JP2009265343A - Multilayer elastic belt used for image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer elastic belt having good electric characteristics as a transfer belt and easily ensuring qualities of electric characteristics because a resistivity in each layer can be independently measured. <P>SOLUTION: The multilayer elastic belt for an electrophotographic device is produced by separately manufacturing a first belt comprising at least two layers of a surface layer containing a release material and an elastic layer containing an elastic rubber material, and a second belt comprising a base layer containing a high strength resin material, then laminating the elastic layer side of the first belt with the second belt. The common logarithm V<SB>1</SB>of the volume resistivity (Ω cm) of the first belt when 100 V is applied at 23°C and 55% RH and the common logarithm V<SB>2</SB>of the volume resistivity (Ω cm) of the second belt when 100 V is applied at 23°C and 55% RH satisfy V<SB>1</SB>>V<SB>2</SB>. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

  In order to cope with the high image quality of the intermediate transfer belt, as described in Patent Document 1, an intermediate transfer belt having a two-layer or three-layer structure having an elastic material layer has been proposed.

  Further, Patent Document 2 and the like have devised one using urethane rubber for the elastic layer, and Patent Document 3 and the like have devised one using silicone rubber for the elastic layer. These belts are usually formed by a method in which an elastic layer and a surface layer are sequentially coated on the surface of a resin belt such as polyimide as a base material layer, a method in which an elastic layer and a base material layer are sequentially molded on the inner surface of a mold, a calendar roll, etc. Manufactured by laminating sheeted sheets.

  Since the intermediate transfer belt formed of such a rubber elastic body or provided with a rubber elastic body layer is excellent in flexibility, it can easily and stably form a transfer area with a photosensitive member etc. in contact with the intermediate transfer belt. In addition, the stress applied to the toner between the photosensitive member and the like is reduced, which is useful for countermeasures against image dropout defects and for improving the sharpness of fine line printing.

  Further, such an intermediate transfer belt for high image quality achieves the purpose of imparting elasticity in the thickness direction of the belt, while toner releasability required for a conventional transfer belt is simultaneously required as an important factor. That is, in order to transfer toner from the surface of the intermediate transfer belt to a medium such as paper, releasability with respect to the toner is required. Therefore, the member constituting the surface layer may be made of fluorine rubber, silicone rubber, fluorine resin material, or the like. By forming it with a material having a low surface energy, it is easy to release the toner from the surface of the intermediate transfer belt, and it has been successfully used to improve transfer efficiency.

  However, in the intermediate transfer belt, not only the physical requirements as described above, but also electrical characteristics such as surface resistivity and volume resistivity are very important. In general, if the surface resistivity of the intermediate transfer belt is too higher than a predetermined range, a discharge occurs between the intermediate transfer belt and the photoconductor in the latter half of the nip during the primary transfer, resulting in a blank image. On the other hand, if the surface resistivity is too lower than the predetermined range, the charge at the time of primary transfer escapes along the surface of the intermediate transfer belt, so that the toner is scattered before entering the nip portion and the image is deteriorated.

  Further, if the volume resistivity of the intermediate transfer belt is too higher than a predetermined range, the surface of the intermediate transfer belt is charged up by the primary transfer transfer electric field, and a static elimination mechanism is required. On the other hand, if the volume resistivity is too lower than the predetermined range, even if a charge is applied to the intermediate transfer belt due to the bias, the charged charge escapes due to its conductivity, and sufficient electrostatic force to hold the toner cannot be obtained. Transfer efficiency is significantly reduced.

  Furthermore, even if the resistance control range of each of the surface resistivity and volume resistivity of the intermediate transfer belt is within a predetermined range, a good function may not be obtained depending on their relative relationship. This is described in Patent Document 4 or Patent Document 5. That is, the electrical basic performance of the intermediate transfer belt is required to have at least a surface resistivity value larger than a volume resistivity value.

  Next, when considering controlling the electrical characteristics of an intermediate transfer belt having a multilayer structure, there is no excellent literature on this. In order to give the intermediate transfer belt having a multilayer structure the range of effective surface resistivity and volume resistivity as known intermediate transfer belts as described above and the relationship between them, what is the resistivity of each layer alone? It was a recent research subject to determine whether it should be controlled.

Patent Document 6 proposes an equation showing the relationship between the surface resistivity of the intermediate layer and the base material layer. However, when the relationship is satisfied, it is not described what the critical resistivity of the completed intermediate transfer belt of the multilayer structure is. Moreover, in such a manufacturing method, the resistivity of each of the intermediate layer and the base material layer cannot be measured. In other words, the resistivity of each of the intermediate layer and the base material layer only describes the resistivity of the material constituting them, and does not discuss the directly measured resistivity of each layer after actual molding. The quality assurance for the resistivity at the time of conversion becomes very ambiguous. Furthermore, it is desirable to use the surface layer to obtain a large surface resistivity as a transfer belt. However, when the insulating surface layer is actually coated on the order of several μm, it describes how much it affects the resistivity of the transfer belt. There is no.
Japanese Patent No. 3248455 Japanese Patent Laid-Open No. 2001-282009 JP 2002-292655 A Japanese Patent Laid-Open No. 10-228188 JP 2006-330692 A JP 2007-292887 A

  As described above, in the prior art, it has been difficult to obtain a means for imparting an electrical property, that is, an optimal balance between surface resistivity and volume resistivity, to a transfer belt having a multilayer structure.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a multilayer elastic belt that has good electrical characteristics as a transfer belt and can easily guarantee the quality of electrical characteristics by allowing the resistivity of each layer to be measured independently.

