JP2007190887A - Method for manufacturing seamless belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a seamless belt which can form a uniform film thickness by a simple means at short times without requiring maintenance, and an apparatus using the same. <P>SOLUTION: The method for manufacturing the seamless belt comprises forming a coating liquid film by applying a precursor solution of a belt such as a thermosetting resin in a proper amount to an inner surface or outer surface with respect to a cylindrical rotating mold and separating from the rotating mold after the coating liquid film is hardened, in which a correction roller 1 is provided in the position parallel to the cylindrical rotating mold, a uniform boundary air layer 2 is generated in the surface of the correction roller by rotating at a high speed of the correction roller, moving the correction roller in this state in parallel, approaching the correction roller up to a predetermined gap to the coating liquid film 3 which is coated with the rotating mold 4 before drying and rotating the rotating mold, so as to make the film thickness of the coating liquid film uniform. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  In the present invention, an appropriate amount of a belt precursor solution (hereinafter referred to as “coating liquid”) such as a thermosetting resin is applied on the inner or outer surface of a cylindrical rotating mold, and the coating liquid film is cured. The present invention relates to a method for producing a seamless belt obtained by releasing from a rotating mold, and more generally, relates to a film formation by resin coating, a film production method, and a disk surface such as an optical disk. It can also be used to form a uniform film on a flat surface such as an FPD.

The following are prior arts related to the invention of this application.
(1) Japanese Patent Application Laid-Open No. 2002-126600 describes an invention of “a coating device on the surface of an endless belt, a coating method using the device and an endless belt”, and the problems and configuration of the present invention are as follows. is there.
The problem of this prior art is to provide a coating device and a coating method for an endless belt from which a coating layer having no joint portion can be obtained.

The configuration of the present invention is such that a powder coating gun, a spreading doctor blade for homogenizing powder, and a far-infrared heater are provided on an endless belt above an endless belt that is wound around a biaxial rotation support device and rotated. Arranged in this order along the direction of travel, a scraper doctor blade, a hot-air blow device, and a mirror drum that equalize the thickness of the molten resin are placed below the endless belt along the direction of travel of the endless belt. It is arranged in order.
This blade method is an expensive method in that an endless belt as a base is used to obtain a uniform film. In addition, since the parts are easily softened in terms of coating with a thermoplastic resin, they cannot be used for built-in parts in which the temperature inside the apparatus is high. The doctor blade for scraping molten resin requires frequent maintenance.

(2) Japanese Patent Application Laid-Open No. 2004-237261 describes an invention of “application method, application device, and endless belt”, and the problems and configurations of the invention are as follows.
For example, a problem is to provide a coating method and a coating apparatus capable of uniformly coating a film thickness even when the film thickness is relatively thick using a coating liquid having a high viscosity, and an endless belt obtained thereby. It is.

In addition, the configuration is a coating method in which the coating liquid is applied to the surface of the core body, and the annular body provided with holes larger than the outer diameter of the core body cross section can be freely moved to the coating liquid filled in the coating tank After being immersed in the coating liquid through the core through the hole of the annular body, the desired height is set so that the annular body is lifted from the coating liquid surface and the bottom surface of the annular body does not leave the coating liquid surface. The core body is relatively raised from the coating liquid.
This dipping method is not only costly, but also difficult to keep the viscosity of the liquid constant because of the large-scale manufacturing facilities, and dripping is severe in applications where the coating liquid contains a low-volatile solvent. This method cannot be used.

(3) Japanese Patent Application Laid-Open No. 2005-134840 describes an invention of “conductive belt and conductive belt manufacturing method”, and the problems and configurations of the present invention are as follows.
The problem is that it is used as an intermediate transfer belt of a color image forming apparatus of a wet development type, and has an appropriate flexibility in the thickness direction on the outer surface, and therefore transfer of a toner image from an electrostatic latent image holding member. And the transferability to the transfer medium are excellent, and the wear or peeling of the surface layer is suppressed and the durability is excellent.

In addition, the configuration is such that the material constituting the base layer is continuously supplied from the nozzle to the outer surface of the rotating mold while rotating the cylindrical rotating mold, and at the same time, the nozzle is moved in the direction of the rotation axis of the rotating mold. Then, the material is uniformly applied.
This spiral coating method is effective for obtaining a substantially uniform film, but when the belt surface after drying is observed, spiral marks can be clearly confirmed visually. Therefore, there is no problem if it is used for a paper conveyance belt or the like, but it cannot be used for an application such as an intermediate transfer belt in which film thickness unevenness easily affects image quality. Also, it takes a long time to apply.

