JP2007144817A - Method for producing endless belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an endless belt which is easily extracted from a core body and the endless belt produced by the method. <P>SOLUTION: The method for producing the endless belt includes: a first paint film forming process in which the cylindrical core body is rotated in the peripheral direction around its axis, and a first membrane forming resin solution is dropped on the peripheral surface of the core body and smoothed by a smoothing member to form the first paint film; a second paint film forming process in which a second membrane forming resin solution is dropped on the outside in the axial direction of the cylindrical core body of the first paint film on the peripheral surface of the rotating core body and smoothed by the smoothing member to form the second paint film adjoining the first paint film; a resin membrane forming process in which the first and second paint films are heated to form a first resin membrane and a second resin membrane with a thermal expansion coefficient smaller than that of the first resin membrane; and an extraction process for extracting the first and second resin membranes from the cylindrical core body, and the endless belt produced by the method is provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an endless belt manufacturing method in which a solution of a film-forming resin is applied onto a core body, and the formed resin film can be easily extracted from the core body, and to an endless belt manufactured by the manufacturing method. The endless belt is particularly preferably used for an electrophotographic image forming apparatus such as a copying machine or a printer.

  In the image forming apparatus, a belt made of a thin plastic film may be used to reduce the size / performance of the photosensitive member, the charging member, the transfer member, and the fixing member. If there is a seam in the belt, a trace of the seam is generated in the output image. Therefore, an endless belt without a seam is preferable. The material is preferably a polyimide resin or a polyamideimide resin in terms of strength, dimensional stability, heat resistance, and the like. (Appropriately, polyimide is abbreviated as PI and polyamideimide is abbreviated as PAI)

  As a method for producing a PI resin endless belt, there is a conventionally known technique in which a tip of a dispenser is brought into contact with the surface of a rotated cylindrical core, and a resin solution is supplied from the dispenser and applied. In this method, when a high viscosity solution having a viscosity of 1 to 1500 Pa · s at 25 ° C. is discharged, the solution is not sufficiently smoothed, and spiral streaks may remain, which is not preferable (for example, patents). Reference 1).

  Therefore, there is a method of smoothing the discharged solution with a blade. In this method, since the discharged solution is smoothed with a blade, the solution does not become a spiral streak, but the coating film is in close contact with the core body and difficult to peel off at the application portions at both ends of the core body. In other words, it may be difficult to remove the completed belt from the core (see, for example, Patent Document 2).

In that case, if the thermal expansion coefficient of the resin film is smaller than the thermal expansion coefficient of the core body, extraction from the core body can be facilitated (see, for example, Patent Document 3). However, there are cases in which such a resin material cannot always be selected because of its characteristics, and it has been difficult to remove the resin material from the core (see, for example, Patent Document 4).
JP-A-9-85756 Japanese Patent Laid-Open No. 10-69183 Japanese Patent Laid-Open No. 2004-255708 JP 2005-122093 A

  An object of the present invention is to provide a method for producing an endless belt that can be easily extracted from a core body, and an endless belt obtained by the production method.

The object has been achieved by the present invention described below.
That is, the present invention
<1> The cylindrical core body is rotated in the circumferential direction around the axis of the cylindrical core body, and the first film-forming resin solution is allowed to flow down to the outer peripheral surface of the rotating cylindrical core body so as to be smooth. The first coating film forming step of smoothing by the forming member to form the first coating film, and the outer peripheral surface of the rotating cylindrical core body, on the outer side in the axial direction of the cylindrical core body of the first coating film, A second coating film forming step of forming a second coating film adjacent to the first coating film by flowing down the second film forming resin solution and smoothing by the smoothing member; and the first coating film and the second coating film A resin film forming step of forming a second resin film having a thermal expansion coefficient smaller than that of the first resin film, and the first resin film and the second resin film are cylindrical. A method for producing an endless belt, comprising: a step of extracting from the core.

<2> The method for producing an endless belt according to <1>, further including a second resin film removal step of removing the second resin film from the first resin film extracted from the cylindrical core.
<3> Both end portions in the axial direction are endless belts formed of a resin different from the central portion in the axial direction, and the thermal expansion coefficient of the resin in the both end portions in the axial direction is that of the central portion in the axial direction. An endless belt having a thermal expansion coefficient smaller than that of the resin.

