JP3378244B1 - Manufacturing method and manufacturing apparatus for seamless belt - Google Patents

Abstract

A seamless belt having excellent dimensional accuracy, easy solvent recovery, and excellent productivity by a centrifugal casting method is provided. SOLUTION: In a seamless belt made of a cylindrical resin film obtained by baking after forming a film by a centrifugal casting method, the cylindrical resin film has a shrinkage rate of 1 during baking after forming a film.
5% or less, a step of injecting a resin solution into a rotating cylindrical mold, a step of forming a resin film on an inner wall of the cylindrical mold by centrifugal force, and peeling from the inner wall of the cylindrical mold. Inserting an inner cylinder having a diameter smaller than the film diameter into the formed cylindrical resin film and firing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seamless belt manufacturing method and manufacturing apparatus.

[0002]

2. Description of the Related Art A seamless belt made of a cylindrical resin film is often used in fixing devices such as printers and copying machines. A seamless belt is made by injecting a resin solution in which a heat-resistant resin is dissolved in a solvent whose main component is an aprotic polar solvent such as N-methyl-2-pyrrolidone or dimethylacetamide into a cylinder, and rotating the cylinder while heating it. After being subjected to centrifugal molding, it is obtained by firing. The aprotic polar solvent generated in the process of centrifugal molding is recovered. In order to obtain a uniform film thickness by the centrifugal molding method, a lid is provided at both ends of the rotary mold, and an air flow direction control plate is installed inside the lid to change the air flow in the mold, thereby achieving a uniform film thickness. A method for producing a seamless belt (Japanese Patent Laid-Open No. 2000-153530), a method for producing a seamless belt in which air as a gas is blown into a rotating cylinder by a blowing fan to control the belt thickness (Japanese Patent Laid-Open No. 2001-2001). 135
No. 3 gazette), centrifugal molding provided with a receiving roll which can be rotationally driven in a furnace, a cylinder as a mold placed on the receiving roll, and a heater for heating the inside of the cylinder and a blower for exhausting air in the furnace. Machines (Japanese Patent Laid-Open No. 6-39858) are known.

[0003]

However, the aprotic polar solvent used as a solvent has a problem that it has a strong property of dissolving an organic substance. Therefore, conventionally, in order to recover the solvent, the entire manufacturing apparatus is closed system, or the both ends of the rotary mold are provided with lids and the inside of the mold is heated under reduced pressure to recover the solvent from the lid portion. Although the method (Japanese Patent Laid-Open No. 2000-153530, etc.) is performed, there are problems that the apparatus becomes complicated, solvent recovery cannot be performed efficiently, and productivity is poor.

There is also a problem that it is difficult to make the thickness of the cylindrical resin film uniform. In particular, when a polyimide-based resin is used as the heat-resistant resin, the polyimide film passes through the polyamic acid film to change the shrinkage rate during firing after film formation, or it is difficult to obtain a resin film having a uniform thickness. Blistering may occur in the process of forming a polyimide film. Therefore, there is a problem that the yield is low and the productivity is reduced.

The present invention has been made in order to solve such a problem and is excellent in dimensional accuracy such as variation in shrinkage rate and film thickness, easy solvent recovery, and improved productivity by the centrifugal casting method. An object of the present invention is to provide an excellent seamless belt manufacturing method and manufacturing apparatus.

[0006]

The seamless belt manufacturing method according to the present invention has a shrinkage ratio of 15% or less at the time of baking after film formation in the cylindrical axial direction and the circumferential direction, and a film thickness variation of ±
5μm or less, a method for producing a seamless belt composed of a mixed resin cylindrical film of an aromatic polyimide resin and an aromatic polybenzimidazole resin, wherein the aromatic polyimide resin and the aromatic polyimide resin in a rotating cylindrical mold. A step of injecting a polybenzimidazole resin forming solution, a step of forming a resin film on the inner wall of the cylindrical mold by centrifugal force, and a step of forming a resin film on the cylindrical resin film peeled from the inner wall having a diameter smaller than the film diameter And a step of inserting a cylinder and firing at a firing temperature of 300 to 350 ° C. In the present invention, the contraction rate after firing after film formation means the length of the cylindrical resin film that has contracted after firing, when the reference length in the axial direction or the circumferential direction of the cylindrical resin film before firing is 100. Represent

Further, in the above manufacturing method, the outer peripheral surface of the inner cylinder is roughened to have a roughness Ra of 5 to 10 μm. In addition, the outer diameter of the inner cylinder is 3 to 10 mm larger than the diameter of the resin film formed by the rotary centrifugation method.
It is characterized by a small diameter.

