JP2000338810A - Heat fixing roll - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a heat fixing roll which is improved in the electrical conduction and heat conduction from a cylindrical body arbor to a releaser layer surface and is improved in the release characteristic of the releaser layer while maintaining the smoothness and wear resistance of the releaser layer surface. SOLUTION: The releaser layer 3 of the heat fixing roll 10 successively having a primer layer 2 consisting essentially of a fluororesin formed to a thickness of 1/5 to 1/10 the surface roughness Rz on the surface of the cylindrical body arbor 1 and the releaser layer 3 consisting essentially of the fluororesin on the surface of the cylindrical body arbor 1 subjected to surface roughening is formed to have conductive carbon black 4 uniformly dispersed therein at 2 to 4 wt.% of the total weight of the releaser layer and the surface of the releaser layer 3 is smoothed. The surface of the cylindrical body arbor 1 is roughened by sandblasting to the surface roughness 4 to 15 μmRz. The releaser layer 3 is smoothed by pressing of, for example, a metal roller thereto.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrophotographic copying machine,
The present invention relates to a heat fixing roll used in office equipment such as a laser printer and a facsimile.

[0002]

2. Description of the Related Art Conventionally, in office equipment such as an electrophotographic copying machine, a laser printer, and a facsimile, the transfer paper is sandwiched and conveyed by two rolls of a heat fixing roll and a pressure roll while an unfixed paper on the transfer paper is not fixed. Unfixed toner on transfer paper has been fixed by heating and melting the toner and bringing the toner into close contact with the transfer paper.

[0003] As such a heat-fixing roll, there is known a heat-fixing roll in which a release layer is formed on the surface of a cylindrical core, and a heater such as a halogen heater is installed along a substantially central axis of the cylindrical core. Have been. In such a heat fixing roll,
Heat from the heater is transferred to the release layer on the roll surface via the cylindrical core, and the unfixed toner is fixed on the transfer paper.In recent years, as a measure to save energy in office equipment, the thickness of the core has been reduced. Attempts have been made to make the heater thinner and to shorten the energizing time to a heater such as a halogen heater.

[0004] Such a heat-fixing roll is manufactured through, for example, the following steps. (A) A drum-shaped cylindrical metal core made by cutting and grinding the surface of a cylindrical body made of a metal such as aluminum alloy or iron-based metal, so that the outer diameter of both ends of the cylindrical body is larger than that of the central part. And (B) The surface of the cylindrical core is sandblasted, etched,
Rough by means such as liquid honing. Roughening the surface of the cylindrical core in this way is because the fluororesin used for the release layer has non-adhesive properties, but is difficult to adhere to, so that the fluororesin enters the core metal surface. This is for giving the anchor effect. (C) A primer having a fluororesin as a main component is applied to the surface of the roughened metal core, and the primer is air-dried or dried.
Drying is performed in an atmosphere of 0 to 150 ° C. to form a primer layer. (D) Apply a fluororesin paint on the primer layer. Perfluoroalkoxy resin (hereinafter, referred to as fluororesin paint)
It is called "PFA". ) Tetrafluoroethylene resin (hereinafter, referred to as
It is called "PTFE". ) Is used, but if it is PFA, the form can be applied as a powder, so that PFA can be collected and reused. The fluororesin paint applied on the primer layer in this way is left for 20 to 40 minutes in an atmosphere at or above the melting point of the fluororesin, and is baked to form a release layer composed of a fluororesin coating.

In a conventional heat-fixing roll, carbon, graphite, and the like are added to a fluororesin paint for forming a release layer.
Additives such as metal oxides are added. When such an additive was added to the fluororesin paint, abrasion of the fluororesin coating caused by the separation claw contacting the heat fixing roll and the use of a positively charged toner were performed to separate the transfer paper contacting the heat fixing roll. The offset that occurs in the case is prevented.

