JP2005004056A - Method of manufacturing endless belt, and cylindrical core bar - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an endless belt by which the shrinkage of a coating film formed on the outer circumferential surface of a cylindrical core bar in the core axis direction can be suppressed and also the occurrence of uneven film thickness can be reduced. <P>SOLUTION: In the method of manufacturing the endless belt including a polymide resin layer through at least a release agent layer forming process of forming a release agent layer at least on the outer central peripheral surface of the cylindrical core bar, a coating film forming process of forming the coating film by applying at least polymide precursor solution on the outer circumferential surface of the center part and each end part of the cylindrical core bar after the release agent layer forming process, a film forming process of forming a film by drying, heating and baking the coating film, and a peeling/drawing process of drawing the film out of the cylindrical core bar, when the outer central circumferential surface of the cylindrical core bar is defined as a reference plane, at least a part of the outer circumferential surface is positioned on the outer and/or inner circumferential side of the e plane at both end parts of the cylindrical core bar. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing an endless belt used for a photoreceptor, a charging member, a transfer belt, a fixing belt, and the like in an image forming apparatus such as an electrophotographic copying machine and a laser printer, and a cylindrical core used for producing the endless belt. About the body.
[0002]
[Prior art]
In the above applications, a rotating body made of metal, plastic, or rubber is used. However, in order to reduce the size or increase the performance of the apparatus, the rotating body may be preferably deformable, and for this A thin resin belt is used. In this case, if the belt has a seam, a defect due to the seam occurs in the output image. Therefore, it is preferable that there is no seam, and an endless belt is used. The material is preferably a polyimide resin in terms of strength, dimensional stability, heat resistance, etc. (hereinafter, polyimide may be abbreviated as “PI”).
[0003]
Several fixing devices using an endless belt are known (see, for example, Patent Documents 1 and 2).
For a transfer device using an endless belt, for example, a transfer belt made of a PI resin in which conductive powder is dispersed and made semiconductive is stretched around a plurality of rolls and rotated to transfer a toner image to a photoreceptor. (For example, see Patent Document 3). Examples of the conductive powder include carbon black, graphite, and tin oxide.
[0004]
For a transfer fixing device using an endless belt, for example, an endless belt made of semiconductive PI resin is stretched around a plurality of rolls and rotated to transfer a toner image from the photoreceptor onto the endless belt, followed by heating. Thus, there is an apparatus that melts and fixes a toner image on a sheet (see, for example, Patent Document 4).
[0005]
The PI resin endless belt can be produced by, for example, applying a PI precursor solution to the inner surface of a cylindrical body and drying it while rotating (see Patent Document 5), or PI precursor solution on the inner surface of the cylindrical body. However, in these inner surface film forming methods, it is necessary to dry the solvent of the PI precursor solution from the inside of the cylindrical body, so that it takes time to dry. was there.
[0006]
Other endless belt manufacturing methods include, for example, a method in which a PI precursor solution is applied to the surface of a core body by a dip coating method, dried, heated, and then the PI resin film is peeled off from the core body (patent) Reference 7). In this method, since the solvent is dried from the outer surface of the core, the drying time can be shortened, and the shape of the outer surface of the core is molded on the inner surface of the endless belt.
[0007]
Here, as the solvent for the PI precursor solution, an aprotic polar solvent is used, and all of the aprotic polar solvents have a high boiling point and very slow drying. In addition, since the PI resin film has low gas permeability, a part of the film tends to remain even if the solvent is dried.
[0008]
In the method of peeling after forming the PI resin film on the surface of the core body, in the heating process of the film, residual solvent and water generated at the stage where the imidization reaction proceeds are caused between the inside of the film and between the core body and the film. If it stays in the film, it expands by heat and becomes a high-pressure gas, and the PI resin film may swell and deform. This is particularly noticeable when the film thickness is thicker than 50 μm.
[0009]
On the other hand, since the PI resin has a large shrinkage force during the heating reaction, the coating containing the PI resin formed on the outer peripheral surface of the core body shrinks when the endless belt is formed. Such shrinkage is considered to occur non-uniformly and causes uneven film thickness of the endless belt. Further, the semiconductive endless belt in which the conductive powder is dispersed further causes uneven resistance.
When the belt is used, the unevenness of the film thickness is less likely to cause a problem when the degree is light. However, when the unevenness of resistance is used as the transfer belt, the density of the toner to be transferred becomes uneven, which is a serious problem.
For this reason, when manufacturing a conventional endless belt, it is required to minimize resistance unevenness particularly in a semiconductive endless belt in which conductive powder is dispersed, and there is no severe unevenness in film thickness. There has been a demand for reliably obtaining an endless belt.
[0010]
[Patent Document 1]
Japanese Patent Laid-Open No. 5-150679
[Patent Document 2]
JP-A-8-262903
[Patent Document 3]
Japanese Patent Laid-Open No. 10-218850
[Patent Document 4]
Japanese Patent Laid-Open No. 10-20538
[Patent Document 5]
JP-A-57-74131
[Patent Document 6]
Japanese Patent Laid-Open No. 62-19437
[Patent Document 7]
Japanese Patent Laid-Open No. 61-273919
[0011]
[Problems to be solved by the invention]
An object of the present invention is to solve the above problems. That is, when producing an endless belt, the present invention can suppress the occurrence of unevenness in the film thickness of the endless belt by suppressing the contraction of the coating formed on the outer peripheral surface of the cylindrical core in the core axis direction. It is an object of the present invention to provide a belt manufacturing method and a cylindrical core.
[0012]
[Means for Solving the Problems]
In order to achieve the above-mentioned problems, the present inventors have examined in more detail the shrinkage of the film containing the PI resin formed on the outer peripheral surface of the core body when forming the endless belt as described below.
In general, since PI resin has a large shrinkage force during heating reaction, the shrinkage of the coating containing PI resin formed on the outer peripheral surface of the core not only contracts in the film thickness direction but also contracts in the axial direction of the core body. I think that.
[0013]
When the present inventors diligently studied such a shrinkage phenomenon, the amount of shrinkage is not uniform in each part of the coating formed on the outer peripheral surface of the core, and the coating near the center of the core is near the end. It was confirmed that the film thickness was thinner than that of the coating film, particularly when the release agent layer was previously formed on the core surface.
