JP2010097087A - Fixing member, method for producing fixing member, fixing device and image forming apparatus equipped with same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing member excellent in durability and flexibility, a fixing device with the fixing member incorporated therein, and an image forming apparatus capable of forming a glossy image by being equipped with the fixing device. <P>SOLUTION: The fixing member includes a core material and a release layer formed on a surface of the core material. The release layer is formed by curing a coating material prepared by mixing a crosslinked fluorocarbon resin and an uncrosslinked fluorocarbon resin in a ratio of 30:70 to 70:30. The uncrosslinked fluorocarbon resin has a melting point of 250-300°C and a melt flow index of 5-25 g/10 min. An image is formed with an image forming apparatus equipped with a fixing device obtained by incorporating such a fixing member. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is mounted on an electrophotographic image forming apparatus used for a copying machine, a laser printer, a facsimile, and the like, and is incorporated into a fixing device for fixing a toner image on a recording medium, a fixing device, and an image forming apparatus including the fixing member. The present invention relates to an apparatus and a method for manufacturing the fixing member.

  An electrophotographic image forming apparatus, which is often used in copying machines, laser printers, facsimiles, and the like, applies a charge to the surface of a latent image carrier to uniformly charge the image, and then performs various image forming processes. An electrostatic latent image corresponding to the information is formed. The electrostatic latent image is converted into a toner image using a developer supplied from a developing unit, and the toner image is directly transferred to a recording medium such as paper. Alternatively, the image is once transferred to an intermediate transfer medium and then transferred to a recording medium. The toner image transferred to the recording medium is then fixed on the recording medium by a fixing device.

  As a fixing method of the toner image, a heat fixing method is generally used, and for example, a heat roller fixing method is exemplified.

  In the heat roller fixing method, a pair of rollers comprising a heat roller having a heat heater inside and having an outer periphery coated with rubber or resin having good releasability and a rubber roller are pressed against each other, and a toner image is formed between the rollers. The toner is heated and melted by passing through the recording medium, and the toner image is fused to the recording medium.

  Further, there is a belt fixing method in which toner on the surface of a recording medium is heated by a heater through a cylindrical fixing belt. In a belt fixing method using a cylindrical fixing belt, the fixing belt and a rubber roller are pressed against each other, a recording medium on which a toner image is formed is passed between them, and the toner image is fused to the recording medium by the heat of the fixing belt. To fix. In this belt fixing method, since the heat capacity is low and the thin cylindrical fixing belt is heated, the surface of the fixing belt reaches a predetermined temperature in a short time, and the waiting time after power-on can be greatly reduced.

  Fixing members such as the heat roller and the fixing belt as described above are manufactured using, for example, a fluororesin tube as a surface layer. Specifically, the roller used in the heat roller fixing method is such that the inner surface of the roller mold is covered with a fluororesin tube, the core metal is placed in the mold, and then silicone rubber is placed between the tube and the core metal. It is obtained by an integral molding method in which the heat roller is molded by pouring and removing the roller mold. By using the fluororesin tube as the surface layer, it is possible to ensure the durability of the fixing member and the toner releasability as the speed increases.

  However, the thickness of the fluororesin tube cannot be reduced because of poor handling during manufacture. Further, since the resin is a resin, the surface layer of the fixing member becomes hard, and it is difficult to sufficiently melt and fix the toner following the unevenness of the recording medium, and it is impossible to provide a glossy high-quality image. Furthermore, since it is necessary to shape | mold in the shape of a tube, there also exists a problem that cost starts.

  Therefore, as an alternative to the fluororesin tube, a fixing member whose surface layer is coated with a fluororesin has been proposed. For example, in a roll in which a fluororesin coating layer is provided directly on the shaft core or through another coating layer, the fluororesin coating layer is made of uncrosslinked fluororesin on the inner peripheral surface side and cross-linked fluorine on the outer peripheral surface side. A roll made of a resin is disclosed in Patent Document 1. When the roll disclosed in Patent Document 1 is used as a fixing roll of a copying machine, excellent wear resistance and long life can be exhibited.

  Patent Document 2 discloses a fixing member comprising a fluororesin that is crosslinked by irradiating with ionizing radiation in a state where at least the surface layer is heated in an oxygen-free atmosphere and at a temperature equal to or higher than the crystal melting point. Has been. The fixing member disclosed in Patent Document 2 is excellent in both durability and high image quality aptitude.

  Patent Document 3 discloses a fixing member in which a surface layer is made of a fluoroelastomer containing a nonionic fluorosurfactant having at least a hydrophilic group of polyethylene glycol type, and the fluoroelastomer is a cross-linked fluoropolymer. Has been. The fixing member disclosed in Patent Document 3 can improve the toner release properties of the surface layer of the fluoroelastomer, has flexibility, and has good toner release properties and durability.

JP 2003-36002 A JP 2002-23539 A JP 2005-215153 A

  However, since the fixing members disclosed in Patent Documents 1 to 3 are fixing members whose surfaces are coated with a crosslinked fluororesin, they have the following problems. Among the fluororesins, when the cross-linked fluororesin comes to the surface, the durability as a fixing member can be maintained, but since the surface layer has a high elastic modulus and lacks flexibility, the toner image transferred onto the uneven recording medium surface It is difficult to melt the toner and sufficiently penetrate and fix it on the recording medium, and it is impossible to form a glossy image.

  An object of the present invention is to provide a fixing member excellent in durability and flexibility, a fixing device incorporating the fixing member, an image forming apparatus capable of forming a glossy image by including the fixing device, and the fixing member. It is to provide a manufacturing method.

The present invention is a fixing member comprising a core material and a release layer formed on the surface of the core material,
The release layer is formed by curing a coating material in which a crosslinked fluororesin and an uncrosslinked fluororesin are mixed at a ratio of 30:70 to 70:30,
The uncrosslinked fluororesin is a fixing member having a melting point of 250 ° C. or more and 300 ° C. or less and a melt flow index of 5 g / 10 min or more and 25 g / 10 min or less.

Further, the present invention is characterized in that the release layer has a thickness of 5 μm or more and 30 μm or less.
The present invention is also characterized in that the release layer has a surface roughness Ra of 0.3 μm or less.

According to another aspect of the present invention, there is provided a fixing device including the fixing member described above.
The present invention also provides an image carrier on which a latent image is formed,
A latent image forming means for forming a latent image on the image carrier;
An image forming apparatus comprising the fixing device.

Further, the present invention is a method for producing a fixing member comprising a core material and a release layer formed on the surface of the core material,
A coating material prepared by mixing a crosslinked fluororesin and an uncrosslinked fluororesin in a ratio of 30:70 to 70:30 is cured to form a release layer,
An uncrosslinked fluororesin having a melting point of 250 ° C. or more and 300 ° C. or less and a melt flow index of 5 g / 10 min or more and 25 g / 10 min or less is used.

  According to the present invention, there is provided a fixing member including a core material and a release layer formed on the surface of the core material, wherein the release layer includes a crosslinked fluororesin and an uncrosslinked fluororesin 30: The coating material mixed at a ratio of 70 to 70:30 is cured, and the uncrosslinked fluororesin has a melting point of 250 ° C. or more and 300 ° C. or less and a melt flow index of 5 g / 10 min or more and 25 g / 10 min or less. .

  Since the high temperature offset region of the toner is in the range of 230 ° C. or more and 250 ° C. or less, if the melting point of the uncrosslinked fluororesin is less than 250 ° C., the release layer of the fixing member also melts simultaneously with the heating of the toner during fixing. . The higher the melting point of the resin used in the release layer, the higher the modulus of elasticity of the release layer. Therefore, when the melting point of the uncrosslinked fluororesin exceeds 300 ° C., the flexibility of the fixing member as the surface material is inferior. When the toner melts at this time, it becomes difficult for the toner to follow the unevenness of the recording medium and to be fixed, and the fixability is lowered.

  If the melt flow index of the uncrosslinked fluororesin is less than 5 g / 10 min, which is the same as that of conventional fluororesin tubes, the surface layer material is inferior in flexibility, and the toner follows the unevenness of the paper when the toner melts during fixing. It becomes difficult to fix. When the melt flow index of the uncrosslinked fluororesin exceeds 25 g / 10 min, the aging resistance of the release layer is deteriorated and the durability of the fixing member is deteriorated.

  In the mixing ratio of the crosslinked fluororesin (hereinafter also referred to as “crosslinked fluororesin”) and the uncrosslinked fluororesin, when the crosslinked fluororesin is less than the specified value and the uncrosslinked fluororesin is mixed more than the specified value, The durability of the fixing member is poor. If the amount of cross-linked fluororesin is greater than the specified value and the amount of uncrosslinked fluororesin is less than the specified value, the elastic modulus of the release layer is undesirably increased. However, it becomes difficult to follow the unevenness of the recording medium.

  By mixing the crosslinked fluororesin and the uncrosslinked fluororesin having the melt flow index and melting point as described above at a ratio of 30:70 to 70:30, the crosslinked fluororesin and the uncrosslinked fluororesin are in an appropriate ratio. The release layer can be sufficiently mixed, and the elastic modulus can be lowered while maintaining the durability of the fixing member as compared with the case where the resin contained in the coating material is only a crosslinked fluororesin. Therefore, the fixing member can be a fixing member that is flexible enough to sufficiently fix the toner to the recording medium and excellent in durability.

  According to the invention, the thickness of the release layer is 5 μm or more and 30 μm or less. When the thickness of the release layer is less than 5 μm, the deterioration of the release layer is likely to proceed when cracks, scratches, and wear occur during fixing. When the thickness of the release layer exceeds 30 μm, the flexibility of the release layer is inferior, and when the toner is melted, it becomes difficult for the toner to follow the unevenness of the recording medium and be fixed. When the thickness of the release layer is 5 μm or more and 30 μm or less, it is possible to follow the minute irregularities of the recording medium while making use of the elasticity of the elastic layer, and to obtain a fixing member having further excellent flexibility and durability. be able to.

  According to the invention, the surface roughness Ra of the release layer is 0.3 μm or less. When the surface roughness Ra exceeds 0.3 μm, irregularities on the surface of the release layer appear in the toner image after fixing. When the surface roughness Ra of the release layer is 0.3 μm or less, a fixing member having excellent smoothness can be obtained.

  According to the invention, the fixing device includes the fixing member of the invention. As described above, the fixing member of the present invention can moderately reduce the elastic modulus while maintaining durability, and is excellent in durability and flexibility, so that the toner is smoothly melted and released during fixing. And a glossy image can be stably formed.

  According to the invention, the image forming apparatus includes the fixing device of the invention. As a result, the flexibility of the release layer can be increased to such an extent that the toner can be sufficiently fixed on the recording medium. Even when a toner image is formed by laminating toners as in a color image, the recording medium is melted when the toner is melted. Since the toner image can be fixed following the unevenness, an image having a glossy feeling can be formed.

  Further, according to the present invention, a fixing member manufacturing method including a core material and a release layer formed on the surface of the core material includes a crosslinked fluororesin and an uncrosslinked fluororesin 30:70 to 70. : A coating layer mixed at a ratio of 30 is cured to form a release layer, and an uncrosslinked fluororesin having a melting point of 250 ° C. to 300 ° C. and a melt flow index of 5 g / 10 min to 25 g / 10 min. Use. As a result, a release layer in which the crosslinked fluororesin and the uncrosslinked fluororesin are sufficiently mixed at an appropriate ratio can be formed, and the release layer can be formed using only the crosslinked fluororesin as the resin contained in the coating material. Compared to the manufacturing method, the elastic modulus can be lowered while maintaining the durability of the fixing member. Therefore, the fixing member is sufficiently flexible and excellent in durability so that the toner can be sufficiently fixed on the recording medium. Obtainable.

1. Fixing Member The fixing member according to the first embodiment of the present invention includes a core material and a release layer formed on the surface of the core material. The release layer is formed by curing a coating material obtained by mixing a crosslinked fluororesin and an uncrosslinked fluororesin in a ratio of 30:70 to 70:30. The uncrosslinked fluororesin has a melting point of 250 ° C. or more and 300 ° C. or less and a melt flow index of 5 g / 10 min or more and 25 g / 10 min or less.

(1) Embodiment 1A (Configuration of Fixing Device 6A)
FIG. 1 is a cross-sectional view schematically showing a configuration of a fixing belt 100A and a fixing device 6 incorporating the fixing belt 100A according to the first embodiment of the present invention. As shown in FIG. 1, the fixing device 6 </ b> A includes a fixing belt 100 </ b> A, a fixing roller 50, a heating roller 72, and a pressure roller 60.

  The fixing belt 100 </ b> A is an endless belt-like member that is stretched between the fixing roller 50 and the heating roller 72 to form a loop-shaped movement path. The fixing belt 100 </ b> A is provided so as to come into contact with the pressure roller 60 at a fixing nip portion 55 which is a pressure contact between the fixing roller 50 and the pressure roller 60, and constitutes a toner image carried on the recording medium 8. The toner is heated and melted and fixed on the recording medium 8. The fixing belt 100A is driven to rotate in the direction of the arrow 78A by the rotational driving of the pressure roller 60 in the direction of the arrow 56.

  The fixing roller 50 is a roller-like member that is rotatably supported by a support unit (not shown) and is driven to rotate at a predetermined speed in the direction of the arrow 56 by the rotational driving of the pressure roller 60 and the fixing belt 100A. In the present embodiment, as the fixing roller 50, a roller-like member formed in a cylindrical shape with a diameter of 30 mm including the core metal 51, the elastic body layer 52, and the surface layer 53 is used.

  As the metal forming the cored bar 51, a metal having high thermal conductivity can be used, and examples thereof include aluminum and iron. Examples of the shape of the core metal 51 include a cylindrical shape and a columnar shape, but a cylindrical shape with a small amount of heat released from the core metal 51 is preferable.

