JPS5890671A - Fixing device - Google Patents

Abstract

PURPOSE:To hold the strength of two rotating bodies which clamp and carry a supporting materials for supporting an unfixed image and to improve the releasing properties, by forming their surface layers of a mixture of fluororubber and fluororesin. CONSTITUTION:A heat roll 1 rotates as shown by an arrow 161, and a press roll 2 rotates in friction contact with the external circumferential surface of the roll 1 as shown by an arrow. This roll 1 is formed by providing a mixed surface layer of fluororubber and fluororesin to the external circumferential surface of a metallic heat roll core 3 to a 100mu thickness, and incorporates a heater 5. The heat roll 1 is formed by coating the hollow roll core 3 with a solution prepared by mixing a 7pts.wt. hardener liquid with fluororubber, fluororesin, and a 100pts.wt. compounding agent dispersed in water to a 100mum thickness, and then baking it at 350 deg.C for 30min. The press roll 2 is obtained by providing a relatively thick silicone rubber layer 7 around the external circumferential surface of a metallic roll core 6, and consequently both rolls 1 and 2 have a wide press- contacting area 18.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic device, an electrostatic recording device, a powder g1v
The present invention relates to an improvement of a fixing device for an image forming apparatus, and more particularly, to an improvement of a fixing device having a rotating body such as a roller.

Offset has been prevented by providing a sticky material and, in some cases, further applying a mold release agent such as silicone oil.

The surface of the fixing roller coated with flTV silicone rubber does not need to be coated with a general Kll molding agent, the equipment is simple, and the elasticity of the silicone rubber provides good fixing properties, but the releasability is poor. Changes (deterioration) over time are severe, the lifespan is very short, and the rollers had to be replaced frequently. Also, if you apply a mold release agent such as silicone oil to maintain mold releasability, the silicone rubber will swell with the silicone oil and its physical strength will decrease. It has higher strength than silicone rubber, and has good mold releasability when coated with silicone oil.

However, due to lack of elasticity, compared to the above-mentioned silicone rubber roller, the fixing properties are poor, and when there is an object that crushes the #J when fixing the toner image on the toner image support material,
If hard dirt adheres to the cylinder and enters between the cylinder and the object, there is no place for the force to escape, and the roller is likely to be damaged.

The above difference in fixing performance is due to the fact that when using an elastic material such as silicone rubber, the shape of the fixing roller follows the unevenness of the supporting material and the unevenness of the toner image on the supporting material, resulting in uniform contact with the entire surface. It is considered that the fixing properties are good.

In the case of a rigid body such as myoteflon, due to the unevenness of the support material and toner image, the convex portions make strong contact with the four-layer, and the concave portions only make unstable contact with the roller, so fixing in the concave portions is extremely difficult. It is thought that it will be very sweet.

From experimental results, it has been found that the same toner image can be completely fixed using silicone rubber at a temperature 20 to 25° C. lower than that using Teflon.

Further, 4I Publication No. 48-85151 discloses a fixing roller made of a mixture of tetrafluoroethylene resin powder and raw silicone rubber, but in this case, silicone and Teflon have poor compatibility (poor dispersibility, Another problem is that the adhesion is poor, resulting in very low strength. Also, when a release agent such as silicone oil is applied, the silicone rubber swells with oil, resulting in a very large decrease in physical strength. There are many points.

The present invention improves the above-mentioned conventional drawbacks.

It is an object of the present invention to provide a long-term release and constant fixation device.

The present invention will be described below with reference to Examples.

FIG. 1 shows an embodiment of the present invention.

1 is rotated in the direction of arrow 161 by a heating roller, and outside of it -
The pressure roller 2 slides on the circumferential surface and rotates in the direction of the arrow.

This heating lower 1 is the outer periphery wK7 of the metal hollow p-ra holder 3.
It has a mixed surface layer 4 of tunic rubber and fluorocarbon resin with a thickness of 100j1, and has a heater 5 such as a halogen heater inside. The heating roller 1 is made by coating a hollow roller core s with a solution of 100 parts by weight of fluoro rubber and fluoro resin dispersed in water, mixed with 7 parts by weight of a hardening agent liquid, and then heating it at 350°C. It was baked and shaped for 30 minutes.

The pressure roller 2 is brought into pressure contact with at least the heating roller 1 during fixing by a known pressure means, and has a relatively thick silicone rubber layer 7 provided on the outer peripheral surface of the metal Il roller core 6. One purpose of this configuration is to secure a pressure contact area 18 with the heating roller.

A temperature sensing element 8 such as a thermometer or a thermocouple is disposed on the outer peripheral surface of the heating roller 1, and its detection signal is guided to a known control means 15tC, and the temperature of the outer surface of the heating roller 1 is controlled by a heater 5.
By controlling the static output or its applied voltage, the toner is kept at a high melting temperature.

