JP2005231079A - Endless belt manufacturing method and cylindrical core body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an endless belt manufacturing method capable of manufacturing a plurality of endless belts by one coating work and hard to form a blister or the like in a manufacturing stage, and a cylindrical core body suitable for performing this manufacturing method. <P>SOLUTION: In the endless belt manufacturing method having a polyimide precursor coating film forming process, a polyimide resin film forming process and a polyimide resin film processing process, a cutting position prescribing process for prescribing a cutting position at the time of cutting processing is provided as the front or rear process of the polyimide precursor coating film forming process and the cutting of a polyimide film due to cutting processing is performed based on the cutting position to manufacture a plurality of the endless belts by the cutting process. Further, the cylindrical core body is used in this endless belt manufacturing method and positioning processing for prescribing the cutting position of the polyimide film is applied to a part of a roughened outer peripheral surface. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a manufacturing method of an endless belt that can be used in an image forming apparatus using an electrophotographic system such as a copying machine and a printer, and a cylindrical core used in the manufacturing method.

  In an image forming apparatus, a rotating body made of metal, plastic, or rubber is used for a photosensitive member, a charging member, a transfer member, and a fixing member. In some cases, these rotating bodies are preferably deformable, and for this, a belt made of a plastic film having a small thickness is used. In this case, if there is a seam in the belt, a defect due to the seam occurs in the output image. Therefore, an endless belt without a seam is preferable. As a material, polyimide resin is particularly preferable in terms of strength, dimensional stability, heat resistance, and the like.

  In order to produce an endless belt with polyimide resin, as described in Patent Document 1, a polyimide precursor solution is applied to the inner surface of a cylindrical body and dried while rotating, or as described in Patent Document 2. In addition, an inner surface coating method in which a polyimide precursor solution is developed on the inner surface of a cylindrical body is known. However, these methods of forming a film on the inner surface have the disadvantage that man-hours are required to remove the coating from the cylindrical body and place it on the outer mold when the PI precursor is heated.

As another method for producing a polyimide resin endless belt, for example, as described in Patent Document 3, the polyimide precursor solution is applied to the surface of the cylindrical core body by a dip coating method, dried, and heated and reacted. There is also a method of peeling the polyimide resin film from the cylindrical core. This method has the advantage that no man-hours are required for mounting on the outer mold.
However, the polyimide resin has a property that gas generation during the heating reaction is very large, and the endless belt of the polyimide resin after the heating reaction partially bulges like a lantern due to the generated gas. There is an easy problem. This is particularly noticeable when the thickness of the polyimide resin film is thicker than 50 μm. Examples of the gas generated during the heating reaction include a volatile gas of the residual solvent and water vapor generated during the reaction.

  In order to prevent the swelling, the present inventors have previously proposed a technique for roughening the surface of the core body and releasing gas as disclosed in Patent Document 4. However, this method allows gas to pass through a slight gap formed between the core body and the polyimide resin film and allows the gas to escape from the end portion. The road becomes long and difficult to escape, and it tends to swell, and the effect is insufficient. Therefore, in order to improve the production of endless belts, it has been difficult to produce a plurality of polyimide resin endless belts by a single coating operation using a long core.

  Further, as described in Patent Document 4 and Patent Document 5, there is a method of providing a hole (through hole) for allowing gas to escape on the side surface of the core body. However, when a hole is made in the side surface of the core, there is a problem that a protrusion corresponding to the hole is inevitably formed on the inner surface of the endless belt manufactured by coating. In addition, what is described in Patent Document 5 is that a film of a precursor or the like formed in advance is deposited on a cylindrical core body provided with a through-hole and heated to form a film. Therefore, it is considered that no protrusion is formed on the inner surface of the endless belt because it is not applied to the core itself.

From the above, in the method of applying to the surface of the cylindrical core, there was no method for producing a plurality of polyimide resin endless belts in a single application operation.
JP-A-57-74131 Japanese Patent Laid-Open No. 62-19437 Japanese Patent Laid-Open No. 61-273919 JP 2002-160239 A JP-A-10-258434

  In view of the above, an object of the present invention is to provide a method for producing an endless belt that can produce a plurality of endless belts in a single coating operation and that is less likely to swell in the production stage. Moreover, it aims at providing the cylindrical core body suitable for implementation of the manufacturing method.

As a result of intensive studies to solve the above problems, the present inventors have found that the problems can be solved by the following present invention, and have arrived at the present invention. That is, the present invention
<1> A polyimide precursor coating film forming step of forming a polyimide precursor coating film by applying a polyimide precursor solution to the outer peripheral surface side of a cylindrical core body having a roughened surface;
A polyimide resin film forming step of drying the polyimide precursor coating film to form a polyimide resin film;
The polyimide resin film is peeled from the cylindrical core, and a polyimide resin film processing step for obtaining an endless belt by performing a cutting process, and a method for producing an endless belt,
As a pre-process or post-process of the polyimide precursor coating film forming step, it has a cutting position defining step for prescribing a cutting position at the time of the cutting treatment,
The endless belt manufacturing method is characterized in that cutting by the cutting process is performed based on the cutting position, and a plurality of endless belts are manufactured by the cutting process.