  The material constituting the elastic layer 52 is not particularly limited as long as it has rubber elasticity, but is preferably superior in heat resistance. Specific examples of such materials include silicone rubber, fluorine rubber, fluorosilicone rubber, and the like. Among these, silicone rubber having particularly excellent rubber elasticity is preferable. In the present embodiment, the surface layer 53 is provided on the elastic layer in order to correct the shift of the fixing belt 100A. However, the surface layer 53 may not be provided in other embodiments. Providing the surface layer 53 improves the slidability of the surface of the fixing roller 50 and makes it easy to correct the deviation of the fixing belt 100A.

  The material constituting the surface layer 53 is not particularly limited as long as it is excellent in heat resistance and durability and has high slidability. For example, PFA (a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether), A fluorine-based resin material such as PTFE (polytetrafluoroethylene), fluorine rubber, or the like can be used.

  A heating unit may be provided inside the fixing roller 50. This is because the start-up time from the power-on of the image forming apparatus 1 to be described later until image formation becomes possible is shortened, and the surface temperature of the fixing roller 50 is lowered due to the transfer of heat to the recording medium 8 during toner image fixing. This is to prevent the above.

  The heating roller 72 is a roller-like member that is rotatably supported and is provided so that tension can be applied to the fixing belt 100A by a pressure unit (not shown). The heating roller 72 rotates following the rotation of the fixing belt 100A in the direction of the arrow 78A. As the heating roller 72, a metal roller 80 made of a metal having high thermal conductivity such as aluminum or iron can be used. The metal roller 80 may have a fluororesin layer formed on the surface as necessary.

  The heating roller 72 has heating means 74 and 75 therein. As a result, the fixing belt 100A is heated. A power source (not shown) is connected to the heating means 74 and 75, and electric power for causing the heating means 74 and 75 to generate heat is supplied. As the heating means 74 and 75, a general heating means can be used.

  The pressure roller 60 is pressed against the fixing roller 50 via the fixing belt 100A by a pressure mechanism (not shown) on the downstream side in the rotation direction of the fixing roller 50 with respect to the lowest vertical point of the fixing roller 50, and the fixing nip 55 Form. The pressure roller 60 is rotationally driven by driving means (not shown). The pressure roller 60 promotes fixing of the toner image to the recording medium 8 by pressing the toner in a molten state against the recording medium 8 when the fixing roller 50 heat-fixes the toner image to the recording medium 8. To do.

  As the pressure roller 60, a roller-shaped member including a cored bar 61, an elastic body layer 62, and a surface layer 63 is used. As a material for forming the cored bar 61, the elastic body layer 62, and the surface layer 63, the same metal or material as that for forming the cored bar 51, the elastic body layer 52, and the surface layer 53 of the fixing roller 50 can be used. Further, the shape of the cored bar 61 is the same as that of the fixing roller 50.

  A heating unit 64 is provided inside the pressure roller 60. This is because the start-up time from when the power of the image forming apparatus 1 is turned on until the image can be formed is shortened, and the surface temperature of the pressure roller 60 is abrupt due to the transfer of heat to the recording medium 8 when fixing the toner image. This is to prevent a decrease or the like.

  As shown in FIG. 1, the part including the fixing roller 50 and the heating roller 72 is inclined at an angle of 45 °. With such a configuration, it is preferable that the toner on the recording medium 8 carrying the conveyed unfixed toner image is easily heated by the heat generated from the fixing belt 100A heated by the heating means 74 and 75.

  The thermistor 76 is provided close to the fixing belt 100A at a position facing the heating roller 72 via the fixing belt 100A, and detects the temperature of the fixing belt 100A. The detection result by the thermistor 76 is input to a CPU (Central Processing Unit) (not shown).

  The CPU determines from the detection result of the thermistor 76 whether the temperature of the thermistor 76 is within the set range. When the temperature of the fixing belt 100A is lower than the set range, a control signal is sent to the power source connected to the heating means 74, 75, and electric power is supplied to the heating means 74, 75 to promote heat generation. When the temperature of the fixing belt 100A is higher than the set range, the presence or absence of power supply to the heating means 74 and 75 is confirmed. When the power supply is continued, a control signal for stopping the power supply is sent.

  In addition, a thermostat 77 is provided at a position downstream of the thermistor 76 in the rotation direction of the fixing belt 100A so as to be close to the fixing belt 100A and detects an abnormal temperature rise of the fixing belt 100A. The detection result by the thermostat 77 is input to the CPU. The CPU stops the power supply from the power source connected to the heating means 74 and 75 according to the detection result of the thermostat.

  A fixing mechanism including the fixing roller 50, the heating roller 72, the fixing belt 100 </ b> A, and the pressure roller 60 is controlled by a CPU that controls all operations of the image forming apparatus 1.

  When receiving an input of an image formation instruction, the CPU sends a control signal to a power source (not shown) that supplies power to the heating means 74, 75, and 64 provided inside the heating roller 72 and the pressure roller 60. The image forming instruction is input from an operation panel (not shown) provided on the upper surface in the vertical direction of the image forming apparatus 1 or an external device such as a computer connected to the image forming apparatus 1. The power supply that has received the control signal supplies power to activate the heating means 74, 75, 64.

  The heating means 74, 75, and 64 heat the fixing roller 50, the heating roller 72, the pressure roller 60, and the surface of the fixing belt 100A so as to have respective set temperatures. When a temperature detection sensor (not shown) provided in the vicinity of the fixing roller 50 and the pressure roller 60 detects that the set temperature has been reached and the detection result is input to the CPU, the CPU rotates the fixing roller 50. A control signal is sent to the drive means that does not, and the pressure roller 60 is driven to rotate in the direction of the arrow 56. Accordingly, the fixing belt 100A, the fixing roller 50, and the heating roller 72 are driven to rotate. In this state, the recording medium 8 carrying the unfixed toner image is conveyed from the secondary transfer roller 31 to the fixing nip portion 55. When the recording medium 8 passes through the fixing nip 55, the toner constituting the toner image is heated and pressurized and fixed on the recording medium 8 to form an image.

(Configuration of fixing belt 100A)
FIG. 2 is an enlarged cross-sectional view of section S101-S101 of fixing belt 100A shown in FIG. The fixing belt 100A as a fixing member is an endless belt having a three-layer structure, and includes a release layer 102A, an elastic layer 83, and a support layer 84 as a core material.

  The release layer 102A is formed by curing a coating material in which a crosslinked fluororesin and an uncrosslinked fluororesin are mixed at a ratio of 30:70 to 70:30. The uncrosslinked fluororesin has a melting point of 250 ° C. The temperature is 300 ° C. or less and the melt flow index is 5 g / 10 min or more and 25 g / 10 min or less.

  Since the high temperature offset region of the toner is in the range of 230 ° C. or more and 250 ° C. or less, if the melting point of the uncrosslinked fluororesin is less than 250 ° C., the release layer 102A of the fixing member also melts simultaneously with the heating of the toner during fixing. To do. The higher the melting point of the resin used for the release layer 102A, the higher the elastic modulus of the release layer 102A. Therefore, when the melting point of the uncrosslinked fluororesin exceeds 300 ° C., the flexibility of the fixing member as a surface layer material is poor. When the toner is melted at the time of fixing, it becomes difficult for the toner to follow the unevenness of the recording medium and fix, and the fixability is lowered.

  If the melt flow index of the uncrosslinked fluororesin is less than 5 g / 10 min, which is the same as that of conventional fluororesin tubes, the surface layer material is inferior in flexibility, and the toner follows the unevenness of the paper when the toner melts during fixing. It becomes difficult to fix. When the melt flow index of the uncrosslinked fluororesin exceeds 25 g / 10 min, the aging resistance of the release layer 102A is deteriorated and the durability of the fixing member is deteriorated.

  In the mixing ratio of the cross-linked fluororesin and the non-crosslinked fluororesin, if the cross-linked fluororesin is less than the specified value and the uncrosslinked fluororesin is mixed more than the specified value, the durability of the fixing member is deteriorated. If the amount of the cross-linked fluororesin is greater than the specified value and the amount of the uncrosslinked fluororesin is less than the specified value, the release layer 102A has an undesirably high elastic modulus. The toner is less likely to be fixed following the unevenness of the recording medium.

  By mixing the crosslinked fluororesin and the uncrosslinked fluororesin having the melt flow index and melting point as described above at a ratio of 30:70 to 70:30, the crosslinked fluororesin and the uncrosslinked fluororesin are in an appropriate ratio. The release layer 102A can be sufficiently mixed, and the elastic modulus can be lowered while maintaining the durability of the fixing member as compared with the case where the resin contained in the coating material is only a crosslinked fluororesin. Therefore, it is possible to obtain a fixing member that is highly flexible and excellent in durability so that the toner can be sufficiently fixed on the recording medium.

  The cross-linked fluororesin used for the release layer 102A is not particularly limited as long as it has excellent heat resistance and durability and weak adhesion to the toner. For example, cross-linked PTFE (polytetrafluoroethylene manufactured by Hitachi Cable Finetech Co., Ltd.) Fluoroethylene). Examples of the uncrosslinked fluororesin having the melt flow index and the melting point include tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA, crystal melting point 250 to 290 ° C.) manufactured by Mitsui Dupont Chemical Co., Ltd.

  In this way, the release layer 102A can be coated with a flexible fluororesin having a low melting point and a high melt flow index, which could not be used in a conventional fluororesin tube, so that the selection of materials is possible. The effect of maintaining the durability with a wide width and excellent flexibility can be achieved at a lower cost than before.

  The thickness of the release layer is preferably 5 μm or more and 30 μm or less. When the thickness of the release layer is less than 5 μm, the deterioration of the release layer is likely to proceed when cracks, scratches, and wear occur during fixing. When the thickness of the release layer exceeds 30 μm, the flexibility of the release layer is inferior, and when the toner is melted, it becomes difficult for the toner to follow the unevenness of the recording medium and be fixed. When the thickness of the release layer is 5 μm or more and 30 μm or less, it is possible to follow the minute irregularities of the recording medium while making use of the elasticity of the elastic layer, and to obtain a fixing member having further excellent flexibility and durability. be able to.

  The release layer has a surface roughness Ra of 0.3 μm or less. When the surface roughness Ra exceeds 0.3 μm, irregularities on the surface of the release layer appear in the toner image after fixing. When the surface roughness Ra of the release layer is 0.3 μm or less, a fixing member having excellent smoothness can be obtained. The surface roughness Ra of the release layer was measured using Surfcoder SE3500 (Kosaka Laboratory).

  The material constituting the elastic layer 83 is not particularly limited as long as it has rubber elasticity, but is preferably superior in heat resistance. Specific examples of such materials include silicone rubber, fluorine rubber, fluorosilicone rubber, and the like. Among these, silicone rubber having particularly excellent rubber elasticity is preferable.

  The elastic layer 83 preferably has a JIS-A hardness of 1 to 60 degrees. Within this JIS-A hardness range, it is possible to prevent poor toner fixability while preventing a decrease in strength of the elastic layer 83 and poor adhesion. Specifically, one-component, two-component or three-component or more silicone rubber, LTV type, RTV type or HTV type silicone rubber, condensation type or addition type silicone rubber can be used as the silicone rubber. .

  The thickness of the elastic layer 83 is preferably 30 to 500 μm. If it is this thickness range, heat insulation can be restrained low, maintaining the elastic effect of the elastic layer 83, and the energy saving effect can be exhibited.

  The material constituting the support layer 84 is not particularly limited as long as it is excellent in heat resistance and durability, but heat-resistant synthetic resins can be raised, and among them, polyimide (PI), polyamideimide (PAI), etc. preferable. These resins are excellent in strength, heat resistance, price and the like.

  The thickness of the support layer 84 is not particularly limited, but is preferably 30 to 200 μm.

  Here, the thicknesses of the release layer, the elastic layer, and the support layer of the fixing belt 100A can be obtained as follows.

  A section of the fixing belt is embedded in an epoxy resin, etc., surfaced by cutting with a microtome, and an enlarged photograph is taken between 100 times and 2000 times with a scanning electron microscope (SEM). Measure the thickness of the mold layer, elastic layer and support layer.

  Since the fixing roller 100A having such a configuration is incorporated to form the fixing device 6A, the toner can be smoothly melted and released during fixing, and a highly glossy image can be stably formed. can do.

(Fabrication method of fixing belt 100A)
In order to manufacture the fixing belt 100A, a highly accurate mold or mold is first required. The material constituting the support layer 8 is applied to the outer peripheral surface of the mold or mold, and the support layer 8 is formed by baking.

  After cooling the mold on which the support layer 8 is formed to room temperature, the material constituting the elastic layer 83 is applied to the outer peripheral surface of the mold and baked to form the elastic layer 83.

  After cooling the mold on which the support layer 84 and the elastic layer 83 are formed to room temperature, a coating agent in which a cross-linked fluororesin and an uncrosslinked fluororesin are mixed in advance is applied to the outer peripheral surface of the mold, and the uncrosslinked fluororesin is applied. The uncrosslinked fluororesin is melted at a firing temperature sufficiently higher than the melting point of the coating to perform coating, thereby forming the release layer 102A.

  After the mold on which the elastic layer 83, the support layer 84, and the release layer 102A are formed is cooled to room temperature, the manufactured annular material is removed from the mold to obtain the fixing belt 100A.

  The firing temperature when forming the elastic layer 83, the support layer 84, and the release layer 102A is preferably 250 ° C. or higher and 380 ° C. or lower, and more preferably 250 ° C. or higher and 350 ° C. or lower. In addition, since the crosslinking reaction of the fluororesin occurs by a special treatment such as radiation crosslinking, the uncrosslinked fluororesin is not crosslinked by firing, and the ratio of the crosslinked fluororesin to the uncrosslinked fluororesin before and after firing is does not change.

  As an apparatus for firing the release layer 102A and the like in this way, for example, a general coating apparatus such as a batch-type high-temperature heating furnace, an electric furnace, or an electrostatic powder coating machine can be cited.