  As a result of earnest research to solve the above problems, the present inventor has found that a first belt (hereinafter referred to as “first belt”) comprising at least two layers of a surface layer made of a releasable material and an elastic layer made of an elastic rubber material. Multi-layer elastic belt for electrophotographic apparatus, which is manufactured by separately manufacturing a second belt made of a high-strength resin material (hereinafter also referred to as “second belt”) and bonding them together. The manufacturing method of was found. By doing so, the resistivity of the first belt and the second belt before bonding can be measured, and the individual resistivity for obtaining the target resistivity as the transfer belt can be confirmed. By using such a manufacturing method, it has become possible to elucidate the mechanism of the resistivity expression of multilayer structures that have not been studied so far. According to the studies by the inventors, the surface resistivity in the multilayer structure film is strongly influenced by the lowest value of the surface resistivity of each layer alone, and the volume resistivity is within the volume resistivity of each layer alone. It was found to be strongly influenced by the highest value.

  In the example of the intermediate transfer belt, as described above, the electrical basic performance is required to have at least a surface resistivity value larger than a volume resistivity value. When the intermediate transfer belt is made of a single resin, this balance can usually be ensured. This is because in the case of a single material, there is a correlation between the surface resistivity and the volume resistivity. However, when a surface layer made of a releasable material, an intermediate layer using elastic rubber, and a base material layer made of high-strength resin are stacked to form a multilayer structure belt, resistance adjustment that is good for transfer for each material Even when applied, the resistance balance of the completed multilayer belt usually has a surface resistivity in the range of about 1/10 to 10 times the volume resistivity. That is, the value of the surface resistivity is not necessarily larger than the value of the volume resistivity, and shows individual behavior. As can be seen from this, in the case of a multilayer structure belt, there is no correlation between the surface resistivity and the volume resistivity. This is considered to be due to the fact that the surface resistivity of the rubber film, which is a constituent material of the intermediate layer, is about 10 times the volume resistivity, and the difference between the two is relatively small.

  On the other hand, when a multilayer belt is used for a paper conveyance belt that requires a relatively low resistance as well as a surface elasticity or a transfer belt for liquid toner, the resistivity of the intermediate layer rubber is easier to adjust than the base layer. However, even if the volume resistivity of the intermediate layer is lower than the volume resistivity of the base material layer, the volume resistivity of the multilayer belt does not become lower than the volume resistivity of the base material layer. The reason is presumed that in the multilayer structure film, the volume resistivity value of the layer having the highest volume resistivity in the thickness direction becomes the volume resistivity of the multilayer structure film itself. As a result, even if the volume resistivity of the rubber material is lowered, the volume resistivity of the base material layer becomes the transfer belt volume resistivity as it is.

  From the above, in order to obtain a multilayer transfer belt having a surface resistivity greater than the volume resistivity by using rubber with a small difference between the surface resistivity and the volume resistivity, the volume resistivity of the rubber layer The volume resistivity of the substrate layer must be low. However, if the resistance of the base material layer is too low, if a charge bias is applied to the transfer belt from the base material layer side, the charge will diffuse through the base material layer, so grasp the lower limit that does not happen. There is a need.

  Similarly, it was found that the surface resistivity of the multilayer structure was dominated by the surface resistivity of the lowest layer. From this, the surface resistivity and volume resistivity were originally found. In order to obtain a multi-layer transfer belt having a surface resistivity greater than the volume resistivity using a rubber having a small difference, the surface resistivity of the base material layer must be higher than the surface resistivity of the rubber layer. It is self-explanatory.

In addition, since the intermediate transfer belt electrically transfers toner, it has been conventionally considered that the base material layer, the elastic intermediate layer, and the surface layer preferably have semiconductivity. However, the inventors have found that the surface layer does not necessarily require semiconductivity. That is, when the resistance value of the surface layer decreases, a bias current for transferring an image runs on the surface layer, and the bias current does not flow perpendicular to the thickness direction. As a result, image defects such as transfer of toner having a color different from the color desired to be placed on the intermediate transfer belt occur. Therefore, the surface layer does not necessarily need semiconductivity. More importantly, when the surface layer is a thin film of several μm or less composed of an insulating material having a volume resistivity of 10 ¹³ Ω · cm or more, the electrical characteristics of the completed transfer belt having a multilayer structure is obtained. There is no influence on the level, or the level is extremely small and can be ignored. Needless to say, this can be said similarly in the case of a two-layer film of a surface layer and an elastic layer.

  Based on this knowledge, the present invention has been completed through further research on how to control the resistivity of each layer in order to develop the resistivity balance required for the transfer belt.

  That is, the present invention provides the following elastic belt.

Item 1: A first belt composed of at least two layers of a surface layer containing a releasable material and an elastic layer containing an elastic rubber material, and a second belt made of a base material layer containing a high-strength resin material are manufactured separately. A multilayer elastic belt for an electrophotographic apparatus, comprising an elastic layer side of the first belt and a second belt,
The common logarithm value V ₁ of the volume resistivity (Ω · cm) of the first belt at 100 ° C. applied at 23 ° C. and 55% RH, and the volume resistivity at the time of 100 V application of the second belt at 23 ° C. and 55% RH ( A multilayer elastic belt for an electrophotographic apparatus, wherein a common logarithmic value V ₂ of Ω · cm) satisfies V ₁ > V ₂ .