  <2> The cutting position defining step is before the polyimide precursor coating film forming step, and the cutting position is defined by providing a positioning member on a part of the surface of the cylindrical core body. After the film formation step or after the polyimide resin film formation step, the positioning member is removed, and the cutting process is performed based on the removed portion. The production of the endless belt according to <1> Is the method.

  <3> The cutting position defining step is in front of the polyimide precursor coating film forming step, the cutting position is defined by providing a hole in a part of the cylindrical core, and the polyimide film is formed by the presence of the hole. The method for producing an endless belt according to <1>, wherein the cutting process is performed based on the formed holes.

  <4> The cutting position defining step is between the polyimide precursor coating film forming step and the polyimide resin film forming step, and the cutting position is defined by removing a part of the polyimide precursor coating film, The endless belt manufacturing method according to <1>, wherein the cutting process is performed based on the removed part.

<5> A cylindrical core used in the method for producing an endless belt according to any one of <1> to <3>, wherein a cutting position of the polyimide film is defined on a part of the roughened outer peripheral surface. The cylindrical core body is characterized by being subjected to a positioning process.
<6> The cylindrical core body according to <5>, wherein the positioning process is a process of providing a hole or a positioning member in a part corresponding to the cutting position.

  According to the present invention, since a plurality of endless belts can be manufactured simultaneously, an endless belt made of polyimide resin or the like can be manufactured at a lower cost. Further, the endless belt obtained by the production method of the present invention is less likely to swell at the production stage, has a uniform film thickness, and is suitable for an image forming apparatus such as an electrophotographic copying machine or a laser printer.

[1] Manufacturing method of endless belt:
The manufacturing method of the endless belt of the present invention includes a polyimide precursor coating film forming step of forming a polyimide precursor coating film by applying a polyimide precursor solution to the outer peripheral surface side of a cylindrical core body having a roughened surface. A polyimide resin film forming step of forming a polyimide resin film by drying the polyimide precursor coating film, a polyimide resin film processing step of peeling the polyimide resin film from the cylindrical core, and performing a cutting treatment to obtain an endless belt; Have

And, as a pre-process or a post-process of the polyimide precursor coating film forming process, it has a cutting position defining step for prescribing the cutting position in the cutting process, and the cutting by the cutting process is performed based on the cutting position. A plurality of endless belts are manufactured by the cutting process.
Thus, by defining the cutting position and performing the cutting process in the subsequent polyimide resin film processing step with the cutting position as a mark, a plurality of endless belts can be produced simultaneously. In addition, by appropriately setting the cutting position, a desired number of endless belts can be easily produced with a desired size.

The method for defining the cutting position in the cutting position defining step is not particularly limited, but it is preferable to apply the following first to third methods described later.
Hereinafter, taking a polyimide resin endless belt as an example, the endless belt manufacturing method of the present invention including the first method will be described in detail step by step. “Polyimide” may be abbreviated as “PI” as appropriate.

(First method)
First, the cylindrical core body to which the PI precursor or the like is applied can be appropriately selected and used from a known material that has been subjected to a roughening treatment, but a plurality of endless belts can be efficiently used, and In order to produce easily, it is preferable to use the cylindrical core of this invention mentioned later.

-Cutting position defining process-
In the first method of the present invention, first, a cutting member is defined by providing a positioning member on a part of the surface of the cylindrical core. The positioning member is not particularly limited as long as it becomes a mark for cutting during the cutting process. For example, when two endless belts are manufactured simultaneously, as shown in FIG. 1, an adhesive tape 12 as a positioning member is applied to a part of the surface of the cylindrical core at a position corresponding to the middle of the region where the endless belt is formed. paste. The size is arbitrary as long as it is in the range of 5 × 5 to 20 × 20 mm. If it is smaller than the above range, it may be difficult to apply or peel off, and if it is too large, the ineffective area of the film may increase. The number of adhesive tapes 12 is preferably about 4 to 12 in the circumferential direction, although it depends on the outer diameter of the cylindrical core and the size of the adhesive tape. If the number is small, the amount of gas passing may be insufficient, and if it is too large, the effort to remove may increase.

  The material of the base material of the adhesive tape 12 may be anything as long as it is not affected by the coating liquid, and polyester, nylon, polyimide, polypropylene and the like are preferable. When affixing the adhesive tape, a crease may be provided on one or both so that it can be easily peeled off later.

-PI precursor coating film formation process-
Next, a PI precursor solution is prepared. As the PI precursor, various known ones can be used. Further, two or more kinds of PI precursors may be mixed and used, or a plurality of acid or amine monomers may be mixed and copolymerized.

