JP2007334376A - Fixing member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing belt and a fixing roller that have satisfactory heat conductivity and electric conductivity and are black. <P>SOLUTION: A heat member has an elastic layer and heats a member to be heated by coming into contact with the member to be heated. The elastic layer is formed from a material composed of only carbons having heat conductivity and electric conductivity, and an elastic polymeric material. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fixing belt and a fixing roller which are used in an image forming apparatus such as a copying machine and which are built in a fixing device that fixes an unfixed toner image on a recording material.

  An image forming apparatus such as a copying machine includes a fixing device that fixes a toner image on a recording material by heating and pressurizing an unfixed toner image transferred onto the recording material such as paper. There are a fixing belt and a fixing roller which are incorporated in such a fixing device and directly contact a recording material to fix an unfixed toner image.

  A typical fixing belt has a structure in which a heat-resistant layer made of a heat-resistant resin (for example, polyimide), an elastic layer made of an elastic body (for example, silicone rubber), and a recording material and toner adhere to the fixing belt. It consists of three layers of a release layer made of (for example, a fluororesin). Such a fixing belt is heated by a heat roller that contacts and heats the heat-resistant layer, and simultaneously, an unfixed toner image on the recording material is heated by a pressure roller that contacts the heat-resistant layer and pressurizes the toner image on the recording material. And pressurizing to fix on the recording material.

  Note that the fixing belt is formed as thin as possible for the purpose of shortening the waiting time in heating and saving power, and has been devised to improve the thermal conductivity performance of the material itself used for each layer. Among them, as a device for improving the thermal conductivity performance of the material itself, a composite tubular article having a tubular inner layer made of polyimide resin containing boron nitride having high thermal conductivity performance and a tubular outer layer containing boron nitride in silicone rubber or fluoro rubber Has been proposed (see Patent Document 1).

On the other hand, the fixing roller has a heating element inside and is different from the fixing belt in that it directly heats itself and presses the toner image on the recording material, but each layer is used for the purpose of shortening the waiting time and heating power. The fixing belt is similar to the fixing belt in that the heat conductivity performance of the material itself is improved.
JP 2000-147928

  Incidentally, there is an “electrostatic offset phenomenon” as a problem in the fixing belt and the fixing roller. This is a phenomenon in which when the toner is fixed, the toner adheres and remains on the fixing belt, and the subsequent recording material is soiled. In order to prevent this, a system in which a bias voltage is applied so as to form an electric field in a direction in which the toner repels from the fixing belt and is pressed against the recording material side is often used. Specifically, an electrode member that connects the recording material to the ground is newly provided, a bias voltage is applied between the electrode member and the fixing belt, and a current that flows from the fixing belt to the ground through the recording material. By forming a path, the “electrostatic offset phenomenon” is prevented.

  In such a case, it is desirable in terms of the construction of the fixing belt that not only the outermost layer constituting the fixing belt but also the elastic layer inside thereof be electrically reduced in resistance. However, when boron nitride is used to improve the thermal conductivity performance as in the conventional example, the electrical resistance value of the boron nitride itself is high, so even if it is used for the fixing belt by kneading with silicone rubber or the like. As a result, the “electrostatic offset phenomenon” may not be prevented.

  In addition, the copying machine includes an optical device, and it is desirable that the parts used for optical processing and optical color correction are black so as not to reflect light, but boron nitride is white and adjacent to the optical device. Therefore, it is not preferable to use it for a fixing belt which has a possibility of failure.

The present invention has been made to solve the above problems, and its object is to
An object of the present invention is to provide a fixing belt and a fixing roller which have good heat conductivity and electric conductivity and are black.

In order to solve the above problems, the invention of claim 1 is a heating member that has an elastic layer and heats the member to be heated by contacting the member to be heated. The elastic layer has thermal conductivity and electrical conductivity. It consists of the material which consists only of carbon which has, and the polymeric material which has elasticity.
In the invention of claim 2, the material consisting only of carbon having thermal conductivity and electrical conductivity is obtained by dispersing, firing, and carbonizing carbon nanotubes in a polymer solution composed of components derived from natural materials. It is characterized by being.
The invention of claim 3 is characterized in that the polymer solution is a silk solution.
The invention of claim 4 is characterized in that the material composed only of carbon having thermal conductivity and electrical conductivity is black.
The invention of claim 5 is characterized in that the polymer material is silicone rubber.
The invention according to claim 6 is characterized in that the heating member has a belt shape or a roller shape.
According to a seventh aspect of the invention, the heating member is a part of a fixing device that fixes a toner image on a recording material, which is a heated member, onto the recording material.
The invention according to claim 8 is characterized in that the heating member is a fixing belt.
The invention according to claim 9 is characterized in that the heating member is a fixing roller.

