamide. Further, as a polar solvent, N-methyl-2-pyrrolidone, pyridine, dimethyl sulfoxide, tetramethylene sulfone, dimethyltetramethylene sulfone, and the like are also preferable. These solvents can be used alone or in combination of two or more.

The resin composition may contain a conductivity imparting agent. Examples of the conductivity imparting agent include conductive powder and ionic conductive material. As the conductive powder, for example, in addition to conductive carbon such as ketjen black and acetylene black, rubber carbons such as SAF, ISAF, HAF, FEF, GPF, SRF, FT and MT, titanium oxide, and oxidation Examples thereof include metals such as zinc, nickel, copper, silver, germanium, metal oxides, conductive polymers such as polyaniline, polypyrrole, and polyacetylene, and nanoparticles. Examples of the ion conductive material include inorganic ionic conductive materials such as sodium perchlorate, lithium perchlorate, calcium perchlorate, and lithium chloride. Among these, conductive carbon and carbon for rubber are preferable, and carbon black is particularly preferable. As the conductivity-imparting agent, one of these various substances can be used alone, or two or more of them can be used in combination. A preferable shape of the conductivity-imparting agent is spherical or irregular. The size of the particles of the conductivity-imparting agent having a spherical or irregular shape is preferably about 0.01 to 10 μm as the primary particle diameter. If conductive agent is carbon black, the BET specific surface area, strong correlation between the primary particle diameter is preferably ^{50~300m 2 / g, 100~200m 2 /} g is more preferable.

  The content of the conductivity-imparting agent in the resin composition may be appropriately adjusted according to the conductivity and particle size of the conductivity-imparting agent, the conductivity characteristics required for the endless belt base 2, and the like. It is preferably 1 to 25% by mass, more preferably 5 to 20% by mass, and particularly preferably 10 to 20% by mass with respect to 100% of the total mass of the product and the conductivity-imparting agent. . If the addition amount of the conductivity imparting agent is less than 1% by mass, the distance between the conductive materials may be too long, and the expression of conductivity in the endless belt base 2 may be deteriorated. On the other hand, the addition amount of the conductivity imparting agent may be reduced. If it exceeds 25 mass%, the mechanical strength of the endless belt base 2 may be lowered. In order to disperse the conductivity-imparting agent in the resin, a known method can be appropriately selected. Examples of known methods include mixing rolls, pressure kneaders, extruders, three rolls, homogenizers, ball mills, pot mills, and the like. The mixing method using bead mill etc. is mentioned.

  Unless the objective of this invention is inhibited, the resin composition may contain other components in addition to the resin and the conductivity imparting agent. Examples of other components include silicone compounds, fluorine organic compounds, coupling agents, lubricants, antioxidants, plasticizers, colorants, antistatic agents, anti-aging agents, reinforcing fillers, reaction aids, Examples include various additives such as reaction inhibitors. The resin composition may contain other resins as long as the object of the present invention is not impaired. The content of these other components in the resin composition can be appropriately determined according to the characteristics developed in the resin composition by the addition of these other components.

  As shown in FIG. 1, the elastic layer 3 is formed by curing a rubber composition, which will be described later, on the outer peripheral surface of the endless belt base 2 and has a single layer structure. Therefore, the elastic layer 3 has the same inner peripheral diameter as the outer peripheral diameter of the endless belt base 2 and has the same width as the width of the endless belt base 2. The thickness of the elastic layer 3 should just be adjusted to the thickness which has elasticity with the rubber composition mentioned later, Usually, it is preferable that it is 50-400 micrometers, it is more preferable that it is 70-300 micrometers, and 100-250 micrometers. Is particularly preferred. When the thickness of the elastic layer 3 is within the above range, when the endless belt 1 is mounted on the image forming apparatus, a contact width between the endless belt 1 and a member with which the endless belt 1 contacts is secured, and development is performed. Good transferability of the agent can be realized. The thickness of the elastic layer 3 can be measured in the same manner as the thickness of the endless belt base 2.

The elastic layer 3 preferably has a surface resistivity of 1 × 10 ⁹ to 1 × 10 ¹³ Ω / □, and has a surface resistivity of 1 × 10 ¹⁰ to 1 × 10 ¹³ Ω / □. More preferably, it has a surface resistivity of 1 × 10 ¹⁰ to 1 × 10 ¹² Ω / □. When the surface resistivity is within the above range, a high-quality image can be formed when the endless belt 1 having the elastic layer 3 is used in an image forming apparatus. For the surface resistivity, a test piece corresponding to the elastic layer 3 such as the elastic layer 3 or a test piece cut out from the elastic layer 3 or a test piece produced in the same manner as the elastic layer 3 is prepared. It is measured in the same manner as the surface resistivity.

The elastic layer 3 preferably has a volume resistivity of 1 × 10 ⁸ to 1 × 10 ¹² Ω · cm, and has a volume resistivity of 1 × 10 ⁹ to 1 × 10 ¹² Ω · cm. More preferably, it has a volume resistivity of 1 × 10 ⁹ to 1 × 10 ¹¹ Ω · cm. When the volume resistivity is within the above range, a high-quality image can be formed when the endless belt 1 including the elastic layer 3 is used in an image forming apparatus. For the volume resistivity, the elastic layer 3 or a test piece corresponding to the elastic layer 3 such as a test piece cut out from the elastic layer 3 or a test piece produced in the same manner as the elastic layer 3 is prepared. The volume resistivity is measured in the same manner. The surface resistivity and volume resistivity of the elastic layer 3 can be adjusted by, for example, the type, content and / or molding conditions of the conductivity imparting agent contained in the rubber composition forming the elastic layer 3.

  The elastic layer 3 preferably has elasticity, for example, generally preferably has a JIS A hardness of 40 to 90, and preferably has a JIS A hardness of 50 to 80. More preferably, it has a JIS A hardness of 50 to 70. When the elastic layer 3 has a JIS A hardness within the above range, a sufficient contact width between the endless belt 1 and a member with which the endless belt 1 contacts when the endless belt 1 is attached to the image forming apparatus. Can be secured. The JIS A hardness of the elastic layer 3 can be a value obtained by measuring a test piece obtained by molding a rubber composition used to form the elastic layer 3 to a constant thickness in accordance with JIS K6301. The JIS A hardness of the elastic layer 3 can be adjusted by, for example, the type, content and / or molding conditions of the conductivity imparting agent.

