JPH06100876B2 - Fixing roller and fixing device having the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is applied to image forming apparatuses such as copiers, printing machines, printers, and composite recording apparatuses in general. And a fixing device having the same.

Conventionally, in the roller fixing device, the surface layer of the fixing roller is
A release material such as RTV silicone rubber or Teflon (trade name; DuPont) was provided, and in some cases, a release agent such as silicone oil was applied to prevent offset. The one where the surface of the fixing roller is covered with RTV silicone rubber generally does not need to be coated with a release material,
The device is simple, and due to the elastic force of silicon rubber,
Although the fixing property was good, the releasability changed significantly over time (deterioration), the life was very short, and the rollers had to be frequently replaced. If a mold release agent such as silicone oil is applied to maintain the mold releasability, the silicone rubber will swell with the silicone oil and the physical strength will decrease, so the rollers must be frequently replaced. .
Also, a roller whose surface is coated with a fluororesin such as tetrafluoroethylene-fluoroalkoxyethylene copolymer resin (hereinafter referred to as PFA) or polytetrafluoroethylene resin (hereinafter referred to as PTFE) is compared with the above silicone rubber. And has high strength, and if silicone oil is applied, the releasability is also good.

However, since the roller does not have elasticity, the fixability is poor as compared with the silicone rubber roller, and the effect of crushing the image when fixing the toner image on the toner image support is large,
It has the drawback of degrading image quality. Further, when there is an abutting object such as a cleaning plate on the roller, and when hard dust adheres to the roller and enters between the roller and the abutting object, there is no elasticity and there is no place for the force to escape.

The above-mentioned difference in fixing property is caused by the unevenness of the support material in the case of an elastic body such as silicon rubber, and the shape of the fixing roller that follows the unevenness of the toner image on the support material, so that the entire surface contacts uniformly. It is considered that the fixability is excellent.

However, in the case of a rigid body such as Teflon (trade name; DuPont), the convex portion makes strong contact with the roller and the concave portion makes unstable contact with the roller due to the unevenness of the support material and the toner image. It is considered that the fixing of the recesses becomes very weak. From the experimental results, it is known that silicon rubber can be fixed at a temperature 20 to 50 ° C lower than that of Teflon to completely fix the same toner image.

Further, JP-A-48-85151 discloses a fixing roller in which tetrafluoroethylene resin powder and silicone raw rubber are mixed. In this case, the compatibility between silicon and Teflon is poor and the dispersibility is poor, and the adhesiveness is low. Therefore, there are many problems that the strength is very weak, and that when a mold release agent such as silicone oil is applied, the silicone rubber swells due to the oil swelling and the physical strength is greatly reduced.

Further, as described in JP-A-58-5770, a rubber layer is provided on the outer periphery of the fixing roller, and the elasticity of the rubber layer is improved by applying a mixture of fluororubber and fluororesin to the surface of the rubber layer. A fixing roller having the releasing stability of a fluororesin has been proposed. In the case of this type of fixing roller, a large amount of fluororesin is present on the surface layer of the fixing roller to obtain releasability, but this fluororesin layer generally contains a mixture of fluororubber and fluororesin at 260 ° C to 350 ° C. Firing is performed, but in this case, the thickness of the surface fluororesin layer is only 2 to 3 μm at most, and the support material passing through the fixing roller is abraded, and is abraded by contacting objects such as separating claws and cleaning members. Therefore, it is difficult to maintain the release layer for a long time.

Further, if the thickness of the fluororesin layer is made to be 2 to 3 μ or more, the sintering condition is, for example, 400 ° C. or more, and the firing time is 1 hour or more, so that the lower rubber layer is not significantly deteriorated. However, there are drawbacks such as the complexity. Moreover, even in such a case, the thickness of the fluororesin layer is no more than about 5 μm.

SUMMARY OF THE INVENTION The present invention provides a fixing device including a fixing rotator that solves the above-mentioned conventional drawbacks and has a superior fixing effect.