  In this way, an uncrosslinked fluororesin having a melting point of 250 ° C. or more and 300 ° C. or less and a melt flow index of 5 g / 10 min or more and 25 g / 10 min or less is used. The fixing material 100A is manufactured by curing the coating material mixed at a ratio of ˜70: 30 to form the release layer 102A, so that the crosslinked fluororesin and the uncrosslinked fluororesin are sufficiently mixed at an appropriate ratio. Compared with the method of manufacturing the release layer 102A using only the cross-linked fluororesin as the resin contained in the coating material, the combined release layer 102A can be formed, and the fixing belt 100A is elastic while maintaining the durability. The ratio can be lowered, so that the toner can be sufficiently fixed on the recording medium, and the fixing is highly flexible and excellent in durability. It can be obtained belt 100A.

  The fixing member of the present invention thus manufactured is not limited to being used in the fixing device as in the present embodiment, and can be used in various types of fixing devices. Hereinafter, Embodiments 1B to 1D in which the fixing member of the present invention is used in a fixing device other than 1A will be described.

(2) Embodiment 1B (Configuration of Fixing Device 6B)
FIG. 3 is a cross-sectional view schematically showing a configuration of the fixing roller 100B according to the first embodiment of the present invention and a fixing device 6B in which the fixing roller 100B is incorporated. As shown in FIG. 3, the fixing device 6 </ b> B includes a fixing roller 100 </ b> B, a pressure roller 60, and an external heating unit 70. In the drawings subsequent to FIG. 3, members having the same configurations as those of the 1A embodiment are denoted by the same reference numerals as those of the 1A embodiment, and description thereof may be omitted. In the first embodiment, the fixing member is the fixing belt 100A, but in this embodiment, the fixing member is the fixing roller 100B.

The fixing roller 100B is a roller-like member that is rotatably supported by a support unit (not shown) and that rotates at a predetermined speed in the direction of an arrow 78B by a drive unit (not shown).
The fixing roller 100 </ b> B heats and melts the toner constituting the toner image carried on the recording paper 8 to fix it on the recording paper 8.

  A heat source 54 is provided inside the fixing roller 100B. This is because the start-up time from when the image forming apparatus 100 is turned on until the image can be formed is shortened, and the surface temperature of the fixing roller 100B is lowered due to the transfer of heat to the recording paper 8 when the toner image is fixed. This is to prevent it.

  The pressure roller 60 is a roller-like member that is rotatably provided in a state in which the pressure roller 60 is in pressure contact with the fixing roller 100B by a pressure mechanism (not shown) on the downstream side in the rotation direction of the fixing roller 100B with respect to the lowest vertical point of the fixing roller 100B. It is. A pressure contact portion between the fixing roller 100 </ b> B and the pressure roller 60 is a fixing nip portion 55. The pressure roller 60 rotates following the rotation of the fixing roller 100B. The pressure roller 60 promotes fixing of the toner image to the recording paper 8 by pressing the toner in a molten state against the recording paper 8 when the fixing roller 100B heat-fixes the toner image to the recording paper 8. To do.

  In the present embodiment, a roller-like member having a diameter of 40 mm including a cored bar 61, an elastic body layer 62, and a surface layer 63 is used as the pressure roller 60. As materials for forming the cored bar 61, the elastic body layer 62, and the surface layer 63, the same materials as those for the pressure roller 60 of the first embodiment A can be used. The shape of the cored bar 61 is the same as that in the first embodiment. A heating unit 64 is provided inside the pressure roller 60.

  The external heating means 70 includes an endless belt 171, a first support roller 172, a second support roller 173, thermistors 76 and 178, and a thermostat 77. The endless belt 171 is an endless belt-like member that is stretched between the first support roller 172 and the second support roller 173 to form a loop-shaped movement path. The endless belt 171 has a length in the outer circumferential direction of the fixing roller 100B between the pressure contact between the first support roller 172 and the fixing roller 100B and the pressure contact between the second support roller 173 and the fixing roller 100B, and the fixing roller. It is provided so as to come into contact with the fixing roller 100B in a band-like region extending in the longitudinal direction of 100B. The endless belt 171 is driven to rotate in the direction of the arrow 179 by the rotational drive of the fixing roller 100B in the direction of the arrow 78B. The endless belt 171 is not particularly limited as long as it has excellent heat resistance and durability, and examples thereof include a polyimide belt and a nickel electroformed belt. A fluororesin layer such as PFA or PTFE may be formed on the surface of the endless belt 171.

  The first support roller 172 and the second support roller 173 are roller-like members that are rotatably supported and are pressed against the surface of the fixing roller 100B via an endless belt 171 by a pressing unit (not shown). The first support roller 172 and the second support roller 173 rotate following the rotation of the endless belt 171 in the direction of the arrow 179.

  As the first support roller 172 and the second support roller 173, a metal roller made of a metal having high thermal conductivity such as aluminum or iron can be used. The metal roller may have a fluororesin layer formed on the surface thereof as necessary. The first support roller 172 and the second support roller 173 have heat sources 174 and 175 therein. As a result, the endless belt 171 and thus the fixing roller 100B are heated. A power source is connected to the heat sources 174 and 175, and electric power for causing the heat sources 174 and 175 to generate heat is supplied. A general heat source can be used as the heat sources 174 and 175. In this embodiment, halogen lamps are used for the heat sources 174 and 175. The first support roller 172 and the second support roller 173 are provided on the fixing roller 100B so that their axes are parallel to each other and are separated from each other with a gap.

  The thermistor 76 is provided so as to be close to the endless belt 171 at a position facing the second support roller 173 via the endless belt 171. The thermistor 76 is a portion of the endless belt 171 in contact with the second support roller 173. A second temperature, which is a temperature, is detected.

  The thermistor 178 is provided so as to be close to the endless belt 171 at a position facing the first support roller 172 via the endless belt 171. The thermistor 178 is a portion of the endless belt 171 in contact with the first support roller 172. A second temperature, which is a temperature, is detected.

  The thermostat 77 is provided to face the second support roller 173 via the endless belt 171 and to be close to the endless belt 171 at a position downstream of the thermistor 76 in the rotational direction of the endless belt 171. Detects abnormal temperature rise.

  The fixing device 6B is controlled by a CPU (not shown) as in the first embodiment. That is, the fixing mechanism including the fixing roller 100B, the pressure roller 60, and the external heating means 70 is controlled by the CPU. When receiving an image formation instruction, the CPU supplies power to the heat sources 54, 64, 174, and 175 provided in the fixing roller 100B, the pressure roller 60, and the first and second support rollers 172 and 173. Send a control signal to. The image forming instruction is input from an operation unit 7 provided on the upper surface of the image forming apparatus 1 or an external device such as a computer connected to the image forming apparatus 1 via a LAN. The power supply that has received the control signal supplies power to activate the heat sources 54, 64, 174, and 175.

  The heat sources 54, 64, 174, and 175 heat the surfaces of the fixing roller 100B, the pressure roller 60, and the endless belt 171 so as to have respective set temperatures. When a temperature detection sensor such as the thermistor 76 provided in the vicinity of the fixing roller 100B and the pressure roller 60 detects that the set temperature has been reached and the detection result is input to the CPU, the CPU drives the fixing roller 100B to rotate. A control signal is sent to a driving means (not shown) to rotate the fixing roller 100B in the direction of the arrow 78B. Accordingly, the pressure roller 60 and the endless belt 171 are driven to rotate. In this state, the recording paper 8 carrying the unfixed toner image is conveyed to the fixing nip portion 55. When the recording paper 8 passes through the fixing nip portion 55, the toner constituting the toner image is heated and pressurized and fixed on the recording paper 8 to form an image.

  The detection result by the thermostat 77 is input to the CPU via the fixing unit control circuit of the control unit. The CPU stops the power supply from the power source connected to the heat sources 174 and 175 according to the detection result of the thermostat 77.

  As a result of temperature detection by the thermistors 76 and 178, that is, the first temperature which is the temperature of the endless belt 171 where the endless belt 171 is in contact with the first support roller 172, and the endless belt 171 are in contact with the second support roller 173. The second temperature, which is the temperature of the endless belt 171, is input to the CPU via the fixing unit control circuit of the control unit.

  As described above, the heat source 174 and the heat source 175 are provided inside the first support roller 172 and the second support roller 173. A power source is connected to the heat source 174 and the heat source 175, and the power is supplied by a fixing unit control circuit of the control unit.

  The control unit of the image forming apparatus 1 receives the fixing command, rotates the fixing roller 100B, passes the recording paper 8 through the nip portion, and finishes the fixing operation. Then, the control unit of the image forming apparatus 1 applies the first support roller 172 and the second support roller 173 to each other. The electric power supplied to the heat source 174 and the heat source 175 provided is stopped, the fixing roller 100B is rotated for a predetermined time, and then the rotation is performed. Thereafter, the rotation of the fixing roller 100B is stopped.

  As described above, the temperature of the endless belt 171 where the endless belt 171 is in contact with the first support roller 172 is used as the first temperature, and the endless belt 171 is in contact with the second support roller 173 as the second temperature. The temperature of the endless belt 171 is used, but the temperature of the first support roller 172 in contact with the first support roller 172 is used as the first temperature, and the endless belt is used as the second temperature. The temperature of the portion of the second support roller 173 that is in contact with the second support roller 173 may be used.

  Although the external heating means 70 is included in this embodiment, the external heating means 70 may not be included in other embodiments.

(Configuration of Fixing Roller 100B)
The fixing roller 100B is a roller-like member including a cored bar 51, an elastic body layer 52, and a release layer 102B. Since the configuration of the core metal 51 and the elastic layer 52 is the same as that of the fixing roller 50 of the first embodiment, the description thereof is omitted.

  The release layer 102B is made of a coating material in which a crosslinked fluororesin and an uncrosslinked fluororesin are mixed at a ratio of 30:70 to 70:30 in the same manner as the release layer 102A of the 1A embodiment. The uncrosslinked fluororesin has a melting point of 250 ° C. or more and 300 ° C. or less and a melt flow index of 5 g / 10 min or more and 25 g / 10 min or less. As a result, a release layer in which a cross-linked fluororesin and an uncrosslinked fluororesin are sufficiently mixed at an appropriate ratio can be obtained, and compared with the case where the resin contained in the coating material is only the cross-linked fluororesin. Since the elastic modulus can be lowered while maintaining the durability of the member, it is possible to obtain a fixing member that is highly flexible and excellent in durability so that the toner can be sufficiently fixed on the recording medium.

  The thickness and surface roughness Ra of the release layer 102B are the same as those of the release layer 102A of the 1A embodiment.

  Here, the thicknesses of the release layer, the elastic layer, and the support layer of the fixing roller 100B can be obtained as follows.

  The elastic layer of the fixing roller is cut out as a section including a release layer, embedded in an epoxy resin, etc., surfaced by cutting with a macrotome, and then observed with an SEM to release the release layer. Measure the thickness. The thickness of the support layer can be determined by measuring with a commercially available micrometer before manufacturing the fixing roller. For the elastic layer, the diameter of the fixing roller after coating the release layer was measured using a commercially available micrometer, and the value of twice the thickness of the release layer from the diameter of the fixing roller and the thickness of the support layer were measured. The value obtained by subtracting can be divided by 2.

(Method for producing fixing roller 100B)
To manufacture the fixing roller 100B, first, a highly accurate mold or mold is required. A coating agent in which a cross-linked fluororesin and an uncrosslinked fluororesin are mixed in advance is applied to the inner surface of the mold or mold, and the uncrosslinked fluororesin is melted at a firing temperature sufficiently higher than the melting point of the uncrosslinked fluororesin. Then, coating is performed to form a release layer 102B.

  Next, a metallic hollow core metal core is prepared. After the mold on which the release layer 102B is formed is cooled to room temperature, the hollow core metal core is inserted into the mold, and the material constituting the elastic layer 52 is poured between them in a liquid state and fired. As a material constituting the elastic layer 52, a material constituting the elastic layer 83 can be used.

  The firing temperature when forming the release layer 102B and the elastic layer 52 is the same as the firing temperature when forming the elastic layer 83, the support layer 84, and the release layer 102A.

  As an apparatus for firing the release layer 102B and the like in this way, for example, a general coating apparatus such as a batch type high-temperature heating furnace, an electric furnace, or an electrostatic powder coating machine can be cited.

(3) First C Embodiment FIG. 4 incorporates a first fixing roller 100C and a second fixing roller 100c, and a first fixing roller 100C and a second fixing roller 100c, which are the first C embodiment of the present invention. 2 is a cross-sectional view schematically showing a configuration of a fixing device 6C. The fixing device 6C includes a first fixing device 6C1 including a first fixing roller 100C, a first pressure roller 60C, a web cleaning device 110, and an external heating device 70, and a second fixing roller 100c and a second pressure roller 60c. And a first fixing device 6C2. The fixing device 6C is a tandem fixing device. In the present embodiment, the first fixing roller 100C and the second fixing roller 100c correspond to fixing members, and the configuration of the release layer 102C is the same as the configuration of the release layer 102B in the second B embodiment.

(First fixing device 6C1)
The first fixing roller 100C is a roller that rotates in the 78C direction shown in FIG. 4, and covers a metal hollow cylindrical cored bar 51C, an elastic layer 52C that covers the outer peripheral surface of the cored bar 51C, and an elastic layer 52C. This is a three-layer structure composed of a release layer 102C formed in this manner.

  The metal core 51C has an outer diameter of 46 mm and is made of aluminum. The core metal 51C is not limited to aluminum, and may be made of a metal such as iron, stainless steel, or copper, or an alloy thereof. The elastic layer 52C has a thickness of 3 mm and is made of heat-resistant silicone rubber. The surface hardness of the first fixing roller 100C thus configured is 68 degrees (Asker C hardness).

  The thermistor C that detects the temperature of the first fixing roller 100C is in contact with the peripheral surface of the first fixing roller 100C. A heater lamp c that radiates infrared rays (performs heat radiation) by being energized from a control circuit 126 described later is installed inside the core bar 51C. When the heater lamp c is energized, the inner surface of the first fixing roller 100C absorbs infrared rays by the heater lamp c, and the entire first fixing roller 100C is heated.

