JP3496909B2 - Pressure roller and fixing device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat fixing type fixing device and a pressure roller used in the fixing device.

[0002]

2. Description of the Related Art In a conventional fixing device of a so-called heat fixing system, fixing is performed by applying heat to an unfixed developer (hereinafter referred to as toner) on a transfer material while applying pressure. However, at this time, it is necessary to stably convey the transfer material to the paper discharge section while preventing the offset phenomenon of the semi-melted toner or the melted toner, and therefore the pressure roller is used under severe conditions of high temperature and high pressure. Transportability at
High performance is required in terms of releasability, wear resistance, fixability and durability.

As such a pressure roller, for example,
A core roller made of aluminum, iron, stainless steel or the like is coated with an elastic layer having a releasability and heat resistance such as silicone rubber. The pressure roller is a heat roller type fixing device using a spring or the like. The fixing roller and the fixing film and the heater in the on-demand type fixing device are pressure-contacted and are rotatably driven.

Therefore, when the transfer material carrying the unfixed toner image is conveyed to the fixing roller or the fixing film and the pressure contact portion between the heater and the pressure roller, the transfer material has a predetermined heat energy at the pressure contact portion. The toner image is conveyed while being clamped, and the toner image is fixed on the transfer material.

[0005]

However, in the above-mentioned conventional apparatus, the pressure roller is frictionally charged during sheet passing,
For example, the transfer material is charged to 3 kV or more, so that the transfer material is wound around the pressure roller, or the unfixed toner is scattered by the electric field of the pressure roller, and an image defect such as electrostatic offset or line tailing occurs, the pressure roller surface. There was a case where the toner stain of No. 1 occurred.

Therefore, as a method for preventing the rubber surface of the pressure roller from being contaminated, for example, a method in which fluorine-based polysiloxane is mixed into the rubber (Japanese Patent Laid-Open No. 62-236842, etc.), or the rubber surface is released from the mold. A method has been proposed in which various low surface energy substances are mixed into rubber to improve surface properties, thereby lowering the surface energy.

However, even if the above method is applied to the pressure roller, the effect is not sufficient as in the case of applying it to a general rubber product due to the increase in the offset amount due to the frictional electrification of the pressure roller. there were.

Also, as a measure against frictional electrification of the pressure roller, a method has been proposed in which a static elimination brush is brought into contact with the pressure roller and grounded. However, this method also has a potential reduction of only 1 to 2 kV, and thus has a static elimination effect. Sometimes it wasn't enough.

Furthermore, in the technique of using a conductive rubber in the pressure roller, carbon, for imparting electrical conductivity by mixing a large amount of metal powder or the like, is that the surface energy of the rubber material is high Oh Ri, Therefore, releasability of the roller there is to Rukoto liable to occur the toner fouling decreases.

Therefore, it is an object of the present invention to provide a pressure roller that reliably prevents electrification due to friction and does not deteriorate the releasability, and a fixing device equipped with this pressure roller. .

[0011]

According to the first invention of the present application, the above object is achieved by directly or on a fixing roller which is formed by having a silicone rubber layer on a core metal and which contains a heating source. In a pressure roller which is arranged so as to be in pressure contact with a heating source through a fixing film and which conveys a transfer material carrying an unfixed developer image at the pressure contact portion under pressure, organic phosphorus is contained in the silicone rubber layer. This is achieved by including a salt.

Further, according to the second invention of the present application, the above object is achieved by adding 0.1 to 5% by weight of the organic phosphorus salt to the silicone rubber in the first invention. .

According to the third invention of the present application,
The above-mentioned object is to form a fixing roller containing a heating source or a fixing film in sliding contact with the heating source, and a silicone rubber layer on a core metal, and to heat the fixing roller directly or through the fixing film. In a fixing device, which comprises a pressure roller arranged so as to come into pressure contact with a source, and conveys a transfer material carrying an unfixed developer image at the pressure contact portion with a pressure, an organic phosphorus is contained in the silicone rubber layer. This is achieved by including a salt.

According to the fourth invention of the present application,
The above object is achieved by adding the organic phosphorus salt in an amount of 0.1 to 5% by weight to the silicone rubber in the third invention.

That is, in the first invention according to the present application, the resistance of the silicone rubber is uniformly reduced without increasing the surface energy by including the organic phosphorus salt in the silicone rubber layer of the pressure roller. The frictional charge with the transfer material is reduced, and since the organic phosphorus salt is present in the rubber in an ionic state, there is no resistance unevenness and the surface potential unevenness is suppressed to a low level to prevent the occurrence of electrostatic offset.

