JP5153240B2 - Multilayer elastic belt used in image forming apparatus - Google Patents

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, which is 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, 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. In other words, since toner release is required to transfer toner from the surface of the intermediate transfer belt to a medium such as paper, surface energy such as fluororubber, silicone rubber, and fluororesin material can be used for the members constituting the surface layer. By using a small material, toner can be easily released from the surface of the intermediate transfer belt, and it has been successfully used to improve transfer efficiency.

  However, when the surface of the intermediate transfer belt is formed of a rubber elastic body made of fluorine rubber or silicone rubber, the toner releasability is not always sufficient due to the adhesiveness of the rubber, and the toner formed on the surface of the intermediate transfer belt There is a problem that the toner in the lowermost layer of the image is not transferred to a medium such as paper and remains on the surface of the intermediate transfer belt. That is, the efficiency of secondary transfer is reduced. In addition, when a cleaning blade made of silicone rubber or urethane rubber is used in the cleaning process to remove the toner remaining on the surface of the intermediate transfer belt, the surface of the intermediate transfer belt is sticky, which In the worst case, the blade will be damaged.

  Furthermore, in an image forming apparatus, it is common to detect the image density and position on the intermediate transfer belt using a light reflection sensor. However, if the surface layer is formed of a rubber elastic body, the glossiness is low, so light absorption is achieved. The detection accuracy of the sensor is reduced.

  Patent Document 4 describes a configuration having a surface layer made of a fluororesin such as FEP on an elastic layer.

  However, the surface layer has good releasability, cleanability, and glossiness, and it has been found that such a fluororesin is very preferable as the material of the surface layer. Since it is stiffer than the body layer, the flexibility of the elastically imparted intermediate transfer belt is lowered, and the stable formation of the transfer region is hindered. As a result, image defects such as voids occur as in the case of conventional resin belts. To solve this problem, the thickness of the fluororesin surface layer may be made extremely thin. However, the thin and hard surface layer cannot follow the elongation of the elastic layer when the intermediate transfer belt is curved, and a large number of fine surfaces on the surface. Cracks occur and cause image defects.

  On the other hand, dimensional accuracy is very important in the function of the intermediate transfer belt, and if there are variations in circumference or thickness, problems such as image displacement occur. The most general manufacturing method of the intermediate transfer belt is to spray coat an elastic layer and a surface layer in this order on the surface of a high-strength base material layer such as polyimide obtained by centrifugal molding. However, in this method, the film thickness of each layer is not necessarily uniform due to variations in coating amount, clogging of spray nozzles, air mixing conditions, and the like. As a result, the thickness accuracy is deteriorated.

  In order to avoid this, there is a method of manufacturing a transfer belt by forming each layer according to a mold regulation by a method called rotational molding or centrifugal molding. That is, a production method is adopted in which a surface layer is formed on the inner surface of the mold and an elastic layer is formed on the inner side. As a result, an intermediate transfer belt having a high circumferential length and thickness accuracy can be obtained.

  By the way, Patent Document 5 has an example of using a water-based fluororubber paint, and in addition, generally for forming a water-based surface layer film in a urethane resin in which a fluororesin is dispersed, an acrylic resin in which a fluororesin is dispersed, or the like. There are paints, but since these are water-based, the liquid of the material is repelled on the inner surface of the mold when forming the surface layer, and a large number of holes are opened in the repelled part when trying to make a thickness of 10 μm or less Therefore, it does not become a film. In order to improve the wettability of the inner surface of the mold, a method such as removing the mold release agent on the inner surface of the mold is also considered as a countermeasure, but there is a problem that it cannot be removed from the mold after film formation.