Another object of the present invention is to provide a fixing device having good releasability, fixability and strength over a long period of time. To achieve the above object, the present invention provides a roller base, a silicon rubber layer provided on the roller base, and a mixed layer having a rubber and a resin provided on the silicon rubber layer,
And a resin layer provided on the mixed layer.

Further, according to the present invention, in a fixing device having a fixing roller for fixing an unfixed image on a recording material, the fixing roller comprises a roller base, a silicone rubber layer provided on the roller base, and a silicone rubber layer. It is characterized in that it has a mixed layer having a rubber and a resin provided on the rubber layer, and a resin layer provided on the mixed layer.

Furthermore, the present invention is provided with a roller base, a silicone rubber layer provided on the roller base, a mixed layer having rubber and resin provided on the silicon rubber layer, and a mixed layer provided on the mixed layer. It is characterized by having a resin layer having a relatively low melting temperature and a resin layer provided on the resin layer and having a melting temperature equal to or higher than the resin layer.

Furthermore, the present invention relates to a fixing device having a fixing roller for fixing an unfixed image on a recording material, wherein the fixing roller comprises a roller base, a silicone rubber layer provided on the roller base, and A mixed layer having a rubber and a resin provided on the silicone rubber layer, a resin layer having a relatively low melting temperature provided on the mixed layer, and a resin layer provided on the resin layer or equivalent to And a resin layer having a higher melting temperature.

FIG. 1 shows a sectional view of a fixing roller A according to a first invention example of the present invention. The fixing roller A has a rubber layer 2b after thermal vulcanization adhered to a hollow cylindrical metallic substrate 3 with a primer, and a layer 2a made of a mixture of fluororubber and fluororesin is placed on the rubber layer 2b. It is applied, and the fluororesin layer 1 is coated thereon.

The fixing roller A is obtained as follows.

The rubber layer 2b of the roller A is fixed to the metallic substrate 3 in a state where it is subjected to thermal vulcanization such as primary vulcanization and secondary vulcanization to obtain general rubber elasticity.

A mixture of fluororubber and fluororesin (for example, fluororubber water-based paint: Daiel GL213, trade name, Daikin) is applied on the rubber layer 2b to a thickness of 20 μm by a spray gun or the like and heated at room temperature or an infrared heater. To dry. Then, it is dried with hot air at a temperature of 150 ° C. At this time, on the surface of the mixture of fluororesin and fluororubber,
The water repellency of fluororesins is not very high. Emulsion PFA resin is applied on top of this to a thickness of 10μ. Then, the first baking is performed at 260 ° C. for 15 minutes. At this time, the mixture of the fluororesin and the fluororubber applied between the rubber layer 2b and the PFA resin layer 1 becomes the fluororesin due to the Brownian motion of the fluororesin.
It floats on the PFA resin layer 1 side, and at the same time, crosslinking of the fluororubber component proceeds. Furthermore, this heat treatment results in the lower rubber layer
It is possible to prevent depolymerization of 2b.

Further, the fluororesin floating on the PFA resin layer 1 side is well compatible with the PFA resin and the adhesive strength is increased.

After this step, final baking was performed at 350 ° C for 30 minutes, and PFA on the surface layer
The resin layer is melted and completely adhered to make the surface smooth. The PFA resin layer may be coated in the PFA resin powder state and electrostatically coated.

If ultra-heat-resistant fluororubber or silicone rubber that does not deteriorate even at a high temperature of 300 ° C. or higher is used as the lower rubber layer, the final firing step can be performed without performing primary firing.

The fixing roller thus obtained has a release layer of fluorocarbon resin having a thickness of 10 μm or more on the surface layer, and the elasticity of the lower rubber layer 1 is not lost in the fluorocarbon resin layer having a thickness of about 10 μm. It becomes a fixing roller.