  Examples of the solvent for the PI precursor include aprotic polar solvents such as N-methylpyrrolidone, N, N-dimethylacetamide, and acetamide. The mixing ratio, concentration, viscosity, etc. of the PI precursor solution are appropriately selected according to the coating method.

In the PI precursor coating film forming step, the PI precursor solution is applied by a dip coating method in which the cylindrical core body is dipped in the PI precursor solution and pulled up, or the PI precursor solution is applied to the surface while rotating the cylindrical core body. A known method such as a flow coating method for discharging the film and a blade coating method for smoothing the coating film with a blade can be employed. In the above-described flow coating method or blade coating method, the coating portion is moved horizontally, so that the coating film is formed in a spiral shape, but the PI precursor solution is slow to dry, so the seam is naturally smooth.
In addition, "applying on a cylindrical core body" means apply | coating to the surface of the surface of the side surface of a cylindrical core body also including a column, and when there is a layer in this surface. Further, “rising the cylindrical core” refers to a relative relationship with the liquid level during application, and includes the case of “stopping the cylindrical core and lowering the coating liquid level”.

  In the PI precursor coating film forming step, when the PI precursor solution is applied by a dip coating method, the viscosity of the PI precursor solution is very high, and thus the film thickness may be too thick. In that case, a method of controlling the film thickness with an annular body as described in JP-A-2002-91027 can be applied.

A method for controlling the film thickness by the annular body will be described with reference to FIGS. FIG. 4 is a schematic configuration diagram showing an example of an apparatus used for a dip coating method in which the film thickness is controlled by an annular body. However, the figure shows only the main part for coating, and other devices are omitted.
As shown in FIG. 4, this dip coating method floats an annular body 5 having holes 6 larger than the outer diameter of the cylindrical core body 1 on the PI precursor solution 2 filled in the coating tank 3. 6 is a coating method in which the cylindrical core body 1 is immersed in the PI precursor solution 2 and then pulled up and applied.

  The material of the annular body 5 is selected from metals, plastics and the like that are not affected by the PI precursor solution 2. Moreover, a hollow structure may be used so that it can easily float, and legs or arms that support the annular body 5 may be provided on the outer peripheral surface of the annular body 5 or the coating tank 3 in order to prevent sinking.

The annular body 5 can be moved on the PI precursor solution 2 with a slight force, suspended on the solution, supported by the roll or bearing, and supported by the air pressure. , Etc., so that it can move freely in the horizontal direction.
Moreover, you may provide the fixing means which fixes the annular body 5 temporarily so that the annular body 5 may be located in the center part of the coating tank 3. FIG. When the fixing means is used, it is preferable that the fixing means is detachably arranged so that the annular body 5 can move freely when the cylindrical core body 1 is immersed and then pulled up.

  Since the film thickness of the coating film 4 is regulated by the gap between the outer diameter of the cylindrical core 1 and the diameter of the hole 6, the inner diameter of the hole 6 is adjusted by a desired film thickness. Moreover, since the film thickness of the coating film 4 is determined by the gap, the roundness of the holes in the annular body is important. When the roundness is low, the film thickness accuracy is lowered. Therefore, the roundness is preferably 20 μm or less, and more preferably 10 μm or less. Of course, it is optimal that the roundness is 0 μm, but it is difficult in processing.

  As shown in FIG. 4, the inner wall surface 6a of the hole 6 provided in the annular body 5 is a slanted surface that is an inclined straight line as shown in FIG. 4 if the lower part immersed in the PI precursor solution is wide and the upper part is narrow. Alternatively, a combined inclined surface as shown in FIG. 5 may be used. Further, it may be stepped or curved.

  When coating, the cylindrical core body 1 is immersed in the PI precursor solution 2, and then the cylindrical core body 1 is pulled up through the hole 6. The pulling speed is preferably about 0.1 to 1.5 m / min. The solid content concentration of the PI precursor solution preferable for this coating method is 10 to 40% by mass, and the viscosity is 1 to 100 Pa · s.

  When the cylindrical core body 1 is pulled up through the hole 6, the annular body 5 is free to move in the horizontal direction, so that the frictional resistance between the cylindrical core body 1 and the annular body 5 is constant in the circumferential direction. 5 moves. That is, when the cylindrical core body 1 is pulled up, if the gap between the annular body 5 and the cylindrical core body 1 is narrowed at a certain position, the frictional resistance is increased at the narrowed portion, whereas the friction is generated at the opposite side. Although the resistance becomes small and the frictional resistance temporarily becomes nonuniform, the annular body 5 can move freely, so that the frictional resistance is changed from the nonuniform state to the uniform state. 5 moves automatically. Therefore, the annular body 5 does not come into contact with the cylindrical core body 1. Therefore, the PI precursor coating film 4 having a uniform film thickness is formed on the surface of the cylindrical core body 1.