A seamless belt manufacturing apparatus according to the present invention comprises a rotating cylindrical mold, and an open lid fixed to both ends of the cylindrical mold, or a V ring that slides directly on both ends of the cylindrical mold. Two fixed cylinders, and at least one of the fixed cylinders has a diameter reduced from the diameter of the fixed cylinder at the position where the V ring is disposed, and a blower provided on one of the fixed cylinders and a blower. A resin film forming means including a heat source provided between the V ring, an inner cylinder having a diameter smaller than the diameter of the formed cylindrical resin film, and the cylindrical resin film. And a resin film forming means having a means for inserting and firing the cylinder.

When a cylindrical resin film is formed and fired by the centrifugal casting method, it shrinks in the axial direction of the cylinder and in the circumferential direction. Therefore, when the cylindrical resin film is manufactured, the axial direction is reduced by the amount of shrinkage. It is necessary to lengthen the length, which easily causes manufacturing loss. However, by setting the shrinkage ratio during firing after film formation in the cylinder axis direction and the circumferential direction to 15% or less, a uniform film thickness can be obtained.
In addition, a seamless belt with reduced production loss and increased yield was obtained. Further, a seamless belt having a uniform film thickness with a film thickness variation of about ± 6% was obtained irrespective of the end portions, the central portion and the like of the cylindrical resin film. By using the seamless belt manufacturing method and manufacturing apparatus as the manufacturing method and manufacturing apparatus according to the present invention, the shrinkage ratio can be easily adjusted.
% Or less of the seamless belt was obtained. The present invention is based on such knowledge.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A seamless belt according to the present invention will be described with reference to FIG. FIG. 1 is a perspective view of a seamless belt. The seamless belt 1 is composed of a resin film obtained by film formation and baking by a centrifugal casting method. The shrinkage rate of this cylindrical resin film after film formation and firing is 15% or less. The shrinkage rate is calculated as a shrinkage rate (%) by collecting a test piece before firing and measuring the length after firing under the same conditions as when firing after forming a resin film. The test piece for measuring the shrinkage in the axial direction of the cylinder can be measured by collecting the portion A in FIG. 1, and the test piece for measuring the shrinkage in the circumferential direction can be collected in the portion B. Shrinkage rate is 15%
The method to be described below is a method of inserting a cylinder having a diameter slightly smaller than the diameter of the cylindrical resin film before firing into the inner diameter of the cylindrical resin film, fixing both axial end portions and firing.
Examples include a method in which the cylindrical surface is roughened to suppress shrinkage and movement of the cylindrical resin film and then baked.

As the resin forming the resin film, a resin soluble in a solvent can be used. For example, polyethylene terephthalate resin, polybutylene terephthalate resin, polyethylene naphthalate resin, polyarylate resin, polyester elastomer resin, polycarbonate resin, polyphenylene ether resin, AS resin, ABS resin, aromatic polyimide resin, aromatic polyamide resin, aromatic polyamideimide Resins, aromatic polybenzimidazole resins and the like, and combinations thereof may be mentioned. Among these, when used in a fixing device, etc., an aromatic polyimide resin having excellent heat resistance, an aromatic polyamide resin, an aromatic polyamideimide resin, an aromatic polybenzimidazole resin, etc. and an aromatic system of a combination thereof. A resin is preferable, and an aromatic polybenzimidazole resin or a combination of an aromatic polybenzimidazole resin and an aromatic polyimide resin is particularly preferable because it has excellent high temperature durability. The main solvent used for the aromatic resin is N, N-
Aprotic polar solvents such as dimethylformamide, N, N-dimethylacetamide and N-methyl-2-pyrrolidone are preferred. These aprotic polar solvents are about 200
It has a boiling point of around ℃, it is difficult to completely volatilize the solvent in the process of forming the resin film by the centrifugal casting method, and a minute amount of the solvent remains in the resin film. In particular, in the case of the above aromatic resin, a part of the solvent is likely to form a complex with the resin in which the solvent is dissolved, so that a trace amount of the solvent is likely to remain in the resin film. By baking, these solvents can be volatilized.

