JPS60186883A - Roller fixing device - Google Patents

Abstract

PURPOSE:To shorten the temperature rising time of a heat roller and prevent occurrence of offset phenomena, by forming the covering layer of at least one roller out of plural fixing rollers with a non-tacky porous material having continuous pores and eliminating the pores from the surface of the covering layer. CONSTITUTION:A heat roller 10 equipped with a covering layer 14 is formed by providing a heat source 12 inside the main body 11 of the roller made of copper, aluminium, etc., and winding a non-tacky porous plastic film having continuous pores around and outer peripheral surface of the main body 11. Moreover, a pressing roller 16 is formed in such a way that an elastic material 18 made of silicone rubber, etc., is fitted to the outer peripheral surface of the main body 17 of the roller 16 as a buffer layer and the non-tacky porous plastic film having continuous pores is wound around the outer peripheral surface of the buffer layer so as to form a covering layer 20. The covering layers 14 and 16 are pressed against a hard roll so as to eliminate pores from the surface. A copying paper (not shown in the figure) is passed through between the heat roller 10 and pressing roller 16 and a toner image is fixed. Therefore, the temperature rising time of the heat roller 10 is shortened and occurrence of offset phenomena is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a roller fixing device for an electronic copying machine, and particularly to a roller fixing device for an electronic copying machine, which prevents the occurrence of an offset phenomenon due to the transfer of a toner image to a heated fixing roller of an electronic copying machine, and also prevents the occurrence of an offset phenomenon due to the transfer of a toner image to a heating roller of an electronic copying machine. This enables efficient fixing by shortening the time, and furthermore, the toner image after fixing has no gloss, making it possible to make clear copies.

In general, electronic copying machines for the purpose of dry copying:
A method is adopted in which the toner image formed on copy paper by electrostatic electricity or magnetism is fixed by passing the copy paper between two rotating rollers that are in pressure contact with each other and heating one or both of the rollers from within. has been done.

Compared to other open fixing methods, this method of fusing has many advantages such as easy speedup and high thermal efficiency. However, since the toner image on the copy paper is pressed against the circumferential surface of the heating roller in a heated and molten state, part of the toner image adheres to the circumferential surface of the roller and is transferred. Alternatively, this toner image is further transferred to the other roller, and this image is retransferred and appears on the next copy paper, which is a so-called offset phenomenon, which may stain the copy paper.

Therefore, in order to prevent such adhesion of toner images, heating and/or pressure rollers made of metals such as stainless steel and aluminum are coated with materials that have excellent releasability for toner images on their surfaces. For example, tetrafluoroethylene resin (P
A non-adhesive thin film made of fluororesin such as TFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), or silicone resin is applied directly to the metal roller or as a buffer layer on a rubber-like material such as synthetic rubber. It is coated after being previously coated with a material that exhibits elasticity.

Conventionally, methods for forming these non-adhesive thin films on the roller surface include preparing a heat-shrinkable tube made of the above-mentioned resin, placing the heat-shrinkable tube over the roller, and covering the roller by heat-shrinking it, or coating the roller with the above-mentioned resin. A method has been adopted in which a dispersion, solution, or powder is applied to a roller, baked, and then the surface is polished to form a non-adhesive thin film.

However, when a thin film is formed to prevent offset using this method, there are problems such as poor thermal conductivity of the heating roller, poor stability of the roller surface temperature, or problems with the non-adhesive surface. However, there were disadvantages in that the fixing roller was not sufficient as a fixing roller, the copies were glossy and difficult to see, and clear copies could not be made.

In other words, in the method using heat-shrinkable tubes, there is a limit to the thickness of the heat-shrinkable tube due to manufacturing reasons, making it difficult to reduce the thickness of the tube.As a result, the heat conductivity of the heating roller deteriorates, and it takes time for the temperature of the roller surface to rise, making startup difficult. The problem is that it's slow.

Furthermore, if the surface hardness of the fixing roller (heating, pressure, or both rollers) is hard, the molten toner tends to be crushed more than necessary when pressure is applied, and as a result, the toner image becomes glossy and difficult to see. In even worse cases, the outline of the toner image may become blurred. For this reason, an elastic material such as silicone rubber is provided as a buffer layer between the metal roller and the heat-shrinkable tube, but even with this structure, the thickness of the heat-shrinkable tube is large, so the buffer layer is The effect of the layer is not fully demonstrated, and there is still room for improvement.

