JP3011204B1 - Manufacturing method for tubular objects - Google Patents

Abstract

An object of the present invention is to provide a tubular member having a good wall thickness accuracy, a small resin loss, a crown shape, an inverted crown shape, or a tapered shape and a substantially uniform film thickness. . SOLUTION: A liquid heat-resistant resin is applied to an outer surface of a core which is a molding die, and the applied liquid heat-resistant resin is applied until the formed coating layer has a strength at least capable of maintaining a structure as a tubular object. After solidifying or curing, in a method for producing a tubular article including a step of removing the tubular article from the core body,
(1) A crown, inverted crown, or tapered core is used as the core, and (2) a liquid heat-resistant resin is continuously supplied to the outer surface of the core by a dispenser while rotating the core. In addition, by moving the dispenser supply section at a constant speed in the rotation axis direction of the core, the supplied liquid heat-resistant resin is spirally wound around the outer surface of the core to form a coating layer having a uniform thickness. A method for producing a tubular article, and a tubular article.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a tubular article, and more particularly, to applying a liquid heat-resistant resin to the outer surface of a core such as a cylindrical mold or a cylindrical mold, and applying the applied liquid. The present invention relates to a method for producing a crown-shaped or inverted crown- shaped tubular article by solidifying or hardening a heat-resistant resin.

[0002]

2. Description of the Related Art Heat-resistant films are used for various purposes such as flexible printed circuit boards, insulators for electric equipment, and magnetic tapes. Among these heat-resistant films, tubular heat-resistant films are used as fixing belts and the like in image forming apparatuses such as electrophotographic copying machines, facsimiles, and printers. That is, in an image forming apparatus such as an electrophotographic copying machine, as a method of fixing a toner image on recording paper by heating and melting toner on recording paper (copy paper), a film-shaped endless fixing belt is used. There is a method in which the toner on the recording paper is directly heated by a heater. This fixing belt has heat resistance,
Since it is required to be excellent in strength, Young's modulus, etc., generally, a tubular article made of a polyimide film having excellent heat resistance and mechanical strength is used.

[0003] As a method for producing a tubular product made of a polyimide film, a polyimide precursor solution is applied to the outer peripheral surface of a core such as a cylindrical mold or the inner peripheral surface of a cylindrical mold by a dipping method (immersion method). Then, the excess resin is removed by dropping a die (in the case of outer peripheral surface application) or a bullet-shaped object (in the case of inner peripheral surface application) by its own weight from the upper end of the application portion, and after a predetermined thickness, the coating layer is formed. Is heated to form a cured polyimide film (JP-A-7-164456, JP-A-62-19).
437).

However, in the conventional method for producing a tubular article, the heating after the formation of the coating layer reduces the viscosity of the heat-resistant resin before curing, so that the coating layer sags and the thickness tends to vary. When dipping, the top surface of the coating layer may be slanted, and when the dice or bullet-shaped object starts falling, the circumferential position of these objects is not stable. Inability to do so, it is necessary to remove the resin layer about 1 cm at the lower end of the mold after application to the lower end by dipping to make it easier to remove the mold, shafts such as crown-shaped and inverted crown-shaped (drum-shaped) There are problems such as the inability to manufacture a tubular article having a thickness changed in the direction and a tubular article having a circumferential strength greater than the axial strength.

Accordingly, the present inventors have conducted intensive studies to overcome the above-mentioned problems, and as a result, have applied a liquid heat-resistant resin containing an inorganic filler, if desired, to the outer surface or inner surface of a core as a molding die. Until the formed coating layer has a strength capable of maintaining at least the structure of the tubular object, after solidifying or curing the applied liquid heat-resistant resin, removing the tubular object from the core body. In the manufacturing method, a liquid heat-resistant resin having a viscosity at 25 ° C. of 10 to 15,000 poise is continuously supplied to the outer surface or the inner surface of the core body by a dispenser while rotating the core body, and the supply portion of the dispenser is supplied. When the supplied liquid heat-resistant resin is spirally wound to form a coating layer by moving the core in the rotation axis direction, the thickness accuracy is good and the resin loss is small. We are obtained the tubing (JP-A-9-85756). According to this method,
By using a liquid heat-resistant resin containing a needle-like or scale-like inorganic filler, it is also possible to obtain a tubular article having a strength in the circumferential direction larger than that in the axial direction.

