JPS641031B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a roller-type fixing device, particularly in a fixing device configured to apply an anti-offset liquid to a fixing roller.

As a roller type fixing device, there is a pressure fixing device that fixes the toner image on the supporting material by the pressure when the toner image supporting material is conveyed under pressure by a fixing roller, and a pressure fixing device that fixes the toner image on the supporting material by applying pressure when the toner image supporting material is conveyed under pressure by a fixing roller, and There is a heat fixing device that uses rollers to convey the toner image under pressure, and heats the toner image to melt it and fix it on the supporting material.

In any case, in order to prevent toner offset, an anti-offset liquid such as silicone oil is applied to the fixing roller.

At this time, if the amount of coating liquid is large, it will stain the toner image support material, and conversely, if the amount of coating liquid is small, the surface of the fixing roller is smooth and has poor wettability, and the entire circumferential surface cannot be uniformly wetted. A partial offset occurs. However, if it can be applied evenly and evenly, offset can be prevented with a very small amount of liquid.

Therefore, the main purpose of the present invention is to solve such inconveniences. Therefore, the fixing device of the present invention includes:
In a fixing device that fixes an unfixed toner image by passing a supporting material that supports the unfixed toner image between a pair of rollers, the roller on the side that comes into contact with the unfixed toner image is coated with an anti-offset liquid and a surfactant. It is characterized by the fact that an agent is applied.

Embodiments of the present invention will be described below with reference to the drawings.

The figure shows a pressure fixing device according to an embodiment of the present invention.

In the figure, 1 and 2 are hard chrome-plated fixing rollers, which are brought into pressure contact by applying a high load to both ends.
At this time, the fixing roller 1 and the fixing roller 2 are arranged so that their axes are slightly inclined to each other so that the pressure distribution in the axial direction is uniform. The roller 2 is rotationally driven in the direction of the arrow by a motor (not shown), and the roller 1 is driven to rotate in the direction of the arrow by frictional force.

3 is an entrance guide, 4 and 5 are separating gourds, and 6 and 7 are cleaning members for scraping the developer offset on the surface of the fixing roller. The image support material S (paper, plastic sheet such as an OHP sheet, etc.) supporting the unfixed toner image T is guided by the guide plate 31 and enters the pressure contact portion of the rollers 1 and 2, and is conveyed under pressure by the rollers 1 and 2. The toner image is then fixed to the support S only by pressure. If the supporting material S remains in close contact with one of the rollers when it comes out from the pressure contact portion of the pair of rollers 1 and 2, the supporting material S is peeled off from the roller by the melon 4 or 5. In order to fix the toner image by pressure, the pair of rollers 1 and 2 is pressed with a strong pressure of 10 to 60 kg per 1 cm in the axial direction. Since such strong pressure is applied, rigid rolls made of steel or the like are used as the base for rollers 1 and 2, and the surfaces of the rollers must have durability, hardness, low friction, and good mold release properties. For this reason, the rigid roll is usually formed by applying smooth hard chrome plating to the circumferential surface of the rigid roll.

Even if the surface of the fixing roller is formed of hard chrome plating or the like with good releasability, toner offset is inevitable, and the offset toner not only increases the burden on the cleaning members 6 and 7, but also damages the members. The toner that was not removed in steps 6 and 7 is transferred to roller 1,
The strong pressure between the rollers and the supporting material S may be damaged and the fixing performance may be deteriorated. Therefore, it is necessary to apply an anti-offset liquid such as silicone oil to the surface of the fixing roller, but the smooth surface coated with hard chrome has poor wettability, making it difficult to apply the anti-offset liquid evenly and uniformly. Therefore, if only a very small amount is applied, offset will occur partially due to the above-mentioned non-uniformity. Furthermore, if the coating amount is increased until this partial offset is eliminated, the two fuser rollers may slip and the image support material may not enter the nip between the two rollers. In addition, liquid accumulates at the entrance of the pressure contact portion of the pair of rollers that are in strong pressure contact as described above, and this contaminates the image support material S significantly.

Therefore, according to the present invention, a very small amount of anti-offset liquid can be uniformly applied even to the hard chrome plated pressure fixing roller.