Further, in a conventional heat fixing roll,
By adding a metal or metal oxide whisker to the fluororesin paint forming the primer layer, and adding conductive silicon carbide whiskers to the fluororesin paint forming the release layer, the thermal conductivity of the heat fixing roll is improved. It has been improved (JP-A-2-11578).

Further, in the conventional heat fixing roll, since the surface film of the release layer of the fired heat fixing roll is rough, the toner particles held on the transfer paper cannot be satisfactorily fixed. , It is not possible to obtain good quality images. Therefore, the surface of the release layer of such a heat fixing roll is polished to make the surface as smooth as possible.

[0008]

In the prior art,
As a means for shortening the thermal conductivity to the surface of the release layer of the heat fixing roll, a method of adding ceramics such as metal oxide and silicon carbide to the fluororesin of the primer layer and the release layer has been adopted. When a large amount of ceramics is added to the fluororesin, the melt viscosity of the fluororesin significantly increases, so that the surface roughness of the release layer after firing becomes rough. For this reason, there is a problem that the surface of the release layer must be cut more than necessary by polishing.

In recent years, in office equipment such as an electrophotographic copying machine, a laser printer, and a facsimile, high-quality images have been developed and fine toner has been used.
As shown in the prior art, when the surface of the release layer is polished,
The phenomenon that the toner adheres to the surface of the release layer occurs due to the fine toner entering the grooves of the polished eyes and interposing the paper dust generated from the transfer paper. Therefore, the surface of the release layer is cleaned or silicon oil is applied to the surface of the release layer so that the transfer paper can be released smoothly. However, since the toner wiped off from the heat-fixing roll accumulates on the cleaning member, and the toner re-transfers to the heat-fixing roll to generate an offset, the release layer of the heat-fixing roll is polished and then subjected to a polishing process. The surface of the release layer is remelted to remove the polishing line.However, if the surface of the release layer is remelted, the abrasion resistance of the fluororesin coating constituting the release layer is reduced, and However, there is a problem that the adhesiveness of the resin decreases.

An object of the present invention is to solve such a problem. That is, the present invention improves the electrical and thermal conduction from the cylindrical core to the surface of the release layer while maintaining the smoothness and wear resistance of the surface of the release layer. An object of the present invention is to provide a heat-fixing roll having improved properties.

[0011]

That is, in order to achieve the above object, the invention according to claim 1 provides a roughened surface of a cylindrical metal core on the surface of the roughened cylindrical metal core. A heat-fixing roll sequentially comprising a primer layer mainly composed of a fluororesin having a thickness of 1/5 to 1/10 with respect to Rz, and a release layer mainly composed of a fluororesin, A heat-fixing method, wherein the release layer has 2 to 4% by weight, based on the total weight thereof, of the conductive carbon black dispersed uniformly, and the surface of the release layer is smoothed. Roll.

According to a second aspect of the present invention, in the first aspect of the present invention, the surface of the cylindrical metal core is roughened to a surface roughness of 4 to 15 μmRz by sandblasting. It is.

According to a third aspect of the present invention, in the first or second aspect, the surface of the release layer is smoothed by pressing a metal roller. .

[0014]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an enlarged sectional view of a main part of a heat fixing roll according to an embodiment of the present invention.

The heat-fixing roll 10 of the present invention is arranged such that the surface of the roughened cylindrical core 1 is applied to the surface roughness Rz (10-point average roughness) of the surface of the cylindrical core 1 by one. / 5 to 1/1
A primer layer 2 mainly composed of a fluororesin having a thickness of 0 and a release layer 3 mainly composed of a fluororesin, and the release layer 3 has a total weight of On the other hand, it has 2 to 4% by weight of the conductive carbon black 4 dispersed uniformly, and the surface of the release layer 3 is smoothed.

The surface of the cylindrical core 1 is preferably
The surface is roughened to 4 to 15 μm Rz by sandblasting. The surface of the release layer 3 is preferably smoothed by pressing a metal roller.