Further, in the application of the surface layer by spray coating as in the example of Patent Document 5, the traces of liquid droplets at the time of spraying remain on the surface, which becomes uneven and the surface accuracy represented by the surface roughness is satisfactory. It is not a thing.
Japanese Patent No. 3248455 Japanese Patent Laid-Open No. 2001-282009 JP 2002-292655 A Japanese Patent No. 3019781 Japanese Patent Laid-Open No. 11-212374

  As described above, the conventional technique has the flexibility of the surface layer, that is, the property that does not hinder the softness of the elastic layer and the following property that does not generate cracks, and further satisfies all the property requirements of glossiness and releasability. Is difficult. Furthermore, in the production of the surface layer, it is difficult to obtain film thickness accuracy and surface accuracy when a water-based paint is used or when spray coating is used.

  An object of the present invention is to provide a multilayer elastic belt having a surface layer having good elasticity, releasability, glossiness, film thickness accuracy, surface accuracy, etc., and excellent transfer efficiency.

  As a result of earnest research to solve the above-mentioned problems, the present inventor is a multilayer elastic belt composed of at least three layers of a surface layer, an elastic layer, and a base material layer, and the surface layer is formed by centrifugal molding. A multilayer elastic belt having a surface layer containing fluororubber and vinylidene fluoride resin is required as an intermediate transfer belt, elasticity in the thickness direction, toner releasability, glossiness, dimensional accuracy, etc. Has been found to have a good balance.

In general, the intermediate transfer belt is considered to have good semiconductivity in each of the base material layer, the elastic layer, and the surface layer in order to electrically transfer the toner. It has been 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.

  Based on this knowledge, further studies have been made and the present invention has been completed.

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

  Item 1. A multilayer elastic belt comprising at least three layers of a surface layer, an elastic layer, and a base material layer, the surface layer containing fluororubber and vinylidene fluoride resin, and an organic solvent-based blend containing the fluororubber and vinylidene fluoride resin A multilayer elastic belt that is a layer obtained by centrifugal molding of a material.

  Item 2. Item 10. The multilayer elastic belt according to Item 1, wherein the weight ratio of the fluororubber and the vinylidene fluoride resin contained in the surface layer is in the range of 40:60 to 5:95.

Item 3. Item 3. The multilayer elastic belt according to Item 1 or 2, wherein the surface layer has a volume resistivity of 10 ¹² Ω · cm or more.

  Item 4. Item 4. The multilayer elastic belt according to any one of Items 1 to 3, wherein the multilayer elastic belt has an endless shape.

Item 5. Item 5. The multilayer elastic belt according to any one of Items 1 to 4, wherein the multilayer elastic belt is semiconductive having a volume resistivity of 10 ⁶ Ω · cm to 10 ¹³ Ω · cm.

  Item 6. Item 6. The multilayer elastic belt according to any one of Items 1 to 5, wherein the base material layer has a Young's modulus of 1000 MPa or more.

  Item 7. Item 7. The multilayer elastic belt according to any one of Items 1 to 6, wherein the elastic layer is made of a cured product of liquid urethane rubber.

  Item 8. Item 8. An electrophotographic belt comprising the multilayer elastic belt according to any one of items 1 to 7.

Item 9. A method for producing a multilayer elastic belt comprising at least three layers of a surface layer, an elastic layer and a base material layer,
(1) A step of forming a base material layer by centrifugal molding of the base material material,
(2) A step of forming a surface layer by centrifugally molding an organic solvent-based blend material containing fluororubber and vinylidene fluoride resin,
(3) A step of forming an elastic layer by centrifugally molding an elastic layer material on the inner surface of the surface layer formed in (2) above, and (4) of the base material layer formed in (1) above A process of superposing and bonding both the outer surface and the inner surface of the two-layer film made of the surface layer and the elastic layer formed in (3) above,
The manufacturing method characterized by including.

  The multilayer elastic belt of the present invention has not only a fluororesin but also a fluororubber component in the surface layer, so that the flexibility of the surface layer, that is, the property that does not hinder the softness of the elastic layer and the follow-up property that does not generate cracks. . Furthermore, it is possible to satisfy the glossiness and releasability property requirements that could not be obtained with a surface layer of only fluororubber. Since a solvent-based paint is used in production, a surface layer can be formed on a mold, and film thickness accuracy and surface accuracy can be obtained.

