JP5570099B2 - Seamless belt - Google Patents

Description

  The present invention relates to a multilayer seamless belt having different conductive material contents.

  In recent years, fixing belts, transfer conveyance belts, intermediate transfer belts, transfer fixing belts, and photoreceptor belts used in various image forming apparatuses have been required to have high speed and high image quality. Is desired.

  As a material for the seamless belt, polyimide is usually used because of its excellent mechanical properties and heat resistance. For a seamless belt mainly composed of polyimide, for example, a polyamic acid solution (polyimide resin precursor) in which polyamic acid and a conductive material are dissolved (or dispersed) in a solvent is prepared, and this solution is used as a cylindrical mold. After being applied to the inner surface of the film, it is obtained by drying and curing.

  When the above-described seamless belt mainly composed of polyimide is used as a transfer belt, if the surface resistivity (ρs) of the inner surface of the transfer belt is increased, the flow of the transfer current on the inner surface is hindered. descend. In order to prevent this, if the conductive material in the transfer belt is increased, the volume resistivity (ρv) of the entire transfer belt is lowered, so that the charge amount of the transfer belt is attenuated and toner fixing failure occurs, and printing failure ( So-called white spots occur.

  In order to solve the above-described problem, Patent Document 1 and Patent Document 2 below propose a two-layer seamless belt including an inner layer having a high conductive material content and an outer layer having a low conductive material content. In these belts, ρs on the belt inner surface can be lowered and ρv of the entire belt can be raised.

JP 07-156287 A JP 2001-0334075 A

  However, in the conventional two-layer seamless belt, when the content of the conductive material in the inner layer of the belt is increased for the purpose of improving the transfer efficiency, the inner layer becomes brittle and there is a problem in durability. Further, in the conventional method for producing a two-layer seamless belt, it is not possible to increase the thickness of only the belt inner layer. That is, as described in Patent Document 1 and the like, the conventional two-layer seamless belt manufacturing method applies an outer layer forming polyamic acid solution to the inner surface of a cylindrical mold, Since the inner layer forming polyamic acid solution is applied and formed, it is difficult to control the thickness of each layer. Therefore, in the conventional two-layer seamless belt manufacturing method, in order to improve the transfer efficiency, prevent white spots from occurring and improve the durability, the entire belt must be thickened. It was difficult to ensure the required flexibility.

  The present invention provides a seamless belt that can improve transfer efficiency and prevent white spots from occurring and has high durability and flexibility.

The seamless belt of the present invention is a seamless belt having a first layer containing a polyimide resin and a conductive material, and a second layer covering the outer periphery of the first layer and containing a polyimide resin and a conductive material. When the content of the conductive material with respect to 100 parts by weight of the polyimide resin is W ₁ part by weight and the content of the conductive material with respect to 100 parts by weight of the polyimide resin in the second layer is W ₂ parts by weight, W ₁ / W ₂ The value is 1.10 to 1.40, and the thickness of the first layer is larger than the thickness of the second layer.

According to the seamless belt of the present invention, by setting the value of W ₁ / W ₂ to 1.10 to 1.40, the content of the conductive material in the first layer that is the inner layer is the first value that is the outer layer. It becomes higher than the content of the conductive material in the two layers. Thereby, ρs on the belt inner surface can be lowered and ρv of the entire belt can be increased, so that transfer efficiency can be improved and white spots can be prevented from occurring. Further, since the thickness of the first layer (inner layer) is thicker than the thickness of the second layer (outer layer), a belt having high durability can be obtained even if the content of the conductive material in the inner layer is increased. Even if the thickness of the inner layer is increased, an increase in the thickness of the entire belt can be suppressed by reducing the thickness of the outer layer, so that a highly flexible belt can be obtained.

  In the seamless belt of the present invention, the content of the conductive material with respect to 100 parts by weight of the polyimide resin in the first layer is 21 to 25 parts by weight, and the content of the conductive material with respect to 100 parts by weight of the polyimide resin in the second layer is 17 to 21 parts by weight is preferable. Within this range, ρs on the inner surface of the belt and ρv on the entire belt can be easily controlled within appropriate ranges, so that transfer efficiency can be further improved and white spots can be more reliably prevented.

In the seamless belt of the present invention, when the thickness of the first layer is T ₁ μm and the thickness of the second layer is T ₂ μm, the value of T ₁ / T ₂ is 1.6 to 7.0. Preferably there is. Within this range, durability and flexibility can be further improved.

  In the seamless belt of the present invention, it is preferable that the thickness of the first layer is 50 to 75 μm and the thickness of the second layer is 5 to 30 μm. Within this range, a belt having an excellent balance between durability and flexibility can be obtained.

  In the present invention, the conductive material contained in the first and second layers is preferably carbon black. This is because it can be easily obtained and can be uniformly dispersed in a solvent.

