JP4749842B2 - Seamless belt manufacturing method and manufacturing apparatus thereof - Google Patents

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seamless belt manufacturing method and a manufacturing apparatus therefor, and in particular, a transfer conveyance body, an intermediate transfer body, and the like used for an electrophotographic copying machine, a printer, a facsimile, and a composite machine including these image forming apparatuses, It is useful when manufacturing a transfer belt and a seamless belt used for the fuser.

  Various methods for producing a seamless belt have been proposed. For example, a seamless belt is manufactured by applying a resin solution in a spiral shape from the varnish outlet 43a of the dispenser 43 to the inner surface 44a or the outer surface of the cylindrical mold 44 at a constant pressure using the coating liquid pump 41 and the pressure gauge 42. (Refer to FIG. 4 and Patent Document 1), and while forming a hollow layer of the resin solution, the resin solution is pushed into the cylindrical mold from the extruded cylinder mold inscribed in the cylindrical mold. In addition, there is a method of manufacturing a seamless belt by applying while injecting gas into the hollow cylindrical layer (see Patent Document 2).

JP 2002-18872 A JP 2004-237695 A

  Conventionally, as a method for transferring a visible image onto a transfer paper such as paper, a transfer drum method for winding a transfer paper such as paper on a transfer drum and transferring the visible image on the photosensitive member to the transfer paper for each color, An intermediate transfer body method is known in which a visible image on a photosensitive member is transferred to an intermediate transfer member for each color and then transferred to a transfer sheet at a time.

  In recent years, due to the trend of higher speed and higher image quality in image forming devices and the choice of paper types, as a new image forming device that uses intermediate transfer members, multiple image carriers equipped with developing devices for each color are used for intermediate transfer. A color image forming apparatus of a tandem type intermediate transfer system that arranges in series on the body, transfers the visible image on the photosensitive member for each color onto the intermediate transfer body, and then transfers the image to a transfer body such as paper at once. It is being considered.

  This tandem intermediate transfer method can improve the image formation speed compared to the conventional transfer method, and is considered as a promising transfer method in the future because it does not select the transfer target like the transfer drum method. Yes.

  However, the intermediate transfer member in this transfer system has a diameter larger than that of the conventional intermediate transfer belt and is provided with independent four-color developing devices, so that a highly accurate apparatus design is required for each color. For this reason, an intermediate transfer member mounted on such an image forming apparatus is required to have a high elastic modulus and thickness accuracy.

  The seamless belt manufactured by the spiral coating method of Patent Document 1 is an effective method because it does not use thickness accuracy or extra resin solution. However, in the spiral coating method, a portion that is applied in a spiral shape (a portion that is detected as a streak) or undulation occurs, and a small resistance difference occurs between this portion and other portions. It was. When the seamless belt manufactured by this method is used for an intermediate transfer member of a tandem intermediate transfer system, image unevenness is caused by this minute resistance difference.

  Moreover, the seamless belt manufactured by patent document 2 can obtain a thing with uniform thickness accuracy. However, since the cylindrical mold and the extruded cylindrical mold are inscribed, when the cylindrical mold is taken in and out at the time of manufacture, the inner surface of the cylindrical mold is likely to be scratched. It is necessary to accurately position the mold and the extruded cylindrical mold and to control the operation of the extruded cylindrical mold inscribed in the cylindrical mold with high precision.

  An object of the present invention is to solve the above-described problems in the prior art and achieve the following objects. That is, an object of the present invention is to produce a seamless belt with a high elastic modulus and a very good thickness accuracy at a low cost, reduce a resistance difference in a minute section of the belt surface, and cause no image unevenness. It is an object of the present invention to provide a method for manufacturing a seamless belt and an apparatus for manufacturing the same, which can be used for an intermediate transfer member of the type.

  As a result of intensive studies to solve the above problems, the following invention has been completed.

  That is, the method for producing a seamless belt in the present invention is the production of a seamless belt in which a resin solution, which is a raw material of a seamless belt, is applied seamlessly to the inner surface of a cylindrical shape of a mold, and then dried and cured to form a film. A method in which a resin solution is extruded into a hollow cylinder using an extrusion means inside a mold, and a gas is injected into a hollow portion of the extruded cylindrical resin solution so that the expansion ratio of the cylindrical resin solution is 3 or less. And a step of applying to the inner surface of the mold.

