JP2002195248A - Pressure roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure roller used for a fixing device capable of forming high quality of pictures having no errors such a smearing and the like and also having superior durability, in the pressure roller applied to the fixing device that uses a heating roller and a pressure roller in the fixing device of an electronic coping machine. SOLUTION: In the pressure roller coated with a fluorocarbon resin sleeve of less than 1.5 mm thickness in an outer periphery of an elastic body layer coated in an outer periphery of core metal, the elastic body layer is made of silicone rubber having 31 to 55 degrees of hardness (Type A Duro Meter specified in JIS K 6253). Further, silicone rubber having 55 to 78% of rebounding elasticity (Luepke type rebounding elasticity in JIS K 6255) is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a pressure roller applied to a fixing device using a heating roller and a pressure roller in a fixing device of an electronic copying machine.

[0002]

2. Description of the Related Art Conventionally, as a pressure roller in a fixing device of an electronic copying machine, a roller in which a rubber roller containing a core is covered with a fluororesin sleeve in order to improve toner releasability has been known. As shown in Japanese Patent Publication No. Sho 50-7097 or Japanese Patent Publication No. Sho 51-27276, for example, this type of conventional roller has an inner diameter of a cylindrical mold loaded inside an inner peripheral surface of the cylindrical mold. Both ends of the fluororesin sleeve having a smaller outer diameter are fixed to the side mold that holds the core, and in this state, a rubber material is injected and filled into the annular space between the core and the sleeve at a high pressure, and the sleeve is filled with the filling pressure. It is manufactured by a method in which the sleeve is made to adhere to the inner peripheral surface of the cylindrical mold while expanding the sleeve, and the sleeve is integrated with the rubber material.

[0003]

In a fixing device using a conventional pressure roller manufactured by such a method, image bleeding (dirt) often called image smear sometimes occurs. . This is caused by some speed mismatch when a toner image is transferred from a photoconductor to a sheet by a transfer device in a copying machine. For this purpose, Japanese Patent Application Laid-Open No. Hei 8-227189 discloses that a test pattern is printed on a plurality of sheets in order to optimize a sheet conveying speed, and a sheet transfer speed is changed for each of the plurality of sheets. It discloses a method of optimizing the transfer speed that minimizes image smear provided with, but such a method results in an increase in the size of the device itself,
Further, there is a disadvantage that the cost is increased. When the space of the paper conveyance path from the photosensitive member (drum) to the fixing device is shortened to reduce the size of the image forming apparatus, particularly when the leading edge of the paper enters the fixing device, the speed on the toner image is reduced. Fluctuations occur and cause image smear. Therefore, if the impact at the time of entering the paper is alleviated, image smear will not occur, and the present inventors have focused on the elastic body of the pressure roller used in the fixing device as one of the means, and determined the rebound resilience. It has been found that if the amount is reduced, the impact when the leading edge of the sheet enters the fixing device can be reduced, and the occurrence of image smear can be suppressed.

However, in order to extend the life of the roller, the elastic rubber layer is usually made of silicone rubber having a compression set of 10% (test method: JIS K 6262, test condition: 180 ° C. ×
22 hours) The rebound resilience (JIS K 6255) is very high, around 80-85%, because of the use of a low set material of less than
In other words, it was a trade-off relationship. The present invention has been made in view of these points, and provides a pressure roller used in a fixing device, which can form a high-quality image without image defects such as smear and has extremely excellent durability. The purpose is to do.

[0005]

In order to achieve the above object, the present invention provides a pressurizing method in which a fluororesin sleeve having a thickness of 0.15 mm or less is coated on the outer periphery of an elastic layer coated on the outer periphery of a metal core. In the roller, the elastic layer has a hardness of 31 to 31.
A pressure roller characterized in that it is 55 degrees (JIS K 6253 type A durometer) silicone rubber and has a rebound resilience (Lupke rebound resilience of JIS K 6255) of 55 to 78%. In particular, in the present invention, it is preferable that the vibration damping material is mixed with the silicone rubber of the elastic layer coated on the outer periphery of the cored bar. Furthermore, the present inventors have conducted intensive research and as a result, have found that, by using English mica as a vibration damping material, a pressure roller capable of suppressing the occurrence of image defects such as smears is manufactured, and completed the present invention. Was.

Here, since some types of damping materials cause deterioration of the compression set, it is desirable that the compression set is 10% or less under the above conditions. It is necessary to consider. According to the present invention, as the elastic layer covering the outer periphery of the core metal of the pressure roller used in the fixing device, by using silicone rubber in which a vibration damping material is mixed with silicone rubber, smear or the like can be obtained. It is possible to provide a roller that does not cause image defects and has a long-term durability as a pressure roller.

[0007]

FIG. 1 is a block diagram showing an embodiment of the present invention.
Will be described. FIG. 1 shows an embodiment of the present invention, which is applied to a pressure roller used in a fixing device of a copying machine. The pressure roller 1 has an elastic layer 3 made of silicone rubber coated on the outer periphery of a metal core 2.
Further, the outer periphery of the elastic layer 3 is covered with a fluororesin sleeve 4 made of PFA (tetrafluoroethylene-perfluoroalkylvinyl ether copolymer).