  Hereinafter, embodiments of the present invention will be described.

The present invention is a seamless belt having a cylindrical first layer disposed inside and a cylindrical second layer covering the outer periphery of the first layer, and the content of the conductive material in each layer is different. Intended for seamless belts. In the seamless belt of the present invention, the content of the conductive material with respect to 100 parts by weight of the polyimide resin in the first layer is W ₁ part by weight, and the content of the conductive material with respect to 100 parts by weight of the polyimide resin in the second layer is W ₂ parts by weight. when _the value of W 1 / _{W 2} is 1.10 to 1.40. Thereby, ρs on the belt inner surface can be lowered and ρv of the entire belt can be increased, so that transfer efficiency can be improved and white spots can be prevented from occurring. In the present invention, W ₁ / W ₂ is preferably in the range of 1.16 to 1.26 in order to further improve transfer efficiency and prevent white spots from occurring more reliably. The seamless belt of the present invention is not limited to a belt consisting only of the first layer and the second layer. As long as the effect of the present invention is obtained, for example, an intermediate layer may be interposed between the first layer and the second layer. Further, a protective layer may be provided outside the second layer.

In the seamless belt of the present invention, the W ₁ is preferably 21 to 25 and the W ₂ is preferably 17 to 21, more preferably the W ₁ is 22 to 24, and the W ₂ is 18 to 20. Within this range, ρs on the inner surface of the belt and ρv on the entire belt can be easily controlled within appropriate ranges, so that transfer efficiency can be further improved and white spots can be more reliably prevented.

  In the seamless belt of the present invention, ρs (log Ω / □) on the inner surface of the belt is preferably 10.5 to 11.5, and more preferably 10.8 to 11.2. Within this range, the transfer efficiency can be further improved. In the seamless belt of the present invention, ρv (log Ω · cm) of the entire belt is preferably 10.5 to 13.0, more preferably 10.8 to 12.6, and more preferably 11.0 to More preferably, it is 12.0. Within this range, white spots can be more reliably prevented. If ρv exceeds 13.0, an offset failure may occur during continuous printing. This offset failure is a phenomenon that occurs when the second sheet is printed in a charged state because the ρv is high, so that it is difficult to remove electricity after the first sheet is printed. This is a phenomenon in which two images are printed overlappingly under the influence of charging.

  For the seamless belt of the present invention, the ρs and ρv can be controlled by adjusting the content of the conductive material in each layer, for example, in order to make the ρs and ρv within the appropriate ranges. In addition, said (rho) s and (rho) v can be measured by the method as described in the Example mentioned later.

  In the seamless belt of the present invention, the thickness of the first layer is thicker than the thickness of the second layer. Thereby, even if the content of the conductive material of the first layer which is the inner layer is increased, a belt having high durability can be obtained. Even if the thickness of the inner layer is increased, an increase in the thickness of the entire belt can be suppressed by reducing the thickness of the outer layer, so that a highly flexible belt can be obtained.

In the seamless belt of the present invention, when the thickness of the first layer is T ₁ μm and the thickness of the second layer is T ₂ μm, the value of T ₁ / T ₂ is 1.6 to 7.0. Is preferable, it is more preferable that it is 1.8-6.8, and it is still more preferable that it is 2.5-5.5. This is because durability and flexibility can be further improved. In the seamless belt of the present invention, the thickness of the first layer is preferably 50 to 75 μm, the thickness of the second layer is preferably 5 to 30 μm, the thickness of the first layer is 60 to 70 μm, and the thickness of the second layer is More preferably, it is 10-20 micrometers. Within this range, a belt having an excellent balance between durability and flexibility can be obtained. Also, the smoothness of the belt surface can be ensured.

  Next, the suitable method for manufacturing the seamless belt of this invention is demonstrated.

  In this method, at least a polyamic acid solution for forming the first layer (hereinafter referred to as a first polyamic acid solution) and a polyamic acid solution for forming the second layer (hereinafter referred to as a second polyamic acid solution) Two types of polyamic acid solutions are used. Examples of the preparation method include a method of adding an acid dianhydride or a derivative thereof and a diamine to a dispersion of a conductive material in an approximately equimolar amount and reacting them in an organic solvent.

  Examples of suitable acid dianhydrides include pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic acid Dianhydride, 2,3,3 ′, 4-biphenyltetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride Anhydrides, 1,4,5,8-naphthalenetetracarboxylic dianhydride and the like can be mentioned.

  Examples of suitable diamines include 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, 3,3′-diaminodiphenylmethane, 3,3′-dichlorobenzidine, 4,4′-diaminodiphenyl sulfide, 3 , 3′-diaminodiphenylsulfone, 1,5-diaminonaphthalene, m-phenylenediamine, p-phenylenediamine, 3,3′-dimethyl-4,4′-biphenyldiamine, benzidine, 3,3′-dimethylbenzidine, 3,3′-dimethoxybenzidine, 4,4′-diaminodiphenylsulfone, 4,4′-diaminodiphenylpropane and the like can be mentioned.

