JPH0872149A - Film bonding method and production of transfer belt of image forming apparatus - Google Patents

Abstract

PURPOSE: To obtain an extremely flat bonded part even in a wide thermoplastic resin film by superposing a meshlike jig on the bonded part wherein both end edges of a film are superposed one upon another and performing ultrasonic welding in such a state that the meshlike jig is interposed. CONSTITUTION: In an ultrasonic welding apparatus, at first, the end parts superposed one upon another of a film 21 are fixed to the meshlike jig 25 placed on a base stand 23 by a clip 24 and, next, the film 21 is held between the tip part of an ultrasonic horn 25 and the meshlike jig 25 at the position of the slitlike opening part 26 of the clip 24. When ultrasonic vibration is applied to the film while the end parts of the film are pressed, the film 21 is melted by ultrasonic energy to be bitten in the mesh parts of the jig to finally obtain uniform seamless endless transfer belt wherein meshlike treatment is applied to the film 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film joining method, and more particularly to a film joining method capable of obtaining an extremely flat joint even in the case of a wide thermoplastic resin film.

Further, the present invention relates to an endless transfer belt of an image forming apparatus obtained by such a joining method.

[0003]

2. Description of the Related Art Generally, since a thermoplastic resin film is melted by heat energy, it can be easily joined by applying heat energy in a pressed state. However,
In the case of a film having no heat-sealing property such as a polyethylene terephthalate film, the above method cannot satisfactorily bond the film. Therefore, a method of applying ultrasonic vibration to the bonding portion under a pressing force to bond the bonding portion is used.

A general device for joining by utilizing ultrasonic vibration is an ultrasonic oscillator, an ultrasonic horn fixed to the ultrasonic oscillator, and an ultrasonic horn disposed at a position facing the ultrasonic horn. And a device for applying a pressing force to the ultrasonic horn, and the like. The joint portion of the thermoplastic resin film is sandwiched between the ultrasonic horn and the base and is subjected to ultrasonic vibration under pressure, so that it can be easily welded even if it has no heat-sealing property (heat-sealing property). it can.

[0005]

Such joining of thermoplastic resin films by ultrasonic waves can generally be carried out by the method shown in FIG. In this case, both ends of the thermoplastic resin film 12 are superposed, sandwiched between the ultrasonic horn 13 and the base 14, and ultrasonically welded under pressure. According to this method, the both end portions of the film appear to be strongly bonded, but in reality, only the contact surfaces 15 thereof are welded, and therefore, when a diagonal force or a twisting force is applied, they easily peel off. There is a problem that it will end up. Moreover, due to the overlapping, the joint portion becomes thick, and the flatness of the joined film is poor.

As described above, the film joining method as shown in FIG. 3 has the drawbacks that the welding strength and joining accuracy are not satisfactory, and the film joining portion is not flat.

[0007] The drawbacks associated with such a film joint are fatal problems particularly in a transfer belt used in an image forming apparatus.

As one type of color image forming apparatus of the color separation image superposition transfer system, toner images of different colors are formed on a plurality of photoconductors, and one sheet is conveyed in contact with each photoconductor in sequence. There is one in which the toner image on each photoconductor is transferred by aligning the position with the transfer material to obtain a full-color image.

FIG. 4 is a view showing the schematic arrangement of an example of this type of color image forming apparatus.

The image forming apparatus shown in FIG. 4 has photosensitive drums 1a to 1d around which primary chargers 2a to 2d are provided.
d, exposing means 3a to 3d, developing devices 4a to 4d, transfer charging devices 5a to 5d, discharging and discharging devices 6a to 6d and 7a to 7d,
The photosensitive drum cleaning devices 8a to 8d are arranged,
Further, an endless belt-shaped transfer belt 11 is arranged below the photosensitive drum so as to penetrate these units,
A transfer belt cleaning device 10 having a urethane blade 9 is arranged.

The transfer material P'is fed by a paper feed roller and then conveyed by an endless belt-shaped transfer belt 11 through a transfer section in which the transfer dischargers 5a to 5d are arranged.

By the way, as the transfer belt 11, generally, an endless belt is used by superposing both ends of a sheet-like dielectric film and joining them by ultrasonic fusion. Since a dielectric film having a thickness of about 30 to 500 μm is used for the transfer belt, as shown in FIG.
A step 17 and a protruding portion 18 having substantially the same thickness are formed.

Therefore, the above-mentioned cleaning device 10
When the transfer belt 11 is cleaned with, since the cleaning cannot be sufficiently performed at the step portion, the toner remains on the step portion. Therefore, when the transfer material is subsequently placed on the transfer material, a clear black stripe-like back stain occurs on the back surface of the transfer material.