  In the present invention, it is possible to provide a fixing belt and a fixing roller which have good thermal conductivity and electrical conductivity and are black.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is an explanatory diagram showing an example of the structure of the fixing belt 10.
Reference numeral 11 denotes a heat-resistant layer 11 made of a heat-resistant resin. An elastic layer 12 is formed on the outer peripheral surface of the heat-resistant layer 11, and a release layer 13 is further formed on the outer peripheral surface thereof to constitute the fixing belt 10. Here, although shown as a tubular shape, it may be used as an elliptical shape as well as a tubular shape when mounted on the fixing device.
A heat roller (not shown) is disposed inside the heat resistant layer 11 so as to be in pressure contact with the heat resistant layer 11. This heat roller is an aluminum hollow roller and has a heater inside. Although a halogen heater is used as the heater, it is not limited to this, and IH may be used. Further, a pressure roller A (not shown) is disposed inside the heat resistant layer 11 so as to be in pressure contact with the heat resistant layer 11 at a position where it does not contact the heat roller. This pressure roller has a silicone rubber layer on the outer surface of an iron cored bar.
Further, another pressure roller B is arranged at a position between the pressure roller A and the recording material. In general, in order to improve the peelability after fixing of the recording material, the pressure roller A inside the heat-resistant layer 11 is relatively softer than the pressure roller B. The pressure roller B always presses another pressure roller A using a spring material or the like, but the pressure roller B is not limited to this, and either pressure roller may be provided with a spring material or the like. In addition, the recording material is sandwiched between two pressure rollers this time, but the present invention is not limited to this. The recording material is attached to the tensioning portion of the fixing belt that is stretched between two supporting members. It is also possible to adopt a form in which the pressure roller is brought into pressure contact with the sheet interposed therebetween.

    The heat resistant layer 11 is made of a heat resistant resin. Examples of the heat-resistant resin include polyester, polyethylene, polyether, polyimide, polyamide and the like, and polyimide was selected this time. Moreover, you may add heat conductive fillers, such as carbon black, aluminum oxide, or a silicon oxide, to a heat resistant resin as needed. In that case, a calcined carbon powder of silk and carbon nanotubes (hereinafter abbreviated as CNT) as will be described later (this is a material consisting only of carbon having thermal conductivity and electrical conductivity in the claims, hereinafter referred to as CNT composite powder) Is good. Here, the carbon nanotubes are used as a concept including carbon nanofibers, carbon nanohorns, and the like.

    As a method for forming a belt, a liquid polyimide resin is applied onto an endless belt while adjusting the thickness uniformly with a doctor blade or the like, and dried and semi-cured with hot air or the like. At that time, it may be applied and dried so as to have a desired thickness divided into a plurality of times. After peeling off from the endless belt, adjusting the length in the width direction and the like, the belt-shaped polyimide resin heat-resistant layer 11 was formed by heating and curing in a heating furnace.

    The elastic layer 12 is made of a material having heat resistance and elasticity. Silicone rubber is good as such a material. The present invention is characterized in that a CNT composite powder as described later is blended with silicone rubber used as an elastic layer.

  As a method for producing the CNT composite powder, a silk solution is first produced by hydrolyzing a silk raw material. The silk solution can be formed by adding a silk raw material to a calcium chloride aqueous solution, heating and dissolving it, and further adding a proteolytic enzyme and hydrolyzing it. The silk material is a general term for woven fabrics, knitted fabrics, powders, cotton, yarns, and the like made of rabbits or wild silkworms. These can be used alone or in combination.

CNT is added to the silk solution. Although the addition amount is not particularly limited, it can be added in the range of 1 to 30 wt% with respect to the silk solution.
In order to disperse CNTs in the silk solution, it is preferable to apply ultrasonic waves to the silk solution.

A silk solution in which CNTs are dispersed is spread on a support film such as polypropylene and dried at room temperature or by heating. The dried mixed material is peeled off from the support film.
Alternatively, the silk solution may be spray-dried to form a granular mixed material.