Such film thickness unevenness is relatively easy to move in the axial direction at the end of the core, so the axial length tends to shrink, and the thickness of the core is small. It is considered that the contraction hardly occurs only in the thickness direction because the movement in the axial direction is limited in the central portion.
[0014]
In addition, when the non-uniform shrinkage of the coating as described above occurs, when producing a semiconductive endless belt in which the conductive powder is dispersed, in the portion where the axial shrinkage is large, the conductive powders It is presumed that the contact ratio becomes relatively large, the resistance is likely to be low, and the resistance is high in a portion where the axial contraction is relatively small, resulting in uneven resistance.
Therefore, based on the knowledge as described above, the present inventors considered that it is necessary to be able to fix the coating at both ends of the core body in order to suppress the coating in the axial direction of the core body. I arrived. That is, the present invention
[0015]
<1> A release agent layer forming step of forming a release agent layer on the outer peripheral surface of at least the central portion of the cylindrical core, and a central portion and both ends of the cylindrical core after the release agent layer forming step A coating film forming step of forming a coating film by applying at least a polyimide precursor solution to the outer peripheral surface of the part, a coating film forming step of forming a film by drying and baking the coating film, and the coating film In an endless belt manufacturing method for producing an endless belt including a polyimide resin layer through at least a separation / extraction step that is separated from an outer peripheral surface and is extracted from the cylindrical core body,
When the outer peripheral surface of the central part of the cylindrical core is used as a reference surface, at both ends of the cylindrical core, at least a part of the outer peripheral surface is on the outer peripheral side and / or inner peripheral side of the reference surface. It is an endless belt manufacturing method characterized by being located.
[0016]
<2> The endless belt manufacturing method according to <1>, wherein the cylindrical core is a cylindrical core.
[0017]
<3> The method for producing an endless belt according to <2>, wherein an outer diameter of at least one end portion of the cylindrical core body is smaller than an outer diameter of a central portion of the cylindrical core body. is there.
[0018]
<4> Endless as described in any one of <1> to <3>, wherein a concave portion is provided in at least a part of the outer peripheral surface of at least one end of the cylindrical core. It is a belt manufacturing method.
[0019]
<5> As described in any one of <1> to <4>, a convex portion is provided on at least a part of the outer peripheral surface of at least one end of the cylindrical core. This is an endless belt manufacturing method.
[0020]
<6> A release agent layer forming step of forming a release agent layer on the outer peripheral surface of at least the central portion of the cylindrical core, and the central portion and both ends of the cylindrical core after the release agent layer forming step A coating film forming step of forming a coating film by applying at least a polyimide precursor solution to the outer peripheral surface of the part, a coating film forming step of forming a film by drying and baking the coating film, and the coating film In an endless belt manufacturing method for producing an endless belt including a polyimide resin layer through at least a separation / extraction step that is separated from an outer peripheral surface and is extracted from the cylindrical core body,
In the endless belt manufacturing method, the surface roughness Ra of at least a part of the outer peripheral surface is 0.5 μm or more at both ends of the cylindrical core.
[0021]
<7> The cylinder after the release agent layer forming step is performed by forming a release agent layer on the outer peripheral surface of the central portion and both end portions of the cylindrical core, and after the release agent layer forming step. <6> The endless belt manufacturing method according to <6>, wherein at least a part of the outer peripheral surface of at least both ends of the core is irradiated with ultraviolet rays, and then the coating film forming step is performed.
[0022]
<8> In the cylindrical core used when producing an endless belt at least through the step of forming a coating film on the outer peripheral surface of the central part and both ends of the cylindrical core,
When the outer peripheral surface of the central part of the cylindrical core is used as a reference surface, at both ends of the cylindrical core, at least a part of the outer peripheral surface is on the outer peripheral side and / or inner peripheral side of the reference surface. It is a cylindrical core characterized by being located.
[0023]
<9> The cylindrical core according to <8>, which is cylindrical.
[0024]
<10> The cylindrical core according to <9>, wherein the outer diameter of at least one end is smaller than the outer diameter of the central part of the cylindrical core.
[0025]
<11> The cylindrical core body according to any one of <8> to <10>, wherein a recess is provided in at least a part of the outer peripheral surface of at least one end.
[0026]
<12> The cylindrical core according to any one of <8> to <11>, wherein a convex portion is provided on at least a part of the outer peripheral surface of at least one end. .
[0027]
<13> The cylindrical core body according to any one of <8> to <12>, which is used in the endless belt manufacturing method according to any one of <1> to <5>.
[0028]
<14> In the cylindrical core used when producing an endless belt at least through the step of forming a coating film on the outer peripheral surface of the central part and both ends of the cylindrical core,
At the both ends of the cylindrical core, the cylindrical core is characterized in that the surface roughness Ra of at least a part of the outer peripheral surface is 0.5 μm or more.
[0029]
<15> The cylindrical core according to <14>, which is used in the endless belt manufacturing method according to <6>.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
The endless belt manufacturing method and the cylindrical core of the present invention will be described below by roughly dividing the matters common to the first invention, the second invention, and the first and second inventions.
[0031]
(First invention)
The first aspect of the present invention is a mold release agent layer forming step for forming a release agent layer on the outer peripheral surface of at least the central portion of the cylindrical core, and the cylindrical core after the mold release agent layer forming step. A coating film forming step of forming a coating film by applying at least a polyimide precursor solution to the outer peripheral surface of the central portion and both ends, and a film forming step of forming a coating film by drying and baking the coating film; In the endless belt manufacturing method for producing an endless belt including a polyimide resin layer through at least a peeling / extracting step of peeling the film from the outer peripheral surface and extracting it from the cylindrical core, a central portion of the cylindrical core When the outer peripheral surface is used as a reference surface, at both ends of the cylindrical core body, at least a part of the outer peripheral surface is located on the outer peripheral side and / or the inner peripheral side with respect to the reference surface.
[0032]
Therefore, according to the first aspect of the present invention, since both ends of the cylindrical core body (hereinafter may be abbreviated as “core body”) have a function of fixing the film, they are formed on the outer peripheral surface of the cylindrical core body. The contraction of the coated film in the axial direction of the core can be suppressed, and as a result, the film thickness unevenness of the endless belt can be suppressed.