Hereinafter, the present invention will be described in detail.
I. Formation of surface layer The surface layer of the present invention comprises a blend material of fluororubber and vinylidene fluoride resin. This surface layer effectively functions as a release layer from which toner can be easily released.

  Examples of fluororubbers include vinylidene fluoride (FKM), tetrafluoroethylene-propylene (FEPM), tetrafluoroethylene-purple chlorovinyl ether (FFKM), etc. It is also preferable from the viewpoint of availability.

  The vinylidene fluoride resin may be a homopolymer (PVdF resin) or a copolymer of vinylidene fluoride and hexafluoropropylene (VDF-HFP resin).

  Fluoro rubber and vinylidene fluoride resin are dissolved in an organic solvent to obtain a blend material. This blend material is formed into a surface layer by centrifugal molding using a mold described later. Examples of the organic solvent include ester solvents such as ethyl acetate and butyl acetate; ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone.

  Specifically, after adding a curing agent to fluorine rubber such as FKM, it is dissolved in an ester solvent such as ethyl acetate or butyl acetate, and a solid content of 5 to 20% by weight (preferably 5 to 10% by weight) is obtained. To prepare. Also, vinylidene fluoride resin such as PVdF is dissolved in a ketone solvent such as methyl ethyl ketone and methyl isobutyl ketone, and this is also adjusted to a solid content of 5 to 20% by weight (preferably 5 to 10% by weight). A material solution for the surface layer is prepared by mixing.

  The surface layer solution is applied to the inner surface of the cylindrical mold, and heated by centrifugal molding while rotating the mold with a rotary molding machine to obtain a cured surface layer by volatilizing the solvent.

  The thickness of the surface layer can be calculated in advance from the input amount of the material solution, and is preferably 15 μm or less, more preferably 1 to 10 μm, and particularly preferably 1 to 7 μm.

  By doing so, a thin film that does not impair the elasticity of the elastic layer can be obtained. Normally, water-based paints repel paint when a thin film of 15 μm or less is formed by a silicone-type or fluorine-type release agent applied to the inner surface of the mold. Since it does not repel on the inner surface of the mold, it can be formed to a thin film of 1 to 2 μm.

  The mixing ratio of fluororubber and vinylidene fluoride resin is arbitrary, but too little fluororubber will harden the surface layer and offset the softness of the elastic layer, conversely if too little vinylidene fluoride resin , Surface gloss and friction coefficient will decrease. Therefore, it is preferable to select the mixing ratio of the fluororubber and the vinylidene fluoride resin in the material component for forming the surface release layer so that these balances can be achieved. Specifically, the weight ratio between the fluororubber and the vinylidene fluoride resin is in the range of 40/60 to 5/95, preferably in the range of 30/70 to 10/90, more preferably in the range of 25/75 to 15/85. It is a range.

The surface layer does not necessarily require semiconductivity, but the volume resistivity is 10 ¹² Ω · cm or more, preferably 10 ¹² to 10 ¹⁴ Ω · cm, for forming a good image. When the volume resistivity is less than 10 ¹² Ω · cm, the bias charge travels through the surface layer and escapes in the surface direction, resulting in loss of charge to be applied in the thickness direction necessary for image formation, resulting in an image defect. .

  In order to obtain the above volume resistivity, it can be adjusted using a conductive agent as necessary. Examples of the conductive agent include carbon black such as acetylene black and ketjen black. The blending amount of the conductive agent may be 30 parts by weight or less, preferably 5 to 20 parts by weight with respect to 100 parts by weight of the total of the fluororubber and the vinylidene fluoride resin.

  Centrifugal molding of the surface layer can be performed as follows using, for example, a cylindrical mold and a rotary molding machine. After injecting the liquid raw material in an amount equivalent to obtaining the final thickness into the stopped cylindrical mold, gradually increase the rotational speed to the speed at which centrifugal force works, and evenly on the entire inner surface with centrifugal force Cast.

