JP2011123180A - Multilayer elastic belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer elastic belt for an electrophotographic device with excellent flexibility required for an intermediate transfer belt, that is, with excellent bending durability represented by MIT fold number; having primary transfer characteristics, such as no deficiency in an image and clarity in thin line printing, and secondary transfer characteristics, such as good followability to the asperity paper; and furthermore, with excellent friction durability of a surface layer. <P>SOLUTION: The multilayer elastic belt for an electrophotographic device includes at least three layers of a surface layer including a mold-releasing material, an elastic layer including an elastic rubber material, and a base material layer including a high-strength resin material, in order from the surface side. Hysteresis loss calculated from the result of dynamic ultra-micro hardness measurement (ISO 14577-1) measured from the surface side is 20% or more. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a multilayer elastic belt used in an image forming apparatus using an electrophotographic method such as a digital printing machine, a copying machine, a printer, a facsimile machine or the like. Specifically, an intermediate transfer belt, a transfer conveyance belt, and a paper conveyance used for transferring a dry powder or wet liquid toner image on an electrostatic latent image formed on a photoreceptor to a recording material such as paper. The present invention relates to a multilayer elastic belt for an electrophotographic apparatus such as a belt.

  As intermediate transfer belts and transfer conveyance belts used in image forming apparatuses, polycarbonate resin (PC), polyvinylidene fluoride (PVdF), polyalkylene phthalate, PC / polyalkylene phthalate (PAT) blend material, ethylene-tetrafluoroethylene A semiconductive endless belt made of a thermoplastic resin such as a copolymer (ETFE) is generally used.

  In addition, an intermediate transfer belt has been proposed in which a polyimide resin having excellent mechanical characteristics and thermal characteristics is the main component and carbon black is dispersed as a conductive fine powder (see, for example, Patent Document 1). In recent years, a high-speed full-color image forming apparatus or the like often uses a tandem system in which a plurality of photoconductors are arranged, and a high elastic modulus material is used for the intermediate transfer belt to prevent color registration. In this respect, the polyimide resin is very excellent. However, high modulus polyimide resin is generally brittle and poor in flexibility, so when used as an intermediate transfer belt or transfer conveyance belt in an image forming apparatus, cracking occurs when the belt is attached. Or cracks caused by meandering while running. In addition, transfer failure may occur due to the loss of nip followability between the latent image carrier and the transfer roll.

  Various studies have been made on methods for solving the problems caused by the properties of these polyimide resins. For example, a polyimide resin having both high elastic modulus and flexibility by controlling the amount of residual solvent inside the belt. It has been reported that an endless belt can be obtained (for example, see Patent Document 2). However, the solvent remaining in the polyimide resin causes a decrease in resistance of the intermediate transfer belt during use. Furthermore, the essential flexibility was not sufficient.

  On the other hand, the present inventors have proposed a multi-layer intermediate transfer belt having an elastic layer in order to cope with high image quality of the transfer belt (see, for example, Patent Documents 3 and 4). Since the intermediate transfer belt provided with such an elastic layer is excellent in flexibility, it is possible to easily and stably form a transfer area with a photosensitive member that contacts the intermediate transfer belt during primary transfer, and at the same time, between the photosensitive member and the like. This reduces the compressive stress applied to the toner, and is useful for measures against defects in the image and for improving the sharpness of fine line printing. In addition, the intermediate transfer belt that does not have elasticity has a problem in that when a recording medium with large surface irregularities is used, there is a problem that an image is lost in a concave portion during secondary transfer. The intermediate transfer belt is very effective in improving such problems.

  Further, such an intermediate transfer belt compatible with high image quality imparts rubber elasticity in the thickness direction of the belt, while toner releasability necessary for the transfer belt is also required as an important factor. That is, when transferring toner from the surface of the intermediate transfer belt to a medium such as paper, releasability with respect to the toner is required. Therefore, it is not preferable that the rubber elastic layer having adhesiveness to the toner is exposed on the surface of the intermediate transfer belt. Therefore, a resin surface layer having a low friction coefficient and excellent toner releasability is usually provided on the rubber elastic layer (see, for example, FIG. 1). It is known that it is effective to make the thickness of the surface layer as thin as possible in order to obtain a high-quality image, and various intermediate transfer belts with a thin surface layer have been studied.

  However, since the intermediate transfer belt for an image forming apparatus receives external force from a sliding member that contacts the belt surface such as paper, a cleaning blade, or a roll, when the surface layer is a thin film, the stress applied to the belt is reduced. There was a problem that the surface layer was worn out and concentrated, and cracking or peeling occurred. Further, when the hardness of the entire belt is increased in order to solve this problem, there is a problem that although the wear durability is excellent, the effect of improving the transfer efficiency due to the softness becomes insufficient and the image quality is lowered.

  As described above, it is very difficult to make an intermediate transfer belt having a thin surface layer with excellent durability against external friction while maintaining a high-quality image.

Japanese Patent No. 3116143 Japanese Patent No. 4241543 JP 2007-240939 A JP 2009-015006 A

  The present invention is excellent in flexibility required for an intermediate transfer belt, that is, bending durability typified by MIT durability, primary transfer characteristics with clear image printing and fine line printing, and paper unevenness followability. An object of the present invention is to provide a multilayer elastic belt for an electrophotographic apparatus that has good secondary transfer characteristics and is excellent in friction durability of a surface layer.

  As a result of intensive studies to solve the above problems, the present inventors have improved the bending durability of the belt and the surface friction durability in terms of durability against external pressure. I found that the same solution can be used. In other words, the bending durability of the belt depends on how much the elastic layer covering the base layer made of a high-strength resin material such as polyimide, which has a high brittleness, is to follow, The friction durability depends on how much the rubber under the surface deforms following the surface layer when the surface layer is pressed against a cleaning blade or the like. Therefore, it is possible to improve both the durability of the belt and the friction durability of the surface by adopting rubber with physical properties that disperse stress applied to the movement of the base layer and surface layer in the elastic layer. The headline and the present invention were completed.

That is, the present invention provides the following elastic belt.
Item 1. In order from the surface side, a multilayer elastic belt for an electrophotographic apparatus comprising at least three layers of a surface layer containing a releasable material, an elastic layer containing an elastic rubber material, and a base material layer containing a high-strength resin material,
A multilayer elastic belt for an electrophotographic apparatus having a hysteresis loss of 20% or more calculated from the result of dynamic microhardness measurement (ISO 14577-1) measured from the surface side.
Item 2. 2. The multilayer elastic belt for an electrophotographic apparatus according to item 1, wherein the surface layer has a Young's modulus of 2,000 MPa or less and the surface layer has a thickness of 5 μm or less.
Item 3. Item 3. The multilayer elastic belt for an electrophotographic apparatus according to Item 1 or 2, wherein the releasable material is fluororesin and / or fluororubber.
Item 4. Item 4. The multilayer elastic belt for an electrophotographic apparatus according to any one of Items 1 to 3, wherein the material constituting the elastic layer has a type A hardness of 20 ° or more.
Item 5. The multilayer elastic belt for an electrophotographic apparatus according to any one of Items 1 to 4, wherein the elastic rubber material is a polyurethane elastomer material, and a hysteresis loss of a cured product of the polyurethane elastomer material alone is 20% or more.
Item 6. Item 6. The item according to any one of Items 1 to 5, wherein the high-strength resin material is at least one material selected from the group consisting of polyimide, polyamideimide, polycarbonate, PVdF, polyamide, and ethylene-tetrafluoroethylene copolymer. Multilayer elastic belt for electrophotographic devices.