Further, when the endless belt is a semiconductive belt, uneven resistance can be suppressed, and when the endless belt is used as a transfer belt, the toner density transferred to the transfer belt can be made uniform. .
[0033]
In the present invention, at any point after the coating is formed on the outer peripheral surface of the core body, both ends of the coating are cut away to obtain an endless belt having a desired width. Usually, cutting of both ends of the film can be performed at any stage before or after the peeling / sampling process. Which one to select depends on the method of removing the film (for example, using a hand or by inserting a jig at the interface between the film and the core), or without cutting both ends of the film. It is determined in consideration of whether or not it is easy to pull out the core from the core.
[0034]
Further, in the present invention, the “end portion” of the core body means an end portion in the axial direction of the core body in a broad sense, but in a narrow sense, when both ends of the film are cut to produce an endless belt. This means the part (corresponding to the discarding margin) covered with the film (at both ends) that is finally cut off and discarded, and the “central part” of the core is the final part when making the endless belt It means the part covered with the film used as an endless belt.
[0035]
The release agent layer only needs to be formed on the outer peripheral surface of at least the central portion of the core body, but in order to facilitate the peeling of the coating film at the end portion, the release agent layer is formed on either one end portion or both end portions. Preferably it is.
[0036]
When the cylindrical core used in the first aspect of the present invention uses the outer peripheral surface of the central part of the cylindrical core as a reference surface, at least a part of the outer peripheral surface at the both ends of the cylindrical core is the above-mentioned The shape is not particularly limited as long as it is located on the outer peripheral side and / or the inner peripheral side with respect to the reference plane.
[0037]
The specific shapes of the end portions of the cylindrical core body used in the first invention as described above include the following three types.
That is, (1) in the case where the core body is cylindrical, when the outer diameter of the core body end portion is smaller than the outer diameter of the central portion, (2) a recess is formed in at least a part of the outer peripheral surface of the core body end portion. Are provided. (3) When a convex part is provided on at least a part of the outer peripheral surface of the end part of the core body, the above are three.
[0038]
Here, as for the core used for the 1st present invention, each of both ends should just satisfy any of the above (1)-(3). In this case, the shape of both ends may be the same or different. The shape of the end may be a combination of two or more of (1) to (3).
[0039]
Next, the specific examples of the shapes described in the above (1) to (3) will be described more specifically with reference to the drawings in the case where the shape of the core is cylindrical. The shape of the core is not limited to this.
[0040]
First, (1) when the core is cylindrical, the case where the outer diameter of the end of the core is smaller than the outer diameter of the center will be described.
In this case, for example, a core as shown in FIG. 1 can be mentioned as an example. FIG. 1 is a schematic side view showing an example of a cylindrical core used in the first invention. In FIG. 1, 100 is a cylindrical core body, 101 is a core body central part, 102 is a core body end part, 103 is an outer peripheral surface (reference surface) of the core body central part 101, and 104 is an outer peripheral surface of the core body end part 102. , 105 represent straight lines located on the same plane as the outer peripheral surface (reference surface) 103.
[0041]
In the core body 100, the outer peripheral surface 104 of the end portion 102 is located on the inner peripheral side with respect to the outer peripheral surface (reference surface) 103 of the central portion 101, and the end portion 102 has a smaller outer diameter than the central portion 101. It has a so-called tapered shape in which the outer diameter continuously decreases as it goes in the direction of the part. The outer diameter may be reduced discontinuously as it goes in the end direction.
The specific dimensional shape of the core body 100 shown in FIG. 1 is not particularly limited. However, in order to achieve both the securing of the film fixing function and the ease of peeling / extraction in a balanced manner, the axial length of the end portion 102 is small. The axial length of the core body 100 is preferably in the range of 5 to 20%, and the minimum outer diameter of the end portion 102 is preferably in the range of about 90 to 95% of the outer diameter of the central portion 101. .
[0042]
Next, (2) the case where the recessed part is provided in at least one part of the outer peripheral surface of a core body edge part is demonstrated.
In this case, for example, a core as shown in FIG. 2 can be cited as an example. FIG. 2 is a schematic side view showing another example of the cylindrical core used in the first present invention. In FIG. 2, reference numeral 200 denotes a cylindrical core, 201 denotes a central part of the core, 202 denotes an end of the core, and 203 denotes a groove (concave).
[0043]
The core body 200 has basically the same outer diameter in any part with respect to the axial direction, but the end portion 202 is provided with one groove 203 continuous in the circumferential direction. In addition to the example shown in FIG. 2, for example, a plurality of grooves may be provided in the circumferential direction, or may be provided intermittently in the circumferential direction.
[0044]
The cross-sectional shape of the groove 203 is not particularly limited. In order to prevent the coating film formed on the outer peripheral surface of the core body from breaking when contracted by heating, a gentle V-shaped (V groove angle is 1 degree to 20 degrees). It is preferably within a range of about a degree.
The specific dimensions and shape of the groove 203 are not particularly limited, but the width of the groove 203 is set in the axial direction of the core body 200 in order to achieve both the securing of the film fixing function and the ease of peeling and extraction in a balanced manner. The length is preferably in the range of 0.5 to 5% of the length or in the range of 4 to 15% of the outer diameter of the core body 200, and the depth of the groove 203 is 0.5 to 5% of the outer diameter of the core body 200. It is preferable to be within the range of 5%.
[0045]
Next, (3) the case where a convex part is provided in at least one part of the outer peripheral surface of a core body edge part is demonstrated.
In this case, for example, a core as shown in FIG. 3 can be given as an example. FIG. 3 is a schematic side view showing another example of the cylindrical core used in the first invention. In FIG. 3, reference numeral 300 denotes a cylindrical core, 301 denotes a central part of the core, 302 denotes an end of the core, and 303 denotes a protrusion (convex part).
[0046]
The core body 300 basically has the same outer diameter in any part with respect to the axial direction, but the end portion 302 is provided with protrusions 303 in a line at equal intervals in the circumferential direction. In addition to the example shown in FIG. 2, the protrusions may be provided in a plurality of rows in the circumferential direction, for example, or may have a shape in which the protrusions are continuously connected in the circumferential direction.