  The present invention can provide a method for producing an endless belt that can be easily extracted from the core, and an endless belt obtained by the production method.

Hereinafter, the manufacturing method of the endless belt of the present invention will be described.
The process for producing an endless belt according to the present invention comprises rotating a cylindrical core body in the circumferential direction around the axis of the cylindrical core body, and forming a first film-forming resin on the outer peripheral surface of the rotating cylindrical core body. A first coating film forming step of forming a first coating film by flowing down the solution and smoothing with a smoothing member; and the cylindrical core of the first coating film on the outer peripheral surface of the rotating cylindrical core body A second coating film forming step of forming a second coating film adjacent to the first coating film by flowing down the second film forming resin solution on the outer side in the axial direction of the body and smoothing by the smoothing member; A resin film forming step of heating the coating film and the second coating film to form a first resin film and a second resin film having a thermal expansion coefficient smaller than that of the first resin film, and the first resin film And a extracting step of extracting the second resin film from the cylindrical core.

An example of the manufacturing method of the endless belt of the present invention will be described with reference to the drawings.
FIG. 1 shows a schematic view of an apparatus used in the method for producing an endless belt according to the present invention, wherein (A) is a side view and (B) is a front view. In FIG. 1, a resin solution 6 is held in a container 4 and sent out to a discharge port 5 by a pump 1. Further, pressurized air may be injected into the container 4 to extrude the resin solution 6, in which case a pump may not be necessary. The resin solution 6 is discharged (flowed down) from the discharge port 5 to the outer peripheral surface of the cylindrical core body 3 rotating in the direction of the arrow in the figure. At this time, the resin solution 6 flows down in a streak shape, and a streak-like coating film is formed, but is immediately smoothed by the smoothing member 2 pressed downstream, without leaving a spiral streak, A coating film 7 is formed. When the discharge port 5 is moved in the horizontal direction from one end of the core body to the other end as shown in FIG. 1B (from left to right in the figure) along with the application, it can be applied over the entire surface of the core body. During application, since the resin solution exists between the cylindrical core 3 and the smoothing member 2, they are not in direct contact with each other.

  The material of the cylindrical core 3 is not particularly limited, and examples thereof include metal materials such as iron-based alloys such as steel and stainless steel, and non-ferrous alloys such as aluminum, aluminum alloy, titanium, and titanium alloy. Of these, aluminum and its alloys are preferable. Further, surface treatment (plating, ion plating, etc.) may be performed from the viewpoint of preventing scratches.

The process for producing an endless belt according to the present invention includes a first coating film forming step of forming a first coating film by flowing a first film forming resin solution on the outer peripheral surface of the cylindrical core 3 and smoothing it with a smoothing member. Have Here, when the first film-forming resin solution is flowed down, the rotational speed of the cylindrical core 3 is preferably 20 to 300 rpm (more preferably 20 to 150 rpm).
Further, when the discharge port 5 moves with respect to the cylindrical core body 3, a coating film of the resin solution 6 that is the first film-forming resin solution is formed on the outer peripheral surface of the cylindrical core body 3. The horizontal moving speed of the discharge port 5 with respect to the cylindrical core 3 at this time is preferably 0.1 to 2.0 m / min (more preferably 0.5 to 1.5 m / min).

On the other hand, the discharge (downflow) amount of the resin solution 6 that is the first film-forming resin solution discharged from the discharge port 5 is preferably adjusted so that the obtained endless belt has a desired film thickness. The film thickness of a preferable endless belt is 25 to 150 μm (more preferably 50 to 100 μm). The pump 1 is preferably a Mono pump capable of discharging a constant amount without interruption. This pump is a rotary displacement type single-shaft eccentric screw pump, and the internal thread portion of the elastic material and the metallic external thread portion are fitted with high precision inside the pump to enable a constant volume movement. The advantage of this pump is that it can cope with a wide range of solution viscosities, and the flow rate can be freely controlled by controlling the male screw shaft rotation speed. The film thickness t of the coating film is in the range of 25 to 150 μm. It can be easily controlled.
Furthermore, in order to supply the solution from the container 4 to the dispensing mono pump 1, another mono pump may be installed. The pump adopts a pump with higher supply capacity than the dispensing mono pump, and supplies a larger amount than the dispensing mono pump.

