JPH0922212A - Fixing roll - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing roll which does not exhibit triboelectrostatic chargeability by an increase in electric resistance over a long period and has excellent toner releasability and paper peelability. SOLUTION: This fixing roll 1 is composed of a rubber material of a three- layered structure successively laminated with an elastic layer 3, a conductive layer 4 and a release layer 5 from the inside toward the outside of the roll and is usable for both of a heat fixing roll and a pressure fixing roll. The volumetric resistivity of the conductive layer 4 is <=10<11> Ωcm. The release layer 5 consists of a fluororubber contg. substantially no fillers as compounding agent. The thickness of the conductive layer 4 is adequately in a range of 10 to 100μm and the thickness of the release layer 5 in a range of 5 to 30μm, respectively. Modified silicone oil is preferably applied as a release assistant on the surface of the release layer 5.

Description

Detailed Description of the Invention

[0001]

The present invention relates to an electrophotographic copying machine,
The present invention relates to a fixing roll in an image forming apparatus that uses an electrophotographic process such as a printer and a facsimile. More specifically, the present invention relates to a heat fixing roll or a pressure fixing roll made of a rubber material having a three-layer structure of an elastic layer, a conductive layer and a release layer.

[0002]

2. Description of the Related Art Conventionally, a fixing roll whose surface is formed of a rubber elastic body such as silicone rubber has a uniform contact with an object to be fixed such as a paper sheet, so that the fixing property and the image quality are improved.
It is known that there is an advantage that a good peeling action can be obtained for low-viscosity toner such as full-color toner.
In addition, when fixing an unfixed image such as a full-color image, if it is necessary to apply a release agent such as silicone oil to the surface of the fixing roll, coating the silicone rubber layer with a fluororubber layer greatly improves the durability of the fixing roll. The present inventors have already confirmed the improvement (for example, Japanese Patent Laid-Open No. 2-15).
No. 6282). It is also known that excellent toner releasability can be obtained by using a modified silicone oil described in JP-B-64-6464 and JP-A-4-348377 as the silicone oil.

[0003]

However, even if the above releasing agent is applied to the surface of the fixing roll, there is a problem in maintaining toner releasability and paper releasability for a long period of time in actual use. There are cases. The inventors of the present invention investigated the cause, and the fluorine rubber layer constituting the surface layer was heated under a fixing temperature condition for a long period of one year or more, so that the electric resistance thereof was increased and was remarkably high at the time of fixing. It has been clarified that triboelectric chargeability is exhibited, and as a result, paper jams and offsets occur mainly due to the electrostatic force effect. As a countermeasure against these problems, a method of adding a compounding agent such as an antistatic agent to the fluororubber for the purpose of preventing static electricity is conceivable. However, according to our investigation on this point, the prior art does not exist yet. Further, Japanese Patent Laid-Open No. 4-294375 discloses a fixing roll in which carbon black is added to a fluororubber of a surface layer as a reinforcing filler in order to improve wear resistance, and as a result, an antistatic effect is obtained. It is also possible to bring about. However, with this method, the toner releasability is remarkably impaired, and it is not possible to satisfy the requirements for high releasability such as color fixing.