(4) Japanese Patent Laid-Open No. 2000-326349 discloses an invention of “Seamless belt manufacturing method and apparatus”, and the problems and configurations are as follows.
The problem is that a seamless belt can be manufactured easily and inexpensively with relatively simple equipment, and the working environment is improved by not using an organic solvent.

The structure is such that a mandrel (cylindrical body) with a smooth surface is rotated at a constant speed, and a thermoplastic raw material powder is uniformly adhered to the outer peripheral surface thereof by an electrostatic powder coating method. Is heated and melted to form a continuous endless film, which is cooled and solidified, and then peeled off from the mandrel.
In this spray method, it is necessary to mask an area where coating is not desired, which not only increases the material cost but also requires a long time for maintenance. Further, it is often not suitable depending on the viscosity of the coating solution and the contained solvent.

(5) Japanese Patent Application Laid-Open No. 2000-158554 discloses an invention of “Endless Belt Forming Apparatus and Forming Method”, and the problems and configurations are as follows.
An object of the present invention is to provide an endless belt forming apparatus capable of making the film thickness uniform even when the inner surface of the coating mold is shaken when using a centrifugal molding method in which a core mold is inserted into the coating mold and the film is formed. It is to provide a forming method.

The configuration includes a coating mold that forms a film by casting the belt precursor liquid on the inner surface by rotation, and a core mold that is placed on the inner peripheral surface of the coating mold. A rotating body to be driven is provided at both ends thereof, and a releasable leveling member is supported on the same axis between the rotating bodies so as to be free to rotate. And a uniform nip.
The leveling process is preferably performed in a state where the film is dry to the touch (not sticky even when touched with a finger).
This centrifuge method requires correction from the almost dry state to homogenization (correction for homogenization when the membrane is almost dry), and requires a large pressing force on the core mold. The productivity is not good considering the insertion and removal of the core. In addition, the film itself before correction needs to be formed substantially uniformly, and the ability to correct film thickness unevenness is small. Therefore, it takes a long time to correct even the target variation.

[Problems of the prior art]
In image forming apparatuses such as copiers, printers, and facsimile machines, high quality and low cost of the rotating belt are required due to demands for size reduction, weight reduction, cost reduction, and shortening of start-up time.
In the case of this application, if there is a seam in the belt, it is necessary to set up an image forming process at a timing that avoids the seam portion, which not only complicates the mechanism but also disadvantageously reduces the printing speed. Therefore, an endless belt (also referred to as a seamless belt or an endless belt) having no seam portion has been demanded as a rotating belt used in the electrostatic copying process.
Practical examples of the endless belt are frequently used for a fixing belt, an intermediate transfer belt, a paper conveying belt, and the like.

In particular, in the intermediate transfer belt, if the film thickness is partially different, the image quality such as color unevenness, color misregistration, and whiteout is greatly affected. Therefore, the in-plane deviation of film thickness (variation) is less than ± several μm. It is required to fit in.
Conventionally, in manufacturing the endless belt, a belt precursor solution (coating solution) such as a thermosetting resin is poured into the inner peripheral surface of a cylindrical rotating mold, and the centrifugal force due to the high-speed rotation of the rotating mold. A manufacturing method called a centrifugal molding method in which a film is smoothed to an almost uniform film by spreading on the inner peripheral surface and then heat-dried and cured is widely used.

However, with this centrifugal molding method, if the coating solution is highly viscous, it takes a long time to smooth the coating solution to a uniform thickness by centrifugal force, and an appropriate amount of coating solution is required to spread the coating solution. Therefore, it is difficult to form a thin film (unsuitable for forming a multilayer film).
JP 2002-126600 A JP 2004-237261 A JP 2005-134840 A JP 2000-326349 A JP 2000-158554 A

In order to solve the above problems, various methods as described above have been proposed. However, expensive manufacturing facilities are required, it takes a long time to equalize, and frequent maintenance is required. It is not a satisfactory level.
Therefore, an object of the present invention is to provide a method and an apparatus for forming a uniform film thickness by a simple means, in a short period of time, without maintenance.

  As a means for achieving the above object, a method of correcting the coating liquid film by smoothing the surface using a blade is assumed, but according to this method, it is necessary to wipe off the coating liquid adhering to the blade every time, In addition, when creating a seamless belt, when the blade is pulled away from the coating liquid surface, the coating liquid pulls the thread and disturbs the coating liquid film surface, or the blade separation marks remain on the coating liquid film surface. Therefore, it is not practical.