  Examples of suitable organic solvents include acetone, chloroform, methyl ethyl ketone, tetrahydrofuran, dioxane, acetonitrile, alcohol solvents (methanol, ethanol, isopropanol, etc.), N, N-dimethylacetamide, dimethylformamide, N-methyl-2-pyrrolidone. (NMP) or the like can be used, but N, N-dimethylacetamide, NMP, and dimethylformamide, which are polar amide solvents, are preferable.

  As the conductive material used in the present method, various carbons such as carbon black, inorganic compounds such as aluminum, nickel, tin oxide and potassium titanate, conductive polymers such as polyaniline and polypyrrole, and the like can be used. In this case, in order to suppress variation in the surface resistance of the seamless belt, it is preferable to uniformly disperse the conductive material in the polyamic acid solution.

  The plural polyamic acid solutions used in this method can be appropriately selected in material composition according to the required performance. From the viewpoint of improving the thickness accuracy, the Brookfield viscometer at 25 ° C. It is preferable to adjust the concentration and the like of each material so that the viscosity measured by (B-type viscometer) is 200 to 1000 Pa · s.

  Hereinafter, specific embodiments of the method will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an example of a manufacturing apparatus used in this method. FIG. 2 is a schematic sectional view of an annular multilayer die used in the manufacturing apparatus of FIG.

  As shown in FIG. 1, the manufacturing apparatus 1 includes a control means 10, an annular multilayer die 20, a hydraulic cylinder mechanism 28, a cylindrical mold 30, supply machines 40 a and 40 b, hoppers 50 a and 50 b, a gas injection means 60, and a pneumatic cylinder. It has a mechanism 61, a compressor 70, and other components not shown. A specific manufacturing procedure by the manufacturing apparatus 1 will be described later. In the manufacturing apparatus 1, gas injection means is provided in the hollow portion of the multilayer cylindrical film 15 (see FIGS. 3A to 3C described later) extruded from the annular multilayer die 20. Since gas is injected using 60, the polyamic acid solution can be extruded while maintaining the cylindrical shape of the multilayered cylindrical film 15. Therefore, since the smoothness of the surface of the multilayer cylindrical film 15 can be ensured, the seamless belt 18 (see FIG. 3D described later) having a uniform thickness can be formed on the inner surface of the cylindrical mold 30. Thereby, the appearance defect of the seamless belt 18 can be reduced and the thickness accuracy can be improved.

  The control means 10 operates the feeders 40a and 40b based on the set values of the manufacturing conditions input by the user via an input means (not shown) such as a touch panel or buttons, or stored in advance in the memory. The operation of the annular multilayer die 20 in the vertical direction, the operation of the gas injection means 60, and the like are controlled. The control means 10 can be usually realized by a CPU, a memory or the like.

  As shown in FIG. 2, the annular multilayer die 20 includes a first flow path 21 through which the first polyamic acid solution 11 flows, a second flow path 22 through which the second polyamic acid solution 12 flows, An annular discharge port 23 communicating with the first and second flow paths 21 and 22 is formed. Each of the first and second flow paths 21 and 22 has an annular cut surface in a direction orthogonal to the flow direction, and the second flow path 22 is disposed on the outer peripheral side of the first flow path 21. Further, the cross-sectional area of the first flow path 21 is cut off from the flow path of the second flow path 22 so that the first layer 16 of the obtained seamless belt 18 is thicker than the second layer 17 (see FIG. 3D described later). It is larger than the area.

  The first polyamic acid solution 11 is supplied from the feeder 40 a (see FIG. 1) to the annular multilayer die 20 and flows through the first flow path 21. On the other hand, the second polyamic acid solution 12 is supplied from the feeder 40 b (see FIG. 1) to the annular multilayer die 20 and flows through the second flow path 22. Then, the first polyamic acid solution 11 and the second polyamic acid solution 12 merge at the connection portion 24 where the first flow path 21 and the second flow path 22 are connected, and are pushed out from the annular discharge port 23. Here, since the first and second polyamic acid solutions 11 and 12 are high in viscosity, the first and second polyamic acid solutions 11 and 12 are extruded from the annular discharge port 23 as a multilayered cylindrical film 15 having two layers without being compatible with each other. In addition, 1-20 mm is preferable and, as for the space | interval L of the annular discharge port 23 and the connection part 24, 1-10 mm is more preferable. Within this range, the thickness of each layer of the multilayer cylindrical film 15 can be prevented from varying due to the influence of the discharge pressure. Moreover, in this embodiment, although the flow-path cross-sectional area of the 1st and 2nd flow paths 21 and 22 is changed, the flow-path cross-sectional area of the 1st and 2nd flow paths 21 and 22 may be equivalent. . In that case, by making the discharge pressure of the 1st polyamic acid solution 11 larger than the discharge pressure of the 2nd polyamic acid solution 12, for example according to the thickness ratio of the 1st layer 16 and the 2nd layer 17 of the seamless belt 18 obtained. The discharge amount of each of the first and second polyamic acid solutions 11 and 12 may be adjusted.