  The first pressure roller 60C is a roller that rotates in the 56C direction, and is a metal hollow cylindrical cored bar, an elastic layer that covers the outer peripheral surface of the cored bar, and a release layer that is formed by covering the elastic layer Consists of

  The core bar 61C has an outer diameter of 46 mm and is made of aluminum. The core bar 61C is not limited to aluminum, and may be made of a metal such as iron, stainless steel, or copper, or an alloy thereof. The elastic layer 62C has a thickness of 2 mm and is made of heat-resistant silicone rubber. The surface layer 63C is made of a PFA tube having a thickness of about 30 μm. As the material of the surface layer 62C, any material may be used as long as it has excellent heat resistance and durability, and excellent releasability from the toner. In addition to PFA, a fluorine-based material such as PTFE may be used. The surface pressure of the first pressure roller 60C thus configured is 75 degrees (Asker C hardness).

  The thermistor D for detecting the temperature of the peripheral surface is in contact with the peripheral surface of the first pressure roller 60C, and infrared rays are emitted into the cored bar 61C by being energized from the control circuit 126 ( A heater lamp d (which performs thermal radiation) is installed. The heater lamp d is a heat source for the first pressure roller 60C. When the heater lamp d is energized, the inner peripheral surface of the first pressure roller 60C absorbs infrared rays by the heater lamp d, and the entire first pressure roller 60C is heated.

  The first fixing roller 100C and the first pressure roller 60C have an outer diameter of 50 mm, and are pressed against each other with a predetermined load (600 N in this case) by an elastic member (spring) (not shown). As a result, a fixing nip portion 55C is formed between the peripheral surface of the first fixing roller 100C and the peripheral surface of the first pressure roller 60C. The fixing nip portion 55C is a portion where the first fixing roller 100C and the first pressure roller 60C are in contact with each other, and is 9 mm in this embodiment. The first fixing roller 100C is heated to a predetermined temperature (here, 180 ° C.), and the recording medium 8 passes through the fixing nip portion 55C, whereby the toner image is fixed. When the recording medium 8 passes through the fixing nip 55C, the first fixing roller 100C contacts the toner image forming surface of the recording medium 8, and the first pressure roller 60C is opposite to the toner image forming surface of the recording medium 8. Contact the surface.

  A drive motor (drive means) (not shown) that rotationally drives the first fixing roller 100C is provided so that the recording medium 8 passes through the fixing nip portion 55C. The first pressure roller 60C rotates following the rotation (in the 78C direction) of the first fixing roller 100C (in the 56C direction). That is, the first fixing roller 100C and the first pressure roller 60C rotate in opposite directions.

  The recording medium 8 is conveyed to the fixing nip 55C at a predetermined fixing speed and copying speed according to the rotation speed of the first fixing roller 100C by the drive motor, and unfixed toner is fixed to the recording medium 8 by heat and pressure. The Here, the fixing speed is a so-called process speed, for example, 355 mm / sec, and the copying speed is the number of copies per minute, for example, 70 sheets / minute.

  The web cleaning device 110 cleans the first fixing roller 100C. The web cleaning device 110 includes a cleaning web 81, a feed roller 82, a web pressing roller 85, and a winding roller 86, and removes offset toner and the like attached to the surface of the first fixing roller 100C.

  The cleaning web (hereinafter also simply referred to as “web”) 81 is fed from the feed roller 82 toward the web pressing roller 83 in the direction of the arrow 81a, wound around the web pressing roller 85, and the surface of the first fixing roller 100C. After being in pressure contact with each other, the take-up roller 86 is provided to be taken up.

  For the web 81, for example, a heat-resistant nonwoven fabric can be used. Although it does not restrict | limit especially as a heat-resistant nonwoven fabric, For example, the nonwoven fabric etc. which have a moderate softness | flexibility and mechanical strength including an aromatic polyamide fiber and the polyester fiber softened at high temperature are mentioned. Such heat-resistant nonwoven fabrics are commercially available, and examples thereof include Nomex (trade name) and Himeron (trade name).

  The feed roller 82 is supported so as to be able to be driven and rotated around the axis, and the web 81 is wound around and held on the surface thereof. In the present embodiment, the feed roller 82 is provided so as to be separated from the external heating means 70 substantially vertically above the external heating means 70. Further, in the present embodiment, the feeding roller 82 is configured to rotate in the counterclockwise direction following the winding operation of the web 81 by the winding roller 86 and send out the web 81.

  The web pressure contact roller 85 is a roller-like member that is rotatably supported at both ends in the longitudinal direction by a bearing (not shown). The web pressure roller 85 is provided so as to be in pressure contact with the surface of the fixing roller 50 via the web 81 by a pressing unit (not shown). The web pressure roller 85 is driven and rotated during the winding operation of the web 81 by the winding roller 86.

  For the web pressure roller 85, for example, a roller-shaped member including a metal core and an elastic layer formed on the surface of the metal core is used. As an elastic material which comprises an elastic layer, heat resistant rubbers, such as silicone rubber, its foam etc. are mentioned, for example. The surface hardness of the elastic layer is not particularly limited, but is preferably 20 ° to 30 ° (Asker-c, Asker C hardness).

  The external heating means 70 includes a first support roller 172, a second support roller 173, an endless belt 171 and thermistors A and B.

  Endless belt 171 is heated to a predetermined temperature (here, 210 ° C., for example), and the surface side comes into contact with the surface of first fixing roller 100C to heat the surface of first fixing roller 100C. . The endless belt 171 is suspended on each support roller such that the back surface side comes into contact with the peripheral surfaces of the first support roller 172 and the second support roller 173.

  The endless belt 171 is provided on the upstream side of the fixing nip portion 55C in the first fixing roller 100C. The endless belt 171 is pressed against the peripheral surface of the first fixing roller 100C with a predetermined pressing force (40N in this case). Thus, a nip portion (hereinafter referred to as a heating nip portion) 111 is formed between the surface of the endless belt 171 and the first fixing roller 100C peripheral surface, and the surface of the endless belt 171 is formed on the first fixing roller 100C peripheral surface. Will be in contact. The nip width of the heating nip 111 between the surface of the endless belt 171 and the peripheral surface of the first fixing roller 100C is 20 mm (a width along the circumferential direction of the first fixing roller 100C). When the first fixing roller 100C rotates, the endless belt 171 circulates following the first fixing roller 100C, and the endless belt 171 follows the circulatory movement of the endless belt 171 so that the first support roller 172 and the second support roller 173 also move. It is configured to rotate.

  The endless belt 171 was coated on the surface of a hollow cylindrical base material made of polyimide in which carbon black having a thickness of 90 μm was dispersed with a fluorine resin mixed with PTFE and PFA as a surface layer at a thickness of 10 μm. It has a two-layer structure. In addition to polyimide, the base material constituting the two-layer structure may be a heat-resistant resin or a metal material such as stainless steel, nickel, or iron. The surface layer may be a synthetic resin material (for example, a fluororesin such as PFA or PTFE) having excellent heat resistance and releasability from the toner. Further, in order to reduce the shifting force of the endless belt 171, the inner surface of the base material of the endless belt 171 may be coated with a fluorine resin or the like.

  The first support roller 172 and the second support roller 173 are rollers formed of an aluminum hollow cylindrical cored bar having an outer diameter of 15 mm and a wall thickness of 1 mm. The core metal is not limited to aluminum and may be an iron-based material. The first support roller 172 and the first support roller 172 may be used as necessary when the frictional force between the back surface of the endless belt 171 and the peripheral surfaces of the first support roller 172 and the second support roller 173 is reduced to reduce the shifting force due to meandering. The two support rollers 173 may have a configuration in which a release layer is provided on the cored bar. As a material for the release layer, it is only necessary to have excellent heat resistance and durability, and excellent release properties from the toner, and fluorine-based materials such as PFA and PTFE (polytetrafluoroethylene) are used.

  In the external heating means 70, the thermistors A and B for detecting the temperature of the endless belt 171 are in contact with the surface of the endless belt 171.

  Inside the first support roller 172, there is provided a heater lamp (heating means) a that generates heat by supplying power. The heater lamp a is a heat source for the endless belt 171. When the heater lamp a is energized, the heater lamp a emits light and radiates infrared rays. Similarly, a heater lamp (heating means) b that generates heat by supplying power is provided inside the second support roller 173. The heater lamp b is a heat source for the endless belt 171. When the heater lamp b is energized, the heater lamp b emits light and radiates infrared rays. Accordingly, the inner peripheral surfaces of the first support roller 172 and the second support roller 173 are heated, and the endless belt 171 is indirectly heated via the first support roller 172 and the second support roller 173.

  When a wide heating nip width between the first fixing roller 100C and the endless belt 171 is ensured, there is a limit to bridging the endless belt 171 with only two support rollers. Although 171 is applied to two support rollers, a configuration in which a tension roller is separately provided and applied to three or more rollers as necessary may be employed.

  FIG. 5 is a block diagram regarding control of members related to heating of the fixing roller 6C. FIG. 5 shows the relationship between the thermistors A to F, the control circuit 126, and the heater lamps a to f. As shown in FIG. 5, the control circuit 126 serving as the temperature control means is configured based on the temperature data detected by each of the thermistors A, B, C, and D, and the first fixing roller 100C, the first pressure roller 60C, and the outside. Energization of the heater lamps a, b, c, and d is controlled via the power supply circuit so that the heating means 70 has a predetermined temperature.

  In FIG. 4, the external heating means 70 is provided only for the first fixing roller 100C. However, the external heating means may be provided for both the first fixing roller 100C and the first pressure roller 60C. Good.

(Second fixing device 6C2)
The second fixing roller 100c includes a hollow cylindrical core metal 51c made of aluminum having an outer diameter of 46 mm, an elastic layer 52c made of silicone rubber having a thickness of 3 mm and covering the outer peripheral surface of the core metal 51c, and an elastic layer. A roller-shaped member having a three-layer structure including a release layer 102c formed so as to cover 52c and having the same configuration as the release layer 102C. The surface hardness of the second fixing roller 100c is 68 degrees (Asker C hardness).

  A thermistor E for detecting the temperature of the peripheral surface of the second fixing roller 100c is disposed on the peripheral surface of the second fixing roller 100c. A heater lamp e that is a heat source of the second fixing roller 100c is provided inside the second fixing roller 100c, and the entire second fixing roller 100c is heated by the heater lamp e. In the present embodiment, a 1000 W halogen lamp is used as the heater lamp e. The second heating roller rotates in the I direction shown in FIG.

  The second pressure roller 60c includes a hollow cylindrical cored bar 61c made of aluminum having an outer diameter of 46 mm, an elastic layer 62c made of silicone rubber having a thickness of 2 mm and covering the outer peripheral surface of the cored bar 61c, an elastic layer The surface layer 63c is formed of a PFA (copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether) tube having a thickness of about 30 μm formed by covering 62c. The surface pressure of the second pressure roller 60c thus configured is 75 degrees (Asker C hardness).

  A thermistor F for detecting the temperature of the peripheral surface of the second pressure roller 60c is provided in contact with the peripheral surface of the second pressure roller 60c. A heater lamp f, which is a heat source for the second pressure roller 60c, is provided inside the second pressure roller 60c, and the entire second fixing roller 100c is heated by the heater lamp f. In this embodiment, a 1000 W halogen lamp is used as the heater lamp e. The second pressure roller 60c rotates in the 56c direction shown in FIG.

  Similar to the first fixing roller 100C and the second pressure roller 60c, the second fixing roller 100c and the second pressure roller 60c have an outer diameter of 50 mm, and a predetermined load is applied by an elastic member (spring) not shown. (Here, 600N) they are pressed together. As a result, a fixing nip portion 55c is formed between the peripheral surface of the second fixing roller 100c and the peripheral surface of the second pressure roller 60c.

  A drive motor (drive means) (not shown) that rotationally drives the second fixing roller 100c is provided so that the recording medium 8 passes through the fixing nip portion 55c. The second pressure roller 60c rotates (in the 56c direction) following the rotation of the second fixing roller 100c (in the 78c direction).

  As shown in FIG. 5, the control circuit as the temperature control means normally has the predetermined temperature of the second fixing roller 100c and the second pressure roller 60c based on the temperature data detected by the thermistors E and F. The energization to the heater lamps e and f is controlled through the power supply circuit.

  The first fixing device 6C1 and the first fixing device 6C2 are arranged vertically along the conveyance direction of the recording medium 8, and a conveyance guide plate (not shown) is provided between the both devices. The recording medium 8 fixed by the first fixing device is conveyed along the guide member, introduced into the nip portion 55c of the first fixing device 6C2, subjected to fixing processing, and discharged.

  In the fixing device 6C configured as described above, as described in Japanese Patent Application Laid-Open No. 2005-352389, the temperature of the first fixing device 6C2 is controlled so as to compensate for the temperature variation of the first fixing device 6C1 (gross). Control is performed so that the gloss of the image in continuous paper passing (continuous fixing processing) is substantially uniform.

  First, a relational expression of the temperatures of the first fixing roller 100C and the second fixing roller 100c is obtained as described in the above publication so that the gloss of the plurality of images to be output is substantially uniform. That is, by controlling the temperature of the second fixing roller 100c so that the temperature of the first fixing roller 100C becomes the temperature obtained by the above relational expression, regardless of the temperature of the first fixing roller 100C. An image having a certain gloss is obtained.

  The temperature control means of the first fixing device 6C2 uses the difference T1-T2 between the surface temperature T1 of the first fixing roller 100C detected by the thermistor C and the target temperature setting value T2 of the first fixing roller 100C as the first fixing roller 100C. When the temperature fluctuation value α exceeds the temperature ripple in the temperature adjustment when the first fixing roller 100C is not passing paper, control in the gloss correction temperature adjustment mode is performed. If the target set temperature in the normal state of the second fixing roller 100c is T4, the temperature correction value β of the second fixing roller 100c is added to the target set temperature T4 of the second fixing roller 100c in the gloss correction temperature adjustment mode. The temperature of the second fixing roller 100c is controlled with the value (T4 + β).

  The temperature control means of the first fixing device 6C2 performs the temperature control by substituting the surface temperature (T2 + α) of the first fixing roller 100C into the above relational expression to obtain the control temperature (T4 + β) of the second fixing roller 100c.

  The gloss correction temperature adjustment mode ends when the continuous fixing process ends or when the temperature fluctuation value α of the first fixing roller 100C becomes a predetermined value or less, and control in the normal mode is performed.