  According to such a configuration, the hollow cylindrical resin solution can be expanded and applied to the inner surface of the mold without the extrusion means damaging the inner surface of the mold. The inner surface of the mold has a cylindrical shape, the extruded shape of the resin solution has a hollow cylindrical shape, and the expansion ratio is set within a predetermined range, so that the expansion ratio in the circumferential direction of the belt becomes constant, and a uniform circumferential length or emergency In addition, a seamless belt with good thickness accuracy can be obtained.

  In the production method of the present invention, it is desirable to move the extrusion means relative to the mold while keeping the internal pressure of the hollow portion of the cylindrical resin solution substantially constant.

  According to this configuration, by injecting the gas so as to keep the internal pressure of the hollow portion of the cylindrical resin solution substantially constant, the cylindrical resin solution extruded while moving is expanded with a constant acting force. As a result, the expansion ratio in the circumferential direction of the belt becomes constant, and a seamless belt having a uniform circumferential length and a very good thickness accuracy can be obtained.

  Further, the semiconductive belt produced by the manufacturing method of the present invention has a small resistance difference in a minute section of the belt, and the surface resistance ratio on both sides when the surface resistance is measured at a pitch of 5 mm is 1.5 or less. In particular, it is suitable for an intermediate transfer member of a tandem intermediate transfer system.

The method for producing a seamless belt according to the present invention further includes a step of sucking the resin solution when the pushing out of the resin solution from the extruding unit to the hollow cylinder is stopped. .

  According to such a configuration, after the resin solution extrusion process is completed, the resin solution hangs down inside the mold, adheres to the extruded resin solution, does not cause a failure, and can further reduce the loss of the resin solution. .

  In addition, the seamless belt manufacturing apparatus of the present invention includes an extrusion means for extruding a resin solution that is a raw material of the seamless belt, a mold having a cylindrical inner surface into which the extrusion means can be inserted, and a gas is injected into the mold. The gas injection means and the extrusion means are inserted into the mold, and while the extrusion means and the mold are separated, the extrusion means pushes the resin material into a hollow cylindrical shape, and the gas injection means discharges the gas into the cylindrical resin. Injecting into the hollow portion of the solution so that the internal pressure of the hollow portion becomes substantially constant, and having a control unit for controlling to be applied to the inner surface of the mold by expanding at an expansion ratio of 3 or less. To do.

In the seamless belt manufacturing apparatus of the present invention, the extrusion means further includes a suction means for sucking the resin solution, and the suction means stops the extrusion means from pushing the resin solution downward in a hollow cylindrical shape. In this case, the resin solution is sucked .

  The effect of the seamless belt manufacturing apparatus is the same as that of the seamless belt manufacturing method described above.

  Moreover, the resin solution which is the raw material of the seamless belt manufactured by the seamless belt manufacturing method and the manufacturing apparatus of the present invention has a resin content concentration in the range of 10 to 40% by weight, and the B-type viscosity of the resin solution. It is desirable to use one having a viscosity (5 to 1000 Pa · s) as measured (25 ° C.).

  According to such a configuration, when the tip portion of the extruded resin solution comes into contact with the bottom of the mold, the resin solution has a supporting force that does not cause bending or collapse (drawdown) due to its own weight, and the like. A seamless belt having a uniform thickness can be produced without causing a partial thickness variation (uneven thickness portion) of the resin solution due to expansion caused by gas injection.

  Further, the expansion ratio of the resin solution in the seamless belt manufacturing method and the manufacturing apparatus of the present invention is preferably 3 or less, and more preferably 2 or less. When the expansion ratio exceeds 3, the resin solution is ruptured or the thickness variation becomes large, which is not preferable as a seamless belt.

  Moreover, when the extrusion means in the seamless belt manufacturing method and manufacturing apparatus of the present invention is inserted into the mold, it is desirable that the clearance between the extrusion means and the inner surface of the mold is 1 mm or more. If this gap is smaller than 1 mm, scratches are likely to occur on the inner surface of the mold, which is not preferable.

  Embodiments of the present invention will be described below.