Item 2 The common logarithm of the surface resistivity (Ω / □) of the first belt at 100 ° C. applied at 23 ° C. and 55% RH is S ₁ at 23 ° C. and 55% RH when 100 V of the second belt is applied. when the surface resistivity of the common logarithm of (Ω / □) was _{S 2, S 1> V 1} , S 2> V 2, and _S 1 <multilayered elastic electrophotographic apparatus according to claim 1 satisfying _{S 2} belt.

Item 3. The multilayer elastic belt for an electrophotographic apparatus according to Item 1 or 2, wherein the elastic layer is a layer containing a polyurethane elastomer having an insulating property with a volume resistivity of 10 ¹³ Ω · cm or more and carbon black.

Item 4 The multilayer elastic belt for an electrophotographic apparatus according to Item 1 or 2, wherein the elastic layer is a layer containing a polyurethane elastomer having a volume specific resistivity of 10 ¹³ Ω · cm or more and a lithium salt.

Item 5 The multilayer for an electrophotographic apparatus according to Item 1 or 2, wherein the surface layer is a layer containing a fluororesin material having an insulating property with a volume resistivity of 10 ¹³ Ω · cm or more, and the thickness thereof is 5 μm or less. Elastic belt.

Item 6 When V ₁ and V ₂ are in the range of 7 ≦ V ₁ ≦ 13, 4 ≦ V ₂ ≦ 12.5, the surface of the multilayer elastic belt for an electrophotographic apparatus at 23 ° C. and 55% RH when 100 V is applied when the common logarithm of the resistivity (Ω / □) was _{S 12,} a volume resistivity of the common logarithm of (Ω · cm) and _{V 12,} electrophotography according to claim 1 or 2 satisfying the S _{12> V 12} Multi-layer elastic belt for equipment.

  Item 7 The multilayer elastic belt for an electrophotographic apparatus according to Item 1 or 2, wherein a shape of the multilayer elastic belt for an electrophotographic apparatus is endless.

  Item 8 The multilayer elastic belt for an electrophotographic apparatus according to Item 1 or 2, wherein the material of the base material layer is polyimide or polyamideimide.

Item 9. A method for producing a multilayer elastic belt for an electrophotographic apparatus,
(1) A first belt consisting of at least two layers of a surface layer containing a releasable material and an elastic layer containing an elastic rubber material and a second belt consisting of a base material layer containing a high-strength resin material are manufactured separately. Process,
(2) Common logarithmic value V ₁ of volume resistivity (Ω · cm) when applying 100V of the first belt at 23 ° C. and 55% RH, and applying 100V of the second belt at 23 ° C. and 55% RH A step of measuring a common logarithm value V ₂ of the volume resistivity (Ω · cm) and confirming that V ₁ > V ₂ , and (3) an elastic layer side of the first belt and a second belt A manufacturing method comprising a step of manufacturing a multilayer elastic belt for an electrophotographic apparatus by bonding.

Item 10 Further, in the step (2), the common logarithm value S ₁ of the surface resistivity (Ω / □) at the time of applying 100V to the first belt at 23 ° C. and 55% RH, and at 23 ° C. and 55% RH The common logarithm value S ₂ of the surface resistivity (Ω / □) when 100 V is applied to the second belt is measured, and it is confirmed that S ₁ > V ₁ , S ₂ > V ₂ , and S ₁ <S _2. Item 10. A method for producing a multilayer elastic belt for an electrophotographic apparatus according to Item 9, comprising a step.

  In the multilayer elastic belt of the present invention, the resistivity of each layer can be individually controlled in the manufacturing process, so that a balance between surface resistivity and volume resistivity suitable for a transfer belt can be established. As a result, when assembled in an electrophotographic apparatus, the transfer belt does not suffer from problems such as scattering of a toner image carried on the surface, transfer failure due to insufficient carrying force, and charge up of the belt surface.

Hereinafter, the present invention will be described in detail.
I. Formation of the surface layer The surface layer in the multilayer elastic belt (especially the intermediate transfer belt) of the present invention is a layer on which toner is directly placed and the superimposed four color toners are transferred to paper and released.

  Examples of the material for the surface layer include a releasable material from the viewpoint of facilitating the release of the toner. Examples of such fluororesins include polytetrafluoroethylene (PTFE), tetrafluoroethylene / perfluoroalkyl vinyl ether (PFA), tetrafluoroethylene, hexafluoropropylene, vinylidene fluoride copolymer (THV), and polyvinylidene fluoride. Ride (PVDF), a copolymer of vinylidene fluoride (VDF) and hexafluoropropylene (HFP) (VDF-HFP copolymer), or a mixture thereof. The copolymer of VDF and HFP preferably has a HFP ratio of about 1 to 15 mol%.

  Many fluororesin materials alone are difficult to adhere to the rubber constituting the elastic layer. In this case, urethane resin or acrylic resin may be used as the binder. However, tetrafluoroethylene, hexafluoropropylene, vinylidene fluoride copolymer (THV), polyvinylidene fluoride (PVDF), vinylidene fluoride (VDF) and hexafluoropropylene (HFP) copolymer (VDF-HFP) When a copolymer) or a mixture thereof is selected, adhesion to rubber is relatively easy by using a primer or the like because of its large surface energy.

  Further, a fine powder of polytetrafluoroethylene (PTFE) may be added to these fluororesin materials. In this case, the powder may be directly dispersed in a raw material solution to be described later, or a dispersion previously diluted with a solvent or the like may be used, and the polytetrafluoroethylene fine particle powder relative to the weight of the fluororesin material in the raw material solution The body can be added in an amount of 20% by weight or less, preferably 10% by weight or less.