  In the multilayer elastic belt of the present invention, an elastic layer that is less repulsive to external force is provided as an intermediate layer, so that the elastic layer follows the movement of adjacent layers without rebounding. It is possible to avoid stress concentration on the surface layer that is easily worn, and to simultaneously improve the bending durability of the belt and the friction durability of the surface. Specifically, by setting the hysteresis loss measured from the surface side of the multilayer elastic belt to 20% or more, the flexibility required for the intermediate transfer belt, that is, the bending durability represented by the MIT durability, is excellent. Providing a multilayer elastic belt that has primary transfer characteristics with clear image printing and fine line printing, secondary transfer characteristics with good irregularity on paper, and excellent surface layer friction durability. can do.

It is a cross-sectional schematic diagram of the three-layer elastic belt of this invention. It is a hysteresis loss measuring method from the belt surface in an Example. It is a schematic diagram of the apparatus used for film forming of each layer in an Example.

  Hereinafter, the present invention will be described in detail.

1. Formation of Surface Layer The surface layer in the multilayer elastic belt of the present invention is a layer for directly placing toner and transferring and releasing the superimposed four color toners onto paper.

  The surface layer is preferably formed from a composition for forming a surface layer containing a releasable material from the viewpoint of facilitating release of the toner, and examples of the releasable material include fluororesin or fluororubber.

  Examples of the fluororesin include polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer (THV), and polyvinylidene. Fluoride (PVdF), vinylidene fluoride (VdF) -hexafluoropropylene (HFP) copolymer (VdF-HFP copolymer), or a mixture thereof may be mentioned. In addition, as for the ratio of HFP of a VdF-HFP copolymer, about 1-15 mol% is preferable.

  Examples of the fluororubber include vinylidene fluoride rubber (FKM), tetrafluoroethylene-propylene rubber (FEPM), tetrafluoroethylene-purple fluorovinyl ether rubber (FFKM), and the like. Among these, FKM has many types and is preferable from the viewpoint of availability.

  When the surface layer is formed of the fluororesin alone, it tends to be difficult to adhere to the rubber constituting the elastic layer. Therefore, when the surface layer is formed of a fluororesin alone, it is preferable to treat the surface to be bonded to the elastic layer before bonding to the elastic layer.

  Although it does not specifically limit as a surface treatment method, For example, the physical surface treatment by a chemical surface treatment by a metal sodium solution etc., plasma, a corona discharge, etc. can be mentioned.

  Among the fluororesins, tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer (THV), polyvinylidene fluoride (PVdF), vinylidene fluoride (VdF) -hexafluoropropylene (HFP) copolymer (VdF). -HFP copolymer), or a mixture thereof, can relatively increase the surface energy of the surface to be bonded, and can be easily bonded to the rubber constituting the elastic layer. it can. In that case, adhesion may be improved by using a primer.

  Further, in other fluororesins such as polytetrafluoroethylene (PTFE), it is preferable to use a binder. Specifically, for example, a method of forming the surface layer using a fluororesin previously dispersed in a binder such as a urethane resin or an acrylic resin can be used.

  You may add the fine powder of polytetrafluoroethylene (PTFE) to the material of fluororesin or fluororubber. In this case, the PTFE fine powder may be directly dispersed in the raw material solution, or may be added to the raw material solution using a PTFE fine powder dispersion previously diluted with a solvent or the like.

  The addition amount of the PTFE fine particle powder is preferably about 20% by weight or less, more preferably about 10% by weight or less based on the weight of the fluorine-based raw material of the surface layer forming composition.

  Further, a layered clay mineral may be added to the surface layer, and examples of the layered clay mineral include smectite and hydrotalcite.

  These layered clay minerals may be natural products or synthetic products. For example, as synthetic montmorillonite, Kunipia F manufactured by Kunimine Kogyo Co., Ltd .; as synthetic hectorite, Laporte XLG, Laponite RD of Laporte, Lucentite STN manufactured by Corp Chemical Co., etc .; Smecton SA, etc. manufactured by Co., Ltd. can be mentioned, and these can be obtained commercially.

  The said layered clay mineral can be used individually by 1 type or in combination of 2 or more types.

  The blending ratio of the layered clay mineral is preferably 0.1 to 5% by weight, more preferably 0.5 to 3% by weight, based on the total weight of the surface layer. By blending the layered clay mineral at such a ratio, even if the surface layer of the transfer belt is made thin, excellent rough paper transfer performance and durability can be realized with little generation of pinholes.

  Here, the excellent rough paper transfer performance means that white paper with severe unevenness such as bond paper is printed with solid cyan, and the whiteness of toner in the deepest part (concave part) is visually determined. It means that there is no omission and transfer is performed without unevenness.

The volume resistivity of the surface layer is usually preferably 10 ¹² Ω · cm or more, more preferably 10 ¹² to 10 ¹⁵ Ω · cm.

  Here, the volume resistivity of the surface layer refers to a surface having a thickness of about 10 μm that is produced using the surface layer forming composition for forming the surface layer under the same conditions as those for the surface layer in the multilayer elastic belt of the present invention. It is the value measured using the layer.

  In addition, it is possible to control the semiconductivity by adding a conductive agent such as carbon black, but since the effect is limited and uniform dispersion is difficult, the surface layer does not contain a conductive agent. May be. Since the surface layer is not affected by the change in the environment (temperature, humidity, etc.), stable primary and secondary transfer of the toner is possible, and high image quality can be realized.

  The thickness of the surface layer is preferably 5 μm or less, and more preferably 1 to 3 μm. If the thickness is too large, the rubber elasticity of the elastic layer is impaired, which is not preferable. If the thickness is too thin, there is a tendency that a problem occurs in durability such that a hole is easily formed in the surface layer.

  The Young's modulus of the surface layer is preferably 2,000 MPa or less, and more preferably 1,200 MPa or less. It is preferable for the Young's modulus to be 2,000 MPa or less because it is possible to prevent the toner from dropping out during thin line printing due to stress concentration on the toner. On the other hand, if the Young's modulus exceeds 2,000 MPa, even if the hardness of the rubber constituting the intermediate layer that is the base of the surface layer is softened, the stress concentration of the toner cannot be avoided due to the rigidity of the surface layer, and the thin line is lost. There is a tendency to occur. On the other hand, the lower limit of the Young's modulus of the surface layer is not particularly limited. However, if the Young's modulus is extremely low, the friction coefficient of the surface layer increases if the rubber hardness of the underlying intermediate layer is softened. The transfer efficiency may be deteriorated. In such a case, it is preferable to set the Young's modulus to 300 MPa or more because an increase in the friction coefficient of the surface layer can be suppressed and deterioration of the secondary transfer efficiency can be prevented.