  The elastic layer 3 preferably has a static friction coefficient in the range of 0.7 to 1.7 in the following measurement method, and preferably in the range of 0.9 to 1.5. When the static friction coefficient of the elastic layer 3 is within the above range, the developer is more excellent in the releasability of the developer in the elastic layer 3, and the charged developer is desired from the elastic layer 3 of the endless belt 1 to the recording medium or the like. And the elastic layer 3 slides on the cleaning blade pressed against the endless belt 1 to prevent the cleaning blade from turning back in the running direction of the endless belt 1 for a long period of time. it can. If the cleaning blade can be prevented from turning over for a long period of time, the developer remaining on the elastic layer 3 can be cleaned without applying an excessive load to the cleaning blade. The static friction coefficient of the elastic layer 3 can be adjusted within the above range by, for example, the type and / or content of silica and / or fluororesin contained in the elastic layer 3.

  The static friction coefficient on the surface of the elastic layer 3 is measured as follows. First, a urethane thermoplastic resin blade having a thickness of 1.5 mm, a width of 13 mm, and a length of 40 mm and having the following physical properties (I) to (IV) has a height of 77 mm, a width of 54 mm, and a length. Double-sided tape (trade name “double-sided tape and fastener”, Sumitomo 3M Limited) so that a width of 8 mm and a length of 40 mm overlap with a 60 mm plate-like aluminum support 52 (made by Shinto Kagaku Co., Ltd.). To make a test blade. One end edge of the tip of the urethane thermoplastic resin blade in this test blade is set so that the contact angle θ with respect to the surface of the elastic layer 3 is 23 °, the contact width is 40 mm, and the load is 100 g. The test blade is moved at a constant speed in the circumferential direction of the elastic layer 3 under the condition of a speed of 120 mm / min while maintaining the contact state in an environment of 23 ° C. and a relative humidity of 50%. The static friction coefficient generated at this time is measured using a surface property measuring device (trade name “HEIDON-14D” manufactured by Shinto Kagaku Co., Ltd.). This operation is performed a plurality of times, for example, five times, and the arithmetic average value thereof is set as the static friction coefficient.

(I) JIS A hardness: 73
(II) Elongation (Measurement is based on JIS K6251 (using dumbbell-shaped No. 3 test piece)): 320%
(III) 300% modulus (measurement method is defined in JIS K6251 (2004 edition)): 160 kg / cm ²
(IV) Tensile strength (JIS Z2241): 200 kg / cm ²

  The elastic layer 3 contains silica. When silica is contained in the elastic layer 3, the coefficient of static friction of the elastic layer 3 can be reduced without impairing the flexibility (followability) of the elastic layer 3, and as a result, the developer in the elastic layer 3 can be reduced. The releasability is improved and the initial pressure contact state between the endless belt 1 and the cleaning blade can be maintained for a long period of time. Although the reason is not clear in detail, it is thought that a part of silica particle exists in the surface of the elastic layer 3, and the surface layer of the elastic layer 3 becomes uneven | corrugated by this silica, and a static friction coefficient falls. Examples of the silica include hydrophobic silica and hydrophilic silica.

  The silica preferably has an amorphous content of 5 to 50% by mass. The amorphous content of the silica is subjected to X-ray diffraction analysis of the sample in the range of 2θ of CuKα ray of 26 ° to 27.5 ° using a powder X-ray diffractometer (for example, model Mini Flex; manufactured by RIGAKU). It can be measured from the intensity ratio of the specific diffraction peak. For example, in the case of silica, the main peak is present at 26.7 ° in the crystal component, but no peak is present in the non-crystal component. If the non-crystal component and the crystal component are mixed, 26 corresponding to the ratio thereof is obtained. Since the peak height of 7 ° is obtained, the ratio of the X-ray intensity of the sample to the X-ray intensity of the standard sample of the silica content of the crystal is calculated from the ratio of the mixed silica of the crystal content (X-ray diffraction intensity of the sample / X-ray of the silica of the crystal content). (Diffraction intensity) is calculated, and the amorphous content can be obtained from “amorphous content (mass%) = (1-crystal content silica mixing ratio) × 100”. The shape of the silica is not particularly limited, but is preferably spherical or elliptical, and has an average particle size of 0.1 to 20 μm, and is uniformly dispersed in the urethane constituting the elastic layer 3. It is further preferable in that The average particle diameter of the silica was measured using a 50 μm aperture tube using the Coulter counter method (trade name “Coulter Multisizer II” (manufactured by Coulter Co., Ltd.)). % Value is an average particle diameter).

  The content of silica in the elastic layer 3 is preferably 1 to 50 parts by mass, more preferably 5 to 45 parts by mass, and more preferably 10 to 40 parts by mass with respect to 100 parts by mass of the urethane forming the elastic layer 3. Part by mass is particularly preferred. When the content of silica is in the above range, the endless belt 1 provided with the elastic layer 3 is excellent in the releasability of the developer and can maintain the pressure contact state for a long period of time.

  The elastic layer 3 may contain a fluororesin. When the elastic layer 3 contains a fluororesin, the releasability of the developer in the elastic layer 3 is improved without greatly impairing the flexibility (following property) of the elastic layer 3, and the endless belt 1 and cleaning are performed. The initial pressure contact state with the blade can be maintained for a long period of time. The fluororesin may be a resin in which a linear hydrocarbon chain is the main chain and part or all of the hydrogen atoms are replaced with fluorine atoms. For example, polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexa A fluoropropylene copolymer (PFEP), a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), etc. are mentioned. The fluororesin is contained in the elastic layer 3 singly or in combination of two or more.

  The fluororesin is preferably contained as particles. When the fluororesin is contained in the elastic layer 3 as particles, the releasability of the developer in the elastic layer 3 is further improved, and the initial pressure contact state between the endless belt 1 and the cleaning blade is maintained for a long period of time. can do. The shape of the fluororesin particles is not particularly limited, but is preferably spherical or elliptical. The average particle diameter of the fluororesin particles is preferably from 0.1 to 20 μm from the viewpoint that it can be uniformly dispersed in the urethane constituting the elastic layer 3. The average particle diameter of the fluororesin particles can be measured by a laser scattering (50% average particle diameter) method.

  The content of the fluororesin in the elastic layer 3 is preferably 1 to 40 parts by mass, more preferably 1 to 35 parts by mass with respect to 100 parts by mass of urethane forming the elastic layer 3. The amount is particularly preferably 25 parts by mass. When the content of the fluororesin in the elastic layer 3 is in the above range, the endless belt 1 provided with the elastic layer 3 is excellent in the releasability of the developer and can maintain the pressure contact state for a long time.

  The elastic layer 3 is formed by curing a urethane composition. This urethane composition contains a polyurethane preparation component and silica, and optionally contains a fluororesin and various additives. When the elastic layer 3 is formed of a urethane composition, a member such as an image carrier that the endless belt 1 contacts when the endless belt 1 is attached to the image forming apparatus is contaminated with its constituent components or low molecular weight components. As a result, it is possible to contribute to forming a high-quality image. In the endless belt according to the present invention, since the elastic layer 3 is formed of a urethane composition, even if it is used as an intermediate transfer belt, the image carrier and the recording medium are contaminated and the releasability of the developer is improved. There is no inferiority.

