JP2004094042A - Endless belt made of polyimide resin and its manufacture method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an endless belt which hardly meanders even when it is driven to be rotated and which is restrained from being wrinkled due to meandering, and to provide its manufacture method. <P>SOLUTION: The polyimide resin endless belt is constituted so that its center part in a width direction is thinner than both ends in terms of thickness. It is constituted so that the center part in the width direction is swollen to the outside further than the ends when it is stretched and laid by two rolls. Furthermore, the manufacture method of the polyimide resin endless belt includes a release layer forming stage for forming a release layer by performing surface roughening work to the surface of a core body, a precursor coating film forming stage for forming a polyimide precursor coating film by applying a polyimide precursor solution to the surface of the release layer and drying it, and a polyimide coating film forming stage for forming a polyimide coating film by performing heating after providing a gap between the polyimide precursor coating film and the core body at both ends of the polyimide precursor coating film. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an endless polyimide resin belt used for a photosensitive member, a charged member, a transfer belt, a fixing belt, and the like in an image forming apparatus such as an electrophotographic copying machine or a laser printer, and a method for manufacturing the same.
[0002]
[Prior art]
A rotating body made of metal, plastic, or rubber is used for a photoconductor, a charged body, a transfer belt, and a fixing belt in an image forming apparatus such as an electrophotographic copying machine or a laser printer. Here, in order to reduce the size or improve the performance of the apparatus, the rotating body is preferably deformable in some cases, and a thin resin belt is used for this. In this case, if there is a seam in the belt, a defect due to the seam occurs in the output image. Therefore, it is preferable that there is no seam. From such a viewpoint, an endless belt is used.
As a material of the endless belt, a polyimide resin is preferable in terms of strength, dimensional stability, heat resistance and the like.
[0003]
There are various publications regarding fixing devices using endless belts (for example, see Patent Documents 1 and 2).
As a transfer device using an endless belt, for example, there is a device that transfers a toner image from a photoconductor to a sheet while stretching and rotating a transfer belt around a plurality of rolls (for example, see Patent Document 3).
For a transfer fixing device using an endless belt, for example, a toner image is transferred from a photoconductor onto an endless belt while the endless belt is stretched around a plurality of rolls and rotated, and then heated to transfer the toner image onto paper. (See, for example, Patent Document 4).
[0004]
Incidentally, the endless belt may meander when driven to rotate. If the meandering occurs, it is not preferable because not only normal image formation cannot be performed, but also unrecoverable wrinkles may occur on the belt.
In order to prevent meandering, it is only necessary to increase the accuracy of the rotary driving device, but there is a disadvantage that the cost is increased.
[0005]
In order to prevent meandering, for example, a polyimide resin belt having a peripheral length difference between an end and a central portion is disclosed, but it is not possible to individually set the peripheral length difference according to the personality of the rotary driving device. In addition to the fact that it is difficult in practice, in the case of a method of producing a polyimide resin belt on a core, it is also difficult to remove the belt from the core (for example, see Patent Document 5).
[0006]
On the other hand, as a method of manufacturing a polyimide resin endless belt, for example, a centrifugal molding method in which a polyimide precursor solution is applied to the inner surface of a cylindrical body and dried while rotating (for example, see Patent Document 6), There is an inner surface coating method for developing a precursor solution (for example, see Patent Document 7). However, in these inner surface coating methods, it is necessary to dry the solvent of the polyimide precursor solution from the inside of the cylindrical body.
[0007]
As another manufacturing method of the endless belt, for example, there is a method in which a polyimide precursor solution is applied to the surface of a core by a dip coating method, dried, heated, and then the polyimide resin film is peeled from the core (for example, And Patent Document 8). In this method, since the solvent is dried from the outer surface of the core, the drying time is advantageously reduced, and the shape of the outer surface of the core is molded into the inner surface of the endless belt.
[0008]
Here, as a solvent of the polyimide precursor solution, an aprotic polar solvent is used, and all aprotic polar solvents have a property that a boiling point is high and drying is very slow. Further, since the polyimide resin film has a low gas permeability, a part thereof is likely to remain even when the solvent is dried.
[0009]
In the method of peeling after forming the polyimide resin film on the core body surface, in the heating step of the film, the residual solvent or water generated at the stage where the imidization reaction proceeds, the inside of the film or the core body and the film If it stays in the middle, it expands by heat to become a high-pressure gas, and the polyimide resin film may be partially expanded and deformed. This is particularly remarkable when the film thickness exceeds 50 μm.