The elastic layer 3 is formed of an addition-type silicone rubber comprising a vinyl-containing polyorganosiloxane and a hydrogen-polysiloxane or a peroxide-cured vulcanizate comprising a vinyl-containing polyorganosiloxane and an organic peroxide. A silicone rubber composition containing a vibration damping material in silicone rubber has been used. As the vibration damping material in the present invention, mica powder such as English mica, talc,
Examples thereof include aluminum powder, zinc carbonate, magnesium carbonate, magnesium dioxide, molybdenum disulfide, dex clay, and graphite, but English mica is good as a measure against image smear. KMG MINERALS (US, formerly known as THE ENGLISH MICA)
WetGround Mica (trade name) of the company. Since such vibration damping materials are often in the form of flakes, the inclusion of such a component in a rubber elastic material results in a material having low rebound resilience. Can be reduced. Therefore, it is considered that an image smear caused by an impact generated when the leading edge of the sheet enters the fixing device can be avoided.

Various additives such as fillers, fillers, colorants, conductive substances, heat-resistant agents, pigments, etc. are added to the elastic layer 3 according to the present invention in accordance with the purpose of use and design of the pressure roller. Agents can be added. For example, the formulation of the filler with respect to the elastic layer 3 is not particularly limited,
Usually, about 10 to 300 parts by weight of a reinforcing filler and an extending filler are added to 100 parts by weight of the base gum. As the reinforcing filler, carbon black and wet silica or dry silica (fumed silica) are generally used.
Here, the wet silica means silicon dioxide (SiO ₂ )
It is a reinforcing silica consisting of, as a production method, a direct method of directly decomposing sodium silicate with sulfuric acid, or reacting sodium silicate with salts to generate silicate, then sulfuric acid or carbon dioxide gas There are various methods such as an indirect method of decomposition. A typical wet silica is Nipsil VN3.
(Trade name, manufactured by Nippon Silica Industry Co., Ltd.), Carplex CS-5 (trade name, manufactured by Shionogi Pharmaceutical Co., Ltd.), Star Sill S (trade name, manufactured by Kamijima Chemical Industry Co., Ltd.), Toksil U
S (trade name of Tokuyama Corporation), Shilton R-2 (trade name of Mizusawa Chemical Industry Co., Ltd.), Hisil223 (trade name of PPG (USA)), Ultrasil VN3 (trade name of Deguzza (Germany)), Vulkasil S (trade name, manufactured by Bayer AG, Germany) and the like, and the average particle size is 30 μm.
Below, preferably, a grade of 5 μm or less is used.
Dry silica is a reinforcing silica made of silicon dioxide produced by the thermal decomposition method of silicon halide or the heat reduction of silica sand, and the air oxidation method of vaporized SiO and the thermal decomposition method of organic silicon compounds. , Aerosil 200 and Aerosil R
972 (trade name, manufactured by Nippon Aerosil Co., Ltd.), Cab-O
-Sil MS-5 (trade name, manufactured by Cabot Corporation (USA)),
Leoro Seal QS102 (trade name, manufactured by Tokuyama Corporation)
Is exemplified. In the present invention, wet silica and dry silica may be used in combination as needed. Further, a lubricant (wetter) may be added for the purpose of preventing secondary bonds due to the activity of the silica surface. Examples of the lubricant include silicone resins, alkoxysilanes and siloxanes, hydroxysilanes and siloxanes, and silazanes. , Organic acid esters, polyhydric alcohols and the like.

[0010] The bulking filler is a component necessary for maintaining the mechanical properties of rubber, that is, properties that are indispensable to function as the elastic layer 3 such as physical strength, rubber hardness and compression set. , Quartz powder, diatomaceous earth, zirconium silicate, clay (aluminum silicate), wollastonite (calcium metasilicate), titanium oxide, zinc oxide, magnesium oxide, alumina (aluminum oxide), chromium oxide, red iron oxide (oxidation) iron),
Examples thereof include aluminum sulfate, barium sulfate, and lithopone. Further, in order to impart conductivity to the elastic layer 3, various conductivity-imparting agents may be used as a filler to reduce the volume resistivity to 10 ¹³ Ω · cm or less. Examples thereof include conductive carbon black such as acetylene black and Ketjen black, metal powders such as silver, copper, and nickel, conductive zinc white, conductive calcium carbonate, and carbon fibers. Carbon black is generally used. Further, a heat resistant agent such as cerium oxide may be added to the silicone rubber.

Usually, a pressure roller made of silicone rubber is often supplied in a colored state of red, and in this case, it is common to use red as a coloring agent. As the type of bengara, a bengara for rubber specified in SRIS1108 (Japanese Rubber Association Standard) can be applied, and when it is necessary to pay attention to the orientation in the rubber during processing, Bayferox 130M (Bayer Corporation) (Germany brand name) and a spherical grade having an average particle size of 0.3 μm or less,
What is necessary is just to add about 2 weight%. If necessary, a conductivity-imparting agent such as conductive carbon black is added to the fluororesin sleeve 4 used for the surface layer of the present invention to form a conductive fluororesin having a volume resistivity of 10 ¹³ Ω · cm or less. Rollers may be formed.