As described above, the conventional fixing roll has a problem that it is difficult to maintain toner releasability and paper releasability for a long period of time. Therefore, the present invention is intended to solve the above problems,
It is to provide a fixing roll capable of exhibiting toner releasing performance and paper peeling performance for a long period of time. More specifically, a fixing roll for a full-color image forming apparatus that does not exhibit frictional electrification due to an increase in electric resistance even in a heating phase for a long period of time and has excellent maintainability of initial toner release performance and paper release performance is provided. To provide.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies on a means for preventing the charging potential of the fixing roll from rising due to heating for a long time while maintaining the toner releasing performance. By providing a conductive rubber layer as the undercoat layer of the surface layer, the charging potential of the fixing roll does not increase so much even after heating for a long period of time, and for example, according to the method for measuring the roll charging potential of Examples described later. It has been found that the potential can be maintained at 500 V or less and that no jam occurs. Further, as the surface layer, a fluororubber layer containing substantially no filler as a compounding component, except for the minimum necessary compounding agent for maintaining a sufficient crosslink density, has excellent maintainability of the toner releasing performance. I found out that The fixing roll having such a layered structure has completed the present invention based on the finding that not only excellent toner releasing performance but also excellent paper peeling performance is maintained for a long period of time. . That is, the fixing roll of the present invention is composed of a rubber material having a three-layer structure in which an elastic layer, a conductive layer and a release layer are sequentially laminated from the inside to the outside of the roll, and the conductive layer has a volume specific resistance of 10 ^{It is 11} Ωcm or less, and the release layer is made of a fluororubber containing substantially no filler as a compounding agent.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
As shown in FIG. 1, the fixing roll 1 of the present invention is made of a rubber material having a three-layer structure in which an elastic layer 3, a conductive layer 4 and a release layer 5 are sequentially laminated from the outer peripheral surface of a cored bar 2. Both ends 2a, 2a of the core metal 2 function as a rotation axis of the roll, and are solid cylinders made of metal such as steel, stainless steel, aluminum, aluminum alloy, alloy, or ceramic. A body or a hollow cylinder is used.

As the elastic layer 3, a rubber material having excellent heat resistance such as silicone rubber or fluororubber is used. When the fixing roll 1 is used as a heat fixing roll, for example, aluminum, iron, nickel, copper, zinc, tin, lead, magnesium oxide, alumina, zinc oxide, silica, boron nitride, silicon carbide and the like have good thermal conductivity. Silicone rubber or the like in which fine powder of inorganic material is dispersed is used. In particular, when the fixing roll 1 of the present invention is applied to a color image forming apparatus, the silicone rubber composition disclosed in JP-A-3-221982 is preferably used. That is, 100 to 500 parts of magnesium oxide fine powder that was fired at 1000 ° C. or higher with respect to 100 parts by weight of polyorganosiloxane.
A silicone rubber obtained by heating and curing the composition contained in the range of parts by weight is suitable. Magnesium oxide may be fine powder whose surface is treated with a silane coupling agent, a titanate coupling agent, polyorganosiloxane, or the like. The thickness of the elastic layer 3 is 0.5 to 4 in order to secure the nip width and the thermal conductivity at the time of fixing due to the elastic modulus of the rubber material.
mm is preferable.

The conductive layer 4 has a volume resistivity of 10 ¹¹ Ωcm.
The following rubber materials having excellent heat resistance such as silicone rubber and fluororubber are used. A conductivity-imparting agent is an essential component of the rubber material of the conductive layer 4, and known compounding agents such as a cross-linking agent, a cross-linking accelerator, a filler, and an anti-aging agent can be added if necessary. As the conductivity imparting agent, carbon black, graphite, metals such as aluminum, copper and tin, SnO _2-
Fine powder such as In ₂ O ₃ solid solution is used. Among them, carbon black is preferably used in terms of adhesion to the release layer 5 of the surface layer and heat resistance stability. The compounding amount of the conductivity-imparting agent varies depending on its physical properties, but is preferably in the range of 10 to 100 parts by weight with respect to 100 parts by weight of the rubber material. When the compounding ratio of the conductivity imparting agent is less than 10 parts by weight, the conductive layer 4
It is difficult to reduce the volume resistivity of 10 to 10 ¹¹ Ωcm or less. On the other hand, if it exceeds 100 parts by weight, the resistivity can be sufficiently reduced, but not only the hardness of the fixing roll 1 is increased more than necessary, but also the elasticity of the conductive layer 4 is lowered, and the conductivity is further reduced. The layer 4 itself becomes brittle. As the cross-linking agent, known compounds such as amines, bisphenols and peroxides are used. In order to accelerate the crosslinking reaction of the rubber material, various accelerating aids, magnesium oxide, MgO
It is preferable to add an acid acceptor such as -Al ₂ O ₃ solid solution together with the crosslinking agent. The compounding amount of these is preferably 10 parts by weight or less with respect to 100 parts by weight of the rubber material. The thickness of the conductive layer 4 is preferably in the range of 10 to 100 μm. If the thickness of the conductive layer 4 is less than 10 μm, the antistatic effect on the surface of the fixing roll 1 cannot be sufficiently exhibited. On the other hand, when the thickness is more than 100 μm, the thermal conductivity is lowered when the fixing roll 1 is used as a heat fixing roll.