An apparatus for manufacturing the seamless belt 1 will be described with reference to FIG. FIG. 2 is a cross-sectional view of a film forming apparatus centering on a cylindrical mold portion used in the process of forming a resin film by a centrifugal casting method. The film forming apparatus has a cylindrical mold 2 that rotates around a cylindrical axis. Cylindrical mold 2
For example, a cylindrical mold made of carbon steel and having an inner diameter of φ148 mm, a thickness of 6 mm, and a length of 350 mm and which is plated with hard chrome can be used. The inner peripheral surface of the cylindrical mold 2 is mirror-finished.

A pair of open lids 3, 3 are attached to both ends 2a and 2b of this cylindrical mold to rotate coaxially with the cylindrical mold 2. The open lid 3 has a cylindrical shape with an L-shaped cross section, and the inner diameter surface of the cylinder is fixed to the cylindrical mold 2 via an O-ring 4. Further, two fixed cylinders 6 provided with the V-ring 5 are arranged on the thrust side of the open lid 3 with the tip of the V-ring 5 slidingly in contact therewith. The V-ring 5 is shielded from the outside by slidingly contacting the thrust side of the cylindrical mold 2 when the cylindrical mold 2 rotates, and prevents the solvent generated from the resin solution from evaporating to the outside.
At this time, the V ring 5 may be brought into direct sliding contact with the end of the cylindrical mold 2.

Air blowing means 7 and a heat source 8 are provided on one side of the fixed cylinder 6, and air heated from one of the fixed cylinders 6 through the inside of the cylindrical mold 2 to the other fixed cylinder 6. Will be sent. In the present invention, the blowing means 7 includes various blowing fans, and the heat source 8 includes various heaters. Although illustration is omitted, the air blower 7 and the heat source 8 may be provided with an air flow direction control unit such as an air flow direction control plate, an air flow amount control unit, or an external heating unit of the cylindrical mold 2.

As shown in FIG. 3, it is preferable that at least one of the fixed cylinders 6 is reduced in diameter toward the side where the V ring 5 is attached. The diameter reduction is preferably gradually reduced so as not to disturb the flow of wind. By reducing the diameter, the solvent generated from the resin solution can be easily cooled, and the solvent can be easily recovered. For example, the solvent can be recovered by dissolving the solvent in water by blowing exhaust gas through a condenser to recover the solvent.

Since the cylindrical mold 2 rotates independently of the fixed cylinder 6, various rotating means can be adopted as long as it can rotate the cylindrical mold 2. As the rotation means,
An apparatus for supporting the bottom of the outer peripheral surface of the cylindrical mold 2 by two rollers arranged coaxially with the cylindrical mold, and rotating the cylindrical mold 2 by driving and rotating the rollers, the outer periphery of the cylindrical mold 2. Examples include a device in which bearings are provided at both ends of the surface, the inner ring of the bearing is fixed to the outer peripheral surface and a rotary drive device is provided, and a device in which the outer periphery of the cylindrical mold 2 is driven by a belt.

A method of manufacturing a seamless belt using the above apparatus will be described. An aromatic polyamic acid varnish, an aromatic polybenzimidazole varnish, or a mixed varnish of these which can be converted into an aromatic polyimide resin is poured into a cylindrical mold. Concentration of varnish injected,
The viscosity and amount can be determined by the diameter, length, thickness, etc. of the seamless belt. For example, the concentration of varnish is 3% to 20%
The viscosity and the viscosity are preferably about 0.5 to 5 Pa · s.

The injected varnish is uniformly applied to the inner wall of the cylindrical mold by the centrifugal force generated by the rotation of the cylindrical mold.
The varnish is injected from the fixed cylinder 6 side into the cylindrical mold using a nozzle or the like. Further, the resin film is formed on the inner wall of the cylindrical mold by the flow of heated air simultaneously with the coating. Optimum film forming conditions are set according to the size of the rotating cylinder, the thickness of the seamless belt, and the characteristics of the resin solution such as the type and viscosity of the solvent. For example, when using a rotating cylinder with an inner diameter of 110 mm and a length of 360 mm, the number of rotations is 1000 to 75
00 rpm, air flow rate is 0.1-1 liter / min, air temperature is
70-120 degreeC is preferable.