In FIG. 2, the fixing roller A of the embodiment shown in FIG. 1 is used as a heating roller A ′ that contacts the toner image. FIG. 2 shows an example of a fixing device used in a recording apparatus, which is a heating roller A '.
Metal base 3, primer (not shown), elastic rubber layer 2b,
As the mixed layer 2a and the fluororesin layer, those mentioned above were used. Here, the fluororesin layer uses PFA resin.

The heating roller A ′ has a heater 4 inside the cylindrical base body 3.
By means of a detection member 6 (contact type in this example) for detecting the surface temperature of the roller A ′ and the temperature control means 5.
The temperature (for example, 180 ° C. to 200 ° C.) necessary to fix the toner image T on the paper P as a recording material is maintained. The pressure roller B is brought into pressure contact with the heating roller A ′ by a pressure means (not shown), and the paper P is nipped and conveyed together with the heating roller A ′. The pressure roller B has a heat resistant elastic layer 17, for example, a silicone rubber layer, on a metal core 18 having a cylindrical shape.

Reference numeral 7 denotes a cleaning web impregnated with a mold release liquid such as silicone oil or fluorine oil, which is a winding shaft 9 and a supply shaft 8.
Also, it is moved by the pressing roller 10 intermittently or at a relative speed to the heating roller A '. By this movement, the surface of the heating roller A ′ is ground with the offset toner and the release liquid for offset prevention is supplied.

A conveyor belt 12 guides the paper P having a toner image T formed on one surface thereof by a predetermined image forming means to the pressure contact portion between the guide plate 11, the heating roller A ′ and the pressure roller B. 13 is a separation claw for separating the paper P by the heating roller A ', and 14 is a separation claw for separating the paper P by the pressure roller B, which are in contact with the respective roller surfaces. Reference numerals 15 and 16 are a pair of discharge rollers for discharging or sending to another part. Each arrow in the figure indicates the rotation or movement direction of each member.

As described above, the heating roller A'because the rubber layer 2b has rubber properties, and then the mixture 2b of fluororubber and fluororesin is provided on the rubber layer 2 to serve as a primer for the surface fluororesin layer. Since the fluororesin layer having a good releasability is coated on the rubber layer 2 with a sufficient thickness so as not to lose elasticity, the rubber layer 2 has appropriate strength and elasticity.

Therefore, the toner image is heat-fixed on the paper P as an image having good image quality and good fixing property in every detail. Moreover, at that time, the toner image can be largely prevented from being offset to the heating roller A ′.

Therefore, in the mold using the web 7 as in this example, the consumption of the web as the cleaning member can be reduced and the release liquid can be supplied to prevent the offset.

At the same time, since the release layer of the heating roller A ′ itself has a sufficient thickness, it can be put to practical use that can withstand abrasion of the surface layer due to long-term use.

Table 1 shows that the heating roller A'is directly coated with PTFE, PF on a metallic substrate.
A, FEP, etc. coated with a fluororesin, a mixture of fluororubber and fluororesin is coated on the rubber layer, and it is 300 ℃
It is baked for 30 minutes at 30 minutes and the fluororesin is floated on the surface.
Furthermore, the wear states of the fluororesin layers on the respective surface layers of the above-mentioned embodiment of the present invention are shown.

In the results shown in Table 1, the fixing device having the structure shown in FIG. 2 was used, and the heating roller A'and the pressure roller B were used.
The diameter is 40 mm, the recording paper conveyance speed is 210 mm / sec, and A4 horizontal feed is used at a rate of 30 sheets per minute, and a total of 50,000 sheets have been passed.

On the other hand, in a heating roller in which a rubber layer and a layer made of a mixture of fluororubber and fluororesin are formed on a metallic substrate, the fluororesin layer, which is the release layer of the surface layer, has a thin thickness of 2.5 μm, and in the surface layer and near the surface layer, Since the fluororubber having a poor releasability is scattered, the releasability is immediately deteriorated due to a slight deviation of the surface layer. Therefore, the fixing property is good due to the elasticity of the lower rubber layer, but the durability is very poor. Further, if the operating temperature is raised to 200 ° C, the durability will be extremely reduced probably because the heat resistance of the surface fluororesin layer is poor.