  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.

The rubber hardness of the blend material of fluororubber and vinylidene fluoride resin constituting the surface layer may be about 70 to 95 degrees in terms of type A hardness (JIS K6253).
II Formation of Elastic Layer The elastic layer in the multilayer elastic belt of the present invention is made of a cured product of liquid urethane rubber. For example, a liquid urethane rubber, and if necessary, an elastic layer material containing 5 to 40 parts by weight of carbon black with respect to 100 parts by weight of the liquid urethane rubber is applied and cured on the inner surface of the surface layer obtained in I above. Is done.

  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.

  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.

By adding carbon black to the insulating urethane rubber in this way, the elastic layer has a semi-conductivity of about 10 ⁸ to 10 ¹³ Ω · cm (preferably about 10 ⁹ to 10 ¹² Ω · cm). Thus, 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.

In addition, depending on the volume resistivity of the belt to be obtained, various ionic conductive agents as fillers (for example, perchlorates such as tetraethylammonium and tetrabutylammonium, alkali metal chlorates such as lithium, sodium and calcium) The volume resistivity of the liquid urethane rubber before addition of carbon black can be made to be a low resistance material of 10 ⁹ Ω · cm or less. Specific examples of the ionic conductive agent include PEL-100 manufactured by Nippon Carlit Co., Ltd. When adding an ionic conductive agent, 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 elastic layer material containing a cured liquid urethane material having an adjusted resistance and carbon black as required is placed on the inner surface of the surface layer formed on the inner side of the mold, and is subjected to centrifugal molding. 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.

The volume resistivity of the elastic layer is usually about 10 ⁸ 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, considering 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 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, a conductive agent such as carbon black described above is added to the polyamic acid so as to be about 5 to 25 parts by weight with respect to 100 parts by weight of the base material layer resin as necessary. It may be added to the solution. 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 by centrifugal molding is different from the cylindrical mold used for forming the surface layer, the fluororubber layer, and the rubber elastic layer from the viewpoint of shrinkage rate of raw materials and heat-resistant temperature. It is preferable to use a metal layer-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 volume resistivity of the base material layer is usually about 10 ⁸ 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 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.

As described above, a base material layer having a seamless high strength can be obtained.
IV Formation of multilayer elastic belt (three layers)
Finally, the layers separately formed by centrifugal molding in the above I and III, that is, the integrated surface layer and elastic layer, and the base material layer, the inner surface of the elastic layer and the base material layer Overlap so that the outer surface is in contact. You may apply | coat an adhesive agent and a primer between both layers as needed. After the two layers are superposed, it is preferable that the space between the two layers be in a sealed state. 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.

  Specific examples of the three-layer process will be given. A laminate adhesive is uniformly applied to the inner surface of the two-layer film (the inner surface of the elastic layer) formed of the base material layer and the elastic rubber layer formed on 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 and air-dried. Then, the primer is superimposed on the inner surface of the elastic layer, and an inner mold that is in close contact with the inner surface of the base material layer is inserted so as not to shift its position.

  Thereafter, heat treatment is performed at about 130 ° C. for about 40 to 60 minutes, and the 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.

  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 volume resistivity of the multilayer elastic belt of the present invention can be made semiconductive with 10 ⁶ Ω · cm or more and 10 ¹³ Ω · cm or less.

  As described above, the multilayer elastic belt of the present invention is suitably used as an electrophotographic belt such as a developing sleeve, an intermediate transfer belt, a transfer conveyance belt, a fixing 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 defined as Bg. 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 made Ag. The solid content concentration is represented by the following formula (II).

Elastic layer solid content concentration = B / A 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.
<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 resistivity, volume resistivity>
The surface resistivity (Ω / □) and the volume resistivity (Ω · cm) were measured using a resistance measuring instrument “HIRESTA IP / HR Blob” manufactured by Mitsubishi Chemical Corporation. 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 indicated by the average value.
<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.

