JPH10141356A - Elastic rotor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an elastic rotor heightening fixing performance of a copying machine and a printer and obtaining high image quality without dazzling while being excellent in durability by interposing a cushioning layer for relaxing the expansion difference between layers, between an elastic layer and a fluororesin layer, and making the hardness of the cushioning layer higher than that of the elastic layer. SOLUTION: A silicone rubber layer with a hardness of JIS A in a range of 0.1 degree or more and 20 degree or less and a thickness in a range of 0.1mm or more and 10mm or less is formed as an elastic layer on the surface of a core body made of aluminum. A silicone rubber layer harder than the above- mentioned silicone rubber layer, with a hardness of JIS A 27 degree, for instance, is provided as a cushioning layer on the surface of the elastic layer. A fluororesin layer formed of polytetrafluoroethylene or the like is formed at an outermost layer by sintering. The thickness of the respective layers are set to elastic layer >= cushioning layer > fluororesin layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an elastic rotating body used for an image forming apparatus such as an electrophotographic apparatus and a laser beam printer. The present invention relates to an elastic rotating body suitably used as a fixing roller for heat fixing.

[0002]

2. Description of the Related Art In many cases in an image forming apparatus such as an electrophotographic copying apparatus, a conveying roller for conveying a sheet-like transfer material or a recording material such as paper along a predetermined course has a conveying property, a releasing property. Properties and durability are required. In particular, heat is applied to the unfixed toner image on the transfer paper, and the fixing roller, which must convey the transfer paper to a predetermined path while preventing the offset of the molten toner, has transportability under severe conditions. Release properties, abrasion resistance, fixability and durability are required. The elastic roller using silicone rubber or fluoro rubber has a heat fixing area because the nip point (contact point) is in surface contact by increasing the contact pressure with the rubber elastic pressure roller that is in contact with this fixing roller. Therefore, there is an advantage that heat fixing can be performed effectively.

Taking advantage of these advantages, elastic rollers are often used in so-called high-speed copying machines, color copying machines, printers, etc., which have a high copying processing speed. To prevent this, a roller in which the surface of a rubber elastic body is coated with a fluororesin or a fixing roller in which a fluororesin tube is coated are often used.

In particular, a color copying machine, a color laser beam printer, and the like need to mix and fuse yellow, magenta, cyan, or black copy toner and heat-fix the copy paper to form a two-layer or three-layer structure. Silicon oil is impregnated into the silicone rubber roller, and a small amount of silicone oil is applied to the fixing roller when fixing the image, and the release properties of the silicone oil are used to improve the image quality, improve the releasability, and prevent offset. ing.

[0005] Such a technique and method not only complicates a copying machine or a printer itself, but also complicates a copier or a printer itself, such as a silicon oil supply device or a waste oil processing part.
It also has many problems in terms of maintenance and component life.

In terms of image quality of color copying, parameters for image quality evaluation, such as fixing properties for melting and mixing a plurality of toners and fixing the same on transfer paper, or glossiness (shininess) and offset properties of a color image are considered. In addition, if the contact pressure (fixing pressure) between the fixing roller and the pressure roller is increased in order to improve the fixing property, the shininess of the color image is enlarged, and good color image quality cannot be obtained. Further, there is a contradictory problem that when the fixing pressure is weakened, the fixing becomes insufficient.

Therefore, in order to solve these problems,
Fixing and lowering the hardness of the elastic rubber of the pressure roller as much as possible, taking the nip width as large as possible when both rollers are contacted and pressed, performing thermal fixing with low fixing pressure, and at the same time, alleviating the shiny feeling In addition, a technique has been developed for improving the releasability and preventing offset by using a fluororesin layer as the outermost layer of the roller.

In the course of such research and development, in a fixing roller composed of a silicone rubber elastic layer and an outermost fluororesin layer, the lower the rubber hardness of the silicone rubber roller, the greater the deformation of the nip. In addition to the force applied, each layer cannot follow the dynamic movement at the interface between the silicone rubber layer and the fluororesin layer, causing fatal wrinkles on the surface of the fluororesin layer and failing to obtain a clear image. Will also affect the life of the device. In other words, in order to improve the fixing property of the toner, the nip area between the fixing and pressurizing rollers is improved by reducing factors such as lowering the hardness of the rubber elastic layer, increasing the rubber thickness, or increasing the fixing pressure. It is necessary to secure

However, improving the nip area as described above tends to increase the amount of deformation of the rubber elastic layer, and these factors cause a problem that wrinkles are generated in the fluororesin layer.