The volume resistivity of the surface layer is usually 10 ¹³ Ω · cm or more, more preferably 10 ¹³ to 10 ¹⁵ Ω · cm. In addition, as described in the section of means for solving the problem, it is possible to control the semiconductivity by adding a conductive agent such as carbon black. However, the effect is limited and has a demerit. The layer is substantially free of a conductive agent. “Contains substantially no conductive agent” means that the content of the conductive agent is 3.0 parts by weight or less with respect to 100 parts by weight of the releasable material (fluororesin) in the surface layer. 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.

  When the area of the surface layer is constant, the thickness of the surface layer is preferably 1 to 5 μm, 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, and if the thickness is too thin, there is a problem in durability such that a hole is easily formed in the surface layer.

  The static friction coefficient of the surface layer is preferably 0.1 to 0.5, more preferably 0.15 to 0.35, and particularly preferably 0.2 to 0.3 from the viewpoint of preventing blade squeal.

  The surface roughness (Rz) of the surface layer is 0.1 to 3.5 μm, preferably 0.25 to 2.5 μm, more preferably 0.4 to 1.5 μm. When the surface roughness Rz is less than 0.1 μm, it tends to stick to a sliding member such as a roll, which causes torque over during driving. When it exceeds Rz 3.5 μm, toner adhesion ( This is not preferable because it causes image defects such as filming and voids.

As a typical example, the surface layer is formed by centrifugally molding a fluororesin having a volume resistivity of 10 ¹³ Ω · cm or more using a cylindrical mold having a surface roughness (Rz) of 0.1 to 3.5 μm. explain.

  First, the weight of the material is adjusted so that the finished surface layer has a target thickness of 1 to 5 μm. The weighed surface layer material is dissolved in a solvent to obtain a liquid raw material, which is cast on the inner surface of a cylindrical mold and centrifuged. 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 is used. The liquid raw material may have a solid content concentration of about 2 to 30% by weight.

  Centrifugal molding of the surface layer can be performed as follows using, for example, a cylindrical mold. After injecting the liquid raw material in an amount equivalent to obtaining the final thickness into the stopped cylindrical mold, the rotational speed is gradually increased to the speed at which the centrifugal force works, and the centrifugal force uniformly flows over the entire inner surface. Extend.

  The cylindrical mold is plated after its inner surface is polished to a predetermined surface accuracy, and the surface state of this mold is transferred to the outer surface of the surface layer of the endless multilayer elastic belt. Therefore, the surface roughness of the surface layer can be adjusted to a desired range by controlling the surface roughness of the inner surface of the mold. Note that the roughness of the inner surface of the mold to be used can be arbitrarily controlled by the count of the abrasive paper used when finishing the inner surface. Further, the surface roughness before plating may be controlled by blasting to the inner surface of the mold.

  Further, a release agent is applied to the inner surface of the cylindrical mold so that the film after the raw material is cured can be released from the inner surface of the mold. As the release agent, a fluorine release agent or a silicone release agent 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 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 150 to 200 ° C. and heated at the temperature after the temperature raising for about 0.5 to 2 hours. Thereby, the liquid raw material 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.
II Formation of Elastic Layer The elastic layer in the multilayer elastic belt of the present invention is made of an elastic rubber material, specifically, a cured product of liquid urethane rubber. For example, it is manufactured by applying and curing a liquid urethane rubber and, if necessary, an elastic layer material containing an electronic conductive agent or an ionic conductive agent in the liquid urethane rubber on the inner surface of the surface layer obtained in I above .

  Examples of the liquid urethane rubber include polyurethane elastomers, and those having a cured product of type A hardness (JIS K6253) of 30 to 80 degrees, more preferably 40 to 65 degrees are preferred. Specific examples include Pandex and Urehyper manufactured by Dainippon Ink and Chemicals, Takenate manufactured by Mitsui Chemicals Polyurethanes, and the like.

Usually, some of these urethane rubbers have a volume resistivity of about 10 ⁹ Ω · cm to 10 ¹¹ Ω · cm without adjusting the resistance. In many cases, the environmental variation is large when the temperature and humidity environment is shaken. Accordingly, it is desirable to select a urethane rubber having a volume resistivity of 10 ¹³ Ω · cm or more that is not originally adjusted for resistance. The resistance of this urethane rubber is adjusted with a conductive agent whose electrical characteristics are less dependent on the environment, that is, carbon black or lithium ion salt.

  The carbon black may be a conductive carbon black such as acetylene black or ketjen black. The compounding amount of carbon black is 5 to 40 parts by weight, preferably 10 to 30 parts by weight, and more preferably 10 to 25 parts by weight with respect to 100 parts by weight of the liquid urethane rubber.

Thus, by adding carbon black to the insulating 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. The As a result, accurate semiconductivity suitable for various purposes can be obtained. 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 the ion conductive agent using a lithium salt include lithium bisimide (CF ₃ SO ₂ ) ₂ NLi, lithium trismethide (CF ₃ SO ₂ ) ₃ CLi, and the like. Specific examples include Sanconol manufactured by Sanko Chemical Co., Ltd. In the type of a normal ionic conductive agent, the conductivity is considered to be manifested by moisture absorption, which causes the ionic conductivity to depend on the environment. However, this ionic conductive agent, which is considered to develop conductivity by the movement of lithium ions due to the molecular motion of oxygen, is less dependent on the environment, and is suitable for use as an elastic layer rubber for transfer belts. It is done. When an ionic conductive agent is added, the addition amount is about 0.1 to 3.0 parts by weight with respect to 100 parts by weight of the liquid urethane rubber.

