JPH0136624B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fixing rotating body used for fixing an unfixed image and a fixing device having the same.

Conventionally, as a device for fixing this type of unfixed image, a fixing roller, a pressure contact (or pressure) roller, etc. that are in pressure contact with the fixing roller have been frequently used. The following three items are installed on this pressure roller side.
They can be roughly divided into different types, each of which has drawbacks as described below.

In the first case, a primer is coated on the core metal and a silicone layer or the like is thickly provided on the surface, that is, a uniform elastic layer is provided on the roller base. In this type of roller, oil, additives, etc. must be added to reduce the elasticity of the elastomer, such as rubber, resulting in changes in the mechanical and physical properties of the elastomer. Therefore, the hardness cannot be made too low while maintaining its properties. or,
The pressure contact area obtained with the support material that supports the toner image formed by electrophotography etc. is small and the amount of heat that can be applied per unit time is small, and it is often used as an elastic layer. It requires a large amount of materials such as rubber,
In addition, it is uneconomical and requires a long waiting time to heat the entire elastic layer, which increases the fall of the initial roller surface and causes insufficient fixing. Moreover, the method of increasing the number of heaters to prevent this is uneconomical.

In the second case, a fixing roller is formed by coating a core with a primer and further providing a porous member made of silicone rubber. The disadvantages of this roller are that the surface of the fixing roller is not smooth, which reduces fixing performance, and when a release agent is applied, a large amount of release agent is contained in the porous material, causing damage to the porous member itself. tends to deteriorate, and its durability is inferior to that of solid.

In the third case, two elastic layers are added to improve oil resistance.
There are those with multi-layered or triple-layered structures. However, when a large number of elastic layers are provided simply to improve oil resistance, the cost increases significantly due to the use of a large amount of elastic material as described above.

SUMMARY OF THE INVENTION The present invention aims to eliminate the drawbacks of the conventional fixing body and provides a fixing rotary body and a fixing device having the same, which were invented in consideration of being cheaper and saving resources.

That is, the first invention of the present application is a fixing rotating body that rotates in contact with the back surface of a support material that supports an unfixed image, and includes a rotating shaft, a heat-resistant elastic material surface layer, and a heat-resistant elastic material surface layer. a heat-resistant porous elastic layer having a large number of air bubbles, the heat-resistant porous elastic layer being thicker than the heat-resistant elastic surface layer and substantially in contact with the heat-resistant elastic layer; The second invention of the present application provides a fixing device having a pair of rotating bodies that heats and fixes an unfixed image on a support material by sandwiching and conveying a support material that supports the unfixed image. A rotating body that rotates in contact with the back surface of the support material that supports the printed image is provided with a rotating shaft, a heat-resistant elastic surface layer, and substantially in contact with the heat-resistant elastic surface layer, and is provided with a heat-resistant elastic surface layer. The fixing device is characterized in that it has a heat-resistant porous elastic layer that is thicker than the body surface layer and has a large number of bubbles.

Hereinafter, the present invention will be explained with reference to the drawings. FIG. 1 is a schematic side view of one embodiment of the invention. 1 is a heating fixing roller;
A Teflon (registered trademark) coating layer 6 is provided on the surface of a metal roller 5 having a heating means 4 inside. 2 is a pressure roller that comes into pressure contact with the heat fixing roller 1, and a one-component liquid is placed on the core bar 7 that is the central axis of rotation.
Apply RTV silicone rubber primer 7 ₂ , and on top of that a sponge layer 8 made of silicone sponge.
It has an elastic coating layer 9 which is made by adhering and further coating RTV silicone rubber. The surface of the pressure roller 2 is generally coated with RTV (room temperature vulcanization type) silicone rubber and then polished to adjust the shape of the roller.

Further, the Teflon (registered trademark) coating layer 6 of the heat fixing roller 1 is coated with a cleaning means such as Cleaning Grade 16 and an anti-offset liquid applying means 3 (as shown in the figure) as described in Japanese Patent Application Laid-open No. 144268/1983. (having a silicone oil impregnated member 10, a damage prevention member 12, and a continuous porous member) are in contact with each other.