Paper P having unfixed toner @T is inserted between both rollers 1 and 2 from the direction of arrow 16, and after the toner gaT is fixed by the nipping conveyance and the one-time imprint heating, the paper P is discharged from the apparatus. . In order to reliably separate the paper P from the heating roller at this time, a plurality of separating claws 9 are provided in contact with the surface layer 4 along the roller axis direction.

10 is an applicator for applying an anti-offset liquid to the heating roller 1;
1, an anti-offset liquid such as silicone oil is applied to the surface of the heating roller in minute amounts. Reference numeral 16 denotes a spill prevention member for preventing the offset prevention liquid from spilling due to one vibration during transport of the machine, and is made of urethane foam. Reference numeral 14 denotes a tube that ensures uniform contact of the porous membrane 11 with the heating roller, and is a shape-retaining member that maintains the shape of j*11 and the state of pressure contact with the heating roller 1. This tube 14 has fine continuous pores made of the same material as the continuous pore membrane 11 .

For the membrane 11 and tube 14, a porous tetrafluoroethylene thin film (manufactured by Sumitomo Electric Industries, Ltd., trade name: Fluorobor) is used. (Porosity: 80%, pore size: 0.5-1.5μ) As an anti-offset liquid, dimethyl silicone oil with viscosity [
10,000 cs (KF-951 () manufactured by Shin-Etsu Chemical Co., Ltd. is used.The angle β (〉0) is defined by the straight line connecting the centers of the roller pair with respect to the transport direction L2 yc of the paper P. The angle α (>0) between the guide member 17, which is located in front of the roller pair and guides the paper P toward the heating roller, and the conveyance direction L2 is assumed to be 906>β>α in this embodiment. 〉
It is 0.

In the fixing device with the above configuration, the diameter of the heating roller was set to φ60°, the paper feeding speed was set to 400 k, the toner mass was formed on a paper weighing 80 V, and the fixing property was investigated, and the pressure contact area was 11
In case (2), good fixing properties were obtained at 140° C. and the image quality was also good.

Next, when I made copies continuously at a speed of 64 sheets/A3・minute, (oil application amount 2.5g/m2・1 sheet)
I made 200,000 copies and had no problems at all. In addition, assuming that dust gets into the coating layer and the roller,
I rotated it with μ particle size iron powder in between, but no scratches occurred.

In the above experiment, the coating film thickness (surface thickness) during molding of the heating roller and the firing temperature were variously changed. It became rough, resulting in an unfavorable result as a heat fixing roller.

Next, when the firing temperature was lower than 250° C., toner adhered to the surface of the heating roller after 50,000 sheets were passed, resulting in a black stain. This is because if the firing temperature is low, the surface layer will contain too much fluorine rubber, and the properties of the fluorine rubber itself will largely control the properties of the roller, resulting in poor mold releasability.

Conversely, when the firing temperature becomes high, the fluorocarbon resin becomes excessive on the surface of the molded product, which improves mold releasability.However, when the firing temperature exceeds 400℃, the fluorocarbon Due to the heat resistance limit of fluorocarbon resin, it becomes difficult to achieve the desired heating roller properties.

Next, as a comparative example, when using a rope coated with 80W thick PFA or polytetrafluoroethylene PTFFn on the surface layer of a rigid roller with an internal heating stage,
The temperature at which good fixing performance was obtained under the same conditions as above was 165° C., which was significantly higher than the 140° C. of this example. The reason for this is the 5K mentioned above.

This is thought to be largely due to the difference between the elastic body and the rigid body, which explains the unique effects of this embodiment.

Further, similarly to the above, when a sooting heating roller of PFA or PI'FPf was used to sandwich iron powder, the heating roller was scratched in a linear manner, resulting in poor fixing at that location.

This is because, in the case of an elastic body that has both rigidity and elasticity, as in this example, even if a local force is applied, a force acts to absorb and disperse the force, but PFA, PI'FE
In the case of a rigid body such as a coated heating roller, it is thought that it is damaged because it is directly subjected to partial stress due to frictional force caused by the gold powder.

The table below shows the results of examining the scratch resistance of this example and this coated heating roller using other methods. This is done by applying a constant load (0.15w) to a ballpoint pen and scanning the roller, then measuring the depth of the scratches with a surface roughness needle (using Koita Institute's 8g-RoC universal surface profile measuring device). It was measured in The coating thickness of the surface layer was all 80μ.

That is, from the above values, although the roller of the present embodiment changes somewhat depending on the surface temperature, there is no major change. On the other hand, the rigid PFA rollers and Prn rollers described above exhibit extreme fluctuations in response to temperature changes, and the depth of scratches is more than 1.5 times that of this example, and in most cases is 6 times as deep. It is occurring.