Further, in the second invention of the present application, since the organic phosphorus salt is added in an amount of 0.1 to 5% by weight with respect to the silicone rubber, the resistance of the pressure roller is sufficiently reduced and the transfer with the pressure roller is performed. Does not saturate the function of preventing frictional electrification with materials.

Further, in the third invention according to the present application, by including an organic phosphorus salt in the silicone rubber layer of the pressure roller in the fixing device, the resistance of the silicone rubber is made uniform without increasing the surface energy. Since it reduces the frictional electrification with the transfer material, and because the organic phosphorus salt is present in the rubber in the ionic state, there is no resistance unevenness, and the surface potential unevenness is kept low to prevent the occurrence of electrostatic offset. A good fixing operation is performed without stains and winding of the transfer material.

Furthermore, the fourth aspect of the present application In the invention of
Is 0.1 to 5 weight of organic phosphorus salt with respect to silicone rubber
%, The resistance of the pressure roller is sufficiently reduced and
Saturates the function of preventing frictional electrification between the pressure roller and transfer material.
Good quality without toner stains and transfer material wrapping.
Wear the clothes for a long time.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the accompanying drawings, and also an experimental example performed based on the present embodiment will be described.

In FIG. 1, reference numeral 1 a is a metal core metal member of the pressure roller 1, which is formed in a cylindrical shape. A silicone rubber layer 1b is arranged on the core metal member 1a, and an organic phosphorus salt is added to the silicone rubber layer 1b. By adding an organic phosphorus salt, which is an ionic conductive agent, to the silicone rubber, it is possible to uniformly reduce the resistance of the silicone rubber without increasing the surface energy, reduce frictional charging with the transfer material, and electrostatic offset, It was possible to prevent the transfer material from wrapping around the pressure roller, and to prevent the toner from adhering to the surface.

When the resistance of the pressure roller 1 of the present invention is measured,
Roll 1 x 10^Ten~ 1 x 10¹¹Ω and organic phosphorus salt
Approximately 1/10 compared to the case without addition ~ 1/100 lower
It was confirmed.

To measure this resistance, as shown in FIG. 2, the pressure roller 1 is brought into contact with the aluminum roller 5 in the external fixing idle rotation unit, and the pressure between the metal core 1a of the pressure roller 1 and the aluminum roller 5 is increased. The resistance was measured by using a 4329A high resistance meter manufactured by HP as a resistance measuring device 6. At this time, the pressure roller 1 had a silicone rubber wall thickness of 4 mm, and the nip between the pressure roller and the aluminum roller was 3 mm.

Further, as shown in FIG. 3, in a laser printer provided with the pressure roller 1 of this embodiment, a Model 344 surface electrometer manufactured by TREK Co., Ltd. is used as the surface potential measuring device 8, and the probe of the surface electrometer is used. When the surface potential of the pressure roller 1 of the present invention was measured by approaching 9 to the surface of the pressure roller during the passage of the transfer material, the pressure roller 1 of the present invention was about -80 to -250 V. It was confirmed that the surface potential was significantly reduced as compared with the case where no addition was made.

Further, as shown in FIG. 4, in the laser printer provided with the pressure roller 1 of this embodiment, the measuring needle 11 attached to the electrode plate 10 is brought into contact with the rubber layer of the pressure roller, and its induced potential is changed. When measured in the same manner as in FIG. 3, the pressure roller 1 of the present invention has a surface potential unevenness of about 0 to 20 V, which is significantly higher than that when the resistance is lowered by carbon or metal powder of 1000 V or more. It was confirmed that the unevenness of the image was reduced.

This is because when the resistance is lowered by carbon or metal powder, the overall triboelectrification is low, but a sea-island structure is formed in rubber, and high resistance areas and low resistance areas are mixed, resulting in large potential unevenness. but, in the case of adding an organic phosphorus salt as the pressure roller of the present invention, because there is no resistance unevenness due to the presence in the ion state in the rubber.

Therefore, when the resistance is reduced by carbon or metal powder, electrostatic offset occurs due to potential unevenness, but the pressure roller of the present invention does not generate electrostatic offset.

The organic phosphorus salt is added in an amount of 0.1 to 5% by weight based on the silicone rubber. This is 0.1
If the content is less than 5% by weight, the resistance of the pressure roller does not sufficiently decrease, and the effect of preventing triboelectrification between the pressing roller and the transfer material is not obtained. If it is 5% by weight or more, the effect of preventing triboelectrification is saturated. Is.

Next, an experimental example performed based on this embodiment and a comparative example performed for comparison will be described.