[0010]

When the surface of a silicone rubber elastic layer is coated with a fluorine resin in a state where the hardness of the silicon rubber elastic layer is high to some extent, the rubber elastic layer is excessively deformed even if the fixing pressure by the fixing roller and the pressure roller is high. In addition, since the fluororesin multi-layer follows the deformation amount, no wrinkles are generated.

However, when the hardness of the rubber elastic layer is constant, as the hardness decreases, the amount of deformation of the rubber elastic layer increases, and it is natural that the deformation of each layer at the interface between the fluororesin layer and the rubber layer. The movement will be different and lead to wrinkles. That is, at the interface between the rubber layer and the fluororesin layer, the rubber expands and deforms in proportion to the hardness and the fixing pressure, but since the fluororesin layer does not expand as much as silicon rubber,
Even when the fixing pressure is removed, a portion of the rubber surface where the rubber is to be restored is stopped by the fluororesin layer due to the difference between the elongation of the rubber layer and the elongation of the fluororesin layer, and remains in a wrinkle shape on the roller surface.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an elastic rotating body which is capable of improving the fixing property of a copying machine or a printer, and which is capable of obtaining a high-quality image without a shininess and having excellent durability. The purpose is to provide.

[0013]

In order to achieve the above object, an elastic rotating body according to the present invention is an elastic rotating body having an elastic layer on a surface of a core and a fluororesin layer on an outer layer, wherein the elastic layer is A buffer layer is provided between the fluororesin layers to reduce the difference in expansion and contraction of each layer, and the hardness of the buffer layer is higher than the hardness of the elastic layer.

In the above construction, the elastic body is silicon rubber, and the fluororesin is polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkylvinylether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer. It is preferably at least one fired layer selected from a polymer (PFEP) and a tetrafluoroethylene-ethylene copolymer. Of course, it may be a fired layer of the resin mixture.

In the above structure, the elastic layer preferably has a rubber hardness of 0.1 to 20 degrees in JIS A hardness and a thickness of 0.1 to 10 mm.

Further, in the above structure, it is preferable that the elastic layer ≧ the buffer layer> the thickness of the fluororesin layer. In the above configuration, the buffer layer is preferably an elastic body.

In the above structure, it is preferable that the buffer layer is at least one selected from silicone rubber, fluorine rubber and a mixture thereof. Further, in the above configuration, it is preferable that the thickness of the buffer layer is in the range of 0.1 mm or more and 3 mm or less.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The elastic rotating body of the present invention is an elastic rotating body having two or more elastic layers on the surface of a core and a fluororesin on its outer layer, and a first layer in contact with the core. When the second layer of the elastic body has a higher hardness than the elastic body and the first elastic layer has a large thickness, the first layer can be thermally fixed with a fixed fixing force. Rubber deformation is 2
It is absorbed by the elastic layer having high hardness of the layer, and does not reach the fluororesin layer of its exterior.

Therefore, when used as a fixing roller of a color copying machine or a printer, even if a fixing pressure required for heat fixing is applied, the fluororesin layer on the roller surface will not be wrinkled or destroyed. By using an elastic material having a low hardness for the layer, the fixing pressure can be lowered, the nip width is wide, and a sufficient fixed image without copy feeling can be obtained.

In the present invention, the elastic body is a silicone rubber, and the fluororesin is a baked layer of PTFE, PFA, FEP or a mixture thereof, in order to improve the releasability of the roller surface or to prevent offset. This is also a desirable configuration.

The rubber hardness of the first layer is not more than 20 degrees and not less than 0.1 degrees in JIS A hardness, and the thickness of the rubber layer is not more than 0.1 degree.
The thickness is preferably 1 mm or more and 10 mm or less from the viewpoints of image quality, prevention of wrinkles on the roller surface, and fixability.

[0022]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples.