Therefore, the heating roller of this example exhibits durability that is several orders of magnitude better, and also has strength that is several orders of magnitude better than the conventional rollers against foreign objects such as metals.

The above description has explained the features of this embodiment with respect to the rigid p-roller. Next, the features of this embodiment that are superior to the elastic so-called rubber roller will be explained.

As a comparative example, if a hollow metal roller coated with a silicone rubber layer of 0.5 m thick is used, the temperature at which good fixing performance can be obtained under the same conditions as above is as follows. The temperature was 140°C as in this example.Next, when iron powder was sandwiched in the same manner as above, due to its large elastic force, there were slightly fewer scratches than in this example.However, in terms of resistance and entry surface. The following defects were found: 50,000 copies.

When the roller was beaded, the outer diameter of the heating roller became uneven and easily wrinkled, and toner offset was also likely to occur. When copying was continued and around 78,000 sheets were copied, the silicone rubber core separated from the hollow metal roller and the roller was damaged. That is, a simple rubber roller could not provide the durability that can be used for a long period of time while maintaining fixing properties as in Example 5.

As described above, 1. With the heat fixing roller to which the present invention is applied, it is possible to complete a long-life fixing device that has good fixing properties, achieves energy saving, and maintains stable performance over a long period of time. did it.

In the embodiment shown in FIG. 1 above, the present invention was applied to the heat fixing roller, but the present invention can also be applied to the pressure roller 2 that presses against the heating roller 21, or both. It can be applied to the surface of a rotating body such as a pressure fixing roller or a conveyor belt used in a fixing device. Several examples will be briefly explained below in Figure 2.6.

@2 Figure is an explanatory diagram of an embodiment in which the present invention is applied to the pressure roller 2 of Figure 1. In general, the surface layer of the pressure roller 20 rarely comes into direct contact with the unfixed 1lis, and it is sufficient that its surface temperature is relatively low, such as about 100 degrees Celsius or 80 degrees Celsius. The pressure roller 2 is rarely provided with a heating source 51, and what is required of the pressure roller is appropriate elasticity, heat retention on the surface, and durability.This embodiment takes the above points into consideration. The metal hollow roller 6 has a heat source 51 therein that supplies relatively low heat, and has a surface layer 4 made of fluororesin and fluororubber coated thicker than the heating roller 1 on the surface of the metal hollow roller 6. The thickness is the same as the elastic roller with a rubber layer of about 0.51 mm, or thicker than the heating roller 1, and the temperature at the time of molding is 25 to 400 degrees Celsius.
The temperature may be higher than or equal to 400° C., but the mold releasability may be improved at 400° C. or higher.

FIG. 6 shows a pressure roller 21 without a heat source, which is applicable to a pressure fusing device and used as a pressure roller of a heated fusing roller.

This roller 21 is constructed by providing a relatively thick elastic rubber layer 71 on the jI6 side of the metallic roller core 6, and surrounding the rubber layer 71 with a low layer of polytetrafluoroethylene tube. This roller 21 has an excellent effect as a roller that comes into pressure contact with the heating roller 1 shown in FIG.

The rope configured without the heat source of the heating roller 1 is used as a pressure roller on the side that comes into contact with the toner image, and the pressure roller 21
Even if a pressure fixing device is configured in which the fixing device is brought into pressure contact with the fixing device, it maintains excellent fixing performance and is highly durable.

As described above, the present invention can provide an excellent fixing device that is durable and can be used for a long period of time while maintaining fixing performance.

[Brief explanation of the drawing]

@Figure 1 is an explanatory diagram of an embodiment of the present invention, and Figure 2 is an explanatory diagram of an embodiment of the present invention. Figure 3 respectively. It is an explanatory view for explaining other examples of the present invention. 1 is a heating roller, 2.21 is a pressure roller, 6 is a hollow roller core, 4 is a surface layer, 5.51 is a heater, 6 is a metal roller core, 7 is a silicone rubber roller, 8 is a temperature sensing element, 15 is a control means.

Claims (1)

[Scope of Claims] 0) A supporting material for supporting an unfixed image @1. In the fixing device which fixes the unfixed image to the support material by conveying the unfixed image between two rotating bodies, at least the first rotating body has a surface layer having a mixture of fluororubber and fluororesin. The fixing device according to claim 1, characterized in that the fixing device has the following features: (5) The surface layer is formed by applying a mixture of fluororubber, fluororesin, compounding agent, and curing agent dispersed in water or a solvent to the core material of the first rolling body, and then baking at 25°C to 400°C. Claim 1 characterized in that the product is molded as
The fixing device according to item or @ item 2.