JPS63213880A - Fixing roll device - Google Patents

Abstract

PURPOSE:To obtain excellent releasability and durability and to prevent offset due to electrification by earthing the core part of a heat roll and forming a releasable resin coating part with a thermally contractible fluororesin tube containing conductive particles. CONSTITUTION:The core part 3 of a heat roll 1 is earthed and is covered with a thermally contractible fluororesin tube 4 containing conductive particles. Thus, the electric resistance in the tube 4 is reduced to prevent the electrification offset phenomenon due to electrostatic attraction of toner to the surface electric charge of the roll 1 at the time of paper passing. Further, the roll 1 has not the surface roughened by wear by using the thermally contractible fluororesin tube 4 and the durability of the roll 2 is improved, as well.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a standard roller device used in equipment using an electronic photocopying process, such as an electrophotographic copying machine, facsimile machine, and printer, and particularly relates to a roller device having a heating roller. The present invention relates to a heated fixing roller device.

[Prior Art] Conventionally, in a heat fixing device such as a copying machine using an electrophotographic process, when the unfixed glue on the copy paper melts and becomes sticky, a part of the fixing roller melts and becomes sticky. adheres to the surface of As a result, a so-called offset phenomenon occurs in which the image is transferred to the next copy sheet.

Methods for preventing this offset phenomenon include a method in which the toner contains a treatment substance that improves release properties, a method in which the surface of the heating roller is impregnated with a type III agent such as silicone oil, and a method in which the surface of the heating roller is impregnated with a type III agent such as silicone oil.
) A method of coating the surface of the heating port with a heat-resistant aiW# or a heat-resistant elastic material such as silicone rubber has been proposed and put into practical use.

However, in this type of conventional method, the silicone oil used for shrinking mold ~1 quickly runs out and the offset phenomenon cannot be prevented for a long time. When coated with an elastic material, the roller surface becomes extremely rough due to abrasion when the number of copies to be made exceeds the number of copies made, resulting in an offset phenomenon.

Therefore, in order to increase the durability of the roller, for example, tetrafluoroethylene-perfluoroargyl vinyl with excellent hardness is disclosed in 153563/1981, JP-A-61-32081, etc. Aether sympathic union (
It has been proposed to use a heat-shrinkable resin duplex such as PFA resin.

[Problem that R-mei aims to solve 1 However, even when using a heating roller covered with a highly durable heat-shrinkable fluororesin tube, an offset phenomenon occurs due to the charging caused by paper passing, and it is difficult to prevent the offset phenomenon. was found to be incomplete.

The present invention was devised in order to solve the above-mentioned problems, and an object of the present invention is to provide a fixing device that has excellent mold releasability and durability, and can reliably prevent offset due to charging. It is something to do.

[Means for Solving the Problems] The present invention provides a core having a heating means, and a conductive material containing a conductive material in the core. ! ! A heating roller having a polyurethane resin coating portion and a pressure roller that is in pressure contact with the heating roller is provided, and a copy sheet holding unfixed toner is placed so that the holding surface of the unfixed toner is in contact with the heating roller. In a fixing roller device that fixes the undetermined toner onto the copy paper by passing between a heating roller and the pressure roller, the core portion of the heating roller is grounded, and the releasable resin coating portion is It is characterized by being composed of a heat-shrinkable fluororesin tube containing conductive particles.

In the present invention, the core of the heating roller is grounded, and
By coating the outer periphery of this core with a heat-shrinkable fluororesin Chicove containing conductive particles such as carbon powder, the electrical resistance in the tube is reduced and the toner is absorbed by the static M m produced by adsorption
Electrical offset phenomenon can be prevented. The fixing device of the present invention is not only effective in preventing charging offset, but also eliminates the risk of the roller surface becoming rough due to abrasion due to the use of heat-shrinkable fluorine PA resin dupe, which was a problem in the past. This has the dual effect of significantly improving durability.

Note that when a heat-shrinkable fluororesin duplex is used as the f1 layer of the heat-fixing roller, it is generally considered that there is no particular need to provide a single layer of primer as an adhesive.