In particular, according to this method, the amount of the liquid heat-resistant resin supplied by the dispenser and / or the moving speed of the dispenser supply unit are arbitrarily changed while the dispenser supply unit moves in the direction of the rotation axis. ,
An arbitrary thickness distribution can be provided in the axial direction of the tubular object. Thereby, for example, it is possible to easily manufacture an inverted crown-shaped tubular material having a thin central portion in the axial direction and thickened both ends, or a crown-shaped tubular material having a thick central portion in the axial direction and thinned at both ends. Can be. When the crown-shaped or inverted crown-shaped tubular material obtained by this method is used as a fixing belt of an image forming apparatus, it is effective for preventing wrinkles of copy paper. However, since these crown-shaped or inverted-crown-shaped tubular articles have different thicknesses in the axial direction, there is a problem in that heat conduction from the heater has a difference in the longitudinal direction, and fixing unevenness is likely to occur. Was.

[0007]

An object of the present invention is to provide a wall thickness accuracy is good, small resin loss, yet crowned or
Other is a reverse crown shape tubing is that the film thickness to provide a substantially uniform tubing. The present inventors have conducted intensive studies to overcome the problems of the conventional technology,
While supplying the liquid heat-resistant resin to the outer surface of the core rotating in the circumferential direction by the dispenser, the supply portion of the dispenser is moved in the rotation axis direction of the core to supply the supplied liquid heat-resistant resin to the outer surface of the core. In a method for manufacturing a tubular article including a step of spirally winding to form an application layer, a crown-shaped or inverted crown- shaped core is used as a core, and a dispenser supply unit is connected to a rotation axis of the core. It has been found that by moving at a constant speed in the direction, a crown-shaped or inverted-crown- shaped tubular material having a uniform film thickness can be obtained.

[0008] Conventionally, when a tubular body made of synthetic resin is formed using a core, a core having a constant longitudinal diameter such as a cylindrical mold or a cylindrical mold has been used. The reason is that when the diameter in the longitudinal direction changes, it is difficult to remove the tubular article from the core body, and it is difficult to form a tubular article having a uniform film thickness. On the contrary,
According to the production method of the present invention, the film thickness is uniform crowned or
Others can be obtained inverted crown shaped tubing. Also,
By controlling the shape and crown ratio (described later) of the core, it is possible to solve the problem of removing the molded tubular article from the core. The present invention has been completed based on these findings.

[0009]

According to the present invention, a liquid heat-resistant resin is applied to the outer surface of a core as a molding die, and the formed coating layer has a strength capable of maintaining at least the structure as a tubular object. The method for producing a tubular article includes a step of taking out the tubular article from the core after solidifying or curing the applied liquid heat-resistant resin until having the following. (1) As the core, the formula (1) [(a- b) / a] × 100 (1) (where a is the outer diameter of the end portion, and b is the outer diameter of the central portion.
It is. ) Is 0.05.
Using the 0.5% and is crowned or inverted crown shaped core, (2) while rotating the core body, the liquid of the heat-resistant resin while continuously supplied by a dispenser on the outer surface of the core, the dispenser By moving the supply section at a constant speed in the rotation axis direction of the core, the supplied liquid heat-resistant resin is spirally wound around the outer surface of the core to form a coating layer having a uniform thickness. producing how the tubing is provided.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the manufacturing method of the present invention, the outer surface of a substantially cylindrical or cylindrical core body rotating in a circumferential direction, the outer surface of the core body being shaped like a crown or an inverted crown is described. The liquid heat-resistant resin is continuously supplied by a dispenser, and the supply part of the dispenser is moved at a constant speed in the direction of the rotation axis of the core, so that the liquid heat-resistant resin is spirally formed on the outer surface of the core with a uniform thickness. And apply it by winding. As shown in FIG. 1, while rotating the core 4 in the circumferential direction, the liquid heat-resistant resin is continuously supplied from the supply unit 2 of the dispenser 1, and the supply unit 2 is moved in the rotation axis direction of the core. Then, the supplied liquid heat-resistant resin 3 is spirally wound to form a coating layer. Adjacent portions of the liquid heat-resistant resin wound in a spiral form combine to form a uniform coating layer. The supply part of the dispenser is usually a nozzle, and as shown in FIG. 2, the tip of the nozzle 2 is formed obliquely, and the center of the tip (liquid discharge port) contacts the outer surface of the core 4. However, it is preferable to set the nozzle position so as to move in the rotation axis direction of the core. The inner diameter of the nozzle (liquid discharge port) is usually 0.5 to 5 mm, preferably 1 to 5 mm.
It is about 3 mm.

