JP2004195989A - Manufacturing process of tubing, and tubing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a novel tubing and manufacturing process thereof, which allow a good precision in wall thickness, an optional wall thickness profile along the axial direction as needed, and an orientation to the peripheral direction of an inorganic filler. <P>SOLUTION: The manufacturing process of the tubing comprises the steps of supplying a heat-resistant liquid resin having a viscosity of 100 to 15,000 poises at 25°C continuously to the outer or inner surface of a core body by a dispenser while rotating the core body, and moving a supply unit of the dispenser to the rotating axis direction of the core body, while bringing a liquid spout center of the supply unit of the dispenser bearing the liquid spout into contact with the outer or inner surface of core body to thereby wind the supplied heat-resistant liquid resin spirally to form a coating layer. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a method for producing a tubular article, and more specifically, a liquid heat-resistant resin is applied on the surface of a core such as a cylindrical mold or a cylindrical mold, and the applied liquid heat-resistant resin is solidified or The present invention relates to a method for producing a tubular article by curing. The present invention also relates to the tubular article obtained in this way.

  Heat-resistant films are used in various applications 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 for electrophotographic copying machines, facsimile machines, printers and the like. That is, in an electrophotographic copying machine or the like, as a method of heating and melting the toner on the recording paper to fix the toner image on the recording paper, a heater is provided on the recording paper by a heater through a film-like endless fixing belt (tubular material). There is a method of directly heating the toner. Since the fixing belt is required to be excellent in heat resistance, strength, Young's modulus and the like, a polyimide film excellent in heat resistance and mechanical strength is generally used.

  As a method for producing a tubular material 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). 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) from the upper end of the application part by its own weight. There has been proposed a method of forming a cured film of polyimide by using a method (Patent Documents 1 and 2).

  By the way, in the conventional method for manufacturing a tubular article, improvement has been particularly demanded for the following two points. The first point is that since the viscosity of the heat-resistant resin before curing is reduced by heating after forming the coating layer, depending on the viscosity of the heat-resistant resin and the heating conditions, the coating layer may sag, and as a result, the thickness may vary. That was the case. The second point is that the upper end surface of the coating layer may be inclined at the time of dipping, or at the start of the fall of a die or a bullet-shaped object, the circumferential position of these fallen objects is not stable. cm cannot be used as a product, and it is necessary to remove about 1 cm of resin at the lower end of the mold after application to the lower end by dipping to facilitate removal from the mold. There is resin loss. Further, in the conventional method of manufacturing a tubular article, for example, a tubular article having a thickness changed in the axial direction such as a crown or a drum, and a tubular article having a circumferential strength larger than the axial strength can be manufactured. Did not.

  The method for producing the tubular article is not limited to polyimide, but other liquid heat-resistant resins, for example, an uncured liquid thermosetting resin, an uncured thermosetting resin solution, or a thermoplastic resin solution. It is also applicable. However, when a tubular article is manufactured using another liquid heat-resistant resin, there is a problem of thickness variation and resin loss as in the case of using polyimide. In addition, it is the same that a tubular article whose thickness changes in the axial direction or a tubular article whose circumferential strength is greater than the axial strength cannot be manufactured.

JP-A-7-164456 JP-A-62-19437

  An object of the present invention is to produce a novel tubular article having a good wall thickness accuracy, a small resin loss, an optional thickness distribution in an axial direction as required, and an inorganic filler oriented in a circumferential direction. It is to provide a method.

  Another object of the present invention is to provide a tubular article containing an inorganic filler and having a strength in the circumferential direction larger than that in the axial direction.

  The present inventors have conducted intensive studies on various methods for producing tubular articles, and as a result, while supplying a liquid heat-resistant resin to the outer surface or the inner surface of a core rotating in the circumferential direction by using a dispenser, the supply portion of the dispenser is connected to the core. By moving the supplied liquid heat-resistant resin spirally to form a coating layer by moving it in the direction of the rotation axis, it is possible to improve the wall thickness accuracy and reduce the resin loss. I found it.

  According to this method, a tubular article whose thickness changes in the axial direction can be obtained by adjusting the amount of the liquid heat-resistant resin supplied from the dispenser, the moving speed of the dispenser supply section in the rotation axis direction, and the like. Further, 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. The present invention has been completed based on these findings.