The solution of the present invention is based on the following (a) to (c).
(B) While rotating the correction roller at a high speed, (b) The correction roller is moved in parallel until a predetermined gap is reached with respect to the liquid film before drying applied to the rotation mold, and (c) the rotation mold is rotated. Make it.
According to this solution, the thickness unevenness of the coating liquid film is uniformly corrected without contacting the correction roller.
Therefore, it is possible to form a uniform film thickness in a short time by a simple means without maintenance.

And the reason that the liquid film can be corrected without the need for maintenance and without leaving traces accompanying the pulling of the correction roller is as follows (see FIG. 1). .
(A) When the correction roller 1 is rotated at a high speed, a boundary air layer 2 (= a uniform and fast air flow) is generated on the roller surface (FIG. 1A).
(B) When the correction roller 1 is brought close to the coating liquid film 3 applied almost uniformly on the rotating mold 4, the surface layer of the coating liquid film 3 has a portion showing a fast flow velocity 5 and a portion showing a slow flow velocity 6. (Fig. 1 (b)),
(C) According to Bernoulli's theorem, the air pressure 7 in the part where the flow velocity is fast is lower than the air pressure 7 in the slow part (FIG. 1 (c)),
(D) The coating liquid flows from the high pressure portion to the low pressure portion (reference numeral 8 in FIG. 1D), and the coating liquid film 3 in the portion where the air pressure 7 is low rises (FIG. 1D).
(E) Then, when the correction roller 1 is further brought closer, the liquid film surface rises until just before the surface of the liquid film contacts the correction roller 1 (FIG. 1 (e)),
(F) Since there is a fast air flow (reference numeral 5 in FIG. 1 (e)), the correction roller 1 does not come into contact with the surface of the coating liquid film 3 due to the obstruction of the air layer ( Not wet).

(G) When the correction roller 1 is further brought closer to the coating liquid film 3 (FIG. 1 (f)), the surface of the liquid film is recessed along the surface of the correction roller 1 (FIG. 1 (f)). Also in this case, the correction roller does not contact the coating liquid film.
(H) The distance between the correction roller 1 and the coating liquid film 3 is kept at an appropriate constant level, and the rotary mold 4 is slowly rotated as it is to move the surface of the coating liquid film relative to the correction roller 1 in parallel. By doing so, a correction operation is performed on the entire surface of the coating liquid film, in which the concave portion of the coating liquid film is pulled up and the convex section is pushed down. As a result, a uniform coating liquid film having almost no thickness unevenness is formed (FIG. 1 (g)).
(I) Since the correction roller 1 is not in contact with the coating liquid film 3, no detachment trace accompanying the separation of the correction roller is generated, and cleaning (wiping) of the correction roller 1 is unnecessary. .

(1) Invention of Claim 1 thru | or 3 The thickness of the coating liquid film apply | coated to the internal peripheral surface or the outer peripheral surface of the rotary metal mold | die 4 and 4a by the simple means which only rotates the correction roller 1 at high speed. Since the coating liquid film does not adhere to the correction roller 1 because it is corrected and becomes uniform, there is no need for cleaning work on this, and the surface of the formed coating liquid film may have a leaving mark due to the pulling of the correction roller. Therefore, a uniform film thickness can be formed in a short time, and a highly accurate seamless belt can be manufactured.

(2) Invention of Claim 4 Since the thickness of the coating liquid film can be uniformly formed by simple means, the apparatus itself can be reduced in size, weight, and cost, and further, within the rotary mold Since no leaving marks remain on the surface of the coating liquid film formed on the peripheral surface or the outer peripheral surface, a molded product having excellent appearance quality can be manufactured.

Next, embodiments of the present invention will be described with reference to the drawings.
The configuration of the present invention is to apply an appropriate amount of a belt precursor solution (coating liquid; hereinafter referred to as “coating liquid”) such as a thermosetting resin to the inner or outer surface of a cylindrical rotating mold. About the manufacturing method of the seamless belt that is released from the rotating mold after the coating liquid film is cured, the correction roller is installed in a positional relationship parallel to the cylindrical rotating mold, and the correction roller is rotated at high speed. A uniform boundary air layer is generated on the roller surface, and the correction roller is moved in parallel in this state to approach the coating liquid film before drying applied to the rotating mold until a predetermined gap is reached. The film thickness of the coating liquid film is made uniform by rotating the mold. A specific example of this configuration will be described with reference to the following Example 1 (FIG. 2) and Example 2 (FIG. 3).

  In addition, although thermosetting resin is used in Example 1 and Example 2, it can implement also with a thermoplastic resin, UV curable resin, or solvent volatile curable resin. Similarly, Example 1 and Example 2 are for forming a coating film on a cylindrical rotating mold, but can also be applied to those applied to a flat plate. In this case, the correction roller gradually approaches the flat plate while relatively moving the flat plate and the correction roller in the horizontal plane.

