JPS5974579A - Fixing device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of an offset factor of a material to be fixed such as a toner and a resin material by giving an electrostatic charging agent having an amino modified silicone oil to the surface of a rotating body to vary the polarity of frictional electrostatic charging of the rotating body. CONSTITUTION:A negative toner image T formed by the electrophotographic method is fixed to an ordinary paper P having a thickness of several 10mu (70- 100mu normally) by a heat fixation device including a pressure roll 2 which is pressed to a heat roll 1 and is rotated while rubbing it, and a heat insulating nonwoven cloth 7 impregnated with an amino modified silicon oil is supported by a supporting member 8 under the pressure roll 2 and is provided slightly apart from the surface of the pressure roll 2. When the pressure roll 2 is pressed to the heat roll 1 and is rotated and is expanded to be brought into contact with the heat insulating nonwoven cloth 7, the amino modified silicone oil is given to the surface of the pressure roll 2 to obtain a positive surface potential by the frictional electrostatic charge to the ordinary paper P, and the negative toner is held strongly on the surface of the paper to prevent the offset.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fixing device installed in a recording device such as an electrophotographic device or an electrostatic recording device, and more specifically, the present invention relates to a fixing device installed in a recording device such as an electrophotographic device or an electrostatic recording device.

The present invention relates to a fixing device that extremely effectively prevents offset that occurs during pressure processing or heating and pressure processing.

Conventionally, offset TiJ4. What can be done to prevent this phenomenon is disclosed in Japanese Unexamined Patent Application Publication No. 1983-
It is disclosed in Japanese Patent Application Laid-open No. 55374 and Japanese Patent Application Laid-open No. 55-96970. A bias voltage of the same polarity as the toner image is applied by a corotron to a roller in contact with the image surface of the copy paper, for example, a toner image, or a toner is applied to a roller on the opposite side of the toner image surface. It is known to apply a bias voltage of opposite polarity. In other words, in the conventional device, a charge is forcibly applied from the outside of the rotating body. If the voltage was applied using a corona charger such as a corotron, the equipment would be large, complicated, and costly. In addition, when the voltage was applied using a bias roll, the practical effect was small and the piezo roll was easily smeared, making it impractical.

The present invention satisfactorily improves the above-mentioned conventional drawbacks with a simple configuration.

A main object of the present invention is to extremely effectively prevent an offset phenomenon to a rotating body, and another object of the present invention is to provide a fixing device that has stable fixing performance over a long period of time.

The present invention applies a charging agent containing amyl/modified silicone oil to the surface of the rotating body to vary the frictional charging polarity of the rotating body, thereby causing an offset of objects to be fixed such as toner and resin materials (coatings, etc.). This is to fundamentally prevent this from occurring.

Hereinafter, the present invention will be explained with reference to the drawings.

FIG. 1 is an explanatory diagram of an embodiment of the present invention. This figure shows a device in which a negative toner image T formed by electrophotography is fixed onto plain paper P having a thickness of several tens of microns (usually about 70 to 100 microns) using a heat fixing device.

A heating roller 1 has a heating heater 6 such as a halogen heater inside, and rotates in the direction of the arrow in response to driving force from a drive motor (not shown). Reference numeral 2 denotes a pressure roller, which is brought into pressure contact with the heating roller 1 and rotates by sliding.

This heating row 21 is made of a hollow roller core 12 made of metal such as aluminum, stainless steel, copper, etc., and a heat-resistant mold release resin layer 11 made of tetrafluoroethylene resin or the like is provided on the outer circumferential surface of the roller core 12 to a thickness of 20 to 100 μm.

The pressure roller 2 is rotatably supported by a bearing (not shown). The applying IE roller 2 is pressed against the heating roller 1 by a known pressing means (not shown) at least during fixing, and is provided on the outer peripheral surface of a metal roller core 22. One purpose of this configuration is to secure a pressure contact area d with the heating roller.

A temperature sensing element 4 such as a reamister or thermocouple is disposed in contact with the outer peripheral surface of the heating roller 1, and its detection signal is guided to a known control means (not shown) to control the temperature of the outer peripheral surface of the heating roller 1 ( The toner image is maintained at the melting temperature (by controlling the output of the heater 6 or the applied voltage, etc.).

6 is for removing foreign matter such as offset toner and paper dust that has adhered to the heating roller surface from the roller surface')') -
, and has a cleaning web 6□ made of a heat-resistant nonwoven fabric such as Nomex or Himeron impregnated with silicone oil for preventing offset. The cleaning web 61 is brought into contact with the heating roller by an elastic pressing roller 63. Also, this web 61 is moved from the supply roller 62 in small amounts by a driven take-up roller 64 (not shown) to the contact position. The new surface of the cleaning web 61 always comes into contact with the entire length of the surface of the heating roller 1.