The inner diameter D ₁ (see FIG. 1) of the cylindrical mold 30 is preferably 1.07 times or less, and 1.04 times or less of the outer peripheral die lip diameter D ₂ (see FIG. 2) of the annular multilayer die 20. It is more preferable. In this case, since the expansion of the multilayer cylindrical film 15 is limited, the pressurizing effect by the gas injection is more effective for the uniform rolling of the multilayer cylindrical film 15 than the expansion of the multilayer cylindrical film 15. work. As a result, the thickness accuracy can be easily improved, and variations in characteristics such as surface resistance can be suppressed. On the other hand, in order to easily maintain the cylindrical shape of the multilayer cylindrical film 15, the inner diameter D ₁ of the cylindrical mold 30 should be 1.02 times or more the outer peripheral die lip diameter D ₂ of the annular multilayer die 20. Preferably, it is 1.03 times or more. In order to obtain a seamless belt applied to the intermediate transfer belt or the transfer conveyance belt, the inner diameter D ₁ of the cylindrical mold 30, the outer peripheral die lip diameter D ₂ of the annular multilayer die 20, and the inner peripheral die lip diameter D of the annular multilayer die 20. ₃ (see FIG. 2) may be, for example, about 80 to 500 mm, 70 to 467 mm, and 69 to 466 mm, respectively.

  Moreover, as shown in FIG. 1, the cylindrical mold 30 is opened vertically upward. The annular multilayer die 20 is configured to be insertable into the cylindrical mold 30 by a hydraulic cylinder mechanism 28. When the annular multilayer die 20 is inserted into the cylindrical mold 30, the gap between the annular multilayer die 20 and the inner wall 30a of the cylindrical mold 30 is preferably set in the range of 1 mm to 100 mm. Within this range, the inner wall 30a of the cylindrical mold 30 is not damaged, and the expansion ratio of the multilayer cylindrical film 15 can be regulated within a range in which the thickness accuracy can be improved. The hydraulic cylinder mechanism 28 is controlled by the control means 10.

  The material of the annular multilayer die 20 and the cylindrical mold 30 is preferably a heat-resistant material such as stainless steel, aluminum, or glass. For example, when the inner wall 30a of the cylindrical mold 30 is coated with an organosilicon acid compound such as a silicone resin, polyimide resin, or the like, releasability can be imparted to the inner wall 30a of the cylindrical mold 30. . When the inner wall 30a of the cylindrical mold 30 has releasability, the seamless belt 18 can be easily detached from the cylindrical mold 30 in a manufacturing method described later.

  The cylindrical mold 30 of the present embodiment has a bottom portion, and a hole 31 for injecting gas is formed in the bottom portion. In addition, although the diameter of this hole 31 is not specifically limited, 1-10 mm is preferable from a viewpoint of an improvement of thickness precision, and 2-5 mm is more preferable.

  The feeder 40a receives the first polyamic acid solution 11 from the hopper 50a, and supplies (pumps) the first polyamic acid solution 11 to the annular multilayer die 20 based on a command from the control means 10. Similarly, the feeder 40b receives the second polyamic acid solution 12 from the hopper 50b, and supplies (pumps) the second polyamic acid solution 12 to the annular multilayer die 20 based on a command from the control means 10. Although supply machine 40a, 40b is not specifically limited, For example, the extruder which mainly has a gear pump, a monono pump, or a screw, a cylinder, and a drive device is preferable.

  The gas injection means 60 has a function of injecting the gas supplied from the compressor 70 into the cylindrical mold 30 through the injection nozzle 62. As this gas injection means 60, a mass flow meter (mass flow flow meter), a float area type flow meter, etc. can be used, for example. It is preferable to use air as the gas to be injected because it is readily available. However, if the reactivity during resin molding or the heat capacity of the gas is affected, other highly stable gases such as nitrogen, argon, or helium Can also be used. The gas injection means 60 may be fixed to the hole 31 without using the injection nozzle 62.

  When injecting gas by the gas injection means 60, it is desirable to inject so that the internal pressure of the hollow part of the multilayer cylindrical membrane 15 becomes substantially constant. Even when the annular multilayer die 20 moves relative to the cylindrical mold 30, the expansion ratio of the multilayer cylindrical film 15 is maintained substantially constant and the thickness is maintained by making the internal pressure substantially constant. It is possible to prevent the variation of.