  The endless belt manufacturing method of the present invention forms the first coating film by discharging the first film-forming resin solution onto the outer peripheral surface of the cylindrical core 3 as described above. The axial width of the cylindrical core 3 is preferably 0.5 to 10 cm longer than the intended endless belt (more preferably 1 to 5 cm).

  In the second coating film forming step, a second film forming resin solution is discharged as the resin solution 6 on the outer peripheral surface of the cylindrical core body 3 on the outer side in the axial direction of the cylindrical core body of the first coating film. Here, in the second coating film forming step, the rotational speed of the cylindrical core body 3, the horizontal movement speed of the discharge port 5, and the discharge (downflow) amount of the resin solution 6 as the second film forming resin solution are as described above. This is the same as the rotational speed of the cylindrical core 3 in the coating film forming step, the horizontal movement speed of the discharge port 5, and the discharge (downflow) amount of the resin solution 6 that is the first film-forming resin solution.

In the second coating film forming step, the second film forming resin solution is discharged to the outer side in the axial direction of the cylindrical core body 3 of the first coating film. It is necessary that the first coating film be adjacent to the first coating film on the outer side in the axial direction of the cylindrical core. Moreover, it is preferable that the axial width of the cylindrical core 3 in the flowing area is 1 to 5 cm (more preferably 2 to 4 cm).
On the other hand, the adjacent portions of the first coating film and the second coating film may be compatible with each other and partially enter the other region.

The endless belt manufacturing method of the present invention is characterized in that the thermal expansion coefficient of the second resin film is smaller than the thermal expansion coefficient of the first resin film. In addition, the thermal expansion coefficient of said 1st and 2nd resin film is measured by the method prescribed | regulated to JISK7197: 1991.
The difference between the thermal expansion coefficient of the second resin film and the thermal expansion coefficient of the first resin film is preferably 5 ppm or more (more preferably 5 to 20 ppm, still more preferably 5 to 10 ppm).

  The first film-forming resin solution and the second film-forming resin solution are not particularly limited as long as they are thermosetting resins that satisfy the relationship between the thermal expansion coefficients of the first and second resin films. First, a polyimide precursor solution, a polyamide-imide resin solution, an epoxy resin solution, and a triazine-based resin solution are exemplified. Among these, a polyimide precursor solution and a polyamide-imide resin solution are preferable, and a polyimide precursor solution is more preferable. The first film-forming resin solution and the second film-forming resin solution are preferably compatible with each other. From this point, the first film-forming resin solution and the second film-forming resin solution are the same resin. It is preferable that

  As the first and second film-forming resin solutions, the first film-forming resin solution is, for example, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (hereinafter referred to as “BPDA” as appropriate). In the case of a precursor solution of polyimide (hereinafter referred to as “A-type PI” as appropriate) consisting of 4,4′-diaminodiphenyl ether, the coefficient of thermal expansion is 28 ppm. As for those having a smaller coefficient of thermal expansion than this, PI composed of BPDA and p-phenylenediamine (thermal expansion coefficient 12 ppm, hereinafter referred to as “S-type” as appropriate) and pyromellitic dianhydride (hereinafter referred to as “ And a solution of PI (thermal expansion coefficient 20 ppm) precursor consisting of 4,4′-diaminodiphenyl ether. Since the S-type PI has a very low coefficient of thermal expansion, it is very preferable as a resin formed at the end.

When the obtained endless belt is used as a transfer member, a conductive substance is dispersed in the first film-forming resin solution in order to impart semiconductivity. Examples of the conductive material include carbon-based materials such as carbon black, carbon fiber, carbon nanotube, and graphite, metals or alloys such as copper, silver, and aluminum, tin oxide, indium oxide, antimony oxide, SnO ₂ —In ₂ O. ₃ Conductive metal oxides such as complex oxides. As described above, when the film contracts, the resistance value becomes uneven, but by preventing the contraction, the resistance value can be made uniform.

  In order to discharge the second film-forming resin solution to the axially outer side of the cylindrical core 3 of the first coating film, the solution is allowed to flow down from another discharge port before the first coating film is dried. It may be applied (the order may be reversed). Even if the first film-forming resin is other polyimide or polyamideimide, when S-type PI is applied to the end portion, the seam is mixed and united with each other, so that it is not easily broken.