The moving speed of the dispenser and the rotating speed of the core body are adjusted so that the liquid heat-resistant resins applied in a spiral contact with each other to form a uniform coating layer. Apply heat resistant resin. After this coating step, the applied liquid heat-resistant resin is solidified or cured until the coating layer has a strength capable of maintaining at least the structure of the tubular object, and then the tubular object is taken out from the core. Thereby, a tubular object can be obtained.
As shown in FIG. 3, the shape of the core body is an inverted crown shape in which the central portion in the axial direction is thinner and the both end portions are thicker (the outer diameter becomes smaller toward the central portion), and as shown in FIG. There is also a crown-shaped one having a thicker central portion in the axial direction and a thinner end portion (a shape having a larger outer diameter toward the central portion ) . These cores can be appropriately selected depending on the use and purpose of the tubular article. For example, in order to use a tubular material as a fixing belt and to prevent wrinkles of copy paper, a crown-shaped or inverted crown-shaped tubular material is usually preferable.

When the tapered core shown in FIG. 5 is used, the tubular article can be removed from the end having the smaller diameter after molding. On the other hand, in the case of a crown-shaped or inverted crown-shaped core, the sizes of the crown and the inverted crown are preferably determined in consideration of the difference in the coefficient of thermal expansion between the core and the heat-resistant resin. More preferably, the crown ratio is controlled. That is, when the inverted crown-shaped core shown in FIG. 3 and the crown-shaped core shown in FIG. 4 are used, the crown ratio is controlled in order to easily remove the tubular article after molding. Is more preferable. Here, the crown ratio is defined by the equation (1), where a is the outer diameter of the end of the core (= the inner diameter of the end of the tubular body) and b is the outer diameter of the center of the core (= the inner diameter of the center of the interstellar object). [(Ab) / a] x 100 means a value defined by (1).

In the case of the inverted crown-shaped core shown in FIG. 3 (corresponding to the inverted crown-shaped tubular body), the crown ratio becomes a positive value, but the crown-shaped core shown in FIG. )), The crown ratio is a negative value. In the present invention, it is necessary to adjust the shape of the core body (therefore, the shape of the tubular body) so that the absolute value of the crown ratio is 0.5% or less. It is preferable for facilitating the mold. The crown ratio is 0 . 05-0.5% ,
Good Mashiku is 0.1 to 0.4%. Also, | ab |
Is defined as a crown amount. In a tubular article having a size for normal fixing belt use (for example, an inner diameter of about 20 to 25 mm), the crown amount is preferably 100 μm or less, more preferably 80 μm or less. It is desirable from the viewpoint of ease of operation.

The core material used in the present invention includes, for example, metals such as aluminum, aluminum alloy, iron and stainless steel; ceramics such as alumina and silicon carbide;
Heat-resistant resins such as polyimide, polyamideimide, polybenzimidazole, and polybenzoxazole; and the like. In order to improve the release property of the core, it is preferable to apply a release agent made of silicone oil or the like or to coat the core with ceramics. As ceramics, silica, alumina, coated by sol-gel method,
Zirconia and silicon nitride; alumina and zirconia coated by thermal spraying; and aluminum nitride coated by sputtering. Among these, ceramic coating by a sol-gel method, which does not require an expensive device and facilitates the coating operation, is preferred.