[0023]

Example 1 Roller surface with outer diameter of 40 mm, length of 240 m
JIS through a primer on the surface of a hollow aluminum core
Silicon rubber having an A hardness of 1 degree was formed into a thickness of 1.8 mm, and subjected to primary vulcanization at a temperature of 160 ° C for 30 minutes.
Then, silicon rubber having a JIS A hardness of 27 degrees was applied to the outer layer of the first silicon rubber layer of the same roller by 0.5 mm.
And then vulcanized at a temperature of 150 ° C. for 30 minutes. Thereafter, secondary vulcanization was performed at a temperature of 200 ° C. for 4 hours. After that, polytetrafluoroethylene (PTF
E) The dispersion was spray-coated to a thickness of 35 microns, and baked at a temperature equal to or higher than the firing temperature of the PTFE resin. Silicone rubber having a two-layer structure was coated on the outermost layer with the fired PTFE resin. An elastic rotating body having a layer structure was obtained. The two rollers were mounted on a fixing device of a full-color printer, and a printing process was performed with a fixing pressure of 40 kg. This roller has a durability of 100,000 or more in a printing process of four sheets per minute, and an image having no problem in fixability and gloss was obtained. In addition, it was proved that the fluororesin layer on the roller surface had no wrinkles and had excellent durability.

The hardness of the roller including the fluororesin-coated surface of this elastic rotating body was 54 degrees in Asker C hardness.
The evaluation results are summarized in Table 1 below.

[0025]

Comparative Example 1 Using the same core as in Example 1, J
Silicon rubber having an ISA hardness of 30 degrees was molded to a thickness of 2 mm, and subjected to primary vulcanization and secondary vulcanization under the same conditions as in Example 1. Thereafter, the surface of the silicone rubber was coated with a PTFE dispersion to a thickness of 35 μm, and baked under the same conditions to obtain an elastic rotating body having a two-layer structure of a silicone rubber elastic layer and a fluororesin layer.

The elastic rotator was mounted on the fixing machine of Example 1 and subjected to a copying test under a fixing pressure of 50 kg. As a result, no wrinkles were generated in the fluorine resin layer, but the nip width was narrow and the fixing property was obtained. I couldn't. The evaluation results are summarized in Table 1 below.

[0027]

Comparative Example 2 A two-layer structure of a silicon rubber elastic body and a fluororesin layer was prepared under the same conditions as in Comparative Example 1 except that the hardness of the silicone rubber elastic layer was changed to JIS A25 degrees and the thickness was changed to 5 mm. An elastic rotator was obtained.

At a fixing pressure of 50 kg, the nip width of this elastic rotator was slightly wider than that of Comparative Example 1, and the fixing property was slightly improved. However, wrinkles and breakage occurred slightly on the surface of the fluororesin layer. The evaluation results are summarized in Table 1 below.

[0029]

Comparative Example 3 Using the same core as in Example 1, only one layer of the silicone rubber having a JIS A hardness of 1 used in the first layer of Example 1 was formed on the surface of the core with a thickness of 2 mm. After vulcanizing under the same conditions as in Example 1, coating with a PTFE resin dispersion, followed by baking to produce a roller having one silicon rubber layer and the surface of which was covered with PTFE resin.

The same two rollers were mounted on the fixing device of the printer of Example 1, and the printing process was performed at a fixing pressure of 40 kg and 30 kg, respectively. As a result, the fixing property of the toner was good. The resin layer was stretched, wrinkled, and the film was broken. The evaluation results are summarized in Table 1 below.

[0031]

Embodiment 2 Using the same core body as in Embodiment 1, the elastic layer has a silicone rubber hardness of JIS A 0.5 degree and a thickness of 1.9 mm.
Then, an elastic body in which the silicone rubber of the buffer layer has a hardness of JIS A35 degrees and a thickness of 0.25 mm is formed, vulcanized under the same conditions as in Example 1, and an elastic rotating body coated with a fluororesin is obtained. .

In the fixing test of Example 1, the elastic rotator obtained no problem in fixing property, shininess and durability. The evaluation results are summarized in Table 1 below.

[0033]

Comparative Example 4 An elastic rotating body was manufactured in the same manner as in Comparative Example 3 except that the elastic layer was changed to 1.0 mm. The obtained elastic rotating body has a high degree of elongation and wrinkling of the fluororesin layer, which may cause breakage. In addition, since the thickness of the first elastic layer is small, a sufficient nip width cannot be obtained, and the fixing property is poor. Could not be used as. The evaluation results are summarized in Table 1 below.