  Here, the Young's modulus of the surface layer refers to a surface layer having a thickness of about 10 μm produced under the same conditions as the surface layer production conditions in the multilayer elastic belt of the present invention using the surface layer forming composition for forming the surface layer. It is the value measured using.

  The film formation of the surface layer will be described below by taking as an example the case of centrifugal molding of a fluororesin.

  First, the weight of the fluororesin or the like is adjusted so that the finished surface layer has a target thickness of 1 to 5 μm. A composition for forming a surface layer obtained by dissolving or swelling a weighed fluororesin and optionally added layered clay mineral in a solvent is cast on the inner surface of a cylindrical mold and centrifugally molded.

  Solvents used include water; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ester solvents such as ethyl acetate and butyl acetate; amide solvents such as N, N-dimethylformamide and N, N-dimethylacetamide; Alternatively, a mixed solvent thereof or the like can be given.

  The solid content concentration of the composition for forming a surface layer may be about 1 to 30% by weight.

  Centrifugal molding of the surface layer can be performed as follows using, for example, a cylindrical mold.

  After injecting the surface layer forming composition in an amount equivalent to obtaining the final thickness into the stopped cylindrical mold, gradually increase the rotation speed to the speed at which centrifugal force works, The composition is uniformly cast on the entire inner surface of the mold by centrifugal force.

  The inner surface of the cylindrical mold has a mirror surface, specifically, the surface roughness (JIS B0601-1994 ten-point average roughness) is 1 μmRz or less, and the inner surface of the mold is on the outer surface of the surface layer of the endless multilayer elastic belt. Transcribed. In addition, the inner surface of the mold can be blasted for the purpose of adjusting the belt surface layer to have desired irregularities.

  Further, a release agent is applied to the inner surface of the cylindrical mold so that the film (surface layer) after curing of the surface layer forming composition can be released from the inner surface of the mold cleanly. As the release agent, a fluorine release agent, a silicone release agent, a semi-permanent release agent, or the like is used.

  The cylindrical mold is placed on a rotating roller, and indirectly rotated by the rotation of the roller. The size of the mold can be appropriately selected according to the desired size of the surface layer, that is, the outer diameter of the multilayer elastic belt.

  For the heating, a heat source such as a far-infrared heater is disposed around the mold, and indirect heating from the outside is performed. Usually, the temperature may be gradually raised from room temperature to about 120 to 200 ° C. and heated at the temperature after the temperature rise for about 0.5 to 2 hours. Thereby, the composition for forming a surface layer injected into the inner surface of the cylindrical mold is cured, and a seamless (seamless) tubular surface layer can be formed on the inner surface of the cylindrical mold.

2. Formation of Elastic Layer The rubber elastic layer can be formed of an elastic layer forming composition containing an elastic rubber material.

  Specific examples of the elastic rubber material include a cured product such as liquid urethane rubber, and examples of the liquid urethane rubber include thermosetting polyurethane elastomers.

  This liquid urethane rubber can be generally obtained by a polyaddition reaction of a polyol and a diisocyanate.

  It is important that the elastic layer in the multilayer elastic belt of the present invention is a layer that does not exhibit a large resilience to external force so that the hysteresis loss measured from the surface side of the multilayer elastic belt is 20% or more. .

  By making the elastic layer a layer that does not exhibit a large resilience to external force, the elastic layer can follow the movement of the adjacent base layer or surface layer without repelling, so that the base layer that is easy to break It is possible to avoid stress concentration on the surface layer that is easily worn, and to simultaneously improve the bending durability of the belt and the friction durability of the surface.

  Examples of the method for making the elastic layer a layer that does not exhibit a large repulsion to external force include a method for controlling the hysteresis of the elastic rubber material constituting the elastic layer. Specifically, the hysteresis loss of the elastic rubber material constituting the elastic layer is preferably 20% or more, more preferably 25% or more, and further preferably 30% or more. By setting the hysteresis loss of the elastic rubber material in the above range, the hysteresis loss measured from the surface side of the multilayer elastic belt can be surely made 20% or more. The upper limit of hysteresis loss of the elastic rubber material is not particularly specified. However, when it exceeds 70%, it is difficult to obtain rubber elasticity, and there is a tendency for creep property and compression set to increase. It may affect functions such as resist properties. Therefore, the hysteresis loss of the elastic rubber material is preferably 70% or less.

  Further, the hysteresis loss of the elastic rubber material in the present invention is measured according to JIS K7312, and the test may be performed by either the tension method or the compression method.

  Examples of the method for controlling the hysteresis of the rubber material include the following methods.

(1) Method for reducing the average molecular weight of the polyol forming the liquid urethane rubber Hysteresis loss increases by using a polyol having a low average molecular weight.
The average molecular weight of the polyol is preferably about 500 to 5,000 in terms of weight average molecular weight, and more preferably about 500 to 3,500.
Examples of such liquid urethane rubber include Exenol manufactured by Asahi Glass Co., Ltd.

(2) Method for controlling crosslink density, which is a chemical bond between polymer chains Hysteresis loss can be increased by reducing the crosslink density. Specific methods for controlling the crosslink density include a method based on material design, a method using a curing agent with few functional groups, a method for changing the processing temperature during curing, a method for controlling the amount of the curing agent, and the like. These methods can be employed singly or in combination.

(Method by material design)
Specifically, the material design method is an elastic rubber material (liquid urethane rubber) by designing the elastic rubber material (liquid urethane rubber) so that the number of isocyanate groups that become reactive sites during crosslinking is reduced. ) Crosslink density can be reduced.

  As described above, the liquid urethane rubber can be obtained by a polyaddition reaction of a polyol and a diisocyanate. The mixing ratio of the raw material polyol and diisocyanate is such that the NCO group of the diisocyanate is about 1 to 1.2 equivalents per 1 equivalent of active hydrogen of the polyol, but the standard design is 0. Hysteresis loss can be increased by setting it to about 8 to 1 equivalent (preferably about 0.8 to 0.98 equivalent). If the NCO group is less than 0.8 equivalent, rubber physical properties such as compression set and creep are deteriorated, which is not suitable depending on the use conditions of the transfer belt or the like.

(Method using a curing agent with few functional groups)
Since a crosslinking density can be lowered by selecting a curing agent having a small number of functional groups, hysteresis loss can be increased.

  As a functional group number of a hardening | curing agent, it is preferable that it is 2-4 in 1 molecule, for example, and it is more preferable that it is 2-3.

  Curing agents with few functional groups include polyhydric alcohol curing agents such as glycerin, trimethylolethane, trimethylolpropane, hexanetriol, triethanolamine; diphenylmethanediamine, m-phenylenediamine, alkanolamines (ethanolamine, diethanolamine) Etc.) and the like. Of these, amine-based curing agents are preferred.

  Specifically, Duranate from Asahi Kasei Chemicals, Takelac from Mitsui Chemicals Polyurethane, Pandex E and CLH from DIC, Millionate and Coronate from Nippon Polyurethane Industry Can be mentioned.