  The polyurethane preparation component may be any component that can form polyurethane. For example, a mixture of polyol and polyisocyanate, a prepolymer obtained by reacting polyol and polyisocyanate, and polyol and polyisocyanate are mixed. Examples thereof include at least one component selected from the group consisting of polyurethane obtained by reaction.

  The polyol in the mixture of polyol and polyisocyanate may be any of various polyols usually used in the preparation of polyurethane, but at least one polyol selected from polyether polyol and polyester polyol is elastic. It is preferable at the point which is excellent in the abrasion resistance of the layer 3, etc. Examples of the polyether polyol include polyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polypropylene glycol-ethylene glycol, polytetramethylene ether glycol, copolymer polyols of tetrahydrofuran and alkylene oxide, and various modified products thereof. These mixtures etc. are mentioned. Examples of the polyester polyol include condensed polyester polyols, lactone polyester polyols, polycarbonate polyols, and mixtures thereof obtained by condensation of dicarboxylic acids such as adipic acid and polyols such as ethylene glycol. The polyether polyol and polyester polyol may be used singly or in combination of two or more, or a polyether polyol and a polyester polyol may be used in combination. The polyol is preferably a polyester polyol because it is excellent in thermal stability. The polyol preferably has a number average molecular weight of 1000 to 8000, more preferably 1000 to 5000, in view of excellent compatibility with polyisocyanate and the like described later. The number average molecular weight is a molecular weight when converted to standard polystyrene by gel permeation chromatography (GPC).

  The polyisocyanate in the mixture of polyol and polyisocyanate may be any of various polyisocyanates usually used in the preparation of polyurethane, and examples thereof include aliphatic polyisocyanates and aromatic polyisocyanates. The polyisocyanate is preferably an aromatic polyisocyanate in terms of excellent storage stability and easy control of the reaction rate. Examples of the aromatic polyisocyanate include xylylene diisocyanate (XDI), diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), naphthalene diisocyanate (NDI), paraphenylene diisocyanate (PDI), and tolidine diisocyanate (TODI). It is done. Examples of the aliphatic polyisocyanate include hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), norbornane diisocyanate methyl, transcyclohexane-1,4-diisocyanate, and hydrogenated MDI.

  In addition to these polyisocyanates, block polyisocyanates in which isocyanate groups are blocked with a blocking agent are preferably used as the polyisocyanate. Block polyisocyanate has high stability at room temperature and has advantages such as easy handling because the blocking agent is released by heating and the isocyanate group is regenerated. In particular, it has an advantage that it reacts stably even in summer when the humidity is high, and can be used in combination with a reagent having an active group having a high reactivity such as an amino group. Examples of the blocking agent include ε-caprolactams, methyl ethyl ketoximes, 3,5-dimethylpyrazoles, alcohols and phenols. Examples of the blocking agent include isocyanates. In this case, the blocked polyisocyanate is a polyisocyanate dimer (polyuretdione). As the blocking agent, any of the above can be used, but ε-caprolactams and methyl ethyl ketoximes are preferred from the viewpoint of excellent compatibility with the solvent. The blocked isocyanate can be arbitrarily combined with the isocyanate and the blocking agent. For example, blocked polyisocyanate obtained by reacting diphenylmethane diisocyanate (MDI) and ε-caprolactam, toluene diisocyanate (TDI) and ε- Block polyisocyanate obtained by reacting caprolactam, block polyisocyanate obtained by reacting diphenylmethane diisocyanate (MDI) and methyl ethyl ketoxime, and the like are preferable.

  The mixing ratio in the mixture of polyol and polyisocyanate is not particularly limited. Usually, the hydroxyl group (OH) contained in the polyol and the isocyanate group contained in the polyisocyanate (NCO, an isocyanate group that can be liberated in the case of block polyisocyanate). ) Is preferably 0.7 to 1.15 in that the desired degree of crosslinking in the resulting polyurethane can be achieved. This molar ratio (NCO / OH) is more preferably 0.85 to 1.10. From the viewpoint that hydrolysis of polyurethane can be prevented.

  In a mixture of a polyol and a polyisocyanate, the composition contains, in addition to the polyol and the polyisocyanate, auxiliary agents usually used for the reaction of the polyol and the polyisocyanate, such as a chain extender and a crosslinking agent. Also good. Examples of chain extenders and crosslinking agents include glycols, hexanetriol, trimethylolpropane, and amines.

  The prepolymer and the polyurethane may be any prepolymer and polyurethane obtained by reacting the polyol and the polyisocyanate, and the molecular weight thereof is not particularly limited. The prepolymer and the polyurethane can be obtained by reacting a polyol and a polyisocyanate, for example, in the molar ratio by a one-shot method or a prepolymer method in the presence of the auxiliary agent, if desired.

  The polyurethane preparation component is preferably a mixture of polyol and polyisocyanate, particularly preferably a mixture of at least one polyol selected from polyether polyol and polyester polyol and polyisocyanate. That is, the composition particularly preferably contains a mixture of at least one polyol selected from polyether polyol and polyester polyol and polyisocyanate.

  The silica and fluororesin contained in the urethane composition are basically the same as the silica and fluororesin contained in the elastic layer 3.

  The content of silica in the urethane composition is preferably 1 to 50 parts by mass, more preferably 5 to 45 parts by mass, with respect to 100 parts by mass of the polyurethane preparation component, and 10 to 40 parts by mass. Is particularly preferred. When the content of silica in the urethane composition is in the above range, it is possible to form the elastic layer 3 that is excellent in the releasability of the developer and can maintain the pressure contact state for a long period of time. The content of the fluororesin in the urethane composition is preferably 1 to 40 parts by weight, more preferably 1 to 35 parts by weight, and more preferably 1 to 25 parts by weight with respect to 100 parts by weight of the polyurethane preparation component. Part is particularly preferred. When the content of the fluororesin in the urethane composition is in the above range, it is possible to form the elastic layer 3 that has excellent developer releasability and can maintain the pressure contact state for a long period of time.

  The urethane composition may usually contain various additives contained in the composition as long as the object of the present invention is not impaired. Examples of the various additives include the chain extender and the crosslinking agent. Aids, dispersants, foaming agents, anti-aging agents, antioxidants, fillers, pigments, colorants, processing aids, softeners, plasticizers, emulsifiers, curing agents, heat resistance improvers, flame retardant improvements Agents, acid acceptors, thermal conductivity improvers, mold release agents, solvents and the like. These various additives may be commonly used additives or may be specially used additives depending on applications.

  The urethane composition is prepared by using a rubber kneader such as a two-roller, a three-roller, a roll mill, a Banbury mixer, a dough mixer (kneader), etc., to prepare polyurethane preparation components and silica, and optionally fluoropolymer particles and various additives. It is obtained by kneading, for example, for several minutes to several hours, preferably 5 minutes to 1 hour, at room temperature or under heating until uniformly mixed.

