JPH07271233A - Pressure roller for fixing - Google Patents

Abstract

PURPOSE:To decrease hardness of a silicone rubber layer by forming continuous hollow holes along the longitudinal direction of the silicone rubber layer having good mold releasing property so that pressure is absorbed by the hollow holes. CONSTITUTION:The pressure roller for fixing is produced by forming a liquid silicone rubber layer 1 on a core metal 3. In this silicone rubber layer 1, continuous hollow holes 2 are formed in parallel to the core metal 3. The surface hardness of the silicone rubber layer 1 is preferably <=15 degrees measured with a JIS-A hardness meter. Further, by forming a fluorocarbon resin coating layer on the surface of the silicone rubber layer l, the obtd. pressure roller for fixing has excellent releasing property and low hardness. In this method, the surface hardness of the fluorocarbon resin coating layer is preferably <=60 degrees measured with an Asker-C hardness meter. The cross-sectional shape and position of the hollow holes 2 are not limited but the holes are uniformly distributed in the whole silicone rubber layer 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing pressure roller for heating and fixing a toner image on a carrier such as paper in an image forming apparatus such as a copying machine, a facsimile machine or a laser printer.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a facsimile machine or a laser printer, as one of the methods for fixing a toner image on a carrier by heating, a carrier is fixed between a heat fixing roller and a pressure roller. The method is generally widely used.

As the pressure roller, aluminum,
A metal core metal such as iron having a silicone rubber layer formed thereon is widely used.

It is generally known that the fixability of toner is affected by the pressure-bonding width (hereinafter referred to as the nip width) between the heat-fixing roller and the pressure roller, and the larger the nip width, the higher the fixability.

However, normally, the liquid silicone rubber used for the pressure roller and having a good releasability has a rubber hardness measured by a JIS A type hardness meter of about 16 degrees at the minimum, and the nip width should be increased. Is difficult.

In order to increase the nip width, it has been practiced to use a millable silicone rubber foam having a low rubber hardness and a low hardness liquid silicone rubber (Hs15 to Hs5).

Since the millable silicone rubber foam is inferior in releasability, a coating layer having a good releasability on the surface thereof, for example,
Since it is necessary to provide a fluororesin tube layer, a liquid silicone rubber layer, and the like to form a multilayer structure, there are problems that the types of materials used increase, the manufacturing process becomes complicated, and the cost increases.

Low-hardness liquid silicone rubber has not been mass-produced because of problems such as surface tackiness and repulsive force.

[0009]

Accordingly, it is an object of the present invention to provide a millable silicone rubber foam having a multi-layer structure, or
An object of the present invention is to provide an inexpensive low-hardness fixing pressure roller that uses a normal liquid silicone rubber without using the low-hardness liquid silicone rubber.

[0010]

As a result of various studies to achieve the above object, the inventors of the present invention have found that hollow holes continuous in the length direction are formed in a silicone rubber layer formed of liquid silicone rubber. They found that they should be provided, and completed the present invention.

That is, according to the present invention, in a fixing pressure roller comprising a cored bar and a liquid silicone rubber layer formed on the cored bar, continuous hollow holes are provided in the silicone rubber layer in parallel with the cored bar. The surface hardness of the silicone rubber layer is measured by a JISA hardness tester.
It is preferably 15 degrees or less.

Further, by providing a fluororesin coating layer on the surface of the silicone rubber layer, a fixing pressure roller having excellent releasing property and low hardness can be provided. At this time, the surface hardness of the fluororesin coating layer is preferably 60 degrees or less as measured by an Asker C type hardness meter.

[0013]

In the present invention, hollow holes which are continuous in the lengthwise direction are formed in the silicone rubber layer having good releasability,
The hollow holes absorb the pressing force and reduce the hardness of the silicone rubber layer.

Accordingly, it is possible to provide a low-cost fixing pressure roller without increasing the number of working steps as in the case of using the millable type silicone rubber foam and providing a coating layer having a good releasing property on the surface. You can

[0015]

1 is a longitudinal sectional view showing an example of a fixing pressure roller of the present invention, FIG. 2 is a sectional view taken along the line A--A of FIG.
1 is a cross-sectional view taken along the line AA when a fluororesin coating layer is provided, 1 is a liquid silicone rubber layer, 2 is a hollow hole, 3 is
Indicates a core metal, and 4 indicates a fluororesin coating layer.