The formed cylindrical resin film is inserted into an inner cylinder having a diameter smaller than this film diameter and baked, so that in the case of a polyimide resin, complete formation of an imide ring and complete removal of a solvent can be achieved. For other resins, complete solvent removal. The inner cylinder used in this step is preferably made of the same material as the cylindrical mold and has a roughened surface. The outer diameter of the inner cylinder is preferably 3 to 10 mm smaller than the diameter of the resin film formed by the rotary centrifugation method. If it is less than 3 mm, it is difficult to insert it into the cylindrical resin film, and if it exceeds 10 mm, the shrinkage rate becomes too large. The roughened shape of the surface is a shape that suppresses shrinkage of the cylindrical resin film in the cylinder axis direction during firing. Specifically, the surface roughness (Ra) defined by JIS B0601 is preferably about 5 μm. For the above-mentioned aromatic polyimide resin or aromatic polybenzimidazole resin, the firing conditions are a firing temperature of 300 to 350 ° C.
The firing time is preferably 0 to 90 minutes.

The seamless belt obtained by the above method is
The dimensional accuracy is excellent, and the shrinkage rate during firing after film formation can be 15% or less. Therefore, it can be suitably used for a fixing device such as a printer or a copying machine.

[0021]

Example 1 Aromatic polyimide varnish (manufactured by Ube Industries, Ltd., solid content concentration as polyamic acid: 18% by weight) Solution 17.8 g
And an aromatic polybenzimidazole varnish (manufactured by Clariant Japan KK, solid content concentration: 10% by weight) solution 8.
After mixing with O g, the mixture was diluted with 14.2 g of dimethylacetamide to obtain a mixed resin solution. The viscosity of the obtained mixed resin solution is 3 Pa · s, and the weight ratio of the aromatic polyimide resin and the aromatic polybenzimidazole resin is 8: 2. The resulting solution was applied to a cylindrical mold (inner diameter φ110 mm × outer diameter φ13
0 mm x length 360 mm), and rotated at a rotation speed of 2500 rpm, an air flow rate of 0.7 l / min, and an air temperature of 80 ° C to obtain a film. Insert this film into a roughened inner cylinder (outer diameter φ100 mm × 360 mm, Ra 10 μm), and
It was placed in an oven at 50 ° C., left for 60 minutes and then taken out to obtain a seamless belt made of a mixed resin film and having a thickness of 40 μm. The shrinkage factor of this seamless belt in the axial direction is 8
%, And the shrinkage ratio in the circumferential direction was 12%. The film thickness of this seamless belt was in the range of 40 ± 5 μm when measured at four points in the circumferential direction at both ends and in the central part, and was a uniform film thickness.

Example 2 35.0 g of a solution of aromatic polybenzimidazole varnish (manufactured by Clariant Japan KK, solid content concentration: 10% by weight)
A seamless belt having a thickness of 40 μm was obtained in the same manner as in Example 1 except that The seamless belt had a shrinkage of 7% in the axial direction and a shrinkage of 10% in the circumferential direction. In addition, the film thickness of this seamless belt is 40 ± 5μ in all, measured at four points in the circumferential direction at both ends and in the center.
It was in the range of m and had a uniform film thickness.

Example 3 A seamless belt having a thickness of 80 μm was prepared in the same manner as in Example 1 except that 22.2 g of an aromatic polyimide varnish (manufactured by Ube Industries, Ltd., solid content concentration as polyamic acid: 18% by weight) was replaced. Obtained. The seamless belt had a shrinkage rate of 10% in the cylindrical axis direction and a shrinkage rate of 14% in the circumferential direction. In addition, the film thickness of this seamless belt is
Measurements were made at four points in the circumferential direction at the center, and all were within a range of 80 ± 5 μm, and the film thickness was uniform.

Comparative Example 1 22.2 g of a solution of aromatic polyimide varnish (manufactured by Ube Industries, Ltd., solid content concentration as polyamic acid: 18% by weight) was used as a cylindrical mold (inner diameter φ110 mm × outer diameter φ130 mm × length 360). mm)
Injected into, the rotation speed 2500rpm, air flow 0.7 liter /
The film was rotated at an air temperature of 80 ° C. for a minute to obtain a film containing polyamic acid as a main component. Insert this film into an inner cylinder (outer diameter φ 90 mm × 360 mm) whose surface is mirror-finished, and
It was placed in an oven at 50 ° C., left for 60 minutes and then taken out to obtain a seamless belt having a thickness of 80 μm made of a mixed resin film. The shrinkage factor of this seamless belt in the cylinder axis direction is 1
It was 7% and the shrinkage ratio in the circumferential direction was 17%. The film thickness of this seamless belt was 80 ± 5 μm when measured at four points in the circumferential direction at both ends and the central part, and it was a uniform film thickness.

