JPS6252301B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a toner image fixing device.

In fields that handle toner images such as electrophotography, it is used as a device to fix toner images on their supporting materials.
A device is often used in which a toner image support material is held and conveyed by a pair of rollers, at least one of which is heated from the inside or the outside, so that the toner is heated and melted and fixed on the support material. At that time, in order to prevent toner offset and the support material from wrapping around the roller, an anti-offset liquid (usually silicone oil is usually used) is applied to the fixing roller on the side of the support material that is in pressure contact with the toner image surface. It is well known to do so.

The methods currently in practical use for applying the above-mentioned anti-offset liquid to the fixing roller include directly contacting the fixing roller with felt that absorbs and retains silicone oil by capillary action, or by contacting the fixing roller with felt. This method supplies silicone oil to the fixing roller by bringing it into contact with a rotating coating roller or a roller in a row of coating rollers, but such a method tends to apply too much oil. As a result, the toner image support material becomes dirty with oil, and when ink is added to the support material later, the ink does not adhere well, and slips occur between the fixing and pressure rollers, disturbing the toner image. I do things. Even if this is not the case, the amount of oil consumed is uneconomical due to unnecessary waste, and maintenance is troublesome as the frequency of oil replenishment or oil supply cartridge replacement increases. Therefore, in US Pat. No. 3,718,116, US Pat. No. 3,745,972, and U.S. Pat. A device has been disclosed in which an attempt is made to reduce the amount of oil applied by bringing felt into contact with a roller. However, even with this device, the amount of coating is still large, and the amount of coating is more than necessary for preventing offset and preventing the support material from wrapping around the roller. And in the various devices mentioned above, it is 50 ~ at room temperature.
Although oil with a low viscosity of about 350CS can be applied relatively uniformly at first, it is difficult to swell when using a roller coated with silicone rubber.
It is useful because it is easy to handle during maintenance and inspection, and it is securely held without a large amount of liquid accumulating on the roller or dripping from the felt when the equipment is stopped. When using a viscous anti-offset liquid, the conventional method described above tends to cause streaks of uneven application, especially when using a device such as the one described in the above-mentioned publication in which a felt with dense fibers is brought into contact with a roller. It is extremely difficult to apply it evenly. Another serious drawback of the various devices described above, such as those in which anti-offset liquid is applied by bringing the felt into contact with a roller, is that carrier particles contained in the toner, paper dust, or latent image developer that forms the toner image. The above-mentioned felt is clogged, and this causes uneven coating. When this uneven coating occurs, toner offset occurs locally, and the image support material gets wrapped around the roller. Furthermore, if the fixing roller or pressure roller is coated with silicone rubber, the uneven coating results in a difference in the amount of swelling of the rollers, which is disadvantageous in that the toner image supporting material is more likely to wrinkle. Furthermore, if a large amount of toner adheres to the felt,
This damages the roller, further promotes the above-mentioned uneven coating, and further causes various fixing defects.

On the other hand, a silicone rubber roller with silicone oil infiltrated into the rubber structure or a roller coated with silicone rubber and a perforated pipe containing silicone oil is brought into contact with the fixing roller, and the anti-offset liquid is applied to the fixing roller through the rubber structure. Methods are also known. Although it is possible to uniformly apply a small amount using such a method, the amount is too small, and it is difficult to apply a single coat on A4 paper, like the fixing device used in current copying machines.
It is completely unsuitable for an apparatus that must fix seven or eight sheets or more per minute. In this method, the coating amount decreases further as the viscosity of the liquid increases.

Japanese Unexamined Patent Application Publication Nos. 52-110049 and 54-1988 provide a clue to solving the various inconveniences mentioned above.
There is a fixing device described in Japanese Patent No. 37752. The fixing device described in both of these publications uses a non-fibrous tetrafluoroethylene resin film with fine continuous pores, that is, it is made of a non-fibrous tetrafluoroethylene resin film that has fibers entwined with it like felt, or has air bubbles or single cells inside the film like a sponge. It is configured to control the amount of silicone oil applied to the fixing roller by using a polytetrafluoroethylene resin film that does not have a large amount of silicone oil dispersed in it, but has many fine holes that penetrate from the surface to the back of the film. ing. As a membranous body
GORE−TEX JOINT SEA−LANT (WL
GORE & ASSOCIAT-ES, INC. (trade name) and Fluoropore (Sumitomo Electric Industries, Ltd., trade name). The characteristics of such a membranous body are that continuous pores with extremely small diameters can be easily obtained, and the diameters of the pores are very uniform, and the diameter distribution is extremely narrow around the average diameter. The reason is that it is almost 100% concentrated in a small area and has a delta function shape. In any case, by controlling the amount of anti-offset liquid applied by bringing it into surface contact with such a membrane roller, it is possible to uniformly apply an appropriate amount of both low-viscosity and high-viscosity liquid to the fixing roller. . For example, the viscosity is similar to that of starch syrup, making it impossible to uniformly apply an appropriate amount using the aforementioned felt or silicone rubber devices.
Even 10000CS silicone oil can be applied evenly in an appropriate amount. Conversely, a small amount of silicone oil of about 50CS can also be applied. Moreover, the diameter of the aforementioned fine continuous pores is very uniform and is much smaller than the diameter of toner or paper powder, and the tetrafluoroethylene resin itself has a small surface energy.
No clogging caused by toner or paper dust,
Moreover, there is no possibility that toner will accumulate and stick to the film and damage the roller, and uniform application can be maintained for an extremely long period of time. However, it is a similar film. Since a thin material with a thickness of 0.05 to 1 mm is used, it must be held securely. Otherwise, deformation will proceed from the portion where the holding is not secure, resulting in uneven coating, overcoating, and even damage to the film. Therefore, the present invention aims to prevent the above-mentioned disadvantages by reliably supporting the above-mentioned membrane.

Here, in the fixing device of the present invention, an anti-offset liquid is applied to at least one of a pair of rollers that pinch and convey a supporting material in order to fix a toner image, through a tetrafluoroethylene resin film having fine continuous pores. In the fixing device, the tetrafluoroethylene resin film has a bag-like portion, and the bag-like portion is inserted into an opening formed in a support member that supports the tetrafluoroethylene resin film and hangs down. The present invention is characterized in that the tetrafluoroethylene resin film is supported by the support member by heat-sealing the tetrafluoroethylene resin film around the opening of the support member.

The present invention will be explained below based on embodiments shown in the accompanying drawings.

In FIG. 1, a fusing device 1 includes a pair of fusing rollers 2, 3 each having a layer of anti-offset material on its circumferential surface. The upper fixing roller 2 has, for example, a Teflon layer on its circumferential surface, and the lower fixing roller 3
is equipped with a silicone rubber layer. rollers 2, 3
are rotated in the directions of the arrows, thereby pinching and conveying the toner image supporting paper. At this time, the toner image is melted by the heat (usually 150 to 200 degrees Celsius) of the circumferential surface of the roller 2 heated by the heater 4. and is fixed on the supporting paper.

Reference numeral A designates a simple anti-offset liquid supply device according to the present invention, which is located above the upper fixing roller 2 to which the image surface side of the toner image supporting paper is pressed, and is swingably mounted around a shaft 10. It is elastically pressed against the roller 2 by a spring 11.

To explain in detail, the device A includes a box body 8. At the bottom of this box body 8, as shown in FIG.
A slit-like opening 8a is formed. The bag-shaped portion 5a of the oil control membrane 5 is inserted into this opening 8a and suspended outside the box.

That is, 5 is the aforementioned fluoropore or GORE-
A bag portion 5a having a U-shaped cross section is made of a polytetrafluoroethylene resin film having fine continuous pores, such as TEX JOINT SEALANT, and is drawn using a hot press. Peripheral portion 5b of this membrane 5 that is not formed in the bag
Then, the portion of the bag-shaped portion 5a that contacts the inner surface of the box 8 at the inner opening 8a is joined to the inner surface of the box 8, and this joining is performed as follows. i.e. box 8
As shown in FIG. 3, a thin layer 12 of polytetrafluoroethylene resin is baked onto the inner surface area in contact with the membrane 5.
The membrane 5 is brought into contact with this coating layer 12 at a temperature slightly lower (for example, approximately 300 degrees Celsius) than the melting point of the tetrafluoroethylene resin (approximately 320 degrees Celsius) in order to prevent the collapse of micropores and the deformation of the membrane.
Heat and pressurize to join. Instead of the above-mentioned 4-fluoroethylene resin layer, a thin 4-fluoroethylene-6-fluoropropylene copolymer resin layer is formed on the inner surface of the box body 8 by baking coating, and the membrane 5 is brought into contact with this layer surface. The membrane 5 may be joined to the box 8 by applying heat and pressure. Alternatively, as shown in FIG. 4, the above-mentioned box 8 is coated with a thin polytetrafluoroethylene resin layer 12, the above-mentioned copolymer resin thin layer 13 is further formed, and the film 5 is applied thereon.
By contacting and heating and pressurizing the membrane 5 to the box 8
It may be joined to. In the case of the latter two, the melting point of the copolymer is approximately 260°C, which is lower than that of the tetrafluoroethylene resin, so by setting the heating temperature between the two melting points, the membrane 5 will not melt, but the above-mentioned The copolymer melts and this makes the membrane 5 very strong.
Can be joined to.

