JPH01173085A - Fixing device - Google Patents

Abstract

PURPOSE:To extend the service life until a fixing roller becomes unuseable due to an offset by cleaning the fixing roller by a fibrous cleaning member containing a polishing grain. CONSTITUTION:A recording material 13 which has carried an unfixed toner image 12 is allowed to pass through between a fixing roller 1 and a pressure roller 4. By a halogen heater 7 controlled to a prescribed temperature, the toner image 12 is fixed onto the recording material 13. In this process, the unfixed toner image 12 which is brought to thermal fixation onto the recording material 13 is offset little by little onto the roller 1, and it is eliminated as follows, by a cleaning device 24. That is, a web 18 is formed by plating heat resistance nonwoven cloth with nickel by an electroless plating method, and it is fibrous, therefore, pressed by a pressure roller 16, and brings the roller 1 to cleaning, while being wound up by a winding roller 17. In such a way, an effect for wiping off a toner becomes high, and the service life of the roller 1 can be extended.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is an image forming apparatus such as a copying machine, a laser beam printer, a magnetic stylus printer, etc., in which an unfixed image is formed on a recording material using a roller. The present invention relates to a fixing device that is used in the field of fixing technology, and particularly includes a cleaning device for cleaning a fixing roller for thermal fixing using a heat roll fixing method.

(Prior Art) In an image forming apparatus such as an electrostatic recording device, an unfixed image formed on a recording material (for example, paper or an OHP sheet) is transferred onto the recording material as a final finishing step of the image forming process. It is necessary to make it firmly established. A fixing device for this purpose generally uses a heat roll fixing method.

As shown in FIG. 7, a heat roll fixing device in a conventional electrophotographic apparatus that has a fixing process coats the outer layer of an aluminum core 2 with silicone rubber 3 to a predetermined thickness. A fixing roller 1 consisting of a metal core 5 made of aluminum, a pressure roller 4 consisting of a core metal 5 whose outer layer is coated with silicone rubber 6 to a predetermined thickness, and a resin coating 6' on its surface layer;
The fixing roller 1 includes a heat source 7 disposed within the fixing roller 1 and the pressure roller 4, and the like.

According to the fixing device configured as described above, the recording material 13 carrying the unfixed toner image 12 is conveyed between the fixing roller l and the pressure roller 4 by a conveying means (not shown), and the recording material 13 carrying the unfixed toner image 12 is conveyed between the fixing roller l and the pressure roller 4. As a result, the unfixed toner image 12 is heated and fixed onto the recording material 13. At this time, a small amount of toner forming the unfixed toner image 12 on the recording material 13 is transferred to the fixing roller l.
transfer, or offset, to the surface of Since the toner offset to the fixing roller l may deteriorate the quality of electrophotographic images, electrophotographic apparatuses are equipped with a cleaning device for cleaning the surface of the fixing roller l. There are various kinds of leaning devices like this.

As shown in FIG. 7, the above-mentioned conventional cleaning device is designed to contact a web 15 made of a fibrous member (for example, Nomex (trade name), etc.) and clean the fixing roller l with the fibrous member. (Refer to Japanese Unexamined Patent Application Publication No. 50-57237).

(Problems to be Solved by the Invention) However, especially in a heat roll fixing type fixing device, when the surface of the fixing roller 1 becomes rough and the gI type property deteriorates, the surface of the fixing roller 1 becomes rough. The adhesion with the toner becomes high, and the toner comes to adhere to the surface of the fixing roller l. Therefore, there is a problem in that the web 15 may not be able to completely remove the toner on the fixing roller 1 from the roller.

Furthermore, as another conventional cleaning device, there is one in which a sand vapor is brought into contact with the fixing roller l instead of the fibrous member 15 shown in FIG. 7, and the fixing roller l is cleaned by the sand vapor ( Japanese Patent Application Publication No. 5
1-5023), such sandpaper grinds the toner on the surface of the fixing roller 1, so it is more effective in removing toner from the fixing roller 1 than the aforementioned fibrous member. becomes larger. However, since the surface of sandpaper has a low affinity for toner, it has poor toner adsorption ability and low ability to carry away toner.For this reason, toner tends to accumulate in the contact area between the fixing roller l and the sandpaper, and cleaning There is a problem of decreased ability.