[0025]

EFFECTS OF THE INVENTION In the method for producing a seamless belt according to the present invention, in the firing step, the cylindrical resin film peeled from the inner wall of the cylindrical mold has an inner cylinder having a diameter smaller than the film diameter, particularly the outer peripheral surface is roughened. Since the inner cylinder is inserted and fired, the shrinkage rate of the seamless belt in the cylinder axial direction can be suppressed. As a result, a seamless belt with excellent dimensional accuracy can be obtained by a simple method. The seamless belt manufacturing apparatus according to the present invention includes a rotating cylindrical mold, two fixed cylinders each having a V ring that slides on both ends of the cylindrical mold directly or through open lids, and the fixed cylinder. Since the blower means provided on one side of the cylinder and the heat source provided between the blower means and the V ring are provided, a seamless belt with a uniform film thickness, reduced production loss, and high yield can be obtained. To be Further, the solvent recovery rate can be increased by reducing the diameter of at least one of the fixed cylinders.

[Brief description of drawings]

FIG. 1 is a perspective view of a seamless belt.

FIG. 2 is a cross-sectional view of a film forming apparatus using a centrifugal casting method.

FIG. 3 is a cross-sectional view of a film forming apparatus in which one of the fixed cylinders has a reduced diameter.

[Explanation of symbols]

1 seamless belt 2 cylindrical mold 3 open lid 4 O-ring 5 V ring 6 fixed cylinder 7 Blower means 8 heat sources

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI G03G 15/20 101 G03G 15/20 101 // B29K 79:00 B29K 79:00 (56) Reference JP 2002-156850 (JP , A) JP 2002-14543 (JP, A) JP 4-189827 (JP, A) JP 2000-153530 (JP, A) JP 2001-158023 (JP, A) JP 2000-271946 ( JP, A) JP 2002-72703 (JP, A) JP 2001-215821 (JP, A) JP 2001-179747 (JP, A) JP 2001-1353 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B29C 41/04 B29C 41/34 B29C 41/48 C08L 79/04 C08L 79/08 G03G 15/20 101

Claims (4)

(57) [Claims] 1. An aromatic polyimide resin or an aromatic polybenzimidazole resin having a shrinkage ratio of 15% or less at the time of firing after film formation in the cylindrical axial direction and the circumferential direction and a film thickness variation of ± 5 μm or less. A method for producing a seamless belt made of a mixed resin cylindrical film, comprising a step of injecting the aromatic polyimide resin and an aromatic polybenzimidazole resin forming solution into a rotating cylindrical mold, and the cylinder by centrifugal force. A step of forming a resin film on the inner wall of the mold, and a step of inserting an inner cylinder having a diameter smaller than the film diameter into the cylindrical resin film exfoliated from the inner wall and firing at a firing temperature of 300 to 350 ° C. A method for manufacturing a seamless belt, comprising: 2. The outer peripheral surface of the inner cylinder has a Ra of 5 to 10 μm.
The method for producing a seamless belt according to claim 1, wherein the seamless belt is roughened. 3. The seamless belt according to claim 1, wherein the outer diameter of the inner cylinder is 3 to 10 mm smaller than the diameter of the resin film formed by the rotary centrifugation method. Manufacturing method. 4. A rotating cylindrical mold, and two fixed cylinders provided with open lids fixed to both ends of the cylindrical mold or V-rings directly sliding on both ends of the cylindrical mold. At least one of the fixed cylinders has a diameter smaller than the diameter of the fixed cylinder at the position where the V ring is disposed, and is provided between one of the fixed cylinders and a blower means, and the blower means and the V ring. A resin film forming means including a heat source, an inner cylinder having a diameter smaller than the diameter of the formed cylindrical resin film, and a means for firing the cylindrical resin film by inserting the inner cylinder. An apparatus for producing a seamless belt, comprising: