JPS582864A - Heat fixing roller - Google Patents

Abstract

PURPOSE:To accelerate the fixation of copying paper and to obtain long-period use by using a heat fixing roller constituted by covering the external surface of a metallic roller used for an electronic copying machine, etc., with a rubber sheet which consists essentially of fluororubber and also contains fluororesin. CONSTITUTION:An aqueous dispersed solution obtained mixed 95wt% fluororubber and 5wt% fluororesin (ethylene tetrafluoride resin) together is used, and a vulcanizing agent is added to and mixed with the solution, which is applied over the surface of an aluminum roller by spraying and then dried. This is heated at 300 deg.C to obtain a heat fixing roller with 30mum coating thickness. Then, 5-70% fluororesin based upon the total weight is added to obtain the best property balance between the antitackiness and wear resistance. When the coating thickness is 10-100mum, the heat fixing roller has the highest thermal efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fixing device for electronic copying machines, facsimile machines, and the like.

2. Description of the Related Art In electrostatic type electronic copying machines and the like, the method most commonly used these days for fixing a toner image formed on a sheet of paper is to use a heating roller. This fixing method is a method in which paper on which a toner image is formed is passed between two rollers pressed together, and one or both of the rollers is heated from the inside to fuse the toner image onto the paper.

This fixing method has many advantages over other open fixing methods, such as high thermal efficiency and easy speedup, and it is rarely used in modern electronic copying machines. A fixing method using a roller is used. Usually, the fixing roller is made of metal such as stainless steel or aluminum and its surface is coated with a non-adhesive substance such as fluorine resin or silicone rubber to prevent offset.

Recently, rollers coated with fluoroplastics such as tetrafluoroethylene resin (hereinafter abbreviated as PTFE resin) or tetrafluoroethylene bar-70 alkyl vinyl ether copolymer (hereinafter abbreviated as PFA resin) are used as heating fixing rollers in many electronic applications. Used in copying machines.

However, in the case of a heat fixing roller coated with such a fluorocarbon resin, there is a problem that the abrasion resistance or scratch resistance is insufficient.

In other words, the heat fixing roller has a peeling tab to peel the paper off the roller, a blade or felt to clean the roller surface, and a thermistor to detect the roller surface temperature, all of which are in constant contact with the roller. The fluorocarbon resin is worn out or damaged by these, and is also worn down by the toner and paper that pass between the support roller and the fixing roller. As a result, after long-term use, the underlying metal is exposed and the fixing roller cannot be used as a fixing roller. The problem was that it could no longer function properly.

The present inventor completed the present invention as a result of intensive studies to solve this problem.

Generally, one way to improve such abrasion and scratch resistance is to make the coating layer as hard as possible. In order to harden the coating layer of fluorocarbon resin, silicone rubber, etc., it is necessary to include various fillers, but this method improves the hardness, but the non-adhesiveness is greatly reduced, and the fixing roller However, it is not possible to simultaneously satisfy non-adhesive properties and abrasion resistance.

On the other hand, as a method for improving wear resistance and scratch resistance, the coating layer is provided with rubber elasticity to provide a buffering effect, thereby improving the wear and scratch resistance.

Regarding this method, a roller was invented in which a silicone rubber was made to contain a tetrafluoroethylene resin (Bitoku Koko Sho 5l-27384), but this method had relatively good wear resistance and scratch resistance. However, it was not sufficient as a fixing roller in terms of non-adhesion and durability.6 The present invention provides a coating layer with rubber elasticity to create a fixing roller with the best abrasion resistance, scratch resistance, and non-adhesion. This is what we provide.

A feature of the present invention is that the coating layer is made of fluorocarbon rubber and contains fluorocarbon resin.

Fluorubber is a rubber made from vinylidene fluoride, propylene hexafluoride, ethylene tetrafluoride, etc., and is highly heat resistant and durable. Examples of the fluorocarbon resin include tetrafluoroethylene polymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and the like.

The mixing ratio of fluoro rubber and fluoro resin is 9 in terms of weight ratio.
It is preferable that 5=5 to 30 near G.

If the amount of fluorine rubber is less than this, the rubber-like elasticity of the roller coating layer will be lost, and when used as a fixing roller, it will be more likely to be scratched by a peeling nail or the like.

Furthermore, if the amount of fluorine rubber is more than this, the non-adhesiveness will be low and offset will easily occur, causing a practical problem.

The fluorocarbon resin used here needs to have a continuous usable temperature of about 200°C or higher, which is necessary for the fixing roller, so tetrafluoroethylene resin and tetrafluoroethylene-perfluoroalkoxyethylene resin are used. A polymer (hereinafter abbreviated as PFA resin) or tetrafluoroethylene-hexafluoropropylene resin (hereinafter abbreviated as FEP resin) is desirable, and among these, PFA resin is particularly preferred.