The present invention has been made in view of the above circumstances, and its purpose is to improve the ability to remove the developer present on the surface of the roller used for fixing unfixed images from the surface of the roller. Another object of the present invention is to provide a fixing device equipped with a cleaning device capable of improving the ability to collect the removed developer, thereby improving the ability to clean the developer on the roller.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a fixing device having a roller for fixing an unfixed image.
The present invention is characterized by comprising a cleaning device that contacts the roller and cleans the roller with a fibrous cleaning member containing abrasive particles at least on the side that contacts the roller.

(Function) In this way, the developer offset to the roller for fixing the unfixed image is adsorbed between the fibers of the fibrous cleaning member, preventing the toner accumulation layer from becoming high in some places. Therefore, the surface of the roller and the cleaning member are always kept in contact with each other. Furthermore, the abrasive particles contained in the m fibers of the cleaning member act as an abrasive on the roller surface and scrape off the developer offset on the roller surface, thereby further increasing the cleaning ability of the cleaning device.

(Example) Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a configuration diagram of a fixing device according to the present invention, and in the figure, l denotes a fixing roller, which has LTV silicone rubber (low-temperature vulcanization type silicone rubber) 3 on the outer layer of an aluminum core 2. It is formed by coating to a predetermined thickness. A pressure roller 4 is provided below the fixing roller l, which is coated with HTV silicone rubber 6 to a predetermined thickness on the outer layer of an aluminum core 5, and further coats the surface layer with HTV silicone rubber 6. It is formed by applying a resin coating 6'.

Further, a halogen heater 7 serving as a heat source is disposed within the fixing roller 1 and the pressure roller 4. A thermistor 8 is brought into contact with the pressure roller 4, and the thermistor 8 controls whether the supply of current to the halogen heater 7 is on or off. In this way, the fixing roller
and the temperature of the pressure roller 4 are maintained at a predetermined temperature (for example, 170" C) suitable for fixing the unfixed toner image on the recording material 13 onto the recording material 13. , these fixing roller 1 and pressure roller 4 are rotated in the direction of the arrow in the figure by a drive device (not shown).

On the other hand, in order to improve the releasability of the toner from the fixing roller 1, a release agent application device 9 is provided at a predetermined location of the fixing device. This release agent application device 9 is configured to apply silicone oil lO in an oil tank to the fixing roller l via a felt 11.

Furthermore, a cleaning device 24 for cleaning toner offset on the fixing roller l is provided at a predetermined location of the fixing device. This cleaning device 24 includes a nickel-plated web 18 that is a fibrous cleaning member that is brought into contact with the fixing roller l by a pressing roller 16.
This is to clean the fixing roller l. This nickel-plated web 18 is made by plating a conventional heat-resistant nonwoven fabric Nomex (trade name) with nickel by an electroless plating method, and the surface of the fibers of the web 18 is coated with nickel to a thickness of about a few coats.

The nickel-plated web 18 configured in this manner is fed by the feed roller 14 in the direction of arrow C in the figure and is wound up by the take-up roller 17.

Next, the operation of the fixing device configured as described above will be explained.

The recording material 13 carrying the unfixed toner image 12 is conveyed by an unillustrated device in the direction of arrow a in FIG. The recording material 13 is heated to a predetermined temperature by heat passed between the fixing roller l and the pressure roller 4 and supplied from the halogen heater 7 via the fixing roller l and the pressure roller 4, respectively.
The unfixed toner image 12 carried thereon is fixed onto the recording material 13.

In the above-mentioned thermal fixing process, the unfixed toner image 12 that is thermally fixed onto the recording material 13 is offset little by little to the fixing roller 1, or the offset toner is removed from the fixing roller l by the cleaning device fi24 as follows. removed.

That is, the nickel-plated web 18 is moved to the take-up roller 17 at a predetermined speed (while being pressed by the pressure roller 16
It is wound up at a rate of 1 mm per 100 sheets of recording material. Then, the nickel plated web 18 is attached to the fixing roller l.
As it rotates, it is rubbed against the surface of the fixing roller 1, and the surface of the fixing roller 1 is cleaned.

In this case, since the nickel-plated web 18 is fibrous, it has good contact with the fixing roller 1, unlike a smooth and hard cleaning member such as a metal roller. That is,
As shown in FIG. 2, the toner 23 that is offset in some places on the surface of the fixing roller l is adsorbed between the fibers #22 of the web 18, so that the toner does not accumulate in some areas and the fixing roller The contact condition between L and the nickel plated web 18 is improved. Since the web 18 is fibrous, it is highly effective in wiping away the toner from the fixing roller 1.

In addition, the nickel contained in the side of the nickel-plated web 18 that contacts the fixing port roller l adsorbs the toner on the fixing roller l well, since metals such as nickel have a high affinity with toner. As a result, the cleaning power of the cleaning device 24 to remove toner from the fixing roller l is significantly improved compared to the conventional web. Therefore,
Since the alffiability of the surface of the fixing roller 1 is reduced, toner becomes strongly adhered to the surface of the fixing roller 1, but such toner can also be easily removed.

Furthermore, when the nickel-plated web 18 is rubbed against the surface of the fixing roller l, the fibers of the nickel-plated web 18! 1
The nickel attached to the fibers 22 is appropriately removed, and the nickel particles 24' remain between the fibers 22 (see Figure 2).
In this way, the nickel particles 24' falling off the fibers 4922 and staying between the fibers 22 act as an abrasive on the surface of the fixing roller 1, and scrape off the toner offset on the surface of the fixing roller 1. Since the nickel particles 24' are metal, the metal abrasive particles roll on the surface of the fixing roller l between the fibers 22 due to their high affinity with the toner, and are scraped off from the surface of the metal particles and the fixing roller l. The applied toner is strongly adsorbed. Therefore, if the surface of the fixing roller l is made of rubber such as silicone rubber or fluorine rubber, offset toner may enter the surface layer of the rubber, but the surface layer of the rubber will be scraped due to the abrasive effect of the metal particles mentioned above. Therefore, the offset toner is reliably separated from the fixing roller l. Then, the toner 23 that has been cleaned and collected is attached to the fibers of the web 18 as shown in FIG. It is adsorbed between I22 and carried away.

Therefore, toner does not accumulate in the contact area between the fixing roller 1 and the web 18, and the surface layer of the fixing roller 1 is always kept clean, improving the cleaning ability of the cleaning device 14.

Further, since the fibers of the nickel-plated web 18 are coated with nickel, the abrasive effect is higher than that of conventional webs, and furthermore, since the fibers are coated with metal, the adsorption of toner is increased. These properties are combined, that is, the toner on the surface of the fixing roller 1 is ground, adsorbed, and collected by the nickel web 18, and effective cleaning is performed.

As described above, the life of the fixing roller l until it becomes unusable due to toner offset can be significantly improved compared to the conventional method.

According to durability tests, conventional web-based cleaning devices could only fix 80,000 sheets before the fixing roller became unusable due to offset.
In the cleaning device of the present invention using a nickel-plated web, the number of sheets that could be fixed reached 200,000 sheets, and the service life of the fixing roller could be significantly extended.

Further, the cleaning device for a fixing device according to the present invention is particularly effective in a fixing device in a color image forming apparatus. The fixing device shown in FIG. 1 is particularly effective in the fixing step in color image formation, and various toners of yellow, magenta, cyan, and black are laminated on the recording material 13 in multiple layers. In this type of color image formation, in order to reproduce colors close to those of the original document, multiple layers of toner are heated and melted to mix the colors. Is it necessary to use toner? Since it is necessary to have a low melting point, it is not possible to mix in a large amount of wax that improves the releasability of the toner. This is due to the high melting point of wax. In this case, the sharp melt toner is likely to be offset by the fixing roller L, and the toner layer to be fixed is thick due to the stacking of multiple colors, so it is easy to offset. However, each toner is slightly different due to environmental fluctuations, etc., so toner offset is more likely to occur in a fixing device that performs constant temperature control.