[0034]

Comparative Example 5 Using the same core body as in Example 1, the first layer of JIS A hardness silicone rubber used in the first layer of Example 1 was molded as a first layer to a thickness of 0.5 mm under the same conditions. After vulcanization, a silicone rubber with a hardness of 27 degrees
A roller was formed as a layer and then vulcanized and coated with a fluororesin under the same conditions as in Example 1.

This roller was mounted on the fixing device of the same printer in Example 1 and printed. As a result, no wrinkles were generated in the fluororesin layer and no destruction of the film was observed, but a clear image having poor fixability was obtained. Did not. The evaluation results are summarized in Table 1 below.

[0036]

Example 3 A silicon rubber roller having a two-layer structure was manufactured under substantially the same configuration and under the same manufacturing conditions as in Example 1 except that the thickness of the buffer layer was 0.25 mm, and a 50 μm thick PFA tube was used as a fluororesin layer. Was obtained. The hardness of the roller including the fluororesin-coated surface of this elastic rotating body is 62 degrees in hardness of Asker C, so that almost good image quality and fixability can be obtained, and there is no wrinkle on the PFA tube surface and the durability is good. there were. The evaluation results are summarized in Table 1 below.

[0037]

Embodiments 4 to 8 In addition to the vulcanization treatment and the fluororesin treatment performed under the same core and the same conditions as in Embodiment 1, the hardness and thickness of the elastic body and the hardness of the buffer layer were measured in Embodiments 4 to 8, respectively.
To produce an elastic rotor.

The fixing performance of this elastic rotating body was evaluated in Example 1.
As a result of evaluation under the same conditions as above, good results were obtained in all of the fixing property, glossiness, wrinkle, elongation, breakage, etc. of the fluororesin layer.

[0039]

[Table 1]

[0040]

As described above, according to the present invention, in the elastic layer and the buffer layer coaxially arranged on the surface of the cylindrical core, the rubber of the first elastic layer in contact with the core is provided. The elastic rotating body having a hardness lower than the hardness of the second buffer layer, a thick elastic layer of the first layer, and a fluororesin layer on the outer layer was used as a heat fixing roller of a copying machine or a printer. In this case, it was possible to maintain a high quality image without sufficient fixability and shine, high reliability, and long durability. With such a configuration, the fixing performance is affected by the hardness, the rubber thickness and the fixing pressure of the silicon rubber, the hardness of the silicon rubber is low, the rubber thickness is large and the fixing pressure is high, that is, the contact area (nip area) between both rollers. The larger the value, the better the fixability.

However, wrinkles are generated on the surface coated with the fluororesin, however, the nip area required for fixing is secured by the first layer of the silicone rubber, and the deformation amount of the rubber is reduced by the second rubber layer. This has the effect of preventing the fluororesin layer from wrinkling.

At the same time, if the thickness of each rubber layer is too large, thermal conductivity is reduced, so that sufficient fixability may not be obtained. Therefore, the effects of the present invention can be expanded by selecting factors such as the thickness, hardness, and thermal conductivity of each rubber layer, the fixing pressure, and the thickness of the fluororesin under appropriate conditions.

Claims (7)

[Claims] 1. An elastic rotating body having an elastic layer on a surface of a core body and a fluororesin layer on an outer layer, wherein a buffer layer is provided between the elastic layer and the fluororesin layer to reduce a difference in expansion and contraction of each layer. An elastic rotating body, wherein the hardness of the buffer layer is higher than the hardness of the elastic layer. 2. The elastic body is silicone rubber, and the fluororesin is polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkylvinylether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer ( The elastic rotating body according to claim 1, wherein the elastic rotating body is at least one calcined layer selected from PFEP) and a tetrafluoroethylene-ethylene copolymer. 3. The elastic layer has a rubber hardness in the range of 0.1 to 20 degrees in JIS A hardness and a thickness of 0.1 to 20 degrees.
The elastic rotating body according to claim 1, wherein the elastic rotating body has a range of 1 mm or more and 10 mm or less. 4. The elastic rotating body according to claim 1, wherein the thickness of the elastic layer ≧ the buffer layer> the thickness of the fluororesin layer. 5. The elastic rotating body according to claim 1, wherein the buffer layer is an elastic body. 6. The elastic rotating body according to claim 1, wherein the buffer layer is at least one selected from silicone rubber, fluorine rubber, and a mixture thereof. 7. The elastic rotating body according to claim 1, wherein the thickness of the buffer layer is in a range of 0.1 mm or more and 3 mm or less.