In the present invention, the fluororesin sleeve 4 and the silicone rubber are adhered to each other by applying a silicone-based material such as Chemlock 607 (trade name of Road Far East, Inc.) to the inner surface of the fluororesin sleeve 4 which has been subjected to the inner surface treatment. By applying a primer and vulcanizing with the elastic layer 3 made of silicone rubber, it can be more firmly adhered to the elastic layer 3 and used, but it is not always necessary to use a primer. At this time, as a method for treating the inner surface of a fluororesin sleeve such as PFA, as disclosed in JP-A-2-191641,
Chemical treatment with a solution of sodium metal and naphthalene dissolved in F (tetrahydrofuran) or ethylene glycol dimethyl ether, Japanese Patent Publication No. 7-68381
, A method of chemical treatment with a solution of metallic sodium dissolved in liquid ammonia, a method of chemical treatment with mercury amalgam of an alkali metal such as lithium, an electrolytic reduction method, JP-A-2000-178369. A discharge treatment method as disclosed in
Atmospheric pressure glow discharge method of treating with an inert gas plasma such as helium or argon as disclosed in Japanese Patent Application Laid-Open No. 5365 and Japanese Patent Application Laid-Open No. 10-273546.
An example is a method of processing with an excimer laser as disclosed in Japanese Patent No. 38687.

The adhesion between the core metal 2 and the elastic layer 3 is performed by using a primer or primer for peroxide-cured silicone rubber such as Primer DY39-012 (trade name of Dow Corning Silicone Co., Ltd.). No. 101A / B
Stronger adhesion can be obtained by using a primer for addition-type silicone rubber such as (trade name of Shin-Etsu Chemical Co., Ltd.). At this time, the surface of the metal core 2 is previously activated by sandblasting or the like. Then, after degreasing with methylene chloride, hydrocarbon, or the like, a primer is applied, and if necessary, baked at 130 ° C. for about 30 minutes before use. It is important that the mold used in the present invention is inertized by hard chrome plating or the like, and is used together with a mold release agent such as Mold Spat MR-K681 (trade name, manufactured by Asahi Glass Co., Ltd.). Is done.

[0014]

The present invention will be described below more specifically with reference to examples. It should be noted that the present invention is not limited to the described embodiments, but can be implemented with some modifications as necessary.

As the pressure roller in the evaluation test, a roller having an outer diameter of 50 mm, a thickness of an elastic layer made of silicone rubber of 0.5 mm, a thickness of a fluororesin sleeve of 50 μm, and a length of the elastic layer of 320 mm was used. . After kneading the silicone rubber having the composition shown in Table 1 with an 8-inch roll, a roller is manufactured according to the manufacturing method disclosed in Japanese Patent Publication No. 50-7097, and the elastic layer 3 is formed. A roller was formed. Table 1 shows the silicone rubber composition of the elastic layer 3 used in the test.

[0016]

[Table 1]

The physical properties of the silicone rubber having the composition shown in Table 1 were measured according to JIK K 6251, 6253, 6255. Table 2 shows the physical properties of each sample described in Table 1.

[0018]

[Table 2]

Next, Table 3 shows the results of a paper passing test by a copying machine for each of the above samples. In the paper passing test using a copier, Vivace 555 (product name) manufactured by Fuji Xerox Co., Ltd. was used as the copier, and 100 sheets of A4 size PPC paper were passed.
Evaluation was made based on the occurrence rate of image smear.

[0020]

[Table 3]

From the results of Tables 1 to 3, Comparative Examples 1 and 2
With high rebound resilience silicone rubber to which no vibration damping material is added, image smear occurs with a probability of several percent,
It was found that image smear did not occur in the pressure rollers of Examples 1 to 4 using the silicone rubber containing the vibration damping material and having low rebound resilience. Further, a pass-through test of 350,000 sheets was performed on the rollers of each of the examples prepared in this manner. Even after the test was completed, in the test using the rollers of Examples 1 to 4, image smear was generated. Did not.

[0022]

As described above, since the pressure roller according to the present invention is constructed and functions, the use of the addition type silicone rubber containing the adhesion imparting agent makes it possible to peel off the adhesion between the core metal and the fluororesin sleeve. In addition, there is an effect that the durability becomes extremely excellent.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a pressure roller of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Roller 2 Core metal 3 Silicone rubber elastic layer 4 Fluororesin sleeve

Claims (3)

[Claims] 1. A pressure roller in which a fluororesin sleeve having a thickness of 0.15 mm or less is coated on an outer periphery of an elastic layer coated on an outer periphery of a cored bar, wherein the elastic layer has a hardness of 31 to 31 mm.
A pressure roller made of silicone rubber of 55 degrees (JIS A 6253 type A durometer) and having a rebound resilience (Lupke rebound resilience of JIS K 6255) of 55 to 78%. 2. The pressure roller according to claim 1, wherein the silicone rubber contains a damping material. 3. The pressure roller according to claim 1, wherein the vibration damping material is English mica.