Transfer efficiency (%) = 100 × [(toner weight before transfer) − (toner weight after transfer)] / (toner weight before transfer)
Each transfer efficiency was evaluated according to the following criteria.

Primary transfer efficiency: 98% or more “○”, 95-98% “△”, 95% or less “×”
Secondary transfer efficiency: 95% or more “○”, 90-95% “△”, 90% or less “×”
○ means excellent, Δ means usable, × means inferior, unusable.
<Line dropout>
Line dropout (primary transfer efficiency) was determined from the above transfer efficiency equation by measuring the weight of toner on the photoreceptor before and after transfer in an image of only a line image.

  Line breakage was evaluated according to the following criteria.

Line omission: 90% or more “○”, 85-90% “△”, 85% or less “×”
○ means excellent, Δ means usable, × means inferior, unusable.
<Measurement of glossiness>
Measured value when using Nippon Denshoku Industries Co., Ltd. gloss meter PG-1M and setting the incident angle to 20 °. The average value of 3 points in the circumferential direction was used.
<Measurement of Young's modulus>
The Young's modulus of the base material layer was measured in accordance with JIS K7127 at a test speed of 20 mm / min using a 25 x 250 mm strip test piece.

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 2 × 10 ¹¹ to 4 × 10 ¹¹ Ω / □, and a volume resistivity of 1 × 10 ^{9 to} 3 × 10 ⁹ Ω · cm.
(2) Film formation of the surface layer Solvent-based fluororubber paint (DPS-231RD manufactured by Daikin Industries, Ltd.) 100g (inner rubber solid content is 33g) diluted with 560g of methyl ethyl ketone (MEK) solution with a solid content concentration of 5% by weight Was made. 30 g of PVDF resin (KF polymer # 850, manufactured by Kureha Co., Ltd.) 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%.

  These raw materials were mixed with 20 g of a fluororubber solution and 80 g of a PVDF resin solution to obtain 100 g of a blend raw material, and a film was formed under 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 6 μm.

As a preliminary test, the electrical resistance value of the fluororubber and PVDF mixed material layer single film prepared by the same method was measured. The surface resistance value was 5 × 10 ¹⁴ Ω / □, and the volume resistivity was 2 × 10 ¹³ Ω · cm. It was.
(3) Film formation of elastic layer Add 300 g of acidic carbon (pH 3.5) to a solution of 1000 g of polyurethane elastomer (Ure Hyper RUP1627, manufactured by Dainippon Ink and Chemicals) in 1300 g of toluene, and uniformly disperse with a ball mill. And a master batch solution having a solid concentration of 50% by weight and a carbon black (CB) concentration in the solid content of 23% by weight was prepared. To 204 g of this master batch, 2.41 g of the curing agent CLH-1 and 3.26 g of CLH-5 (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 performed at 2 ° C./min up to 150 ° C., and heating was continued for 30 minutes at that temperature to form an elastic layer on the drum inner surface.

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) Laminating the inner surface of the elastic layer and the outer surface of the 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, The polyimide belt (base material layer) (1) thinly applied on the outer surface was inserted and overlapped. Next, it heated (80-100 degreeC) in the state crimped | bonded from the inner surface of the base material, and the lamination was completed. 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 has a thickness of 284 μm, an outer peripheral length of 945.0 mm, a surface resistivity of 7 × 10 ^{11 to} 9 × 10 ¹¹ Ω / □, a volume resistivity of 6 × 10 ^{10 to} 9 × 10 ¹⁰ Ω · cm, a surface static friction coefficient of 0.37, The glossiness was 51.

Example 2
A multilayer belt was produced in the same manner as in Example 1 except that 40 g of fluororubber solution and 60 g of PVDF resin solution were mixed as the surface layer of Example 1 (2).

Example 3
A multilayer belt was prepared in the same manner as in Example 1, except that 5 g of the fluororubber solution and 95 g of the PVDF resin solution were mixed as the surface layer of Example 1 (2).