For this reason, the surface material of the fixing roller used in color image formation is particularly limited, and from the viewpoint of release properties, a fluorine resin layer such as Teflon (trade name), which is conventionally used in black and white image fixing devices, is Since it is difficult to use other materials, silicone rubber or silicone resin as shown in FIG. 1 is used. Furthermore, among silicone rubbers, RTV (room temperature vulcanizable silicone rubber) is particularly preferred. This is because fluororesin is not compatible with mold release agents such as silicone oil that prevent offset. Therefore, the surface layer of the roller is preferably made of silicone that is active against silicone oil, and is particularly preferably impregnated with oil.

In such a combination of sharp melt toner and fixing roller l made of silicone rubber, the adhesion between the sharp melt toner and the silicone rubber is not very high, and the toner melted by heat penetrates into the silicone rubber, causing fixation. This changes the quality of the rubber surface layer of the roller 1, thereby degrading the releasability of the fixing roller 1.

The present invention is particularly effective in the fixing device of the color image forming apparatus described above.

When we conducted a durability test using the fixing device shown in Figure 1, we found that the number of sheets that could be fixed was 8,000 before the fixing roller became unbalanced due to offset in the conventional cleaning device using a web made of Nomex. On the other hand, in the cleaning device of the present invention using a nickel-plated web, the number of sheets fixed reached 50,000 sheets, and the life of the fixing roller was significantly extended.

The color toner used in color image formation will be described below.

Color toners are 1. For example, polyester resin, styrene.
Acrylic resin 1 Colorant (dye, sublimable dye), charge control agent, etc. are melted, mixed, crushed, and classified to produce toner. If necessary, an external addition step of adding various external additives to the toner may be added.

The average particle size of the toner is usually 5 to 30 JLm. In consideration of offset resistance, fixing properties, and sharp melt properties, it is particularly preferable that the color toner uses a polyester resin as a binder resin.

A sharp-melt polyester resin is a high molecular compound having an ester bond in the main chain of a molecule synthesized from a diol compound and a dicarboxylic acid.

Examples of diol components include ethylene glycol,
l, 2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butynediol, 1,4-bis(hydroxymethyl)cyclohexane, bisphenol A, hydrogenated bisphenol A , polyoxyethylenated bisphenol A, polyoxypropylenated bisphenol A
Examples include bisphenol type diols such as.

Examples of the dicarboxylic acid component include aliphatic dicarboxylic acids or aromatic dicarboxylic acids such as maleic acid, fumaric acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, cohelic acid, adipic acid, sepacic acid, malonic acid, and oxalic acid; Examples thereof include acid anhydrides or esters with lower alcohols.

The softening point of the sharp melt polyester resin used in the present invention is 60 to 150°C, preferably 80 to 120°C.
C is good. In addition, the polyester resin has a weight average molecular weight (Mw) of 4,000 to 200,000, preferably 4,
000 to 100.000, number average molecular weight (Mn)
is 2,500 to 7,000, preferably 3,000 to 5
．． 000 (provided that Mw≧Mn) is preferable. Furthermore, M w / M n of polyester resin
is preferably 7 or less (more preferably 6 or less), that is, it is below the specified range of each average molecular weight. The M w of polyester resin becomes too high and cannot be put to practical use.
/Mn is 7 or more, no sharp melt is exhibited and color mixing becomes insufficient.

The softening point in the present invention is the temperature T measured by the method below. refers to the value subjected to measurement. Note that the measurement method according to the present invention may be considered and modified.

That is, using a flow tester CFT-500 type (manufactured by Shimadzu Corporation), with a tie (nozzle) diameter of 0.5 mm and thickness of 1.0 mm, an extrusion load of 50 kg was applied, the initial temperature was set at 80°C, and the preheating time was 300. 2 seconds later, a plunger drop amount-temperature curve (hereinafter referred to as a softening S-curve) of the toner drawn when the temperature is raised at a constant rate of 5° C./minute is determined. The sample toner used is 1 to 3 g of purified fine powder, and the plunger cross-sectional area is 1.0 cm2.