51152 is a claw 1 for reliably separating the plain paper P as a recording material after fixing from each roller surface [11]. 7 is a woven heat-resistant nonwoven fabric impregnated with amino-modified silicone oil, and is normally spaced slightly from the surface of the pressure roller. Reference numeral 8 denotes a support member for this purpose, which is fixed to a substrate 9 of the device below the pressure roller 2.

When the copy switch is turned on, the heating roller 1 starts rotating and the pressure roller 2 starts rotating under pressure.

By pressing and rotating, the insulating elastic layer of the pressure roller receives heat from the heating roller and expands, and the amino-modified and amino/modified silicone oils are separated from the surface of the pressure roller. This can effectively prevent thermal deterioration of the amide/modified silicone oil.The skeletal structure of this amide/modified silicone oil is shown below.

When the above-mentioned amino-modified recon mail is applied to a single-pressure roller, it will have a positive surface potential due to the straightening of the friction zone with the plain paper P.

In the fixing device with the above-mentioned structure, the outer diameter of 1
A pair of rollers are brought into contact with each other at a total pressure of 60 kg, and 26 sheets/min of plain paper and Japanese Industrial Standard A6 size paper (roller circumferential speed 270
The fixing process was performed at a speed of (mm/sec). The toner uses negatively charged toner (negative toner).
When 500 my of toner was fixed on a sheet of A6 plain paper (the condition most likely to cause offset), when amino-modified silicone oil was applied, it was less than 1/4 of the amount when conventional methyl silicone oil was applied. The offset was reduced. The surface potential of the pressure roller at this time was -6000V or more when applying conventional silicone oil, compared to -6000V or more.
The polarity was reversed to +2400 V due to friction during fixing.

As a result of the above, it is thought that the offset will decrease due to the following factors. That is, when a positively charged positive latent image is transferred onto plain paper after being developed with negative toner, the plain paper is given a positive charge and is transferred by electrostatic attraction with the negative toner.

That is, at this point, it is important that the plain paper is heated to a glass level.

Thereafter, in the fixing process, when the plain paper P is charged by frictional separation with the pressure roller 2 when passing through the nip portion, the amino-modified silicone oil acts and the pressure roller is highly charged positively. In other words, when the plain paper P is negatively charged, which is opposite to the positive charge that should hold negatively charged toner, it becomes K. The inventors of the present invention elucidated this phenomenon by considering that offset is related to electric potential rather than electric charge. The small pressure roller has a surface that has a much higher potential than the paper, and exerts a large electrostatic attraction on the negative toner on the plain paper to the extent that the charge on the back surface of the paper can be ignored. In other words, during fixing, the negative toner is strongly held on the paper surface, so offset can be prevented.

In order to examine the sustainability of the above effects, 1) 10 ice sheets were impregnated with 10 cc of Niamino-modified silicone oil, and 20,000 copies were made intermittently at one page per minute under the configuration conditions shown in Figure 1 above. However, 20. (It was confirmed that the same effect as the above result was obtained even after JOO sheets.

In addition, after uniformly applying 5 cc of amyl/modified silicone oil [] to the surface of the pressure roller (removing the charging agent application members 6 and 7 shown in Fig. 1), the same intermittent copying as above was performed. Even after printing 2,000 sheets, the effect decreased slightly, but it was confirmed that the offset was reduced to 1/3 compared to the conventional method.

As is clear from the above, by applying the amine-modified silicone oil to the rotating body that comes into contact with the surface of the recording material on the side opposite to the side on which the unfixed negative to-be-fixed object is fixed, Better offset prevention can be achieved.

The amino-modified silicone oil may be applied via an application roller, or may be applied to the rotating body at predetermined rotational speeds using an eccentric cam for approaching and separating. Further, this amino-modified silicone oil may be impregnated and added into the surface layer of the rotating body in advance. Furthermore, when impregnated or added, the durability can be further improved by separating the rotating body from the heat source or heating roller during non-fixing periods using known means.

Thermal theory The present invention can be applied to any rotating body that comes into contact with a recording material and causes a frictional factor that offsets the fixing object (for example, one having an insulating layer thicker than the thickness of the recording material), and is applicable to pressure fixing devices. Needless to say, it can also be applied.

By using this amino-modified silicone oil, it is possible to prevent offset for a long period of time by just applying it once to fix thousands to tens of thousands of sheets, so it is inexpensive and does not require a complicated mechanism.
It is highly practical.

As described above, the present invention can effectively prevent off-ceratra on the surface of the rotating body over a long period of time by a simple method of applying amino-modified silicone oil to the surface of the rotating body.

[Brief explanation of drawings]

FIG. 1 shows a model 9 M of a one-shot embodiment of the present invention. Material.

Claims (2)

[Claims] (1) A fixing device having a rotating body that comes into contact with the back side of the fixing surface of the recording material in order to fix a negative fixing target onto a recording material, the rotating body having amino-modified silicone oil on the surface thereof. A fixing device characterized by applying a charging agent. (2) The fixing according to item 1 of the patent claim, wherein the charging agent is applied to the surface of the rotating body or impregnated or added to the surface of the rotating body. Device.