Further, the stepped portion or the protruding portion of the joining portion of the transfer belt may come into contact with the cleaning blade as shown in FIG. 5 or run on the driving roller as shown in FIG. 6 during long-term use. There was a problem in that it was damaged and peeled off near the joint.

In order to solve such a problem, Japanese Patent Laid-Open No.
No. 8-193113 and JP-A No. 58-193114 have been proposed, but these methods require a buffer layer or have voids in the joint, so that sufficient joint strength cannot be obtained. It had a drawback.

Therefore, it is an object of the present invention to provide a method for joining thermoplastic resin films capable of providing a joint having sufficient welding strength and precision and good flatness.

Another object of the present invention is to solve the above problems of the conventional transfer belt having a seam, and to provide a method for producing a seamless transfer belt having an excellent durability.

[0018]

Means for Solving the Problems As a result of earnest research to achieve the above-mentioned object, the present inventor has found that ultrasonic waves are applied to a joint portion where both end edges of a thermoplastic resin film are overlapped with each other through a mesh jig. It has been found that by performing fusion bonding, it is possible to obtain a bonded portion having sufficient welding strength and good flatness with extremely high precision, and completed the present invention.

According to the present invention, a mesh jig is superposed on a joint portion where both edges of the film are superposed, and ultrasonic fusion is performed with the mesh jig interposed. A method of joining films is provided.

That is, the joining method of the present invention is characterized in that ultrasonic welding is performed in a state where a mesh-shaped jig is interposed in the joining portion where both end edges of the film are overlapped.

Further, according to the present invention, ultrasonic fusion is performed on a joint portion where both end edges of the film are overlapped with each other through a mesh jig, and an endless transfer used in an image forming apparatus. A method of manufacturing a belt is provided.

The joint portion of the endless belt thus obtained has a very good flatness and takes the form of a substantially completely seamless endless belt.

As an example of the mesh used in the present invention, a material having an arbitrary structure can be used as long as it has mesh-like irregularities on the surface. If a material having flexibility and elasticity, such as cloth, net or rope, is used, the joint has a certain degree of freedom at the time of fusion, so that the joint is uniformly crushed and voids are generated in the joint. Can be suppressed. The array direction of the mesh shape is
It may cross in one direction or in two directions. Furthermore, the mesh shape is not limited to a quadrangle, and may be a polygonal shape or an elliptical shape.

Further, the size of the mesh jig can be appropriately determined according to the thickness of the film and the size of the overlapping portions of both end edges of the film, and the width thereof is the joining portion of the films to be joined. It is desirable to be wider than the width of.

[0025]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIGS. 1 and 2 show a state in which both ends of a film are bonded by ultrasonic welding according to the present invention to manufacture an endless transfer belt.

In FIGS. 1 and 2, an apparatus for ultrasonically bonding a film 21 includes an ultrasonic horn 22 fixed to an ultrasonic oscillator (not shown), a base 23 for mounting the film 21, and a base 23. And a mesh jig 25 positioned so as to contact the film on the lower surface, and a clip 24 for fixing the film 21 on the base 23.

The clip 24 has a slit-shaped opening 26, and in this opening 26, the film 21 is formed.
Are sandwiched between the ultrasonic horn 22 and the mesh jig 25.

In such an ultrasonic welding device 27, the film 21 is clipped on the mesh jig 25 placed on the base 23 with the end portions of the film 21 first superposed.
Fixed by. Next, at the position of the slit-shaped opening 26 of the clip 24, the film 21 is attached to the ultrasonic horn 2.
It is sandwiched between the tip of 2 and the mesh jig 25. When ultrasonic vibration is applied while pressing in this state, the film 21 is melted by ultrasonic energy, the mesh part digs in, and the film 21 is finally subjected to a mesh-like treatment, which is uniform and seamless endless. A belt-shaped transfer belt is obtained.

In the present invention, the mesh processing is
The method is not limited to the above-mentioned method, and may be performed on the upper surface or both surfaces of the film.

The pressing force and ultrasonic energy required for welding depend on the film side conditions such as film material and thickness,
Jig conditions such as the material and thickness of the mesh jig used, as well as welding conditions such as fusing speed, are taken into consideration. Such conditions should be tested by a simple test. Can be easily found.

In this embodiment, FIGS. 1 and 2 are used.
As shown in FIG. 3, the base 23 is fixed and the ultrasonic horn 22 moves.
2 may be fixed and the base 23 may move.

Further, in the present embodiment, the tip of the ultrasonic horn 22 is a tapered pencil type, but it has a long shape in the width direction of the film and a wide horn shape that covers the entire width of the film. Some are preferred. The wide horn allows flattening at a time, and uniform pressing improves flatness.