Furthermore, the pressure roller 2 is provided with a means for making the state of pressure contact with the heat fixing roller 1 variable; for example, an arm that supports the rotation of the core bar 7 and makes the position of the core bar 7 variable along with the attachment point ₇₁ . 17 and the point 17 that is the center of rotation of arm 17 ₁ and arm 17
A cam means 18 for changing the position as shown by the solid line arrow is provided as shown in the figure.

Now, the paper P having the toner image T formed by a predetermined image forming means is transferred to the transport roller pair 14.
The belt 15, which is hung on the belt 15, moves and is conveyed. Next, the paper P is transferred from the belt 15 to the guide member 13 and guided to the wide pressure contact area formed by the heating and pressure rollers 1 and 2.

On the other hand, in the wide pressure contact area, the layer 6 is uniformly heated by the heating means 4, and the elastic coating layer 9 is uniformly heated by the conductive heat from the heat fixing roller 1.
As for the pressure roller 2, due to the above structure, the coating layer 9 has higher thermal conductivity than the sponge layer 8. The time required to achieve this goal has been significantly shortened. Furthermore, since the sponge layer 8 has a large volume occupied by gas such as air in addition to the sponge component,
The thermal conductivity of this sponge layer 8 is poorer than that of the covering layer 9. In other words, the amount of heating required by the heat fixing roller 1 to maintain the entire pressure roller 2 itself at a predetermined temperature is only a small amount compared to conventional ones, and a large amount of heat is not wasted on other things. Since there is no heat, its thermal efficiency has been greatly improved, making it highly efficient. Furthermore, even if the apparent hardness of the roller surface is the same, the above embodiment having the sponge layer 8 is more easily deformed than a single solid material, and the pressure contact area between the rollers can be made wider.

Therefore, even if the amount of heat generated by the toner is the same per unit time, heat can be applied to the toner image (or paper P) because the toner can be in contact with the toner for a long time.

Next, when the paper P enters the wide pressure contact area, the toner image supported by the paper P is permanently fixed to the paper P by uniform heat from above and below. In this case, although the paper P, which is an example of the support material, has not been processed into an inverted crown shape, etc., which is generally used as a treatment for wrinkles that tend to appear during fixing, It had not occurred at all.

Next, the excellent effects of the embodiments of the present invention will be explained by statistically evaluating the results of the above embodiments.
In the following experiment, the outer diameter of the roller was 25φ, and (1) its composition was a silicone sponge layer of 6 mm thickness and a rubber layer of 1 mm thick.
(2) one with a double structure with a thick layer and the other with a single structure with an elastic layer consisting of only a 7 mm thick silicone rubber layer, both under the same conditions that the surface hardness in the roller form is JIS-A6°. I went. Then, this roller was placed opposite a Teflon (registered trademark) coated roller having an outer diameter of 25φ and pressed with a constant pressure, and the change in the amount of nips and the incidence of wrinkles at that time were examined.

As a result, when using the roller 1 according to the present invention, the pressure contact width was 4.6 mm when 4 kg of full pressure was applied, and the occurrence of wrinkles was 0.15% or less when 1000 sheets of A4 size paper were continuously copied. Ta. However, when using the conventional roller 1, the total pressure is 1
Similarly, when 4 kg of pressure is applied, the pressure welding width is as small as 2.7 mm, and similarly to 1, when 1000 sheets of A4 size paper are continuously
The occurrence of wrinkles when copying a sheet is always 0.7 to 1%.
It was within the range of

Also, when comparing the fixing properties according to the above experimental comparison,
Constant pressure during continuous copying (3.5 kg or more at full power)
If the temperature is constant (175℃ or higher), the product of pressure and temperature per unit time is almost equal, although there is a pressure difference per unit area, so the conventional method (2)
Except for the above-mentioned example (1) achieving higher image quality, no particular difference could be found between the two because of the stable condition of continuous copying.

However, in the initial state when fixing is started and in the device that brings the fixing (heating) roller and the pressure roller into contact with each other every time fixing, the above example (1) according to the present invention provides exceptional fixing performance and high quality. I was able to obtain an image with

As described above, by using the above-mentioned embodiment according to the present invention, that is, the double-structure fixing roller having a silicone rubber layer on top of a sponge layer, the following many advantages can be obtained. It became possible.