In the first embodiment, a thermosetting resin is poured into a cylindrical rotating mold 4, and the belt is obtained by heating and drying and curing the inner peripheral surface by centrifugal force generated by high-speed rotation of the rotating mold 4. This is an example in which the present invention is applied to a manufacturing method called a centrifugal molding method.
A thermosetting resin having a viscosity of about 700 mPa · s is poured into the inner surface of a stainless steel rotating mold 4 having an inner diameter of 180 mm, an outer diameter of 190 mm, and a length of 300 mm, and the rotating mold 4 is gradually rotated to gradually rotate the entire inner surface of the mold. Then, the thermosetting resin is spread almost uniformly by rotating the rotating mold 4 at a high speed up to about 1000 rpm.

Next, the correction roller 1 set on the same central axis as that of the rotating mold 4 is driven by the AC servo motor 9 and accelerated to 5000 rpm and rotated. The correction roller 1 used here is made of stainless steel having an outer diameter of 30 mm and a length of 280 mm, a surface roughness of Ra = 1.6 μm, and a surface treatment containing 20 to 25 Vol% of fluororesin fine particles. "Kaniflon" has been applied.
The reason why the surface roughness Ra of the correction roller is smoothed to 1.6 μm is to correct the surface of the coating solution smoothly, and the surface treatment “Kaniflon” is applied to the correction roller. This is to make it difficult to paint.

Next, the rotational speed of the rotating mold 4 is reduced to about 300 rpm, the correction roller 1 is translated vertically downward from the center of the rotating mold, and the gap with the coating liquid film 3 is held close to about 500 μm. Thereafter, it is slowly lowered while observing the state of the surface of the coating liquid film 3, and is approached until the gap becomes about 50 μm.
Next, the correction roller 1 is returned to the original position, the rotation is stopped, and the rotating mold 4 is heated with a heater so as to reach 120 ° C. After 30 minutes, the rotation of the rotating mold 4 is stopped.

As a result, a resin belt having a uniform thickness is formed in the rotating mold. And as a result of releasing the resin belt from the rotating mold and measuring its thickness, it was confirmed that the variation was 10 μm or less.
In general, it is difficult to form a thin film by the centrifugal method. However, when the present invention is applied, it can be spread evenly even if the coating liquid film 3 is thin. Therefore, a thin film is formed by laminating two or three layers. It is possible to form a multilayer film.

Example 2 is an example in which the present invention is applied to a manufacturing method called an outer surface coating method in which a thermosetting resin is applied almost uniformly on the outer surface of a cylindrical rotating mold and then heated and dried and cured to obtain a belt. FIG. 3).
A thermosetting resin having a viscosity of about 700 mPa · s is formed on the outer surface of a stainless steel rotating mold 4 a having an inner diameter of 180 mm, an outer diameter of 190 mm, and a length of 300 mm, with a uniform thickness in the axial direction via the die coater 10. At the same time, the rotating mold 4a is rotated at a constant speed of 1 rpm, and when the mold 4a is rotated once, the extrusion of the thermosetting resin is stopped. As a result, a substantially uniform cylindrical coating liquid film 3 is formed on the outer surface of the rotating mold 4a.

Next, the correction roller 1 set on the outer side in parallel with the rotating mold 4a is driven by the AC servo motor 9 and accelerated to 5000 rpm and rotated. The correction roller 1 used here is the same as that in the first embodiment.
Next, with the rotational speed of the rotating mold 4 kept at 1 rpm, the correction roller 1 is moved in parallel toward the rotating mold 4 and the gap with the coating liquid film 3 is held close to about 500 μm. Thereafter, the surface is slowly approached while observing the surface of the coating liquid film 3 until the gap reaches about 50 μm.

Next, the correction roller is returned to the original position to stop the rotation, and then the heater is heated so that the rotating mold 4 becomes 120 ° C. After 30 minutes, the rotation of the rotating mold 4 is stopped.
By doing as described above, a resin belt having a uniform thickness is formed outside the rotating mold 4. As a result of releasing the belt from the rotating mold 4 and measuring the thickness, it was confirmed that the thickness variation was 10 μm or less.