In the present invention, the cylindrical metal core 1 is made of a metal such as an aluminum alloy or an iron-based metal. Preferably, the surface of the cylindrical metal core 1 is cut and ground.
The outer diameter of both ends of the cylindrical metal core 1 is made larger than that of the central part in a drum shape.

The surface of the cylindrical metal core 1 is sandblasted,
The surface is roughened by means such as etching and liquid honing. In FIG. 1, 1a is a mountain and 1
b is a valley. Examples of the fluororesin used for the primer layer 2 and the release layer 3 include PFA and PTFE.
Is used.

The primer layer 2 is formed by, for example, spray-coating a primer mainly composed of a fluororesin. At this time, the surface roughness Rz
The coating is performed so as to have a thickness of 1/5 to 1/10 of (10 points average roughness). Thus, the surface roughness Rz (10-point average roughness) of the surface of the cylindrical cored metal 1 is 1/5 to 5
When coated so as to have a thickness of 1/10, a structure is obtained in which the peaks 1 a on the surface of the cylindrical cored bar 1 are exposed from the primer layer 2. When the conductive release layer 3 in which the conductive carbon black 4 is dispersed is formed on the primer layer 2, the peaks 1 a bite into the release layer 3 so that the release layer 3 is separated from the cylindrical core 1. The electric conduction and heat conduction to the three surfaces are improved, so that the ridges 1a of the cylindrical core 1 have the ground effect of the cylindrical core 1 and the heat release effect.

The primer layer 2 enters the valley 1b on the surface of the cylindrical metal core 1 roughened by sandblasting or the like.
The adhesion with the release layer 3 is maintained. PT among fluororesins
Since FE has a high melt viscosity, even if PTFE is melted and cooled to form a film, the PTFE particles are less likely to flow and become a film. Therefore, when PTFE is used for the release layer 3, a binder is required. Must be used, and a primer layer 2 is required. When PFA is used for the release layer 3,
Since PFA has thermal fluidity, the primer layer 2
A film can be formed following the shape of the metal core 1.

The fluorocarbon resin constituting the release layer 3 preferably contains 2 to 4% by weight of conductive carbon black 4 uniformly dispersed therein, based on the total weight of the fluorocarbon resin. . When the conductive carbon black 4 is added to the fluororesin constituting the release layer 3 as described above, the electric resistance of the release layer 3 is reduced and the wear resistance of the release layer 3 is improved. When the release layer to which the conductive carbon black 4 is added is pressed with a metal roller, the surface thereof becomes smooth, and the releasability is improved. When the amount of the conductive carbon black 4 is less than 2% by weight, the electric resistance of the release layer 3 increases, and when the amount exceeds 4% by weight,
Since the melt viscosity of the fluororesin film increases, the surface roughness increases, and even when pressed with a metal roller, the surface does not become smooth.

[0022]

(Example 1) The outer diameter of both ends of an aluminum pipe was made larger than that of the center part, and the surface of a drum-shaped cylindrical core was roughened to 8 µmRz by sandblasting. A fluororesin (MP902BN, manufactured by DuPont Mitsui) was applied to the surface of the cylindrical metal core roughened to 8 μm Rz by spray coating to a thickness of 1 μm so that the sandblasted surface was exposed to form a primer layer. On this primer layer, a fluororesin: PFA (MP102, manufactured by DuPont-Mitsui) to which 3% by weight of conductive carbon black (Ketjen Black, manufactured by LionAcd) was added, and the resultant was baked. A 15 μm release layer was formed. Then, while holding and rotating both ends of the core metal, a metal roller (SUS304, 40 mm in diameter) is pressed against the surface of the release layer with a pressing pressure of 0.3 Mpa to finish the surface of the release layer smoothly and heat A fixing roll was used. The film thickness, surface roughness, film electrical properties and pencil hardness of the heat fixing roll thus obtained were measured, and the heat fixing roll was mounted on a copying machine (Spirio3200, manufactured by Ricoh Co., Ltd.) for continuous copying. The surface temperature of the heat-fixing roll at the time, the toner fixation in intermittent copying, the presence or absence of occurrence of an offset image, and the number of durable sheets were measured. The measurement results are shown in Table 1 below.

