JPH0658578B2 - Fixing device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fixing device for fixing a recording material supporting a toner image, a latent image, or the like, or an object to be fixed such as a sheet requiring heating or heating / pressurizing.

[Prior art]

In a fixing device for a recording apparatus which has been widely used conventionally, a roller fixing of a heating / pressurizing method is mainly used.

The heating and pressure type roller fixing device is roughly classified into (1)
A system in which a so-called Teflon-coated roller such as PTFE or PFA is used as the fixing roller, and an elastic body-covered roller such as silicon rubber, fluororubber, EPDM, hydrin rubber, or fluorosilicone rubber is used as the pressure roller, or (2) fixing roller Both the pressure roller and the pressure roller are of the system using the above elastic body covered roller.
The street is known.

In the case of using the elastic covered roller of (2) as the fixing roller among the above (1) and (2), as compared with the case of using the Teflon covered roller, the fixing property, the image property, and the curl property (especially automatic It is especially useful for high-speed machines and system machines because it is effective for double-sided machines.

However, in the case of (2), the mold release property of the elastic body covered roller such as silicon rubber is inferior to that of the Teflon covered roller in view of long-term (including durability), and conventionally, this time-dependent In order to alleviate the deterioration of the releasability as much as possible, a large amount of offset preventing liquid such as dimethyl silicone oil having a relatively low viscosity is applied to the roller surface.

Therefore, it had the following problems.

Oil stains on copy paper (deterioration of copy quality) The fixing roller and / or the pressure roller swells unevenly with the offset prevention liquid, causing wrinkles on the copy paper and different fixing properties. The mechanical strength of the roller was lowered, and the roller was damaged, or the rubber layer and the core metal were peeled off from each other.

Further, in order to prevent the above, when a small amount of high-viscosity offset preventing liquid is applied, deterioration of releasability of the fixing roller becomes remarkable, and the toner is fused to the fixing roller or the copy paper is jammed. As a result, the fixing roller needs to be frequently replaced. Further, the above-mentioned deterioration of the releasability cannot be discriminated by the visual observation of the surface of the fixing roller (there is no adherence of toner or paper powder).

As described above, in the fixing device having both the fixing roller and the pressure roller having the elastic surface layer, the advantage of the elastic surface layer is not utilized.
On the other hand, many problems were involved, and it was uneconomical because the roller replacement period was short.

〔Purpose〕

An object of the present invention is to enable economical practical use of a fixing device having elastic surface layers for both the fixing roller and the pressure roller.

Another object of the present invention is to obtain stable fixability even at high speed processing, to extremely prevent the occurrence of jams and toner offsets, to maintain their preventive effect for a long period of time, and to prevent image crushing and image periphery. It is an object of the present invention to provide a fixing device capable of minimizing the scattering of toner.

[Basic Theory of the Present Invention]

The present inventor has analyzed the cause of the problem of the conventional elastic roller pair, and has reached the following conclusion.

That is, when the fixing roller having the elastic surface layer gradually decreases in diameter due to long-term use, the releasability is good, but this period is short, and when the diameter decrease almost disappears, It was clarified that the separation of materials became unstable and the toner offset increased rapidly.

That is, the above problem is equivalent to the problem of how to stabilize the diameter reduction of the elastic surface layer over a long period of time.
Further, since the conventional diameter reduction tends to decrease sharply in the initial stage, it is also an important issue to reduce the initial change.

Further, the present inventor has found that the reduction of the diameter is mainly due to the reduction of the low molecular weight oil component (referred to as the low molecular weight releasing agent) in the elastic surface layer as follows.
It was found that there is a point, and the main cause was solved and the present invention was achieved.

1. Volatilization in air by heating 1. Transition to recording materials 3. Transfer to pressure roller Of these, 1 is development that occurs in heat fixing,
If the roller temperature is set to 200 ° C. or lower, it can be made extremely small, and it is completely irrelevant in pressure fixing. Further, 2 is important for separation of the recording material and prevention of toner offset, and it is preferable to make an appropriate amount, and in the case of a roller pair having an elastic surface layer, it is considerably smaller than 3. Therefore, the main cause is "Transition to pressure roller" of 3.