(Method of changing the processing temperature during curing)
By reducing the curing temperature of the liquid urethane rubber, the crosslinking density can be lowered, and as a result, the hysteresis loss of the elastic rubber material increases.

  As curing temperature, 80-140 degreeC is preferable and it is more preferable that it is 80-135 degreeC.

(Method for controlling the amount of curing agent)
By reducing the blending amount of the liquid urethane rubber curing agent, the crosslinking density can be lowered, and as a result, the hysteresis loss of the elastic rubber material is increased.

  As the addition amount of the curing agent, the active group (for example, NCO group) of the curing agent is preferably about 0.8 to 1.0 equivalent with respect to 1 equivalent of active hydrogen of the liquid urethane rubber, and 0.8 to 0 About 98 equivalents are more preferable.

  In the present invention, by employing at least one of the above methods, the hysteresis loss of the elastic rubber material constituting the elastic layer can be 20% or more. By using an elastic rubber material having a hysteresis loss of 20% or more, it is possible to obtain an elastic layer that does not exhibit a large repulsion with respect to an external force. As a result, the hysteresis loss measured from the surface side in a multilayer elastic belt is reduced. It can surely be 20% or more.

  As the hardness of the elastic rubber material (liquid urethane rubber), it is preferable that the type A hardness (JIS K6253) of the cured product is 20 to 70 °, and more preferably 35 to 55 °. When the hardness is less than 20 °, the hysteresis loss can be increased, but the compression set and the tensile strength are deteriorated, which may be unsuitable for applications such as a transfer belt.

  The liquid urethane rubber may be either a polyester urethane rubber (AU) having an ester bond in the main chain or a polyether urethane rubber (EU) having an ether bond in the main chain. Specific examples include Pandex and Urehyper manufactured by DIC Corporation, Takenate manufactured by Mitsui Chemicals Polyurethane Corporation, and the like.

  Especially when using a thermosetting polyurethane elastomer, the main component is a liquid blocked urethane prepolymer formed by blocking the terminal isocyanate group with a blocking agent. Curing can be suppressed, which is preferable for processing.

Usually, some types of liquid urethane rubber have a volume resistivity of about 10 ⁹ to 10 ¹¹ Ω · cm without resistance adjustment, and are required to be electroconductive belts for electrophotography. Sex is obtained. However, the inherent ionic conductivity of rubber is often highly dependent on the temperature and humidity environment, and the ionic conductivity often varies greatly as the temperature and humidity environment changes greatly.

Because of these problems, the resistance is adjusted by adding a conductive agent whose electrical characteristics are less dependent on environmental fluctuations to urethane rubber whose volume resistivity is not less than 10 ¹³ Ω · cm. Are preferably used.

  Examples of the conductive agent whose electrical characteristics are less dependent on environmental fluctuation include carbon black and lithium ion salt.

  Examples of the carbon black include conductive carbon black such as acetylene black and ketjen black.

  The compounding amount of carbon black is preferably 5 to 40 parts by weight, more preferably 10 to 30 parts by weight, and still more preferably 10 to 25 parts by weight with respect to 100 parts by weight of the elastic rubber material (liquid urethane rubber).

In this way, by adding carbon black to urethane rubber, the elastic layer is given a semiconductivity of about 10 ⁷ to 10 ¹³ Ω · cm (preferably about 10 ⁹ to 10 ¹² Ω · cm). This is preferable because accurate semiconductivity suitable for the purpose can be obtained for various resistance value requirements. Further, since the obtained belt is electronically conductive by carbon black, it exhibits stable semiconductivity that is hardly affected by the external environment such as temperature and humidity.

Examples of ionic conductive agents using lithium ion salts include lithium bisimide (CF ₃ SO ₂ ) ₂ NLi and lithium trismethide (CF ₃ SO ₂ ) ₃ CLi. Specific examples include Sanconol manufactured by Sanko Chemical Industry Co., Ltd.

  In general, ion conductive agents that are often used are considered to exhibit electrical conductivity due to moisture absorption, which causes the environmental dependence of ionic conductivity. However, ionic conductive materials using lithium ion salts are thought to exhibit electrical conductivity by the movement of lithium ions due to the molecular movement of oxygen, and are less dependent on the environment. However, it is preferably used.

  When the ionic conductive agent is added, the amount added is preferably about 3.0 parts by weight or less with respect to 100 parts by weight of the elastic rubber material (liquid urethane rubber). Moreover, although a lower limit is not specifically limited, It is preferable that it is 0.1 weight part or more.

  The elastic layer forming composition containing the elastic rubber material (liquid urethane) whose resistance is adjusted by any of the methods in this manner is put on the inner surface of the surface layer formed on the inner side of the mold and is centrifugally molded. When the viscosity of the elastic layer forming composition is too high during centrifugal molding, it may be appropriately diluted with an ester solvent such as ethyl acetate or butyl acetate, or a solvent such as toluene or xylene.

  As the centrifugal molding method, for example, the same one as the above-mentioned surface layer molding equipment can be used.

  The molding temperature is gradually heated from room temperature, raised to about 110 to 160 ° C., which is a temperature range below the heat resistance limit of urethane rubber, and maintained in this state for about 0.5 to 3 hours to complete the curing.

  For the purpose of improving adhesion between the surface layer and the elastic layer, a method of applying a primer on the surface layer side by spraying, a method of adding a silane coupling agent to the liquid urethane material, a method of performing both, etc. You may take it.

The volume resistivity of the elastic layer is usually about 10 ⁷ to 10 ¹³ Ω · cm, preferably about 10 ⁹ to 10 ¹² Ω · cm, from the viewpoint of transferring toner as a belt by electrical control.

  The thickness of the elastic layer is usually 50 to 400 μm, preferably 120 to 300 μm, in consideration of the flexibility of the belt surface and prevention of image displacement during use.

3. Formation of Base Material Layer The base material layer in the multilayer elastic belt of the present invention is a layer for preventing the belt from being deformed by a stress applied to the belt during driving. Therefore, the mechanical property strength is required for the base material layer.

  The base material layer is preferably made of a composition for forming a base material layer containing a high-strength resin material from the viewpoint of mechanical physical strength. Examples of the high-strength resin material include polyimide and polyamideimide. Moreover, polycarbonate, PVdF, polyamide, an ethylene-tetrafluoroethylene copolymer, etc. can also be used as resin which forms a base material layer.

  Polyimide is usually produced by condensation polymerization of tetracarboxylic dianhydride and diamine or diisocyanate as monomer components by a known method.

  Examples of tetracarboxylic dianhydrides include pyromellitic acid, naphthalene-1,4,5,8-tetracarboxylic acid, naphthalene-2,3,6,7-tetracarboxylic acid, 2,3,5,6-biphenyl. Tetracarboxylic acid, 2,2 ', 3,3'-biphenyltetracarboxylic acid, 3,3', 4,4'-biphenyltetracarboxylic acid, 3,3 ', 4,4'-diphenyl ether tetracarboxylic acid, 3 , 3 ′, 4,4′-benzophenonetetracarboxylic acid, 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic acid, azobenzene-3,3 ′, 4,4′-tetracarboxylic acid, bis (2, 3-dicarboxyphenyl) methane, bis (3,4-dicarboxyphenyl) methane, β, β-bis (3,4-dicarboxyphenyl) propane, β, β-bis (3,4-dical) Kishifeniru) dianhydride such as hexafluoropropane, and the like.

  Examples of the diamine include m-phenylenediamine, p-phenylenediamine, 2,4-diaminotoluene, 2,6-diaminotoluene, 2,4-diaminochlorobenzene, m-xylylenediamine, p-xylylenediamine, 1,4 -Diaminonaphthalene, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, 2,4'-diaminobiphenyl, benzidine, 3,3'-dimethylbenzidine, 3,3'-dimethoxybenzidine, 3,4'-diamino Diphenyl ether, 4,4'-diaminodiphenyl ether (ODA), 4,4'-diaminodiphenyl sulfide, 3,3'-diaminobenzophenone, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminoazobenzene, 4,4 '-Diaminodiphenylmethane, β, β-bis (4-aminophen Nyl) propane and the like.

  Examples of the diisocyanate include compounds in which the amino group in the diamine component described above is substituted with an isocyanate group.

  Polyamideimide is produced by condensation polymerization of trimellitic acid and diamine or diisocyanate by a known method. In this case, examples of the diamine or diisocyanate include the same materials as those for the above polyimide.

  The thickness of the base material layer is usually 30 to 120 μm and preferably 50 to 100 μm in consideration of stress and flexibility applied to the belt during driving.

  The base material layer may contain a conductive agent as necessary.

  As the conductive agent, carbon black mentioned in the elastic layer can be used.

  When the conductive material is included in the base material layer, the amount used is usually about 5 to 30 parts by weight with respect to 100 parts by weight of the resin forming the base material layer. As a result, the base material layer can have a resistivity suitable for the intermediate transfer belt.

The volume resistivity of the base layer, from the viewpoint of performing transfer by electrical control of the toner as a belt substrate, usually preferably ¹⁰ 4 ^{to 10} about ^{12.5 Ω · cm, 10 9 ~10} 12.5 Ω · About cm is more preferable.

  The film forming method of the base material layer in the multilayer elastic belt of the present invention will be described below by taking as an example the case where polyimide is used as the resin for forming the base material layer.

  Tetracarboxylic dianhydride, which is the raw material of the polyimide, and diamine are reacted in a solvent to obtain a polyamic acid solution once. The solid content concentration of the polyamic acid solution may be about 10 to 40% by weight.

  Examples of the solvent include N-methyl-2-pyrrolidone (hereinafter referred to as “NMP”), N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, and hexamethyl. An aprotic organic polar solvent such as phosphoamide or 1,3-dimethyl-2-imidazolidinone is used. One or two or more of these solvents may be used. In particular, NMP is preferable.

  In order to impart desired semiconductivity to the base material layer, a conductive agent such as about 5 to 30 parts by weight of carbon black or the like is added to 100 parts by weight of the resin that forms the base material layer as necessary as described above. It may be added to the acid solution. In this case, the carbon black is uniformly dispersed by a ball mill. Thereby, the composition for base material layer formation containing a polyamic acid and a electrically conductive agent as needed is obtained.

  The obtained composition for forming a base material layer is subjected to centrifugal molding using a cylindrical mold or the like in the same manner as the surface layer / elastic layer. However, the inner surface of the mold in this case may be mirror-finished, but may have irregularities such as blasting as a method for increasing the adhesion area with the elastic layer made of a rubber material.

  In the heating, the inner surface of the mold is gradually heated to reach about 100 to 190 ° C., preferably about 110 to 130 ° C. (first heating stage). The temperature increase rate may be about 1 to 2 ° C./min, for example. The belt is maintained at the above temperature for 20 minutes to 3 hours, and approximately half or more of the solvent is volatilized to form a self-supporting belt.

  Next, as the second stage heating, treatment is performed at a temperature of about 280 to 400 ° C. (preferably about 300 to 380 ° C.) to complete imidization. Also in this case, it is preferable not to reach this temperature from the first stage heating temperature all at once, but to gradually increase the temperature to reach that temperature. The second stage heating may be performed with the endless belt attached to the inner surface of the cylindrical mold, or after the first heating stage, the endless belt is peeled off from the mold and taken out for further imidization. You may use for the heating means of and may heat at 280-400 degreeC. The time required for this imidization is usually about 20 minutes to 3 hours.

  As described above, the base material layer formed by centrifugal molding has a different inner diameter from the cylindrical mold used for forming the surface layer and the elastic layer from the viewpoint of the shrinkage rate of the raw material and the heat resistance temperature. It is preferable to use a base layer-dedicated mold.

  Similarly, when polyamideimide is used as the resin for forming the base material layer, diamine or diisocyanate derived from diamine and trimellitic acid are reacted in a solvent directly to form polyamideimide, and this is centrifuged. Thus, a seamless (seamless) polyamideimide substrate layer can be formed. Also in the case of using polyamideimide, a conductive agent such as carbon black can be added as necessary, and the addition amount is the same as in the case of the polyimide described above.

  Thus, the Young's modulus of the base material layer obtained by centrifugal molding is preferably 2,500 MPa or more, and more preferably 3,500 MPa or more. Moreover, although an upper limit is not specifically limited, It is preferable that it is about 8,000 MPa or less.

  When polycarbonate, PVdF, polyamide, ethylene-tetrafluoroethylene copolymer or the like is used as the material for the base material layer, a seamless base material layer can be formed by melting and extruding these resins. Also in this case, a conductive agent such as carbon black can be added as necessary, and the amount added is the same as in the case of the polyimide described above.

  When obtaining a seamless belt by extrusion molding as described above, it is preferable to select a material having a Young's modulus of 1,000 MPa or more, preferably 1,500 MPa or more in order to maintain the performance as a substrate.

  As described above, a base material layer having a seamless high strength can be obtained.

4). Formation of multilayer elastic belt (three layers)
A layer formed separately in the above-mentioned “2” and “3”, that is, a first belt composed of two layers of an integrated surface layer and an elastic layer, and a second belt composed of a base material layer The first belt is overlapped so that the inner surface (surface on the elastic layer side) of the first belt and the outer surface of the second belt are in contact with each other.

  You may apply | coat an adhesive agent and a primer between both as needed.

  After the superposition of both, it is preferable that the space between the two is sealed. Thereafter, the laminate is heat-treated to obtain an endless three-layer elastic belt in which the inner surface of the elastic layer and the outer surface of the base material layer are bonded.

  Details of the three-layer process will be described with specific examples.

  Laminate adhesive is uniformly applied to the inner surface (surface on the elastic layer side) of the two-layer film (first belt) made of the surface layer and the elastic layer formed in a state regulated by the inner surface of the cylindrical mold, and air-dried. .

  After applying a primer to the outer surface of the base material layer formed by another dedicated cylindrical mold and air-drying it, the inner layer is superposed on the inner surface of the elastic layer and closely contacts the inner surface of the base material layer so that the position does not shift. Insert a type.

  Thereafter, heat treatment is performed at about 100 ° C. for about 20 to 60 minutes, and interlayer adhesion is completed simultaneously with curing of the adhesive. If necessary, the three-layer belt after demolding may be further annealed at about 120 ° C. for about 3 to 5 hours. Thus, the multilayer elastic belt of the present invention is obtained.

  Examples of the laminating adhesive include Takelac A-969 manufactured by Mitsui Chemicals Polyurethane Co., Ltd. and Tyforce NT-810 manufactured by DIC Corporation. In addition, although use of said primer is arbitrary, it is preferable to use from the point of an adhesive strength improvement. Examples of the primer include DY39-067 manufactured by Toray Dow Corning Co., Ltd.

  In the above example, only the multilayer elastic belt of the present invention consisting of three layers has been described. However, in the present invention, layers other than the base material layer, the elastic layer, and the surface layer can be included. Two or more base layers, elastic layers, and surface layers can be provided.

  The multilayer elastic belt of the present invention completed as described above has a hysteresis loss of 20% or more measured from the surface side. Thus, the hysteresis loss as the belt completed body can be controlled by selecting the surface layer material and the elastic layer material. The upper limit of hysteresis loss is not particularly limited, but is preferably 50% or less.

  A method for measuring hysteresis loss will be described below.

  The hysteresis loss measured from the belt surface side is the same as the hysteresis loss of the elastic rubber material alone, and when the belt complete body is stressed and deformed to return to its original state, the ratio of plastic deformation to the total deformation is calculated. Find it. The specific method is as described in the examples.

  As described above, the multilayer elastic belt of the present invention is excellent in flexibility as an intermediate transfer belt, that is, bending durability represented by the number of MIT durability, by setting the hysteresis loss measured from the surface side to 20% or more. The belt has a primary transfer characteristic with clear thin line prints without voids, a secondary transfer characteristic with good irregularity followability to paper, and the like, and has excellent surface layer friction durability.

  The multilayer elastic belt of the present invention can be suitably used as an electrophotographic belt such as a transfer conveyance belt, a paper conveyance belt, or a transfer fixing belt, or an intermediate transfer belt used in an image forming apparatus.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example with a comparative example, this invention is not limited to these Examples.

  The following evaluation described in this specification was performed as follows.

<Concentration of solid content of composition for base material layer formation>
The sample is precisely weighed in a heat-resistant container such as a metal cup, and the weight of the sample at this time is Ag. The heat-resistant container containing the sample is placed in an electric oven and heated and dried while sequentially heating at 120 ° C. × 12 minutes, 180 ° C. × 12 minutes, 260 ° C. × 30 minutes, and 300 ° C. × 30 minutes. The weight of the solid content (solid content weight) is defined as Bg. The values of A and B of five samples of the same sample were measured (n = 5) and applied to the following formula (I) to determine the solid content concentration. The average value of the five samples was adopted as the solid content concentration.

<Solid Concentration of Surface Layer Forming Composition and Elastic Layer Forming Composition>
The raw materials are precisely weighed, and the weight of the solid or liquid raw material at this time is Cg. In order to dissolve the raw material in the solvent on the electronic balance, the solvent is gradually added while stirring, and the final solution weight is set to Dg. The solid content concentration is represented by the following formula (II).

<Thickness>
The thickness was measured as a mean value by measuring a total of 24 points of 3 points in the width direction and 8 points in the circumferential direction using a flat type probe of a contact-type film thickness measuring instrument.

<Young's modulus>
The Young's modulus was measured using Autograph AG-X manufactured by Shimadzu Corporation in accordance with JIS K7127.

Sample piece: strip shape of 25 × 250 mm Tensile speed: 20 mm / min

<Surface resistivity, volume resistivity>
Surface resistivity (Ω / □) and volume resistivity (Ω · cm) are measured at 23 ° C and 55% RH using a resistance measuring instrument “HIRESTA UP / UR Blob” manufactured by Mitsubishi Chemical Corporation. It was measured. A belt cut to a length of 360 mm in the width direction is used as a sample, and the surface resistivity is applied after 10 seconds at an applied voltage of 100 V at a total of 12 locations in the sample in the width direction, 3 locations at equal pitch and 4 locations in the longitudinal (circumferential) direction. The volume resistivity was measured and the average logarithmic value was shown as a common logarithm value. The measurement sample was measured after standing for 12 hours in an environment of 23 ° C. and 55% RH.

<Rubber material hardness>
According to JIS K6253, using a durometer A, a bulk (lumb) having a thickness of 6 mm was prepared and evaluated using the material constituting the elastic layer.

<MIT test>
Folding resistance measurement by the MIT test method conforms to JIS P8115 (1994) ("paper and paperboard" in JIS P8115 (1994) is read as "belts obtained in Examples 1-3 and Comparative Examples 1-2") It was measured by using MIT-DA manufactured by Toyo Seiki Co., Ltd. as an MIT testing machine. The test conditions are as follows.

Tip radius of the chuck for bending the test piece: 0.38 mm
Load: 9.8N (1kgf)
Bending angle: 135 ± 2 °
Repeating speed: 175 ± 10 times / minute Repeated bending under the above conditions and applying stress to break. The number of folds until breakage (average value of 5 measurements) was defined as the number of folds.

<Abrasion test>
According to JIS K7204, the weight (mg) of the material ground by the wear wheel was compared by the wear test using the wear wheel. The test conditions are as follows.

Wear wheel type: CS-17
Load: 250g
Number of rotations: 300 times

<Rubber material hysteresis loss>
A test sample having a size of 100 mm square and a thickness of 2 mm was prepared using the elastic layer forming composition, and a dumbbell No. 3 piece was punched out. The test specimen was calculated using the area of the stress-strain curve obtained by the tensile hysteresis loss test (JIS K7312).

<Hysteresis loss measured from the belt surface (belt hysteresis loss)>
The Martens hardness measurement method in ISO 14577-1 Annex A is used. That is, when a test force is pushed in from the surface layer side of the belt with a dynamic micro hardness tester while increasing the test force at a certain rate, and after reaching the specified depth, the test force is unloaded at a certain rate. A stress-strain curve as shown in FIG. 2 is obtained by automatically measuring the depth of the series of indenters. As shown in FIG. 2, let E be the area surrounded by the stress-strain curve. In addition, a perpendicular line is drawn from the point that has reached the specified depth (point A in FIG. 2), and the area of the portion surrounded by the perpendicular line and the curve obtained when the test force is unloaded at a constant rate is F. Then, the hysteresis loss measured from the belt surface side based on these areas E and F is obtained by the following equation.

  Other conditions are as follows.

Testing machine: Shimadzu Dynamic Ultra Hardness Tester DUH-211S
Test mode: Load-unload test Load speed: 0.1463 mN / sec Minimum test force: 0.02 mN
Load holding time: 2 seconds Cf-Ap, with As correction Type of indenter: Triangular 115 (corner angle 115 ° diamond triangular triangular indenter barkovic type)

Example 1
(1) Film formation of base material layer Under nitrogen flow, 47.6 g of 4,4′-diaminodiphenyl ether (ODA) is added to 488 g of N-methyl-2-pyrrolidone, and kept at 50 ° C. and stirred to completely dissolve. I let you. To this solution, 70 g of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) was gradually added to obtain 605.6 g of a polyamic acid solution. This polyamic acid solution had a number average molecular weight of 17,000, a viscosity of 35 poise, and a solid content concentration of 18.0% by weight.

  Next, 21 g of acidic carbon (pH 3.0) and 80 g of N-methyl-2-pyrrolidone were added to 450 g of this polyamic acid solution, and carbon black (CB) was uniformly dispersed by a ball mill. This master batch solution (base layer-forming composition) had a solid concentration of 18.5% by weight and a CB concentration in the solid content of 20.6% by weight.

  And 276g was extract | collected from this solution, the cylindrical mold for base material layer shaping | molding was prepared, and it shape | molded on the following conditions.

  Mold for base material layer molding: a cylindrical mold with an inner diameter of 301.5 mm and a width of 540 mm, with a mirror finish on the inner surface. The mold is placed on two rotating rollers and rotates with the rotation of the rollers. (See, for example, FIG. 3).

  Heating device: a device designed so that a far-infrared heater is disposed on the outer surface of the mold and the inner surface temperature of the mold is controlled to 120 ° C.

  First, 276 g of the solution was uniformly applied to the inner surface of the mold while rotating the cylindrical mold, and heating was started. The heating was performed at a temperature of 1 ° C./min up to 120 ° C., and the heating was continued at that temperature for 60 minutes while maintaining its rotation.

  After completion of the rotation and heating, the mold was removed as it was without cooling, and left in a hot air retention type oven to start heating for imidization. This heating also reached 320 ° C. while gradually raising the temperature. And after heating for 30 minutes at this temperature, it cooled to normal temperature, peeled and took out the semiconductive tubular polyimide belt formed in this metal mold | die inner surface. The belt had a thickness of 80 μm, an outer peripheral length of 944.3 mm, a surface resistivity of 11.5 (log Ω / □), a volume resistivity of 9.2 (log Ω · cm), and a Young's modulus of 4,180 MPa.

(2) Formation of surface layer VdF-HFP copolymer resin (Kyner # 2821, Arkema: HFP 11 mol%) 100 g, which is a copolymer of vinylidene fluoride (VdF) and hexafluoropropylene (HFP), It was dissolved in 900 g of N-dimethylacetamide (DMAc) to prepare a solution A having a solid content concentration of 10% by weight.

  100 g of organically modified montmorillonite (Lucentite STN, manufactured by Coop Chemical Co., Ltd.) was added to 900 g of dimethylacetamide and uniformly dispersed by a ball mill to prepare a solution B having a solid content concentration of 10% by weight.

  Solution A and solution B were prepared at A: B = 99: 1 and mixed with a stirrer to obtain a solution having a solid content of 10% by weight and an organically modified montmorillonite concentration in the solid of 1% by weight. This was diluted with a mixed solvent of DMAc: butyl acetate = 1: 2, solid content concentration 1.6% by weight, organic modified montmorillonite concentration in the solid content 1% by weight (corresponding to the blending ratio of montmorillonite with respect to the total weight of the surface layer) The composition for forming a surface layer was prepared. A film of 112 g of this solution was formed under the following conditions.

  Rotating drum: A metal drum having an inner diameter of 301.0 mm, a width of 540 mm, and an inner surface 10-point average roughness (Rz) = 0.5 μm was placed on two rotating rollers and arranged to rotate with the rotation of the rollers. (See, for example, FIG. 3).

  While rotating the rotating drum, the coating was uniformly applied to the inner surface of the drum and heating was started. The heating was performed at a temperature of 2 ° C./min up to 130 ° C., and heating was performed at that temperature for 60 minutes while maintaining its rotation. After forming a surface layer on the drum inner surface, the drum was cooled to room temperature. It was 2 micrometers when the thickness of the surface layer formed in the drum inner surface was measured with the eddy current type thickness meter (made by Kett Chemical Laboratory).

  In addition, using the above-mentioned composition for forming a surface layer, a surface layer of 10 μm was separately prepared under the same film forming conditions. The 10 μm surface layer had a volume resistivity of 12.6 (log Ω · cm) and a Young's modulus of 610 MPa.

(3) Formation of elastic layer 250 g of acidic carbon (pH 3.5) was added to a solution prepared by dissolving 1000 g of polyurethane elastomer (Pandex FY956, manufactured by DIC Corporation) in 1250 g of xylene, and uniformly dispersed with a ball mill. A master batch solution having a solid concentration of 50% by weight and a carbon black (CB) concentration in the solid content of 20% by weight was prepared. To 250 g of this master batch solution, 8.5 g of a curing agent CLH-5 (manufactured by DIC Corporation) was added and stirred so that the NCO equivalent was 1.1, thereby obtaining an elastic layer forming composition.

  The elastic layer forming composition was uniformly applied to the inner surface of the surface layer on which the film had been formed in advance, and the heating was started. The heating was performed at a temperature of 2 ° C./min up to 130 ° C., and the heating was continued for 120 minutes while maintaining the rotation to form an elastic layer (thickness: 225 μm) on the inner surface of the mold.

  As a preliminary test, the hardness of the urethane cured product produced with this elastic layer forming composition was measured and found to be 42 ° in Type A (JIS K6253). The hysteresis loss by the tensile test of JIS K7312 was 50.6%, and the volume resistivity was 10.9 (log Ω · cm).

(4) Bonding of inner surface of elastic layer and outer surface of base material layer After applying primer DY39-067 (manufactured by Dow Corning Toray Co., Ltd.) to the inner surface of the elastic layer formed in (3) above, air-drying, and then dry dry adhesive The polyimide belt (base material layer) of (1) with a thin coating of (Mitsui Chemical Polyurethane Co., Ltd. Takelac A-969) on the outer surface was inserted and overlapped. Next, heating (80-100 degreeC) was performed in the state crimped | bonded from the base material inner surface, and bonding was completed. The laminated multilayer belt was peeled from the mold, both ends were cut, and a multilayer belt having a width of 360 mm was collected.

  The multilayer belt had a thickness of 330 μm, an outer peripheral length of 945.0 mm, a surface resistivity of 11.7 (log Ω / □), and a volume resistivity of 9.4 (log Ω · cm). The hysteresis loss measured from the belt surface calculated by the Martens hardness measurement method of ISO 14577-1 Annex A was 41.5%.

Example 2
40 g of Sanconol BUAC-30R (trade name, manufactured by Sanko Chemical Co., Ltd.) as an ionic conductive agent was added to a solution obtained by dissolving 988 g of polyurethane elastomer (Urehyper RUP1627, manufactured by DIC Corporation) in 972 g of xylene, and agitator. Uniform dispersion was performed to prepare a master batch solution having a solid content of 50% by weight and an ionic conductive agent concentration of 1.2% by weight in the solid content. To 250 g of this master batch solution, 9.2 g of a curing agent CLH-5 (manufactured by DIC Corporation) was added so as to have an NCO equivalent of 0.9, followed by stirring to obtain an elastic layer forming composition.