  Next, a method for manufacturing an endless belt according to the present invention will be described. In order to manufacture the endless belt according to the present invention, the resin composition for forming the endless belt base 2 and the rubber composition for forming the elastic layer 3 are respectively prepared as described above.

  The prepared resin composition is molded into a ring shape by a known molding method. For example, when a thermoplastic resin is selected as the resin contained in the resin composition, centrifugal molding, extrusion molding, injection molding, etc., while when a thermosetting resin is selected as the resin, centrifugal molding, The endless belt base 2 can be molded by 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 endless belt base 2 is molded by centrifugal molding, the resin composition preferably has a viscosity during molding of 50,000 mPa · s or less. When the viscosity exceeds 50,000 mPa · s, it may be difficult to produce the endless belt base 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 or more. 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. As a solvent, the solvent used for the polycondensation reaction which synthesize | combines the said aromatic polyamideimide resin is mentioned.

  According to centrifugal molding, a resin composition that exhibits fluidity by containing a solvent is poured into a cylindrical mold, and the mold is rotated to form a resin composition layer on the inner peripheral surface of the mold by centrifugal force. The endless belt molded body is produced by uniformly spreading and drying and removing the solvent from the resin composition layer. 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 a mirror surface is subjected to mold release treatment with a release agent such as fluororesin or silicone resin, and is formed as an endless belt molded body Is a metal tube that can be easily removed from the inner peripheral surface.

  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, An endless belt molded body can also be produced by JP-A 64-22514, JP-A 3-180309, and the like.

  The solvent is removed from the layer of the resin composition developed on the inner peripheral surface of the mold to produce an endless belt molded body. Here, the solvent to be removed is a solvent contained in the layer of the resin composition developed on the inner peripheral surface of the mold. For example, in addition to the solvent used when adjusting the viscosity of the resin composition And a solvent used when synthesizing the aromatic polyamideimide resin. Examples of the treatment for removing the solvent from the resin composition layer developed on the inner peripheral surface of the mold include a heat treatment. To remove the solvent, the following primary solvent removal step and secondary solvent removal step are used. It is preferable to perform a solvent removal treatment consisting of

  In the primary solvent removing step, molding is performed while removing the solvent from the resin composition layer developed on the inner peripheral surface of the mold by rotating the mold, and the resin composition layer is used as a film-shaped molded body. In the primary solvent removal step, the solvent is removed by passing hot air of 40 to 150 ° C. through the mold for 5 to 60 minutes while rotating the mold. When the hot air temperature exceeds 150 ° C. and / or when the heating time exceeds 60 minutes, the molded film-like molded body may be oxidized.

  In the secondary solvent removal step, the film-like molded body molded in the primary solvent removal step is taken out from the centrifugal molding machine together with the mold, heated together with the mold, the solvent is removed from the film-like molded body, and the endless belt molded body And For example, when using a heater such as a hot air dryer or oven, the film-like molded body may be heated together with the mold at 200 to 300 ° C. for 1 to 3 hours, and when a superheated steam furnace is used. What is necessary is just to heat a film-like molded object for 0.5 to 3 hours with 200-260 degreeC superheated steam with a metal mold | die. In addition, if a deformation | transformation etc. of a film molded object can be prevented, a film molded object can be demolded from a metal mold | die, and it can also heat on the said conditions.

  After producing an endless belt molded body from which the solvent has been removed in this manner, the endless belt molded body is taken out of the mold and allowed to cool. When the endless belt molded body is allowed to cool together with the mold, the endless belt molded body can be removed due to the difference in thermal expansion coefficient between the mold and the endless belt molded body.

  In this way, the endless belt molded body is removed from the mold, both end portions of the annular endless belt molded body are removed, and the endless belt base body 2 is manufactured by cutting to a predetermined width. The cutting machine for cutting the endless belt molded body may be an apparatus capable of cutting so that the cutting start point and the cutting end point of the endless belt molded body substantially coincide with each other.

  The urethane composition is applied to the outer peripheral surface of the endless belt base 2 thus produced. The urethane composition is applied by a normal application method, for example, a dipping method, a spray method, a roll coater method, a doctor blade coating method, etc., with a coating amount such that the thickness of the elastic layer 3 after curing is within the above range, Applied. Next, the urethane composition applied to the outer peripheral surface of the endless belt base 2 is cured. The urethane composition is cured by moisture and / or heating. As for moisture hardening conditions, 10 to 70% of conditions are mentioned, for example. As for the heating conditions, for example, the heating temperature when the urethane resin composition is heated and cured is, for example, 50 to 150 ° C., particularly 100 to 150 ° C., and the heating time is 30 to 120 minutes, particularly 60 to 90 minutes. preferable. The elastic layer 3 thus formed may have its surface polished or ground as desired.

  Since the endless belt 1 manufactured in this manner includes the elastic layer 3 containing silica as a surface layer on the outer peripheral surface of the endless belt base 2, the release property of the developer in the urethane elastic layer 3 is improved. be able to. Further, since the endless belt 1 includes the elastic layer 3 containing silica as a surface layer on the outer peripheral surface of the endless belt base 2, the endless belt 1 slides on the pressure-contacted cleaning blade so that the cleaning blade travels on the endless belt 1. It is possible to prevent turning back in the direction. As a result, the endless belt 1 can maintain the initial pressure contact state with the cleaning blade for a long period of time. Further, even when the endless belt 1 travels, the developer remaining in the elastic layer 3 can be cleaned as desired without applying an excessive load to the cleaning blade.

  Since the endless belt 1 is excellent in the releasability of the developer and can maintain the initial pressure contact state with the cleaning blade for a long period of time, the endless belt 1 has a function of removing the adhering developer. It is suitably used in an image forming apparatus having a cleaning blade whose edge is pressed against the endless belt 1. In particular, the endless belt 1 includes the cleaning blade, and is preferably used for an image forming apparatus in which the printing speed, that is, the traveling speed of the endless belt is increased.

  As an endless belt mounted on such an image forming apparatus, for example, a conveyance belt that conveys a recording medium, a transfer belt that contributes to the transfer of the developer to the recording medium, a developer that conveys the recording medium and also develops the recording medium Transfer belt that contributes to the transfer of toner, a development belt that supplies developer to the image carrier, a transfer belt that fixes the developer transferred to the recording body, a photosensitive belt that carries the developer image, and the like. In particular, an intermediate transfer belt that receives the developer from the image carrier (primary transfer) and supplies the developer once carried to the recording medium (secondary transfer) is preferable.