<Seamless belt materials>
Polyimide resin, polyamideimide resin, polyetherimide resin, polyarylate resin, aromatic polyester resin, wholly aromatic polyamide resin, etc. can be used as a raw material resin for seamless belts manufactured by the manufacturing method and manufacturing apparatus of the present invention. . Moreover, these can also be blended and used. In particular, when the seamless belt of the present invention is used as a transfer fixing body or a fixing belt, a heat resistant strength is required, and therefore a polyimide resin and a polyamideimide resin are preferable, and a thermosetting polyimide resin is more preferable. .

  As a raw material liquid for the polyimide resin, for example, a polyamic acid solution can be suitably used. This polyamic acid is obtained by reacting an acid dianhydride or a derivative thereof and an approximately equimolar amount of diamine in an organic solvent, and is usually used in the form of a solution, so that it is used as a main component of the resin solution used in the present invention. be able to.

  Examples of suitable acid dianhydrides include pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic acid dianhydride. Anhydride, 2,3,3 ′, 4-biphenyltetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride Products, 1,4,5,8-naphthalenetetracarboxylic dianhydride and the like.

  Examples of 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′-diaminodiphenyl sulfone, 4,4′-diaminodiphenyl sulfide, 4,4′-diaminodiphenylpropane and the like can be mentioned.

  As the organic solvent, acetone, chloroform, methyl ethyl ketone, tetrahydrofuran, dioxane, acetonitrile, alcohols (methanol, ethanol, isopropanol, etc.), N, N-dimethylacetamide, dimethylformamide, N-methylpyrrolidone (NMP), etc. are used. However, N, N-dimethylacetamide, NMP, and dimethylformamide, which are polar amide solvents, are preferable.

  When the seamless belt produced in the present invention is used as an intermediate transfer member or a transfer conveyance belt, a high elastic modulus is required. Specifically, the tensile elasticity in the circumferential direction measured according to JIS K 7127. The rate is preferably 2000 MPa or more. Therefore, from this viewpoint, it is necessary to select the main component of the resin solution.

  Further, when the seamless belt produced in the present invention is used as an intermediate transfer member, a transfer carrier, or a transfer fixing member, it is necessary to add various conductive materials to the resin in order to obtain semiconductivity. Specifically, various kinds of carbon, aluminum, nickel, tin oxide, inorganic compounds such as potassium titanate, and conductive polymers typified by polyaniline and polypyrrole can be used. In particular, in order to make the entire belt have a uniform resistance, it is important to uniformly disperse various conductive materials. Therefore, when carbon black or the like is used, it is necessary to select a carbon black having good dispersibility and a dispersion method as appropriate.

  Moreover, when using a conductive polymer etc., it is desirable to melt | dissolve in the same solvent as the resin material is melt | dissolved.

  The content of these various conductive materials can be appropriately selected according to the type of the conductive material, but is preferably about 5 to 50% by weight, more preferably 7 to 40% by weight with respect to the resin. When the content is less than 5% by weight, the uniformity of electrical resistance is lowered, and the surface resistivity may be greatly lowered during durable use. On the other hand, if it exceeds 50% by weight, it is difficult to obtain a desired resistance value, and it becomes fragile as a molded product of a seamless belt, which is not preferable.

  The resin solution of the present invention preferably has a solution viscosity of 5 to 1000 Pa · s measured at a B-type viscometer at 25 ° C. When the solution viscosity is less than 5 Pa · s, if a small amount of dust or foreign matter is mixed in the initial drying process, the solution resin will be repelled from that point, and the portion will become thin, resulting in a defective product. Conventionally, a method of slowing the drying rate has been adopted as a workaround, but this is not a preferable method because the manufacturing time becomes longer and the productivity is lowered. As another countermeasure, there is a method of installing a device for preventing the entry of dust and foreign matter, but this is not preferable because it leads to an increase in cost.

  On the other hand, when the solution viscosity exceeds 1000 Pa · s, the resin is difficult to spread, and it is difficult to form a uniform thickness, which is not preferable.

  In addition, as the gas to be injected in the present invention, air is usually preferable because it is easily available. However, when the reactivity during resin molding or the heat capacity of the gas is affected, nitrogen, argon, helium, etc. Other gases with high stability can also be used.