  Further, the coating apparatus used for the dip coating method includes a cylindrical core body holding means for holding the cylindrical core body, and, if desired, a first moving means and / or a coating tank for moving the holding means in the vertical direction. You may have the 2nd moving means to move to.

  In this way, by applying the dip coating method in which the film thickness is controlled by the annular body using the high-viscosity PI precursor solution, dripping of the coating film at the upper end of the cylindrical core due to gravity is reduced, The film thickness can be made uniform both in the direction and in the axial direction.

In the PI precursor coating film forming step, the annular coating method shown in FIG. 5 can also be applied. FIG. 5 is a schematic configuration diagram showing an example of an apparatus used for the annular coating method.
In FIG. 5, the difference from FIG. 4 is that an annular sealing material 8 having a hole slightly smaller than the outer diameter of the cylindrical core body is provided at the bottom of the annular coating tank 7. The cylindrical core body 1 is inserted through the center of the annular sealing material 8 and the PI precursor solution 2 is accommodated in the annular coating tank 7. Thereby, the PI precursor solution 2 does not leak. The cylindrical core body 1 is lifted up sequentially from the lower part to the upper part of the annular coating tank 7, and the coating film 4 is formed on the surface by inserting the annular body 5. Intermediate bodies 9 and 9 ′ that can be fitted to the cylindrical core body may be attached to the upper and lower sides of the cylindrical core body. The function of the annular body is the same as described above.
In such an annular coating method, the annular coating tank 7 can be made smaller than the dip coating tank 3 of FIG.

After the polyimide precursor coating film forming step as described above, the positioning member is removed. Since a hole is formed at the position where the positioning member is removed, it can be clearly distinguished from the region where the film is formed. Therefore, a plurality of endless belts can be manufactured with high accuracy by performing a cutting process described later based on the removed portion.
The positioning member may be removed before or after drying in the polyimide resin film forming step described later. Also in this case, after peeling, a hole corresponding to the size of the adhesive tape is formed in the film.

-PI resin film formation process-
In the PI resin film forming step, the PI precursor film is reacted by drying such as heating to form a PI resin film as follows.
First, for the purpose of removing most of the solvent present in the PI precursor coating film, heat drying is performed to such an extent that it does not deform even when the coating film is left standing. The heating condition is preferably 90 to 170 ° C. and 30 to 60 minutes. At that time, the higher the temperature, the shorter the heating time. In addition to heating, it is also effective to apply hot air. Heating may be increased stepwise or at a constant rate over time.
If the solvent is removed too much from the PI precursor coating film, the coating film does not yet maintain the strength as a belt, and there is a risk of causing cracks. Therefore, it is better to leave the solvent to some extent (specifically, 15 to 45% by mass in the PI precursor coating film).

After the drying, a PI resin film can be formed by heating and reacting the PI precursor coating film at a temperature of preferably 300 to 450 ° C., more preferably around 350 ° C. for 20 to 60 minutes. During the heating reaction, it is preferable to completely remove the residual solvent before reaching the final heating temperature. Specifically, the residual solvent is dried by heating at a temperature of 200 to 250 ° C. for 10 to 30 minutes. Subsequently, it is preferable to heat by gradually increasing the temperature stepwise or at a constant rate.
In the first method, since there is a hole in the film, gas can escape from there.

-PI resin film processing-
In the PI resin film processing step, after the heat reaction, the formed PI resin film is peeled off from the cylindrical core body and subjected to a cutting process to obtain an endless belt.
As shown in FIG. 6, both end portions of the extracted endless belt 10 are cut as unnecessary portions because the uniformity of the film thickness is inferior or there are many defects. Further, when two endless belts are manufactured at the same time, a hole or an inner surface has a protrusion between the target endless belts 10A and 10B, so that the endless belt is also cut as an unnecessary portion. In FIG. 6, a dotted line is a cutting location.
The endless belt may be further subjected to drilling (punching) processing, rib attaching processing, and the like as necessary.

(Second method)
In the second method of the present invention, the cutting position defining step is before the polyimide precursor coating film forming step, the cutting position is defined by providing a hole in a part of the cylindrical core, and the polyimide film is formed by the presence of the hole. The cutting process is performed on the basis of the holes formed. Other steps are as described in the first method.

  The hole also has a significance for letting gas escape. For example, when two endless belts are manufactured, a through hole is provided in a cylindrical core at a position corresponding to the middle of the region where the endless belt is formed. This will be described with reference to FIG.