[0023]

[Table 1]

(Comparative Example 1) The surface of a cylindrical core metal similar to that in Example 1 was sandblasted to 8 μm in the same manner as in Example 1.
It was roughened to Rz. Fluororesin (MP902BN, manufactured by DuPont-Mitsui Co., Ltd.) is applied to the surface of the cylindrical metal core roughened to 8 μm Rz by 5 μm so that the peak of the sandblast surface is exposed.
m was applied by spray coating to form a primer layer. On this primer layer, silicon carbide whiskers 3
Fluororesin to which weight% is added: PFA (MP102, manufactured by DuPont Mitsui) is applied and baked to a thickness of 15 μm.
m release layers were formed. Then, the surface of the release layer was polished by sandblasting to finish it flat, and a heat fixing roll was obtained. The film thickness, surface roughness, film electrical properties and pencil hardness of the heat fixing roll thus obtained were measured, and the heat fixing roll was mounted on a copying machine (Spirio3200, manufactured by Ricoh Co., Ltd.) for continuous copying. The surface temperature of the heat-fixing roll at the time, the toner adhesion during intermittent copying, the presence or absence of occurrence of an offset image, and the number of durable sheets were measured. The measurement results are shown in Table 2 below.

[0025]

[Table 2]

As can be seen from Tables 1 and 2, Example 1
In Comparative Example 1 and Comparative Example 1, the characteristics were better in Example 1, the temperature drop during continuous copying with a copying machine was smaller in Example, and heat conduction from the halogen heater was better. .

The advantages of the present invention are as follows. (A) According to the present invention, the surface of the roughened cylindrical metal core is １ ／ of the surface roughness Rz of the surface of the cylindrical metal core.
Since a primer layer mainly composed of a fluororesin having a thickness of about 1/10 and a release layer mainly composed of a fluororesin are sequentially provided, the peaks on the surface of the cylindrical metal core are primers. The structure is exposed from the layer. For that purpose,
The conductive carbon black on the primer layer penetrates into the conductive release layer in which the conductive carbon black is dispersed, improving the electrical and thermal conduction from the cylindrical core to the release layer surface, and the grounding effect of the cylindrical core. And a heat release effect.

(B) According to the present invention, 2 to 2 parts of the fluororesin constituting the release layer, based on the total weight of the fluororesin,
Since 4% by weight of the conductive carbon black uniformly dispersed is added, the electric resistance of the release layer is reduced and the wear resistance of the release layer is improved.

(C) When the release layer to which the conductive carbon black is added is pressed with, for example, a metal roller, the surface becomes smooth, and the release property of the release layer is improved.

[0030]

According to the heat-fixing roll of the present invention, the electric conduction and the heat conduction from the cylindrical core to the surface of the release layer are improved while maintaining the smoothness and wear resistance of the surface of the release layer. A heat-fixing roll having a good releasing property of a releasing layer is provided.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a main part of a heat fixing roll according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylindrical core metal 1a Peak part 1b Valley part 2 Primer layer 3 Release layer 4 Conductive carbon black 10 Heat fixing roll

Claims (3)

[Claims] 1. A primer containing a fluororesin as a main component and having a thickness of 1/5 to 1/10 with respect to the surface roughness Rz of the surface of the roughened cylindrical core. Layers and
And a release layer having a fluororesin as a main component.
A heat-fixing roll comprising about 4% by weight of conductive carbon black dispersed uniformly, and wherein the surface of the release layer is smoothed. 2. The heat fixing roll according to claim 1, wherein the surface of the cylindrical core metal is roughened by sandblasting to a surface roughness of 4 to 15 μmRz. 3. The heat fixing roll according to claim 1, wherein the surface of the release layer is smoothed by pressing a metal roller.