In other words, since the heat conduction of the lower roller is extremely poor due to the sponge layer, there is little drop in roller surface temperature immediately after waiting up, making it possible to prevent the deterioration of fixing performance during waiting up, which could not be solved in the past. .

Furthermore, in order to manufacture the roller as described above,
The amount of rubber used was reduced by about 1/2, contributing to resource conservation and cost reduction.

In addition, since the contact pressure between the pressure roller and the fixing roller is reduced, a large and uniform pressure contact area can be obtained, so the driving torque can be reduced, and damage caused by compression set of the rubber roller can also be reduced. Ta. Also, when a roller is formed from a single layer of silicone sponge and used for fixing, the air bubbles create areas with good fixation and areas with poor fixation, which is undesirable and requires surface smoothness. I understand.

Therefore, we conducted further experiments and investigated the thickness of the silicone surface layer by varying it from 0.3 mm to 5 mm, but if it was too thick, the effects of the sponge layer, which is rich in elasticity and multiplicity, could not be used effectively. Also, if it is too thin, it will increase the strength and manufacturing cost, and it will also affect the stability, so it is preferably 0.5 mm.
A thickness of between 2 mm and 2 mm is suitable, more preferably
I found that 0.7 to 1 mm is suitable for the iron. (However, for a roller diameter of 25φ) In addition, as another example of the above example, in addition to the method of covering the sponge tube to form a silicone sponge layer, there is also a method of covering the sponge tube around the general core metal. A method may also be used in which rubber is spread and then heated.

Alternatively, as a method of manufacturing at a low cost, it is possible to cover the tube with a silicone rubber tube, place it in a mold, and then pour NUR (low temperature vulcanization type) silicone rubber between the sponge layer and the mold using the in-die injection method. In this case, due to the precision of the release surface of the mold, there is no need for final polishing and it is suitable for mass production.

On the roller base, there is a layer made of a material with poor thermal conductivity and high elasticity, such as a silicone sponge layer or a porous layer made of fluororubber, and a thin layer of elastic material such as silicone rubber, and a layer of elastic material such as a thin layer of silicone rubber is provided on the surface. ,2
The layered structure makes it possible to provide a roller that has a large heat capacity, a rich surface smoothness, and can form a uniform and constant nip width with low contact pressure, eliminating the problems of conventional rollers. At the same time, it has become cheaper, more resource-saving, more tolerant of paper wrinkles, and allows for a wider error range in assembly accuracy.

As explained above, the present invention is a fixing device that has good fixing performance during start-up, can be freely elastically deformed, maintains high image quality resulting from exceptional fixing performance, and has an extremely high wrinkle prevention effect. This is an economical and resource-saving fixing device that eliminates the need to add a filler as in the past, does not deteriorate the physical properties of the structure itself, and is easier to manufacture.

[Brief explanation of drawings]

FIG. 1 is a schematic side view of one embodiment of the invention. 1 is a heat fixing roller, 2 is a pressure roller, 7
8 is a tube, and 9 is an elastic coating layer.

Claims (1)

[Scope of Claims] 1. A fixing rotating body that rotates in contact with the back side of a support material that supports an unfixed image, which comprises a rotating shaft, a heat-resistant elastic surface layer, and the heat-resistant elastic surface layer. 1. A fixing rotating body comprising: a heat-resistant porous elastic layer having a large number of air bubbles, the heat-resistant porous elastic layer being thicker than the heat-resistant elastic surface layer, the heat-resistant porous elastic layer being substantially in contact with the heat-resistant elastic surface layer; 2. A fixing device having a pair of rotating bodies that thermally fixes the unfixed image to the support material by sandwiching and conveying the support material that supports the unfixed image, of the pair of rotating bodies supporting the unfixed image. The rotating body that rotates in contact with the back of the supporting material is
a rotating shaft, a heat-resistant elastic surface layer, and a heat-resistant porous material having a large number of air bubbles, which is provided substantially in contact with the heat-resistant elastic surface layer, and is thicker than the heat-resistant elastic surface layer. A fixing device comprising an elastic layer.