  It is preferable to provide non-coated portions 3 ′ at both ends in the axial direction of the cylindrical core 3, but since there is no resin solution there, the smoothing member 2 comes into direct contact with the core and the core surface Damage to the surface of the smoothing member 2 is likely to occur, or the tip of the smoothing member 2 is worn. Therefore, the smoothing member 2 may be applied only at the time of application. As the method, there are a method of moving the smoothing member 2 back and forth or up and down, a method of rotating the fixed end of the smoothing member 2 and the like so that the distance of the smoothing member 2 to the core changes. Moreover, you may combine them.

  The smoothing member 2 is preferably a blade made of a metal having a thickness of about 0.1 to 1 mm made of a metal such as stainless steel or brass, or an elastic material such as fluororesin or polyethylene. The width of the smoothing member needs to be at least wider than the coating pitch (horizontal movement speed / core rotation speed), but streaks may be formed even if it is too wide. . The smoothing member 2 is preferably moved at the same speed as the discharge port 5.

  Moreover, in the manufacturing method of the endless belt of the present invention, as shown in FIG. 2, the cylindrical core body 3 is attached with flanges or the like on both sides of the core body and is rotated while holding the shaft through the shaft 20, or As shown in FIG. 3, the cylindrical core body 3 may be held with both sides of the cylindrical core 3 sandwiched between chucks 21 having only inclined surfaces. However, as shown in FIGS. 4 and 5, a step 23 fitted to the inner diameter of the cylindrical core 3 is provided in the middle of the inclined surface in that the cylindrical core 3 can be held and rotated without being deformed. The chuck 22 is preferably held by the chuck 22 having a step without having an inclined surface (the step 23 in the chuck 22 or 24 and the inner peripheral surface of the cylindrical core body 3 are fitted). By holding the cylindrical core body 3 by the chuck 22 or the chuck 24 having the step 23 shown in FIGS. 4 and 5, the cylindrical core body 3 is not deformed even if it expands. Further, the chuck 22 having an inclined surface is preferable as shown in FIG. 4 in that accuracy and time are not required for alignment when the chuck 24 is fitted to the inner peripheral surface of the cylindrical core 3.

It is preferable that the chuck 22 has an angle of 40 to 85 ° with respect to the axial direction of the cylindrical core body 3 (more preferably 55 to 70 °) with respect to the axial direction of the cylindrical core body 3. Moreover, it is preferable that the inclination located in the front-end | tip from the level | step difference 23 of the chuck | zipper 22 has an angle of 30-75 degrees with respect to the axial direction of the cylindrical core 3 (more preferably 45-60 degrees).
On the other hand, it is preferable that the chuck 24 has an angle of 40 to 85 ° with respect to the axial direction of the cylindrical core body 3 (more preferably 55 to 70 °). .

As the dimension of the step 23 in the chucks 22 and 24, the width of the cylindrical portion forming the step is preferably 10 mm or less, more preferably 3 mm or less.
The clearance between the inner peripheral surface of the cylindrical core 3 and the step 23 when the step 23 in the chuck 22 or 24 is fitted to the inner peripheral surface of the cylindrical core 3 is 0.05 to 0.2 mm. Is preferable (more preferably 0.05 to 0.1 mm).

  When the cylindrical core 3 is held by a chuck 22 or 24 having a step 23 fitted to the inner diameter of the cylindrical core 3 as shown in FIG. 4 or FIG. After the first and second coating films are formed, when the cylindrical core body 3 described later is moved to a drying apparatus and heat drying is performed, the core body is rotated horizontally so that the coating film does not hang downward. Preferably, after forming the coating film, it is preferable to put in the dryer with the chuck fitted.

  After at least the first coating film is smoothed by the smoothing member 2, the cylindrical core body 3 is moved to a drying device and dried by heating. At that time, it is preferable to carry out the process while rotating the core body horizontally so that the coating film does not hang downward. The rotation speed is preferably about 1 to 60 rpm, and the heating condition is preferably 90 to 170 ° C. for 20 to 60 minutes (when the first and second film-forming resin solutions are polyimide precursor solutions). At that time, the higher the temperature, the shorter the heating time, and the temperature may be raised stepwise or at a constant rate.