The above mixed material is fired at a temperature of about 500 ° C. to 3000 ° C. in a non-oxidizing atmosphere, and then pulverized to form a CNT composite powder.
Firing and pulverization may be repeated a plurality of times to form a CNT composite powder having a required particle size.
The CNT composite powder has a structure in which CNTs are bound and mixed uniformly using a carbide of a silk material as a binder, and is a baked carbon powder excellent in thermal conductivity and electrical conductivity.

  This CNT composite powder is blended in a silicone rubber solution, spray-coated on the outer surface of the heat-resistant layer 11, and heat-cured in a heating furnace, whereby the elastic layer 12 which is a belt-like silicone rubber layer is formed on the outer surface of the heat-resistant layer 11. Formed.

    The release layer 13 is made of a fluororesin in order to improve toner releasability, transferability, and toner cleaning properties. Examples of the fluororesin include PTFE and PFA. I chose PTFE this time. Moreover, you may mix | blend a heat conductive filler and the above-mentioned CNT composite powder with a PTFE solution like the heat-resistant layer 11 as needed.

    As a method for forming the release layer 13, a PTFE solution is spray-coated on the outer surface of a plurality of layers including the heat-resistant layer 11 and the heat-insulating layer 12, and heat-cured in a heating furnace to thereby form the release layer 13 from the heat-resistant layer 11 and the heat-insulating layer 12. Formed on the outer surface of a plurality of layers.

The fixing belt 10 thus formed is excellent in thermal conductivity and electrical conductivity, and the “electrostatic offset phenomenon” does not occur even when the fixing belt 10 is mounted on the fixing device. In addition, the CNT composite powder is black because it is made of only carbon by being baked at a high temperature in the production process. Therefore, it was also good when used as a fixing belt that may be adjacent to optical equipment.
In addition, although CNT composite powder is only made of carbon, this means that most of the components are carbon, and actually nitrogen derived from silk is left. The amount of these residues varies mainly depending on the firing temperature. Moreover, it may act suitably with respect to thermal conductivity or electrical conductivity. In some cases, the firing temperature may be controlled to remain.

Example 1:
1) Preparation of silk solution First, a silk solution was prepared.
In a 65 wt% aqueous solution of calcium chloride hydrate, 240 g of silk raw material was added, and heating and dissolution were performed for 6 hours while maintaining the solution temperature at 95 ° C. Proteolytic enzyme was added and hydrolyzed by treatment at 60 ° C. for 24 hours.
Next, the dissolved solution after the decomposition is filtered to remove undissolved materials, and the silk solution obtained by desalting the filtrate using the dialysis membrane of the molecular fraction 300 is further concentrated to 35 wt%. Of silk solution.

2) Mixing and drying of silk solution and CNT The silk solution prepared in 1) and VGCF-H (registered trademark, manufactured by Showa Denko KK) were dispersed and dried by the following method.
Place 3085 g of silk solution in a stainless beaker. Thereafter, 100 g of VGCF-H is put into a resin lid, and is gradually added to the silk solution and dispersed with a glass rod. When 100 g is added, 100 g is weighed and dispersed again, and a total of 200 g is added. Thereafter, the mixture was dispersed with an ultrasonic cleaner for 5 minutes while stirring with a glass rod.
Next, about 20 g of the mixed solution was applied to the polypropylene sheet within a specified range (450 cm ² : 25 cm × 18 cm). Four polypropylene sheets were placed on one stainless steel shelf of the dryer, a total of 10 stainless steel shelves and a total of 40 polypropylene sheets were placed in the dryer and dried at 105 ° C. for about 1 hour. The polypropylene sheet was taken out from the dryer, bent about 10 seconds later to peel off the film from the polypropylene sheet, and the film (mixed material) adhering to the polypropylene sheet due to static electricity was collected with a stainless spatula. Membranes were collected from a total of 40 polypropylene sheets.

3) Primary firing The mixed material prepared in 2) was fired by the following method.
Each stainless steel tray was loaded with 600g of film and carried by a cart that put about 4kg of film into the required number of trays, and the trays were lined up in a ratio of two on one graphite plate in the basket of the primary firing furnace. It was fired by holding at 750 ° C. for 6 hours in a nitrogen atmosphere, and cooled to room temperature.