  As described above, the endless belt 1 has excellent developer releasability and can maintain the initial pressure contact state with the cleaning blade for a long period of time. It can contribute to forming an image. In particular, an image forming apparatus capable of forming a high-definition image, an image forming apparatus capable of forming an image at high speed, and an image forming apparatus capable of forming a high-definition image at high speed Even if it is mounted on the printer, it will make a significant contribution to the stable formation of images with the desired high quality over a long period of time, while maintaining a high developer releasability and maintaining the pressure contact state for a long period of time. can do. Therefore, according to the present invention, even if it is mounted on a recent high-definition image forming apparatus, a recent high-speed image forming apparatus, or a recent downsized and light-weight image forming apparatus, the desired high quality It is possible to achieve the object of providing an endless belt capable of stably forming an image having a long period of time.

  The endless belt according to the present invention is not limited to the above-described embodiments, and various modifications can be made within a range in which the object of the present invention can be achieved. For example, the endless belt base 2 and the elastic layer 3 of the endless belt 1 both have a single layer structure. In the present invention, the endless belt base and / or the elastic layer of the endless belt is a multilayer in which two or more layers are laminated. It may be a structure.

  In the endless belt 1, the elastic layer 3 is formed on the outer peripheral surface of the endless belt base 2. In the present invention, the adhesive layer or the primer layer is formed on the outer peripheral surface of the endless belt base 2. The elastic layer 3 may be formed on the outer peripheral surface of the adhesive layer or the primer layer. Further, the endless belt 1 includes an endless belt base 2 and an elastic layer 3, and the elastic layer 3 is a surface layer. In the present invention, the endless belt is disposed on the outer peripheral surface of the elastic layer on the outer peripheral surface of the elastic layer as desired. It may have a surface layer formed of resin particles or the like, and the fluororesin particles may adhere to the outer peripheral surface of the elastic layer.

  Further, the endless belt 1 includes an endless belt base 2 and an elastic layer 3. In the present invention, the endless belt is an inner peripheral surface of the endless belt base and, in the axial direction of the endless belt base, as desired. At least one end may be provided with a string-like or belt-like elongated guide member formed of an elastic material. This guide member functions as a guide for preventing side shake while the endless belt is running. Examples of the material for the guide member include elastic materials having appropriate rubber elasticity and wear resistance, such as urethane elastomers, silicone elastomers, fluororesin elastomers, and styrene elastomers. Among these, urethane-based elastomers having an A hardness of 30 or more and 95 or less according to JIS K 6253-1997, which is excellent in wear resistance, are preferable. Preferably, the guide member is provided so as to go around the inner peripheral surface of the endless belt base at both ends in the axial direction of the endless belt base.

  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. The image forming apparatus 10 is an intermediate transfer type tandem color image forming apparatus. An intermediate transfer tandem color image forming apparatus 10 is basically configured in the same manner as a conventionally known image forming apparatus, but an endless belt 1 according to the present invention is mounted as an intermediate transfer belt 7.

  As shown in FIG. 2, the image forming apparatus 10 includes an intermediate transfer belt 7 wound around two support rollers 42 and traveling on an endless track in the direction of the arrow in FIG. 2, and the traveling direction of the endless track. And a cleaning blade 51 that is disposed on the downstream side of the secondary transfer portion 40 and presses against the outer peripheral surface of the intermediate transfer belt 7. The endless belt 1 is stretched around two support rollers 42, a tension roller 43, and a counter roller 44 as an intermediate transfer belt. In the vicinity of the position where the counter roller 44 is installed, a secondary transfer unit 40 including a counter roller 44, a secondary transfer roller 45, and an electrode roller 46 is disposed.

  As shown in FIG. 2, in the image forming apparatus 10, four types of developing units B, C, M, and Y are arranged in series on the intermediate transfer belt 7. The developing unit B includes an image carrier 11B such as a photosensitive member, a charging roller 12B, an exposure unit 13B, a developing roller 23B, a developing unit 20B including a housing 21B, a transfer roller 14B, and an image carrier cleaning blade 15B. ing. The developing unit B contains a black developer. The developing units C, M, and Y are configured in the same manner as the developing unit B, and contain a cyan developer 22C, a magenta developer 22M, and a yellow developer 22Y.

  As shown in FIG. 2, a fixing unit 30 having an endless belt 35 as a fixing belt is disposed downstream in the conveyance direction of the recording medium 16 in the image forming apparatus 10. The fixing device 30 is a pressure heat fixing device including a fixing roller 31, a support roller 33, a fixing belt 35, and a pressure roller 32 in a housing 34 having an opening. The fixing unit 30 may be a heat roller fixing device, a heat fixing device, a pressure fixing device, or the like.

  As shown in FIGS. 2 and 4, the cleaning blade 51 includes a support body 52 and an elastic body 53. The cleaning blade 51 preferably has a compression set (JIS K6301, 60 ° C., 48 hours) in the range of 0.1 to 20%.

  As shown in FIG. 4, the support 52 has a plate-like portion 55 extending in one direction, and substantially extends from one end edge to the plate-like portion 55 along one longitudinal edge of the plate-like portion 55. The mounting portion 56 is formed so as to extend vertically. That is, the support body 52 is formed as a plate-like member having a substantially L-shaped cross section in a cross section perpendicular to the longitudinal direction. The support body 52 supports an elastic body 53 to be described later, and makes the elastic body 53 contact the intermediate transfer belt 7 with a desired pressing force. Therefore, the support body 52 is formed of a material that can support the elastic body 53, such as a metal material. In general, the support 52 preferably has a thickness of 50 to 250 μm, and particularly preferably has a thickness of 80 to 120 μm. The support 52 preferably has a uniform thickness over the entire surface. The support 52 is adjusted such that the length in the longitudinal direction is longer than the length in the width direction of the intermediate transfer belt 7.

  The elastic body 53 can be formed in an arbitrary shape. For example, as shown in FIGS. 2 and 4, the elastic body 53 is formed in a rectangular plate shape or a rectangular parallelepiped having a predetermined thickness. The elastic body 53 has an end or an edge (referred to as a front end pressure contact portion) abutted against the intermediate transfer belt 7 with a desired pressing force, and slides on the intermediate transfer belt 7. As described above, the tip press-contact portion of the elastic body 53 contacts the elastic layer 3 of the intermediate transfer belt 7, so that the developer and the like attached to the elastic layer 3 of the intermediate transfer belt 7 can be effectively removed.

  The elastic body 53 is formed of an elastic material having elasticity, such as urethane rubber or silicone rubber so as not to damage the intermediate transfer belt 7. Examples of the urethane rubber include thermoplastic urethane rubber. More specifically, urethane rubber using polyester polyol and polyether polyol as a polyol component, and tolylene diisocyanate, diphenylmethane diisocyanate, and an isocyanate component. Examples include urethane rubber using hexamethylene diisocyanate and the like. Examples of the silicone rubber include HTV rubber (high-temperature curable millable silicone rubber, etc.), liquid silicone rubber (LTV, RTV, etc.), and the like.