The release layer 5 is made of fluororubber. As the fluororubber, a copolymer of VdF and hexafluoropropylene (HFP) containing vinylidene fluoride (VdF) as a main component, and a ternary copolymer of VdF-HFP copolymer and tetrafluoroethylene (TFE). Fluorine-based elastomers such as a combination (for example, "Viton" manufactured by Showa Denko Dupont, "Daiel" manufactured by Daikin Industries, Ltd.), an alternating copolymer of TFE and propylene (for example, "Aflas" manufactured by Asahi Glass Co., Ltd.), and the like. . In addition, VdF-chlorotrifluoroethylene copolymer, silicone rubber,
A mixture of fluorosilicone rubber or the like and the above-mentioned fluorine-based elastomer containing VdF as a main component can be used. These fluororubbers can also be used as a constituent material of the elastic layer 3 and the conductive layer 4. Various compounding agents can be added to the fluororubber of the release layer 5 as in the case of the conductive layer 4, but in the present invention, the minimum necessary compounding agent (crosslinking agent, for crosslinking the fluoropolymer, Other than the above-mentioned accelerating aid and cross-linking accelerator such as acid acceptor), substantially no filler is contained. If the release layer 5 contains a filler, not only the abrasion resistance and silicone oil resistance inherent to the fluororubber are impaired, but also the toner releasability is remarkably impaired. The thickness of the release layer 5 is preferably in the range of 5 to 30 μm. When the thickness of the release layer 5 is less than 5 μm, when the fixing roll 1 is used for a long period of time, the fluororubber gradually wears and the function as the fixing roll is impaired. On the other hand, when the thickness is more than 30 μm, if the fixing roll 1 is used as a heat fixing roll, the heat quantity from the internal heat source cannot be sufficiently transferred to the surface of the release layer 5.

The fixing roll 1 of the present invention is manufactured, for example, as follows. i) First, both ends 2a, 2a of the centrifugal metal mold coated with a release agent are positioned so that the core metal 2 is located at the center.
And the rubber material is injected into the mold to form a molded body of the elastic layer 3. Next, two tanks storing rubber material solutions having different compositions were prepared, and the rubber moldings were applied by dipping in each rubber material solution while rotating, and then the rubber layers were dried and vulcanized to form conductive layers. 4 and the release layer 5 are formed. In order to improve the adhesiveness of the boundary surface, the outer peripheral surface of the cored bar 2 and the surface of the conductive layer 4 are preferably treated with a primer. ii) The surface of the rubber molded body on which the elastic layer 3 is molded is coated with the rubber sheet of the conductive layer 4 and the release layer 5 separately or a laminated film in which both layers are adhered. iii) The tube-shaped laminated film is adhered to the inner surface of the mold in advance, and the rubber material is injected into the space between the core metal 2 and the laminated film in the same manner as in i) to mold the elastic layer 3. In this way, the fixing roll 1 can be manufactured.

The fixing roll 1 of the present invention can be used for either one or both of the heat fixing roll 6 and the pressure fixing roll 7, as shown in FIG. FIG. 2A shows an example in which the fixing roll 1 is used as the heat fixing roll 6, and the pressure fixing roll 7 has a structure in which the outer peripheral surface of the cored bar 8 is covered with the release layer 9. FIG. 2B shows an example in which the fixing roll 1 is used as the pressure fixing roll 7, and the heating fixing roll 6 has a structure in which the outer peripheral surface of the cored bar 8'is covered with the release layer 9 '. FIG. 2C shows an example in which the fixing roll 1 is used as a pair of heating fixing roll 6 and pressure fixing roll 7. A heat source (heater) 10 is built in the cored bars 2 and 8 ′ of each heating and fixing roll 6 that comes into contact with the unfixed toner image X on the recording medium (paper P).
A heater may be built in the pressure fixing roll 7 that comes into contact with the surface of the paper P opposite to the toner image X. In FIG. 2, when the paper P is passed through the nip portion between the heat fixing roll 6 and the pressure fixing roll 7, the fixing resin or wax of the unfixed toner image X is melted by heat conduction from the heater 10. After being passed through the nip portion, the toner image X is softened, and is fixed on the sheet P as a permanently fixed image Z. Note that FIG.
However, the fixing roll 1 can be applied to pressure fixing using, for example, microcapsule toner. In that case, it is not always necessary to install a heater inside the roll 1, and the nip pressure between the roll 1 and the other pressure fixing roll is set higher than in the case of the heat-type fixing.