The softening S-shaped curve normally becomes a curve as shown in FIG. 6. As the temperature rises at a constant rate of 0, the toner is gradually heated and begins to flow out (plunger descends from A to B). If the temperature is further increased, the molten toner will flow out significantly B→
C-+D>, the plunger stops descending and ends.
([)→E).

The height H of the S-curve indicates the total outflow, and the temperature T corresponds to the 0 point of H/2. indicates the softening point of the toner.

The sharp melt resin in the present invention means T+=100 to 150, where T is the temperature at which the melt viscosity shows 10'cp, and T2 is the temperature at which the melt viscosity shows 5XIO'cp.
"c IΔTI=IT+Tzl=5~30'C
Refers to a resin that satisfies the following conditions.

In addition, melt viscosity measurement can be carried out using a constant temperature bath in which the temperature of the sample and rotor can be adjusted (for example, Viscon-H
A rotor N is attached to a B-type rotational viscometer for high viscosity (e.g., model BBH, manufactured by Tokyo Keiki Co., Ltd.) equipped with a model I model VC-250 manufactured by Toyo Seisakusho Co., Ltd.

This can be done using No. 4 or No. 5.

Sharp-melt resins having these temperature-melt viscosity characteristics are characterized by an extremely sharp decrease in viscosity when heated. This reduction in viscosity causes proper mixing of the uppermost toner layer and the lowermost toner layer, and also rapidly increases the transparency of the toner layer itself, resulting in good subtractive color mixing.

For example, toners using resins of T1 or less than 100'C easily cause blocking and have shortcomings in storage stability.

Furthermore, if T1 is higher than 150°C, the color mixing property will be poor and the fixing property will also be difficult.

In addition, materials used as binder resins of toners can be appropriately mixed as arbitrary acid components.0 For example, styrene-alkaline acid ester copolymer, styrene-methacrylic acid ester copolymer, polyvinyl chloride, Natural resin-modified phenol.

Natural resin modified maleic acid resin, polyvinyl acetate, silicone resin, polyurethane, polyamide resin, ionomer resin, furan resin, epoxy resin, xylene resin,
Polyvinyl butyral, terpene resin, coumaron indene resin, petroleum resin, chlorinated paraffin, etc. can be used as appropriate.

Coloring agents used in toner include carbon black, nigrosine dye, lamp black, and sudan black SM.
, First Yellow 〇, Benzidine Yellow, Picment Yellow, India First Orange, Irgazine Red, Valanitroaniline Red, Toluidine Ret, Carmine FB, Permanent Bordeaux FR
R, Pigment Orange R, Resole Red 2G,
Lake Lett C, Rhodamine FB, Rhodamine B Lake, Methyl Violet B Lake, Phthalocyanine Blue, Picment Blue, Turrillant Green B,
Phthalocyanine Green, Oil Yellow GG, Zapon First Yellow CGG, Kayaset Y963, Kayaset YG, Sumiblast, Yellow G, Zapon First Orange RR, Oil Scarlet, Sumifrust Orange G, Orazole Fraun B, Pomelo First Scarlet CG, Eisensviron Red B
EH, oil pink OP, etc.

By the way, as a second modified embodiment of the present invention, as shown in FIG. 3, a heat-resistant nonwoven fabric made of Nomex (trade name) is used.
Cerium oxide particles (average particle size 3uLm) are placed between the ik fibers 26.
) 25 dispersed therein, the cerium oxide particles 25 between the fibers 26 acted as an abrasive on the roller surface, similar to the nickel metal oxide particles in the first embodiment, and You can get the same effect as if In addition, in FIG. 3, 23 indicates the collected toner.

Another modified embodiment of the present invention will be described with reference to FIGS. 4 and 5.

FIG. 4 is a block diagram of a modified embodiment of the fixing device according to the present invention. In the figure, reference numeral 19 denotes a cleaning roller covered with a nickel-plated web similar to the nickel-plated web 18 in the first embodiment. The cleaning roller 19 is a cylindrical roller 2 made of aluminum as shown in FIG.
0, a nickel-plated web 2 constructed in the same manner as the nickel-plated web 18 in the first embodiment
1 is adhesively wound.