<Manufacturing equipment>
Below, the manufacturing apparatus of the seamless belt in this invention is demonstrated using FIG. In FIG. 1, the manufacturing apparatus 1 includes a control means 10, an extrusion means 20, a mold 30, a feeder 40, a hopper 50, an injection means 60, a compressor 70, and other components not shown.

  The control means 10 controls the operation of the manufacturing apparatus 1. The control means 10 is configured to operate the feeder 40, the vertical operation of the extrusion means 20, based on the set values of the manufacturing conditions input by the user via the input means such as a touch panel and buttons, or stored in advance in the memory. The operation of the injection means 60 is controlled. The control means 10 can be usually realized by a CPU, a memory or the like. The processing procedure for realizing the function of the control means 10 is usually realized by software, and the software is recorded in a recording medium such as a ROM or a flash EEPROM. In addition, the software program may be realized by a dedicated circuit or may be realized by firmware. The manufacturing conditions and manufacturing status (real-time status) are displayed on the display means and can be appropriately confirmed. The control program shown in FIG. 1 is a software program for the control means 10. The condition setting module is a functional module for setting manufacturing conditions of the manufacturing apparatus 1. The manufacturing condition table is a table of manufacturing conditions set in advance, and is configured to be appropriately changed by the function of the condition setting module.

  The extruding means 20 includes, for example, an annular die 21 for extruding a resin solution, a suction means 22 and other members. The resin solution can be extruded from the annular die 21 into a hollow cylinder. The ratio of the outer diameter of the hollow cylindrical resin solution to the inner diameter of the mold 30 (corresponding to the expansion ratio) is preferably 3 or less, more preferably set to a range greater than 1 and 2 or less, In particular, it is more preferable to set in the range of 1.03 to 1.5. Since the pushing means 20 is inserted into the mold 30, the expansion ratio is greater than 1. Increasing the expansion ratio is not preferable because tearing is likely to occur during gas injection and the thickness of the belt varies. That is, the lower limit value of the expansion ratio is determined by the diameter of the inner surface of the mold 30 and the size of the annular die 21, and the upper limit value of the expansion ratio is determined within a range where the thickness of the belt does not vary.

  The pushing means 20 is configured to be inserted into the mold 30 by a hydraulic cylinder mechanism 28. When the extrusion means 20 is inserted into the mold 30 and disposed, the gap between the annular die 21 and the inner surface of the mold 30 needs to be set in consideration of the expansion ratio and not damaging the inner surface of the mold 30. However, this gap is preferably at least 1 mm or more, and more preferably 1 mm or more and 100 mm or less. If the gap is smaller than 1 mm, the annular die 21 may be inserted into the mold 30 and may be scratched on the inner surface of the mold 30 due to factors such as mechanical vibration when moving vertically inside. Yes, not preferred. Further, when the gap is increased, the expansion ratio is increased, which is not preferable.

  The suction means 22 has a function of sucking the resin solution in the middle of the resin solution flow path. FIG. 2 shows an example of a part of a cross section of the extrusion means 20. As shown in FIG. 2A, when the resin solution is being pushed out, the suction means 21 is pushed into a predetermined position. Then, as shown in FIG. 2 (b), when the cylindrical suction means 22 is pulled up vertically, the resin solution is sucked to form a reservoir 22a. By comprising in this way, the dripping of a resin solution can be prevented. Here, the mechanism for vertically operating the cylinder-shaped suction unit 22 is not particularly limited, but normally, a hydraulic cylinder mechanism or an air cylinder mechanism can be used, and the vertical operation is controlled by the control unit 10.

  The operation of the suction unit 22 may be performed, for example, when the extrusion of the resin solution by the extrusion unit 20 is stopped or before and after that, and further, in order to prevent liquid dripping due to vibration during insertion or stop, It is also possible to perform it in conjunction with the movement of the pushing means 20 moving inside the mold 30.

  The material of the annular die 21 and the suction means 22 constituting the extruding means 20 is not particularly limited and can be appropriately selected. Usually, a metal can be used, and in particular, mold tool steel (for example, SKD4, SKD5). , SKD6, SKD61, SKD7, SKD8, SKT4, etc.) are particularly preferred.