  In the present embodiment, the gas injection means 60 is configured to be operable in the vertical direction by the atmospheric pressure cylinder mechanism 61. Therefore, it is also possible to insert the injection nozzle 62 from the hole 31 and inject the gas while raising the injection nozzle 62 as the annular multilayer die 20 moves upward.

  The nozzle opening of the injection nozzle 62 is usually preferably opened vertically upward, but may be opened horizontally. It is also possible to provide a plurality of injection nozzles 62.

  In the present embodiment, the case where the gas injection means 60 injects gas from the bottom side of the cylindrical mold 30 is exemplified. However, the gas injection means is provided in the annular multilayer die 20 to inject the gas while extruding the polyamic acid solution. It is good also as composition to do.

  The compressor 70 supplies gas (not shown) to the gas injection means 60. The compressor 70 supplies gas (not shown) to the atmospheric pressure cylinder mechanism 61 to control the vertical operation of the gas injection means 60. The compressor 70 is controlled by the control means 10.

  In the present embodiment, the entire operation of the manufacturing apparatus 1 is controlled by the control unit 10. However, for example, a configuration in which each element is manually operated may be employed.

  Next, an example of a manufacturing method using the manufacturing apparatus will be described with reference to FIGS. 1 and 2 and FIGS. 3A to 3D are schematic process diagrams showing an example of the present method.

  The present embodiment described below mainly includes a step of extruding the first and second polyamic acid solutions 11 and 12 which are characteristic portions of the method to form a cylindrical body (a precursor of the seamless belt 18), It has the drying process and imidation process performed subsequently.

  First, first and second polyamic acid solutions 11 and 12 are prepared. At this time, the obtained seamless belt 18 is prepared so that the content of the conductive material of each layer becomes a desired value. Next, the first and second polyamic acid solutions 11 and 12 are poured into the hoppers 50a and 50b, respectively. At this time, when the control means 10 detects that the first and second polyamic acid solutions 11 and 12 are more than a predetermined amount, the control means 10 opens the ball valves (not shown) at the bottoms of the hoppers 50a and 50b, and supplies the feeder 40a. , 40b is controlled to supply the first and second polyamic acid solutions 11, 12 respectively.

  Next, the annular multilayer die 20 is inserted into a predetermined position in the vertical lower part of the cylindrical mold 30 by the hydraulic cylinder mechanism 28. Here, the position where the annular multilayer die 20 is inserted can be arbitrarily set, but is preferably in the range of 1 mm to 100 mm from the bottom surface of the cylindrical mold 30, and more preferably in the range of 2 mm to 50 mm. Within this range, the control of the hydraulic cylinder mechanism 28 can be facilitated, and the first and second polyamic acid solutions 11 and 12 can be prevented from being bent or drawn down.

  Further, the gas injection means 60 is disposed in the hole 31 through the injection nozzle 62 by the atmospheric pressure cylinder mechanism 61. This arranging operation may be performed before or after the inserting operation of the annular multilayer die 20 or may be performed simultaneously. The injection nozzle 62 may be fixed to the hole 31 in advance.

  Next, the feeders 40 a and 40 b apply pressure to the first and second polyamic acid solutions 11 and 12, respectively, and send them to the annular multilayer die 20. The fed first and second polyamic acid solutions 11 and 12 flow through the first and second flow paths 21 and 22, respectively, and are pushed out from the annular discharge port 23 as a multilayer cylindrical film 15. Then, as shown in FIGS. 3A to 3C, along with this extrusion, the hydraulic cylinder mechanism 28 moves the annular multilayer die 20 vertically upward. Further, the gas is injected into the hollow portion of the multilayer cylindrical film 15 by the gas injection means 60 together with the extrusion of the first and second polyamic acid solutions 11 and 12. As a result, the multilayer cylindrical film 15 expands toward the inner surface side of the cylindrical mold 30 and contacts the inner surface of the cylindrical mold 30. At this stage, the multilayer cylindrical film 15 may not be in contact with the inner surface of the cylindrical mold 30.

  When the annular multilayer die 20 is raised, the first and second polyamic acid solutions 11 and 12 are dropped so that the lower ends of the first and second polyamic acid solutions 11 and 12 are always in contact with the bottom surface of the cylindrical mold 30. It is preferable to increase in accordance with the speed. By supporting the lower ends of the first and second polyamic acid solutions 11 and 12 by the bottom surface of the cylindrical mold 30 and reducing the falling speed of these, a pool of the solution is generated in the lower part of the cylindrical mold 30. This is because it is possible to prevent the occurrence of uneven thickness of the multilayer cylindrical film 15.

  The pressure of the gas injected into the hollow portion of the multilayer cylindrical film 15 (hereinafter also referred to as blow pressure) is not particularly limited, but is preferably 4 to 6 MPa, and preferably 5 to 5.5 MPa from the viewpoint of improving the thickness accuracy. More preferred.