Thereafter, when the first and second film-forming resin solutions are polyimide (PI) precursor solutions, the first and second films are 250 to 450 ° C., preferably 300 to 350 ° C., and 20 to 60 minutes. A PI resin is formed by heating the precursor film to cause a condensation reaction (resin film forming step). At that time, the temperature may be increased stepwise. In this step, since the film is fixed, the core body may be oriented in any direction, and may not be rotated during heating.
On the other hand, when the first and second film-forming resin solutions are PAI resin solutions, films can be obtained only by drying the solvent.

  By extracting the first and second resin films formed by the resin film forming step from the cylindrical core body, both axial end portions are formed of a resin different from the axial central portion, and the axial direction The endless belt of the present invention is obtained in which the thermal expansion coefficient of the resin at both ends is smaller than the thermal expansion coefficient of the resin at the center in the axial direction.

When the film is extracted from the cylindrical core, if the coefficient of thermal expansion of the film is smaller than that of the cylindrical core, it is easy to extract the film. A film having an expansion coefficient smaller than that of the central portion is formed. If there is a coating with a smaller coefficient of thermal expansion at the end than the center, when the belt is formed, the coating will shift between the center and the end, and a slight gap will be formed between the cylindrical core at the end. Is done. Of course, when the coefficient of thermal expansion of the resin film at the end is smaller than that of the cylindrical core body, the gap between the cylindrical core body is formed larger.
From the gap between the slightly formed cylindrical core body, for example, by blowing pressurized air, a gap can be formed between the central core film and the cylindrical core body. The film is extracted from the cylindrical core (extraction process). The extraction can be easily performed.
The pressurized air is preferably blown using a nozzle having an opening diameter of 2 to 6 mm or a flat nozzle having an equivalent opening area and a pressure of 0.2 to 0.4 MPa at room temperature.

  The second resin film may remain if an endless belt is used as a fixing member, or may remain if a non-image area is wide at the end even if it is a transfer member. However, in the case of a transfer member that requires uniformity in electrical characteristics, the second resin film is cut off from the first resin film and removed (second resin film removal step). In addition, when attaching a meandering prevention rib to a belt edge part, you may attach a rib to that part, without cutting | disconnecting an edge part film | membrane with a small thermal expansion coefficient.

  In order to use the endless belt as a fixing belt, a fluororesin layer that is non-adhesive to toner is formed on the surface of a resin film such as a PI resin. The material is preferably a fluorine-based resin such as polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP). In addition, carbon powder may be dispersed in the non-adhesive resin layer in order to improve durability and electrostatic offset.

  In order to form the fluorine-based resin layer, a method in which the aqueous dispersion is applied to the surface of a resin film such as a PI resin and baked is preferable. Moreover, when the adhesiveness of a fluorine-type resin layer is insufficient, there exists a method of apply | coating and forming a primer layer beforehand on the surface of resin films, such as PI resin, as needed.

  In order to form a fluororesin layer on the surface of a resin film such as a PI resin, a heated resin film (belt) may be formed on the surface of the core and then applied. After applying the solution for drying and drying the solvent, or without completely drying the solvent, apply the fluororesin dispersion, and then heat to imide conversion completion reaction and firing treatment of the fluororesin layer May be performed simultaneously. In this case, the adhesiveness of the fluororesin layer may be strengthened even without the primer layer.

  When the endless belt of the present invention is used as a fixing belt, the thickness of the resin layer is preferably 25 to 150 μm, and the thickness of the fluororesin layer is preferably 10 to 40 μm.

Example 1
Using the coating apparatus shown in FIG. 1, the diameter of a type A PI precursor solution (trade name: Uimide, manufactured by Unitika, solid content concentration 18% by mass, coefficient of thermal expansion 28 ppm) having a viscosity of about 100 Pa · s at 25 ° C. It spin-coated on the cylindrical core 3 of 180 mm and length 600 mm. Specifically, carbon black (trade name: Special Black 4, manufactured by Degussa Huls) is mixed with the A-type PI precursor solution at a solid content mass ratio of 30.5%, and then an opposed collision type disperser (“Geanus” manufactured by Genus Corporation). PY "), and 5000 ppm of a surfactant (trade name: LS009, Enomoto Kasei) was added to form a coating solution. 800 ml thereof was put into the container 4, the MONO pump 1 was connected, and the discharge rate was adjusted to 50 g / min at a shaft rotation speed of 15 rpm.