[0010]
[Patent Document 1]
JP-A-5-150679
[Patent Document 2]
JP-A-8-262903
[Patent Document 3]
JP-A-10-218850
[Patent Document 4]
JP-A-10-20538
[Patent Document 5]
Japanese Patent No. 2625021
[Patent Document 6]
JP-A-57-74131
[Patent Document 7]
JP-A-62-19437
[Patent Document 8]
JP-A-61-273919
[0011]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION An object of the present invention is to provide a polyimide resin endless belt which is hardly meandered even when driven to rotate and in which wrinkles due to meandering are suppressed, and a method for manufacturing the same.
[0012]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present inventors have found that the problems can be solved by the present invention described below. That is, the present invention
<1> A polyimide resin endless belt, characterized in that the thickness at the center in the width direction is smaller than that at both ends.
<2> The polyimide resin endless belt, wherein the thickness of both end portions is 1.05 to 1.2 times the thickness of the central portion.
[0013]
<3> A polyimide resin endless belt characterized in that, when stretched by two rolls, a central portion in a width direction swells outward from an end portion.
[0014]
<4> The method for producing a polyimide resin endless belt according to <1> to <3>, wherein the surface of the core body is roughened to form a release layer, A precursor film forming step of applying a polyimide precursor solution to the mold layer surface and drying to form a polyimide precursor film, and forming a gap between the polyimide precursor film and the core at both ends of the polyimide precursor film. A polyimide film forming step of forming a polyimide film by performing a heat treatment after providing the polyimide resin endless belt.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the polyimide resin endless belt (hereinafter, sometimes simply referred to as “endless belt”) of the present invention and a method for producing the same will be described in detail with reference to the drawings.
[0016]
<Polyimide resin endless belt>
As shown in the sectional view of FIG. 1, the first polyimide resin endless belt of the present invention has a central portion h in the width direction (arrow X direction) of the endless belt. ₁ Is the end thickness h ₂ And h ₂ 'It's thinner.
Edge thickness h ₂ And h ₂ 'To the center ₁ By increasing the thickness of the endless belt, the strength against bending of the end portion is increased, and even when the endless belt runs and is pressed against one side due to a deviation, the end portion can hold the end portion and suppress meandering. be able to. In addition, wrinkles occur from the point where the endless belt is pressed to one side as a starting point. However, since the first endless belt of the present invention has a strong end portion, no wrinkling starting point occurs.
[0017]
Here, the “thickness of the central portion” refers to the thickness at a position L / 2 from the end, where L is the width of the endless belt at the center in the driving direction when stretched.
Further, the thickness of the endless belt usually used is 25 to 150 μm, but from the viewpoint of further increasing the strength against bending of the end, in the present invention, the film thickness of the end is 5 to 5 mm more than the thickness of the center. Preferably, it is 20% thicker (the thickness of both ends is 1.05 to 1.2 times the thickness of the central portion). If it is thinner than 1.05 times the thickness of the central part, it may not be possible to sufficiently increase the bending strength of the ends, and if it is thicker than 1.2 times, cracks may be formed from the ends and breaks are likely to occur. May be.
In the preferred range, when the thicknesses of the end portions are different from each other, the thickness of the thinner end portion is used as a reference.
[0018]
In the first polyimide resin endless belt of the present invention, the manner in which the thickness changes from the center to both ends is not particularly limited as long as the average thickness is in the range of 25 to 150 μm.
For example, as shown in FIG. 1 (a), the thickness may be gradually increased near both ends, and as shown in FIG. May be increased.
However, when the inner diameter of the endless belt is large (for example, 150 mm or more), the thickness increase near both ends is small, and when the inner diameter is small (for example, less than 150 mm), the thickness increases near both ends. Preferably, the amount is large.
[0019]
As shown in FIG. 2, when the polyimide resin endless belt 21 is stretched around two rolls 24a and 24b, the second polyimide endless belt of the present invention is located at a central portion from the end 22 of the belt in the width direction. 25 bulges outward (in the direction of arrow A).
As described above, when the central portion 25 is bulged outward, when the endless belt is stretched over a plurality of rolls, the pulling force toward the end portion becomes stronger than that of the central portion 25, so that the center portion 25 is allowed to travel and be offset. Even if it is attempted to be generated, not only is it hard to be deviated, but also the starting point of wrinkles is hardly generated.