  In the above, an example of the fixing device including the external heating device 70 using the endless belt 171 is shown as the first fixing device 6C1, but the external heating device 70 is not the endless belt 171 but a roller type. Also good. In addition, although an example using a fixing device including an external heating device and a roller type fixing device is shown as a fixing device, a belt fixing device using a belt or an induction heating fixing device using induction heating may be used. Alternatively, these may be combined as appropriate.

(4) First D Embodiment FIG. 6 is a cross-sectional view schematically showing a configuration of a fixing belt 102D according to a first D embodiment of the present invention and a fixing device 6D incorporating the fixing belt 100D. . The fixing device 6D includes a fixing belt 102D as a first endless belt, a pressure belt 160 as a second endless belt, a fixing unit 150, and a pressure unit 151.

  The fixing unit 150 includes the fixing belt 102D, the fixing roller 50, and the heating roller 80, and the pressing unit 151 includes the pressing roller 60, the pressing belt 160, and the tension roller 161. The fixing device 6D is a twin belt fixing device. In the present embodiment, the fixing member is the fixing belt 102D.

  The fixing belt 102D is an endless belt-like member that is stretched between the fixing roller 50 and the heating roller 80 to form a loop-shaped movement path. The fixing belt 102D is provided so as to come into contact with the pressure belt 160 at a pressure contact point between the fixing roller 50 and the pressure roller 60, and heats and melts the toner constituting the toner image carried on the recording medium 8 to thereby record the recording medium. 8 is fixed. The fixing belt 102D is driven to rotate in the direction of the arrow 78d by the rotation driving of the fixing roller 50 in the direction of the arrow 78D.

  The fixing belt 102D is an endless belt having a thickness of 270 μm, which has a three-layer structure including a support layer, an elastic layer, and a release layer, and is formed in a cylindrical shape having a diameter of 50 mm.

  The material for forming the support layer is not particularly limited as long as it is excellent in heat resistance and durability, but a heat-resistant synthetic resin can be raised, and among them, polyimide (P1), polyamideimide (PAI) and the like are preferable. . These resins are excellent in strength, heat resistance, price and the like. The thickness of the support layer is not particularly limited, but is preferably 30 to 200 μm.

  The material constituting the elastic layer is not particularly limited as long as it has rubber elasticity, but is preferably superior in heat resistance. Specific examples of such materials include silicone rubber, fluorine rubber, fluorosilicone rubber, and the like. Among these, silicone rubber having particularly excellent rubber elasticity is preferable. The elastic layer preferably has a JIS-A hardness of 1 to 60 degrees. Within this JIS-A hardness range, it is possible to prevent poor toner fixability while preventing a decrease in the strength of the elastic layer and poor adhesion. Specifically, one-component, two-component or three-component or more silicone rubber, LTV type, RTV type or HTV type silicone rubber, condensation type or addition type silicone rubber can be used as the silicone rubber. . Moreover, it is preferable that the thickness of an elastic layer is 30-500 micrometers. If it is this thickness range, heat insulation can be restrained low, maintaining the elastic effect of an elastic layer, and the energy saving effect can be exhibited.

The configuration of the release layer is the same as the configuration of the release layer 102A of the 1A embodiment.
The fixing roller 50 uses a roller-like member formed in a cylindrical shape with a diameter of 30 mm including a cored bar 51, an elastic layer 52, and a surface layer 53.

  As the metal forming the cored bar 51, a metal having high thermal conductivity can be used, and examples thereof include aluminum and iron. Examples of the shape of the core metal 51 include a cylindrical shape and a columnar shape, but a cylindrical shape with a small amount of heat released from the core metal 51 is preferable.

  The material constituting the elastic layer 52 is not particularly limited as long as it has rubber elasticity, but is preferably superior in heat resistance. Specific examples of such materials include silicone rubber, fluorine rubber, fluorosilicone rubber, and the like. Among these, silicone rubber having particularly excellent rubber elasticity is preferable. In order to correct the deviation of the fixing belt 102D, the surface layer 53 may be provided on the elastic layer. This improves the slidability of the surface of the fixing roller 5050 and makes it easy to correct the deviation of the fixing belt 102D.

  The material constituting the surface layer 53 is not particularly limited as long as it is excellent in heat resistance and durability and has high slidability. For example, PFA (a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether), A fluorine-based resin material such as PTFE (polytetrafluoroethylene), fluorine rubber, or the like may be used.

  A heating unit A may be provided inside the fixing roller 50. This prevents a reduction in start-up time from when the power of the image forming apparatus is turned on until image formation is possible, and a decrease in the surface temperature of the fixing roller 50 due to heat transfer to the recording medium during toner image fixing. Because.

  The heating roller 80 is a roller-like member that is rotatably supported and is provided so that tension can be applied to the fixing belt 102D by a pressure unit (not shown). The heating roller 80 rotates following the rotation of the fixing belt 102D in the arrow X direction. As the heating roller 80, a metal roller made of a metal having high thermal conductivity such as aluminum or iron can be used. The metal roller may have a fluororesin layer formed on the surface thereof as necessary.

  The heating roller 80 has a heating means g therein. As a result, the fixing belt 102D is heated. A power source (not shown) is connected to the heating means g, and power for causing the heating means g to generate heat is supplied. A general heating means can be used for the heating means g. In the present embodiment, a halogen lamp is used as the heating means g.

  The pressure belt 160 is stretched by a tension roller 161 and a pressure roller 60 as a belt suspension member. The tension roller 161 and the pressure roller 60 are rotatably supported and supported between left and right side plates (not shown) of the fixing device 6D.

  The pressure belt 160 rotates following the fixing belt 102D. Here, by adopting a configuration in which the fixing nip most downstream portion is conveyed with the fixing belt 102D and the pressure belt 160 sandwiched by a pair of rollers, the belt can be prevented from slipping. The most downstream portion of the fixing nip is a portion where the pressure distribution (recording material conveyance direction) at the fixing nip is maximized.

  As the pressure roller 60, a roller-shaped member having a diameter of 30 mm including a cored bar 61, an elastic layer 62, and a surface layer 63 is used. As materials for forming the cored bar 61, the elastic layer 62, and the surface layer 63, the same materials as those for the pressure roller 60 of the first embodiment A can be used. The shape of the cored bar 61 is the same as that of the fixing roller 50.

  A heating unit h is provided inside the pressure roller 60. This is because the start-up time from when the image forming apparatus is turned on until the image can be formed is shortened, and the surface temperature of the pressure roller 60 is suddenly lowered due to the transfer of heat to the recording medium when fixing the toner image. It is for preventing.

  The tension roller 161 has an iron alloy cored bar 162 having an outer diameter of 30 mm and an inner diameter of 26 mm. A silicone sponge layer 163 is formed on the iron roller core 163 in order to reduce the thermal conductivity and reduce the heat conduction from the pressure belt 160. Provided. Here, in order to form a fixing nip as an image heating nip between the fixing belt 102D and the pressure belt 160, the pressure roller 60 is pressed toward the fixing roller 50 with a predetermined pressure. Yes.

  In order to obtain a wide fixing nip without increasing the size of the apparatus, a fixing pad 164 as a first pressure pad that presses the fixing belt 102D toward the pressure belt 160, and the pressure belt 160 as the fixing belt 102D. A pressure pad 165 is provided as a second pressure pad that pressurizes the pressure. The fixing pad 164 and the pressure pad 165 are supported between left and right side plates (not shown) of the apparatus. The pressure pad 165 is pressed toward the fixing pad 164 with a predetermined pressure in the direction of the arrow 165a by a pressure mechanism (not shown).

  The fixing pad 164 as the first pressure pad and the pressure pad 165 as the second pressure pad are made of PPS (polyphenylene sulfide resin).

  When a nip is formed with a pad that is not a rotating body, the inner peripheral surface of the belt is rubbed against the pad. If the friction coefficient between the belt inner peripheral surface and the pad is large, the sliding resistance increases, resulting in problems such as image misalignment, gear breakage, and drive motor power consumption increase. This problem is particularly noticeable in the upper and lower belt systems. Therefore, the fixing pad 164 and the pressure pad 165 are provided with a low friction sheet in which the pad contacts the belt. As a result, pad scraping due to rubbing against the belt can be prevented and sliding resistance can be reduced, so that good belt running performance and belt durability can be obtained.

  FIG. 7 is a block diagram regarding control of members related to heating of the fixing device 6D and driving of the fixing roller 50. Electric power is supplied from the power supply circuit 128 to the heating means g of the heating roller 80 to heat the heating roller 80. The rotating fixing belt 102 </ b> D is heated by the heating roller 80. The surface temperature of the fixing belt 102D is detected by the thermistor G which is a temperature detecting element. A signal relating to the temperature of the fixing belt 102 </ b> D detected by the thermistor G is input to the control circuit 129. The control circuit 129 controls the power supplied from the power supply circuit 128 to the heating means g so that the temperature information input from the thermistor G is maintained at a predetermined fixing temperature, so that the temperature of the fixing belt 102D becomes a predetermined fixing temperature. Adjust.

  In a state where the fixing belt 102D rises to a predetermined fixing temperature and is temperature-controlled, the recording medium 8 having an unfixed toner image is conveyed to the fixing nip between the fixing belt 102D and the pressure belt 160. The recording medium 8 is introduced with the surface carrying the unfixed toner image facing the fixing belt 102D. Then, the unfixed toner image of the recording medium 8 is nipped and conveyed while being in close contact with the outer peripheral surface of the fixing belt 102D, whereby heat is applied from the fixing belt 102D to the recording medium 8, and the toner image is received under pressure. Is fixed on the surface of the recording medium 8.

  The thermistor G is provided so as to be close to the fixing belt 102D at a position facing the heating roller 80 via the fixing belt 102D, and detects the temperature of the fixing belt 102D. The thermistor H is provided close to the pressure belt 160 at a position facing the pressure roller 60 via the pressure belt 160, and detects the temperature of the pressure belt 160. Detection results by the thermistors G and H are input to the CPU 127.

  The CPU 127 determines whether or not the temperature of the thermistor G is within the set range from the detection result of the thermistor G. When the temperature of the fixing belt 102D is lower than the set range, a control signal is sent to the power supply circuit 128 connected to the heating unit g, and electric power is supplied to the heating unit g to promote heat generation. When the temperature of the fixing belt 102D is higher than the set range, the presence / absence of power supply to the heating unit g is confirmed. When power supply is continued, a control signal for stopping power supply is sent to the power supply circuit 128.

  The CPU 127 determines whether or not the temperature of the thermistor H is within the set range from the detection result of the thermistor H. When the temperature of the pressure belt 160 is lower than the set range, a control signal is sent to the power supply circuit 128 connected to the heating unit h to supply power to the heating unit h to promote heat generation. When the temperature of the fixing belt 102D is higher than the set range, the presence / absence of power supply to the heating unit h is confirmed. When power supply is continued, a control signal for stopping power supply is sent to the power supply circuit 128.

  The fixing belt 102D is provided at a position facing the heating roller 80 via the fixing belt 102D and downstream of the thermistor G in the rotation direction of the fixing belt 102D so as to be close to the fixing belt 102D, and detects an abnormal temperature increase of the fixing belt 102D. A thermostat 130 is disposed. The detection result by the thermostat 130 is input to the CPU 127. The CPU 127 stops the power supply from the power supply circuit 128 connected to the heating means g according to the detection result of the thermostat 130.

  The fixing mechanism including the fixing roller 50, the heating roller 80, the fixing belt 102D, and the pressure roller 60 is controlled by the CPU 127 that controls the entire operation of the image forming apparatus.

  When the CPU 127 receives an input of an image formation instruction, the CPU 127 sends a control signal to the power supply circuit 128 that supplies power to the heating units g and h provided inside the heating roller 80 and the pressure roller 60. The image forming instruction is input from an operation panel (not shown) provided on the upper surface in the vertical direction of the image forming apparatus or an external device such as a computer connected to the image forming apparatus. The power supply that has received the control signal supplies power to activate the heating means g and h.

  The heating means g and h heat the fixing roller 50, the heating roller 80, the pressure roller 60, and the surface of the fixing belt 102D so as to have respective set temperatures. When a temperature detection sensor provided in the vicinity of the fixing roller 50 and the pressure roller 60 detects that the set temperature has been reached and the detection result is input to the CPU 127, the CPU 127 causes the fixing roller 50 to be moved via the control circuit 129. A control signal is sent to the fixing roller driving motor 131 that is driven to rotate, and the pressure roller 60 is driven to rotate in the direction of the arrow. Accordingly, the fixing belt 102D, the fixing roller 50, and the heating roller 80 are driven to rotate.

  In the present embodiment, a halogen lamp is used as the heating means g inside the heating roller 80 of the fixing unit 150, but an external heating device may be provided on the outer periphery of the heating roller 80 instead. Moreover, you may use the induction heating apparatus using induction heating, and may comprise combining these suitably.

2. Image Forming Apparatus FIG. 8 is a schematic diagram showing the configuration of the image forming apparatus 1 including the fixing device 6A of the present invention. As shown in FIG. 8, the image forming apparatus 1 includes an image forming unit 2, an intermediate transfer unit 3, a secondary transfer unit 4, a fixing device 6, and a recording medium supply unit 5.

  The image forming means 2 includes image forming units 10y, 10m, 10c, and 10b, which form an electrostatic latent image corresponding to a digital signal of each hue (hereinafter referred to as “image information”), and The electrostatic latent image is developed to form an image formed by each color toner. That is, the image forming unit 10y forms a toner image corresponding to yellow image information, the image forming unit 10m forms toner corresponding to magenta image information, and the image forming unit 10c converts cyan image information. A corresponding toner image is formed, and the image forming unit 10b forms a toner image corresponding to black image information.

