JPH09171316A - Fixing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing method capable of obtaining an excellent fixed image by eliminating the disturbance of the releasing effect of a silicone oil with which a fixing roller is coated and making the thermal oxidation of the silicone oil hard so as to prevent an offset over a long period. SOLUTION: In the fixing method for heating/fixing toner T on a fixing paper P passing this fixing paper P having the toner T through a thermal roller fixing device provided with a heating roller 1 and a pressure roller 3, the thermal roller fixing device is provided with a releasing agent coating member 4 for coating the heating roller 1 with a releasing agent and a cleaning member 5 which is abutted on the surface of the heating roller to clean it. The heating roller 1 is coated with a silicone oil incorporating an antioxidant as the releasing agent by the releasing agent coating member 5 and a surplus of the silicone oil incorporating the antioxidant after coating is removed by the cleaning member 5, to obtain a thin layer. After the surface of the heating roller is cleaned, the toner T on the fixing paper P is heated/fixed thereon.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing method in which fixing paper having toner is passed through a heat roller fixing device and the toner on the fixing paper is heated and fixed on the fixing paper.

[0002]

2. Description of the Related Art A heat roller fixing system is often used as a fixing device for electrophotographic copying machines and printers. This method has many advantages such as high thermal efficiency, small device size, and high safety, and is widely used from high-speed machines to popular machines. A problem of the heat roller fixing method is a toner offset phenomenon. To prevent offset, the surface of the fixing roller is covered with fluororesin or silicone rubber.

In order to further improve the releasability, silicone oil is applied to the fixing roller as a release agent.

The surface temperature of the fixing roller is usually 150.degree.
It is controlled at around 00 ℃. However, in the non-sheet passing area of the fixing roller, which is caused by passing small size paper,
In particular, the surface temperature is 230 ° C to 250 ° C when continuous paper is passed.
The temperature may reach ℃.

By the way, the dimethyl type silicone oil mainly used as a release agent is relatively stable at 180 ° C. or lower, but at a temperature of 200 ° C. or higher, a fairly active thermal oxidation reaction occurs to polymerize the polymer and the viscosity. Is known to rise.

Further, since the silicone oil applied to the fixing roller is in the form of a thin film, its surface area is relatively large and the thermal oxidation reaction is likely to be promoted. In particular, when the set temperature of the heat roller fixing device exceeds 180 ° C. or when fixing paper of a size smaller than the maximum paper passing size is frequently passed, thermal oxidation of the silicone oil is easily promoted and the surface of the fixing roller is likely to be promoted. There is a problem in that the viscosity of the silicone oil applied to the toner becomes high, the releasability deteriorates, and offset easily occurs.

Further, the silicone oil having a phenyl group or a chlorophenyl group bonded thereto has a high thermal oxidation temperature, but the cost is higher than that of the dimethyl type silicone oil, and the temperature is 150 ° C.
The viscosity was too low under conditions of use up to 200 ° C. and it was unsuitable for use as a release agent for a fixing roller.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a fixing method which solves the above problems.

It is an object of the present invention to provide a fixing method capable of preventing offset for a long period of time and obtaining a good fixed image.

It is an object of the present invention to prevent the release effect of silicone oil as a release agent applied to a fixing roller of a heat roller fixing device from being impaired, and to prevent the silicone oil from being easily thermally oxidized. It is an object of the present invention to provide a fixing method in which a releasing agent is effectively made to function and offset is prevented to obtain a good fixed image.

[0011]

The above object is achieved by the following constitution of the present invention.

According to the present invention, a fixing roller containing a toner is passed through a heat roller fixing device having a heating roller and a pressure roller that presses the fixing roller so that the fixing sheet can be passed through the fixing roller. In the fixing method of heating and fixing the toner on the fixing paper, the heating roller fixing device includes a releasing agent applying member for applying a releasing agent to the heating roller, and the heating roller surface abutting on the heating roller surface. A cleaning member for cleaning the heating roller, and a silicone oil containing an antioxidant as a release agent is applied to the heating roller by the releasing agent applying member, and the oxidation prevention applied to the heating roller by the cleaning member is performed. After removing the excessive amount of the agent-containing silicone oil to thin the layer and cleaning the surface of the heating roller, the toner on the fixing paper is heated and fixed on the fixing paper. A fixing method comprising Rukoto.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a fixing device according to an embodiment capable of carrying out the fixing method of the present invention.

The heating roller 1 has a fluororesin film formed on a hollow core metal. Reference numeral 2 denotes a halogen heater as a heating source. The pressure roller 3 is formed such that a silicon rubber layer is formed on a cored bar, and the pressure roller 3 rotates by pressing against a heating roller.
The release agent coating member 4 is obtained by impregnating a fluororesin in a porous state with silicone oil containing an antioxidant. The cleaning blade 5 is made of fluorine-based heat resistant rubber and is pressed against the heating roller 1. When the heating roller 1 is heated, the release agent coating member 4 is also heated and the silicone oil is leached out and supplied to the heating roller 1.

The excessively supplied silicone oil is scraped off by the cleaning blade 5 as a cleaning member when the heating roller 1 rotates, and is thinned on the surface of the heating roller 1 to release the heating roller 1. Improve sex.

When the paper passes between the pair of fixing rollers, a part of the silicone oil adheres to the paper, and the silicone oil is consumed as the paper is passed. Leaching from the release agent coating member 4 and evaporation due to heating often occur from the low molecular weight silicone oil, and as the number of sheets passed increases, the proportion of polymer components in the silicone oil increases.