Next, as an example, a heating type fixing device having the fixing roll 1 (6) and the pressure fixing roll 7 shown in FIG. 2A as constituent members will be described with reference to FIG. In FIG. 3, for the purpose of preventing the occurrence of offset on the surface of the fixing roll 6, a release auxiliary agent applying mechanism 11 is arranged on the side of the roll 6. The coating mechanism 11 includes a container 12 for storing a release auxiliary agent, a metering roller 13 whose outer peripheral surface is partially immersed in the release auxiliary agent, a metering blade 14 near the outer peripheral surface of the roller 13, and a fixing member. The roll 6 and the roller 13 are provided in contact with the donor roller 15. Further, the peeling claw 16 is arranged on the downstream side of the nip portion so that the leading edge portion contacts the surface of the fixing roll 6. On the other hand, on both sides of the pressure fixing roll 7, the paper carrying table 1
7 and the sheet unloading table 18 are arranged close to the outer peripheral surface of the roll 7. In this fixing device, the fixing roll 6 and the metering roller 13 are drive rolls rotated by a drive source such as a motor (not shown), and the pressure fixing roll 7 and the donor roller 15 are driven rolls.

In the fixing process, as described above, after the paper P passes between the fixing roll 6 and the pressure fixing roll 7, the unfixed toner image X on the paper P is fixed to the permanently fixed image Z. . At this time, the leading edge of the sheet P contacts the peeling claw 16 so that the sheet P is separated from the fixing roll 6 and the sheet unloading table 1
After passing through 8, the sheet is discharged to the outside of the fixing device. The amount of the release aid adhering to the surface of the metering roller 13 is adjusted by the metering blade 14, then moves to the donor roller 15 and adheres to the surface of the fixing roll 6. The release auxiliary agent prevents the unfixed toner image X from being offset on the surface of the fixing roll 6. Silicone oils, fluororesins, waxes and the like are used as the release aid. Above all, modified silicone oil is preferably used. As the modified silicone oil, a mercapto group disclosed in Japanese Patent Publication No. 64-6464,
Examples thereof include silicone oils having a functional group such as a carboxy group, a hydroxy group, an isocyanate group, an epoxy group, and an amino group, and the fixing release agent disclosed in JP-A-4-348377.

[0014]

The fixing roll of the present invention comprises an elastic rubber layer having a three-layer structure in which a surface coating layer is functionally separated into a release layer and a conductive layer, and a fluororubber which emphasizes toner releasing performance is selected as the surface layer. Is. Therefore, even if the electric resistance of the fluororubber increases when the fixing roll is used for a long period of time, the surface charge can be efficiently removed through the conductive undercoat layer. As a result, while maintaining the elasticity of the fixing roll, it is possible to simultaneously achieve high toner releasing performance and paper releasing performance, which could not be achieved in the past, and their maintenance.

[0015]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited to the following Examples. (Rubber material compounding examples and physical properties) According to the parts by weight shown in Table 1, V
Fluorine-based polymer known as dF-based terpolymer (trade name Viton B-50: Showa Denko DuPont)
And various compounding agents are mixed uniformly with an open roll,
Fluororubber compounds of Formulation Examples 1 to 6 were prepared.
These compounds are then 1
After vulcanizing at 80 ° C. for 40 minutes to form a rubber sheet having a thickness of 2 mm, secondary vulcanization treatment was performed at 230 ° C. for 4 hours to produce a fluororubber. In Table 1, to the fluororubbers of Formulation Examples 1 to 4, a crosslinking agent (vulcanizing agent, vulcanization aid), a crosslinking accelerator (acid acceptor), and a conductivity-imparting agent, which is a kind of filler, are added. ing. On the other hand, for the fluororubbers of formulation examples 5 and 6,
Compounding agents other than the above-mentioned crosslinking agent and crosslinking accelerator are not added.