FIG. 2 is a drawing for explaining the structure of the core body in the case of manufacturing two endless belts, where (a) is a perspective view and (b) is a cross-sectional view. In FIG. 2, the through hole 11 is provided in the cylindrical core body 1, and when an endless belt having the same width is manufactured, the position corresponds to the middle of the endless belt. If the size of the through-hole is too large, there is a possibility that the liquid enters and clogs, and if it is too small, the amount of gas passing is insufficient, so about 0.2 to 1.5 mm is preferable. The number of through holes 11 is preferably about 4 to 18 in the circumferential direction, although it depends on the outer diameter of the core. If the number is small, the amount of gas passing is insufficient, but it is not necessary to be too large. It is preferable to apply a mold release agent in the through hole.
Protrusions are formed on the inner surface of the endless belt applied to the through hole, but this is not a problem because it is cut as an unnecessary part. In the second method, since there is a hole in the film, gas can escape from there.

(Third method)
In the third method of the present invention, the cutting position defining step is between the polyimide precursor coating film forming step and the polyimide resin film forming step, and the cutting position is defined by removing a part of the polyimide precursor coating film. Thus, a cutting process is performed based on the removed part. Other steps are as described in the first method.

  For example, when two endless belts are produced after the PI precursor coating is formed and before the PI precursor coating is heated and dried, the PI corresponding to the middle of the endless belt in the region where the endless belt is formed. A part of the precursor coating film 4 is removed as shown in FIG. The size is preferably about 2 to 20 mm in diameter. If it is too small, the effect of escaping gas is insufficient, and if it is too large, the ineffective area of the film increases. The number of holes 13 depends on the outer diameter of the core and the size of the holes, but is preferably about 4 to 12 in the circumferential direction. If the number is small, the amount of gas passing is insufficient, and it is not necessary to be too large. As a method of removing a part of the coating film, there are a method of wiping with a waste cloth such as paper or cloth, a cotton swab, etc., or a suction with a dropper. In the third method, gas escapes from the through hole of the core body.

When the endless belt produced as described above is used as a transfer belt or a contact charging belt, a conductive substance is dispersed in the resin material as necessary. Examples of the conductive material include carbon black, carbon-based materials such as carbon beads granulated from carbon black, carbon fiber, carbon nanotube, and graphite; metals or alloys such as copper, silver, and aluminum; tin oxide, indium oxide, And conductive metal oxides such as antimony oxide and SnO ₂ —In ₂ O ₃ composite oxide.

  When an endless belt is used as a fixing member, it is effective to form a non-adhesive resin film on the belt surface in order to improve the releasability of the toner adhering to the surface. Examples of the non-adhesive resin coating material include polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), and tetrafluoroethylene-hexafluoropropylene copolymer (FEP). A fluororesin is preferred. In addition, carbon powder may be dispersed in the non-adhesive resin film in order to improve durability and electrostatic offset.

  In order to form the fluororesin coating, a method in which the aqueous dispersion is applied to the surface of the endless belt and baked is preferable. Thus, in order to form a fluorine resin film on the belt surface, an endless belt may be formed on the surface of the cylindrical core body and heated, and then these may be applied, but a PI precursor solution is applied. Then, after drying the solvent, a fluororesin dispersion may be applied, followed by heating to simultaneously complete the imide conversion reaction and the firing treatment of the fluororesin film. In this case, even if there is no primer layer, the adhesiveness of the fluororesin film may be strengthened.

  When an endless belt is used as a fixing member, the thickness is preferably in the range of 25 to 500 μm. The thickness of the primer layer provided as necessary is preferably in the range of 0.5 to 10 μm. The thickness of the fluororesin coating is preferably in the range of 4 to 40 μm.

  In the present invention, when pigments are contained in the coating film formed on the cylindrical core, their thickness is preferably measured as described below.

  When pigments are dispersed in a coating film or a film formed on a cylindrical core, they are not light transmissive, but the reflectance is extremely high because the film surface is smooth. Therefore, the film thickness of the coating film or the film is measured as shown in FIG. 7 while rotating the cylindrical core horizontally in order to prevent the stationary state and to measure efficiently. This can be done by the type displacement sensor 40.

  For example, when measuring the thickness of the coating film, first, the distance to the coating film 4 is measured by the laser displacement sensor 30. Thereafter, the distance to the surface of the cylindrical core body 1 is measured by the eddy current displacement sensor 40, and the film thickness can be calculated from the difference. Here, it is preferable to perform the measurement while horizontally rotating the cylindrical core. The reason is that the coating film immediately after the coating film forming step contains about 80% of a solvent that dissolves the polyimide precursor, and this This is because the solvent is difficult to evaporate at room temperature, and when it is left standing, dripping gradually occurs. On the other hand, since the film after drying is reduced to about 40%, it does not sag even if it is allowed to stand.

  Since the laser beam is reflected by the surface of the coating film 4 or the coating film surface, the laser displacement sensor 30 can measure the distance to the outer peripheral surface thereof. On the other hand, the eddy current sensor can measure the distance to the metal body regardless of the presence of the coating film 4 or the coating film. Therefore, by introducing an eddy current sensor, even if there is a shake when the cylindrical core body 1 is rotated horizontally or the cylindrical core body 1 itself is deformed, it can be dealt with by taking the difference between the two and measuring the film thickness. It becomes.