Conversely, when the central portion 25 protrudes inward, the offset is further emphasized, and the meandering is easily performed. Further, even if the ends of the rolls 24a and 24b have flanges for preventing deviation, the rolls 24a and 24b may get on the flanges.
[0020]
If a crown-shaped roll having a swelling at the center in the axial direction corresponding to the swelling of the center 25 is used as the rolls 24a and 24b for rotating and driving the endless belt, meandering can be made more difficult to occur.
[0021]
The protruding height of the central portion 25 depends on the use and size of the endless belt to be used, but the height (h) from any one of the end portions 22 to the top of the central portion 25. ₃ ), Preferably from 3 to 30 mm, more preferably from 5 to 20 mm.
If it is less than 3 mm, the pulling force applied to the end is not sufficient, and the effect of suppressing meandering may not be exhibited. Rotation may be hindered.
[0022]
In the second polyimide resin endless belt, as described above, when the polyimide resin endless belt is stretched over two rolls, the central portion is bulged outward in the width direction, and Like one polyimide resin endless belt, the thickness at the center in the width direction of the endless belt may be smaller than the thickness at both ends. By adopting such an aspect, the strength against bending of the end portion is further increased, and the occurrence of meandering and wrinkles during traveling can be effectively suppressed.
[0023]
<Production method of polyimide resin endless belt>
The polyimide resin endless belt of the present invention is manufactured as follows. That is, first, the surface of the core body is subjected to a roughening process, and then a release layer is formed (release layer forming step). After the release layer is formed, a polyimide precursor solution is applied to the surface and dried to form a polyimide precursor film (precursor film forming step). Thereafter, at both ends of the polyimide precursor film, a gap is provided between the polyimide precursor film and the core, and a heat treatment is performed to form a polyimide film (polyimide film forming step). After the polyimide resin film is formed, the polyimide resin endless belt of the present invention is manufactured by removing it from the core and subjecting it to various known treatments as necessary.
[0024]
In the production method of the present invention, particularly in the polyimide film forming step, by providing a gap between the polyimide precursor film and the core, when heating the polyimide precursor film, uneven in the axial direction of the core. Shrinkage occurs due to shrinkage. As is well known, polyimide resin undergoes large shrinkage during heating. Therefore, at the end of the endless belt, if a gap is formed between the core and the core, the polyimide precursor film can be freely shrunk, and the shrinkage in the axial direction of the core is larger than that in the center. Become. As a result, the film thickness is larger at the end than at the center.
At the end of the endless belt, since the polyimide precursor film can now freely shrink, not only the shrinkage rate, but also the shrinkage force is freely exerted. The part shrinks and the central part expands.
On the other hand, by roughening the surface of the core body, it also has a function of releasing gas generated when the polyimide precursor coating film is heated, and an endless belt that does not expand when heated can be obtained.
Hereinafter, the method for producing the endless belt of the present invention will be described in more detail.
[0025]
First, as the core, it is preferable to use a metal such as aluminum, zinc, copper, stainless steel, and nickel. In the case of aluminum, zinc, or copper, it may be plated with chromium or nickel so that the surface is not easily damaged.
[0026]
The surface of the core is roughened. Examples of the method include blasting and honing, in which powder is sprayed, and cutting or scoring, in which a processing member such as a metal blade, a metal file, a metal brush, or sandpaper is rubbed on the surface of the core body. During processing, the processing member is moved in the axial direction while rotating the core. The processing method / condition varies depending on the outer diameter of the core, the desired roughness, or the roughened shape.
[0027]
In the case of the production method of the present invention, the surface roughness of the core body is preferably Ra 0.5 to 3.0 μm. If the surface roughness Ra is smaller than 0.5 μm, the polyimide resin film is likely to swell in the polyimide resin film forming step. If Ra is larger than 3.0 μm, air bubbles easily enter the polyimide precursor during application or drying of the polyimide precursor, which is not preferable. Also, due to the roughening of the core body surface, when the film shrinks when the polyimide resin is heated, unevenness between the film and the core body surface occurs, and a slight gap is formed between the polyimide resin film and the core body surface. Thus, the residual solvent or water can be effectively released.