[0016]

[Table 1] * 1 Hexafluoroisopropylidene bisphenol (Curative 30) * 2 Benzyltriphenylphosphonium chloride (Curative 20) * 3 Magnesium oxide (# 30: Kyowa Chemical Co., Ltd.) * 4 MgO / Al ₂ O ₃ solid solution (hydrotalcite) ) * 5 Carbon black (MTCarbon: made by Cabot) * 6 Carbon black (Printex L: made by Degussa)

A DC voltage of 10 was applied to the rubber sheets of formulation examples 1 to 6.
0V was applied, and the volume resistivity was measured with a super insulation resistance meter by the current / voltage method. Further, these rubber sheets were heated and aged for 10 days in an oven at 200 ° C., and then the change in the volume resistivity was measured by the same method. Also,
The hardness of the rubber sheet was measured according to "JIS A".
Table 2 shows the results.

[Table 2] As shown in Table 2, the initial volume resistivity is 10 ¹¹ Ωc.
In Formulation Examples 1 and 2 with m or less, the change in volume specific resistance after heat aging is small, and the antistatic performance is maintained as a physical property of the material. On the other hand, in formulation examples 3 to 6 in which the initial volume resistivity is larger than 10 ¹¹ Ωcm, the volume resistivity after heat aging is increased by 1.2 to 1.7 digits, and the electrical insulation property is increased. I understand.

(Fixing roll) On the other hand, using a roll die and a press vulcanizer, silica-containing silicone rubber is vulcanized and adhered onto a hollow aluminum cored bar via a primer, and then cylindrical grinding is performed. An outer layer was polished by a disk to form an elastic layer. While rotating the obtained roll-shaped silicone rubber, a compound for fluororubber having a different composition is provided on the outer peripheral surface thereof via a primer (compounding examples 1 to 1).
After dip coating in the following solution of 6), it was heated and cured to form a conductive layer. Similarly, a release layer was formed on the conductive layer. Fluoro rubber solution Compound for fluoro rubber 15 parts by weight Methyl ethyl ketone 60 parts by weight Methyl isobutyl ketone 25 parts by weight Of the rolls manufactured as described above, the core metal is 75 parts by weight.
A roll having a built-in 0 W lamp heater was used as a heat fixing roll shown in Table 3, and a roll not having a built-in heating source was used as a pressure fixing roll shown in Table 4 and subjected to a fixing test described later.
The pressure fixing roll has the same structure as the heat fixing roll shown below except that the outer diameter of the core metal is 48 mm and the thickness of the elastic layer is 1 mm. Heat fixing roll Roll outer diameter 50 mm Core metal outer diameter 44 mm Elastic layer thickness 3 mm Thermal conductivity 0.65 W / m · deg Hardness (JIS A) 60 ° Conductive layer thickness 20 μm Release layer thickness 20 μm

[0019]

[Table 3]

[Table 4]

(Image Forming Apparatus) FIG. 4 is an overall view of a color image forming apparatus (digital color copying machine; "Acolor" manufactured by Fuji Xerox Co., Ltd.) in which a roll member of a fixing device is modified. In FIG. 4, the light reflected by the document illuminating lamp 22 moving along the lower surface of the document (not shown) placed on the platen 21 is reflected by the moving mirror unit 23, the lens 24, and the fixed mirror. The image is converged on the image reading unit 26 via 25. The image reading unit 26 is composed of a color CCD sensor having a large number of photoelectric conversion elements and filters of three colors of red, green and blue. The image reading unit 26 converts the original image into an electric signal for each color, and further inputs the electric signal to the optical writing signal output device 27. The optical writing signal output device 27 outputs the original image reading signals input for each of the three colors as yellow (Y), magenta (M),
It is converted into digital signals of four colors of cyan (C) and black (K), stored, read out at a predetermined timing, and output to a light beam writing device 28 as a means for writing an electrostatic latent image. The light beam writing device 28 writes electrostatic latent images corresponding to the above four colors on the surface of the image carrier 29.