In order to solve the cause of 3, it is necessary to suppress 3 as much as possible while generating 2 in an appropriate amount, and the release agent holding force of the fixing roller on the toner image side is changed to the release release force of the pressure roller. Given by making it larger than. The present invention focuses on the filler contained in the elastic surface layer in order to obtain this holding force with a simple structure. The elastic surface layer of the fixing roller is separated from the filler contained in the elastic layer of the pressure roller. Mold adsorption force (oil absorption force)
Containing a large filler.

By virtue of this feature, the present invention can put the roller pair fixing having an elastic surface layer into practical use, and can provide an economical fixing device having good releasability over a long period of time.

[Explanation of Examples]

 Hereinafter, the details of the present invention will be described with reference to examples.

The figure shows that the toner image T formed by the electrophotographic method is fixed on the plain paper P by the heat fixing device.

A fixing roller 1 has a heater 3 for heating such as a halogen heater therein, and receives a driving force from a driving motor (not shown) to rotate in a direction of an arrow and comes into contact with the toner image T. A pressure roller 2 is pressed against the fixing roller 1 to rotate by being rubbed or driven.

In this fixing roller 1, a heat-resistant elastic layer 11 made of silicone rubber or the like is relatively thin (0.1 to 1 m) on the outer peripheral surface of a metallic hollow roller core 12 made of aluminum, stainless steel, copper or the like.
m) It is provided. The pressure roller 2 is rotatably supported by a bearing (not shown). This roller 2 holds the lever 13, the connecting portion 10 and the shaft 23 of the pressure roller which are rotated around the shaft 15 by a known pressing means (an eccentric cam 8 having a central shaft 16) on the fixing roller 1. This embodiment is composed of an arm 9 which rotates around the center of the roller 9 and at least a pressure contact at the time of fixing (in order to reduce the contact between the rollers 1 and 2 in this example, it is separated at a time other than a necessary time such as a fixing time or a heating time). Be done). The pressure roller 2 includes a metal roller core 22.
The elastic layer 21 made of silicon rubber, fluorine rubber, fluorosilicone rubber or the like is relatively thick (for example, 5 mm to 10 mm) on the outer peripheral surface of the
The degree is provided.

A temperature sensitive element 4 such as a thermistor or a thermocouple is disposed in contact with the outer peripheral surface of the fixing roller 1, and a detection signal of the temperature sensitive element 4 is guided to a well-known control means 17 to determine the temperature of the outer peripheral surface of the fixing roller 1 (output of the heater 3). , Or by controlling the applied voltage, etc.) to hold the toner image at a set temperature of 200 ° C. or lower in order to fuse and fix the toner image. Denoted at 5 and 51 are separation claws for surely separating the copy paper after fixing from the rollers.

6 is a cleaning / application member for removing foreign matter such as offset toner and paper powder adhered to the surface of the fixing roller from the roller surface and applying an offset prevention liquid. Heat-resistant non-woven fabric such as Nomex or Himeron is applied to silicone oil or the like. The web 61 is used containing an offset prevention liquid.

The web 61 is brought into contact with the fixing roller by a pressing roller 63 having elasticity such as silicone rubber, fluorine rubber, fluorosilicone rubber, silicone rubber sponge. or,
This web 61 has a take-up roller 64 which is driven.
Thus, the supply roller 62 moves so as to slightly change its contact position, and the new surface of the web 61 always contacts the fixing roller.

The main fillers contained in the elastic layer 11 of the fixing roller 1 and the elastic layer 21 of the pressure roller 2 are dry silica in the elastic layer 11 on the side in contact with the toner image and in the elastic layer 21 on the pressure side. Wet silica was used.

Although dry silica and wet silica will be described later, dry silica has a larger adsorption force (oil absorption in the case of oil) for retaining the release agent than wet silica.