In addition, if the resin is applied to a roller in the form of a dispersion, solution, or powder and a non-adhesive thin film is formed by baking, etc., the inherent non-adhesive properties of the resin will be significantly reduced, so that There is a problem with the mold releasability, and the durability is not sufficient as a fixing roller.

This invention was made in view of the above-mentioned shortcomings of the prior art, and it does not cause any offset phenomenon even when used for a long period of time in an electronic copying machine. To provide an inexpensive roller fixing device which saves time, produces copies without gloss, is clear, and has excellent durability.

Therefore, according to the present invention, a plurality of rollers are provided in pressure contact with adjacent rollers, a coating layer for fixing is provided on the outer surface of at least one of the rollers, and copy paper holding a toner image is placed between the plurality of rollers. In a roller fixing device for fixing a toner image onto the copy paper by passing the coating layer through the sheet, the coating layer is covered with a continuous porous material made of non-adhesive plastic, and at least the surface portion thereof is made of a non-porous material. As a result, the toner image is not pressurized more than necessary, and the toner image is not glossy. Clear copying becomes possible.

The present invention will be explained in more detail below with reference to the attached drawings, but of course the present invention is not limited to the embodiments. Various modifications and combinations within the technical idea of the present invention are possible, such as providing the pressure roller with a non-adhesive coating layer or coating only one pressure roller with a non-adhesive coating layer.

The roller fixing device according to the present invention includes a heat source 12 such as a quartz tube heater inside a roller body 11 made of copper, aluminum, etc., as shown in FIG. A heating roller 1 having a coating layer 14 formed by winding a continuous porous plastic film.
0, an elastic material 18 made of silicone rubber or the like is adhered as a buffer layer to the outer peripheral surface of a metal roller body 17, and a non-adhesive open-cell porous plastic film is further wrapped around the outer peripheral surface. The pressure roller 16 having the coating layer 20 is supported in a state in which they are in pressure contact with each other, and is rotationally driven by a motor (not shown). The heating roller 10 is heated by a heat source 12 during operation of the fixing device, and the temperature is appropriately set depending on the type of toner used. In addition to forming the coating layer 14, 20, or both by wrapping a continuous porous plastic film, it is also possible to cover the coating layer 14, 20, or both with a plastic tube having a continuous porous structure. As shown in FIG. 2, these coating layers 14.2o are generally formed so that their surface portions 3o are non-porous, leaving a porous layer 31 inside. As a method for forming the porous material without pores, for example, after coating the porous material, a method such as rotating the porous material against a roll having a hard surface can be used.

Further, the coating layer may not only have its surface portion made non-porous, but also may be crushed entirely into a non-porous state by applying pressure.

The coating layer is formed by applying an adhesive to the outer circumferential surface of the roller main body and the elastic material 18, or by forming a heat-sealable plastic layer and wrapping the layer around it. .

A layer such as FEP can also be provided, and if necessary, the surface of the tape to be adhered may be surface-treated using a surface-treating agent, a corona discharge device, or the like.

In this case, the open-cell porous material is a plastic molded body having non-adhesiveness and heat resistance, such as tetrafluoroethylene resin (PTFE), tetrafluoroethylene-hexafluoride resin, etc. Propylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (
PFA), ethylene-tetrafluoroethylene copolymer, and other fluorocarbon resins are processed by known methods such as stretching, salt elution, solvent volatilization, and sintering to form a large number of fine continuous pores as an internal structure. Films or tubes having a porous microstructure can be used, but from the viewpoint of non-adhesiveness, heat resistance, etc., films or tubes made of stretched continuous porous polytetrafluoroethylene resin (E-PTFE) are preferred. be.

E-PTFE is manufactured by the method disclosed in Japanese Patent Publication No. 51-18991, for example, and is a porous material having a microstructure in which micronodules are connected to each other by a large number of fibrils, and the fibrils are separated from each other by holes. In addition, it is possible to have both high porosity (40 to 99%) and high strength (matrix tensile strength 514 Kg/crn" or more), and it also has excellent flexibility. This makes it the most suitable coating layer.The pore diameter is 0.05.
Preferably, the thickness is between 10 μm and 10 μm.