Here, Ra indicates an arithmetic average roughness defined by JIS, which is one of the scales of roughness, and is measured by a stylus type surface roughness measuring device (for example, Surfcom 1400A, manufactured by Tokyo Seimitsu Co., Ltd.). be able to. The measurement conditions are based on JIS B0601-1994, and it is preferable that the evaluation length Ln = 4 mm, the reference length L = 0.8 mm, and the cutoff value = 0.8 mm (the measurement conditions are limited to these. Is not something).
[0028]
The effect of the roughness of the surface of the endless belt depends on its thickness. The thinner the thickness, the greater the influence of the surface of the endless belt from the surface of the core. The surface roughness of the endless belt varies depending on the purpose of use. However, if Ra exceeds 0.3 μm, problems such as image defects are likely to occur, and the surface roughness Ra of the endless belt is preferably 0.3 μm or less.
In consideration of the surface roughness of the endless belt, when the film thickness is 25 μm to 50 μm, the core body surface roughness Ra is preferably in the range of 0.5 μm to 1.5 μm. Further, when the film thickness is 51 μm to 150 μm, the amount of generated gas increases and the gas permeability decreases, so that it is necessary to increase the surface roughness of the core body. The surface roughness Ra is preferably in the range of 0.5 to 3.0 μm. Thus, the surface roughness of the core body can be determined by the required thickness of the endless belt and the back surface roughness of the endless belt.
[0029]
(Release layer forming step)
Also, in order to improve the releasability of the polyimide resin belt from the core, the surface of the core is coated with a fluorine resin or a silicone resin, or a release agent made of silicone oil or the like is applied to form a release layer. I do. The thickness of the release layer is preferably about 0.01 μm to 10 μm.
[0030]
(Precursor film formation step)
After forming the release layer, a polyimide precursor solution is applied to the surface.
The polyimide resin precursor is synthesized by dissolving an acid anhydride and a diamine in an aprotic polar solvent, and a conventionally known polyimide resin can be used.
The solvent is a conventionally known aprotic polar solvent such as N-methylpyrrolidone, N, N-dimethylacetamide, acetamide, N, N-dimethylformamide and the like. The concentration, viscosity and the like of the solution are appropriately selected.
[0031]
As a method of applying the polyimide precursor solution, a dip coating method in which the core is immersed in the polyimide precursor solution and pulled up, a flow coating method in which the core is horizontally rotated and the solution is discharged onto the surface thereof, and a blade is used in this case. A blade coating method of metalling the film by using a known method can be adopted. In the above-mentioned flow coating method or blade coating method, the coating is formed in a spiral shape by horizontally moving the coating portion in the axial direction of the core, but the solvent of the polyimide precursor solution is slow to dry at room temperature because it is slow. Spiral seams are naturally smoothed.
[0032]
In addition, since the polyimide precursor solution has a very high viscosity and the amount of adhesion is too large in the dip coating method, as disclosed in JP-A-2002-91027, a circular shape larger than the outer diameter of the core body is used. It is preferable to adopt a method in which the annular body provided with the above holes is placed on the polyimide precursor solution in a freely movable state, and the core is relatively raised from the solution through the holes of the annular body.
[0033]
The above coating method will be described with reference to the drawings. FIG. 3 is a schematic view of the coating apparatus from which the peripheral portion is omitted.
In the present invention, “applying on the core” means to apply on the surface of the core and, if the surface has a layer, on the layer.
Further, “elevating the core” refers to a relative relationship with the coating liquid level, and includes a case where the core is fixed and the coating liquid level is lowered.
[0034]
In FIG. 3, the polyimide precursor solution 32 is put in a coating tank 33, the core 31 is immersed in the coating tank 33, and then raised to perform coating, whereby a coating film 34 is formed. On the polyimide precursor solution 32, an annular body 35 provided with a circular hole 36 larger than the outer diameter of the core body 31 is installed in a freely movable state. Since the wet thickness of the coating film is determined by the gap between the core 31 and the hole 36, the inner diameter of the hole 36 is set in consideration of the desired film thickness. That is, the film thickness after drying is the product of the wet film thickness and the non-volatile content of the solution, and the desired wet film thickness is determined from this.
The annular body 35 may have a hollow structure. Further, in order to prevent sinking, feet or arms for supporting the annular body 35 may be provided on the outer peripheral surface of the annular body 35 or on the coating tank 33.