  The image forming units 10y, 10m, 10c, and 10b use a yellow developer, a magenta developer, a cyan developer, or a black developer, respectively, and image information input to the image forming unit 2 A pixel signal corresponding to a yellow color component image, a pixel signal corresponding to a magenta color component image, a pixel signal corresponding to a cyan color component image, and a pixel signal corresponding to a black color component image are respectively input. Accordingly, hereinafter, the image forming unit 10y corresponding to the yellow color is shown as a representative example, and the description of the other is omitted. When the image forming unit 10 or the like corresponding to each color is indicated individually, it is represented by adding alphabetic suffixes: y (yellow color), m (magenta color), c (cyan color), b (black). .

  The image forming units 10y, 10m, 10c, and 10b are arranged in a line in this order from the upstream side to the downstream side in the moving direction (sub operation direction) of the intermediate transfer belt 21 that is an intermediate transfer medium, that is, the direction of the arrow 27. Arranged.

  FIG. 9 is a schematic diagram showing the configuration of the image forming unit 10y. As shown in FIG. 9, the image forming unit 10y includes a photosensitive drum 11y on which a yellow toner image is formed, a charging roller 12y that uniformly charges the surface of the photosensitive drum 11y, and a charged photosensitive drum. An optical scanning unit 13 that forms an electrostatic latent image by exposing light corresponding to image information to the surface of the photosensitive drum 11y, and a toner image by attaching toner to the electrostatic latent image formed on the surface of the photosensitive drum 11y. And a drum cleaner 15y that removes and collects toner remaining on the surface of the photosensitive drum 11y without being intermediately transferred to the intermediate transfer belt 21.

  The photosensitive drum 11y is a latent image carrier on which an electrostatic latent image is formed on the surface thereof when exposed to light according to image information, and is provided rotatably. The photosensitive drum 11y is supported by a driving unit (not shown) so as to be rotatable around an axis, and includes a cylindrical, columnar, or thin film sheet (preferably cylindrical) conductive substrate (not shown) and the surface of the conductive substrate. And a photosensitive layer formed thereon.

  As the photoreceptor drum 11y, those commonly used in this field can be used. For example, the photoreceptor drum 11y includes an aluminum base tube that is a conductive substrate and an organic photosensitive layer that is a photosensitive layer formed on the surface of the aluminum base tube. Examples thereof include a photosensitive drum 11y having a diameter of 30 mm connected to a GND (Ground) potential.

  The organic photosensitive layer may be formed by laminating a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material, and the charge generation material and the charge transport material are combined into one layer. May be included. The layer thickness of the organic photosensitive layer is not particularly limited, but is, for example, 20 μm. An underlayer may be provided between the organic photosensitive layer and the conductive substrate. Further, a protective layer may be provided on the surface of the organic photosensitive layer.

  The photosensitive drum 11y is rotationally driven in a counterclockwise direction toward the paper surface of FIG. 8, for example, at a peripheral speed of 173 mm / s. The driving means for the photosensitive drum 11y is controlled by a control means (not shown), thereby controlling the rotational speed of the photosensitive drum 11y.

  The charging roller 12y is a charging unit that charges the surface of the photosensitive drum 11y to a potential having a predetermined polarity. The charging means is not limited to the charging roller 12y, and instead of the charging roller 12y, a brush-type charger, a charger-type charger, or a corona charger such as a scorotron can be used.

  The optical scanning unit 13 irradiates the charged surface of the photosensitive drum 11y with a laser beam 13y corresponding to yellow image information, and electrostatically corresponds to the yellow image information on the surface of the photosensitive drum 11y. It is a latent image forming means for forming a latent image. A semiconductor laser element or the like is used as the laser light source.

  The developing device 14y is provided facing the photosensitive drum 11y, and supports the yellow developer 16y including yellow toner and a carrier on the surface of the developing sleeve 18y and transports the surface to the photosensitive drum 11y. Development means for developing and developing the electrostatic latent image formed on the substrate. As the developing device 14y, a one-component developer that does not include a carrier can be used.

  The developing sleeve 18y is rotationally driven in the same direction as the rotational driving direction of the photosensitive drum 11y in the developing nip portion adjacent to the photosensitive drum 11y. Therefore, the rotational drive direction around the axis is the opposite direction. In the present embodiment, the peripheral speed of the developing sleeve 18y is 260 mm / s, which is 1.5 times that of the photosensitive drum 11y, for example.

  The drum cleaner 15y removes and collects the yellow toner remaining on the surface of the photosensitive drum 11y after the yellow toner image on the surface of the photosensitive drum 11y is intermediately transferred to the intermediate transfer belt 21.

(Developer)
Hereinafter, the components of the developers 16y, 16m, 16c, and 16b used in the image forming apparatus 1 of the present embodiment will be described in detail.

  The toner contained in the developer contains a binder resin, a colorant, and a release agent. As the binder resin, those commonly used in this field can be used. For example, polystyrene, styrene-substituted homopolymer, styrene copolymer, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane Etc. Binder resin can be used individually by 1 type, or can use 2 or more types together.

  Among these binder resins, for color toners, a binder resin having a softening point of 100 to 150 ° C. and a glass transition point of 50 to 80 ° C. is preferable from the viewpoint of storage stability and durability. Polyester having a glass transition point is particularly preferred. Polyester exhibits high transparency in a softened or molten state. When the binder resin is polyester, when a multicolor toner image in which toner images of yellow, magenta, cyan and black are superimposed on each other is fixed on the recording medium 8, the polyester itself becomes transparent. Is obtained.

  As the colorant, pigments and dyes for toners conventionally used in electrophotographic image forming techniques can be used. Examples of the pigment include azo pigments, benzimidazolone pigments, quinacridone pigments, phthalocyanine pigments, isoindolinone pigments, isoindoline pigments, dioxazine pigments, anthraquinone pigments, perylene pigments, and perinone pigments. , Organic pigments such as thioindigo pigments, quinophthalone pigments, metal complex pigments, inorganic pigments such as carbon black, titanium oxide, molybdenum red, chrome yellow, titanium yellow, chromium oxide, Berlin blue, metals such as aluminum powder Examples include powder. A pigment can be used individually by 1 type or can use 2 or more types together.

  As the release agent, for example, wax can be used. As the wax, those commonly used in this field can be used, and examples thereof include polyethylene wax, polypropylene wax, and paraffin wax. The toner contains one or more general toner additives such as a charge control agent, a fluidity improver, a fixing accelerator, and a conductive agent in addition to the binder resin, the colorant, and the release agent. it can.

  The toner is obtained by uniformly dispersing a coloring agent, a release agent, a binder resin monomer, and the like by a pulverization method in which a colorant, a release agent, and the like are melt-kneaded and pulverized with the binder resin. It can be produced according to a known method such as a suspension polymerization method in which polymerization is performed, a binder resin particle, a colorant, a release agent, or the like is aggregated with an aggregating agent, and fine particles of the obtained aggregate are heated.

  The volume average particle diameter of the toner is not particularly limited, but is preferably 2 to 7 μm. Further, when the volume average particle diameter of the toner is appropriately small as described above, the coverage with respect to the recording medium is increased, so that high image quality and low toner consumption can be achieved with a low adhesion amount.

  When the volume average particle diameter of the toner is less than 2 μm, the fluidity of the toner is lowered, and during the developing operation, the toner supply, agitation and charging become insufficient, the toner amount is insufficient, and the reverse polarity toner is increased. This may occur and a high quality image may not be obtained. On the other hand, when the volume average particle diameter exceeds 7 μm, the toner particles having a large particle diameter that is difficult to be softened to the central portion increase, so that the fixability of the image to the recording medium 8 is lowered and the color of the image is deteriorated. In particular, in the case of fixing to OHP, the image becomes dark.

Each color toner used in the present embodiment has the same configuration as shown below except for the colorant. This toner is, for example, a toner having a glass transition point of 60 ° C., a softening point of 120 ° C., and a volume average particle size of 6 μm, and is a negatively chargeable insulating nonmagnetic toner. A toner amount of 5 g / m ² is required to obtain an image density with a reflection density measurement value of 1.4 by X-Rite 310 using this toner. This toner contains polyester having a glass transition point of 60 ° C. and a softening point of 120 ° C. as a binder resin, a low molecular weight polyethylene wax having a glass transition point of 50 ° C. and a softening point of 70 ° C. as a release agent, and pigments of various colors as colorants. The wax content is 7% by weight of the total amount of the toner, the pigment content is 12% by weight of the total amount of the toner, and the balance is polyester of the binder resin.

  The low molecular weight polyethylene wax contained in the toner is a wax having a glass transition point and a softening point lower than that of the polyester of the binder resin. If such a wax is used, the adhesive force between the toners and the adhesive force between the toner and the intermediate transfer belt 21 or the recording medium are increased even at a temperature lower than the glass transition point of the binder resin. When the fixing solution is applied, it is possible to suppress the occurrence of toner flow and aggregation due to the fixing solution. Further, when the wax in the toner is softened, the fixer easily penetrates into the toner from the location where the wax exists. Therefore, the entire toner softens or swells in a short time when the fixing solution is applied, and sufficient fixing strength is obtained when transferring to a recording medium, and color development due to toner image superposition is also sufficient.

  Developers 16y, 16m, 16c, and 16b may contain a carrier in addition to the toner. As the carrier, magnetic particles can be used. Specific examples of the particles having magnetism include metals such as iron, ferrite, and magnetite, and alloys of these metals with metals such as aluminum or lead. Among these, ferrite is preferable.

  Alternatively, a resin-coated carrier in which magnetic particles are coated with a resin, or a resin-dispersed carrier in which magnetic particles are dispersed in a resin may be used as the carrier. The resin that coats the magnetic particles is not particularly limited, and examples thereof include olefin resins, styrene resins, styrene / acrylic resins, silicon resins, ester resins, and fluorine-containing polymer resins. . Moreover, although it does not restrict | limit especially as resin used for a resin dispersion type carrier, For example, a styrene acrylic resin, a polyester resin, a fluorine resin, a phenol resin, etc. are mentioned.

The shape of the carrier is preferably a spherical shape or a flat shape. The volume average particle diameter of the carrier is not particularly limited, but is preferably 30 μm or more and 50 μm or less in consideration of high image quality. Furthermore, the resistivity of the carrier is preferably 10 ⁸ Ω · cm or more, more preferably 10 ¹² Ω · cm or more. The carrier resistivity is determined by placing the carrier in a container having a cross-sectional area of 0.50 cm 2 and tapping it, then applying a load of 1 kg / cm 2 to the particles packed in the container, and applying 1000 V / cm between the load and the bottom electrode. This is a value obtained by reading a current value when a voltage generating an electric field of cm is applied. If the resistivity is low, when a bias voltage is applied to the developing sleeve 18, charges are injected into the carrier, and carrier particles easily adhere to the photosensitive drum 11. Further, breakdown of the bias voltage is likely to occur.

  The magnetization strength (maximum magnetization) of the carrier is preferably 10 emu / g to 60 emu / g, more preferably 15 emu / g to 40 emu / g. Although the magnetization strength depends on the magnetic flux density of the developing sleeve 18, under the general magnetic flux density conditions of the developing sleeve 18, if the magnetic strength is less than 10 emu / g, the magnetic binding force does not work, causing carrier scattering. There is a risk of becoming. On the other hand, if the magnetization strength exceeds 60 emu / g, it is difficult to maintain a non-contact state with the photosensitive drum 11 which is a latent image carrier in non-contact development in which carrier spikes are too high. Further, in the contact development, there is a risk that a sweep is likely to appear in the toner image.

  The usage ratio of the toner 101 and the carrier in the developers 16y, 16m, 16c, and 16b is not particularly limited, and may be appropriately selected according to the types of the toner 101 and the carrier.

  According to the image forming unit 10y, for example, 1200 V is applied to the charging roller 12y by a power source (not shown) while rotating the photosensitive drum 11y about its axis, and the surface of the photosensitive drum 11y is set to 600 V, for example, by discharging. Charge. Next, the surface of the charged photosensitive drum 11y is irradiated with laser light 13y corresponding to yellow image information from the optical scanning unit 13, and electrostatic at an exposure potential of −70 V corresponding to yellow image information. A latent image is formed.

  Next, the surface of the photosensitive drum 11y and the yellow developer carried on the surface of the developing sleeve 18y are brought close to each other. A DC voltage of −450 V is applied as a developing potential to the developing sleeve 18y, and yellow toner adheres to the electrostatic latent image due to a potential difference between the developing sleeve 18y and the photosensitive drum 11y, and the surface of the photosensitive drum 11y. Thus, a yellow toner image is formed. As will be described later, this yellow toner image is intermediately transferred to the intermediate transfer belt 21 that is pressed against the surface of the photosensitive drum 11 y and driven in the direction of the arrow 28. The yellow toner 101 remaining on the surface of the photosensitive drum 11y is removed and collected by the drum cleaner 15y. Thereafter, the yellow toner image forming operation is repeatedly executed in the same manner.

  Returning to FIG. 8, the intermediate transfer unit 3 includes an intermediate transfer belt 21, intermediate transfer rollers 24 y, 24 m, 24 c and 24 b, support rollers 25, 26 and 29, and a belt cleaner 27. The intermediate transfer belt 21 is an endless belt-like image carrier that is stretched between support rollers 25, 26, and 29 to form a loop-like movement path, and is substantially the same as the photosensitive drums 11y, 11m, 11c, and 11b. At the same peripheral speed, the image bearing surface facing the photosensitive drums 11y, 11m, 11c, and 11b is rotationally driven so as to move from the photosensitive drum 11y toward the photosensitive drum 11b. .

  For the intermediate transfer belt 21, for example, a polyimide film having a thickness of 100 μm can be used. The material of the intermediate transfer belt 21 is not limited to polyimide, and films composed of synthetic resins such as polycarbonate, polyamide, polyester, and polypropylene, and various rubbers can be used. In the film made of synthetic resin or various rubbers, a conductive material such as furnace black, thermal black, channel black, and graphite carbon is blended in order to adjust the electric resistance value of the intermediate transfer belt 21. Further, the intermediate transfer belt 21 may be provided with a coating layer made of a fluororesin composition or fluororubber having a low adhesion to toner. Examples of the constituent material of the covering layer include PTFE (polytetrafluoroethylene) and PFA (a copolymer of PTFE and perfluoroalkyl vinyl ether). A conductive material may be blended in the coating layer.