  The liquid urethane material whose resistance is adjusted by any of the methods in this way is put into the inner surface of the surface layer formed on the inner side of the mold and is centrifugally molded. If the viscosity of the liquid urethane material 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 molding equipment for the I surface layer is used. The molding temperature is gradually heated from room temperature, raised to about 120 to 150 ° C., which is below the heat resistance limit of urethane rubber, and kept in this state for about 0.5 to 1 hour 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.
III. Formation of Base Material Layer The base material layer in the multilayer elastic belt of the present invention is a layer for preventing deformation due to stress applied to the belt during driving. Therefore, mechanical properties are required.

  Examples of the resin for the base material layer include high-strength resin materials such as polyimide and polyamideimide.

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

  Examples of polyimide tetracarboxylic dianhydrides include pyromellitic acid, naphthalene-1,4,5,8-tetracarboxylic acid, naphthalene-2,3,6,7-tetracarboxylic acid, 2,3,5,6. -Biphenyltetracarboxylic 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-di-carboxyphenyl) 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.

  As said diisocyanate, the compound etc. which the amino group in the above-mentioned diamine component substituted by the isocyanate group are mentioned.

  Polyamideimide is produced by condensation polymerization of trimellitic acid and diamine or diisocyanate by a known method. In this case, the same diamine or diisocyanate as the above-mentioned polyimide raw material can be used.

  The thickness of the base material layer is usually 30 to 120 μm, 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 a conductive agent is included, the amount used is usually about 5 to 25 parts by weight with respect to 100 parts by weight of the base layer resin. As a result, the base material layer can have a resistivity suitable for the intermediate transfer belt.

  When polyimide is used as the resin for the base material layer, for example, the base material layer can be formed as follows. Tetracarboxylic dianhydride, which is the raw material of the polyimide, and diamine are reacted in a solvent to obtain a polyamic acid solution once. This polyamic acid solution should just be about 10 to 40 weight% by solid content concentration.

  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, hexamethylphospho An aprotic organic polar solvent such as amide 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, as described above, about 5 to 25 parts by weight of conductive agent such as carbon black is added to the polyamic acid solution with respect to 100 parts by weight of the base material resin as necessary. You may do it. In this case, the carbon black may be uniformly dispersed with a ball mill. Thereby, the material for base material layers containing a polyamic acid and a electrically conductive agent as needed is obtained.

  The obtained material for the base layer is subjected to centrifugal molding using a cylindrical mold or the like in the same manner as the surface layer / elastic layer. 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 raising 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 and separately imidized. For heating to 280 to 400 ° C. The time required for this imidization is usually about 20 minutes to 3 hours.

  Similarly, when polyamide imide is used as the resin for the base material layer, diamine or diisocyanate derived from diamine and trimellitic acid are reacted in a solvent to directly form polyamide imide, and this is subjected to centrifugal molding to produce a joint. (Seamless) polyamideimide base material layer can be formed. In addition, in order to impart desired semiconductivity to the base material layer, a conductive agent such as carbon black as described above may be added to about 5 to 25 parts by weight with respect to 100 parts by weight of the base material layer resin as necessary. May be added.

  The base material layer formed using centrifugal molding is different from the above-described cylindrical mold used for forming the surface layer and rubber elastic layer in terms of the shrinkage rate of the raw material and the heat-resistant temperature. It is preferable to use a dedicated mold.

  The Young's modulus of the polyimide or polyamideimide thus obtained by centrifugal molding is usually 2500 MPa or more.

  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. You may add electrically conductive agents, such as above-mentioned carbon black, so that it may become about 5-25 weight part with respect to 100 weight part of base material layer resin.

  The resins that can be extruded are as described above. In this case, in order to maintain the performance as a substrate, a material having a Young's modulus of 1000 MPa or more, preferably 1500 MPa or more can be selected.

The volume resistivity of the base layer, from the viewpoint of performing transfer by electrical control of the toner as a belt substrate, usually 10 ⁴ ~10 ^12.5 Ω · cm approximately, - preferably 10 ⁹ to 10 ^12.5 Omega It is about cm.

As described above, a base material layer having a seamless high strength can be obtained.
IV Formation of multilayer elastic belt (three layers)
Finally, layers formed separately by centrifugal molding in II and III above, that is, a first belt composed of two layers of an integrated surface layer and an elastic layer, and a base material layer composed of a high-strength resin material Are overlapped so that the inner surface of the first belt (the surface on the elastic rubber layer side) 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.

  According to this method, each surface resistivity and volume resistivity can be easily measured before bonding the first belt and the second belt, and it is easily judged whether or not the desired resistivity is achieved. it can.

Specifically, the first belt volume resistivity and common logarithm V ₁ of the (Ω · cm), the volume resistivity of the second belt common logarithm V ₂ of (Ω · cm) was measured, both measurements Confirms that V ₁ > V ₂ . V ₁ and V ₂ are preferably in the range of 7 ≦ V ₁ ≦ 13, 4 ≦ V ₂ ≦ 12.5, and more preferably in the range of 8.5 ≦ V ₁ ≦ 11 and 7 ≦ V ₂ ≦ 10.5. This is because the volume resistivity of the completed multilayer belt depends on the volume resistivity of the rubber elastic layer.