As shown in FIG. 4, the chuck of the cylindrical core 3 has a conical shape with an outer diameter of 169.8 mm, a fitting length of 10 mm, and a height of 120 mm from the top to the bottom so that the stepped portion can be fitted to the inner diameter of the core. I used one.
Further, the smoothing member 2 (hereinafter referred to as “blade”) was formed by processing a stainless steel plate having a thickness of 0.4 mm into a width of 20 mm and a length of 70 mm and directly below the dispenser. Other coating conditions were applied as shown in Table 1 below.

  The A-type PI precursor solution (resin solution 6) is discharged toward the cylindrical core body, and after the A-type PI precursor solution makes 0.5 to 2 turns around the core body, the blade advances to make the A-type PI precursor. By contacting the solution and retreating the blade 50 mm at the same time as the discharge is completed, the PI precursor solution exists between the core and the blade during coating, so that the A-type PI precursor does not scratch the core and the blade. The body solution was smoothed.

  In this method, after applying the A-type PI precursor solution to the central portion 400 mm of the cylindrical core body, the S-type PI precursor solution (trade name: U varnish S, manufactured by Ube Industries, A solid content concentration of 18% by mass and a coefficient of thermal expansion of 12 ppm were discharged toward the cylindrical core in the same manner as the A-type PI precursor solution, and the blade was brought into contact therewith. Thereafter, while rotating the cylindrical core body at 10 rpm, the cylindrical core body was placed in a heating device at 120 ° C. and dried for 45 minutes. Next, the cylindrical core was made vertical and heated at 190 ° C. for 10 minutes, 250 ° C. for 30 minutes, and 320 ° C. for 30 minutes to form a PI resin film.

After the core had cooled to room temperature, a gap was formed at the end of the film, so that the belt could be easily pulled out from the core by blowing in pressurized air (room temperature, 0.2 MPa).
The obtained endless belt had an average film thickness of 80 μm and good quality without defects such as swelling and dents.

(Example 2)
Using a coating apparatus shown in FIG. 6, a type A PI precursor solution having a viscosity of about 100 Pa · s at 25 ° C. (trade name: Uimide, manufactured by Unitika, solid content concentration 18% by mass, coefficient of thermal expansion 28 ppm) has a diameter. It spin-coats to the cylindrical core 3 of 180 mm and length 600mm. That is, carbon black (trade name: Special Black 4, manufactured by Degussa Huls Co., Ltd.) was mixed with PI precursor solution at a solid content mass ratio of 30.5% by mass, and then dispersed by a counter collision type disperser, and a surfactant was added thereto. (Product name: LS009, Enomoto Kasei) was added at 5000 ppm to form a coating solution. 800 ml thereof was put into the container 4 and the Mono pump 1 was connected via the switching valve 9 to adjust the discharge rate to 50 g / min at a shaft rotation speed of 15 rpm. 6 further includes a container 11 in which the resin solution 10 is placed in the coating apparatus shown in FIG. 1, and the resin solution 10 flowing from the container 11 and the resin solution 6 flowing from the container 4 Is switched by the switching valve 9.

As shown in FIG. 4, the chuck of the cylindrical core 3 has a conical shape with an outer diameter of 169.8 mm, a fitting length of 10 mm, and a height of 120 mm from the top to the bottom so that the stepped portion can be fitted to the inner diameter of the core. I used one.
Further, 200 ml of S-type PI precursor solution (trade name: U varnish S, manufactured by Ube Industries, solid content concentration 18% by mass, coefficient of thermal expansion 12 ppm) was placed in the container 11 and connected to the MONO pump 1 via the switching valve 9. .

  On the other hand, the blade was processed by a stainless steel plate having a thickness of 0.4 mm to a width of 20 mm and a length of 70 mm, and was attached directly below the dispenser. Other coating conditions were applied as shown in Table 1 above.

After the S-type PI precursor solution in the container 11 is applied with a width of 40 mm at the start end, the A-type PI precursor solution in the container 4 is discharged toward the cylindrical core body 3 and the central portion of the cylindrical core body 400 mm After the A-type PI precursor solution makes 0.5 to 2 turns around the core body, the blade advances and comes into contact with the A-type PI precursor solution. Since the A-type PI precursor solution was present between the cylindrical core 3 and the blade at the time of coating, the PI precursor solution was smoothed without scratching the cylindrical core 3 and the blade. Furthermore, it switched to the switching valve 9, and apply | coated the S type PI precursor solution of the container 11 continuously by the width | variety of the end edge part 40mm, and formed the coating film 7 of the center part, and the coating film 8 of the edge part.
After coating, the core was rotated at 10 rpm and placed in a heating device at 120 ° C. and dried for 45 minutes. Next, the cylindrical core body 3 was placed vertically and heated at 190 ° C. for 10 minutes, 250 ° C. for 30 minutes, and 320 ° C. for 30 minutes to form a PI resin film.