The cleaning roller 19 is rotated in the direction of arrow d in the figure by a drive device (not shown). Further, the other configurations are the same as those of the first embodiment described above.

According to the modified embodiment described above, the cleaning roller 19
As the fixing roller 1 rotates, the nickel-plated fibers 21 on the surface of the fixing roller 1 are rubbed against the surface of the fixing roller 1, thereby cleaning the surface of the fixing roller 1. The cleaning roller 19 rotates at a predetermined circumferential speed (for example, l mm per 100 sheets of recording material).

In this way, this modified embodiment also provides the same effects as the first embodiment described above. That is, the nickel-plated fibers 21 rubbed by the rotation of the fixing roller l are
The nickel adhering to the surface of the nonwoven fabric falls off moderately and stays as nickel particles between the nonwoven fabric fibers, and these nickel particles act as an abrasive on the surface of the fixing roller 1, so the toner offset on the surface of the fixing roller 1. is scraped off and collected in the nickel-plated fiber fa21, thereby further enhancing the cleaning effect. In addition,
When we actually conducted a durability test on this modified example, we found that
A cleaning effect similar to that of the first example was obtained.

In each of the above-mentioned embodiments, a nickel-plated web in which a web made of Nomex is plated with nickel is used as a cleaning member, but the present invention is not limited to this; It is also possible to use a plated plate. When a durability test was conducted on a fixing device equipped with a cleaning device using such a cleaning member for a copper-plated web, the same effects as in the case of a nickel-plated web were obtained. However, once used for cleaning, the cleaning power will decrease the next time due to nickel falling from the fibers and adsorption of toner to the nickel, so do not reuse the part as a cleaning member as shown in Figure 1. Preferably disposable.

In addition, the method for manufacturing a nickel-plated web by plating Nomex with nickel is not limited to the electroless plating method described above, but other methods may also be used, and furthermore, it is not limited to the plating method. A metal coating may be applied to the web using a thermal spray molding method or the like. In addition, it goes without saying that aluminum, copper, etc. can be used as metals contained in the fibers, and silicone rubber,
If you use sharp melt toner as toner,
Experimentally, nickel was found to be the most suitable.

(Effects of the Invention) As explained above, according to the present invention, in a fixing device having a roller for fixing an unfixed image, the abrasive particles are in contact with the roller and at least on the side that contacts the roller. Since the roller is equipped with a cleaning device that cleans the roller using a fibrous cleaning member, it is possible to increase the ability to wipe off the developer on the surface of the roller and improve the ability to collect the wiped developer. As a result, the ability to clean the developer on the fixing roller can be improved, and the life of the fixing roller before it becomes unusable due to offset can be extended.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a fixing device according to the present invention, FIG. 2 is a diagram showing the adsorption state of toner between am and a of a nickel-plated web, and FIG. 4 is a diagram showing the state of toner adsorption, FIG. 4 is a configuration diagram of a modified embodiment of the present invention, FIG. 5 is a perspective view of a cleaning pipe covered with a nickel-plated web, and FIG. 6 is a graph showing a softening curve of a flow tester. , FIG. 7 is a block diagram of a conventional fixing device. l...Fixing roller, 4...Pressure roller, 12...
Unfixed toner image, 13-...Transfer material (recording material), 18°21...Nickel-plated web (cleaning member)
, 19...Cleaning roller, 24-...Cleaning device. Patent Applicant Canon Co., Ltd.

Claims (4)

[Claims] (1) In a fixing device having a roller for fixing an unfixed image, cleaning of the roller with a fibrous cleaning member that contacts the roller and contains abrasive particles at least on the side that contacts the roller. A fixing device characterized by comprising a device. (2) The fixing device according to claim 1, wherein the layer of the roller that comes into contact with the unfixed image is an elastic body made of silicone rubber. (3) The fixing device according to claim 1, wherein the fixing device fixes a plurality of developers having different compositions onto the recording material at once. (4) The fixing device according to claim 3, wherein the plurality of developers having different compositions form a layered structure.