Example 4
A multilayer belt was produced in the same manner as in Example 1 except that 30 g of the fluororubber solution and 70 g of the PVDF resin solution were mixed as the surface layer of Example 1 (2).

Comparative Example 1
A multilayer belt was produced in the same manner as in Example 1 except that the surface layer of Example 1 (2) was produced with 100 g of a fluororubber solution.

Comparative Example 2
A multilayer belt was prepared in the same manner as in Example 1 except that 100 g of PVDF resin solution was used as the surface layer of Example 1 (2).

Comparative Example 3
A multilayer belt was produced in the same manner as in Example 1 except that 50 g of the fluororubber solution and 50 g of the PVDF resin solution were mixed as the surface layer of Example 1 (2).

  Table 1 shows the actual machine evaluation results of each sample multilayer belt.

  3 and 4 show the correlation between the coefficient of static friction and the PVdF content in the surface layer material solid content, and the glossiness and the PVdF content in the surface layer material solid content in the examples and comparative examples, respectively.

  From Table 1, FIG. 3, and FIG. 4, the friction coefficient is preferably 0.5 or less from the viewpoint that the toner release is not impaired. Above that, toner is not transferred to a medium such as paper during the secondary transfer due to the adhesiveness of the belt surface, and a part of the toner remains on the belt surface. Further, it is desirable that the glossiness exceeds 40. Depending on the type of position detection sensor, position sensing is often impossible at 40 or less.

  From Table 1, it can be seen that the belt of this embodiment has a gloss level that can activate the position detection sensor, has extremely high primary and secondary transfer efficiencies, and has almost no missing line. Therefore, 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. It is a graph which shows the relationship between the PVdF content ratio in the surface layer material solid content in the belt of an Example and a comparative example, and the static friction coefficient of the obtained belt surface. It is a graph which shows the relationship between the PVdF content ratio in surface layer material solid content, and the glossiness of the obtained belt surface in an Example and a comparative example.

Claims (9)

  A multilayer elastic belt comprising at least three layers of a surface layer, an elastic layer, and a base material layer, the surface layer containing fluororubber and vinylidene fluoride resin, and an organic solvent-based blend containing the fluororubber and vinylidene fluoride resin A multilayer elastic belt that is a layer obtained by centrifugal molding of a material.   The multilayer elastic belt according to claim 1, wherein the weight ratio of the fluororubber and the vinylidene fluoride resin contained in the surface layer is in the range of 40/60 to 5/95. The multilayer elastic belt according to claim 1, wherein the surface layer has a volume resistivity of 10 ¹² Ω · cm or more.   The multilayer elastic belt according to claim 1, wherein the multilayer elastic belt has an endless shape. The multilayer elastic belt according to any one of claims 1 to 4, wherein the multilayer elastic belt is semiconductive having a volume resistivity of 10 ⁶ Ω · cm to 10 ¹³ Ω · cm.   The multilayer elastic belt according to claim 1, wherein the base material layer has a Young's modulus of 1000 MPa or more.   The multilayer elastic belt according to any one of claims 1 to 6, wherein the elastic layer is made of a cured product of liquid urethane rubber.   An electrophotographic belt comprising the multilayer elastic belt according to claim 1. A method for producing a multilayer elastic belt comprising at least three layers of a surface layer, an elastic layer and a base material layer,
(1) A step of forming a base material layer by centrifugal molding of the base material material,
(2) A step of forming a surface layer by centrifugally molding an organic solvent-based blend material containing fluororubber and vinylidene fluoride resin,
(3) A step of forming an elastic layer by centrifugally molding an elastic layer material on the inner surface of the surface layer formed in (2) above, and (4) of the base material layer formed in (1) above A process of superposing and bonding both the outer surface and the inner surface of the two-layer film made of the surface layer and the elastic layer formed in (3) above,
The manufacturing method characterized by including.

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