The liquid heat-resistant resin used in the present invention has a viscosity at 25 ° C. of 10 to 15,000 poise (ps).
Is preferred. If the viscosity is too high, the part where the liquid heat-resistant resins wound and applied in a spiral form come into contact with each other and become thinner than other parts, and the surface of the heat-resistant resin layer (coating layer) tends to have irregularities. If the viscosity of the liquid heat-resistant resin is too low, dripping or repelling occurs during application or drying, and it becomes difficult to form a tubular material. By setting the viscosity of the liquid heat-resistant resin to an appropriate range, there is no dripping or repelling, and after application, the liquid moves due to gravity or centrifugal force, the liquid surface becomes smooth, and the heat-resistant resin layer without irregularities Can be formed. In order to reliably prevent dripping, flipping, and formation of irregularities, it is more preferable that the viscosity of the liquid heat-resistant resin used is 100 to 3000 ps.

The liquid heat-resistant resin used in the present invention means a resin which can be continuously used at 100 ° C. or higher and can be molded in a liquid state when a tubular article is formed. That is, it refers to an uncured liquid thermosetting resin, a solution in which an uncured thermosetting resin is dissolved in a solvent, or a solution in which a thermoplastic resin is dissolved in a solvent. In addition, the liquid heat-resistant resin used in the present invention also includes those obtained by adding an inorganic filler to the above resin. Specific examples of the heat-resistant resin include, for example, polyimide, polyamideimide, polybenzimidazole, polybenzoxazole, polyphenylene sulfide, polysulfone, polyetheretherketone, polyethersulfone, polyetherimide, polyarylate, liquid crystal polymer, epoxy resin, etc. Is mentioned. Among these heat-resistant resins, the production method of the present invention can be preferably applied particularly to polyimide. Polyimide is generally used as a solution of a polyimide precursor (polyimide varnish), applied to the surface of a molding die, and then cured by heating (imidization) to produce a strong thin film.

As the inorganic filler to be contained in the liquid heat-resistant resin, for example, boron nitride, alumina,
Silicon carbide, potassium titanate, aluminum nitride, mica,
Examples thereof include silica, titanium oxide, talc, calcium carbonate, and the like. The amount of the inorganic filler is not particularly limited as long as the viscosity of the liquid heat-resistant resin falls within the above preferred range and can be discharged by a dispenser, and can form a uniform coating layer. Can be determined. In the manufacturing method according to the present invention, a liquid heat-resistant resin is continuously supplied to the outer surface of the core body by a dispenser while rotating the core body so that the thermal conductivity of the tubular object does not vary in the longitudinal direction. At the same time, by moving the supply portion of the dispenser at a constant speed in the direction of the rotation axis of the core, the supplied liquid heat-resistant resin is spirally wound around the outer surface of the core to form a coating layer having a uniform thickness. Thereby, a crown-shaped or inverted-crown- shaped tubular material having a substantially uniform film thickness can be obtained.

The tubular material used as the fixing belt includes alumina, silicon carbide,
It is preferable to add an inorganic filler such as boron nitride or silica, but depending on the type of the inorganic filler, the affinity with the liquid heat-resistant resin may not be sufficient. When such a liquid heat-resistant resin is applied to the coating method of the present invention, a slightly dark portion may be formed along the spiral coating path to form a striped pattern. The thickness may differ between the dark part and the thin part, resulting in unevenness. This is considered to be due to uneven dispersion of the inorganic filler. The generation of this stripe pattern can be prevented by the following method. That is, the liquid discharge port of the dispenser supply unit is in contact with the heat-resistant resin layer applied to the core, and the moving speed V (mm / sec) and the rotational speed R (rotation / sec) of the cylindrical core are By performing the application under the conditions in the range represented by the relational expression (2), it is possible to prevent the occurrence of the stripe pattern and the unevenness due to the stirring effect of the liquid near the liquid discharge port. (V / R) <1.5 (mm / rotation) (2) When V / R is 1.5 mm / rotation or more, the stirring effect in the vicinity of the liquid discharge port alone is not sufficient, and stripes and irregularities occur. May be.