[0047]
In addition, the contraction force at the time of the heating reaction of the whole coating film becomes large, so that the axial direction length of the core body 300 and the circumferential direction length are large. For this reason, it is preferable to increase the number of protrusions 303 provided on the end portion 302 as the axial length and the circumferential length of the core body 300 increase. The shapes and sizes of the protrusions 303 provided on the end 302 may be different from each other, but are preferably the same, and the top of the protrusion 303 is not pointed and rounded to prevent the coating film from being broken. It is preferable that the shape is tinged.
[0048]
Further, the height of the protrusion 303 is not particularly limited, but if it is too high, the coating film is broken, and if it is too low, the film cannot be sufficiently fixed, and the axial shrinkage increases. May end up. For this reason, it is preferable that the height of the protrusion 303 be in the range of 20 to 50% of the coating thickness before drying.
[0049]
The cylindrical core used in the first aspect of the present invention is extremely suitable for producing an endless belt including at least a polyimide layer using a polyimide precursor solution as described above.
However, the cylindrical core used in the first aspect of the present invention is not limited to this, and the endless belt undergoes at least a process of forming a coating film on the outer peripheral surface of the central portion and both ends of the cylindrical core. If the manufacturing method of the endless belt manufactured by is used, it can be used even if it does not include a polyimide layer as a layer constituting the endless belt. However, the cylindrical core used in the first aspect of the present invention is particularly suitable when contraction of the coating film formed on the outer peripheral surface of the core occurs in the manufacturing process of the endless belt.
[0050]
(Second invention)
As described above, the first aspect of the present invention uses the difference in the three-dimensional shape in the core axis direction to fix the coating to the shape portion having the hooking function of the end portion. However, the present inventors also examined a method that does not depend on the difference in the three-dimensional shape in the core axis direction, and devised the second invention described below.
[0051]
That is, the second aspect of the present invention includes a release agent layer forming step of forming a release agent layer on at least the outer peripheral surface of the cylindrical core, and the cylindrical core after the release agent layer forming step. A coating film forming step for forming a coating film by applying at least a polyimide precursor solution to the outer peripheral surface of the center and both ends of the body, and a film forming process for forming a coating film by drying and heating and firing the coating film And an endless belt manufacturing method for producing an endless belt including a polyimide resin layer through at least a separation / extraction step of separating the film from the outer peripheral surface and extracting the film from the cylindrical core. At both ends, the surface roughness Ra of at least a part of the outer peripheral surface is 0.5 μm or more.
[0052]
Therefore, according to the second aspect of the present invention, since both ends of the cylindrical core body have a function of fixing the film, the contraction of the film formed on the outer peripheral surface of the cylindrical core body in the axial direction of the core body is suppressed. The same effects as those of the first aspect of the present invention can be obtained, such as suppressing unevenness of the film thickness of the endless belt.
[0053]
The second aspect of the present invention is to fix the coating to the end by increasing the frictional force between the outer peripheral surface and the coating by imparting roughness to the outer peripheral surface of the core end. The surface roughness Ra of at least a part of the outer peripheral surface at both ends of the body is preferably as large as possible. Specifically, it is preferably 0.7 μm or more, and more preferably 1.0 μm or more. The upper limit of the surface roughness Ra is not particularly limited, but is practically 2.0 μm or less.
Moreover, it is preferable that the area | region where surface roughness Ra of a core body edge part outer peripheral surface is 0.5 micrometer or more is provided over the whole core body edge part outer peripheral surface.
[0054]
In the present invention, the surface roughness Ra indicates an arithmetic average roughness specified by JIS. In the present invention, a stylus type surface roughness measuring machine (for example, Surfcom 1400A, manufactured by Tokyo Seimitsu Co., Ltd.) Means the value measured under the following conditions. That is, the measurement conditions were determined based on JIS B0601-1994, with an evaluation length Ln = 4 mm, a reference length L = 0.8 mm, and a cutoff value = 0.8 mm.
[0055]
Of course, it is possible to produce an endless belt by combining the first and second aspects of the present invention described above with reference to specific examples.
[0056]
The cylindrical core used in the second aspect of the present invention is extremely suitable for the production of an endless belt including at least a polyimide layer using a polyimide precursor solution as described above.
However, the cylindrical core used in the second aspect of the present invention is not limited to this. The cylindrical core used in the second aspect of the present invention is an endless belt manufacturing method in which an endless belt is manufactured through at least a step of forming a coating film on the outer peripheral surface of the central part and both ends of the cylindrical core. Even if the polyimide layer is not included as a layer constituting the endless belt, it can be used.
[0057]
However, the cylindrical core used in the second aspect of the present invention is particularly suitable when contraction of the coating film formed on the outer peripheral surface of the core occurs in the manufacturing process of the endless belt. Further, it is of course possible to use a cylindrical core body that combines the first and second aspects of the invention when manufacturing an endless belt that does not include such a polyimide layer.
[0058]
(Common matters of the first and second present inventions)
Next, other matters common to the first and second inventions described above will be described.
-Core-
The shape of the cylindrical core used in the present invention is not particularly limited as long as it is cylindrical. For example, the cylindrical core may have a polygonal cross-sectional shape, but is practically cylindrical. Is preferred.
In addition, in the core, in order to efficiently escape the gas generated when the coating film is heated to the outside of the coating film, and to prevent the occurrence of bulge defects of the film due to the gas, at least the outer peripheral surface of the core body central portion It is preferable that the surface is roughened. Of course, the outer peripheral surface of the end portion of the core body can be similarly roughened, and when the endless belt is produced according to the second invention, the roughness of the central portion and the end portion are different from each other. You can also
In addition, when a coating film does not generate | occur | produce a gas at the time of a heating, it is not necessary to give such a roughening process for the purpose of degassing.
[0059]
Roughening methods include known methods such as powder blasting and honing, metal blades, metal files, metal brushes, sandpaper, etc. Is available. At the time of processing, while rotating the core body, the processing member is moved in the axial direction of the core body while being pressed against the outer peripheral surface of the core body. The processing method / condition is selected as necessary according to the core outer diameter, desired roughness, or roughened shape.
[0060]
In addition, it is preferable that the provision of roughness to the outer peripheral surface of the core body for the purpose of degassing is in the range of 0.5 to 3.0 μm in terms of surface roughness Ra. When Ra is smaller than 0.5 μm, the PI resin film may be swollen when the PI resin film is formed. On the other hand, when Ra is larger than 3.0 μm, bubbles may be generated in the coating film when the PI precursor solution is applied to the core or when the coating film is dried.
When the coating film shrinks during heating due to the roughening of the core surface, a deviation occurs between the coating film and the irregularities on the outer peripheral surface of the core body, and a slight gap is formed between the PI resin film and the outer peripheral surface of the core body. And the residual solvent or water can be effectively released.
[0061]
The material of the core is not particularly limited, but metals such as aluminum, zinc, copper, stainless steel and nickel are preferable. When the material of the core is aluminum, zinc, or copper, it may be plated with chromium or nickel so that the outer peripheral surface is not easily damaged.
[0062]
-Production of endless belt-
In the present invention, an endless belt is produced through a cylindrical core body through at least four steps of a release agent layer forming step, a coating film forming step, a film forming step, and a peeling / extracting step. You may have another process.
The endless belt produced using the present invention is an endless belt including at least a polyimide resin layer, may be composed of a polyimide layer alone, or composed of two or more layers including a polyimide layer. May be. In the latter case, the endless belt is manufactured such that a film that becomes a polyimide layer is always formed on the outer peripheral surface of the core.
In the following description, the individual steps will be described on the assumption that the endless belt is a single polyimide layer. Of course, in the case of two or more layers, the individual steps described below may be changed, It can be easily manufactured by reviewing the combination.
[0063]
-Releasing agent layer forming step-
In the present invention, in order to ensure the peelability between the PI resin film formed in contact with the outer peripheral surface of the core body and the outer peripheral surface of the core body, at least the central portion, preferably the central portion and both end portions of the outer peripheral surface of the core body. Is previously provided with a release agent layer.
For forming the release agent layer, a known fluororesin or silicone resin can be used as the release agent. For example, a release agent made of silicone oil or the like is applied to the outer peripheral surface of the core body, and the release layer is formed. Form. As the release agent, a baking type silicone release agent (for example, KS-700 (manufactured by Shin-Etsu Chemical Co., Ltd.)) is most preferable.
[0064]
-Coating film formation process (PI precursor coating process)-
After the release agent layer forming step, a coating film is formed by applying at least a polyimide precursor solution to the outer peripheral surface of the central portion and both end portions of the cylindrical core after the release agent layer forming step. A film forming step is performed.
If the endless belt is composed only of the polyimide layer, only the PI precursor coating step described later may be performed. However, if the endless belt is an endless belt of two or more layers including the polyimide layer, the PI precursor coating is performed. After the step, a coating film of a layer formed on the outer peripheral side of the polyimide layer is formed as necessary. The PI precursor coating process will be described in detail below.
[0065]
In the PI precursor application step, a coating film is formed by applying a solution containing the PI precursor (PI precursor solution) to the outer peripheral surface of the core body. Conventionally known PI precursors can be used.
The solvent used for dissolving the PI precursor is a conventionally known aprotic polar solvent such as N-methylpyrrolidone, N, N-dimethylacetamide, acetamide, N, N-dimethylformamide or the like. The concentration, viscosity, etc. of the solution are appropriately selected.
[0066]
As a method of forming a coating film by applying the PI precursor solution to the outer peripheral surface of the core body, a dip coating method in which the core body is dipped in the PI precursor solution and pulled up, or on the surface while rotating the core body in the horizontal direction. A flow coating method in which a solution is discharged, a blade coating method in which a coating film is metalized with a blade, and an existing known method can be employed. In the above-mentioned flow coating method and blade coating method, the coating part is formed in a spiral shape by horizontally moving the coating part in the axial direction of the core, but the PI precursor solution solvent is slow to dry at room temperature. In addition, the spiral seam is naturally smoothed.
[0067]
The PI precursor solution has a very high viscosity, and the amount of adhesion in the dip coating method is too large. Therefore, as disclosed in JP-A-2002-91027, the PI precursor solution has a circular shape larger than the outer diameter of the core. It is preferable to adopt a method in which an annular body provided with holes is installed on the PI precursor solution in a freely movable state, and the core body is relatively raised from the solution through the holes of the annular body.
[0068]
The coating film forming method will be described with reference to the drawings. FIG. 4 is a schematic cross-sectional view showing an example of a coating film forming method used in the present invention, and once the core body immersed in the PI precursor solution is raised, the coating film surface is coated on the surface of the core body. This shows a state in which is formed. FIG. 4 shows only the main part related to the dip coating using the annular body, and the peripheral part of the dip / pull-up device is omitted. In FIG. 4, 1 is a core, 2 is a PI precursor solution, 3 is a coating tank, 4 is a coating (PI precursor coating), 5 is an annular body, and 6 is a hole in the annular body. To express.
[0069]
In the present invention, “apply on the core” means to apply on the surface of the core and, if the surface has a layer, on the layer. Further, “raising the core” means a relative rise with respect to the liquid level of the PI precursor solution, and includes the case of “stopping the core and lowering the liquid level of the PI precursor solution”.
In the dip coating method using the annular body shown in FIG. 4, the annular body 5 is floated on the liquid surface of the PI precursor solution 2 in the coating tank 3 so that it can freely move. Next, the core body 1 is immersed in the PI precursor solution 2 through the hole 6 of the annular body, and then lifted in the direction of the arrow U, whereby the coating film 4 is formed on the surface of the core body 1. Moreover, the film thickness of the coating film 4 is adjusted according to the difference between the outer diameter of the core body 1 and the hole diameter of the hole 6 of the annular body.
[0070]
The annular body 5 is made of various metals, plastics and the like that are not eroded by the solvent used for the PI precursor solution, and may have a hollow structure for weight reduction. Further, in order to prevent the annular body 5 from sinking into the PI precursor solution 2, legs and arms that support the annular body 5 may be provided on the outer peripheral surface of the annular body and / or the coating tank.
[0071]
A value obtained by dividing the difference between the outer diameter of the core body 1 and the minimum hole diameter of the hole 6 of the annular body by 2 (hereinafter abbreviated as “gap width”) is a thickness immediately after application of the desired coating film 4 (hereinafter referred to as “gap width”). , Abbreviated as “wet film thickness”). The film thickness of the coating film 4 after drying (hereinafter abbreviated as “dry film thickness”) is represented by the product of the wet film thickness and the non-volatile content concentration of the PI precursor solution 2. Desired.
However, the gap width is not always reflected directly as the wet film thickness due to the viscosity and / or surface tension of the PI precursor solution 2 to be used. For this reason, according to the PI precursor solution 2 to be used, it is preferable to set the gap width within a range of 1 to 2 times the desired wet film thickness.
[0072]
The shape of the hole 6 of the annular body 5 is not particularly limited as long as the lower part is wide with respect to the liquid surface of the PI precursor solution 2 and the upper part is narrow, as shown in FIG. In addition to a shape that gradually narrows linearly, a shape that gradually narrows in a stepped or curved shape may be used.
[0073]
Next, another example of another coating film forming method will be described. FIG. 5 is a schematic cross-sectional view showing another example of the coating film forming method used in the present invention, and by raising the core from the center of the PI precursor solution placed in the dip coating tank, It shows a state in which a coating film is formed on the body surface. In FIG. 5, reference numerals 1, 2, 4, 5 and 6 are substantially the same as those shown in FIG. 1, 7 is an annular coating tank, 8 is an annular sealing material, 9 and 9 ′ represents an intermediate.
The annular coating method shown in FIG. 5 has the advantage that the required amount of the PI precursor solution 2 is smaller than that of the dip coating method shown in FIG.
[0074]
In the annular coating method using the annular body shown in FIG. 5, a hole through which the core body 1 passes is provided at the bottom of the annular coating tank 7, so that the PI precursor solution does not leak from this hole. An annular sealing material 8 made of a flexible plate material such as silicone rubber or fluorine resin is attached. Further, the core body 1 arranged so that the axial direction is the vertical direction, the upper end face is fixed to the intermediate body 9, and the lower end face is fixed by the intermediate body 9 ', and the lifting device (not shown) It is moved in the vertical direction via intermediates 9 and 9 'installed in
[0075]
Further, the annular body 5 is floated on the liquid surface of the PI precursor solution 2. However, also in FIG. 5, when the core body is pulled up, the annular body 5 may be completely floated freely on the liquid surface of the PI precursor solution 2 as shown in FIG. 4. Further, the outer peripheral surface of the annular body 5 may be supported by a roll or a bearing, or may be supported by applying air pressure through a pressing body, but the annular body 5 is formed so that a coating film 4 having a uniform film thickness can be formed. It is preferable to support the body 5 so that it can move freely with respect to the liquid surface vertical and horizontal directions.
When the core body 1 is raised from the PI precursor solution 2 in the direction of the arrow U ′ through the annular body 6 through the intermediate body 9, the core body 1 and the annular body 5 are interposed by the PI precursor solution 2. A frictional resistance is generated between them, an ascending force acts on the annular body 5, and the annular body 5 is slightly lifted in the direction of the arrow U ′.
[0076]
When the annular body 5 is slightly lifted in this way, the annular body 5 moves in the horizontal direction so that the frictional resistance with the core body 1 is constant in the circumferential direction, and the gap width becomes constant. When the gap width between the annular body 5 and the core body 1 is changed, the frictional resistance is increased in the portion which is to be narrowed, and the gap width is widened on the opposite side to cause an unbalanced state in which the frictional resistance is reduced. Since the annular body 5 moves in the horizontal direction so that the portion where the resistance is large is reduced, that is, the gap width is widened, the annular body 5 is not in contact with the core body 1 and a constant gap width is always maintained. It is.
[0077]
When the core body 1 is raised, even if the core body 1 is slightly inclined or the raising means of the core body 1 has a flare, the annular body 5 can move in the horizontal direction following the core body. There is also an advantage that the wet film thickness is kept constant.
[0078]
In order for the annular body 5 to function as described above, the annular body 5 must be lifted to some extent from the liquid surface, and is preferably lifted by 2 mm or more from the stop state position. The height lifted from the liquid level increases as the rising speed of the core body 1 increases. However, when the annular body 5 is lifted and the lower end surface thereof is separated from the liquid surface, the annular body 5 is brought to the liquid level when the lowermost portion of the core body 1 has finished passing through the hole 6 of the annular body. Will fall. In this case, bubbles are entrained in the PI precursor solution 2, which is very inconvenient when the coating operation is repeated.
[0079]
For the above reasons, when the core body 1 is raised, the lifting height of the annular body 5 with respect to the liquid surface is not too high and not too low, and needs to be kept within a certain range. For that purpose, it is preferable to adjust the rising speed of the core body 1 by detecting the height of the annular body 5 from the liquid surface. That is, when the annular body 5 is lifted high and tries to move away from the liquid surface, the rising speed is slowed. Conversely, when the lifting height of the annular body is small, the rising speed is fastened. The height of the annular body from the liquid level can be detected using various mechanical and optical detection devices. For convenience, the height of the annular body 5 from the liquid level is visually determined. You can also adjust the speed manually.
[0080]
-Film formation process-
The film forming process includes a drying process for drying the PI precursor coating film and a heating process for heating and baking.
The PI precursor coating film formed on the outer peripheral surface of the core is preferably dried at a drying temperature of 50 to 150 ° C. and a drying time of 30 to 200 minutes. When dripping occurs in the PI precursor coating film due to the influence of gravity before drying, it is preferable to rotate the core in the axial direction at about 10 to 60 rpm.
[0081]
At the time after drying, the PI precursor coating film contains about 10 to 40% of the initial content of the solvent, and the coating film still has flexibility. Therefore, the coating film cannot be removed from the core and does not retain the strength as a tubular object. In order to accelerate the removal of the solvent, the PI precursor coating film may be immersed in water before or after the PI precursor coating film is dried to replace the solvent and water.
[0082]
Next, the heating conditions for forming the PI precursor film by heating and firing the PI precursor coating film to form a PI precursor film are preferably performed at a temperature of 350 to 450 ° C. for 20 to 60 minutes. At this time, it is preferable to raise the temperature stepwise or gradually at a constant rate, rather than immediately increasing the temperature until the temperature is reached so that the film is unlikely to swell.
[0083]
The PI resin contracts with a strong force when it undergoes a condensation reaction by heating. In the present invention, at both ends of the outer peripheral surface of the core body, as described above, a mechanism for preventing the shrinkage of the PI precursor film is provided. Therefore, a PI resin film having a uniform film thickness can be formed in the core axis direction.