After the cylindrical core 3 was cooled to room temperature, a gap was formed at the end of the film, so that the belt can be easily pulled out from the core by blowing in pressurized air (room temperature, 0.2 MPa). done.
The obtained endless belt had an average film thickness of 80 μm and good quality without defects such as swelling and dents.

(Comparative Example 1)
In Example 1, a PI resin film was formed in the same manner as in Example 1 except that the S-type PI precursor solution applied at a width of 40 mm at both ends was not applied. As a result, after the cylindrical core 3 is cooled to room temperature, no gap is formed at the end of the film and the sticking is strong, so that the pressurized air (at room temperature, 0.2-0. 4 MPa) could not be blown, and it was necessary to work and devise such as expanding the gap mechanically with PET resin having a thickness of about 100 μm and blowing pressurized air as a trigger. Further, when the gap was widened, the PI resin film was damaged or broken, and an endless belt having the desired quality could not be obtained.

(Comparative Example 2)
In Example 1, the A-type PI precursor solution applied to the central portion 400 mm was replaced with the S-type PI precursor solution, and the S-type PI precursor solution applied with a width of 40 mm at both ends was not applied. In the same manner as in Example 1, a PI resin film was formed. As a result, after the core has cooled to room temperature, a large gap is formed at the end of the coating, and the belt is easily pulled out by blowing pressurized air (room temperature, 0.2 to 0.4 MPa). I was able to. However, since the gap between the core and the core is large, the geometric shape of the obtained endless belt is unstable and the desired quality cannot be obtained.

It is the schematic of an example of the apparatus used for the manufacturing method of the endless belt of this invention, (A) is a side view, (B) is a front view. It is explanatory drawing of the conventional core which does not use a chuck | zipper. It is explanatory drawing of the chuck | zipper which has only an inclined surface. It is explanatory drawing of the chuck | zipper which has a level | step difference in the middle of an inclined surface. It is explanatory drawing of the chuck | zipper which does not have an inclined surface but has a level | step difference. It is the schematic of the apparatus used for the manufacturing method of the endless belt used in Example 2, (A) is a side view, (B) is a front view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Pump, 2 ... Smoothing member, 3 ... Core body, 3 '... Non-application part, 4 ... Container, 5 ... Discharge port, 6 ... Resin solution, 7... Central coating film, 8... End coating film, 9... Switching valve, 10. ... Container of resin solution for end application, 20... Axis, 21... Chuck having only inclined surface, 22... Chuck having a step in the middle of inclined surface, 23. ..Steps that fit into the inner diameter of the cylindrical core, 24... Chuck that has a step without an inclined surface

Claims (3)

  The cylindrical core body is rotated in the circumferential direction around the axis of the cylindrical core body, and the first film-forming resin solution is caused to flow down to the outer peripheral surface of the rotating cylindrical core body. The first coating film forming step for smoothing and forming the first coating film, and the outer peripheral surface of the rotating cylindrical core body, on the outer side in the axial direction of the cylindrical core body of the first coating film, Flowing down the film-forming resin solution, smoothing by the smoothing member, forming a second coating film adjacent to the first coating film, heating the first coating film and the second coating film A resin film forming step of forming a first resin film and a second resin film having a thermal expansion coefficient smaller than that of the first resin film, and the first resin film and the second resin film are formed into a cylindrical core. A method for producing an endless belt.   Furthermore, the manufacturing method of the endless belt of Claim 1 which has a 2nd resin film removal process of removing a 2nd resin film from the 1st resin film extracted from the said cylindrical core. Both end portions in the axial direction are endless belts formed of a resin different from the central portion in the axial direction,
An endless belt, wherein the thermal expansion coefficient of the resin at both ends in the axial direction is smaller than the thermal expansion coefficient of the resin at the central part in the axial direction.

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