In consideration of cost reduction, the coating time is preferably short. When applying according to the relational expression (2),
The application time can be shortened by increasing the number of rotations of the core, but the number of rotations has an upper limit because it is necessary to prevent the liquid from scattering due to centrifugal force. In such a case, by forming the liquid discharge port in a specific shape, it is possible to reduce the coating time and prevent the occurrence of the stripe pattern and the unevenness. That is, the liquid discharge port of the dispenser supply unit is tubular, and its wall thickness t (mm) is in the following range. 0.3 mm <t <3.0 mm (3) It is considered that the stirring effect in the vicinity of the liquid discharge port is caused by the end face of the wall of the tubular discharge port coming into contact with the resin on the core. It has been experimentally found that a sufficient stirring effect can be obtained when the width of the end face of the wall is in the above range, and the wall thickness t of the tubular liquid discharge port is less than 0.3 mm or 3.0 mm. If it is excessive, a sufficient stirring effect cannot be obtained. The wall thickness t of the tubular liquid discharge port is more preferably 0.5-2.
0 mm.

A plastics tube, a rubber tube, a metal tube, or the like can be preferably used for the liquid discharge port of the dispenser supply unit. Among these, a tube made of polytetrafluoroethylene (PTFE) or tetrafluoroethylene / perfluoroalkylvinyl ether copolymer (PFA) is particularly suitable because it has appropriate rigidity and hardly damages the core. Can be used. Using a liquid heat-resistant resin containing scale-like inorganic fillers having different needle-like or vertical and horizontal lengths in the plane of the plate, when the tubular material is produced by the production method of the present invention, the inorganic fillers are oriented in the circumferential direction. A tubular article having a circumferential strength greater than the axial strength can be manufactured. When such a tubular article is used, for example, as a fixing belt, it is useful because it is strong against circumferential tension and circumferential fatigue. The needle-like filler is not limited to this,
Examples include potassium titanate whiskers and silicon carbide whiskers. Examples of the scaly filler include, but are not limited to, boron nitride and mica.

The tubular material obtained by the production method of the present invention has a uniform thickness and the formula (1) [(ab) / a] × 100 (1) And b is the inner diameter of the central part.) The absolute value of the crown ratio defined by
A crown-shaped or inverted crown-shaped tubular
You. The tubular article of the present invention is particularly suitable as a fixing belt in an image forming apparatus such as an electrophotographic copying machine, a facsimile, and a printer.

[0022]

The present invention will be described more specifically with reference to the following examples.

Example 1 An aluminum cylinder having an outer diameter of 24 mmφ was used as a mold and had a diameter of 50 μm (the above-mentioned | a−
b |) was used, and the outer surface thereof was coated with ceramics. While rotating the inverted crown-shaped core (rotational speed = 800 rpm), the nozzle set in the resin supply section of the dispenser was brought into contact with the outer surface of the core. As a liquid heat-resistant resin, polyimide varnish manufactured by Ube Industries (Ube Industries: U Varnish-S; viscosity: 10)
A solution containing 25% by weight of boron nitride was used. In this state, while the resin is supplied from the nozzle in a fixed amount (discharge amount = 0.21 cc / s), the nozzle is moved at a constant speed (traverse speed = 10 mm /
The substrate was moved in s) to apply a heat-resistant resin. The viscosity is B
It was measured at a liquid temperature of 25 ° C. and a rotor rotation speed of 6 rpm with a mold viscometer. The dispenser nozzle
A PTFE tube having an inner diameter of 2 mm and an outer diameter of 4 mm was used. As shown in FIG. 2, the tip of the tube 2 was cut off at an angle of 45 °, and the nozzle position was set such that the center of the cut surface moved in the axial direction of the core while contacting the outer surface of the core 4.