  As a preliminary test, when the hardness of the urethane cured product produced with this elastic layer forming composition was measured, it was 40 ° in Type A (JIS K6253). The hysteresis loss by the tensile test of JIS K7312 was 29.8%, and the volume resistivity was 10.3 (log Ω · cm).

  A multilayer belt was produced in the same manner as in Example 1 except that this elastic layer forming composition was used.

  As a result, the hysteresis loss measured from the surface of the belt calculated by the ISO 14577-1 Annex A Martens hardness measurement method of the produced multilayer belt was 23.4%.

Example 3
Instead of VdF-HFP copolymer resin (Kainer # 2821, Arkema: HFP 11 mol%) which is a copolymer of vinylidene fluoride (VdF) and hexafluoropropylene (HFP) in Example 1 (2) (PVdF resin ( A multilayer belt was produced in the same manner as in Example 1 except that Kyner # 301F) was selected.

  Using this composition for forming a surface layer, a surface layer having a thickness of 10 μm was separately prepared under the same film forming conditions. The Young's modulus of the surface layer was 1,920 MPa. As a result, the hysteresis loss measured from the belt surface calculated by the ISO 14577-1 Annex A Martens hardness measurement method of the produced multilayer belt was 39.3%.

Comparative Example 1
The base material (1) in Example 1 was used as a polyimide single layer belt for each evaluation.

Comparative Example 2
A multilayer belt was produced in the same manner as in Example 2 except that 11.7 g of the curing agent was added in Example 2 so that the NCO equivalent was 1.1.

  As a preliminary test, the hardness of the urethane cured product prepared with this elastic layer forming composition was measured and found to be 43 ° with Type A (JIS K6253). The hysteresis loss by the tensile test of JIS K7312 was 17.9%, and the volume resistivity was 10.2 (log Ω · cm).

  As a result, the hysteresis loss measured from the belt surface calculated by the ISO 14577-1 Annex A Martens hardness measurement method of the produced multilayer belt was 17.0%.

  Tables 1 and 2 show the results of the following image evaluation and durability results obtained by incorporating the sample multilayer belts of Examples 1 to 3 and Comparative Examples 1 and 2 into the MIT test and the abrasion test and the transfer unit. .

<Primary and secondary transfer efficiency>
The primary transfer efficiency was determined from the following equation by measuring the toner weight on the photoreceptor before and after transfer. The secondary transfer efficiency was determined from the following equation by measuring the toner weight on the transfer belt before and after transfer.

Each transfer efficiency was evaluated according to the following criteria.
(Primary transfer efficiency)
○: higher than 97% △: 95-97%
×: Less than 95% (secondary transfer efficiency)
○: higher than 95% △: 90-95%
×: Less than 90%

<Thin wire hollow>
The hollow line image was observed on the transfer belt before the secondary transfer and evaluated. As for the thin line, a solid image thin line of two colors Y and M parallel to the transfer belt traveling direction of about 0.05 mm is observed with a laser microscope at a magnification of 300 times, and several hollows are generated within 1 mm of the thin line length. It was evaluated according to the following criteria.
○: There is no void at all. Δ: There are 1 to 4 voids. ×: There are 5 or more voids.

<Concavity and convexity followability of paper (rough paper transferability)>
Using “Rezac 66” (surface unevenness difference 80 μm, 151 g / m ² ) of Fuji Xerox Office Supply Co., Ltd. as the paper with large irregularities, solid printing with cyan, visually seeing the toner in the deepest part (concave part), Evaluation was made according to the following criteria.
○: The image is transferred evenly. Δ: Slightly missing. ×: There is no toner and the image is missing.

<Paper passing durability test>
Paper feeding, energization, and driving tests were simultaneously performed under the following conditions. After driving tests equivalent to 100,000 sheets, the presence or absence of peeling or cracking of the surface layer was observed with a microscope, and evaluated according to the following criteria.
○: No peeling or cracking of surface layer ×: Microcracking Drive speed: Belt outer peripheral speed 300 mm / sec Energization: Supplying a constant current of 50 μA in the belt thickness direction by a power supply (Trek 610C) Paper passing: Secondary transfer roll A copy paper is wrapped around the outer surface to produce a state in which the paper is continuously simulated. Cleaning mechanism: Cleaning blade made of urethane rubber (rubber hardness type A 80 °)

  In the examples, since the hysteresis loss measured from the belt surface side is 20% or more, it can be seen that the number of MIT tests is greatly improved by the effect of following the elastic layer of the polyimide to the base material layer (comparison). Comparison with Example 1). Further, there was no occurrence of cracking or peeling in durability evaluation due to the effect of following the elastic layer to the surface layer. Furthermore, there were no defects in the thin line in the primary transfer, which is the main purpose of providing the rubber elastic layer, and the followability to the unevenness of the paper in the secondary transfer was also good.

  In Comparative Example 2, the hysteresis loss measured from the surface side of the belt was less than 20%, and many minute cracks were generated in the durability evaluation. This is because the rubber elastic layer applied the stress received by the surface layer from a cleaning blade or the like. It is presumed that the reaction force of the rubber to repel the stress is generated and the force that attacks the surface layer is changed. If a minute crack occurs on the belt surface, the crack grows large and the toner cleaning property deteriorates, and the toner adheres to the belt surface, so that the transfer to the paper cannot be performed well.

  As described above, the multilayer elastic belt for an electrophotographic apparatus of the present invention is provided with a specific elastic layer, thereby providing a primary transfer characteristic with clear image printing and fine line printing, followability to irregularities on the surface of the medium, and toner. The secondary transfer characteristics such as releasability are good, and the hysteresis loss measured from the surface side of the belt is 20% or more, so that the flexibility of the belt is increased and the bending durability is improved. In addition, the friction durability of the surface layer against the cleaning blade or the like could be improved.

Claims (6)

In order from the surface side, a multilayer elastic belt for an electrophotographic apparatus comprising at least three layers of a surface layer containing a releasable material, an elastic layer containing an elastic rubber material, and a base material layer containing a high-strength resin material,
A multilayer elastic belt for an electrophotographic apparatus having a hysteresis loss of 20% or more calculated from the result of dynamic microhardness measurement (ISO 14577-1) measured from the surface side. 2. The multilayer elastic belt for an electrophotographic apparatus according to claim 1, wherein the Young's modulus of the surface layer is 2,000 MPa or less and the thickness of the surface layer is 5 μm or less. The multilayer elastic belt for an electrophotographic apparatus according to claim 1, wherein the releasable material is a fluororesin and / or a fluororubber. The multilayer elastic belt for an electrophotographic apparatus according to any one of claims 1 to 3, wherein the material constituting the elastic layer has a type A hardness of 20 ° or more. The multilayer elastic belt for an electrophotographic apparatus according to any one of claims 1 to 4, wherein the elastic rubber material is a polyurethane elastomer material, and a hysteresis loss of a cured product of the polyurethane elastomer material alone is 20% or more. The high-strength resin material is at least one material selected from the group consisting of polyimide, polyamideimide, polycarbonate, PVdF, polyamide, and ethylene-tetrafluoroethylene copolymer. Multilayer elastic belt for electrophotographic devices.

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