  When the length of the multilayer cylindrical film 15 in the axial direction reaches a predetermined length, the feeders 40a and 40b stop pumping the first and second polyamic acid solutions 11 and 12, respectively. The hydraulic cylinder mechanism 28 stops the raising operation of the annular multilayer die 20. Thereafter, through a drying step and an imidization step, which will be described later, as shown in FIG. 3D, on the inner surface of the cylindrical mold 30, from the first layer 16 and the second layer 17 covering the outer periphery of the first layer 16. A seamless belt 18 is formed. According to this method, a uniform thickness is ensured by utilizing the falling weight of the first and second polyamic acid solutions 11 and 12, and the axis of the seamless belt 18 formed by the stop position of the annular multilayer die 20 is secured. You can control the length of the direction. Moreover, in this method, since the first layer 16 and the second layer 17 are formed simultaneously, the second layer 17 can be formed thin with the first layer 16 as a support. Therefore, it becomes easy to ensure the flexibility of the seamless belt 18. If the multi-layered cylindrical film 15 is not in contact with the inner surface of the cylindrical mold 30 at the stage where the pumping of the first and second polyamic acid solutions 11 and 12 is stopped, the multilayer pressure can be increased by increasing the blow pressure. The tubular film 15 may be expanded to bring the multilayer tubular film 15 into contact with the inner surface of the tubular mold 30.

  In this method, when the annular multilayer die 20 is moved, the thickness of the multilayer cylindrical film 15 can be controlled by adjusting the moving speed. That is, when the annular multilayer die 20 is moved at the same speed as the falling speed of the first and second polyamic acid solutions 11 and 12, the thickness of the multilayer tubular film 15 pushed out from the annular multilayer die 20 can be maintained. On the other hand, if it is moved at a speed slower than the self-weight fall speed, the thickness of the multilayer tubular film 15 can be increased. Conversely, if it is moved at a speed faster than the self-weight drop speed, the multi-layer tubular film 15 Can be made thinner. Moreover, the thickness adjustment of the multilayer cylindrical film 15 can be performed by controlling the blow pressure and the extrusion amount of the first and second polyamic acid solutions 11 and 12, and by adjusting these together, More precise thickness control is possible. Of these, the method of controlling the thickness by adjusting the blow pressure is preferable because it enables very simple and quick response control.

  Then, a drying process and an imidation process are demonstrated. First, as a pre-process, the cylindrical mold 30 is rotated at a predetermined rotational speed (for example, about 1000 to 2000 rpm) around its axis to perform leveling and defoaming of the coating surface.

  Next, primary heating is performed until the precursor of the seamless belt 18 formed on the inner surface of the cylindrical mold 30 can be self-supported. The heating temperature at this time is not particularly limited as long as it can evaporate the solvent used, and can be appropriately set, but is usually about 80 to 230 ° C. The heating time is appropriately set according to the heating temperature, and is usually about 10 to 60 minutes.

  Next, by secondary heating, imidation reaction, removal of residual solvent, and removal of ring-closing water are performed. The temperature of the secondary heating is not particularly limited as long as it is a temperature suitable for this purpose, but is usually about 250 ° C to 400 ° C. The heating time is appropriately set according to the heating temperature, and is usually about 10 to 60 minutes.

  Note that the primary and secondary heating are preferably performed while rotating the cylindrical mold 30 as described above. This is because variations in characteristics of the seamless belt 18 can be reduced by heating and fixing while rotating at a predetermined rotational speed.

  Then, it cools to normal temperature and peels the obtained seamless belt 18 from the cylindrical metal mold | die 30. FIG. In addition, it is preferable to apply a release agent such as a silicone resin to the inner surface of the cylindrical mold 30 in advance because the workability of peeling the seamless belt 18 is improved.

  As mentioned above, although an example of embodiment of this method was demonstrated, this method is not limited to the said embodiment. For example, when extruding the first and second polyamic acid solutions 11 and 12, in the above embodiment, an example in which the cylindrical mold 30 is fixed and the annular multilayer die 20 is moved vertically upward has been described. 20 may be fixed and the cylindrical mold 30 may be moved vertically downward. As a device for moving the cylindrical mold 30 vertically downward, for example, a lifting device such as a hydraulic cylinder mechanism or a lifting device is preferable. In this case, when the cylindrical mold 30 having no bottom is used and the cylindrical mold 30 is installed on the lifting device, the installation surface of the cylindrical mold 30 in the lifting device is the first. It will serve to support the lower ends of the first and second polyamic acid solutions 11 and 12.

  The annular multilayer die 20 may be moved vertically upward and the cylindrical mold 30 may be moved vertically downward. In this case, since any one of the annular multilayer die 20 and the cylindrical mold 30 can be used for fine adjustment of the relative moving speed, more precise film formation is possible.