  The image carrying surface of the intermediate transfer belt 21 is pressed against the photosensitive drums 11y, 11m, 11c, and 11b in this order from the upstream side in the rotational driving direction of the intermediate transfer belt 21. The positions where the intermediate transfer belt 21 is pressed against the photosensitive drums 11y, 11m, 11c, and 11b are the intermediate transfer positions of the respective color toner images.

  The intermediate transfer rollers 22y, 22m, 22c, and 22b are provided to face the photosensitive drums 11y, 11m, 11c, and 11b with the intermediate transfer belt 21 interposed therebetween, and are opposite to the image carrying surface of the intermediate transfer belt 21. It is a roller-like member provided in pressure contact with the surface and capable of rotating around its axis by a driving means (not shown).

  For the intermediate transfer rollers 22y, 22m, 22c, and 22b, for example, a roller-shaped member including a metal shaft body and a conductive layer that covers the surface of the metal shaft body is used. The metal shaft body is formed of a metal such as stainless steel, for example. The diameter of the metal shaft is not particularly limited, but is preferably 8 mm to 10 mm. The conductive layer is formed of a conductive elastic body or the like. As the conductive elastic body, those commonly used in this field can be used, and examples thereof include ethylene-propylene rubber (hereinafter referred to as EPDM), foamed EPDM, foamed urethane and the like containing a conductive agent such as carbon black. A high voltage is uniformly applied to the intermediate transfer belt 21 by the conductive layer.

  The intermediate transfer rollers 22y, 22m, 22c, and 22b are opposite to the charging polarity of the toner in order to transfer the toner images formed on the surfaces of the photosensitive drums 11y, 11m, 11c, and 11b onto the intermediate transfer belt 21. A polar intermediate transfer bias is applied by constant voltage control. As a result, yellow, magenta, cyan, and black toner images formed on the photoconductive drums 11y, 11m, 11c, and 11b are sequentially superimposed and transferred onto the image carrying surface of the intermediate transfer belt 21, and a multicolor toner image is transferred. Is formed. However, when image information of only a part of yellow, magenta, cyan, and black colors is input, the image forming unit 10y, 10m, 10c, 10b corresponds to the color of the input image information. A toner image is formed only in the unit 10.

  Of the support rollers 23, 24, and 25, the support rollers 23 and 24 are provided so as to be rotatable around an axis by a driving unit (not shown), and the intermediate transfer belt 21 is stretched and rotated in the direction of the arrow 28. . For the support rollers 23, 24, 25, for example, an aluminum cylinder (pipe-shaped roller) having a diameter of 30 mm and a wall thickness of 1 mm is used. Among these, the support roller 24 is pressed against a later-described secondary transfer roller 28 via the intermediate transfer belt 21 to form a secondary transfer nip portion, and is electrically grounded. The support roller 24 has a function of stretching the intermediate transfer belt 21 and a function of secondarily transferring the toner image on the intermediate transfer belt 21 to the recording medium 8.

  The belt cleaner 26 is a member that removes toner remaining on the image carrying surface after the toner image on the image carrying surface of the intermediate transfer belt 21 is transferred to the recording medium 8 by the secondary transfer unit 4 described later. It is provided so as to face the support roller 28 with the transfer belt 21 in between.

  According to the intermediate transfer means 4, the toner images formed on the photoconductive drums 11y, 11m, 11c, and 11b have a high voltage having a polarity opposite to the charged polarity of the toner on the intermediate transfer rollers 22y, 22m, 22c, and 22b. By being applied uniformly, the toner image is formed by being superimposed and transferred onto a predetermined position on the image carrying surface of the intermediate transfer belt 21 to form an intermediate image. As will be described later, this toner image is secondarily transferred to the recording medium 8 at the secondary transfer nip portion. The toner and paper dust remaining on the image carrying surface of the intermediate transfer belt 21 after the secondary transfer are removed by the belt cleaner 27, and the toner image is transferred again to the image carrying surface.

  The secondary transfer unit 4 includes a support roller 24 and a secondary transfer roller 28. The secondary transfer roller 28 is a roller-like member that is in pressure contact with the support roller 24 via the intermediate transfer belt 21 and is rotatably driven in the axial direction. The secondary transfer roller 28 includes, for example, a metal shaft body and a conductive layer coated on the surface of the metal shaft body. The metal shaft body is formed of a metal such as stainless steel, for example. The conductive layer is formed of a conductive elastic body or the like. As the conductive elastic body, those commonly used in this field can be used, and examples thereof include EPDM, foamed EPDM, foamed urethane and the like containing a conductive material such as carbon black. A power supply (not shown) is connected to the secondary transfer roller 31, and a high voltage having a polarity opposite to the charging polarity of the toner particles is uniformly applied. A pressure contact portion between the support roller 24, the intermediate transfer belt 21, and the secondary transfer roller 28 is a secondary transfer nip portion.

  According to the secondary transfer unit 4, two recording media 8 fed from a recording medium supply unit 5 described later are synchronized with the toner image on the intermediate transfer belt 21 being conveyed to the secondary transfer nip portion. It is conveyed to the next transfer nip. Then, the toner image and the recording medium 8 are overlapped at the secondary transfer nip portion, and a high voltage having a polarity opposite to the charging polarity of the toner 101 is uniformly applied to the secondary transfer roller 28 to form the toner. The image is secondarily transferred to the recording medium 8. Then, the recording medium 8 carrying the toner image is conveyed to a fixing device 6A which is a fixing unit.

  The intermediate transfer means 3 and the secondary transfer means 4 correspond to transfer means for transferring the toner image on the surface of the photosensitive drum 11 as a latent image carrier to the recording medium 8.

  As described above, the image forming apparatus 1 includes the fixing device 6A of the present invention. As a result, the flexibility of the release layer 102A can be increased to such an extent that the toner can be sufficiently fixed to the recording medium 8, and even when a toner image is formed by laminating toner as in a color image, Since the toner image can be fixed following the unevenness of the recording medium 8, a glossy image can be formed.

  EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[Surface roughness Ra]
The surface roughness Ra of the release layer was determined by directly measuring the release layer using Surfcoder SE3500 (Kosaka Laboratory Ltd.) and taking an average value of three times.

[Measuring method of melt flow index]
A full automatic melt flow index tester (manufactured by Yasuda Seiki Seisakusyo) was used to measure the melt flow index of the uncrosslinked fluororesin. A molten sample in a cylinder at a constant temperature was extruded from a die by a piston under a constant load, and the mass and volume of the molten sample extruded within 10 minutes were measured, and an average value of three times was calculated.

[Weight average molecular weight Mw of uncrosslinked fluororesin]
Using a GPC apparatus (trade name: HLC-8220 GPC, manufactured by Tosoh Corporation), at a temperature of 40 ° C., a 0.25 wt% tetrahydrofuran (hereinafter referred to as THF) solution of the sample was used as the sample solution, and the sample solution was injected. The molecular weight distribution curve was determined with an amount of 200 μL. The molecular weight at the peak of the obtained molecular weight distribution curve was determined as the peak top molecular weight. Moreover, the weight average molecular weight Mw was calculated | required from the obtained molecular weight distribution curve. The molecular weight calibration curve was prepared using standard polystyrene.

[Thicknesses of release layer, elastic layer and support layer of fixing belt]
A section of the fixing belt is embedded in an epoxy resin, etc., surfaced by cutting with a microtome, and an enlarged photograph is taken between 100 times and 2000 times with a scanning electron microscope (SEM). The thicknesses of the mold layer, elastic layer and support layer were measured.

[Thickness of release layer, elastic layer and support layer of fixing roller]
The elastic layer of the fixing roller is cut out as a section including a release layer, embedded in an epoxy resin, etc., surfaced by cutting with a macrotome, and then observed with an SEM to release the release layer. The thickness of was measured. The thickness of the support layer was determined by measuring with a commercially available micrometer before manufacturing the fixing roller. For the elastic layer, the diameter of the fixing roller after coating the release layer was measured using a commercially available micrometer, and the value of twice the thickness of the release layer from the diameter of the fixing roller and the thickness of the support layer were measured. The value obtained by subtracting was divided by 2.

(Fixing belt production)
Example 1
Cross-linked fluororesin (trade name: XF1A, manufactured by Hitachi Cable Finetech Co., Ltd.) and uncrosslinked fluororesin (Mw = 930,000, melt flow index (hereinafter referred to as “MF”) = 5 g / 10 min, melting point 290 ° C.) Were blended in a ratio of crosslinked fluororesin: uncrosslinked fluororesin = 30: 70 and mixed with a simple kneader to obtain a coating agent. This coating agent is a fluororesin dispersion in which the solid content concentration of the crosslinked fluororesin and the uncrosslinked fluororesin is adjusted to 40%. Toluene was used as a solvent for dispersing these fluororesins. Moreover, the shaping | molding die which mirror-polished the outer peripheral surface of the stainless steel (SUS304) pipe of internal diameter 60mm and thickness 3mm was prepared.

  Subsequently, a polyimide varnish (trade name: RC-5057, manufactured by I.S.T.) was applied to the outer surface as a support layer, and baked at 250 ° C. for 30 minutes after drying. The thickness of the support layer after firing was 80 μm.

  Next, after the fired mold was cooled to room temperature, silicone rubber (trade name: KE-1241, manufactured by Shin-Etsu Silicon Co., Ltd.) was applied as an elastic layer, and fired at 250 ° C. for 30 minutes. The thickness of the elastic layer after firing was 200 μm, and the JIS hardness was A10 degrees.

  Finally, the coating agent was applied and baked at 380 ° C. for 15 minutes. The thickness of the release layer after firing was 20 μm. When the thickness of the release layer was 3 μm or more as in this example, the thickness was adjusted to 20 μm by repeatedly coating the coating agent.

  After cooling the mold to room temperature, the produced annular product was taken from the mold and the fixing belt of Example 1 was obtained. No wrinkles were found on the surface of the obtained fixing belt.

(Example 2)
Other than using an uncrosslinked fluororesin (Mw = 300,000) having an MF of 25 g / 10 min and a melting point of 250 ° C., instead of the uncrosslinked fluororesin having an MF of 5 g / 10 min and a melting point of 290 ° C. Obtained a fixing belt of Example 2 in the same manner as in Example 1. No wrinkles were found on the surface of the obtained fixing belt.

(Example 3)
An uncrosslinked fluororesin (Mw = 600,000) having an MF of 15 g / 10 min and a melting point of 270 ° C. was used instead of the uncrosslinked fluororesin having an MF of 5 g / 10 min and a melting point of 290 ° C. A fixing belt of Example 3 was obtained in the same manner as in Example 1 except that the number of times was reduced and the thickness of the release layer was reduced to 5 μm. No wrinkles were found on the surface of the obtained fixing belt.

Example 4
Other than using an uncrosslinked fluororesin (Mw = 600,000) having an MF of 15 g / 10 min and a melting point of 270 ° C. instead of the uncrosslinked fluororesin having an MF of 5 g / 10 min and a melting point of 290 ° C. Obtained a fixing belt of Example 4 in the same manner as in Example 1. No wrinkles were found on the surface of the obtained fixing belt.

(Example 5)
An uncrosslinked fluororesin (Mw = 600,000) having an MF of 15 g / 10 min and a melting point of 270 ° C. was used instead of the uncrosslinked fluororesin having an MF of 5 g / 10 min and a melting point of 290 ° C. The fixing belt of Example 5 was obtained in the same manner as in Example 1 except that the number of times was increased and the thickness of the release layer was increased to 30 μm. No wrinkles were found on the surface of the obtained fixing belt.

(Example 6)
Instead of an uncrosslinked fluororesin having an MF of 5 g / 10 min and a melting point of 290 ° C., an uncrosslinked fluororesin (Mw = 600,000) having an MF of 15 g / 10 min and a melting point of 270 ° C. is used. A fixing belt of Example 6 was obtained in the same manner as in Example 1 except that the resin and the uncrosslinked fluororesin were blended at a ratio of 40:60 and mixed with a simple kneader. No wrinkles were found on the surface of the obtained fixing belt.

(Example 7)
Example 3 except that the cross-linked fluororesin and the non-cross-linked fluororesin were mixed at a ratio of 50:50 and mixed with a simple kneader, and the number of coatings was increased to increase the thickness of the release layer to 20 μm. Similarly, a fixing belt of Example 7 was obtained. No wrinkles were found on the surface of the obtained fixing belt.

(Example 8)
Example 3 except that the cross-linked fluororesin and the non-cross-linked fluororesin were blended at a ratio of 60:40 and mixed with a simple kneader, and the number of coatings was increased to increase the thickness of the release layer to 20 μm. Similarly, a fixing belt of Example 8 was obtained. No wrinkles were found on the surface of the obtained fixing belt.

Example 9
Example 3 except that the cross-linked fluororesin and the non-cross-linked fluororesin were mixed at a ratio of 70:30 and mixed with a simple kneader, and the number of coatings was increased to increase the thickness of the release layer to 20 μm. Similarly, a fixing belt of Example 9 was obtained. No wrinkles were found on the surface of the obtained fixing belt.

(Example 10)
The same as in Example 3 except that the cross-linked fluororesin and the non-cross-linked fluororesin were blended in a ratio of 50:50 and mixed with a simple kneader, and the number of coatings was reduced to reduce the thickness of the release layer to 3 μm. Thus, a fixing belt of Example 10 was obtained. No wrinkles were found on the surface of the obtained fixing belt.

(Example 11)
The same as in Example 3 except that the cross-linked fluororesin and the non-cross-linked fluororesin were mixed at a ratio of 50:50 and mixed with a simple kneader, and the number of coatings was increased to increase the thickness of the release layer to 35 μm. Thus, a fixing belt of Example 11 was obtained. No wrinkles were found on the surface of the obtained fixing belt.

Example 12
A fixing belt of Example 12 was obtained in the same manner as in Example 3 except that the thickness of the release layer was increased to 20 μm and a mold having a rough surface was used so that the surface roughness of the release layer was increased. . No wrinkles were found on the surface of the obtained fixing belt.