The cross-sectional area and the number of the hollow holes 2 are appropriately selected according to the hardness of the silicone rubber layer 1 required,
In order to obtain a hardness of 15 degrees or less as measured by a JISA type hardness meter which is usually required, the cross-sectional area of the hollow hole is 0.5 to 7.5.
mm ² / hole, and the total cross-sectional area of the hollow holes 2 is preferably 5 to 25% of the cross-sectional area of the silicone rubber layer 1.

There are no particular restrictions on the cross-sectional shape of the hollow holes 2 and the position where they are arranged, but it is desirable that they are evenly arranged over the entire silicone rubber layer 1.

The silicone rubber used in the present invention is
Liquid silicone rubber normally used for a fixing pressure roller, for example, XE12-A9438A / B (manufactured by Toshiba Silicone Co., Ltd.) and the like.

As the fluororesin, polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PF) is used.
A) and the like, and the thickness of the coating layer is 30 to 150 μm.
It is preferable that

In order to form the present invention, first, the core metal 3 and the wire for the hollow hole 2 are set in a mold such as injection molding or casting. Next, liquid silicone rubber is injected into the mold and heated to cure and cure the silicone rubber. Then, the wire is pulled out to form the hollow hole 2.

The heating temperature during vulcanization is 100 to 150 ° C.
A heating time of 30 to 60 minutes is suitable. Also, the material of the wire is not particularly limited as long as it does not melt at the heating temperature, does not deform, and does not adhere to the silicone rubber,
Examples thereof include polytetrafluoroethylene fine wire and stainless steel wire.

For example, a liquid silicone rubber (XE12-A9438A) is placed on a core metal having a diameter of 15 mm and a length of 300 mm.
/ B manufactured by Toshiba Silicone Co., Ltd.) to have a thickness of 5 mm. At this time, the diameter of 1.
Eight 5 mm stainless steel wires are installed at equal intervals, and after vulcanization at 140 ° C. for 30 minutes, the stainless steel wires are pulled out, and as shown in FIGS. 1 and 2, eight hollow holes are formed in the silicone rubber layer 1. A fixing pressure roller having 2 is obtained.

The pressure roller thus obtained has a hardness of 15 degrees as measured by a JISA type hardness meter and a nip width of 3.0 mm when pressed against a fixing heating roller with a load of 3 kg. When the hollow hole is not provided, the hardness is 22 degrees and the nip width is only 2.4 mm.

Further, under the same conditions, a PF of 50 μm when formed
When the A coating layer is provided, the pressure roller has a hardness of 55 degrees measured by an Asker C type hardness meter, and the fixing heating roller has a hardness of 3K.
The nip width when pressed with a load of g is 2.7 mm, and when the hollow hole is not provided, the hardness is 62 degrees and the nip width is only 2.0 mm.

[0025]

According to the present invention, a fixing pressure roller having a silicone rubber layer having a low hardness and good releasability can be provided at low cost.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an example of a fixing pressure roller of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3A shows another example of the fixing pressure roller of the present invention.
It is a sectional view taken along line A-A.

[Explanation of symbols]

 1 Liquid Silicone Rubber Layer 2 Hollow Hole 3 Core Bar 4 Fluororesin Coating Layer

Claims (3)

[Claims] 1. A fixing pressure roller formed by forming a liquid silicone rubber layer on a core metal, wherein a hollow hole continuous in parallel with the core metal is provided in the silicone rubber layer. Pressure roller. 2. The fixing pressure roller according to claim 1, wherein the silicone rubber layer has a surface hardness of 15 degrees or less as measured by a JIS A hardness meter (1 Kgf). 3. The fixing pressure roller according to claim 1, wherein the silicone rubber layer having the fluororesin surface layer has a surface hardness of 60 degrees or less as measured by an Asker C type hardness meter (1 Kgf).