  The thickness of the elastic body 53 is adjusted to an arbitrary thickness, specifically 0.1 to 3 mm. The elastic body 53 preferably has a uniform thickness over the entire surface. Further, like the support body 52, the elastic body 53 is preferably adjusted so that the length in the longitudinal direction is longer than the length in the width direction of the intermediate transfer belt 7. The length in the direction perpendicular to is not particularly limited, and is adjusted to about 10 to 30 mm, for example.

Since the elastic body 53 is in pressure contact with the intermediate transfer belt 7, the JIS A hardness is preferably in the range of 60 to 80, and particularly preferably in the range of 60 to 75. Also, 100% modulus (JIS K6251 (2004 edition)) is 20-30 kg / cm ² , 300% modulus (JIS K6251 (2004 edition)) is 100-200 kg / cm ² , and elongation (JIS K6251 (dumbbell-shaped 3) It is preferable that the shape test piece use)) is 300 to 320%, and the tensile strength (JIS Z2241) is 200 kg / cm ² or more.

  Since the elastic body 53 removes the developer attached to the outer surface of the intermediate transfer belt 7, the amount of wear measured by JIS-K7311 (load 1 kg, wear wheel H-22; 1000 revolutions) is 50 mg or less. It is preferable that it is 30 mg or less.

  In the cleaning blade 51, the support body 52 and the elastic body 53 are respectively made of the above-described materials by a known method, and if desired, an adhesive is applied to the support body 52, and the elastic body 53 is overlaid on the applied adhesive. It can be produced by curing the adhesive by a known method.

  The cleaning blade 51 only needs to have its front end pressure contact portion in pressure contact with the elastic layer 3 of the intermediate transfer belt 7. In other words, the front end pressure contact portion extends along the axis of the intermediate transfer belt 7 in the running direction of the intermediate transfer belt 7. It is preferable that the contact is made so as to be substantially perpendicular to the surface.

  As shown in FIGS. 2 and 4, the cleaning blade 51 has a pressure contact angle formed between a virtual extension line in the width direction of the elastic body 53 and the running surface of the intermediate transfer belt 7 in a state where the cleaning blade 51 is not in contact. The image forming apparatus 10 is preferably mounted so that θ (see FIG. 2) is in a range of 15 ° to 25 °. The cleaning blade 51 preferably presses the intermediate transfer belt 7 with a pressure P of 0.2 to 2 MPa so that the pressure angle θ is the same. When the cleaning blade 51 is mounted so as to have the pressure contact angle θ and the pressure contact pressure P, the pressure contact state with the intermediate transfer belt 7 can be maintained over a long period of time, and is attached to the outer peripheral surface of the intermediate transfer belt 7. The developed developer can be removed as desired. As shown in FIG. 2, the cleaning blade 51 has a support member for the elastic body 53 on the upstream side with respect to the traveling direction of the intermediate transfer belt 7 (the direction indicated by the arrow in FIG. 2). It is preferable that the 52 side is disposed on the downstream side with respect to the traveling direction of the intermediate transfer belt 7. When the cleaning blade 51 is arranged in this way, the elastic body 53 comes into pressure contact with the intermediate transfer belt 7 from the direction opposite to the traveling direction of the intermediate transfer belt 7, so that the developer can be highly removed.

  The image forming apparatus 10 forms an image as follows. First, the developing unit B visualizes the electrostatic latent image on the surface of the image carrier 11B as a developer image with the black developer 22B, and the developer image is transferred onto the intermediate transfer belt 7 (primary transfer). Subsequently, the developer image is transferred to the intermediate transfer belt 7 by the developing units C, M, and Y, and a color image is formed. The color image reaches the secondary transfer unit 40 by the rotation of the intermediate transfer belt 7 and is transferred onto the recording medium 16 conveyed to the secondary transfer unit 40 (secondary transfer). Next, the recording medium 16 in which the color image is visualized is conveyed to the fixing unit 30 and the color image is fixed as a permanent image. The developer remaining on the surface of the intermediate transfer belt 7 that has passed through the secondary transfer portion 40 is removed by the cleaning blade 51 disposed downstream. In this way, a color image is formed on the recording medium 16. Although the case where a color image is formed using the image forming apparatus 10 has been described, in the case of forming a monochrome image, the developer image primarily transferred to the intermediate transfer belt 7 is immediately secondary transferred to the recording medium 16. Then, it may be conveyed to the fixing means 30.

  Another 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. The image forming apparatus 50 is an intermediate transfer type multi-pass color image forming apparatus. The intermediate transfer type multi-pass color image forming apparatus 50 is basically configured in the same manner as a conventionally known image forming apparatus, but an endless belt 1 according to the present invention is mounted as an intermediate transfer belt 7.

  As shown in FIG. 3, the image forming apparatus 50 includes an intermediate transfer belt 7 wound around two support rollers 42 and traveling on an endless track in the direction of the arrow in FIG. 3, and the travel direction of the endless track. And a cleaning blade 51 that is disposed on the downstream side of the secondary transfer portion 40 and presses against the outer peripheral surface of the intermediate transfer belt 7. The endless belt 1 is stretched around two support rollers 42, a tension roller 43, and a counter roller 44 as an intermediate transfer belt. In the vicinity of the position where the counter roller 44 is installed, a secondary transfer unit 40 including a counter roller 44, a secondary transfer roller 45, and an electrode roller 46 is disposed.

  As shown in FIG. 3, the image forming apparatus 50 includes a developing unit 20 including four types of developing units B, C, M, and Y. The developing units B, C, M, and Y built in the developing unit 20 include a charging unit, an exposure unit, and the like, and store a black developer, a cyan developer, a magenta developer, and a yellow developer, respectively. The developing unit 20 may include a charging unit, an exposing unit, and the like outside the developing unit 20 and in the vicinity of the image carrier 11.

  As shown in FIG. 3, a fixing unit 30 is disposed downstream in the conveyance direction of the recording body 16 in the image forming apparatus 50. The fixing device 30 is configured in the same manner as the fixing device 30 of the image forming apparatus 10.

  As shown in FIGS. 3 and 4, the cleaning blade 51 includes a support body 52 and an elastic body 53, and is basically the same as the cleaning blade 51 in the image forming apparatus 10.