  According to the present invention, a liquid heat-resistant resin containing an acicular or scaly inorganic filler is applied to the outer surface or inner surface of a core body which is a molding die, and the formed coating layer has a structure as at least a tubular object. Until having a strength that can be held, after solidifying or curing the applied liquid heat-resistant resin, in a method for manufacturing a tubular article including a step of removing the tubular article from the core, while rotating the core, the core A liquid heat-resistant resin having a viscosity of 100 to 15000 poise at 25 ° C. is continuously supplied to an outer surface or an inner surface by a dispenser, and the center of the liquid discharge port of the dispenser supply section having the liquid discharge port is a core body. By moving the supply portion of the dispenser in the rotation axis direction of the core while contacting the outer surface or the inner surface of the core, the supplied liquid heat-resistant resin is spirally wound to form a coating layer. Method of manufacturing a tubular product which comprises bringing made is provided.

  Further, according to the present invention, there is provided a tubular article made of a heat-resistant resin containing a needle-like or scale-like inorganic filler, wherein the strength in the circumferential direction is larger than the strength in the axial direction.

  According to the present invention, 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.

  In the production method of the present invention, while continuously supplying a liquid heat-resistant resin having a viscosity of 100 to 15000 ps to an outer surface or an inner surface of a cylindrical or cylindrical core rotating in a circumferential direction, the dispenser is supplied. The portion is moved in the direction of the rotation axis of the core body, and the liquid heat-resistant resin is spirally wound and applied.

  As shown in FIG. 1, while rotating the cylindrical core body 4 in the circumferential direction, the liquid heat-resistant resin is continuously supplied from the supply section 2 of the dispenser 1, and the supply section 2 is rotated in the rotation axis direction of the core body. 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 body 4. It is preferable to set the nozzle position so as to move in the direction of the rotation axis of the core. The inner diameter of the nozzle (liquid discharge port) is usually 0.5 to 5 mm, preferably about 1 to 3 mm.

  Adjust the moving speed of the dispenser and the rotation speed of the core 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 at least a strength capable of maintaining the structure as a tubular object, and then the tubular object is taken out from the core body. Thereby, a tubular object can be obtained.

  The viscosity of the liquid heat-resistant resin at 25 ° C. needs to be 100 to 15000 poise (ps). When the viscosity exceeds 15000 ps, the portion where the liquid heat-resistant resins wound in a spiral shape are in contact with each other and connected to each other becomes thinner than other portions, and irregularities occur on the surface of the heat-resistant resin layer (coating layer). If the viscosity of the liquid heat-resistant resin is less than 100 ps, dripping or repelling occurs during application or drying, and it is difficult to form a tubular material. By setting the viscosity of the liquid heat-resistant resin to 100 to 15000 ps, there is no dripping or repelling, and after application, the liquid moves due to gravity or centrifugal force, the liquid surface becomes smooth, and a heat-resistant resin layer without irregularities is formed. can do. In order to reliably prevent dripping, repelling, and formation of irregularities, the viscosity of the liquid heat-resistant resin used is preferably set to 100 to 3000 ps.

  The liquid heat-resistant resin used in the present invention refers to a resin that can be used continuously 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.

  Specific examples of the heat-resistant resin include polyimide, polyamideimide, polybenzimidazole, polybenzoxazole, polyphenylene sulfide, polysulfone, polyetheretherketone, polyethersulfone, polyetherimide, polyarylate, liquid crystal polymers, epoxy resins, and the like. No. 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.

  The shape of the core used in the present invention is not particularly limited, but a column or a cylinder can be preferably used. Examples of the material of the core used in the present invention include metals such as aluminum, aluminum alloys, iron and stainless steel; ceramics such as alumina and silicon carbide; heat-resistant resins such as polyimide, polyamideimide, polybenzimidazole and polybenzoxazole; Is mentioned.

  Further, 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. Examples of ceramics include silica, alumina, zirconia, and silicon nitride coated by a sol-gel method; alumina and zirconia coated by a thermal spray method; and aluminum nitride coated by a sputtering method. Among these, ceramic coating by a sol-gel method, which does not require an expensive device and facilitates the coating operation, is preferred.

  In the manufacturing method according to the present invention, by changing the amount of the liquid heat-resistant resin supplied by the dispenser or the moving speed of the dispenser supply part arbitrarily while the dispenser supply part moves in the rotation axis direction, the axial direction of the tubular object is changed. Can have an arbitrary thickness distribution. For example, it is possible to easily manufacture a crown-shaped tubular material having a thin central portion in the axial direction and thickened both end portions.

An inorganic filler such as alumina, silicon carbide, boron nitride, or silica may be added to a tubular material used as a fixing belt in order to improve thermal conductivity. Depending on the type of the inorganic filler, the affinity with the liquid heat-resistant resin may not be sufficient, and when such a liquid heat-resistant resin is applied to the coating method of the present invention, along the spiral coating path, slightly. In some cases, a dark portion is formed to form a striped pattern. In a severe case, the dark portion and the thin portion have different thicknesses and may be uneven. This is considered to be due to uneven dispersion of the inorganic filler. The generation of the 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 low. By performing the application under the conditions in the range represented by the relational expression (1), 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) (1)
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 a stripe pattern and unevenness may occur.

