JP2691725B2 - Heat fixing roller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a heat fixing roller used in a heat fixing unit of an electronic copying machine or the like.

(Prior Art) Conventionally, a heat fixing roller fixing method has been widely used as a fixing method for an electronic copying machine or the like. In this heat fixing roller fixing method, the toner image on the copy paper is directly heated and melt-pressed between the two rollers of the heat fixing roller and the pressure roller, so that the fixing efficiency is high, and the roller serves as a copy paper conveyance unit. Since it also serves as a mechanism, it is possible to make the mechanism mechanically compact, which is also suitable for speeding up. As such a heat fixing roller, one having a fluororesin layer provided on a metal core shaft of iron, aluminum or the like to improve releasability from the toner,
Alternatively, a rubber layer such as silicone rubber or fluororubber provided on a metal core shaft to impart elasticity to the roller, and a fluororesin layer provided on the surface via the rubber layer is generally used. As a method for providing the fluororesin layer, for example, electrostatic powder coating, dispersion coating or the like is generally performed.

In such a heat fixing roller, a halogen lamp or the like is generally arranged as a heat source inside the metal core shaft to perform fixing by heat transfer from the inside, but since the heat source and the roller surface are separated from each other, Heat transfer loss may be large,
The power consumption of the heat source accounted for most of the power consumption of the electronic copying machine. Further, since it takes time to transfer heat from the heat source to the roller surface, some waiting time is inevitable at the time of starting.

By the way, with the rapid spread of electronic copying machines in recent years,
Various requirements such as speeding up and energy saving have been strengthened, and a heat fixing roller having lower power consumption and a shorter waiting time at the start has been demanded. Various heat fixing rollers are being developed to meet these demands. For example, an electric resistance heating element layer is arranged near the surface of the roller and an electric current is passed through the electric resistance heating element layer to generate heat from the electric resistance heating element layer as a heat source. A heat fixing roller designed for fixing has been developed. When such an electric resistance heating element layer is provided, insulating layers are required above and below the surface of the electric resistance heating element layer in order to prevent leakage of electricity. This insulating layer is often formed by plasma spraying a metal oxide such as aluminum oxide.

The roller provided with such an electric resistance heating element layer directly heats the roller surface as compared with the above-mentioned conventional heat fixing roller, so that heat transfer loss is small, thermal efficiency is good, and time required for heat transfer is also short. It has a number of advantages, including a simple structure and excellent safety.

(Problems to be Solved by the Invention) However, in a heat fixing roller provided with such an electric resistance heating element layer, when a fluorine resin layer is provided on the roller surface in order to improve releasability from the toner, the conventional fixing roller Depending on the method such as electrostatic powder coating or dispersion coating, it is difficult to obtain a good fluororesin layer. This is because the surface of the insulating layer provided outside the electric resistance heating element layer by the above-mentioned method tends to be rough instead of smooth. When a fluororesin is electrostatically powder coated on the surface of such a rough insulating layer, there is a problem that the coating efficiency is poor and pinholes and the like are likely to occur. Further, when such a rough surface is subjected to dispersion coating, there are disadvantages such as cracking during baking of the fluororesin after coating, as well as in terms of coating efficiency, and the addition of roller-shaped articles. There was also a problem that the dispersion coating of was originally not very productive.

The present invention has been made in order to solve such a conventional problem, excellent thermal efficiency, having a fluorine resin layer having a uniform film thickness and a smooth surface, and excellent releasability from a toner, It is an object of the present invention to provide a heat fixing roller which is easy to manufacture.

[Structure of the Invention] (Means for Solving the Problems) The present invention is to provide a fluororesin layer by heating a heat-shrinkable fluororesin tube on a roller surface and then heating and fusing the tube. After adhering the first insulating layer, the electric resistance heating element, the second insulating layer, and the heat-shrinkable fluororesin tube on the metal core shaft, heating is performed at a temperature equal to or higher than the melting temperature of the fluororesin for fusion bonding. It is characterized in that a fluororesin layer thus formed is sequentially provided.

The first and second insulating layers can be provided with a metal oxide such as aluminum oxide by a method such as plasma spraying.

As the heat-shrinkable fluororesin tube in the present invention, a copolymer tube such as perfluoroalkoxy resin (PFA) is suitable, and such a tube is
A primer is applied to the second insulating layer in advance, and the second insulating layer is fitted into a roller and then heated at a temperature at which the tube contracts to bond the tube to the roller surface. Then, after the tube is bonded, the roller is fired at a temperature not lower than the melting temperature of the fluororesin to obtain the heat fixing roller of the present invention.

(Operation) In the heat fixing roller of the present invention configured as described above, since the electric resistance heating element provided on the roller metal core shaft through the first insulating layer causes a current to directly generate heat on the surface, Good thermal efficiency and low power consumption.

In addition, since the heat-shrinkable fluororesin tube is adhered and fused to the outside of the second insulating layer provided on the electric resistance heating element, there is no pinhole or crack, and the fluorine film is smooth and has a uniform film thickness. A resin layer is obtained.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

The drawings schematically show a part of the cross section of an embodiment of the heat fixing roller of the present invention. As shown in the figure,
In the heat fixing roller of this embodiment, a first insulating layer 2 made of aluminum oxide, an electric resistance heating element 3, and an iron core shaft 1 are provided.
The second insulating layer 4 made of aluminum oxide is sequentially provided by plasma spraying. Further, after applying the primer 5 thereon, the PFA copolymer tube 6 was inserted and blown with hot air of 180 ° C. to shrink and adhere, and then baked at 380 ° C. to obtain the heat fixing roller of the present invention.

The obtained roller had a smooth fluororesin layer without pinholes or cracks on the surface.

[Advantages of the Invention] As described above, the heat fixing roller of the present invention has the heat generating layer near the roller surface, thereby reducing power consumption, shortening the waiting time at the start, and eliminating pinholes. A fluororesin layer with a smooth surface is easily provided,
Excellent heat fixing property.

[Brief description of the drawings]

The drawings schematically show a part of the cross section of an embodiment of the heat fixing roller of the present invention. 1 ... Metal core shaft 2 ... First aluminum oxide 3 ... Electric resistance heating element layer 4 ... Second aluminum oxide 5 ... Primer layer 6 ... PFA copolymer tube layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References Japanese Patent Laid-Open No. 63-78188 (JP, A) Actual Development Sho-56-130957 (JP, U)

Claims (1)

(57) [Claims] 1. A first insulating layer, an electric resistance heating element, a second insulating layer, and a heat-shrinkable fluororesin tube are bonded on a metal core shaft, and then at a temperature not lower than the melting temperature of the fluororesin. A heat fixing roller comprising a fluororesin layer formed by heating and fusing in order.