  The image forming apparatus 50 forms an image as follows. First, the developing unit B of the developing unit 20 visualizes the electrostatic latent image on the surface of the image carrier 11 as a developer image with the black developer 22B and transfers the image onto the intermediate transfer belt 7 (primary transfer). Subsequently, in a state where the pressure contact of the cleaning blade 51 to the intermediate transfer belt 7 is released, the image carrier 11 and the intermediate transfer belt 7 rotate once, and the developing units C, M, and Y respectively apply the intermediate transfer belt 7 to the intermediate transfer belt 7. The developer image is superimposed and transferred to form a color image. The color image reaches the secondary transfer unit 40 by the rotation of the intermediate transfer belt 7 and is transferred onto the recording medium 16 conveyed to the secondary transfer unit 40 (secondary transfer). Next, the recording medium 16 in which the color image is visualized is conveyed to the fixing unit 30 and the color image is fixed as a permanent image. On the other hand, when the developer image is transferred onto the recording medium 16, the cleaning blade 51 is pressed against the intermediate transfer belt 7, and the developer remaining on the surface of the intermediate transfer belt 7 that has passed through the secondary transfer unit 40 is It is removed by the cleaning blade 51 disposed downstream. In this way, a color image is formed on the recording medium 16. Although the case where a color image is formed using the image forming apparatus 50 has been described, in the case of forming a monochrome image, the developer image primarily transferred to the intermediate transfer belt 7 is immediately secondary transferred to the recording medium 16. Then, it may be conveyed to the fixing means 30.

  According to the image forming apparatuses 10 and 50, since the endless belt 1 is mounted as the intermediate transfer belt 7, the releasability of the developer at the time of primary transfer and at the time of secondary transfer is excellent, and the developer is desired. In addition, the image can be transferred from the image carrier 11 to the intermediate transfer belt 7 and from the intermediate transfer belt 7 to the recording body 16. Further, the initial pressure contact state between the intermediate transfer belt 7 and the cleaning blade 51 can be maintained for a long period of time. Therefore, according to these image forming apparatuses, a high-quality image can be formed.

  The image forming apparatuses 10 and 50 are electrophotographic image forming apparatuses. In the present invention, the image forming apparatuses 10 and 50 are not limited to the electrophotographic system. For example, electrostatic image forming is performed. It may be a device. The image forming apparatuses 1010 and 50 are image forming apparatuses such as copying machines, facsimile machines, and printers.

  The image forming apparatuses 10 and 50 include one cleaning blade 51. However, in the present invention, the image forming apparatus may include a plurality of cleaning blades.

Example 1
First, the endless belt base 2 was produced. In a reaction vessel, N-methyl-2-pyrrolidone, trimellitic anhydride, an equivalent amount of diphenylmethane-4,4′-diisocyanate, and reaction raw materials (trimellitic anhydride and diphenylmethane-4,4′- 2 mol% of potassium fluoride (catalyst) is added to the total number of moles of diisocyanate), and the temperature is raised from room temperature to 150 ° C. over 30 minutes with stirring. (Substantially fully ring-closed polyamideimide resin) A 20% by mass aromatic polyamideimide solution was obtained. N-methyl-2-pyrrolidone was further added to this solution to prepare a polyamideimide solution having a reactant concentration of 15% by mass. To the obtained polyamideimide solution, an oxidation-treated carbon black (trade name “Printex 150T”, manufactured by Degussa, pH 4.0, volatile content 10.0%) is added to a total of 100 masses of the polyamideimide resin and the oxidation-treated carbon black. The resin composition was prepared by adding 18% by mass with respect to% and mixing and dispersing in a pot mill for 24 hours. 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. Next, ring-shaped lids (inner diameter: 170 mm, outer diameter: 250 mm) are fitted into the openings at both ends of the mold, the mold is closed, and the resin composition is rotated at a speed of 1,000 rpm. 190 g was injected around the circumference. Next, the mold was rotated at the same speed for 30 minutes to uniformly spread the resin composition layer on the inner peripheral surface of the mold. Next, while rotating the mold at the same speed, the temperature around the mold was maintained at 80 ° C. with a hot air dryer, and this state was maintained for 30 minutes to form a film-shaped molded body. Thereafter, the rotation of the mold was stopped, the film-shaped molded body was taken out from the centrifugal molding machine together with the mold, subjected to superheated steam treatment in a superheated steam furnace adjusted to 250 ° C. for 2 hours, allowed to cool at room temperature, and endless. A belt molded body was obtained. The endless belt molded body was cooled together with the mold, the endless belt molded body was peeled off due to the difference in thermal expansion coefficient between the mold and the endless belt molded body, and the endless belt molded body was removed from the mold. Both end portions of the endless belt molded body were cut and cut into a size having a circumference of about 226 mm, a width of 240 mm, and a thickness of 100 μm to produce an endless belt base.

  A urethane solution having a solid content of 30% by mass (trade name “Nipporan 5120”, manufactured by Nippon Polyurethane Industry Co., Ltd.) was prepared. To this urethane solution, 1.2 parts by mass of hydrophobic silica (trade name “TS720”, manufactured by Cabot Corporation) is added with respect to 100 parts by mass of the urethane solution (4 parts by mass with respect to 100 parts by mass of the urethane adjusting component). The urethane composition was prepared by stirring at room temperature for 10 minutes. Subsequently, this urethane composition was uniformly applied to the outer peripheral surface of the endless belt base 2 by a doctor blade coating method. The application amount of the urethane composition was such that the thickness of the elastic layer 3 was 600 μm (in a non-dry state). The applied urethane composition was heated at 150 ° C. for 1 hour to form an elastic layer 3 having a thickness of 200 μm on the outer peripheral surface of the endless belt substrate 2. Thus, the endless belt of Example 1 was manufactured. The hydrophobic silica was spherical with an amorphous content of 10% by mass, and the average particle size by Coulter counter method was 6 μm.

(Example 2)
An endless belt of Example 2 was produced in the same manner as in Example 1 except that hydrophilic silica (trade name “AEROSIL200”, manufactured by Nippon Aerosil Co., Ltd.) was used instead of the hydrophobic silica. The hydrophilic silica was spherical with an amorphous content of 21% by mass, and the average particle size was 11 μm by the Coulter counter method.
(Examples 3 to 5)
1.2 parts by mass of the hydrophobic silica is 6 parts by mass (20 parts by mass with respect to 100 parts by mass of the urethane adjusting component) and 29 parts by mass (96.7 parts by mass with respect to 100 parts by mass of the urethane adjusting component). Part) and 2 parts by mass (6.7 parts by mass with respect to 100 parts by mass of the urethane adjusting component), the endless belts of Examples 3 to 5 were produced in the same manner as Example 1.

(Example 6)
An endless belt of Example 6 was produced in the same manner as in Example 1 except that a urethane solution (solid content 30%, trade name “LQ3510”, manufactured by Sanyo Chemical Co., Ltd.) was used instead of the urethane solution.
(Example 7)
In a urethane solution, fluororesin particles (chemical name “polytetrafluoroethylene particles”, trade name “Lublon L-2”, average particle size 0.2 μm, manufactured by Daikin Chemical Industries, Ltd.) are added to 100 parts by mass of the urethane solution. 10 parts by mass (33.3 parts by mass with respect to 100 parts by mass of the urethane-adjusting component) was added and stirred at room temperature for 10 minutes to prepare a urethane composition. An endless belt of Example 7 was produced in the same manner as in Example 1 except that this urethane composition was used.