The joints of the endless belt obtained in this way have a very good flatness and therefore have the form of an almost completely seamless endless belt, and thus of the conventional construction shown, for example, in FIG. When it is used as the transfer belt 11 of the image forming apparatus, it is not damaged by coming into contact with the cleaning blade or riding on the driving roller, and the problem of peeling in the vicinity of the joint does not occur.

The present invention can be applied to all thermoplastic resin films, but is particularly suitable for thermoplastic resin films in which heat fusion is difficult. As such a thermoplastic resin film, polyesters, polyvinylidene fluoride,
Examples include PEEK (polyether ether ketone). Needless to say, the joining method of the present invention can be applied to polyethylene or polyvinyl chloride that can be heat-sealed. The polyesters are generally thermoplastic resins composed of saturated dicarboxylic acid and saturated dihydric alcohol,
Examples thereof include polyethylene terephthalate, polypropylene terephthalate, polytetramethylene terephthalate (polybutylene terephthalate), polyhexamethylene terephthalate, polycyclohexane-1,4-dimethylol terephthalate, polyneopentyl terephthalate, polyethylene naphthalate and polycarbonate. Of these, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and polycarbonate are particularly preferable.

These thermoplastic resin films have high strength,
In order to improve dimensional stability, heat resistance, etc., it is preferable to use a biaxially stretched material.

Further, the thermoplastic resin film used in the present invention contains a heat stabilizer, a light stabilizer, a heat stabilizer, a light stabilizer, and the like for the purpose of improving a filler such as an inorganic filler and carbon black, and other physical properties and chemical properties. A flame retardant, a plasticizer, an antistatic agent, etc. can be added as appropriate. Further, the thickness of the film to which the method of the present invention is preferably applied is 1 to 100.
It is about 0 μm, and a film of about 30 to 500 μm is particularly preferable. The film width (corresponding to the length of the joint portion) is not particularly limited. The diameter of the endless film is also not limited, and it can be widely produced from 5 cm or less to several m or more.

[0038]

As described above, according to the film bonding method of the present invention, since ultrasonic fusion is performed through a mesh-shaped member, the bonded portion obtained is not only strong but substantially A flat, seamless endless film can be produced.

The endless transfer belt obtained by such a joining method has a good cleaning property at the joining portion, prevents the rear surface of the transfer material from being soiled, and is excellent in durability.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing a film joining method according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of the main part of FIG.

FIG. 3 is an explanatory view showing a conventional film joining method.

FIG. 4 is a sectional view showing an overall schematic configuration of a normal image forming apparatus provided with a transfer belt.

FIG. 5 is an explanatory view showing a relationship between a transfer belt and a cleaning blade obtained by a conventional joining method.

FIG. 6 is an explanatory diagram showing a relationship between a transfer belt and a driving roller obtained by a conventional joining method.

[Explanation of symbols]

 11 Transfer Belt 20 Drive Roller 21 Film 22 Ultrasonic Horn 23 Base Stand 24 Clip 25 Mesh Jig 26 Opening 27 Ultrasonic Fusing Device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsumi Aoki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Etsukaku Sakakibara 3-30-2 Shimomaruko, Ota-ku, Tokyo Non-Inside Co., Ltd. (72) Inventor Katsuhiko Otani No.402, Asakusabashi Heights No. 402, Asakusabashi, 5-2-14, Asakusabashi, Taito-ku, Tokyo

Claims (11)

[Claims] 1. A method for joining films, characterized in that a mesh jig is placed on a joining portion where both edges of the film are overlapped, and ultrasonic fusion is performed with the mesh jig interposed. . 2. The method for joining films according to claim 1, wherein the film is polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, or polycarbonate. 3. The film joining method according to claim 1, wherein the mesh jig is in the form of cloth, net or rope. 4. The mesh jig according to claim 1, wherein the mesh jig is interposed between a base of an ultrasonic welding device and a joint portion of the film. How to join films. 5. The width of the mesh jig is wider than the width of the joint portion of the film.
4. The method for joining films according to any one of 4 above. 6. A method for manufacturing an endless transfer belt of an image forming apparatus, wherein ultrasonic fusion is performed on a joint portion where both edges of the film are overlapped with each other through a mesh jig. 7. The method for producing an endless transfer belt according to claim 6, wherein the film is polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, or polycarbonate. 8. The method for joining films according to claim 6, wherein the mesh jig is in the form of cloth, net or rope. 9. The mesh jig according to claim 6, wherein the mesh jig is interposed between a base of the ultrasonic welding device and a joint portion of the film. How to join films. 10. The width of the mesh-shaped jig is wider than the width of the joint portion of the film.
10. The method for joining films according to any one of 9 to 9. 11. An image forming apparatus comprising an endless transfer belt manufactured by the method according to claim 6.