The surface resistivity of the first belt and common logarithm S ₁ of (Ω / □), a common logarithm value S ₂ of the surface resistivity of the second belt (Ω / □) was measured, the measured value of both S It is confirmed that 3> ₁ > V ₁ , S ₂ > V ₂ , and S ₁ <S ₂ are satisfied.

  Whether the balance of resistivity as described above is ensured can be confirmed before the three-layer process. The presence or absence of an adhesive or primer applied as necessary in this step has no effect on the resistance development of the multilayer elastic belt.

  Specific examples of the three-layer process will be given. A laminate adhesive is uniformly applied to the inner surface (surface on the elastic rubber layer side) of a two-layer film (first belt) made of a surface layer and an elastic rubber layer regulated by the inner surface of the cylindrical mold, and air-dried. A primer is also applied to the outer surface of the separately formed base material layer (second belt) and air-dried, and then this is overlaid on the inner surface of the elastic rubber layer, and the inner metal is in close contact with the inner surface of the base material layer so as not to be displaced. Insert a type.

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

  Here, it can be seen that when the adhesive is cured at room temperature and when it is cured under heating, the resistance of the multilayer elastic belt is not affected at all, and the heating temperature is appropriate. ing. Therefore, each surface resistivity and volume resistivity before bonding the first belt and the second belt, and each surface resistivity measured after peeling off the first belt and the second belt after bonding. The volume resistivity indicates the same value except for the measurement error range.

  Examples of the laminating adhesive include Takelac A-969 manufactured by Mitsui Chemicals Polyurethane Co., Ltd. and Tyforce NT-810 manufactured by Dainippon Ink & Chemicals, Inc. 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.

The common logarithm value S ₁₂ of the surface resistivity (Ω / □) and the common log value V ₁₂ of the volume resistivity (Ω · cm) of the obtained multilayer elastic belt are measured. At this time, it is confirmed that S ₁₂ > V ₁₂ is satisfied. This is to obtain a resistance balance for preventing toner image scattering, transfer failure due to insufficient carrying force, belt surface charge-up, and the like when used as a transfer belt.

S ₁₂ is preferably in the range of 10 ≦ S ₁₂ ≦ 14, more preferably 11 ≦ S ₁₂ ≦ 13, and V ₁₂ is preferably in the range of 7 ≦ V ₁₂ ≦ 12, and further 9 ≦ V ₁₂ ≦ 11.

  The outer peripheral length of the multilayer elastic belt can be appropriately selected depending on the use mode of the electrophotographic belt, but is usually about 300 to 2500 mm.

  Since the multilayer elastic belt of the present invention has a surface resistivity larger than its volume resistivity, toner scattering does not occur due to a good transfer electric field, and the high-definition characteristic of the rubber elasticity imparting belt is high. It can be used as a semiconductive belt from which an image can be obtained.

  The total thickness of the multilayer elastic belt is usually 100 to 500 μm, preferably 200 to 400 μm, and more preferably 250 to 350 μm. Such a thickness is preferable because the effect of elasticity is sufficient. In addition, the ratio of the thickness of a surface layer, an elastic layer, and a base material layer is 5: 5-9: 1 normally, Preferably it is 6: 4-8: 2.

  As described above, the multilayer elastic belt of the present invention is suitably used as an electrophotographic belt such as an intermediate transfer belt, a transfer conveyance belt, a paper conveyance belt, or a transfer fixing 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.
<Base layer solid content concentration>
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. Put the heat-resistant container containing the sample in an electric oven, heat and dry while heating up in order of 120 ℃ × 12min, 180 ℃ × 12min, 260 ℃ × 30min, and 300 ℃ × 30min. The weight of the solid content (solid content weight) is 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.

Base material layer solid content concentration = B / A x 100 (%) (I)
<Surface layer and elastic layer solids concentration>
The raw material is precisely weighed, and the weight of the solid 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).

Elastic layer solid content concentration = C / D x 100 (%) (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 probe of a contact-type film thickness measuring instrument.
<Surface resistivity, volume resistivity>
Surface resistivity (Ω / □) and volume resistivity (Ω · cm) were measured at 23 ° C and 55% RH using a resistance meter “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 10 seconds after an applied voltage of 100 V at a total of 12 points in the width direction of the sample, 3 places at equal pitch and 4 places 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.
<Static friction coefficient>
The static friction coefficient was measured using 10 different surface parts within the same belt using Heidon 94i manufactured by Shinto Kagaku Co., Ltd., and the average value was taken as the static friction coefficient.
<Surface roughness (Rz)>
The surface roughness (μm) was measured according to JIS B0601-1982. As a measuring machine, Surfcom 575A manufactured by Tokyo Seimitsu Co., Ltd. was used. The measurement conditions were CUTOFF 0.25, measurement length 2.5 mm, and T-SPEED 0.06 mm / s. Five different surface portions were measured in the same belt, and the average value of the ten-point average roughness (Rz) was defined as the surface roughness.
<Hardness>
In accordance with JIS K6253, using a durometer A, a 10 mm thick bulk was formed and evaluated.

Example 1
(1) Film formation of the 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 until completely dissolved. It was. 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 17000, 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 with a ball mill. This master batch solution had a solid content 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, and it inject | poured in the rotating drum, and shape | molded on the following conditions.

  Rotating drum: An internal mirror-finished metal drum having an inner diameter of 301.5 mm and a width of 540 mm was placed on two rotating rollers and arranged to rotate with the rotation of the rollers. For example, see FIG.