[Experimental Example 1] First, as Experimental Example 1, a viscosity of 900 poise composed of 100 parts of vinyl group-containing diorganopolysiloxane, 5 parts of dry fine powder silica, 20 parts of quartz powder, 1 part of red iron oxide and a platinum catalyst. From liquid A, which is an addition reaction type liquid silicone rubber composition, and 100 parts of a mixture of vinyl group-containing diorganopolysiloxane and active hydrogen-containing diorganopolysiloxane, 5 parts of dry fine powder silica, 20 parts of quartz powder, and 1 part of red iron oxide Liquid B which is an addition reaction type liquid silicone rubber composition having a viscosity of 600 poise
After mixing 100 to 100, 3% by weight of tetraethylphosphonium bromide (trade name: Hishicolin PX-2B manufactured by Nippon Kagaku Kogyo Co., Ltd.) was dissolved in water, and then mixed and stirred with the above mixture to remove the mixture. After foaming, a cored bar having a diameter of 10 mm and coated with a siloxane-based primer made of stainless steel was set in advance, and injection molding was performed in a cylindrical mold preheated to 130 ° C. and held at the above temperature for 10 minutes. And cured to obtain the pressure roller of the present invention.

The pressure roller thus obtained had an outer diameter of 17 mm, and the resistance measured by the method of FIG. 2 was 2 × 10 ¹⁰ Ω.

This pressure roller is used as a laser printer LBP.
It was installed in a fixing device of -A404PS-Lite (manufactured by Canon), and the image durability test and the surface potential of the pressure roller at the time of paper passing were measured by the method of FIGS. 3 and 4 under the following conditions. The fixing roller is 30 μm on an aluminum cored bar with an outer diameter of 25 mm
A thick PFA tube fusion-coated was used.

(Fixing conditions) Surface temperature of fixing roller: 150 ° C. Tightening pressure between fixing roller and pressure roller: 6 kgf Paper passing paper: A4 plain paper for test pattern printing Paper passing speed: 4 sheets / min. Did not clean the surface of the fixing roller.

As a result, the surface potential of the pressure roller at the time of passing the paper was -100V and the potential unevenness was 10V. The electrostatic offset image did not occur after passing 100,000 sheets. Further, the surface of the pressure roller was not soiled with toner, and the paper did not wind around the pressure roller.

Comparative Example 1 Next, as Comparative Example 1, a pressure roller was prepared in the same manner as in Experimental Example 1 except that tetraethylphosphonium bromide was not added, and the same evaluation as in Experimental Example 1 was performed. The pressure roller of Comparative Example 1 had a resistance of 3 × 10 ¹² Ω.

As a result, the surface potential of the pressure roller during paper passing was -3000 V, and an electrostatic offset image was generated from the beginning. Also, the toner stain on the surface of the pressure roller is 300
It occurred in 0 sheets and thereafter, the winding of the paper around the pressure roller was so severe that it could not be put to practical use. In particular, when the OHP paper coated on the surface was passed, it was wound around the pressure roller from the beginning.

Comparative Example 2 Further, as Comparative Example 2, 100 parts of silicone rubber compound SH841U (manufactured by Toray Silicone Co., Ltd.) and 3 parts of RC-4 (manufactured by Toray Silicone Co., Ltd.) as a cross-linking material were used. Chen Black E
What contained 5 parts of C (manufactured by Lion Corp.), kneaded and dispersed by two rollers, and pressed it into a cylindrical mold having a cored bar previously coated with a siloxane primer made of stainless steel and having a diameter of 10 mm. Primary vulcanization 165
C./minute, secondary vulcanization at 200.degree. C./hour for 2 hours to prepare a pressure roller containing carbon black, and the same evaluation as in Experimental Example 1 was performed. The pressure roller of Comparative Example 2 had an outer diameter of 17 mm as in Experimental Example 1, and the resistance by the method of FIG. 2 was 1 × 10 ¹¹ Ω.

As a result, the surface potential of the pressure roller at the time of passing the sheet by the method of FIG. 3 was −250 V, but when the surface potential was measured by the method of FIG. 4, the potential unevenness was 1200 V,
An electrostatic offset image was generated from the beginning. Also, since the surface energy is high, toner stains occur on 7,000 sheets,
After that, the wrapping of the paper around the pressure roller was so bad that it could not be put to practical use.

Experimental Example 2 Next, as Experimental Example 2, tetra-n-butylphosphonium chloride (trade name: Hishicolin PX-4C, manufactured by Nippon Kagaku Kogyo Co., Ltd.) was added to the organic phosphorus salt.
Was prepared in the same manner as in Experimental Example 1 except that 0.2% by weight of silicone rubber was added.
The same evaluation as was done.