The box 8 may be made of metal such as aluminum or brass, or may also be made of heat-resistant synthetic resin.
It is also possible to construct the box 8 from tetrafluoroethylene resin itself. In this case, it is of course not necessary to further coat the box with the tetrafluoroethylene resin layer as described above.
The membrane 5 may be thermally bonded to the tetrafluoroethylene resin box 8 directly or via the copolymer layer.

Now, the box 8 houses an elastic oil retaining member impregnated with silicone oil, such as a heat-resistant sponge or a heat-resistant felt 6, which is stuffed into the bag-shaped portion 5a of the membrane 5. The box 8 is attached to a support member 9 supported on a shaft 10. The spring 11 causes the lower surface of the membrane 5 stuffed with the felt 6 to come into contact with the roller 2. As mentioned above, the membrane 5 has continuous pores with an average pore size of 0.1μ to 5μ, and the silicone oil impregnated in the heat-resistant felt 6 is
It passes through these pores and is applied to the surface of the fixing roller 2. At this time, the membrane 5 is subjected to frictional force due to the rotation of the roller 2, but as described above, the membrane 5 is strongly supported by heat-sealing to the fluororesin surface of the box 8.
Although it is very thin and has poor mechanical strength, it can effectively prevent deformation, etc., and the roller 2 can be coated with an appropriate amount of oil evenly.

In the illustrated example, the bottom plate of the box body 8 is slightly protruded outward at the opening 8a, and the bag 5a is placed on the inner surface of the protrusion.
A part of it was joined. This reduces the area of the membrane 5 exposed to the outside air, reduces the amount of oil seeping out, reduces the amount of oil used, and maintains the shape and position of the bag portion 5a that comes into contact with the roller 2 at a constant level. This stabilizes the amount of oil applied.

Further, in the illustrated example, the surface of the film 5, on which the heat-resistant felt 6 holding the anti-offset liquid was brought into contact with the back surface, was brought into direct contact with the fixing roller 2. However, membrane 5
The surface is not fixed directly by the fixing roller 2, but by the fixing roller 2.
The roller of the roller-type anti-offset liquid supply means may be brought into contact with the roller of the roller-type anti-offset liquid supply means, such as a supply roller that rotates in contact with the supply roller, or another supply roller that rotates in contact with this supply roller.

In addition, Fluoropore and GORE-TEX JOINT SE
A tetrafluoroethylene resin film such as -ALANT, which has fine continuous pores, may have a property of being mechanically more easily stretched in one direction than in another direction. In this case, the polymers that make up the aforementioned membrane are oriented in a direction that is difficult to stretch, and therefore the membrane is difficult to stretch in this direction, but it is easy to stretch in the direction perpendicular to this direction. Put it away. The reason why the molecular directions are aligned in one direction is because the mass of the polymeric synthetic resin material is stretched during the production of the above-mentioned membrane. The molecules are aligned in this stretching direction, and the film has stretching resistance in this direction. For this reason, the direction in which the polymer synthetic resin film is difficult to stretch is herein referred to as the stretching direction, and the direction perpendicular to it, in which it is easy to stretch, is referred to as the non-stretching direction. This is for convenience, and it is important to note that the polymer synthetic resin membrane having continuous pores as described above may have a direction in which it is mechanically easy to stretch and a direction in which it is difficult to stretch mechanically. (For example, in the case of the film with the above trade name, it stretches 3 to 10 times in the non-stretching direction than in the stretching direction for the same force.) In any case, as mentioned above, the tetrafluoride film has an easy-to-stretch direction and a difficult-to-stretch direction. Ethylene resin film 5
When the membrane 5 is brought into contact with the roller with the rotational direction of the roller and the direction in which it is easy to stretch aligned, the membrane 5 will expand in the direction in which the roller 5 rotates due to the frictional force between it and the roller. Too much oil is applied to the roller. In particular, as in the device shown in Figure 1, the membrane 5 is 150 to 200.
When heated to temperatures as high as °C, it will stretch beyond its elastic deformation limit and not only will it not return to its original shape even when the rollers are stopped, but it may even break.
If the tetrafluoroethylene resin membrane 5 used therein has a direction in which it is easy to stretch and a direction in which it is difficult to stretch, this direction in which it is difficult to stretch at the contact portion between the roller and the membrane 5 coincides with the direction of rotation of the roller, and It is preferable to orient the membrane 5 so that the direction in which it is easy to stretch coincides with the generatrix direction of the roller, and then heat-seal and bond it to the box 8 as described above. Alternatively, if you use a laminated film in which two or more films are joined by heating and pressurizing, and the directions in which at least two films are difficult to stretch are crossed (orthogonally is preferable), each film in the laminated film will be The membrane may be oriented and heat-sealed to the box 8 in any manner. However, even in this case, it is also possible to heat-seal the film to the box 8 so that the direction in which at least one film in the laminated film is difficult to stretch matches the rotational direction of the roller at the contact area between the laminated film and the roller. It is.