[Others]
In Example 1 and Example 2 described above, the rotation speed of the correction roller 1 is set to 5000 rpm, but the rotation speed is not necessarily limited thereto. The appropriate rotation speed depends on the outer diameter of the correction roller. However, when the outer diameter of the correction roller 1 is 30 mm, the boundary air layer is hardly generated when the rotation speed is 1000 rpm or less. There is a problem that the liquid film adheres to the surface of the roller frequently, and if it is 3000 rpm or more, the correcting ability is exhibited, and the above problem does not occur. On the other hand, the higher the speed, the stronger the boundary air layer is generated, but it is preferable, however, when trying to achieve a speed higher than 10000 rpm, motors and bearings become special specifications, and “simple means” cannot be implemented. become.

  The outer diameter of the correction roller is appropriately 20 to 40 mm in consideration of molding accuracy, shape stability at high speed rotation, simplicity of the apparatus, and the like. And if an outer diameter is this range, the rotational peripheral speed 8-16m / sec is an appropriate range.

From the above, the rotation speed of the correction roller is within a suitable range of 5000 to 10,000 rpm when the outer diameter is 20 to 40 mm.
Moreover, although Example 1 and Example 2 set the surface roughness of a correction roller to Ra = 0.02-20 micrometers, it is not necessarily restricted to this.
However, when Ra> 20 μm, there is a problem that a liquid film adheres to the roller surface. On the other hand, the surface roughness Ra is preferably as small as possible so that the coating liquid is less likely to adhere to the correction roller, but there is no significant difference in the effect below 0.01, while Ra <0.02 μm. If it is going to be realized, the creation of the correction roller becomes a special specification, and the present invention cannot be realized "by simple means".
From the above, regarding the surface roughness Ra of the correction roller, the range of “0.02 to 20 μm” is realistic and preferable.

  In addition, the correction effect of the liquid film is not actually determined only by the rotational speed and surface roughness, but the temperature, outer diameter and surface treatment of the correction roller, the viscosity and temperature and surface tension of the coating liquid, and the environmental temperature. In addition, the humidity, mold moving speed, etc. have a complex influence. In consideration of these circumstances and the surface shape accuracy required of the belt, the rotation speed and surface roughness of the correction roller may be appropriately selected.

These are the figures explaining the principle which corrects thickness nonuniformity, without a correction roller touching a liquid film. These are explanatory drawings of Example 1 which formed the coating liquid film | membrane on the inner surface of a rotary metal mold | die, and obtained the seamless belt. These are explanatory drawings of Example 2 which formed the coating liquid film | membrane on the outer surface of a rotary metal mold | die, and obtained the seamless belt.

Explanation of symbols

1: Correction roller 2: Boundary air layer by roller rotation 3: Coating liquid film 4, 4a: Rotating mold 5: High flow rate 6: Slow flow rate 7: Air pressure applied to coating liquid film 8: Flowing coating liquid 9: AC Servo motor (motor for correction roller)
10: Die coater

Claims (4)

An appropriate amount of a precursor solution of a belt such as a thermosetting resin is applied to the inner or outer surface of a cylindrical rotating mold to form a coating liquid film, and after the coating liquid film is cured, the rotating mold is used. In the manufacturing method of the seamless belt to be released,
A correction roller is installed in a positional relationship parallel to the cylindrical rotating mold, and the correction roller is rotated at high speed to generate a uniform boundary air layer on the correction roller surface. Seamless, characterized in that the film thickness of the coating liquid film is made uniform by approaching the coating liquid film before drying applied to the rotary mold until a predetermined gap is reached and further rotating the rotary mold. A method for manufacturing a belt.   In Claim 1, The rotation speed of the said correction roller was 3000-10000rpm, The manufacturing method of the seamless belt of Claim 1 characterized by the above-mentioned.   2. The method for producing a seamless belt according to claim 1, wherein the surface roughness of the correction roller is Ra = 0.02 to 20 [mu] m. Manufacture of a seamless belt that can be applied to a cylindrical rotating mold by applying an appropriate amount of a belt precursor solution such as thermosetting resin to the inner or outer surface of the cylindrical rotating mold and curing the coating liquid film before releasing the mold from the rotating mold. In the device
A correction roller is installed in or outside the cylindrical rotary mold in a positional relationship parallel to the rotary mold, and the correction roller is moved in the direction of approaching and separating from the inner or outer peripheral surface of the rotary mold. Supported as possible,
The coating liquid film is formed by extending the molten resin on the inner peripheral surface or the outer peripheral surface by the rotation of the rotating mold,
By rotating the correction roller at a high speed, a uniform boundary air layer is generated on the correction roller surface, and the predetermined correction gap is applied to the coating liquid film before drying applied to the rotating mold by translating the correction roller in that state. An apparatus for producing a seamless belt, wherein the coating liquid film is made uniform by rotating the rotating mold until the thickness of the coating liquid is further reduced.

Images