JP2001265144A - Thermal fixing roll - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal fixing roll having superior paper-passability without generating any charges in the thermal fixing roll 2, when an image carrier 4 is passed through a fixing device 1, even in an environment of high humidity. SOLUTION: The thermal fixing roll is provided with a metal core and plural elastic layers formed successively and concentrically on the metal core with different materials. The elastic layer which is the lowest layer among the plural elastic layers consists of a material, having surface resistivity of 1×109 Ω or lower, and the elastic layer being the outermost layer consists of material having the surface resistivity range of 1×109 Ω and 1×1016 Ω.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrophotographic copying machine.
The present invention relates to a fixing device used in an image forming apparatus such as a printer, and particularly to a technical field of a heat fixing roller.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus such as a copying machine, a printer, and a facsimile, a latent image is formed according to an image by irradiating a charged photoconductive material with light corresponding to the image. . The latent image is developed by electrostatically adsorbing toner on the latent image, and the developed toner image is electrostatically transferred and adsorbed on an image carrier such as recording paper. When the image carrier on which the toner image has been electrostatically attracted passes through the fixing device, heat and pressure are usually applied to fix the toner image to the image carrier. The image forming apparatus of the electrophotographic system is as described above in brief. However, since this technique is well known, no further description will be given.

FIG. 1 is an example of a sectional view of a fixing device.
It is a figure for explaining the outline of the example of the prior art and the present invention. FIG. 2 is a cross-sectional view of a heat fixing roller used in the fixing device of FIG.

The fixing device 1 includes a heat fixing roller 2 and a pressure roller 3. The pressure roller 3 is a cylindrical member made of a rigid material such as metal, and is biased by a spring 6 or the like. The member is pressed toward the heating roller 2.
The image carrier 4 to which the toner 5 has been electrostatically attracted is conveyed from the left side in the figure in the direction of arrow c. The heat fixing roller 2
A cylindrical cored bar 8 made of metal such as aluminum and an elastic layer 9
A heater 7 is provided inside, and is driven to rotate in the direction of arrow a by a drive source (not shown). Following the rotation of the heat fixing roller 2, the pressure roller 3 rotates in the direction of arrow b.

The elastic layer 9 is deformed by the pressure of the pressure roller 3 to form a nip n having a width. When the transported image carrier 4 passes through the nip portion n, it is sufficiently heated within this width, and the toner 5 permeates between the fibers and the like of the image carrier 4 by pressure.

As shown in FIG. 2, the elastic layer 9 is further formed of several layers, the lowermost layer 91 of a relatively thick silicone rubber, which is the lowermost layer in contact with the aluminum core 8, and the fluorine layer thereon. It is composed of several oil-resistant intermediate layers 92 made of rubber or the like, and an outermost layer 93 of relatively thin silicone rubber impregnated with the outermost silicone oil.

Usually, silicone rubber has a surface resistivity of 1 ×.
10 ¹⁶ Ω or more insulative, image carrier (recording paper)
By contacting and separating from the sample No. 4, static electricity is generated, and a very large negative charge property is exhibited.

For this reason, when the image carrier 4 passes through the fixing device 1, it is strongly sucked and wound around the heating / fixing roller 2, thereby causing a problem that paper passing failure occurs.

To address this problem, the lowermost layer 91
A conductive filler is added to a relatively thick layer of silicone rubber, and the surface resistivity of the silicone rubber is 1 × 1
Techniques for reducing the resistance to less than ⁰⁹ Ω are known. By doing so, the generated electrostatic charges are dissipated toward the cored bar 8 to prevent winding.

[0010]

However, in a high-humidity environment, a certain amount of electric charge is generated even by such a conductive treatment at 1 × 10 ⁹ Ω or less, which is not sufficient. In addition to the fact that the stiffness 4 is reduced by absorbing moisture, wrapping may still occur.

The present invention provides a heat-fixing roller which is excellent in paper-passing property without generating charge on the heat-fixing roller 2 when the image carrier 4 passes through the fixing device 1 even in such a high humidity environment. That is the task.

[0012]

The above object is achieved by the following means in the present invention. That is, the heat-fixing roller of the first invention includes a metal core, and a plurality of elastic layers formed on the core in turn, each of which is different from each other and concentric with each other, Wherein the lowermost elastic layer of the plurality of elastic layers is made of a material having a surface resistivity of less than 1 × 10 ⁹ Ω,
The outermost elastic layer of the plurality of elastic layers is made of a material having a surface resistivity of less than 1 × 10 ¹⁶ Ω. In addition,
Here, the surface resistivity is a surface resistivity obtained by a JIS K6911 test method.

A heat fixing roller according to a second aspect of the present invention is the heat fixing roller according to the first aspect, wherein each of the plurality of elastic layers is made of silicone rubber or fluorine rubber. The heat fixing roller according to a third aspect is the heat fixing roller according to the second aspect,
The outermost elastic layer of the plurality of elastic layers is made of fluoro-modified silicone rubber. The heat-fixing roller according to a fourth invention is the heat-fixing roller according to the second invention, wherein the outermost elastic layer among the plurality of elastic layers is made of dimethyl silicone rubber or phenyl-modified silicone rubber. And using wet silica as a filler.

In the heat fixing roller having the above-described structure, even in a high humidity environment where the rigidity of the image carrier (transfer paper) is reduced, electric charge is applied to the heat fixing roller when the image carrier passes through the fixing device. It is excellent in paper-passing properties without generation.

[0015]

1 and 2 are used as they are in this embodiment. The heat fixing roller 2 has a lowermost layer 91, an intermediate layer 92 and an outermost layer 93 around the cored bar 8. The lowermost layer 91 has a relatively large thickness and is made of silicone rubber or fluororubber to which a conductive filler is added. The middle layer 92 is a layer having oil resistance such as silicone rubber or fluororubber. Or it consists of a plurality of layers.