[0084]
-Peeling and sampling processes-
After cooling the core body, remove the film from the core body as described above and then cut off both ends of the film, or cut both ends of the film on the core body and then remove the film from the core body. Thus, an endless belt can be obtained. The endless belt may be further subjected to slit processing, punching drilling processing, tape winding processing, or the like as required.
[0085]
-Layer structure and application of endless belt-
When using an endless belt produced by utilizing the present invention as a transfer body, conductive particles are dispersed in the PI material. Examples of the conductive particles include carbon-based materials 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 Examples thereof include conductive metal oxides such as complex oxides and conductive whiskers such as potassium titanate.
[0086]
When an endless belt is used as a fixing member, it is effective to form a non-adhesive resin layer on the belt surface (outer peripheral surface) in order to prevent adhesion of toner adhering to the surface (outer peripheral surface).
Examples of the material constituting the resin layer include fluorine resins such as polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), and tetrafluoroethylene-hexafluoropropylene copolymer (FEP). Is mentioned. For non-adhesive layers, carbon powder, inorganic compound powders such as titanium oxide and barium sulfate, etc. are used to improve wear resistance, electrostatic offset, and compatibility with toner adhesion prevention oil. Materials other than resin may be included.
The PI resin layer preferable as the fixing belt has a thickness of 25 to 200 μm, and the non-adhesive layer has a thickness of 5 to 50 μm.
[0087]
In order to form the fluororesin layer on the outer peripheral surface of the endless belt, a method in which the aqueous dispersion is applied to the belt surface and baked is preferable. Moreover, when the adhesiveness of a fluororesin layer is insufficient, there is a method of forming a primer layer on the endless belt surface as necessary. Examples of the material constituting the primer layer include polyphenylene sulfide, polyethersulfone, polysulfone, polyamideimide, polyimide, and derivatives thereof, and it is preferable that at least one compound selected from fluororesins is included. The thickness of the primer layer is preferably in the range of 0.5 to 10 μm.
[0088]
In order to form the primer layer and the fluororesin layer on the outer peripheral surface of the endless belt, the material for forming these layers may be applied and formed on the PI resin film (after the heat treatment) formed on the outer peripheral surface of the core body. it can. Alternatively, a dispersion liquid containing a material constituting the primer layer or a material constituting the fluororesin layer is applied onto the PI precursor coating film (before the heat treatment) formed on the outer peripheral surface of the core body, and then heated. The imidization condensation reaction and the fluorocarbon resin firing treatment may be performed simultaneously. In the latter case, the adhesion between the PI resin layer and the fluororesin layer may be sufficiently strong even without the primer layer. In this case, it is not necessary to form the primer layer.
[0089]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.
[0090]
(Comparative Example 1)
N-methylpyrrolidone solution containing PI precursor (trade name: U varnish, Ube Industries, Ltd., solid concentration 18 wt%, viscosity 5 Pa · s), carbon black (trade name: Conductex 975, Colombian Carbon Co., Ltd.) Manufactured at a solids weight ratio of 21% and dispersed by a sand mill for 24 hours. Furthermore, a silicone leveling agent (trade name: DC3PA) was added and mixed well so as to be 200 ppm based on the solid content to obtain a coating solution. This was put in the annular coating tank 7 shown in FIG.
[0091]
Next, an aluminum cylinder having an outer diameter of 68 mm and a length of 500 mm is prepared as a core, and the entire outer peripheral surface thereof is roughened to a surface roughness Ra of 1.0 μm by blasting using spherical alumina particles. After the surface formation, a silicone release agent (trade name: KS700, manufactured by Shin-Etsu Chemical Co., Ltd.) was further applied, and a baking treatment was performed at 300 ° C. for 1 hour to form a release agent layer.
[0092]
On the other hand, after the stainless steel annular body 5 having an outer diameter of 84.0 mm, a minimum inner diameter of 68.9 mm, and a height of 25 mm is placed on the solution surface filled in the annular coating layer 7, the intermediate body 9 is fitted to both ends. A coating film was formed on both ends and the center of the core that was passed through the annular coating tank 7 at a speed of 1 m / min with the axial direction of the core being vertical. When the coating film was formed, the annular body 5 did not contact the outer peripheral surface of the core body, and a PI precursor coating film having a wet film thickness of about 450 μm was formed on the core body.
[0093]
After pulling up the core body, the axial direction of the core body was leveled, placed in a drying furnace at 120 ° C., and the coating film was dried for 1 hour while rotating at 18 rpm. Thereafter, the coating film was heated at 340 ° C. for 30 minutes to form a polyimide resin film. Since the film after heating was peeled off from the core, the film was directly removed by hand. Finally, both ends 40 mm of the film were cut with a uniform width to obtain an endless belt of Comparative Example 1 having a width of 311 mm.
The shrinkage ratio in the axial direction of the core when the coating is dried and heated is as large as around 2.8%, and the width direction of the endless belt obtained by cutting both ends (in the axial direction of the core) Equivalent) was 80 μm at the center and 84 μm at both ends.
[0094]
(Example 1)
Instead of the core body used in Comparative Example 1, both ends 30 mm of the core body used in Comparative Example 1 are tapered at an inclination angle of 5 °, and at both ends as shown in FIG. A core body whose outer diameter gradually decreased was used.
An endless belt of Example 1 having a width of 318.7 mm was produced in the same manner as in Comparative Example 1 except that such a core was used.
In addition, when the coating film is dried and heated to form a coating film, the shrinkage ratio in the axial direction of the core is about 0.4%, and the width direction of the endless belt obtained by cutting both ends (corresponding to the axial direction of the core body) ) Was as uniform as 80 μm from the center to both ends.
[0095]
(Example 2)
Instead of the core body used in Comparative Example 1, the core body used in Comparative Example 1 has a width of 3 mm and a depth of 2 mm on the outer peripheral surface of 20 mm in the axial direction from the end portion of the core body as shown in FIG. A core body having one groove at each end of the core body was used.
An endless belt of Example 2 having a width of 318.6 mm was produced in the same manner as in Comparative Example 1 except that such a core was used.