  As a mechanism for preventing liquid dripping, a mechanism for closing the outlet portion of the resin solution of the annular die 21 with a valve or the like is possible. However, since the liquid dripping prevention mechanism by the suction means 22 is a simple mechanism, it is cleanable. And is excellent because it is excellent in maintainability.

  Further, in order to achieve high-precision thickness accuracy of the belt, it is important to set the slit outlet at the tip of the annular die 21 to a uniform width in the circumferential direction. Therefore, as shown in FIG. 2, by attaching a movable adjustment ring 24 to the inner die 23 side of the annular die 21, the width of the slit from which the resin solution is discharged can be finely adjusted to achieve highly accurate thickness variation. Can do.

  Although it is possible to attach a movable adjustment ring on the outer die 25 side, the thickness of the outer die 25 is further increased by the amount of the adjustment ring, and a bolt or the like for adjusting the outer die 25 is provided on the annular die 21. It protrudes to the outside, and the entire outer diameter of the pushing means 20 is increased. In order to allow the extruding means 20 to be inserted into the mold 30, the outer diameter of the annular die 21 must be reduced, resulting in an unfavorable increase in the expansion ratio of the resin solution.

  Examples of the material of the mold 30 include various types such as metal, glass, and ceramic from the viewpoint of heat resistance, but mold tool steel (for example, SKD4, SKD5, SKD6, SKD61, SKD7, or SKD8). , SKT4, etc.) are more preferable. Since the die 30 determines the outer diameter of the hollow cylindrical seamless belt, it is necessary to have at least a cylindrical hole, and the shape of the die 30 is preferably a hollow cylindrical shape. In addition, the bottom portion of the mold 30 has a hole 31 for injecting gas. The diameter of the hole 31 is not particularly limited, but can be appropriately set depending on the gas injection means 60, the type of gas, the injection pressure, and the like.

  A seamless belt having a desired outer diameter and width can be manufactured by appropriately setting the inner diameter and the columnar height of the mold.

  The supply unit 40 receives the resin solution from a hopper 50 provided for supplying the resin solution, and supplies (pumps) the resin solution to the extrusion unit 20 based on a command from the control unit 10. The feeder 40 is not particularly limited, but for example, a gear pump, a Mono pump, or an extruder mainly composed of a screw, a cylinder, and a driving device is preferable.

  The gas injection means 60 is usually fixed in advance in the hole 31 and has a function of injecting the gas supplied from the compressor 70 into the mold 30.

  Moreover, when injecting gas, it is desirable to inject so that the internal pressure of the hollow part of a liquid solution may become substantially constant. Even when the extruding means 20 moves relative to the mold 30, by making the internal pressure substantially constant, the expansion ratio can be maintained substantially constant, and variations in thickness can be prevented.

  The gas injection means 60 is configured to be vertically operable by the air cylinder mechanism 61, the injection nozzle 62 is inserted from the hole 31, and the gas is injected while vertically operating in accordance with the vertical operation of the extrusion means 20. You can also.

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

  In addition, in the manufacturing apparatus 1 shown in FIG. 1, although the gas injection | pouring means 60 showed the method of inject | pouring gas from the bottom part side of the metal mold | die 30 as a gas injection | pouring method, it is not specifically limited to this method, Extruding means A method may be used in which a gas injection mechanism is provided in 20 and gas is injected together with the extrusion of the resin solution.

  The compressor 70 supplies gas (not shown) to the gas injection means 60. The compressor 70 supplies air (not shown) to the air cylinder mechanism 61 to control the vertical operation of the gas injection means 60. The compressor 70 can supply air to other air-driven mechanisms. The compressor 70 is controlled by the control means 10.

  The entire operation of the seamless belt manufacturing apparatus 1 is configured to be performed by the control means 10, but is not particularly limited thereto, and for example, each element can be manually operated.

<Manufacturing method>
Below, the manufacturing method of a seamless belt is demonstrated using FIG. In addition, in the following description, although demonstrated using the component of the manufacturing apparatus 1 demonstrated above, the manufacturing method of this invention is not limited to the manufacturing apparatus 1, It can apply also to another apparatus.