Around the image carrier 29, a charging charger 30 for uniformly charging the surface of the image carrier 29, and an electrostatic latent image written on the image carrier 29 are developed into toner images of respective colors. A developing device 31, a sheet carrying member 32 composed of a cylindrical rotatable transfer drum, a charge eliminating corotron 33, and a cleaner unit 34 are arranged. The developing device 3
Reference numeral 1 denotes a developing device for each color of Y, M, C and K, and develops the electrostatic latent image with toner of each color. Inside the above-mentioned paper carrying member 32 whose surface forms a paper attracting surface, a transfer charging device 35 for attracting paper and transferring a toner image is in a transfer position where the surface of the paper carrying member 32 and the surface of the image carrier 29 come into contact with each other. It is located in Q. Further, the cleaner unit 34 supports a cleaning blade 34a, the charging charger 30, and a static eliminator 36 including a red LED. A paper sensor 37, a post-transfer jam sensor 38, a charge eliminating corotron 39, and a cleaner 40 are arranged around the paper carrying member 32. The paper sensor 37 is arranged on the upstream side of the transfer position Q and close to the surface of the paper carrying member 32, and detects the leading end position of the paper P adsorbed on the paper adsorbing surface. The post-transfer jam sensor 38 is arranged on the downstream side of the transfer position Q and detects the presence / absence of the paper P based on the amount of light reflected from the surface of the paper carrying member 32. The paper P stored in the paper feed tray 41 is taken out by the paper take-out roll 42 and conveyed, and is temporarily stopped by the pair of registration rolls 43. The paper P is transferred from the registration roll 43 to the transfer position Q at the same timing as the toner image on the surface of the image carrier 29 moves to the transfer position Q thereafter.
Is supplied to.

Transfer position Q by the paper feed mechanism (41 to 43)
The leading end of the paper P supplied to the paper is adsorbed on the paper suction surface on the surface of the paper carrying member 32. At the same time when this paper is adsorbed,
The color toner image is transferred from the surface of the image carrier 29 to the paper P. Here, the optical writing signal output device 27 first reads the Y digital signal at a predetermined timing and outputs it to the optical beam writing device 28. The writing device 28 writes an electrostatic latent image corresponding to Y color on the surface of the image carrier 29. Y
The electrostatic latent image corresponding to the color is developed into a Y-color toner image by the developing device 31, and the paper P is supplied from the paper feeding mechanism to the transfer position Q at the same timing as the movement of the Y toner image to the transfer position Q. To be done. The paper carrying member 3 is opposed to the transfer position Q.
2 the transfer charger 35 arranged inside
The paper P supplied to the paper is sucked onto the paper suction surface,
The Y toner image on the surface of the image carrier 29 (1
(Color toner image) is transferred.

The writing of the Y-color electrostatic latent image by the exposure system (22 to 25) is completed by the time the leading edge of the paper P onto which the first-color Y toner image is transferred reaches the position of the paper sensor 37. . When the leading edge of the sheet P is detected by the sheet sensor 37, writing of the electrostatic latent image of the second color M by the exposure system is started. Then, when the front end of the paper P on which the Y toner image is transferred reaches the transfer position Q, the transfer charger 35
Thus, the transfer of the second color M toner image is performed. Then, the transfer of the C toner image and the K toner image is performed in the same manner as the transfer of the M toner image. The paper P on which the toner images of the respective colors (Y, M, C, K) are transferred onto the paper carrying member 32 is peeled by the peeling claw 44, and the pair of the heat fixing roll 6 and the pressure fixing roll 7 are mounted. Then, it is conveyed to the fixing device 45. After the transfer toner images of the four colors are fixed by the fixing device 45, the paper P that has received the conveyance force of the pair of paper discharge rolls 46 is discharged to the paper discharge tray 47.