The heating roller provided with a rubber layer on the cored bar, a fluororubber and a fluororesin mixture thereon, and a fluororesin (PFA in this example) layer on the cored bar of the present embodiment has operating temperatures of 180 ° C. and 200 ° C. Both of them exhibit excellent durability, and excellent fixing properties can be obtained due to the elasticity of the lower rubber layer.

In addition, the wear amount of the fluororesin layer is the same between the one in which the PFA layer is directly provided on the metallic substrate at the operating temperature of 200 ° C and the one in which the rubber layer, the fluororubber, the fluororesin mixture layer, and the PFA layer are sequentially provided. Regardless of the difference in durability, the former PFA roller has a PFA film thickness of 2.5μ. As can be seen in Table 1, generally, a metal substrate (indicated by a core metal in the table) directly coated with a fluororesin such as PTFE, PFA, FEP is inferior in fixing property to the elastic roller. Regarding durability (refers to the offset property when the paper does not wrap around the heating roller when it is passed), the operating temperature is 120 ° C.
Then, PTFE, PFA and FEP all have more than 250,000 sheets.

At 200 ℃, PFA and FEP have slightly lower heat resistance than PTFE, so the durability is reduced to 200,000 sheets for PFA and 150,000 sheets for FEP.

In reality, it is considered that there is a portion where the metal portion protrudes close to the surface layer due to the unevenness of the core metal, and the releasability decreases at this portion. On the other hand, it is considered that in the heating roller to which the present invention is applied, the unevenness of the metallic substrate is absorbed by the rubber layer, and the outermost PFA layer has a substantially uniform thickness.

Regarding specific numerical examples of the present invention, it is desired that the thickness of the lower rubber layer is 0.1 to 2 mm, preferably 0.2 to 1.0 mm from the viewpoint of elasticity and thermal conductivity. For the lower rubber layer, silicone rubber, fluororubber, EPDM, etc. are desirable from the viewpoint of heat resistance, and carbon black or a good thermal conductor such as nickel oxide, titanium oxide, cobalt oxide or other metal oxide is mixed inside the rubber. By so doing, the thermal conductivity is increased and the adhesion to the upper layer fluororesin and fluororubber mixture is also increased.

The mixture of fluororubber and fluororesin provided on the rubber layer 2b has a thickness of 5 to 100 μ, preferably 5 to 30 μ. Has less unevenness, and the adhesiveness with the outermost fluororesin becomes good.

The fluororesin of the outermost layer is preferably a resin having good releasability such as PTFE, PFA and FEP. Further, the thickness of 3 μ to 100 μ, preferably 5 to 30 μ makes use of the elasticity of the lower rubber layer,
Further, a fixing roller having excellent long-term durability can be obtained.

In the sintering process, when PFA resin is used, a firing time of 15 minutes to 1 hour at a temperature of 320 ° C to 400 ° C is desirable. More preferably, it is desirable to carry out the primary firing at a temperature of 240 to 280 ° C. before the firing step to heat treat the rubber layer 1 to prevent depolymerization.

Hereinafter, another embodiment of the present invention will be shown.

1. In FIG. 1, the lower rubber layer 2b is coated with a heat resistant rubber such as silicone rubber, fluororubber or EPDM, and the mixture 2a composed of fluororubber and fluororesin is applied onto the rubber layer by a spray gun or the like. It is applied in a thickness of 10μ, dried at room temperature or while being heated by an infrared heater, etc., and then dried with warm air at 150 ° C. Further, FEP resin in an emulsion state is applied on this layer to a thickness of 10 μm. After that, baking is performed at 260 ° C. for 30 minutes to form the FEP resin layer 1 on the outermost layer. As described above, the FEP resin melts at a relatively low temperature and has a low melt viscosity, so that it easily flows during firing.
Therefore, when the fluororesin / fluororubber mixture layer 2a is fired,
If the fluororesin floats on the surface side, it is easy to slip in if it becomes uneven as a result of the phenomenon that it floats on the surface side, and it has excellent even adhesion. Since it can be fired at a lower temperature, it has an advantage that the lower rubber layer is not deteriorated. In order to further strengthen the adhesiveness, it is also very effective to dry the fluororubber and fluororesin layers with hot air and then roughen the surface.