  As the laser displacement sensor 30 used here, for example, a laser wavelength of 670 nm and a laser spot diameter of an ellipse (short diameter 30 μm, long diameter 850 μm) can be used to measure the curved surface of the coating film or film. Use a glossy surface. On the other hand, the eddy current type displacement sensor 40 uses an all-metal type so that the material of the cylindrical core can be aluminum or stainless steel.

  As described above, by using the laser displacement sensor and the eddy current displacement sensor in combination, it becomes possible to measure the film thickness of the coating film or film on the surface of the cylindrical core body, and further, vibration occurs when the cylindrical core body is rotated horizontally. Even when the cylindrical core itself is deformed, the film thickness can be measured without being affected by these effects.

[2] Cylindrical core:
The cylindrical core body of the present invention is a cylindrical core body used in a method for manufacturing an endless belt, and a positioning process for defining a cutting position of a polyimide film is performed on a part of a roughened outer peripheral surface. Become.
When manufacturing a plurality of endless belts in a single coating operation, a plurality of endless belts will eventually be manufactured by cutting. If the cutting position is specified by the positioning process, it is desired with high accuracy. The number of endless belts can be obtained. Further, by providing a positioning member to be described later, it is possible to more effectively suppress defects such as swelling at the stage of manufacturing the endless belt.

The positioning process is preferably a process in which a hole or a positioning member is provided in a part corresponding to the cutting position.
As an aspect which provides a hole in a part corresponding to a cutting position, the example of the above-mentioned 2nd method can be mentioned specifically ,. Moreover, as an aspect which provides a positioning member, the example of the above-mentioned 1st method can be given.

  The cylindrical core is preferably made of a metal such as aluminum or stainless steel. In the present invention, the length of the cylindrical core body (the length in the axial direction) needs to be equal to or greater than the total width of the target number of endless belts in order to produce two or more endless belts. Furthermore, the length of the cylindrical core is equal to the number of target endless belts in order to secure a margin at the ineffective area generated at both ends and the cutting position for cutting the endless belt to obtain a plurality of endless belts. It is preferable that the length is about 10 to 40% longer than the length. The thickness of the cylindrical core is required to withstand mechanical and thermal strength, and varies depending on the material and outer diameter of the cylindrical core, but is preferably about 1 to 30 mm.

  In addition, in the above-described PI resin film forming step, the formed PI resin film may strongly adhere to the surface of the cylindrical core body, and therefore the surface of the cylindrical core body may be provided with releasability. preferable. For example, the surface of the cylindrical core is plated with chromium or nickel, coated with a fluorine resin or silicone resin, or a mold release agent is applied to the surface.

  As described above, the surface of the cylindrical core body is roughened to about Ra 0.2 to 2 [mu] m in order to prevent the swelling of the PI resin film at the stage of manufacturing the endless belt. Thereby, the residual solvent or water vapor generated from the PI resin can be discharged to the outside through a slight gap formed between the cylindrical core body and the PI resin film, thereby preventing swelling. For roughening the surface of the cylindrical core body, there are methods such as blasting, cutting, sandpapering and the like.

  Hereinafter, the present invention will be specifically described by way of examples. However, each example does not limit the present invention.

(Example 1)
-PI precursor coating film formation process-
Preparation of 20 mass% PI precursor solution A prepared by synthesizing BPDA (3 ′, 4,4′-biphenyltetracarboxylic dianhydride) and PDA (p-phenylenediamine) in N, N-dimethylacetamide did. The viscosity was 35 Pa · s.

An aluminum cylinder having an outer diameter of 68 mm and a length of 800 mm was prepared. This was blasted with spherical alumina particles to roughen the surface to Ra 1.0 μm. Furthermore, six through-holes with a diameter of 0.8 mm were formed at equal intervals in the circumferential direction at a central position of 400 mm from the end (cutting position defining step).
Next, a silicone release agent (trade name: KS700, manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to the surface and the inside of the through-hole, and baked at 300 ° C. for 1 hour to obtain a cylindrical core.

The PI precursor solution was applied onto the cylindrical core body by the annular coating method shown in FIG. As the annular body 5, an aluminum body having an outer diameter of 110 mm, a minimum inner diameter of 69.2 mm, and a height of 30 mm was produced. The inner wall was linearly inclined, the inclination angle with respect to the vertical line was 7 °, and the roundness of the inner diameter was 13 μm.
Intermediate bodies 9 and 9 ′ were attached to the top and bottom of the cylindrical core body 1. The intermediate body 9 was passed through an annular coating tank 3 ′ having an inner diameter of 150 mm and a height of 50 mm, to which a polyethylene annular sealing material 8 having a hole having an inner diameter of 66 mm was attached. The PI precursor solution 2 was placed in the annular coating tank 3 ′, the annular body 5 was disposed, and the cylindrical core body 1 was raised at 0.5 m / min for coating. Thereby, a PI precursor coating film 4 having a wet film thickness of about 600 μm was formed on the surface of the cylindrical core body 1.

