JPH0113633B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heating roll device used for fixing, etc. in electrophotographic copying machines and the like.

[Conventional technology]

An electrophotographic copying machine is equipped with a photosensitive drum having a photoconductor surface layer, and the outer circumferential surface of the photosensitive drum is uniformly charged, and then the outer circumferential surface is exposed to light through the image of the object to be copied. Copying has come to be performed by forming an electrostatic latent image on the outer peripheral surface, attaching toner to this electrostatic latent image to form a toner image, transferring this to copy paper, etc., and then fixing it. There is. The fixing of the toner is usually carried out by heating and fixing the copy paper onto which the toner image has been transferred by passing it between a heating roll and a pressure roll.
As shown in FIG. 3, this type of heating roll is generally constructed by forming a planar heating element layer 3 on the outer peripheral surface of a hollow cylindrical core metal 1 with an insulating layer 2 interposed therebetween. The insulating layer 2 is made of an inorganic electrical insulating material such as glass or mica, or an organic polymer electrical insulating material, and the planar heating element 3 is made of silicone with a conductive filler such as carbon black. It is composed of heat-resistant conductive rubber added to rubber.

[Problem that the invention seeks to solve]

However, in the conventional heating roll apparatus as described above, when forming the insulating layer 2, no matter which inorganic electrical insulating material or organic electrical insulating material is used, a sufficient thickness of insulation cannot be achieved in one treatment. Because the film could not be formed or pinholes were generated in the insulating film, several treatments were required, making the manufacturing process complicated.

An object of the present invention is to provide a heating roll device that can simplify the manufacturing process.

[Means for solving problems]

In order to achieve the above object, the heating roll device of the present invention includes an aluminum hollow shaft core and an alumite electrical insulation film formed on the outer peripheral surface by oxidation of the outer peripheral surface of the aluminum hollow shaft core. layer, and a planar heating element layer formed on the outer peripheral surface of the aluminum hollow shaft core with the alumite electrical insulation layer interposed therebetween.

That is, the heating roll device described above uses an aluminum core, and forms an alumite electrical insulating layer by oxidizing the outer peripheral surface of the core, and uses this in place of the conventional insulating layer. This eliminates the need for complicated operations such as multiple treatments of inorganic and organic insulating materials, and simplifies manufacturing.
Furthermore, the alumite electrical insulating layer also provides an effect of improving dielectric breakdown voltage.

As described above, the heating roll device of the present invention forms an alumite electrical insulating layer on the outer peripheral surface of the aluminum hollow shaft core by oxidizing aluminum,
This is used in place of the conventional insulating layer, and this is its greatest feature.

The outer circumferential surface of the aluminum hollow shaft core can be inspected by conventionally known anodic oxidation. This anodic oxidation creates a porous surface (pore diameter of approximately 330 Å) on the outer peripheral surface of the aluminum hollow shaft core.
An anodized electrically insulating layer is formed. The alumite electrical insulating layer formed in this way has a uniform layer thickness and has high electrical insulation properties, but the heating roll device of this invention constantly maintains a temperature of about 200°C. Since the alumite electrical insulating layer is heated, it is necessary to take into account the occurrence of cracks in the alumite electrical insulating layer due to the difference in thermal expansion coefficient between the alumite electrical insulating layer formed as described above and the aluminum base metal underneath. The above-mentioned alumite electrical insulating layer formed by anodizing has hexagonal columnar cells as its constituent elements, and the center of each cell has a hole as described above.
Pores with a pore diameter of approximately 330 Å are formed. Although these pores have a negative effect on electrical insulation, they bring about good results in terms of preventing the occurrence of cracks.

Taking these into consideration, the inventor conducted a series of studies and found that by setting the thickness of the alumite electrical insulating layer within the range of 5 to 20 μm, the requirements for both electrical insulation and cracking can be met. I found out. The most desirable layer thickness is 10 μm.
Note that at this time, the pores of the alumite electrical insulating layer need to be maintained in their original state without being blocked. Further, the layer thickness and the like of the alumite electrical insulating layer can be measured using an electron micrograph.