That is, in the figure, reference numeral 8 denotes a coating member that is brought into contact with the roller 1 that presses the unfixed toner image supporting surface of the toner image supporting material S. This member 8 is made of a material, such as felt, paper, nonwoven fabric, or woven fabric, that is impregnated with a liquid and exudes the impregnated liquid. The coating member 8 is impregnated with a liquid in which silicone oil, for example, as an anti-offset liquid and polyethylene glycol ester as a surfactant are uniformly mixed.
This mixed solution is applied to. In this way, a small amount of silicone oil is added, which is sufficient to prevent offset due to the action of this surfactant.
It can be uniformly applied to the hard chrome plating surface of the fixing roller 1, and no offset occurs even locally. This is thought to be because the surfactant is interposed between the hard chrome plating and the anti-offset liquid such as oil, thereby improving the wettability of the anti-offset liquid.

The anti-offset liquid is preferably inert and lubricating in order to protect the chrome plated surface and to reduce friction between the two fixing rolls. In addition, the offset prevention liquid is not limited to silicone oil, and other mineral-based lubricating oils may also be used;
Silicone oil is the most suitable for safety reasons.
When a fibrous material is used as the application member 8 as described above, the viscosity of the offset prevention liquid is generally 50 to 50 at the temperature during operation of the fixing device (in the case of a pressure fixing device, this can be considered as room temperature). 1000CST,
In particular, it is convenient that the amount is about 100 to 500 CST, since the amount of exudation from the coating member 8 is adequate to prevent offset. Further, when a fibrous material is used as the application member 8 as described above, it is generally recommended to impregnate the application member 8 with the anti-offset liquid in an amount of 5 to 70% by weight, particularly 10 to 60% by weight.
This is advantageous because the amount of seepage from the base is adequate to prevent offset.

As the surfactant, nonionic surfactants such as the above-mentioned surfactants are preferable because of their excellent stability, and other examples of such nonionic surfactants include polyethylene glycol ether,
Polyvalent fatty acid esters, polyoxyethylene alkyl phenyl ethers, etc. can be used. However, ionic surfactants such as alkyl sulfate salts, alkyl amine salts, etc. can also be used. In any case, when using the fibrous coating member 8 as described above, it is recommended that the amount of liquid active agent impregnated is 1 to 30% by weight, particularly 3 to 20% by weight, to improve coating properties.
It is preferable because it has excellent wettability and wettability.

In addition, in addition to impregnating the coating member 8 with a mixture of anti-offset liquid and a surfactant and applying both liquids to the fixing roller 1 at the same time, the coating member 8 is impregnated with a surfactant and the fixing roller 1 is first coated with this interface. A coating member 8' coated with an activator and impregnated with an anti-offset liquid (for example, like member 8, a coated member 8' is made of felt, paper, woven fabric, etc.).
It is also possible to use a structure in which a fibrous material such as a nonwoven fabric can be used) is brought into contact with the roller 1, and the anti-offset liquid is applied next to the surfactant.

Further, as a means for applying the offset prevention liquid and surfactant, an application roller that rotates in contact with the roller 1 can also be used.

In addition to the fixing roller 1, the fixing roller 2 also has
Alternatively, the anti-offset liquid and surfactant may be applied only to the fixing roller 2 as described above.

Further, the present invention is particularly useful for pressure fixing devices in which the surface of the fixing roller is made of hard chrome plating, but is not limited thereto. In other words, it is very effective for a fixing device equipped with a fixing roller having a surface with poor wettability.

As described above, according to the present invention, offset can be effectively prevented on the entire surface with a small amount of anti-offset liquid, and staining of the toner image supporting member due to the liquid, destruction of the image due to roller slip, waste of liquid, etc. can be prevented. It is something.

Particularly in the conventional toner image supporting material, many offsets were observed at the leading edge, but the present invention completely eliminates this problem. Furthermore, offset was often seen in OHP films, but this was also completely improved.

[Brief explanation of drawings]

The figure is an explanatory diagram of an embodiment of the present invention, and 1 and 2 are fixing rollers, and 8 and 8 are coating members.

Claims (1)

[Scope of Claims] 1. In a fixing device that fixes an unfixed toner image by passing a support material supporting the unfixed toner image between a pair of rollers, the roller on the side in contact with the unfixed toner image A fixing device characterized in that an anti-offset liquid and a surfactant are applied. 2. The fixing device according to claim 1, wherein the offset prevention liquid and the surfactant are applied by the same means. 3. The fixing device according to claim 2, wherein the offset prevention liquid and the surfactant are mixed.