  The method for producing a seamless belt according to the present invention mainly includes a step of producing a solution-like resin material that is a raw material for a seamless belt, and a method for applying a hollow cylindrical resin solution extruded from an extrusion means to the inner surface of a mold. Furthermore, it has the process of apply | coating to a metal mold | die inner surface, inject | pouring gas in the inside of a hollow cylindrical resin solution, a drying process, and the process of performing an imidation reaction.

  First, a resin solution is prepared. The adjusted resin solution is poured into the hopper 50. When it is detected that the resin solution is more than a predetermined amount, the control means 10 opens the ball valve (not shown) at the bottom of the hopper 50 and controls to supply the resin solution to the feeder 40.

  The hydraulic cylinder mechanism 28 inserts the pushing means 20 into a predetermined position inside the mold 30 vertically below. Here, the insertion position can be set arbitrarily, but a position of 1 mm to 100 mm from the bottom surface of the mold 30 is preferable, and a position of 2 mm to 50 mm is more preferable. If it is smaller than 1 mm, it is necessary to control the hydraulic cylinder mechanism 28 with high accuracy, and if it is larger than 100 mm, the resin solution is liable to be bent or drawn down, which is not preferable.

  The gas injection means 60 sets the injection nozzle 62 in the hole 31 by the air cylinder mechanism 61. This setting operation may be performed before or simultaneously with the insertion operation of the pushing means 20. The injection nozzle 62 may be fixed to the hole 31 in advance.

  Next, the feeder 40 applies pressure to the resin solution that has flowed in and feeds it into the extrusion means 20. The sent resin solution flows through the flow path of the extrusion means 20 and is finally pushed out from the slit portion of the annular die 21 into a hollow cylindrical shape. The thickness of the extruded resin solution is finely adjusted by the adjustment ring 24 and becomes uniform. Along with this extrusion, the extrusion means 20 is moved vertically upward by the hydraulic cylinder mechanism 28. The extrusion speed is proportional to the pressure of the feeder 40 and is controlled by the control means 10.

  Further, gas is injected from the injection nozzle 62 together with the extrusion of the resin solution. As a result, the resin solution expands to the inner surface side of the mold 30 and is applied to the inner surface of the mold 30. In FIG. 3, the extrusion means 20 is inserted into the mold 30, and the resin solution is extruded while moving vertically upward, and air (not shown) is injected from the holes 31, and the resin solution expands and molds. The state applied to the inner surface of 30 was shown. As shown in FIG. 3, since the gas is injected so that the internal pressure of the hollow portion of the resin solution becomes substantially constant, the resin solution is uniformly applied to the inner surface of the mold 30.

  Here, the pressure of the injected gas (hereinafter referred to as blow pressure) is not particularly limited, but the air flow rate is controlled so that the internal pressure of the hollow portion of the resin solution becomes substantially constant. If the blow pressure is too small, the resin solution cannot be expanded. If the blow pressure is too large, the thickness varies, which is not preferable.

  Note that the injection nozzle 62 can be inserted into the mold 30 as the push-out means 20 moves vertically upward, so that the vertical movement is possible.

  Next, when stopping the extrusion of the resin solution, the feeder 40 stops the pumping of the resin solution, and the hydraulic cylinder mechanism 28 stops the vertical operation of the extrusion means 20. Further, the suction means 22 operates vertically upward to suck the resin solution. This prevents dripping.

  Next, the resin solution uniformly applied to the inner surface of the mold 30 is heated. First, primary heating is performed until self-supporting is possible. The heating temperature is not particularly limited as long as it is a temperature at which the applied solvent can be evaporated, and can be appropriately set, but is preferably 80 to 230 ° C. The heating time is appropriately set according to the heating temperature, and is usually about 10 to 60 minutes. At this time, if heated rapidly at 230 ° C., the solvent in the resin solution rapidly evaporates, so microvoids are generated. If heated for less than 80 ° C. for a long time, it takes too much production time and productivity is lowered, which is not preferable. .

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

  A seamless belt peeled off from the mold 30 after primary heating is inserted outside the cylindrical second mold used to regulate the inner diameter of the seamless belt, and secondary heating is performed in this inserted state. It is also possible.

  Next, the seamless belt applied and cured on the inner surface of the mold 30 is peeled off. As this peeling method, for example, a method of pressure-feeding air to a minute through-hole provided in advance on the peripheral wall of the end of the mold can be used. In addition, it is preferable to perform a release treatment with a silicone resin or the like on the peripheral surface of the mold 30 in advance because the workability of peeling the seamless belt is improved.