Due to its continuous porous structure, the open-cell porous plastic molded article used in the present invention can be arbitrarily molded to have no pores on its surface or its entire surface by means such as pressurization.

Therefore, a coating layer that is made non-porous by applying pressure or the like after coating these porous materials has a lower toner releasability than a coating layer made of a conventional solid plastic tube. It is not inferior. Moreover, if only the surface of the coating layer is made non-porous and a porous structure is left inside, the pores will act as a buffer layer and increase the elasticity of the coating layer, preventing too much pressure on the toner image and providing gloss. Clear copies can be made without any blemishes.

However, even when the continuous porous material forming the coating layer is pressurized to make the entire coating layer non-porous, the porous material has a small coefficient of friction and the microfibers are fine fibers that can be freely displaced. Since it is made of porous flesh, it has more elasticity than the conventional plastic covering layer with a solid structure, and does not pressurize the toner image more than necessary. Furthermore, in this case, the coating layer is crushed and its thickness becomes thinner, which has the effect of improving thermal conductivity.

Next, examples of the present invention will be described.

Example 1 A silicone thermosetting adhesive was applied to the surface of a 45 mm diameter aluminum roller with a built-in heater in the center.
Furthermore, an 80 μm thick E-PTFE film whose surface to be adhered had been surface-treated in advance was wound spirally thereon, and the film was pressed and shaped using a roll with a hard surface so that the surface portion was non-porous. The heating roller is manufactured by curing the adhesive in a heated atmosphere and forming a non-adhesive coating layer on the roller surface integrally with the roller body, while the surface of the aluminum roller is made of commercially available silicone rubber as a buffer layer. The pressure roller was coated to have a diameter of 45 mm, and a non-adhesive coating layer similar to that of the heating roller was formed on the outer peripheral surface of the pressure roller, and the roller fixing device shown in FIG. 1 was constructed using these rollers. In this case, the surface hardness of the pressure roller is Shore A.
When the temperature was 60 or less, the increase in hardness was 5 or less.

For comparison, a similar roller fixing device was constructed using a 3.5 mm thick heat shrink tube made of PTFE.

The surface hardness of the pressure roller was 85 or more in Shore A.

When these roller fixing devices were set in the fixing section of an electronic copying machine and the toner image was fixed on paper at a roller surface temperature of 180°C, and the occurrence of offset was observed, no offset was observed in either case. However, when the roller fixing device according to the present invention was used, it was possible to obtain a clear copy with less gloss than the conventional example.

In addition, when using a roller fixing device in which a coating layer made of a porous material is made almost non-porous by applying pressure, the porous structure collapses and the thickness of the coating layer becomes thinner. , improved thermal conductivity and reduced startup time. Furthermore, since the coating layer has low friction and is made of a fine fibrous porous flesh in which the microfibers can freely displace, it is difficult to achieve the conventional full-featured coating layer, especially when stretched open-cell porous PTFE is used. It was more elastic than the structural plastic coating layer, and it was possible to obtain clear copies.

In addition, when covering the outer peripheral surface of the heating roller with a continuous porous material, it is possible to coat the coating layer with a conductive continuous porous material containing a filler with good conductivity. It can be provided with conductivity.

As the conductive filler, metal powders such as copper, aluminum, and nickel, metal oxides, metal nitrides, or inorganic powders such as carbon black and graphite are suitable, and these fillers may be used alone, but 2 These types or more may be used in appropriate combinations, within a range that does not impair the releasability of the toner image of the coating layer made of a continuous porous material, preferably in an appropriate amount so as to be 10' to 10 gΩ·Cm. Added.

For example, carbon plastic is l wt% to l Qwt
It was suitable to mix within the range of %.

If the main body of the heating roller is made of metal, an insulating layer is provided between the metal roller and the conductive coating layer to provide electrical insulation, and electrical contacts are connected to both axial ends of the conductive coating layer. By energizing the coating layer itself, the coating layer itself can generate heat. (Not shown) In this case, the heat source inside the heating roller body and the heat source of the coating layer itself can be used together, but it can also be used by only energizing the coating layer without using the heat source inside the heating roller body. . In this case, it is also possible to form the heating roller main body from an electrically insulating material and omit the insulating layer between it and the covering layer.