In other words, by directly coating the outer periphery of the core of the roller with dupe, it is technically possible to create a roller with an appropriate surface hardness due to the inherent hardness of the tube, and since an additional layer of primer is not required, it is possible to manufacture the roller accordingly. It can also be expected to have the practical effect of saving the above effort.

[Example] Each example of the present invention will be described below along with one comparative example.

(Comparative Example) An example of a conventional type fixing roller device is shown in FIG. 4 as a schematic cross-sectional view. The heating roller 100 has a heater 101 serving as a heating means as a grounded core inside.
Core metal 102 made of metal such as aluminum or aluminum alloy
For example, one layer of solution type primer 10.3 containing fluororesin, which is commercially available as an adhesive undercoat.
and a heat-shrinkable tube 104 made of tetrafluoroethylene-perfluoroalkyl vinyl ether co-polymerized composite (PFA resin) coated on the outer periphery of the brimer FF103.
It is composed of.

A pressure roller 105 is in pressure contact with this heating roller 100,
The unfixed toner T is removed from the copy paper P by passing the copy paper P containing the unfixed toner through the pressure contact part of the roller 100 so that the toner holding surface of the copy paper P is in contact with the heating roller 100.
to fix it. In the figure, 106 is a guide plate for the copy paper P.

Regarding the fixing roller device with the above configuration, the type of copy paper was changed, 38 sheets were fed, and the band was determined by a surface electrometer. ! ! We measured the electric current and evaluated the offset performance.

The ranking of offset performance is as follows: ○: No offset △: Hardly understood ×: Uriku offset 1 - XX=offset only for patternXXXX: Indicates offset up to characters. As a result, as a copy paper, Nekosa 8η×11.7
When using 5g/mt, the charging potential is -80 to -400
v, and the offset performance was XX×, that is, the offset occurred up to the characters, and there was no offset prevention effect. Next, copy paper to Neusittler A4, 80o/
As a result of changing to RL and testing, Obi N? ! ! The rank is -100
-280V, and the offset performance was XX, that is, only the pattern had offset, and although it was slightly improved, it was still poor.

(First Example) A schematic sectional view of a first example of the present invention is shown in FIG. In this embodiment, the heating roller 1 is equipped with a heater 2 as a heating means.
A core metal 3 (having the same material and structure as the conventional example), which is a grounded core having a Remberflu Aroaltruvinyl ether copolymer (P
The heat shrink tube 4 was made of a FAFA resin tube with 3% of carbon powder, which is a 1# conductive element, added thereto.

The method of mixing carbon into the PFA tube 4 is as follows:
This was done by mixing and dispersing carbon powder into the A-tube material in a molten state. Pressure welding row 5
105 used a roller having the same structure as the conventional device of the comparative example. In the figure, 1 is a portion of unfixed toner, and P is a copy paper passed along the guide plate 106 through the pressure contact portion of the rollers 1 and 105.

Regarding the fixing roller device having the above configuration, the paper charging characteristics and offset performance were evaluated as W1 under the same conditions as in the comparative example. As a result, when Nekosa (trade name) was used as copy paper, the charging potential was -80 to -240V, and the offset performance was ×,
In other words, there was only a slight tingling offset. Next, when Noizi 1-Lar (trade name) was used as copying paper, band 74N was -60 to -105V, and the offset performance was △, that is, it was barely noticeable.

It was confirmed that the offset performance was improved by about one rank compared to the conventional example.

(Second Embodiment) FIG. 2 shows a schematic sectional view of a second embodiment of the present invention. In this embodiment, the heating row 55 includes a grounded core bar 3 (having the same material and structure as the conventional example) and a core bar 3 (having the same material and structure as the conventional example) which has heaters 2 therein as heating means, and an outer circumference of the core bar 3. An intermediate layer 6 which is a conductive adhesive is coated, and integrally with this intermediate layer 116, a polytetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) is coated as a releasable resin coating part.
A heat-shrinkable resin tube 7 made of a mixture of a resin tube and 3% carbon powder was joined to the core bar 3. The intermediate layer 6 is a conductive and adhesive portion made of a fluororesin (polyamideimide) and carbon powder added thereto as a conductive material.

Pressure contact [1-The roller 105 used the same structure as the comparative example and the first example.