  Heating temperature: A far-infrared heater was disposed on the outer surface of the drum so that the inner surface temperature of the drum was controlled at 120 ° C.

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

After completion of the rotation and heating, the rotating drum was removed as it was without cooling, and was left in a hot-air residence 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 drum inner surface. The belt had a thickness of 80 μm, an outer peripheral length of 944.3 mm, a surface resistivity of 12.85 (logΩ / □), and a volume resistivity of 10.68 (LogΩ · cm).
(2) Surface layer deposition
30 g of PVDF resin (KF polymer # 850, manufactured by Kureha Corporation) was dissolved in a mixed solvent of 270 g of N, N-dimethylacetamide (DMAc) and 300 g of methyl ethyl ketone (MEK) to prepare a solution having a solid content concentration of 5 w%.

  And 58g was extract | collected from this solution, and it inject | poured in the rotating drum, and shape | molded on the following conditions.

  Rotating drum: A metal drum having an inner diameter of 301.0 mm and a width of 540 mm was placed on two rotating rollers and arranged to rotate with the rotation of the rollers. For example, see FIG.

  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 rate of 2 ° C./min up to 130 ° C., and heating was continued for 20 minutes while maintaining the rotation. After forming a surface layer on the drum inner surface, the drum was cooled to room temperature. The thickness of the surface layer formed on the inner surface of the drum was measured with an eddy current thickness gauge and found to be 3 μm.

As a preliminary test, when the electric resistance value of the surface layer single film prepared by the same method was measured, the surface resistivity was 9 × 10 ¹⁴ Ω / □, and the volume resistivity was 7 × 10 ¹³ Ω · cm.
(3) Formation of elastic layer Acidic carbon (pH 3.5) in a solution obtained by dissolving 1000 g of polyurethane elastomer (Ure Hyper RUP, manufactured by Dainippon Ink & Chemicals, Inc.) having a volume resistivity of 10 ¹³ Ω · cm in 1250 g of toluene 250 g was added and uniformly dispersed by a ball mill to prepare a master batch solution having a solid content of 50% by weight and a carbon black (CB) concentration of 20% by weight in the solid content. To 204 g of this master batch, 2.41 g of the curing agent CLH-1 and 3.26 g of CLH-5 (both curing agents are manufactured by Dainippon Ink & Chemicals, Inc.) were added and stirred.

  In a state where the solution was rotated on the inner surface of the surface layer formed in advance, the solution was uniformly applied in an amount to finally become an elastic layer having a thickness of 200 μm, and heating was started. Heating was carried out at 2 ° C./min up to 130 ° C., and heating was continued for 30 minutes at that temperature to form an elastic layer on the drum inner surface.

  The belt formed by forming an elastic layer inside the surface layer had a thickness of 205 μm, an outer peripheral length of 945.1 mm, a surface resistivity of 12.65 (logΩ / □), and a volume resistivity of 11.13 (LogΩ · cm). .

As a preliminary test, the rubber hardness of a urethane rubber single film prepared with this urethane rubber masterbatch solution was measured and found to be 63 ° with Type A (JIS K6253).
(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) having a thin coating on the outer surface (Takelac A-969 manufactured by Mitsui Chemicals Polyurethane Co., Ltd.) was inserted and overlapped. Next, heating (80 to 100 ° C.) was performed in a state where the substrate was pressure-bonded from the inner surface of the substrate to complete the bonding. The laminated multilayer belt was peeled off 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 284 μm, an outer peripheral length of 945.0 mm, a surface resistivity of 12.49 (logΩ / □), and a volume resistivity of 11.67 (LogΩ · cm).

Example 2
A multilayer belt was prepared in the same manner as in Example 1 except that the CB concentration in the solid content of Example 1 (1) was 19.5 wt% and the CB concentration in the raw material solid content of (3) was 17 wt%. .

Example 3
Only Example 1 (3) was produced by the following method. That is,
(3) Formation of elastic layer Lithium salt concentration of 30% by weight in a solution of 1000 g of polyurethane elastomer (Ure Hyper RUP, manufactured by Dainippon Ink & Chemicals, Inc.) having a volume resistivity of 10 ¹³ Ω · cm dissolved in 1300 g of toluene 6.6 g of ionic conductive agent (Sanconol 30R, manufactured by Sanko Chemical Co., Ltd.) was added and stirred for 30 minutes with a stirrer to prepare a master batch solution having a lithium ion salt concentration of 0.2% by weight in the solid content. . To 204 g of this master batch, 2.41 g of the curing agent CLH-1 and 3.26 g of CLH-5 (both curing agents are manufactured by Dainippon Ink & Chemicals, Inc.) were added and stirred. Thereafter, a film was formed in the same procedure as in Example 1. Except for the above, a multilayer belt was produced in the same manner as in Example 1.

Comparative Example 1
A multilayer belt was produced in the same manner as in Example 1 except that the CB concentration in the raw material solid content of Example 1 (3) was 27% by weight.

Comparative Example 2
A multilayer belt was produced in the same manner as in Example 2 except that the CB concentration in the raw material solid content of Example 2 (3) was 27% by weight.

Comparative Example 3
A multilayer belt was prepared in the same manner as in Example 3 except that the lithium ion salt concentration in the solid content of the master batch solution in Example 3 (3) was 1.0% by weight.

  Table 1 shows the resistivity of each sample multilayer belt before bonding and the finished product.