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

  Evaluation examples and measurement methods thereof are shown below for Examples and Comparative Examples described later.

<Surface resistivity (ρs)>
The seamless belts obtained in each of the examples and the comparative examples under the conditions of a measurement temperature of 25 ° C. (60% RH) using a resistivity measuring device (manufactured by Mitsubishi Chemical Corporation, Hiresta UP MCP-HTP16, probe: URS) A voltage of 500 V was applied to any 12 points on the inner surface, and the surface resistivity was measured 1 minute after the start of the application. Here, the average value of 12 points measured was defined as the surface resistivity.

<Volume resistivity (ρv)>
Using the resistivity measuring device, a voltage of 100 V was applied to any 12 points on the outer surface of the seamless belt obtained in each of the examples and comparative examples under the condition of a measurement temperature of 25 ° C. (60% RH). The volume resistivity 10 seconds after the start was measured. Here, the measured average value of 12 points was defined as the volume resistivity.

<Thickness of each layer>
The cross section of each seamless belt was observed with a scanning electron microscope (SEM), and the thickness of each layer was measured.

<Example 1>
Into 1687 g of N-methyl-2-pyrrolidone (NMP), 163 g of isoquinoline (imidation catalyst) was added, and further 184 g of carbon black (MA100, manufactured by Mitsubishi Chemical Corporation, furnace black, average particle diameter of primary particles 22 nm), 100 g of poly (N-vinyl-2-pyrrolidone) as a dispersant was added. This was stirred by a ball mill for 12 hours at room temperature, and then filtered through a stainless mesh (# 400) to obtain a carbon dispersion having a carbon concentration of 10% by weight. Transfer 192.39 g of this carbon dispersion to a 5000 ml four-necked flask, add 2040.13 g of N-methyl-2-pyrrolidone and 227.09 g (2.1 mol) of p-phenylenediamine, and dissolve while stirring at room temperature. did. Next, 617.86 g (2.1 mol) of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride was added and reacted at a temperature of 20 ° C. for 1 hour. Stirring while heating for a period of time, the resulting varnish was filtered through a stainless mesh (# 800) to obtain a polyamic acid solution for inner layer (viscosity by B-type viscometer: 150 Pa · s, solid content concentration 20 wt%). . In addition, about content of the said carbon black, it adjusted so that it might become 23 weight part with respect to 100 weight part of polyimide resins in the inner layer (1st layer) formed.

  Similarly, the outer layer polyamide was prepared in the same manner as described above except that the carbon black content was adjusted to 19 parts by weight with respect to 100 parts by weight of the polyimide resin in the formed outer layer (second layer). An acid solution was obtained.

3A to 3D, the seamless belt 18 is formed from the inner layer polyamic acid solution (equivalent to the first polyamic acid solution 11) and the outer layer polyamic acid solution (equivalent to the second polyamic acid solution 12). Produced. At this time, as the tubular mold 30, the inner diameter _{D 1} is at 320 mm, the length in the axial direction is used as the 500 mm. The annular multilayer die 20 has an interval L between the annular discharge port 23 and the connecting portion 24 of 10 mm, an outer peripheral die lip diameter D ₂ and an inner peripheral die lip diameter D ₃ of 315 mm and 314 mm, respectively. The two channels 21 and 22 having substantially the same channel cross-sectional area were used. The discharge amount of the inner layer polyamic acid solution and the discharge amount of the outer layer polyamic acid solution were 207.5 g / min and 124.5 g / min, respectively. The blow pressure was 5 MPa, and the moving speed of the annular multilayer die 20 was 10 mm / second. And after discharging the polyamic acid solution for inner layers and the polyamic acid solution for outer layers to the inner surface of the cylindrical mold 30, the cylindrical mold 30 was rotated at 1500 rpm for 10 minutes to obtain a uniform coated surface. Next, the cylindrical mold 30 was heated at 150 ° C. for 15 minutes, further heated to 345 ° C. at a rate of 2 ° C./min, and heated at 345 ° C. for 10 minutes to proceed with imide conversion. In addition, in the case of the said heat processing, all performed, rotating the cylindrical metal mold | die 30 at 10 rpm. Then, it cooled to room temperature and obtained the two-layer seamless belt of Example 1.

<Example 2>
Example 2-2 was carried out in the same manner as Example 1 except that the amount of polyamic acid solution for the inner layer and the amount of polyamic acid solution for the outer layer were 290.5 g / min and 41.5 g / min, respectively. A layer seamless belt was obtained.

<Example 3>
Except that the discharge amount of the inner layer polyamic acid solution and the discharge amount of the outer layer polyamic acid solution were 249.0 g / min and 83.0 g / min, respectively, the same procedure as in Example 1 was repeated. A layer seamless belt was obtained.