However, since the conductive coating layer is both an electrical conductor and a thermal conductor, it is possible to form the conductive coating layer directly on the outer peripheral surface of the metal heating roller body and use only the heat source inside the heating roller body. In this case, the thermal conductivity of the coating layer is increased and the thermal efficiency of the heating roller is improved, compared to a conductive coating layer containing a conductive filler.

Note that the above conductive coating layer can be used not only for heating rollers, but also for heating rollers.
It can also be used as a covering layer for pressure lawns.

In this way, the surface of each roller is not charged when the heating roller and pressure roller rotate in pressure contact with each other, so there is no need for a paper peeling mechanism for peeling off the copy paper adsorbed to the surface of the roller. Foreign matter such as dust does not adhere to the surface of each roller, which simplifies maintenance and management.

Furthermore, in the case of forming a conductive coating layer, even if the electrical conductivity of the porous part is low (that is, even if the amount of conductive filler mixed in is small), the electrical conductivity of the surface part will decrease due to pressure and compression of the surface part. Since the amount increases, a static electricity removal effect can be imparted, and a heating effect can also be imparted by using the surface layer as a heater.

As explained above, according to the present invention, a plurality of rollers are provided which are in pressure contact with adjacent rollers, and at least one of the rollers is
A roller fixing device in which a coating layer for fixing is provided on the outer surface of a book roller, and the copy paper holding the toner image is passed between the plurality of rollers to fix the B toner image onto the copy paper. By covering the coating layer with a non-adhesive open-pore porous material and making at least the surface part non-porous, the elasticity of the coating layer is improved without reducing the non-adhesive property, and as a result, it can be used for a long time. Even when used for a period of time, no offset phenomenon occurs, and the toner image is not pressurized more than necessary, making it possible to obtain copies that are glossy, easy to see, and have clear outlines.

In addition, even when the entire surface of the coating layer is made non-porous, that is, crushed, the elasticity of the coating layer remains, resulting in better copies compared to those using plastic with a solid structure. At the same time, the thinning of the coating layer improves thermal conductivity, which shortens the time required to raise the temperature at the start of copying, resulting in energy savings.

Furthermore, by making the coating layer of the present invention a conductive coating layer, it is possible not only to improve the thermal conductivity of the coating layer and prevent static electricity, but also when the coating layer itself is used as a heat source for a heating roller. Because the conductive solid material in the coating layer has a self-adjusting function for surface temperature, there is no temperature unevenness, and the temperature rise time at the start of copying or temperature recovery time upon contact with copy paper is further shortened. This not only significantly improves thermal efficiency and significantly shortens the time required for copying, but also eliminates the internal heat source of the heating roller, meeting the demands for energy saving and rapid copying.
The roller fixing device is extremely suitable for use in electronic copying machines. In addition, when bonding the outer peripheral surface of the roller with a continuous porous material, fillers such as carbon black, TiO2 powder, BaTiO2 powder, etc. may be integrated with the material to improve adhesion. Various modifications and combinations within the present technical concept are possible, such as attaching a film mixed with a possible impurity to the material in advance using a method such as heat fusion.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a roller section showing an embodiment of the present invention, and FIG. 2 is a cross-sectional view of a fixing roller used in the present invention. lO: heating roller, ■4/20: coating layer, 16: pressure roller, 18: elastic material, 30: surface portion, 31: interior. Patent applicant Junko Co., Ltd. Company F; g, f Nomu

Claims (1)

[Scope of Claims] 1) A plurality of rollers are provided in pressure contact with adjacent rollers, a coating layer for fixing is provided on the outer surface of at least one of the rollers, and copy paper holding a toner image is provided on the outer surface of at least one of the rollers. "
In the roller fixing device that fixes the toner image on the copy paper by passing the toner image between J and R, the coating layer is made of a non-adhesive continuous porous material, and at least the surface thereof is made non-porous. A roller fixing device characterized by: 2. The roller fixing device according to claim 1, wherein the porous material is an open-cell porous plastic molded into a film or a tube shape. 3) The roller fixing device according to claim 1 or 2, wherein the porous material is a stretched continuous porous polytetrafluoroethylene resin. 4) A roller fixing device according to any one of claims 1 to 3, wherein the porous material contains a conductive filler.