[0035]
FIG. 4 shows other coating methods. When the method shown in FIG. 4 is used, the polyimide precursor solution 42 is placed in the annular coating tank 47, and the core body 41 is passed from the lower part to the upper part to perform coating. An annular sealing member 48 made of a flexible plate material such as polyethylene or silicone rubber is provided at the bottom of the annular coating tank 47 so that the solution does not leak. In the drawing, intermediate bodies 49 are attached above and below the core body 41.
The annular coating method using the annular coating tank 47 has the advantage of requiring less solution than the dip coating method shown in FIG. The annular body 45 is installed on the polyimide precursor solution 42 in a freely movable state as described above.
[0036]
The annular body 45 is installed in a freely movable state so that the annular body 45 can move on the polyimide precursor solution 42 with a slight force. And a method of supporting the annular body 45 by air pressure. When the core 41 is raised from the solution through the hole 46 of the annular body 45, frictional resistance is generated between the core 41 and the annular body 45 due to the presence of the solution, and a lifting force acts on the annular body 45, The body 45 is slightly lifted. At this time, the annular body 45 moves so that the frictional resistance with the core body 41 becomes constant in the circumferential direction, and the gap becomes constant, so that the applied film thickness becomes uniform in the circumferential direction.
[0037]
When the polyimide precursor solution is applied on the core body by using an apparatus as shown in FIG. 3 or 4, and then dried, a polyimide precursor film is formed. The drying temperature is preferably 50 to 150 ° C., and the drying time is preferably 30 to 200 minutes. In the case where the polyimide precursor film sags due to the effect of gravity before drying, it is preferable to make the core horizontal and rotate it at about 10 to 60 rpm.
[0038]
At the time after drying, the polyimide precursor film contains about 10 to 40% by mass of the initial content of the solvent, and the polyimide precursor film still has flexibility. Therefore, the polyimide precursor film cannot be removed from the core, and does not maintain the strength as a tubular object.
Here, in order to promote the removal of the solvent, the polyimide precursor coating may be immersed in water before or after drying the polyimide precursor to replace the solvent with water.
[0039]
(Polyimide film forming step)
After forming the polyimide precursor film, a gap is provided between the polyimide precursor film and the core at both ends of the polyimide precursor film, and then a heat treatment is performed to form a polyimide film.
The gap is formed between the core 51 and the polyimide precursor film 50 as shown in the cross-sectional view of FIG.
As a method of forming the gap 51, for example, there is a method of blowing air or inserting a thin film between the core body 51 and the polyimide precursor film 50. Alternatively, an adhesive tape may be wrapped around the end of the core body 51 before application, application may be performed from above, and after drying, the tape may be peeled off to provide a gap.
[0040]
Next, as the heating conditions for performing the condensation reaction of the polyimide precursor, the heating temperature is preferably 350 to 450 ° C., and the heating time is preferably 20 to 60 minutes. At this time, it is preferable to raise the temperature stepwise or gradually at a constant rate, instead of immediately raising the temperature, until the temperature is reached so that the film is unlikely to swell.
[0041]
The polyimide resin shrinks with a strong force when the condensation reaction is caused by heating. At that time, in the production method of the present invention, since a gap is provided between the core body and the polyimide precursor film at the end of the film, the length of the film shrinks at the end because the film can move in the axial direction. In addition, since the central part cannot move in the axial direction, the thickness shrinks in the thickness direction. As a result, a film having a larger thickness at the end than that at the center is formed (see FIG. 1).
[0042]
In addition, when the length of the film shrinks in the axial direction at the end, the shrinkage increases toward the end, so that the shrinkage occurs inward. Thereby, the central portion of the endless belt expands (see FIG. 2).
[0043]
After the above steps, the core is cooled and the polyimide resin film is removed from the core to obtain an endless belt. The endless belt may be further subjected to slit processing, punching hole punching processing, tape winding processing, or the like as necessary.
[0044]
When an endless belt is used as a transfer member, conductive particles are dispersed in a polyimide material. Examples of the conductive particles include carbon-based substances such as carbon black, carbon fiber, and graphite; metals or alloys such as copper, silver, and aluminum; tin oxide, indium oxide, antimony oxide, and SnO. ₂ -In ₂ O ₃ Conductive metal oxides such as composite oxides; conductive whiskers such as potassium titanate; and the like.