  In consideration of cost reduction, the coating time is preferably short. When the coating is performed according to the relational expression (1), the coating time can be shortened by increasing the rotation speed of the core body. However, it is necessary to prevent the liquid from scattering due to centrifugal force. There is.

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 has a tubular shape, and its wall thickness t (mm) is in the following range.
0.3 mm <t <3.0 mm (2)
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 body. 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 to 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 preferable because it has appropriate rigidity and hardly damages the core. Can be used.

  When using a liquid heat-resistant resin containing scale-like inorganic fillers having different needle-like or plate-like vertical and horizontal lengths to produce a tubular article 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 material is used as, for example, a fixing belt, it is useful because it is strong against circumferential tension and circumferential fatigue. Examples of the needle-like filler include, but are not limited to, potassium titanate whiskers and silicon carbide whiskers. Examples of the flaky filler include, but are not limited to, boron nitride and mica.

  Hereinafter, the present invention will be described more specifically with reference to Reference Examples and Examples.

[Reference Example 1]
An aluminum cylinder having an outer diameter of 20 mmφ coated with ceramics was used as a mold, and a nozzle set in a resin supply section of a dispenser was brought into contact with the outer surface of the core body while rotating the cylindrical mold. As the liquid heat-resistant resin, a mixture obtained by adding 10 parts of alumina powder (AL-45H) manufactured by Showa Denko to 100 parts of polyimide varnish manufactured by Ube Industries, and uniformly mixing them was used. In this state, the resin was applied by moving the nozzle at a constant speed in the direction of the rotation axis of the core body while supplying the resin from the nozzle at a constant rate. The coating conditions at this time are as shown in Table 1. The viscosities of the resins in Table 1 are measured by a B-type viscometer at a liquid temperature of 25 ° C. and a rotor rotation speed of 6 rpm.

  For the nozzle of the dispenser, 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 was brought into contact with a position 20 mm from the right end of the mold, and the supply of the resin was started. When the nozzle reached a position 20 mm from the left end of the mold, the supply of the resin was stopped, and 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, a tubular article of a predetermined length could be obtained, and a tubular article could be formed with almost no resin loss by simply cutting off both ends of about 2 mm to expose an end face. The variation in the thickness of the obtained tubular article was ± 1.0 μm, and the variation was small. The outer shape of the tubular article was measured with a roughness meter, and no undulations or irregularities were found. The appearance was good without any stripes.

[Example 1]
A tubular article was formed in the same manner as in Reference Example 1, except that 12 parts of potassium titanate whiskers (Tismo D, manufactured by Otsuka Chemical Co., Ltd.) were added as inorganic fillers instead of 10 parts of alumina powder manufactured by Showa Denko. The obtained tubular article had a circumferential strength of 25 kg / cm ² and an axial strength of 18 kg / mm ² , and was excellent in circumferential strength.

  The tubular article of the present invention can be used as a fixing belt of an electrophotographic copying machine, a facsimile, a printer, and the like.

It is explanatory drawing of the coating method using the dispenser of this invention. It is explanatory drawing of the shape of a nozzle tip in the coating method of this invention, and the contact position of a nozzle and a core.

Explanation of reference numerals

1: Dispenser,
2: Nozzle,
3: Liquid heat-resistant resin (spiral-coated)
4: Core.

Claims (2)

  A liquid heat-resistant resin containing a needle-like or flake-like inorganic filler is applied to the outer surface or inner surface of the core body which is a molding die, and the formed coating layer has a strength capable of maintaining at least the structure as a tubular material. Until the applied liquid heat-resistant resin is solidified or hardened, and then, in a method for manufacturing a tubular article including a step of taking out the tubular article from the core body, while rotating the core body, the outer surface or the inner surface of the core body has a thickness of 25%. A liquid heat-resistant resin having a viscosity at 100 ° C. of 100 to 15,000 poise is continuously supplied by a dispenser, and the center of the liquid discharge port of the dispenser supply section having the liquid discharge port is brought into contact with the outer surface or inner surface of the core body. By moving the supply portion of the dispenser in the rotation axis direction of the core body, the supplied liquid heat-resistant resin is spirally wound to form a coating layer. Method of manufacturing a tubing to symptoms.   A tubular article comprising a heat-resistant resin containing a needle-like or scale-like inorganic filler, wherein the strength in the circumferential direction is greater than the strength in the axial direction.

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