Regarding the fixing roller device having the above configuration, the conductive intermediate layer 6
As a result of measuring the charging characteristics and performance of OffCera 1 by changing the amount of carbon, which is the conductive material inside, it was found that when the carbon content is 1 wt%, the charging potential is O~-140■, and OffCera 1-
The performance was Δ~01, that is, there was almost no offset, which was significantly improved compared to the above comparative example.

Next, when the amount of carbon was increased to 3 wt% and measurements were taken, the charging potential showed +10 to -80V, the offset performance was O, and offset current no longer occurred.

Compared to the conventional example, it was found that both charging characteristics and offset performance were significantly improved.

(Third Embodiment) A schematic sectional view of a third embodiment of the present invention is shown in FIG. In this embodiment, the heating roller 8 is connected to a heater 2 as a heating means.
A core metal 3 (having the same material and structure as the conventional example) is a grounded core having a core inside, and an intermediate layer 9 made of a conductive adhesive is coated on the outer periphery of the core metal 3. Fi
9, a tetrafluoroethylene-perfluorofurkyl vinyl ether copolymer (
A heat-shrinkable resin Chico 110, which is a combination of 3% carbon powder and 3% carbon powder, is bonded to the core 3.The intermediate layer 9 is made of a fluororesin dispersion (PFΔ dispersion) with carbon powder as an IP electrical material. This is the added conductive and adhesive part.

Pressure contact [1-Ra 105 used a roller having the same structure as the comparative example, the first example, and the second example.

With respect to the fixing roller device having the above configuration, the charging characteristics of the heating roller and A) cutting performance were measured by changing the carbon field in the conductive intermediate layer 9. As a result, the carbon content was approximately 1wt%.
In the case of , the band m potential was 0 to -100V, the offset performance was Δ to O, and almost no offset phenomenon occurred. Further, when the amount of carbon was 3 wt%, the charging potential was -3 to -70V, the offset performance was O, and no offset occurred. When the amount of carbon was further increased to 5 wt%, the charging potential was O to -40V, the offset performance was O, and no off-hit was observed.

In this example, the best test binding of 1g was obtained not only in the conventional example as a comparative example but also in the first and second practical examples.

[Effects of the Invention] According to the fixing roller device of the present invention, conductive particles, such as carbon powder, are added to a heat-shrinkable fluororesin duplex having poor durability as the grounded core of the heating roller. By bonding the core directly or integrally with a conductive adhesive containing conductive particles such as carbon, it is possible to maintain excellent durability on the roller surface. At the same time, by adding conductive particles such as carbon powder to the mold releasability 4@fat coating and by grounding the core, the electrical resistance in the coating can be reduced, preventing the occurrence of charging offset from being a practical hindrance. It has the effect of reducing it to a minimum.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of the first embodiment of the present invention;
The figure is a schematic I9i side view of the second embodiment of the present invention, and the third
The figure is a schematic sectional view of a third embodiment of the present invention. FIG. 4 is a schematic sectional view of a conventional device as a comparative example. 1.5.8... Heating roller 2... Heater (heating means) 3... Core bar (core part) 4.7.10... Carbon-containing heat-shrinkable PF tube 1-b (conductive heat-shrinkable fluororesin tube containing particles)・
(Release resin coating part) 6.9... Intermediate l1l (conductor IR+1 adhesive) 105
... Pressure roller 106 ... Guide plate P ... Copy paper T ... Unfixed toner Patent applicant Minolta Camera Co., Ltd. Figure 1

Claims (3)

[Claims] (1) A heating roller having a core portion having a heating means, a releasable resin coating portion containing a conductive substance on the core portion, and a pressure roller that presses against the heating roller, and removes unfixed toner. A fixing roller device that fixes the unfixed toner onto the copy paper by passing the copy paper held between the heating roller and the pressure roller so that the surface holding the unfixed toner contacts the heating roller, A fixing roller device, wherein the core portion of the heating roller is grounded, and the releasable resin coating portion is made of a heat-shrinkable fluororesin tube containing conductive particles. (2) The fixing roller device according to claim 1, wherein the heat-shrinkable fluororesin tube is integrally joined to the core portion with a conductive adhesive. (3) The fixing roller device according to claim 1, wherein the conductive particles are carbon powder.