[0045]
When an endless belt is used as a fixing member (fixing belt), it is effective to form a non-adhesive resin layer (non-adhesive layer) on the belt surface in order to prevent fusion of toner adhering to the surface. Examples of the material of the (non-adhesive layer) include fluorine resins such as polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkylvinyl ether copolymer (PFA), and tetrafluoroethylene-hexafluoropropylene copolymer (FEP). Is mentioned.
For the non-adhesive layer, carbon powder, inorganic compound powder such as titanium oxide, barium sulfate, etc., for improving abrasion resistance, electrostatic offset, affinity with oil for preventing toner adhesion, etc. Materials other than resin may be included.
When the endless belt is a fixing belt, the thickness of the polyimide resin layer is preferably 50 to 150 μm, and the thickness of the non-adhesive layer is preferably 5 to 50 μm.
[0046]
In order to form a layer made of a fluororesin as the non-adhesive layer, a method of applying the aqueous dispersion to the surface of the endless belt and baking it is preferable. When the adhesion of the fluororesin layer is insufficient, there is a method of forming a primer layer on the endless belt surface as necessary. Examples of the material of the primer layer include polyphenylene sulfide, polyether sulfone, polysulfone, polyamide imide, polyimide and derivatives thereof, and it is preferable that the primer layer further contains at least one compound selected from fluororesins. The thickness of the primer layer is preferably in the range of 0.5 to 10 μm.
[0047]
In order to form a primer layer and a layer made of a fluororesin (non-adhesive layer) on the endless belt, a polyimide resin film may be formed on the surface of the core body by heating, and then these may be applied and formed. Alternatively, a primer layer and a fluororesin dispersion may be applied on the polyimide precursor film, and then heated to simultaneously perform the imidization condensation reaction and the firing treatment of the fluororesin. In that case, even without the primer layer, the adhesion of the fluororesin layer may become strong.
[0048]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.
[0049]
[Example 1]
N-methylpyrrolidone solution of polyimide precursor (trade name: U varnish, manufactured by Ube Industries, Ltd., solid content concentration: 18%, viscosity: 5 Pa · s) and carbon black (trade name: Conductex 975, manufactured by Colombian Carbon Co., Ltd.) Were mixed at a solid content weight ratio of 21% and dispersed by a sand mill for 24 hours. Further, a silicone leveling agent (trade name: DC3PA, manufactured by Toray Silicone Co., Ltd.) was added to a solid content of 200 ppm and mixed well to prepare a coating solution. This was placed in an annular coating tank 47 having an inner diameter of 220 mm and a height of 60 mm in FIG.
[0050]
An aluminum cylinder having an outer diameter of 168 mm and a length of 500 mm was prepared as the core body 41, and the surface thereof was roughened to Ra 1.0 μm by blasting using spherical alumina particles.
(Release layer forming step)
Thereafter, a silicone release agent (trade name: KS700, manufactured by Shin-Etsu Chemical Co., Ltd.) was applied and baked at 300 ° C. for 1 hour (release layer thickness: about 0.01 μm).
[0051]
(Precursor film formation step)
After the stainless steel annular body 45 having an outer diameter of 190 mm, a minimum inner diameter of 169.2 mm, and a height of 30 mm was placed on the solution surface, the axial direction of the core body 41 was made vertical, and the intermediate body 49 was fitted vertically. It passed through the annular coating tank 47 at a speed of 1 m / min. On the way, the annular body 45 did not come into contact with the core 41, and a polyimide precursor coating film having a wet film thickness of about 600 μm was formed on the core 41.
[0052]
After lifting the core 41, the core 41 was placed in a drying oven at 150 ° C. while being rotated at 20 rpm while the axis of the core 41 was horizontal, and dried for 1 hour. As a result, a polyimide precursor film was formed. The polyimide precursor film had no strength as a tubular material and could not be removed from the core 41.
[0053]
(Polyimide film forming step)
In this state, air was blown into both ends of the polyimide precursor film from an air gun while paying attention to breakage, and a gap was formed from both ends to about 30 mm.
[0054]
Thereafter, the polyimide precursor was heated at 200 ° C. for 30 minutes and at 350 ° C. for 30 minutes to imidize the polyimide precursor. By removing the film after cooling to room temperature, a polyimide resin endless belt without swelling could be obtained.