As a result, the surface potential of the pressure roller at the time of passing the paper was -200V and the potential unevenness was 60V. The electrostatic offset image did not occur after passing 100,000 sheets. Further, although the toner stain on the surface of the pressure roller was slightly generated at the end of 80,000 sheets, there was no problem in practical use, and the paper was not wrapped around the pressure roller up to 100,000 sheets.

Table 1 shows the evaluation results of the above experimental examples and comparative examples.
Are shown together.

[0041]

[Table 1]

In the present embodiment, the case where the present invention is applied to the fixing device of the type using the fixing roller has been described, but it is disclosed in JP-A-63-313182 and JP-A-2-
No. 157878, JP-A-4-44075-4408.
As disclosed in Japanese Patent Publication No. 3 etc., a heat source is adhered to one surface side of the heat resistant film and a transfer material is adhered to the other surface side of the heat resistant film so that the transfer material travels along with the film to transfer the heat energy of the heat source through the film. The present invention can also be applied to a transfer material and a fixing device that applies a toner image on the transfer material.

The present invention can also be applied to a fixing device of a so-called magnetic induction heating system in which a heat-resistant film having a metal layer or a roller made of metal is heated by generating an eddy current by magnetic induction heating.

[0044]

As described above, the first aspect of the present application
According to the invention of claim 1, by containing an organic phosphorus salt in the silicone rubber layer of the pressure roller, the resistance of the silicone rubber is uniformly reduced without increasing the surface energy, so that the triboelectrification with the transfer material is reduced. Since the organic phosphorus salt exists in the rubber in an ionic state, there is no resistance unevenness, and the surface potential unevenness can be suppressed to a low level to prevent the occurrence of electrostatic offset.

Further, according to the second invention of the present application, since the organic phosphorus salt is added in an amount of 0.1 to 5% by weight with respect to the silicone rubber, the resistance of the pressure roller can be sufficiently reduced, and It is possible to prevent saturation of the effect of preventing frictional electrification between the pressure roller and the transfer material.

Further, according to the third invention of the present application, by including an organic phosphorus salt in the silicone rubber layer of the pressure roller in the fixing device, the resistance of the silicone rubber can be made uniform without increasing the surface energy. The frictional charge with the transfer material can be reduced, and since the organic phosphorus salt is present in the rubber in an ionic state, there is no resistance unevenness and the surface potential unevenness is suppressed to a low level to generate electrostatic offset. Therefore, it is possible to perform a good fixing operation without toner stains and transfer material winding.

Furthermore, according to the fourth invention of the present application, since the organic phosphorus salt is added in an amount of 0.1 to 5% by weight with respect to the silicone rubber, the resistance of the pressure roller can be sufficiently reduced, and Since the effect of preventing frictional electrification between the pressure roller and the transfer material can be prevented from being saturated, a good fixing operation can be performed for a long period of time without toner stains and transfer material winding.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a pressure roller and a fixing device in which the pressure roller is installed according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a method for measuring resistance of a pressure roller according to an embodiment of the present invention.

FIG. 3 is a schematic diagram showing a method of measuring the surface potential of a pressure roller according to an embodiment of the present invention.

FIG. 4 is a schematic diagram showing a method for measuring minute potential unevenness of the pressure roller surface potential according to the embodiment of the present invention.

[Explanation of symbols]

1 pressure roller 1a core metal 1b Silicone rubber layer 2 fixing roller 3 heater (heating source) 7 Transfer material

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G03G 13/20 G03G 15/20 F16C 13/00

Claims (4)

(57) [Claims] 1. A silicone rubber layer is formed on a core metal and is arranged so as to be in pressure contact with a heating source directly or via a fixing film, and to the fixing roller enclosing the heating source. A pressure roller for conveying a transfer material carrying an unfixed developer image under pressure, wherein the silicone rubber layer contains an organic phosphorus salt. 2. An organic phosphorus salt is added to silicone rubber in an amount of 0.
The pressure roller according to claim 1, wherein 1 to 5% by weight is added. 3. A fixing roller containing a heating source or a fixing film slidably in contact with the heating source, and a silicone rubber layer on a core metal. The fixing roller is formed directly on the fixing roller or via the fixing film. In a fixing device, which comprises a pressure roller arranged so as to come into pressure contact with a heating source, and which conveys a transfer material carrying an unfixed developer image at the pressure contact portion under pressure, an organic material is added to the silicone rubber layer. A fixing device comprising a phosphorus salt. 4. The organophosphorus salt is added to silicone rubber in an amount of 0.
The fixing device according to claim 3, wherein 1 to 5% by weight is added.