2. PTF instead of the PFA resin used in the first embodiment of the present invention
Even if E resin is used, the fixing roller can be manufactured under the same manufacturing conditions. The action and effect at this time are almost the same as those of the PFA resin, but show better characteristics in heat resistance than the PFA resin.

3. In FIG. 1, the lower rubber layer 2b is coated with a heat-resistant rubber such as silicone rubber, fluororubber or EPDM, and the mixture 2a made of fluororubber and fluororesin is applied onto the rubber layer by a spray gun or other application means. It is applied to a thickness of 10 μm and dried at room temperature or while being heated by an infrared heater or the like, and then hot air drying at 150 ° C. is performed. Further, FEP resin in an emulsion state is applied on this layer to a thickness of 5 μm. After that, baking is performed at 260 ° C. for 15 minutes to form an FEP resin layer.
Further, a powdered PFA resin is applied on the FEP resin layer by electrostatic coating so as to have a thickness of 10 μm, and baked at 300 ° C. for 30 minutes. In this way, a PFA resin layer having excellent heat resistance is formed on the outermost layer. It has the characteristics of low melt viscosity and easy flow.
By covering the FEP resin layer on the fluororubber and fluororesin layers, the surface is made even and the heat resistance is excellent.
Further, by forming a PFA resin having a higher melting temperature than that of the FEP resin on the surface layer, excellent bonding strength can be obtained, and the fluororesin of the surface layer can be made sufficiently thick.

Also, the same effect can be obtained by using PTFE resin for the outermost layer,
Especially in the case of PTFE resin, it does not melt completely even at high temperature and there are many pinholes and the unevenness is severe, so the surface area becomes large and the FEP resin flows into the unevenness and shows excellent adhesion, so it is very A strong product can be obtained.

As described above, since the present invention has the mixed layer of fluororubber and fluororesin as the intermediate layer, the rubber layer of the lower layer and the resin layer of the upper layer are firmly bonded to each other to increase the surface resin thickness. It was possible to provide a roller having elasticity and excellent durability and wear resistance. Therefore, it also has an advantage that the fixing property is good and the image quality is also very excellent.

[Brief description of drawings]

FIG. 1 is a sectional view of a fixing roller that is an embodiment of the present invention, and FIG. 2 is a sectional view of a fixing device to which the roller of the present invention is applied. 1 is a resin layer, 2a is a mixed layer, 2b is an elastic layer, and 3 is a substrate.

Claims (4)

[Claims] 1. A roller base, a silicone rubber layer provided on the roller base, a mixed layer containing rubber and a resin provided on the silicone rubber layer, and a resin provided on the mixed layer. A fixing roller having a layer. 2. A fixing device having a fixing roller for fixing an unfixed image on a recording material, wherein the fixing roller is a roller base, a silicon rubber layer provided on the roller base, and the silicon. A fixing device comprising: a mixed layer having a rubber and a resin provided on a rubber layer; and a resin layer provided on the mixed layer. 3. A roller base, a silicone rubber layer provided on the roller base, a mixed layer having rubber and resin provided on the silicon rubber layer, and a comparison provided on the mixed layer. A fixing roller comprising a resin layer having a low effective melting temperature and a resin layer provided on the resin layer and having a melting temperature equal to or higher than the resin layer. 4. A fixing device having a fixing roller for fixing an unfixed image on a recording material, wherein the fixing roller is a roller base, a silicon rubber layer provided on the roller base, and the silicon. A mixed layer having a rubber and a resin provided on the rubber layer, a resin layer having a relatively low melting temperature provided on the mixed layer, and a resin layer provided on the resin layer, which is equal to or more than the resin layer. And a resin layer having a high melting temperature.