  The seamless belt obtained by the above manufacturing method has a high elastic modulus and very good thickness accuracy, and the ratio of the resistances on both sides when the surface resistance is measured at a pitch of 5 mm is 1.5 or less. The difference in surface resistance is very small. Therefore, even if this seamless belt is used as an intermediate transfer belt for a color printer or the like, it is very good without color unevenness.

  In the description of FIG. 1 and FIG. 3, the pushing means 20 is configured to be inserted into the fixed mold 30 and the pushing means 20 operates vertically. However, the present invention is not limited to this configuration. In addition, the extrusion means 20 is fixed, and the mold 30 can be configured to move vertically, and both the extrusion means 20 and the mold 30 can be configured to operate vertically. . As a device for vertically operating the mold 30 in such a configuration, for example, a hydraulic cylinder mechanism, a lifting device or the like is preferable.

<Example>
Hereinafter, the present invention will be described more specifically with reference to examples. However, these examples do not limit the present invention.

(Evaluation methods)
(1) Evaluation of surface resistance (whole) Hiresta UP MCP-H1450 (manufactured by Mitsubishi Chemical Co., Ltd., probe UR) is used as a measuring instrument, and a voltage of 100 V is applied to any 24 points on the surface of the semiconductive belt under measurement conditions of 25 ° C. The surface resistance value 10 seconds after the start of application was measured. Here, the average value of the 24 points measured was defined as the surface resistance.

(2) Evaluation of surface resistance ratio (minute interval) Hiresta UP MCP-H1450 (Mitsubishi Chemical Corporation, probe: UA) was used as a measuring instrument, and the semiconductive belt was spaced at 5 mm intervals in the width direction under measurement conditions of 25 ° C. A voltage of 100 V was applied, and the surface resistance value 10 seconds after the start of application was measured. Here, the ratio of the surface resistance values of two adjacent measurement points was obtained at all the measurement points, and the maximum value of the ratio was defined as the surface resistance ratio.

(3) Thickness / Thickness Variation A total of 50 points were measured, 10 points in the circumferential direction and 5 points in the width direction of the belt, and the average value was obtained. Further, the thickness variation is defined as the difference between the maximum value and the minimum value of the measured data.

(4) Evaluation of image transferability The obtained semiconductive belt was incorporated into a commercially available copying machine as an intermediate transfer belt, and image evaluation was performed. The evaluation was good when a clear and accurate image was obtained, and bad when a defect or change was found in the image.

Example 1
Carbon black (SPECIAL BLACK4, manufactured by Degussa) was added to N-methyl-2-pyrrolidone (NMP) and stirred for 8 hours with a ball mill to obtain a carbon black-dispersed NMP solution. In this carbon black-dispersed NMP solution, equimolar numbers of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and 4,4′-diaminodiphenyl ether are dissolved and stirred at room temperature for 5 hours in a nitrogen atmosphere. Then, the viscosity was adjusted to obtain a polyamic acid solution (solid content 20 wt%, solution viscosity 300 B · s at 25 ° C. using a B-type viscometer). A hollow resin solution (thickness 70 μm) extruded from 420 g of this polyamic acid solution from an annular die (outer diameter 250 mm, length 500 mm) is applied to the inner surface of the cylindrical mold (inner diameter 300 mm, length 850 mm). At this time, using an apparatus as shown in FIG. 1, gas was injected into the hollow resin solution and expanded to be applied to the inner surface of the cylindrical mold. The expansion ratio at this time is 1.20, and the gap between the annular die and the inner surface of the mold is 25 mm. Next, after heating at 130 ° C. for 20 minutes, the temperature is raised to 360 ° C. at a rate of 10 ° C./min in order to remove the residual solvent, remove the decyclized water, and complete the imidization reaction, and then The mixture was heated at 360 ° C. for 30 minutes and then cooled to room temperature. Unnecessary portions at both ends and the center portion of the obtained belt were cut to obtain two semiconductive belts. When this belt was mounted as an intermediate transfer belt of a tandem intermediate transfer type image forming apparatus and image formation was performed, a good image without color unevenness was obtained. In addition, the surface resistance ratio in the minute section was 1.11, which was much smaller than that of the comparative example.