-PI resin film formation process-
Next, the cylindrical core was horizontal and rotated at 20 rpm, followed by drying at room temperature for 5 minutes, followed by heat drying at 80 ° C. for 20 minutes and at 100 ° C. for 1 hour. Thereby, a PI precursor coating film having a thickness of about 150 μm was obtained. Next, the cylindrical core was once cooled to room temperature. At this time, the PI precursor coating film contracted by about 1% in the axial direction.

  Thereafter, a polyester tape having a width of 20 mm was wound around one end of the PI precursor coating film to perform a coating treatment. Next, a PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer) dispersion water-based paint (trade name: 710CL, manufactured by Mitsui Dupont Fluoro Chemical Co., Ltd.) was placed in a coating tank having an inner diameter of 90 mm and a height of 900 mm. The cylindrical core body was immersed with the covering portion on the bottom and perpendicular to the liquid surface, leaving the upper polyimide precursor coating film by 5 mm. Subsequently, it pulled up at a speed of 0.2 m / min to form a PFA coating film. After the pulling up, the polyester tape was removed and dried at 80 ° C. for 10 minutes. Furthermore, it was heated at 150 ° C. for 20 minutes, then at 200 ° C. for 20 minutes, and then heated at 380 ° C. for 30 minutes to form a PI resin film, and the PFA coating film was baked.

-PI resin film processing-
After cooling to room temperature, the film was removed from the core. This had a 30 μm-thick PFA layer on an endless belt of 75 μm-thick PI resin, and the film did not swell. In addition, the inner surface of the PI resin was a rough surface of Ra 0.8 μm, and a small protrusion was seen at the center portion corresponding to the through hole provided in the core body. Since this method does not make a hole in the PI resin film, it is suitable for overcoating.
Next, as shown in FIG. 6, endless belts 10A and 10B were obtained by cutting about 30 mm from both ends of endless belt 10 and about 10 mm from the center side.
This endless belt could be suitably used as an electrophotographic fixing belt.

(Example 2)
-PI precursor coating film formation process-
Carbon black (trade name: Special Black 4, manufactured by Degussa Huls Co., Ltd.) was mixed in the same PI precursor solution A as in Example 1 at a solid mass ratio of 23%, and then dispersed by a counter collision type disperser. Furthermore, in order to improve the coatability of the coating film, a silicone leveling agent (trade name: DC3PA, manufactured by Dow Corning Tore Silicone) was added to a concentration of 500 ppm to obtain PI precursor solution B.

  Separately, an aluminum cylinder having an outer diameter of 366 mm and a length of 900 mm was prepared, and the surface was roughened to Ra 1.0 μm by blasting with spherical alumina particles. On the surface, a silicone release agent (same as in Example 1) was applied, and baked at 300 ° C. for 1 hour to obtain a cylindrical core.

  Using the PI precursor solution BB, a PI precursor coating film was formed by the annular coating method shown in FIG. As the annular body 5, an aluminum body having an outer diameter of 420 mm, a minimum inner diameter of 367.1 mm, and a height of 50 mm was produced. The inner wall was linearly inclined, the inclination angle with respect to the vertical line was 7 °, and the roundness of the inner diameter was 15 μm.

  The cylindrical core body 1 was attached with an annular sealing material 8 made of polyethylene having a hole with an inner diameter of 166 mm on the bottom surface, and passed through an annular coating tank 7 (inner diameter 450 mm, height 100 mm). The PI precursor solution 2 was placed in the annular coating tank 7, the annular body 5 was disposed, and the cylindrical core body 1 was raised at 0.4 m / min for coating. Thereby, the PI precursor coating film 4 having a wet film thickness of about 500 μm was formed on the surface of the cylindrical core.

-PI resin film formation process-
The cylindrical core body on which the PI precursor coating film was formed was leveled and held in a rotatable state. Next, as shown in FIG. 3, the central portion of the PI precursor coating film 4 was scraped with a small sponge, and six holes 13 having a diameter of about 5 mm were formed (cutting position defining step). After drying at room temperature for 5 minutes, it was dried by heating at 80 ° C. for 20 minutes and 130 ° C. for 30 minutes while rotating at 6 rpm, and then the cylindrical core was cooled to room temperature. Thereby, a PI resin coating film having a thickness of about 150 μm was obtained. Then, the cylindrical core body was made vertical, and the reaction was performed by heating at 200 ° C. for 30 minutes and at 340 ° C. for 30 minutes to form a PI resin film.