The shrinkage ratio in the axial direction of the core when the coating is dried and heated to 0.4% is the width direction of the endless belt obtained by cutting both ends (corresponding to the axial direction of the core) The film thickness was as uniform as 80 μm from the center to both ends.
[0096]
Example 3
Instead of the core used in Comparative Example 1, a core as shown in FIG. 3 was used. Specifically, in the core used in Comparative Example 1, eight holes with a diameter of 1 mm on the outer peripheral surface of 20 mm in the axial direction from the end portion of the core are equidistantly spaced in the circumferential direction (total of both ends is 16). This core was used, and a core body in which a stainless steel pin having the same diameter was inserted 0.3 mm above the outer peripheral surface was used.
A film was formed on the outer peripheral surface of the core in the same manner as in Comparative Example 1 except that such a core was used. Thereafter, both ends of the coating were cut at a uniform width, and then the coating on the center of the core was extracted from the core to produce an endless belt of Example 3 having a width of 318.1 mm.
In addition, when the coating film is dried and heated to form a coating film, the shrinkage ratio in the axial direction of the core body is 0.6%, and the width direction of the endless belt obtained by cutting both ends (corresponding to the axial direction of the core body) The film thickness was substantially uniform at 80 μm at the center and 82 μm at both ends.
[0097]
【The invention's effect】
As described above, according to the present invention, when an endless belt is produced, the film thickness unevenness of the endless belt is reduced by suppressing contraction of the coating formed on the outer peripheral surface of the cylindrical core in the core axis direction. It is possible to provide an endless belt manufacturing method and a cylindrical core that can suppress the occurrence of the above.
[Brief description of the drawings]
FIG. 1 is a schematic side view showing an example of a cylindrical core used in the first invention.
FIG. 2 is a schematic side view showing another example of a cylindrical core used in the first invention.
FIG. 3 is a schematic side view showing another example of a cylindrical core used in the first present invention.
FIG. 4 is a schematic cross-sectional view showing an example of a coating film forming method used in the present invention.
FIG. 5 is a schematic cross-sectional view showing another example of a coating film forming method used in the present invention.
[Explanation of symbols]
1 core
2 PI precursor solution
3 Application tank
4 Coating (PI precursor coating)
5 Rings
6 Holes in the ring
7 Annular coating tank
8 annular sealing material
9 Intermediate
100 cylindrical core
101 center of core
102 Core end
103 Outer peripheral surface (reference surface) of core central portion 101
104 Outer peripheral surface of core end portion 102
105 Straight line located on the same surface as the outer peripheral surface (reference surface) 103
200 Cylindrical core
201 center of core
202 core end
203 groove (concave)
300 Cylindrical core
301 center of core
302 Core end
303 Protrusion (convex part)

Claims (13)

A release agent layer forming step for forming a release agent layer on the outer peripheral surface of at least the central portion of the cylindrical core, and the outer periphery of the central portion and both ends of the cylindrical core after the release agent layer forming step A coating film forming step for forming a coating film by applying at least a polyimide precursor solution to the surface, a film forming step for forming a film by drying and baking the coating film, and the coating film from the outer peripheral surface. In an endless belt manufacturing method for producing an endless belt including a polyimide resin layer through at least a peeling / extraction step that is peeled off and extracted from the cylindrical core body,
When the outer peripheral surface of the central part of the cylindrical core is used as a reference surface, at both ends of the cylindrical core, at least a part of the outer peripheral surface is on the outer peripheral side and / or inner peripheral side of the reference surface. An endless belt manufacturing method, wherein the endless belt is positioned. The endless belt manufacturing method according to claim 1, wherein the cylindrical core is a cylindrical core. The method for manufacturing an endless belt according to claim 2, wherein an outer diameter of at least one end of the cylindrical core is smaller than an outer diameter of a central portion of the cylindrical core. The endless belt manufacturing method according to any one of claims 1 to 3, wherein a concave portion is provided in at least a part of an outer peripheral surface of at least one end of the cylindrical core. The endless belt manufacturing method according to any one of claims 1 to 4, wherein a convex portion is provided on at least a part of the outer peripheral surface of at least one end of the cylindrical core. A release agent layer forming step for forming a release agent layer on the outer peripheral surface of at least the central portion of the cylindrical core, and the outer periphery of the central portion and both ends of the cylindrical core after the release agent layer forming step A coating film forming step for forming a coating film by applying at least a polyimide precursor solution to the surface, a film forming step for forming a film by drying and baking the coating film, and the coating film from the outer peripheral surface. In an endless belt manufacturing method for producing an endless belt including a polyimide resin layer through at least a peeling / extraction step that is peeled off and extracted from the cylindrical core body,
A method for producing an endless belt, wherein at both ends of the cylindrical core, the surface roughness Ra of at least a part of the outer peripheral surface is 0.5 μm or more. The cylindrical core after the release agent layer forming step is performed by forming a release agent layer on the outer peripheral surface of the central portion and both ends of the cylindrical core, and after the release agent layer forming step The method for producing an endless belt according to claim 6, wherein at least a part of the outer peripheral surface of at least both ends is irradiated with ultraviolet rays, and then the coating film forming step is performed. In the cylindrical core used when producing an endless belt at least through the step of forming a coating film on the outer peripheral surface of the central part and both ends of the cylindrical core,
When the outer peripheral surface of the central part of the cylindrical core is used as a reference surface, at both ends of the cylindrical core, at least a part of the outer peripheral surface is on the outer peripheral side and / or inner peripheral side of the reference surface. A cylindrical core body characterized by being positioned. The cylindrical core body according to claim 8, wherein the cylindrical core body is cylindrical. The cylindrical core according to claim 9, wherein the outer diameter of at least one end is smaller than the outer diameter of the central part of the cylindrical core. The cylindrical core according to any one of claims 8 to 10, wherein a concave portion is provided in at least a part of the outer peripheral surface of at least one end. The cylindrical core according to any one of claims 8 to 11, wherein a convex portion is provided on at least a part of the outer peripheral surface of at least one end portion. In the cylindrical core used when producing an endless belt at least through the step of forming a coating film on the outer peripheral surface of the central part and both ends of the cylindrical core,
The cylindrical core body characterized in that at both ends of the cylindrical core body, the surface roughness Ra of at least a part of the outer peripheral surface is 0.5 μm or more.

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