The nozzle is brought into contact with a position 20 mm from the right end of the inverted crown-shaped core, and the resin supply is started. When the nozzle reaches the position 20 mm from the left end of the inverted crown-shaped core, the resin is supplied. After stopping, the nozzle was separated from the core. Next, the core was rotated and gradually heated to 400 ° C., and after cooling, the solidified coating resin was removed from the mold as a tubular material. By the above operation, an inverted crown-shaped tubular body having a predetermined length, an inner diameter of 24 mmφ, a wall thickness of 50 μm, a crown amount of 50 μm, and a uniform thickness was obtained. This inverted crown tube is about 2
Only by cutting off mm, molding was possible with almost no resin loss. The thickness variation of the obtained inverted crown-shaped tubular article was ± 1.0 μm, and the thickness was substantially uniform. The outer shape of the tubular object was measured with a roughness meter,
No undulations or irregularities were seen. The appearance was good without any stripes. When the outer surface of the inverted crown-shaped tubular article obtained above was coated with a fluororesin, and used as a fixing film of a laser printer,
Even when the copy paper was thin paper, no paper wrinkles were generated and the fixing was very uniform. In the above manufacturing process, if the crown amount of the core body was more than 120 μm (crown ratio = 0.5%), it was difficult to remove the molded tubular article from the core body.

[0025]

According to the present invention, the thickness accuracy is good, the resin loss is small, and the crown shape or the inverted crown shape is obtained.
, Wherein the thickness of the tube is substantially uniform. According to the production method of the present invention, while continuously supplying the liquid heat-resistant resin to the outer surface of the rotating crown-shaped or inverted crown- shaped core body by a dispenser, the supply unit is rotated at a constant speed in the rotation axis direction. Since the coating method of moving is used, the accuracy of the thickness of the tubular material is remarkably improved, the loss of the resin is small, and a crown-shaped or inverted crown- shaped tubular material having a substantially uniform film thickness can be obtained. . By using a liquid heat-resistant resin containing a needle-like or scale-like inorganic filler, it is possible to produce a tubular article having a strength in the circumferential direction larger than that in the axial direction.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a coating method using a dispenser of the present invention.

FIG. 2 is an explanatory diagram of a shape of a nozzle tip and a contact position between a nozzle and a core body in a coating method of the present invention.

FIG. 3 is a schematic longitudinal sectional view of an inverted crown-shaped core body.

FIG. 4 is a schematic cross-sectional view of a crown-shaped core body in a longitudinal direction.

FIG. 5 is a schematic cross-sectional view of a tapered core in a longitudinal direction.

[Explanation of symbols]

 1: dispenser 2: nozzle 3: liquid heat-resistant resin (spirally wound and applied) 4: core

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-9-85756 (JP, A) JP-A-8-216267 (JP, A) JP-A-4-59343 (JP, A) JP-A 64-64 30734 (JP, A) JP-A-63-168338 (JP, A) JP-A-60-178030 (JP, A) JP-A-3-34816 (JP, A) (58) Fields investigated (Int. ⁷ , DB name) B29C 41/08 B29C 41/36 B29C 41/38 B29C 41/42

Claims (1)

(57) [Claims] 1. A liquid heat-resistant resin is applied to the outer surface of a core which is a molding die, and the liquid heat-resistant resin is applied until the formed coating layer has a strength capable of maintaining at least a structure as a tubular object. After solidifying or hardening, a method of manufacturing a tubular article including a step of taking out the tubular article from the core body, wherein (1) the core is represented by the formula (1) [(ab) / a] × 100 (1) (Where a is the outer diameter of the end, and b is the outer diameter of the center.
It is. ) Is 0.05.
Using the 0.5% and is crowned or inverted crown shaped core, (2) while rotating the core body, the liquid of the heat-resistant resin while continuously supplied by a dispenser on the outer surface of the core, the dispenser By moving the supply section at a constant speed in the rotation axis direction of the core, the supplied liquid heat-resistant resin is spirally wound around the outer surface of the core to form a coating layer having a uniform thickness. A method for producing a tubular article.