4) Grinding The mixed material fired in 3) was ground by the following method.
It grind | pulverized with the mortar until the mesh opening passed through the large sieve, and grind | pulverized for 1 day with the ball mill. Subsequently, each 200 g was classified with a sieve having an opening of 45 μm and collected in a resin container. The powder that did not pass was ground again with a ball mill for 24 hours, and the classification process was repeated with a sieve.

5) Secondary firing The mixed material powder pulverized in 4) was fired by the following method.
Firing was carried out while maintaining an argon atmosphere at 2400 ° C. for 3 hours, and cooled to room temperature.

6) Classification The mixed material powder fired in 5) was classified with a sieve having an opening of 32 μm.

7) Mixing with silicone rubber solution 50 wt% of the mixed material powder (CNT composite powder) classified in 6) was mixed with the silicone rubber solution.

  Here, in order to measure various characteristics of the silicone rubber containing the CNT composite powder, it was heated at 170 ° C. for 5 minutes in a heating furnace and further heated at 200 ° C. for about 2 hours. It was formed into a 3 cm × 3 cm × 5 mm sheet.

Comparative Example 1:
Further, when the CNT composite powder was not blended, that is, various characteristics only of silicone rubber were similarly formed in a sheet shape as a comparative example.

The measurement results of Example 1 and Comparative Example 1 are shown in Table 1.

  From the measurement results in Table 1, it can be seen that both thermal conductivity and electrical conductivity are excellent. As a result, when the fixing belt or the fixing roller is used as the elastic layer, it can be seen that the time to reach the toner fixing temperature is greatly shortened and effective against the “electrostatic offset phenomenon”.

Example 2:
A fixing belt was formed by the following method.
1) Formation of heat-resistant layer A polyimide solution was applied onto an endless belt rotating at a constant speed while uniformly adjusting the thickness with a doctor blade. At this time, the endless belt is made of silicone rubber in consideration of peeling off the semi-cured polyimide resin in a later step. Thereafter, it is dried and semi-cured by blowing hot air of about 100 ° C. After that, it was peeled off from the endless belt and cut to adjust the length in the width direction. It was heat-cured at approximately 380 ° C. for 40 minutes in a heating furnace.
Thus, a heat-resistant layer made of polyimide resin having a thickness of about 50 μm was formed.

2) Formation of elastic layer The silicone rubber solution containing the CNT composite powder prepared in Example 1 was spray-coated on the outer surface of the heat-resistant layer. It was heated at 170 ° C. for 5 minutes and further heated at 200 ° C. for about 2 hours.
In this manner, an elastic layer made of silicone rubber containing CNT composite powder having a thickness of about 150 μm was formed.

3) Formation of release layer A PTFE solution was spray-coated on the outer surfaces of a plurality of layers composed of the heat-resistant layer and the heat-insulating layer described above. It was heat-cured in a heating furnace at 170 ° C. for 15 minutes.
In this way, a release layer having a thickness of about 20 μm was formed.

  The fixing belt thus formed was mounted on a test copying machine, and a toner fixing test was performed. However, the “electrostatic offset phenomenon” did not occur. Moreover, since it was black, it was favorable even when the optical apparatus was adjacent.

Structure diagram of fixing belt

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Fixing belt 11 Heat resistant layer 12 Elastic layer 13 Release layer

Claims (9)

In a heating member that has an elastic layer and heats the heated member by contacting the heated member,
The heating member, wherein the elastic layer is made of a material composed only of carbon having thermal conductivity and electrical conductivity, and a polymer material having elasticity.   The material comprising only carbon having thermal conductivity and electrical conductivity is obtained by dispersing, firing, and carbonizing carbon nanotubes in a polymer solution composed of components derived from natural materials. Item 2. A heating member according to Item 1.   The heating member according to claim 1, wherein the polymer solution is a silk solution.   The heating member according to any one of claims 1 to 3, wherein the material made of only carbon having thermal conductivity and electrical conductivity is black.   The heating member according to claim 1, wherein the polymer material is silicone rubber.   The heating member according to claim 1, wherein the heating member has a belt shape or a roller shape.   The heating member according to claim 1, wherein the heating member is a part of a fixing device that fixes a toner image on a recording material, which is a heated member, onto the recording material.   The heating member according to claim 1, wherein the heating member is a fixing belt.   The heating member according to claim 1, wherein the heating member is a fixing roller.

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