The reason for this is that PFA has greater heat resistance than FEP resin,
Also, compared to tetrafluoroethylene resin, it has almost the same non-adhesive properties and heat resistance, but when used as a fixing roller, it is less likely to be scratched and has a long life as a roller. It has characteristics.

Therefore, PFA is most preferable as the fluororesin to be mixed with the fluorocarbon rubber.

Further, the thickness of the coating is preferably 15 μm or more and 100 μm or less. If the thickness is less than 15 μm, the effect of elasticity is less likely to be exerted due to the influence of the base metal, and the effect of preventing damage caused by a peeling nail or the like is reduced.

Moreover, if it is 100μ or more, thermal conductivity deteriorates, and it takes longer for the heat of the internal heater to reach the surface, resulting in poor thermal efficiency.

Next, such a mixture of fluoro rubber and fluoro resin has extremely superior adhesion to the underlying metal compared to fluoro resin alone or silicone rubber, and especially in the case of fluoro resin or silicone rubber, it has excellent adhesion to the metal base. There is no need for any primer treatment.

Even when the base is roughened by blasting or the like, sufficient adhesion can be achieved with a roughness of 10 μm or less. Therefore, in order to make the coated surface as smooth as possible, the roughness of the base surface should be 1.
It is preferable to set the roughness to 0 μ or less (10-point average roughness defined by JISB-0601).

Next, a method of manufacturing such a fixing roller will be described. The metal roller serving as the base material is sufficiently degreased by a known method, and then subjected to surface roughening treatment such as blasting, if necessary. In this case, the surface after blasting should be 10 μm as much as possible.
It is preferable that the roughness is as follows.

Next, the fluorocarbon resin and the fluorocarbon rubber are generally mixed and stirred in the form of a dispersion, solution, or powder, respectively. need to be added. Further, pigments and the like may be added if necessary. When the mixture is in liquid form, the coating method is spray painting, brushing, etc.

After coating, volatile components such as solvents were evaporated, and further 300
Crosslink the rubber at temperatures below °C.

Furthermore, surface polishing or the like may be performed as necessary.

Next, examples of the present invention will be described.

Example 1 The surface of an aluminum roller was roughened by sandblasting. The roughness of the aluminum roller surface at this time was 10
The point average roughness was 5μ.

On this surface, a vulcanizing agent was added to an aqueous dispersion prepared by mixing tetrafluoroethylene resin and fluorocarbon rubber in the ratio shown in Table 1, mixed, and this was applied by spraying and air-dried. The coating thickness at this time was 30μ. This was heated at 300'C for 15 minutes to produce a heat fixing roller of the present invention.

For comparison, a roller made of fluorocarbon rubber alone, a roller made of tetrafluoroethylene resin alone, and a roller made of a mixture of tetrafluoroethylene resin and silicone rubber at a ratio of 1:1 were prototyped.

These rollers were set in the fixing section of a copying machine, and the toner image on the paper was fixed at a roller surface temperature of 180° C., and the occurrence of offset was observed. Then, the cases where the offset clearly occurred are marked (×), and the cases where no offset occurred at all (O
), and those that slightly occurred were designated as (Δ).

In addition, PPS separation claws were brought into contact with these rollers at a pressure of 100 f and rotated at 180° C. for 10 hours, and the depth of scratches at this contact portion was measured. These results are shown in Table 1 below.

10- Example 2 The surface of a stainless steel roller was grease-selected with Triclean, and an aqueous dispersion containing 50% by weight of PFA resin and 50% by weight of fluorocarbon rubber was applied to the surface to a thickness of 40 μm.
It was dried at 0°C and further heated at 280°C for 15 minutes.

When this roller was evaluated in the same manner as in Example 1, no offset occurred, and the depth of scratches caused by the separation claws was 1 μm or less.

By using a mixture of fluorine rubber and fluorine resin in this manner, a heat fixing roller that has excellent non-adhesive properties and is almost free from scratches can be obtained.

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Claims (5)

[Claims] (1) In a heat fixing roller in which a coating layer is provided on the outer surface of a metal roller to prevent offset, the coating layer is mainly composed of fluorine rubber and fluorine resin, and the total amount of fluorine resin is 596%. (weight) to 7096 (weight) containing 7 resins, and its thickness is 15μ
A heating fixing roller characterized by having a thickness of ~100μ.
□ (2) Claim 1, characterized in that the fluorocarbon resin is a tetrafluoroethylene resin, a tetrafluoroethylene-bar70 alkoxyethylene copolymer, or a tetrafluoroethylene-hexafluoropropylene copolymer. Heated fixing roller. (3) The heating fixing roller according to claim 1, wherein the coating layer has a structure in which the fluorine resin content is large in the surface layer and small in the interior of the coating layer. (4) The heat fixing roller according to claim 3, wherein the fluorocarbon resin is a tetrafluoroethylene-perfluoroalkoxyethylene copolymer. (5) The surface roughness of the base metal is JIS average roughness.
The heating fixing roller according to claim 1, characterized in that the 10-point average roughness shown in B-0601 is not more than lθμ.