<Example 4>
In the outer layer (second layer) to be formed, the two layers of Example 4 were prepared in the same manner as in Example 3 except that the content of carbon black relative to 100 parts by weight of polyimide resin was adjusted to 18 parts by weight. I got a seamless belt.

<Example 5>
In the outer layer (second layer) to be formed, the two layers of Example 5 were prepared in the same manner as in Example 3 except that the content of carbon black relative to 100 parts by weight of polyimide resin was adjusted to 20 parts by weight. I got a seamless belt.

<Comparative Example 1>
A single-layer seamless belt of Comparative Example 1 was obtained in the same manner as in Example 1 except that only a polyamic acid solution for the inner layer was used to form a film at a discharge rate of 332.0 g / min.

<Comparative example 2>
A two-layer seamless belt of Comparative Example 2 was obtained in the same manner as in Example 1 except that the discharge amount of the inner layer polyamic acid solution and the discharge amount of the outer layer polyamic acid solution were both 166.0 g / min. It was.

<Comparative Example 3>
In the outer layer (second layer) to be formed, the two layers of Comparative Example 3 were prepared in the same manner as in Example 3 except that the content of carbon black relative to 100 parts by weight of polyimide resin was adjusted to 22 parts by weight. I got a seamless belt.

<Comparative Example 4>
In the outer layer (second layer) to be formed, the two layers of Comparative Example 4 were prepared in the same manner as in Example 3 except that the content of carbon black relative to 100 parts by weight of polyimide resin was adjusted to 16 parts by weight. I got a seamless belt.

  The results of surface resistivity (ρs) and volume resistivity (ρv) of the above examples and comparative examples are shown in Table 1 below.

  As shown in Table 1, in Examples 1 to 5 of the present invention, values within an appropriate range were obtained for both ρs and ρv. On the other hand, in Comparative Examples 1 to 4, a value deviating from an appropriate range (10.5 to 13.0) for ρv was obtained.

<Outline evaluation>
Each of the two-layer seamless belts of Example 3 and Comparative Example 3 was set as an intermediate transfer belt in a printer (manufactured by Ricoh Co., Ltd., model MP C2500), and solid printing was performed on the entire surface of A4 paper. The obtained printed image is shown in FIG. 4A (Example 3) and FIG. 4B (Comparative Example 3). As shown in FIG. 4A, printing failure was not observed in Example 3 of the present invention. On the other hand, as shown in FIG. 4B, white spots occurred in Comparative Example 3.

<Confirmation of offset failure>
The two-layer seamless belts of Example 4, Comparative Example 2 and Comparative Example 4 are set as intermediate transfer belts in a printer (manufactured by Ricoh, model MP C2500), and the printing speed is up to 20 sheets (A4 size) / min. And continuously printing. As a result, in Example 4 of the present invention, the print quality was good, but in Comparative Example 2 and Comparative Example 4, the toner was affected by the charging during the previous printing in the second and subsequent printing. As a result, a phenomenon in which the two images overlap (offset failure) occurred.

It is a schematic block diagram which shows an example of the manufacturing apparatus used for the suitable manufacturing method of the two-layer seamless belt of this invention. It is a schematic sectional drawing of the cyclic | annular multilayer die used for the manufacturing apparatus of FIG. AD is a general | schematic process figure which shows an example of the suitable manufacturing method of the two-layer seamless belt of this invention. A is a print image showing the white spot evaluation result of Example 3, and B is a print image showing the white spot evaluation result of Comparative Example 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Manufacturing apparatus 10 Control means 11 1st polyamic-acid solution 12 2nd polyamic-acid solution 15 Multilayer cylindrical film | membrane 16 1st layer 17 2nd layer 18 Seamless belt 20 Annular multilayer die 21 1st flow path 22 2nd flow path 23 Annular Discharge port 24 Connection portion 28 Hydraulic cylinder mechanism 30 Cylindrical mold 30a Inner wall 31 Holes 40a, 40b Feeders 50a, 50b Hopper 60 Gas injection means 61 Pneumatic cylinder mechanism 62 Injection nozzle 70 Compressor

Claims (2)

In a seamless belt having a first layer containing a polyimide resin and a conductive material, and a second layer covering the outer periphery of the first layer and containing a polyimide resin and a conductive material,
The content (W ₁ ) of the conductive material with respect to 100 parts by weight of the polyimide resin in the first layer is 21 to 25 parts by weight , and the content (W ₂ ) of the conductive material with respect to 100 parts by weight of the polyimide resin in the second layer is 17 to. 21 parts by weight and the value of W ₁ / W ₂ is 1.21 to 1.40,
The thickness (T ₁ ) of the first layer is 50 to 75 μm, the thickness (T ₂ ) of the second layer is 5 to 30 μm, and the value of T ₁ / T ₂ is 1.6 to 6.8. A seamless belt characterized by The seamless belt according to claim 1 , wherein the conductive material contained in the first and second layers is carbon black.

Images