When no antioxidant is added to the silicone oil, the silicone oil on the heating roller is thermally oxidized to crosslink the polymers, gradually increasing the viscosity and increasing the molecular weight to 10.
It reaches the limit of 10,000 and deteriorates the releasability of the heating roller.
The offset increases from about 00 sheets. The offset toner is scraped off from the surface of the heating roller by the cleaning blade together with the silicone oil, but the scraped toner accumulates, and cleaning failure occurs from about 8000 sheets of paper passing through, which stains the fixing paper.
The reason why this cleaning failure occurs is that thermal oxidation of the silicone oil that has been scraped off by the cleaning member and remains is particularly pronounced, so that the increase in viscosity is promoted and the thin layer of the silicone oil of the cleaning member is promoted. This is because the silicone oil having a higher viscosity is reduced and the silicone oil having a high viscosity is scraped off by the cleaning member and conveyed to the fixing portion.

Therefore, conventionally, it has been necessary to perform maintenance of the fixing device using approximately 10,000 sheets of paper as a guide, discard the accumulated offset toner, and clean the roller and the cleaning blade.

It has been found that when about 15 ppm of iron is added to silicone oil as an antioxidant, the releasability of the roller is not deteriorated and the offset hardly occurs even after passing 20,000 sheets.

Therefore, it is possible to prevent the paper from being soiled due to the offset, to extend the maintenance interval, and to reduce the labor for cleaning.

Further, since there is almost no decrease in the amount of silicone oil due to thermal oxidation, it is possible to extend the interval for replenishing silicone oil and the interval for exchanging the release agent coating member. Further, since the offset hardly occurs, the pressing force of the cleaning blade can be reduced, so that the abrasion of the roller by the cleaning blade is reduced and the life of the roller can be extended.

Instead of the release agent for silicone oil containing 15 ppm of iron as the antioxidant, dimethyl silicone oil was used as an antioxidant for red iron oxide (Fe).
_It has been found that even if a release agent containing about 15 ppm of ₂ O ₃ ) is used, the releasability of the roller does not deteriorate, and offset does not occur even after passing 20,000 sheets. Other,
Any substance that suppresses thermal oxidation of silicone oil, such as a redox metal such as copper, tin, silver or zinc, or a complex of these metals can be used as an antioxidant.

The content of the antioxidant in the silicone oil is 1 to 1000 ppm, preferably 5 to 100 ppm from the standpoint that the antioxidant effect of the silicone oil is sufficiently exhibited and the releasing effect of the silicone oil is not impaired.

If the content of the antioxidant in the silicone oil is too small, the effect of suppressing the thermal oxidation of the silicone oil due to the addition of the antioxidant is small, and a long-term good offset resistance is obtained over many sheets. Of the silicone oil is difficult to maintain, and when the amount is too large, the releasing effect of the silicone oil is hindered, and the offset resistance is lowered from the initial stage.

[0025]

According to the present invention, a releasing agent is applied to a heating roller and a heating roller fixing device having a pressure roller that presses a fixing sheet so that the fixing sheet can pass through the heating roller. And a cleaning member for contacting the surface of the heating roller to clean the surface of the heating roller, the silicone containing an antioxidant as a releasing agent is applied to the heating roller by the releasing agent application member. After the oil is applied and the cleaning member removes an excess of the antioxidant-containing silicone oil applied to the heating roller to form a thin layer, the surface of the heating roller is cleaned and then the fixing paper on the fixing paper is removed. Since the toner is heated and fixed on the fixing paper, it is possible to suppress thermal oxidation of the release agent to prevent deterioration of the releasability, and to exert good offset resistance for a long period of time. , The effect of thinning the silicone oil by the cleaning member and the scraping and collecting effect of the toner can be maintained satisfactorily for a long period of time, and the occurrence of defective cleaning can be suppressed. Therefore, the offset and the stain of the fixing paper can be suppressed for a long time. can do.

[Brief description of the drawings]

FIG. 1 is a diagram showing a cross-sectional view of a heat roller fixing device that can carry out the present invention.

[Explanation of symbols]

 1 Fixing Roller 2 Heater 3 Pressure Roller 4 Release Agent Applying Member 5 Cleaning Blade 6 Applying Roller P Fixing Paper T Toner

Claims (4)

[Claims] 1. A heat roller and a heat roller fixing device having a pressure roller that presses the heat roller so that the heat roller can be passed through the heat roller. A heating roller fixing device, wherein the heating roller fixing device contacts the heating roller surface with a releasing agent applying member for applying a releasing agent to the heating roller, and cleans the heating roller surface. A cleaning member for controlling the heating roller is applied to the heating roller with a silicone oil containing an antioxidant as a releasing agent, and the cleaning member contains an antioxidant applied to the heating roller. After removing an excessive amount of silicone oil to form a thin layer and cleaning the surface of the heating roller, heat fixing the toner on the fixing paper to the fixing paper. Fixing method according to claim. 2. The fixing method according to claim 1, wherein the release agent applying member has a porous member impregnated with the antioxidant-containing silicone oil. 3. The fixing method according to claim 1, wherein the cleaning member has a cleaning blade made of fluorine-based heat resistant rubber. 4. The fixing method according to claim 1, wherein the silicone oil comprises dimethyl silicone oil.