The diameter of the continuous pores of the membrane-like body 5 used in the above apparatus, the porosity, the thickness of the membrane, and the viscosity of the offset prevention liquid are as follows: These various conditions that determine the toner are determined by the viscosity of the toner when it is melted, the stiffness of the toner image supporting material, the surface tension of the fixing roller, and the like. Factors such as the minimum amount of offset prevention liquid required per unit area of the toner image support material and the fixing processing speed, that is, the rotation speed of the fixing roller, in order to prevent offset and prevent the toner image support material from wrapping around the fixing roller. It should be determined taking into account the following. However, in toner image fixing devices used in fields such as electrophotography and other electrostatic printing, generally a film-like material 5
The continuous pores have an average diameter of 0.1 to 5μ and a porosity of 20
The 95% film thickness may be 0.05 to 1 mm, and the viscosity of the offset prevention liquid can be selected from a wide range of 100 to 100,000 CS at room temperature. In order to increase the amount of coating, the viscosity of the offset prevention liquid should be low, and/or the average diameter of continuous pores in the membrane 5 should be increased.
The porosity and/or the film thickness may be increased and/or the film thickness may be reduced, and the amount of coating may be reduced by reversing the above.

Further, in the above embodiment, the anti-offset liquid was directly supplied to the upper fixing roller 2 by the coating device having the film 5, but the coating device first applied the anti-offset liquid to the lower roller 3, and then the anti-offset liquid was applied from the lower roller 3. The same liquid may be supplied to the upper fixing roller 2.

Furthermore, although the above embodiments have shown an apparatus that heats and melts the toner to fix it, the present invention uses a pair of rollers to strongly clamp and convey the toner image supporting material, and the toner image is transferred onto the supporting material by the pressure. It can also be used in pressure fixing devices.

In any case, according to the present invention, a control membrane that does not get clogged with toner or paper powder and can supply an appropriate amount of both high and low viscosity liquids, that is, a film having fine continuous pores, is provided.
Because the fluorinated ethylene resin film is supported by heat-sealing on the support, even though the film itself is very thin, it can easily prevent deformation of the film during roller rotation, etc. The anti-offset liquid can be evenly and uniformly applied to the fixing roller, and since the liquid can be prevented from seeping out on the heat-sealed surface, there is also the effect of preventing wastage of the anti-offset liquid.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an embodiment of the present invention, FIG. 2 is an exploded view of essential parts of the embodiment, and FIGS. 3 and 4 are enlarged views of a joint. 2 and 3 are fixing rollers, 5 is a tetrafluoroethylene resin film having fine continuous pores, 8 is a box, 12 is a tetrafluoroethylene resin coating layer, and 13 is a tetrafluoroethylene-6
This is a fluorinated propylene copolymer layer.

Claims (1)

[Scope of Claims] 1. An anti-offset liquid is applied to at least one of a pair of rollers that grip and convey a supporting material in order to fix a toner image through a tetrafluoroethylene resin film having fine continuous pores. In the fixing device, the tetrafluoroethylene resin film has a bag-shaped portion, and the bag-like portion is inserted into an opening formed in a support member that supports the tetrafluoroethylene resin film and is allowed to hang down. . A fixing device, characterized in that the tetrafluoroethylene resin film is supported by the support member by heat-sealing the tetrafluoroethylene resin film to a portion around the opening of the support member. 2. The fixing device according to claim 1, wherein the supporting member has a fluororesin surface, and the tetrafluoroethylene resin film is heat-sealed to the fluororesin surface. 3. The fixing device according to claim 2, wherein the fluororesin surface is constructed by baking-coating a tetrafluoroethylene resin onto a supporting member base. 4. The tetrafluoroethylene resin film having fine continuous pores is formed through the tetrafluoroethylene-hexafluoropropylene copolymer resin layer, and has a melting point higher than that of the copolymer resin and higher than the melting point of the tetrafluoroethylene resin. 4. The fixing device according to claim 1, wherein the fixing device is heat-sealed to the support member at a low temperature.