The planar heating element layer can be formed by disposing a conventionally known planar heating element layer on the alumite electrical insulating layer formed as described above. In this case, it is acceptable to form a planar heating element layer directly on the alumite electrical insulation layer, but an insulating organic polymer adhesive such as an epoxy adhesive may be used to utilize the adhesive strength of this adhesive. It is preferable to form it by doing so. By using an insulating organic polymer adhesive in this way, an organic polymer insulation layer is formed between the planar heating element layer and the aluminum base metal, and the two insulation layers prevent dielectric breakdown. A significant voltage improvement effect can be obtained. Although the thickness of the organic polymer insulating layer is not particularly limited, it is preferable to set the layer thickness to about 30 to 200 μm in terms of the insulation effect.

Such a heating roll device with two electrically insulating layers can be used, for example, with only an anodized electrically insulating layer.
It can withstand a dielectric breakdown voltage of 520V and approximately 1000V including the organic polymer insulation layer.

Next, the present invention will be explained in detail based on examples.

〔Example〕

1 and 2 show one embodiment of the invention. In these figures, reference numeral 11 denotes an aluminum hollow shaft core, and an alumite electrical insulating layer 12 is formed on the outer peripheral surface of the shaft core body 11 by anodizing the outer peripheral portion thereof. 13 is an organic polymer insulating layer made of an epoxy resin adhesive formed on the alumite electrical insulating layer 12, and 14 is a planar heating element layer. This planar heating element layer 14 is made of heat-resistant conductive rubber obtained by adding carbon black to silicone rubber and setting the volume resistivity to 10° to ^{10 3} Ω·cm. Note that the planar heating element layer 14 is energized through a conventionally known energizing section and a power feeding section (not shown).

A heating roll device having such a structure is manufactured by anodizing the outer periphery of the aluminum hollow shaft core 11 and further forming two insulating layers 12 and 13 by applying an epoxy resin adhesive. This eliminates the need for multiple treatments of organic/inorganic electrical insulating materials as in the past, and simplifies the manufacturing process. Moreover, the two insulating layers 12 and 13
Due to the action of , the dielectric breakdown voltage also exceeded 1000V, which is a significant improvement.

In the above embodiment, the planar heating element layer 14 is made of silicone rubber, but instead of this,
A heat-resistant elastic layer is formed using a compound made by blending a predetermined amount of conductive carbon black and a crosslinking agent with a resin such as epoxy resin, polyimide resin, fluorine resin, or fluorine rubber. It's okay.

〔Effect of the invention〕

As described above, the heating roll device of the present invention has
An aluminum material is selected as the shaft core, and an alumite electrical insulating layer is formed on the outer circumference by oxidation, so the shape of the insulating layer does not require multiple treatments of electrically insulating materials as in conventional methods. , it becomes possible to greatly simplify the manufacturing process. especially,
When an organic polymer insulating layer made of an epoxy resin adhesive or the like is provided between the aluminum base metal of the aluminum core body and the alumite electrical insulating layer, the insulating layer becomes two layers, and the breakdown voltage is significantly improved. effect will be obtained.

[Brief explanation of drawings]

FIG. 1 is an overall perspective view of an embodiment of the present invention, FIG. 2 is an enlarged sectional view of the main part thereof, and FIG. 3 is a sectional view of a conventional example. 11... Aluminum hollow shaft core body, 12...
Alumite electrical insulating layer, 13...organic polymer insulating layer, 14... planar heating element layer.

Claims (1)

[Scope of Claims] 1. An aluminum hollow shaft core, an alumite electrical insulating layer formed in the form of a film on the outer peripheral surface of the aluminum hollow shaft core by oxidation of the outer peripheral surface of the aluminum hollow shaft core, and the aluminum hollow shaft core. A heating roll device comprising a planar heating element layer formed on the outer peripheral surface of the body with the alumite electrical insulation layer interposed therebetween. 2. The heating roll device according to claim 1, wherein an organic polymer insulating layer is interposed between the planar heating element layer and the alumite electrical insulating layer. 3. The heating roll device according to claim 1 or 2, wherein the layer thickness of the alumite electrical insulating layer is set within the range of 5 to 20 μm.