(Comparative Example 1)
An endless belt of Comparative Example 1 was produced in the same manner as in Example 1 except that the hydrophobic silica was not used.
(Comparative Example 2)
An endless belt of Comparative Example 2 in the same manner as in Example 1 except that an alumina (aluminum oxide) filler (trade name “YFA-07070”, manufactured by Kinsei Matec Co., Ltd.) was used instead of the hydrophobic silica. Manufactured.
(Comparative Example 3)
An endless belt of Comparative Example 3 was produced in the same manner as in Example 7 except that the hydrophobic silica was not used.

(Comparative Example 4)
In the same manner as in Example 1 except that a silicone rubber composition (trade name “KE series”, manufactured by Shin-Etsu Chemical Co., Ltd., composition is shown below) was used instead of the urethane solution, Comparative Example 3 An endless belt was produced.
<Composition of silicone rubber composition>
・ 100 parts by mass of silicone raw rubber ・ 2.0 parts by mass of addition reaction crosslinking agent “C-153A” (manufactured by Shin-Etsu Chemical Co., Ltd .: trade name) ・ Blowing agent azobis-isobutyronitrile (trade name “KEP-13”, 3.0 parts by mass of Shin-Etsu Chemical Co., Ltd. ・ Appropriate amount of platinum catalyst as addition reaction catalyst, appropriate amount of reaction control agent, and “C-3” as organic peroxide cross-linking agent (manufactured by Shin-Etsu Chemical Co., Ltd .: Product name) proper amount

(Comparative Example 5)
An endless belt of Comparative Example 5 in the same manner as in Example 1 except that a resin composition containing 100 parts by mass of vinyl chloride-vinyl acetate copolymer resin and 100 parts by mass of silica was used instead of the urethane composition. Manufactured.

(Silica and fluororesin in urethane elastic layer)
When the urethane elastic layer of each endless belt was confirmed by gas chromatography, the content of silica and fluororesin relative to 100 parts by mass of urethane in the urethane elastic layer was included in each urethane composition forming the urethane elastic layer. The content was almost the same as the content of 100 parts by mass of the silica and fluororesin urethane adjustment component.

(Measurement of static friction coefficient)
The static friction coefficient of the elastic layer in each endless belt was measured five times according to the measurement method described above, and the arithmetic average value thereof was taken as the static friction coefficient of each endless belt. The results are shown in Table 1.

(Measurement of volume resistivity, surface resistivity, microhardness and JIS A hardness)
The volume resistivity, surface resistivity, ultra-fine hardness or JIS A hardness of each endless belt, its endless belt substrate and urethane elastic layer were measured by the above method, and the results are shown in Table 1.

(Developer releasability evaluation)
Each endless belt is mounted as an intermediate transfer belt 7 in the image forming apparatus trade name “DocuPrint C830” (manufactured by Fuji Xerox Co., Ltd.) shown in FIG. 2, and then 10 and 10 in an environment of a temperature of 22 ° C. and a relative humidity of 60%. 000 sheets were printed. Thereafter, each endless belt is removed, and on each endless belt, the surface of the elastic layer 3 located between the secondary transfer portion 40 and the cleaning blade 51 can be visually observed to confirm that the developer adheres to the surface. "◎" when there was no developer, "○" when the developer was adhered to the surface but there was no functional problem, "○", the developer was adhered to the surface so that a functional problem occurred The case is shown as “x” in Table 1.

(Pressure contact state test with cleaning blade)
The pressure contact state between each endless belt and the cleaning blade was evaluated in the same manner as in the static friction coefficient measurement method. That is, the endless belt was run for 5 hours in a state where the cleaning blade was pressed against the surface of the elastic layer of each endless belt, and it was evaluated whether the cleaning blade turned back in the running direction of the endless belt. As a result, when the endless belt is running, the cleaning blade does not turn over, and the pressure contact state between each endless belt and the cleaning blade is maintained while the endless belt is running. “○” indicates that the pressure contact state has changed slightly to the extent that there is no problem with the blade (no bounce), the cleaning blade bounces while the endless belt is running, and the desired function cannot be demonstrated. The case is shown as “x” in Table 1.

FIG. 1 is a schematic side view showing an endless belt which is an embodiment of an endless belt according to the present invention. FIG. 2 is a schematic view of a tandem type color image forming apparatus which is an example of the image forming apparatus according to the present invention. FIG. 3 is a schematic view of a multi-pass color image forming apparatus which is an example of the image forming apparatus according to the present invention. FIG. 4 is a view showing a cleaning blade which is an embodiment of a cleaning blade pressed against an endless belt according to the present invention, and FIG. 4A is a view of one of the cleaning blades pressed against the endless belt according to the present invention. FIG. 4B is a front view showing a cleaning blade as an embodiment, and FIG. 4B is a side view of the cleaning blade as an embodiment of the cleaning blade pressed against the endless belt according to the present invention.

Explanation of symbols

1 Endless belt 2 Endless belt base 3 Urethane elastic layer (elastic layer)
7 Endless belt (intermediate transfer belt)
10, 50 Image forming apparatus 11, 11B, 11C, 11M, 11Y Image carrier 12B, 12C, 12M, 12Y Charging means 13B, 13C, 13M, 13Y Exposure means 14, 14B, 14C, 14M, 14Y Transfer means 15B, 15C , 15M, 15Y Image carrier cleaning blade 16 Recording member 20, 20B, 20C, 20M, 20Y Developing means 21B, 21C, 21M, 21Y, 34 Housing 22B, 22C, 22M, 22Y Developers 23B, 23C, 23M, 23Y Developer carrier 30 Fixing device 31 Fixing roller 32 Pressure roller 33 Fixing belt support roller 35 Endless belt (fixing belt)
40 Secondary transfer section 42 Support roller 43 Tension roller 44 Opposing roller 45 Secondary transfer roller 46 Electrode rollers B, C, M, Y Developing unit 51 Cleaning blade 52 Support body 53 Elastic body 55 Plate-shaped section 56 Mounting section

Claims (4)

  An endless belt comprising: an endless belt base; and a urethane elastic layer formed on the endless belt base, wherein the urethane elastic layer contains silica.   The endless belt according to claim 1, wherein the urethane elastic layer contains a fluororesin.   The endless belt according to claim 1 or 2, wherein the urethane elastic layer has a static friction coefficient in a range of 0.7 to 1.7.   An image forming apparatus comprising: the endless belt according to claim 1; and a cleaning blade that presses against an outer surface of the endless belt.

Images