(Comparative Example 1)
420 g of the polyamic acid solution of Example 1 was applied to the inner surface 44a of the cylindrical mold 44 (inner diameter: 300 mm, length: 850 mm) using a spiral coating apparatus as shown in FIGS. The distance between the dispenser 43 and the mold inner surface 44a was 4 mm. Moreover, the varnish exit slit of the dispenser has a horizontal width of 30 mm and a vertical length of 0.5 mm. This coating device applies varnish in a spiral shape with a discharge rate of 2.5 cc / sec. At this time, coating was performed so that the varnish (polyamic acid solution) applied to the mold 44 overlapped with a width of 1 mm. Next, after rotating at 1500 rpm for 10 minutes and heating at 130 ° C. for 20 minutes, the temperature is increased to 360 ° C. at 10 ° C./min in order to remove residual solvent, remove ring-closing water, and complete imidization reaction. The temperature was raised at a temperature rate, then heated at 360 ° C. for 30 minutes, and then cooled to room temperature. When the obtained belt was mounted as an intermediate transfer belt of a tandem type intermediate transfer type image forming apparatus and image formation was performed, color unevenness occurred.

The figure which shows the example of the manufacturing apparatus in embodiment The figure which shows the example of a part of cross section of the extrusion means in embodiment The figure which shows the example of the manufacturing method in embodiment The figure which shows the example of the spiral coating apparatus of a comparative example Sectional view of outlet slit of spiral coating device of comparative example

Explanation of symbols

1 Seamless belt manufacturing equipment
DESCRIPTION OF SYMBOLS 10 Control means 20 Extrusion means 21 Annular die 22 Suction means 23 Inner ring 24 Adjustment ring 25 Outer die 28 Hydraulic cylinder mechanism 30 Mold 31 Hole 40 Feeder 50 Hopper 60 Gas injection means 61 Air cylinder mechanism 62 Injection nozzle 70 Compressor

Claims (6)

A seamless belt manufacturing method in which a resin solution, which is a raw material of a seamless belt, is applied seamlessly to a cylindrical inner surface of a mold, and then dried and cured to form a film,
The resin solution is extruded into a hollow cylinder inside the mold using an extrusion means, and a gas is injected into the hollow portion of the extruded cylindrical resin solution to expand the cylindrical resin solution at an expansion ratio of 3 or less. Applying to the inner surface of the mold ,
And a step of sucking the resin solution when stopping the extrusion of the resin solution downward from the extrusion means into a hollow cylinder .   The method for producing a seamless belt according to claim 1, wherein the extrusion means is moved relative to the mold while keeping the internal pressure of the hollow portion of the cylindrical resin solution substantially constant. Wherein the range concentration of the resin content of 10 to 40 wt% of the resin solution, viscosity by a B type viscometer of the resin solution, seamlessly according to claim 1 or 2 which is 5~1000Pa · s (25 ℃) A method for manufacturing a belt. The seamless belt manufacturing method according to any one of claims 1 to 3 , wherein a gap between the extrusion means and the inner surface of the mold when the extrusion means is inserted and disposed inside the mold is 1 mm or more. Method. Extrusion means for extruding the resin solution that is the raw material of the seamless belt;
A mold having a cylindrical inner surface into which the pushing means can be inserted;
Gas injection means for injecting gas into the mold;
The extruding means is inserted into the mold, and the extruding means pushes the resin solution into a hollow cylinder while the extruding means and the mold are separated from each other, and the gas injecting means supplies the gas to the cylinder. Control means for injecting the hollow resin solution into the hollow portion so that the internal pressure of the hollow portion is substantially constant, expanding the hollow resin solution at an expansion ratio of 3 or less, and applying to the inner surface of the mold. ,
The extruding means comprises a suction means for sucking the resin solution,
The said suction means is a manufacturing apparatus of a seamless belt which attracts | sucks a resin solution, when the said extrusion means stops pushing down the said resin solution to a hollow cylinder shape . The seamless belt manufacturing apparatus according to claim 5 , wherein a gap between the extrusion means and the inner surface of the mold when the extrusion means is inserted and arranged in the mold is 1 mm or more.

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