-PI resin film processing-
After cooling to room temperature, the PI resin film was extracted from the cylindrical core. This PI resin film was uniform with a film thickness of 75 μm.
As shown in FIG. 6, the obtained PI resin film 10 was obtained by cutting unnecessary portions by 30 mm from both ends and further cutting by approximately 20 mm from the center side to obtain endless belts 10A and 10B.
This endless belt could be suitably used as an electrophotographic transfer belt.

(Example 3)
-PI precursor coating film formation process-
As shown in FIG. 2, polyester adhesive tapes 12 cut to 5 × 10 mm were attached to the central portion of the cylindrical core body of Example 2 at six locations in the circumferential direction (cutting position defining step). Subsequently, a PI precursor coating film was formed in the same manner as in Example 2.

-PI resin film formation process-
After the PI precursor coating was dried, the polyester adhesive tape was removed from the cylindrical core by tweezers. As a result, a hole of about 5 × 10 mm was formed in the PI precursor coating. At that time, care was taken not to tear the PI precursor coating film. Otherwise, a PI resin film was formed in the same manner as in Example 2. Also by this method, the same endless belt as in Example 2 could be obtained.

(Comparative Example 1)
The central portion of the endless belt on the cylindrical core has a diameter of 20 to 30 mm and a height that is the same as in Example 1 except that two endless belts were prepared without providing through holes in the cylindrical core. Several blisters of several mm occurred, which was inferior to the endless belts of Examples 1 to 3.

In addition, the film thickness of the coating film and the film was measured as follows. That is, an apparatus provided with a laser displacement sensor (manufactured by Keyence, product name; LK-035) and an eddy current displacement sensor (manufactured by Keyence, product name: EX-022) while the cylindrical core body is leveled and rotated at 6 rpm. Each distance from the core was measured at, and the film thickness was measured from the difference.
Further, the laser wavelength of the laser displacement sensor was 670 nm, and the laser spot diameter was an ellipse (minor axis 30 μm, major axis 850 μm).

It is explanatory drawing of the cylindrical core used for this invention. It is a schematic block diagram which shows the other embodiment of this invention. It is a schematic block diagram which shows other embodiment of this invention. It is a schematic block diagram which shows the coating method. It is a schematic block diagram which shows the other application | coating method. It is explanatory drawing which shows the cutting | disconnection location of a film | membrane. It is a schematic block diagram which shows the apparatus which measures the film thickness of the polyimide precursor coating film or film | membrane on a cylindrical core.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Cylindrical core body 2 ... Polyimide precursor solution 3 ... Coating tank 4 ... Polyimide precursor coating film 5 ... Ring body 6 ... Ring hole 7 ... Ring coating Tank 8 ... annular seal material 9, 9 '... intermediate 10 ... endless belt 11 ... through hole 12 ... adhesive tape 13 ... hole 30 ... laser displacement sensor 40 ...・ Eddy current displacement sensor

Claims (6)

A polyimide precursor coating film forming step of forming a polyimide precursor coating film by applying a polyimide precursor solution to the outer peripheral surface side of the cylindrical core body having a roughened surface;
A polyimide resin film forming step of drying the polyimide precursor coating film to form a polyimide resin film;
The polyimide resin film is peeled from the cylindrical core, and a polyimide resin film processing step for obtaining an endless belt by performing a cutting process, and a method for producing an endless belt,
As a pre-process or post-process of the polyimide precursor coating film forming step, it has a cutting position defining step for prescribing a cutting position at the time of the cutting treatment,
A method of manufacturing an endless belt, wherein cutting by the cutting process is performed based on the cutting position, and a plurality of endless belts are manufactured by the cutting process.   The cutting position defining step is before the polyimide precursor coating film forming step, and the cutting position is defined by providing a positioning member on a part of the surface of the cylindrical core body, and the polyimide precursor coating film forming step The manufacturing method of the endless belt according to claim 1, wherein the positioning member is removed after the polyimide resin film forming step, and the cutting process is performed based on the removed portion.   The cutting position defining step is before the polyimide precursor coating film forming step, and the cutting position is defined by providing a hole in a part of the cylindrical core, and is formed in the polyimide film due to the presence of the hole. The method for manufacturing an endless belt according to claim 1, wherein the cutting process is performed based on a hole.   The cutting position defining step is between the polyimide precursor coating film forming step and the polyimide resin film forming step, and the cutting position is defined by removing a part of the polyimide precursor coating film and removed. The method of manufacturing an endless belt according to claim 1, wherein the cutting process is performed based on the part.   It is a cylindrical core used for the manufacturing method of the endless belt in any one of Claims 1-3, Comprising: The positioning process for prescribing the cutting position of a polyimide film in a part of roughened outer peripheral surface A cylindrical core body characterized by being applied.   6. The cylindrical core according to claim 5, wherein the positioning process is a process of providing a hole or a positioning member in a part corresponding to the cutting position.

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