The film thickness was uniform at 70 μm in a portion 300 mm wide from the center, but gradually increased toward the end, 73 μm in a portion 30 mm from each of the ends, both ends and each end. It was 75 μm in the portion from to 20 mm.
[0055]
Further, as shown in FIG. 2, the endless belt was stretched on two rolls 24 having a diameter of 30 mm, and the state of the end portion 22 and the center portion 25 was examined. Was observed. The protrusion height h in FIG. ₃ Was 6 mm.
[0056]
[Comparative Example 1]
In Example 1, after the polyimide precursor coating film was dried to form a polyimide precursor film, a polyimide resin endless belt was prepared in the same manner as in Example 1 except that no gap was formed at the end of the film. Manufactured. The film thickness was uniform at 70 μm from the center to the end. The endless belt was stretched around two rolls 24 having a diameter of 30 mm in the same manner as in Example 1, and the state of the end portion 22 and the center portion 25 was examined. Was not done.
[0057]
Each of the belts of Example 1 and Comparative Example 1 was stretched on two stainless steel rolls each having a diameter of 10 mm, and pulled with a force of 9.8 N. In the endless belt of Example 1, the center portion swelled outward, but with the endless belt of Comparative Example 1, the swelling was not observed.
Next, one of the rolls was rotated at 60 rpm, and the other roll was driven to rotate, and the meandering of the endless belt was examined. The endless belt of Example 1 rotated normally, whereas the endless belt of Comparative Example 1 rotated. Inside, a phenomenon of gradually moving to the left or right was observed.
[0058]
[Example 2]
In Example 1, after the polyimide precursor film was dried and cooled to room temperature, an aqueous dispersion of PFA (trade name: AD-2CR, manufactured by Daikin Industries, Ltd.) was applied by dip coating.
Specifically, the end of the polyimide precursor film is coated and immersed in the paint with the axial direction of the core body vertical, and then pulled up at a speed of 0.4 m / min to remove the PFA coating film. Formed.
[0059]
Subsequently, after drying at room temperature for 5 minutes, drying was performed at 60 ° C. for 10 minutes. Thereafter, the mixture was heated at 380 ° C. for 30 minutes to form a polyimide resin film and sinter the PFA coating film. By removing the belt after cooling to room temperature, an endless belt having a 30 μm thick PFA layer on a 70 μm thick polyimide resin could be obtained. The adhesion between the polyimide resin and the PFA layer was sufficient.
[0060]
This endless belt could be driven without meandering even when used in a transfer fixing device driven to rotate by a roll provided on the inner surface of the belt.
[0061]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a polyimide resin endless belt which is hardly meandered even when driven to rotate and in which wrinkles due to meandering are suppressed, and a method for manufacturing the same.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view for explaining a film thickness of a polyimide resin endless belt of the present invention.
FIG. 2 is a partial cross-sectional perspective view for explaining a state where another endless polyimide resin belt of the present invention is stretched.
FIG. 3 is an explanatory view of a dip coating apparatus using an annular body.
FIG. 4 is an explanatory view of another dip coating apparatus using an annular body.
FIG. 5 is a schematic explanatory view showing a state where a gap is formed between an end portion of a polyimide precursor film and a core.
[Explanation of symbols]
31, 41, 51 ... core
32, 42 ... polyimide precursor solution
33 ... Coating tank
34,44… Coating film
35, 45 ... Annular body
36, 46 ... (annular) holes
47 ... annular coating tank
48… Circular sealing material
49 ... Intermediate
50: polyimide precursor film
51 ... gap
22 ... end
23 ... Central part
24 ... Roll

Claims (4)

A polyimide resin endless belt, wherein a thickness of a central portion in a width direction is smaller than both end portions. The endless polyimide resin belt, wherein the thickness of the both end portions is 1.05 to 1.2 times the thickness of the central portion. A polyimide resin endless belt characterized in that a central portion in the width direction swells outward from an end portion when stretched by two rolls. A method for producing a polyimide resin endless belt according to claim 1, wherein a release layer forming step of forming a release layer by subjecting a surface of the core to a roughening process, and forming a polyimide on the surface of the release layer. A precursor film forming step of applying and drying a precursor solution to form a polyimide precursor film, and providing a gap between the polyimide precursor film and the core at both ends of the polyimide precursor film, followed by heating. A polyimide film forming step of forming a polyimide film by performing a treatment.

Images