The outermost layer 93 is made of silicone rubber or fluorine rubber impregnated with silicone oil. Outermost layer 93
Can be a fluoro-modified silicone rubber. Further, the silicone rubber of the outermost layer 93 can be dimethyl silicone rubber or phenyl-modified silicone rubber, and wet silica can be used as the filler.

As described above, the heat fixing roller 2 is charged to a constant potential by static electricity generated by the contact and separation of the image carrier 4 and the heat fixing roller 2. Is electrostatically attracted to the heat fixing roller 2.

In the present invention, by adjusting the surface electric resistivity of the lowermost layer 91 and the outermost layer 93, the image carrier 4 can be transferred to the heat fixing roller 2 without affecting the releasability.
Is prevented from winding. To adjust the surface electric resistivity of the outermost layer 93, a conductive filler is added in such an amount that does not affect the releasability.

FIG. 3 shows that when the surface resistivity of the lowermost layer 91 and the surface resistivity of the outermost layer 93 are combined at various values.
The table shows the passability and releasability (to the extent that the toner does not adhere to the heat fixing roller) in a high humidity (for example, room temperature of 30 ° C., relative humidity of 85%) environment.

The surface resistivity of the lowermost layer 91 is 1 ×
10 ¹⁶ Ω or more, 1 × 10 ⁹ Ω or more and 1 × 10 ¹⁶ Ω
Less than 1 × 10 ⁹ Ω, and the outermost layer 93 is 1 × 10 ¹⁶ Ω or more and 1 × 1 Ω or less.
The region of less than ⁰⁹ Ω was examined. In the table, ○ mark is good,
The mark "x" means that the sample was not satisfactory because it was defective, and the mark "△" means that the sample could not be judged good or bad. The surface resistivity is
This is the surface resistivity obtained by the JIS K6911 test method.

As can be seen from the table, when both the outermost layer 93 and the lowermost layer 91 have a surface resistivity of 1 × 10 ¹⁶ Ω or more, the releasability is satisfactory, but the paper passing property is not satisfactory. Thus, such a heat fixing roller 2 cannot be used substantially.

The outermost layer 93 is 1 × 10¹⁶Ω or more
With a drag rate, the lowest layer 91 is 1 × 10 ⁹Surface resistance less than Ω
If it has a rate, it is satisfactory in the releasability, but
I can't judge whether sex is good or bad.
Such a heat fixing roller 2 can be substantially used.
Absent.

The outermost layer 93 has a surface resistivity of 1 × 10 ⁹ Ω or more and less than 1 × 10 ¹⁶ Ω, and the lowermost layer 91 has a surface resistivity of 1 × 10 ¹⁶ Ω or less.
When it falls within the range of less than × 10 ⁹ Ω, the paper-passing property and the releasability are satisfactory, and such a heat-fixing roller 2 can be used favorably.

When the outermost layer 93 has a surface resistivity of less than 1 × 10 ⁹ Ω and the lowermost layer 91 has a surface resistivity of less than 1 × 10 ⁹ Ω, there is a point at which satisfactory releasability is not obtained. No. 2 cannot be used well.

From the above, the lowermost layer 91 has a surface resistivity of less than 1 × 10 ⁹ Ω, and the outermost layer 93 has a surface resistivity of 1 × 10 ⁹ Ω.
A heat-fixing roller that falls within the range of Ω or more and less than 1 × 10 ¹⁶ Ω can satisfy the paper-passing property and the releasability, so the present invention employs this value range.

[0026]

According to the present invention, an image carrier (transfer paper)
Even in a high-humidity environment in which the rigidity of the image carrier decreases, a heat-fixing roller having excellent paper-passing properties can be obtained without generating charge on the heat-fixing roller when the image carrier passes through the fixing device. .

[Brief description of the drawings]

FIG. 1 is an example of a cross-sectional view of a fixing device, and is a diagram for explaining an outline of a conventional technique and an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a heat fixing roller used in the fixing device of FIG.

FIG. 3 is a table showing the sheet passability and the releasability in a high humidity environment when the surface resistivity of the lowermost layer 91 and the surface resistivity of the outermost layer 93 are combined with various values. It is.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 fixing device 2 heat fixing roller 3 pressure roller 4 image carrier 5 toner 6 spring 7 heater 8 core metal 9 elastic layer 91 bottom layer 92 middle layer 93 outermost layer n nip portion

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F16C 13/00 F16C 13/00 E (72) Inventor Tsuneshi Takahashi 2-3 Azuchicho, Chuo-ku, Osaka-shi, Osaka No. 13 Osaka International Building Minolta Co., Ltd.F-term (reference) 4J002 CP031 CP032 CP081 DJ016 GM00 GS00

Claims (4)

[Claims] 1. A heat fixing roller comprising: a metal core; and a plurality of elastic layers formed on the core in a sequential manner and concentric with each other using different materials. The lowermost elastic layer of the plurality of elastic layers is made of a material having a surface resistivity of less than 1 × 10 ⁹ Ω, and the outermost elastic layer of the plurality of elastic layers has a surface resistivity of Is a material having a particle size of less than 1 × 10 ¹⁶ Ω. 2. The heat fixing roller according to claim 1, wherein each of the plurality of elastic layers is made of silicone rubber or fluorine rubber. 3. The heat fixing roller according to claim 2, wherein an outermost elastic layer of the plurality of elastic layers is made of a fluoro-modified silicone rubber. 4. The heat fixing roller according to claim 2, wherein the outermost elastic layer among the plurality of elastic layers is made of dimethyl silicone rubber or phenyl-modified silicone rubber, and is wet-typed as a filler. A heat fixing roller using silica.