In this way, since the consumption of the low molecular weight releasable component contained in the elastic layer 11 of the fixing roller 1 is reduced and stabilized by utilizing the magnitude relationship of the releasing agent adsorption force, in this embodiment, the release from the outside is eliminated. A fixing device having a good releasability was obtained for a long period of time even if the mold agent was not supplied or only a very small amount of the mold release agent was applied. The period during which the fixing roller 1 can be used is improved by about 2 to 7 times as compared with the conventional fixing rubber roller, and it is possible to provide an economical and excellent fixing property for a long period of time.

Next, a specific range of the blending ratio of the filler will be shown. The dry silica powder contained in the elastic layer 11 is preferably 3% by weight or more and 25% by weight or less with respect to the rubber 100. This is because if the amount is less than 3% by weight, the dry silica does not have sufficient strength as a fixing roller and another filler is required. If the amount is more than 25% by weight, the releasability of the roller is deteriorated and the offset is caused. In addition to inducing swelling and jamming, the viscosity of the rubber becomes too high during kneading, which makes manufacturing difficult. Of course, these are numerical examples in the case of using only dry silica as the main filler, and the range is actually effective in the present invention, but it may change to some extent when other fillers are used in combination. Similarly, when wet silica is contained in the elastic layer 21, it is 20 per 100 rubber.
It is necessary that the amount is not less than 35% by weight, preferably not less than 35% by weight.

The amount of the filler contained in these elastic layers 11 and 12 is
It is preferable that the number of the fixing roller 1 is smaller than that of the pressure roller 2 in order to improve the releasability, and the inclusion of wet silica in the pressure roller 2 can reduce the charging of the pressure roller itself. Since the toner offset due to the electrostatic force can be significantly reduced, this example is particularly effective in that the toner offset can be totally reduced.

Further, the preferable range of the particle size and specific surface area of silica is such that, in consideration of the further improvement of the releasing agent adsorption force and the strength as the roller for the fixing device, the useful main dry silica has a primary particle size of 5 mμ to 60 mμ. Within range or specific surface area of 100m
² / ^g~380m are those in the range of ² / g, also primary particle diameter as the predominant wet silica is in the range of 10mμ~5μ or,
Specific surface area is within the range of 8m ² / g~300m ² / g is good.

Hereinafter, the effects and the like will be described with reference to specific numerical examples of the fixing roller 1 and the pressure roller 2.

First, as the fixing roller 1, the following having a 0.5 mm thick elastic surface layer 11 of HTV silicone rubber was manufactured.

Commercially available dry silica fine powder as a filler for unvulcanized silicone rubber, trade name of Nippon Aerosil Co., Ltd .: AE
ROSIL 380 was mixed with 10 parts by weight of 100 parts by weight of unvulcanized rubber and sufficiently kneaded with a vulcanizing agent to obtain an unvulcanized rubber sheet.

The unvulcanized rubber sheet was left standing at room temperature for 3 days. Outer diameter of the central part is 58.4mm and both ends are 100μ from 58.4mm
A large 7 mm-thick aluminum (A50J6) core metal was plasted, coated with an adhesive, and allowed to stand in a 25 ° C. environment for 5 hours, and then baked at 120 ° C. for 20 minutes.

The core metal is coated with the unvulcanized rubber sheet, and the pressure is set to 150.
Primary vulcanization was performed for 30 minutes at a temperature of 170 ° C. at kg / cm ² . (Using a press vulcanizer) Furthermore, after secondary vulcanization at 200 ° C for 4 hours, the outer diameter was 59.3
ground to mm. Then, the roll was dipped in 180 ° C. dimethyl silicone oil (having a viscosity of 100 cs at 25 ° C.) for 8 hours to be swollen, and then the outer diameter was 59.4 mm.
(Specifically, both ends are formed into an inverted crown shape having a size larger than 59.4 mm by 100 μ), and thus the fixing roller 1 is obtained.

Next, as the pressure roller 2, the following having a 5 mm thick HTV silicone rubber elastic surface layer 21 was manufactured.

As a filler for unvulcanized silicone rubber, 35 parts by weight of Nipseal, a commercially available wet silica fine powder manufactured by Nippon Silica Co., Ltd., is mixed with 100 parts by weight of unvulcanized rubber and vulcanized. It was sufficiently kneaded with the agent to give an unvulcanized rubber sheet.

The unvulcanized rubber sheet was left standing at room temperature for 3 days. A stainless steel (SUS 430) core metal having an outer diameter of 50 mm was blasted, coated with an adhesive, left for 5 hours in an environment of 25 ° C., and then baked at 120 ° C. for 20 minutes.

The core metal is coated with the unvulcanized rubber sheet, and the pressure is set to 150.
Primary vulcanization was performed for 30 minutes at a temperature of 170 ° C. at kg / cm ² . (Using a press vulcanizer) Furthermore, after secondary vulcanization at 200 ° C for 4 hours, the outer diameter was 59.5
ground to mm. Then, the roll was immersed in 180 ° C dimethyl silicone oil (having a viscosity of 100cs at 25 ° C) for 72 hours to be swollen, and then the outer diameter was 60 mm.
After finishing polishing, the pressure roller 2 was obtained.

Wherein is contained a viscosity 10,000cs at 25 ° C. of dimethyl silicone oil web 6 in ₁ (manufactured by Shin-Etsu Chemical Co. KF96),
It was applied to the surface of the fixing roller 1.

Then, the fixing roller speed is set to 445 mm / sec, the fixing roller surface temperature is set to 185 ° C., and the compression width of the roller pair is set to 8.5 mm, and the temperature is adjusted and pressurized.

The above examples are shown in Table 1 below, and in Comparative Examples 1, 2, and 3, fillers having the above-described roller structure were used as shown in Table 1 below.

Next, the results are summarized in Table 2. In Table 2, the initial oil amount of the fixing roller is 30% by weight with respect to 100 parts of rubber when the rubber equilibrium (saturation) swell is 10% of dry silica, and 22% with respect to 100 parts of rubber when 35% of wet silica. %, When the maximum content of silicone oil is 100%,
It is shown as a ratio to this.

The paper passing speed was 445 mm / sec, and the press contact width was 8.5 mm.

As can be seen from Tables 1 and 2 above, the fixing roller and the pressure roller have the same viscosity of the release agent contained therein, and the swelling degree of the release agent is almost the same. Therefore, the fixing roller of the example consumes less silicone oil as the release agent than any of the comparative examples 1, 2, and 3, and the life and durability are increased.

Specifically, the silicone oil consumption is 25% to 36% in the paper passing portion of the comparative example when 30,000 sheets are passed, whereas it is 9% in the paper passing portion of the embodiment, which is about 1%. It is recognized that it can withstand long-term use by reducing to 3-1 / 4.

After the paper as the recording material is forcibly continuously jammed between the fixing roller 1 and the pressure roller 2 (the oil consumption becomes large and the toner offset also increases), the offset toner is removed by cleaning. In terms of the number of sheets until it becomes a state where it cannot be cleaned, the durability of the example is improved by 3 to 10 times, and it has a powerful strength against a dangerous state and an accident. .

In addition, in the life test of the life by continuous paper feeding, the product of the example can realize the life extension of 2 to 10 times as compared with the comparative example.

As described above, in the embodiment of the present invention, there are many advantages over the conventional one, which makes a fixed image good, and offset prevention ability can be exerted over a long period of time, which is economical and simplifies the configuration.
It is possible to supply a small amount or no external supply of which offset has been prevented.

As the filler of the fixing roller, those having an excellent releasing agent adsorption force can be used, but it is preferably dry silica, which is a trade name of AEROSIL 130,200,300,380, manufactured by Nippon Aerosil Co., Ltd.
R972, TT600, MOX80, MOX170, COK84; CABOT brand name Cab-O-Sil M5, MS-7, MS-75, HS-5, EH-
5; WACKER-CHEMIE GMBH product name Wacker HDK N20, V15, N
20E, T30, T40; Dow Corning's trade name DC Finesilica; Fransil's trade name Fransol.

Further, as the filler for the pressure roller, for example, the following wet silica or other filler having a weak releasing agent adsorption force can be used. Specifically, a product name on the left and a manufacturer on the right are suitable.

Carpretx Shionogi Nipseal Nippon Silica Tokseal, Fineseal Tokuyama Soda Vita Seal Taki Taki Shiruton, Shirunetsuku Mizusawa Chemical Starsil Kamijima Kagaku Himesir Ehime Pharmaceutical Cyloid Fuji Debison Kagaku Hi-Sil Pittsburgh Plate Glass Co. (High Seal) (Pittsburgh Plate Glass Duro) Douro Seal) Fiillstoff-Gesellsc
haft Marquart Ultrasil Manosil Hardman and Holden Manesil Hardman and Holden Hoesch Chemische Fabrik Hoesch KG (Hetishyu) Sie-Stone Stoner Rubber Co. ) (Stoner rubber) Nalco Nalco Chem.Co. (Nalco) (Nalco chemical) In addition to the above-mentioned fillers, a filler having a weak oil adsorption property as a filler for the pressure roller, for example, quartz powder having a particle size of 1 to 5μ. ，
It is possible to use diatomaceous earth or the like.

Quso Philadelphia Quartz Co. (Fucking) (Fira del Fuia Quartz) Santocell Monsanto.Chemical Co. (Santocelle) (Mont Santo Chemical) Imsil Illinois Minerals Co. (Imsil) Calcium Silikat Chemische Fabrik HoeschK-G (Calcium Zillicat) Calsil Fiillstoff-Gesellschaft Marquart Fortafil Imperial Chemical Industries, Ltd. (Forutafil Imperial Chemical Industries, Ltd.) (Jesef Crossfield and Sons) Manosil Hardman and Holden (Manosir) (Hardman and Holden) Vulkasil Farbenfabriken Bryer, A.-G. Tufknit Durham Chemicals, Ltd. (Tafunitsuto) (Douruhamu Chemicals) Shirumosu Shiraishi Kogyo Sutaretsukusu Kamijima chemical Furikoshiru multi-wooden fertilizer and the like can be used.

The present invention is effective for heat fixing, but can also be applied to pressure fixing.

As the release agent used above, a viscous liquid such as silicone oil is preferable, but the same release agent can be used,
Not only silicone but also fluorine-based oil is possible. The expression “roller” also includes a belt-shaped rotating body.

A rubber material is particularly suitable for the elastic layer of the roller, but various mixed rubber layers, a mixed layer of rubber and resin, or an elastic layer made of an oil-containing resin may be used.

[Effect]

As described above, in the present invention, as the filler of the fixing roller elastic layer, one having a relatively strong releasing agent adsorption force is used, and as the filler of the pressure roller elastic layer, one having a relatively weak releasing agent adsorption force is used. As a result, it is possible to obtain a fixing device excellent in releasability over a long period of time by suppressing transfer of the release agent contained in the fixing roller to the pressure roller as much as possible.

[Brief description of drawings]

 The figure is an explanatory view of the main configuration of an embodiment of the present invention. 1 is a fixing roller, 2 is a pressure roller, and 11 and 21 are elastic layers.

Claims (4)

[Claims] 1. A fixing device comprising: a fixing roller that contacts a recording material carrying a toner image to fix the toner image on the recording material; and a pressure roller that is in pressure contact with the fixing roller. In a fixing device in which the surface layers of the fixing roller and the pressure roller are both formed of an elastic layer containing a filler, the elastic layer of the fixing roller contains the elastic layer of the pressure roller. The fixing device is characterized by containing a filler having a larger releasing agent adsorption force than the existing filler. 2. The fixing device according to claim 1, wherein the filler of the fixing roller is fine silica powder produced by a dry method. 3. The fixing device according to claim 2, wherein the filler of the pressure roller is fine silica powder prepared by a wet method. 4. The fixing device according to claim 1, wherein the amount of the filler of the fixing roller is smaller than the amount of the filler of the pressure roller.