(Fixing Test) Next, as a roll member of the fixing device 45, a pair of the rolls 1 to 6 and the roll 1 respectively.
6 and a pair of rolls 6 and the color image forming apparatus U equipped with rolls 11 to 16 were operated, and a fixing test was performed. In this fixing test, the toner offset properties of the heat fixing rolls 1 to 6 were evaluated, and double-sided copying was performed to evaluate the image defects (gloss unevenness) of the pressure fixing rolls 11 to 16. Further, the running property of thin paper (paper peeling property) was evaluated for each roll, and the roll charge potential after heat aging was measured by a surface potential meter (Model 344: manufactured by Trek). The evaluation results of the heat fixing rolls 1 to 6 and the pressure fixing rolls 11 to 16 are shown in Tables 5 and 6, respectively. As for the offset property, the fixing process of a full-color image was continuously performed using A4 paper, and the durability up to the occurrence of offset was evaluated. The paper peelability of the heat fixing roll was evaluated by wrapping the paper around the roll when a high-density image was formed on the leading end of the paper without providing a peeling auxiliary means such as a peeling claw (see reference numeral 16 in FIG. 3). The paper peeling property of the pressure fixing roll was evaluated by using a paper on which the toner image was not transferred (that is, a blank paper) and whether or not the paper was wrapped around the roll after the paper was subjected to a moisture absorption treatment.

[0025]

[Table 5]

[0026]

[Table 6]

As is clear from Tables 5 and 6, the fixing roll of the present invention has an excellent releasing performance for toner, and does not attract the paper due to triboelectrification even after a long-term heating and aging, thus eliminating static electricity. It can be seen that stable peeling performance is maintained without requiring an additional antistatic mechanism such as a device. It was also confirmed that even after the offset durability was evaluated, excellent performance was maintained without causing other problems such as abrasion. Further, the fixing roll of the present invention exhibits more excellent effects in full-color fixing, as is clear from the fixing test.

Although the embodiment of the present invention has been described in detail above, the present invention is not limited to the above embodiment, and various modifications can be made within the scope of the claims.
In the examples, an example in which the fixing roll of the present invention is attached to a color image forming apparatus has been shown as an example, but the fixing roll of the present invention is a variety of image forming apparatuses utilizing an electrophotographic process,
For example, it can be applied to a mono-color image forming apparatus. Also in the fixing of the monochromatic toner, the fixing property and the high image quality of the rubber fixing roll can be better achieved.

[0029]

According to the present invention, since the fixing roll has a layer structure in which a release layer made of fluororubber and a conductive layer having an antistatic function are functionally separated, both the heating fixing roll and the pressure fixing roll are provided. Even when used for, while retaining the original excellent wear resistance and silicone oil resistance of fluororubber,
It is possible to realize a fixing roll having excellent maintainability of toner release performance and paper release performance. According to the present invention, as described above, since the charging potential of the fixing roll does not rise for a long period of time, it is possible to significantly reduce the occurrence of paper jam.

[Brief description of drawings]

FIG. 1 is an explanatory view of a fixing roll shown as an embodiment of the present invention, FIG. 1A is a vertical sectional view thereof, and FIG. 1B is a sectional view taken along line IB-IB of FIG. 1A.

2A to 2C are explanatory views showing an example of use of the fixing roll of the present invention.

FIG. 3 is an explanatory diagram of a fixing device equipped with a fixing roll of the present invention.

FIG. 4 is an overall view of an image forming apparatus equipped with a fixing roll of the present invention.

[Explanation of symbols]

1 ... Fixing roll, 3 ... Elastic layer, 4 ... Conductive layer, 5 ... Release layer.

Claims (3)

[Claims] 1. A rubber material having a three-layer structure in which an elastic layer, a conductive layer and a release layer are sequentially laminated from the inside to the outside of a roll, and the conductive layer has a volume resistivity of 10 ¹¹
Ωcm or less, and the release layer is made of fluororubber substantially containing no filler as a compounding agent. 2. The conductive layer has a thickness of 10 to 100 μm, and the release layer has a thickness of 5 to 30 μm.
The fixing roll described. 3. The fixing roll according to claim 1, wherein a modified silicone oil as a release aid is applied to the surface of the release layer.