  These belts were incorporated in an electrophotographic apparatus as intermediate transfer belts, and the degree of toner scattering was observed with a loupe in the image.

The resistance balance in the table corresponds to the image evaluation result, and the following results were shown.
◯: No toner scattering and good image with no missing dots. Δ: A slight charge-up was observed on the belt. The image omission was confirmed, but it was well within the allowable limit. X: Toner splattered and dot omission occurred. In Examples 1 to 3, the resistance balance between the first belt and the second belt was The toner was not scattered because it was good. On the other hand, in Comparative Examples 1 to 3, toner scattering was observed. It was speculated that this was due to a problem in the resistance balance between the first belt and the second belt, and the volume resistivity was higher than the surface resistivity of the completed intermediate transfer belt. Further, in the comparative example, there was occurrence of dot omission thought to be due to insufficient toner carrying ability of the belt.

  As a result of the visual observation of the image, the high-definition image unique to the belt provided with rubber elasticity could be realized in the examples, but in the comparative example, the image quality was clearly inferior to that. .

  As described above, in the multilayer elastic belt of this example, the resistivity of each layer could be individually controlled, so that a balance between surface resistivity and volume resistivity suitable for a transfer belt could be established. As a result, when assembled in an electrophotographic apparatus, the transfer belt was free from problems such as scattering of a toner image carried on the surface, transfer failure due to insufficient carrying force, and charge-up of the belt surface. Therefore, it was proved that it can be suitably used as an intermediate transfer belt or the like.

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

Claims (10)

A first belt consisting of at least two layers of a surface layer containing a releasable material and an elastic layer containing an elastic rubber material and a second belt consisting of a base material layer containing a high-strength resin material are manufactured separately, A multilayer elastic belt for an electrophotographic apparatus, comprising an elastic layer side of one belt and a second belt bonded together,
The common logarithm value V ₁ of the volume resistivity (Ω · cm) of the first belt at 100 ° C. applied at 23 ° C. and 55% RH, and the volume resistivity at the time of 100 V application of the second belt at 23 ° C. and 55% RH ( A multilayer elastic belt for an electrophotographic apparatus, wherein a common logarithmic value V ₂ of Ω · cm) satisfies V ₁ > V ₂ . The common logarithm of the surface resistivity (Ω / □) of the first belt at 100 ° C. applied at 23 ° C. and 55% RH is the surface resistance of the second belt at 100 V applied at S ₁ , 23 ° C. and 55% RH. _{2. The} multilayer elastic belt for an electrophotographic apparatus according to claim 1, wherein S ₁ > V ₁ , S ₂ > V ₂ , and S ₁ <S ₂ when the common logarithm of the rate (Ω / □) is S _2. . 3. The multilayer elastic belt for an electrophotographic apparatus according to claim 1, wherein the elastic layer is a layer containing a polyurethane elastomer having an insulating property of a volume resistivity of 10 ¹³ Ω · cm or more and carbon black. 3. The multilayer elastic belt for an electrophotographic apparatus according to claim 1, wherein the elastic layer is a layer containing a polyurethane elastomer having an insulating property with a volume resistivity of 10 ¹³ Ω · cm or more and a lithium salt. 3. The multilayer elastic layer for an electrophotographic apparatus according to claim 1, wherein the surface layer is a layer containing a fluororesin material having an insulating property with a volume resistivity of 10 ¹³ Ω · cm or more and has a thickness of 5 μm or less. belt. Surface resistivity of the multilayer elastic belt for an electrophotographic apparatus at 100 V applied at 23 ° C. and 55% RH when V ₁ and V ₂ are in the range of 7 ≦ V ₁ ≦ 13, 4 ≦ V ₂ ≦ 12.5 3. The electrophotographic apparatus according to claim 1, wherein the common logarithm value of (Ω / □) is S ₁₂ and the common logarithm value of volume resistivity (Ω · cm) is V ₁₂ , wherein S ₁₂ > V ₁₂ is satisfied. For multilayer elastic belt. The multilayer elastic belt for an electrophotographic apparatus according to claim 1, wherein a shape of the multilayer elastic belt for an electrophotographic apparatus is endless. The multilayer elastic belt for an electrophotographic apparatus according to claim 1, wherein the material of the base material layer is polyimide or polyamideimide. A method for producing a multilayer elastic belt for an electrophotographic apparatus,
(1) A first belt consisting of at least two layers of a surface layer containing a releasable material and an elastic layer containing an elastic rubber material and a second belt consisting of a base material layer containing a high-strength resin material are manufactured separately. Process,
(2) Common logarithmic value V ₁ of volume resistivity (Ω · cm) when applying 100V of the first belt at 23 ° C. and 55% RH, and applying 100V of the second belt at 23 ° C. and 55% RH A step of measuring a common logarithm value V ₂ of the volume resistivity (Ω · cm) and confirming that V ₁ > V ₂ , and (3) an elastic layer side of the first belt and a second belt A manufacturing method comprising a step of manufacturing a multilayer elastic belt for an electrophotographic apparatus by bonding. Further, in the step (2), the common logarithmic value S ₁ of the surface resistivity (Ω / □) when 100 V of the first belt is applied at 23 ° C. and 55% RH, and the _first log at 23 ° C. and 55% RH. surface resistivity when 100V is applied for 2 belts common logarithm _{S 2} of (Ω / □) was _{measured, S 1> V 1, S} 2> V 2, S 1 < step of confirming that the _{S 2,} A method for producing a multilayer elastic belt for an electrophotographic apparatus according to claim 9.

Images