(Example 13)
Instead of an uncrosslinked fluororesin having an MF of 5 g / 10 min and a melting point of 290 ° C., an uncrosslinked fluororesin (Mw = 650,000) having an MF of 15 g / 10 min and a melting point of 300 ° C. is used. A fixing belt of Example 13 was obtained in the same manner as in Example 1 except that the resin and the uncrosslinked fluororesin were mixed at a ratio of 50:50 and mixed with a simple kneader. No wrinkles were found on the surface of the obtained fixing belt.

(Example 14)
The MF was 15 g / 10 min, the melting point was 270 ° C., but the uncrosslinked fluororesin of a different type from the uncrosslinked fluororesin used in Example 9 was used. A fixing belt was obtained. No wrinkles were found on the surface of the obtained fixing belt.

(Comparative Example 1)
The same as in Example 3 except that the cross-linked fluororesin and the non-cross-linked fluororesin were blended at a ratio of 20:80 and mixed with a simple kneader, and the number of coatings was increased to increase the thickness of the release layer to 20 μm. Thus, a fixing belt of Comparative Example 1 was obtained. No wrinkles were found on the surface of the obtained fixing belt.

(Comparative Example 2)
The same as in Example 3 except that the crosslinked fluororesin and the uncrosslinked fluororesin were mixed at a ratio of 80:20 and mixed with a simple kneader, and the number of coatings was increased to increase the thickness of the release layer to 20 μm. Thus, a fixing belt of Comparative Example 2 was obtained. No wrinkles were found on the surface of the obtained fixing belt.

(Comparative Example 3)
Instead of an uncrosslinked fluororesin having an MF of 5 g / 10 min and a melting point of 290 ° C., an uncrosslinked fluororesin (Mw = 1 million) having an MF of 3 g / 10 min and a melting point of 245 ° C. is used. A fixing belt of Comparative Example 3 was obtained in the same manner as in Example 1 except that the resin and the uncrosslinked fluororesin were blended at a ratio of 50:50 and mixed with a simple kneader. No wrinkles were found on the surface of the obtained fixing belt.

(Comparative Example 4)
Instead of an uncrosslinked fluororesin having an MF of 5 g / 10 min and a melting point of 290 ° C., an uncrosslinked fluororesin (Mw = 550,000) having an MF of 15 g / 10 min and a melting point of 245 ° C. is used. A fixing belt of Comparative Example 4 was obtained in the same manner as in Example 1 except that the resin and the uncrosslinked fluororesin were mixed at a ratio of 50:50 and mixed with a simple kneader. No wrinkles were found on the surface of the obtained fixing belt.

(Comparative Example 5)
Instead of an uncrosslinked fluororesin having an MF of 5 g / 10 min and a melting point of 290 ° C., an uncrosslinked fluororesin (Mw = 100,000) having an MF of 30 g / 10 min and a melting point of 245 ° C. is used. A fixing belt of Comparative Example 5 was obtained in the same manner as in Example 1 except that the resin and the uncrosslinked fluororesin were blended at a ratio of 50:50 and mixed with a simple kneader. No wrinkles were found on the surface of the obtained fixing belt.

(Comparative Example 6)
Instead of an uncrosslinked fluororesin having an MF of 5 g / 10 min and a melting point of 290 ° C., an uncrosslinked fluororesin (Mw = 1,020,000) having an MF of 3 g / 10 min and a melting point of 270 ° C. is used. A fixing belt of Comparative Example 6 was obtained in the same manner as in Example 1 except that the resin and the uncrosslinked fluororesin were blended at a ratio of 50:50 and mixed with a simple kneader. No wrinkles were found on the surface of the obtained fixing belt.

(Comparative Example 7)
Instead of an uncrosslinked fluororesin having an MF of 5 g / 10 min and a melting point of 290 ° C., an uncrosslinked fluororesin (Mw = 120,000) having an MF of 30 g / 10 min and a melting point of 270 ° C. is used. A fixing belt of Comparative Example 7 was obtained in the same manner as in Example 1 except that the resin and the uncrosslinked fluororesin were mixed at a ratio of 50:50 and mixed with a simple kneader. No wrinkles were found on the surface of the obtained fixing belt.

(Comparative Example 8)
Instead of an uncrosslinked fluororesin having an MF of 5 g / 10 min and a melting point of 290 ° C., an uncrosslinked fluororesin (Mw = 1,050,000) having an MF of 3 g / 10 min and a melting point of 300 ° C. is used. A fixing belt of Comparative Example 8 was obtained in the same manner as in Example 1 except that the resin and the uncrosslinked fluororesin were mixed at a ratio of 50:50 and mixed with a simple kneader. No wrinkles were found on the surface of the obtained fixing belt.

(Comparative Example 9)
Instead of an uncrosslinked fluororesin having an MF of 5 g / 10 min and a melting point of 290 ° C., an uncrosslinked fluororesin (Mw = 140,000) having an MF of 30 g / 10 min and a melting point of 300 ° C. is used. A fixing belt of Comparative Example 10 was obtained in the same manner as in Example 1 except that the resin and the uncrosslinked fluororesin were mixed at a ratio of 50:50 and mixed with a simple kneader. No wrinkles were found on the surface of the obtained fixing belt.

(Comparative Example 10)
Instead of an uncrosslinked fluororesin having an MF of 5 g / 10 min and a melting point of 290 ° C., an uncrosslinked fluororesin (Mw = 450,000) having an MF of 20 g / 10 min and a melting point of 310 ° C. is used. A fixing belt of Comparative Example 11 was obtained in the same manner as in Example 1 except that the resin and the uncrosslinked fluororesin were blended at a ratio of 50:50 and mixed with a simple kneader. No wrinkles were found on the surface of the obtained fixing belt.

(Comparative Example 11)
Instead of an uncrosslinked fluororesin having an MF of 5 g / 10 min and a melting point of 290 ° C., an uncrosslinked fluororesin (Mw = 1,080,000) having an MF of 3 g / 10 min and a melting point of 310 ° C. is used. A fixing belt of Comparative Example 11 was obtained in the same manner as in Example 1 except that the resin and the uncrosslinked fluororesin were mixed at a ratio of 70:30 and mixed with a simple kneader. No wrinkles were found on the surface of the obtained fixing belt.

(Comparative Example 12)
Other than using an uncrosslinked fluororesin (Mw = 100,000) having an MF of 30 g / 10 min and a melting point of 245 ° C. instead of the uncrosslinked fluororesin having an MF of 5 g / 10 min and a melting point of 290 ° C. Obtained a fixing belt of Comparative Example 12 in the same manner as in Example 1. No wrinkles were found on the surface of the obtained fixing belt.

(Comparative Example 13)
Other than using an uncrosslinked fluororesin (Mw = 1,080,000) having an MF of 3 g / 10 min and a melting point of 310 ° C. instead of the uncrosslinked fluororesin having an MF of 15 g / 10 min and a melting point of 270 ° C. Obtained a fixing belt of Comparative Example 13 in the same manner as in Example 7. No wrinkles were found on the surface of the obtained fixing belt.

(Comparative Example 14)
Other than using an uncrosslinked fluororesin (Mw = 160,000) having an MF of 30 g / 10 min and a melting point of 310 ° C. instead of the uncrosslinked fluororesin having an MF of 15 g / 10 min and a melting point of 270 ° C. Obtained a fixing belt of Comparative Example 14 in the same manner as in Example 7. No wrinkles were found on the surface of the obtained fixing belt.

(Comparative Example 15)
Other than using an uncrosslinked fluororesin (Mw = 1,020,000) having an MF of 3 g / 10 min and a melting point of 270 ° C. instead of the uncrosslinked fluororesin having an MF of 15 g / 10 min and a melting point of 270 ° C. Obtained a fixing belt of Comparative Example 15 in the same manner as in Example 7. No wrinkles were found on the surface of the obtained fixing belt.

(Comparative Example 16)
Other than using an uncrosslinked fluororesin (Mw = 1 million) having an MF of 3 g / 10 min and a melting point of 245 ° C. instead of the uncrosslinked fluororesin having an MF of 15 g / 10 min and a melting point of 270 ° C. Obtained a fixing belt of Comparative Example 16 in the same manner as in Example 9. No wrinkles were found on the surface of the obtained fixing belt.

(Comparative Example 17)
Other than using an uncrosslinked fluororesin (Mw = 410,000) having an MF of 20 g / 10 min and a melting point of 245 ° C. instead of the uncrosslinked fluororesin having an MF of 15 g / 10 min and a melting point of 270 ° C. A fixing belt of Comparative Example 17 was obtained in the same manner as in Example 9. No wrinkles were found on the surface of the obtained fixing belt.

(Comparative Example 18)
Other than using an uncrosslinked fluororesin (Mw = 100,000) having an MF of 30 g / 10 min and a melting point of 245 ° C., instead of the uncrosslinked fluororesin having an MF of 15 g / 10 min and a melting point of 270 ° C. A fixing belt of Comparative Example 18 was obtained in the same manner as in Example 9. No wrinkles were found on the surface of the obtained fixing belt.

(Comparative Example 19)
Other than using an uncrosslinked fluororesin (Mw = 1,020,000) having an MF of 3 g / 10 min and a melting point of 270 ° C. instead of the uncrosslinked fluororesin having an MF of 15 g / 10 min and a melting point of 270 ° C. A fixing belt of Comparative Example 19 was obtained in the same manner as in Example 9. No wrinkles were found on the surface of the obtained fixing belt.

(Comparative Example 20)
Other than using an uncrosslinked fluororesin (Mw = 120,000) having an MF of 30 g / 10 min and a melting point of 270 ° C. instead of the uncrosslinked fluororesin having an MF of 15 g / 10 min and a melting point of 270 ° C. Obtained a fixing belt of Comparative Example 20 in the same manner as in Example 9. No wrinkles were found on the surface of the obtained fixing belt.

(Comparative Example 21)
Other than using an uncrosslinked fluororesin (Mw = 450,000) having an MF of 20 g / 10 min and a melting point of 310 ° C. instead of the uncrosslinked fluororesin having an MF of 15 g / 10 min and a melting point of 270 ° C. A fixing belt of Comparative Example 21 was obtained in the same manner as in Example 9. No wrinkles were found on the surface of the obtained fixing belt.

(Comparative Example 22)
Other than using an uncrosslinked fluororesin (Mw = 160,000) having an MF of 30 g / 10 min and a melting point of 310 ° C. instead of the uncrosslinked fluororesin having an MF of 5 g / 10 min and a melting point of 290 ° C. Obtained a fixing belt of Comparative Example 22 in the same manner as in Example 9. No wrinkles were found on the surface of the obtained fixing belt.

(Comparative Example 23)
Other than using an uncrosslinked fluororesin (Mw = 1 million) having an MF of 3 g / 10 min and a melting point of 245 ° C. instead of the uncrosslinked fluororesin having an MF of 5 g / 10 min and a melting point of 290 ° C. Obtained a fixing belt of Comparative Example 23 in the same manner as in Example 1. No wrinkles were found on the surface of the obtained fixing belt.

(Comparative Example 24)
Other than using an uncrosslinked fluororesin (Mw = 410,000) having an MF of 20 g / 10 min and a melting point of 245 ° C. instead of the uncrosslinked fluororesin having an MF of 5 g / 10 min and a melting point of 290 ° C. Obtained a fixing belt of Comparative Example 24 in the same manner as in Example 1. No wrinkles were found on the surface of the obtained fixing belt.

(Comparative Example 25)
Other than using an uncrosslinked fluororesin (Mw = 1.20,000) having an MF of 3 g / 10 min and a melting point of 270 ° C. instead of the uncrosslinked fluororesin having an MF of 5 g / 10 min and a melting point of 290 ° C. A fixing belt of Comparative Example 25 was obtained in the same manner as in Example 1. No wrinkles were found on the surface of the obtained fixing belt.

(Comparative Example 26)
Other than using an uncrosslinked fluororesin (Mw = 120,000) having an MF of 30 g / 10 min and a melting point of 270 ° C. instead of the uncrosslinked fluororesin having an MF of 5 g / 10 min and a melting point of 290 ° C. Obtained a fixing belt of Comparative Example 26 in the same manner as in Example 1. No wrinkles were found on the surface of the obtained fixing belt.

(Comparative Example 27)
Other than using an uncrosslinked fluororesin (Mw = 1,080,000) having an MF of 3 g / 10 min and a melting point of 310 ° C. instead of the uncrosslinked fluororesin having an MF of 5 g / 10 min and a melting point of 290 ° C. Obtained a fixing belt of Comparative Example 27 in the same manner as in Example 1. No wrinkles were found on the surface of the obtained fixing belt.

(Comparative Example 28)
Other than using an uncrosslinked fluororesin (Mw = 450,000) having an MF of 20 g / 10 min and a melting point of 310 ° C. instead of the uncrosslinked fluororesin having an MF of 5 g / 10 min and a melting point of 290 ° C. Obtained a fixing belt of Comparative Example 28 in the same manner as in Example 1. No wrinkles were found on the surface of the obtained fixing belt.

(Comparative Example 29)
Other than using an uncrosslinked fluororesin (Mw = 160,000) having an MF of 30 g / 10 min and a melting point of 310 ° C. instead of the uncrosslinked fluororesin having an MF of 5 g / 10 min and a melting point of 290 ° C. Obtained a fixing belt of Comparative Example 29 in the same manner as in Example 1. No wrinkles were found on the surface of the obtained fixing belt.

  Using the fixing belts of Examples 1 to 14 and Comparative Examples 1 to 29, the flexibility of the release layer was evaluated from the toner density of the toner image and glossiness, and the smoothness and durability of the release layer were further evaluated. Evaluated.

  In order to evaluate the flexibility, smoothness and durability of the release layer, fixing of Examples 1 to 14 and Comparative Examples 1 to 29 was performed on a commercially available copier (trade name: MX-2700, manufactured by Sharp Corporation). Each belt was attached and the test was conducted as follows.

[Flexibility]
In the toner fixing property test, the image density and glossiness of the toner image on the copy paper after fixing were measured. From the evaluation results of the image density and glossiness, the toner fixing property was evaluated by ○, ×, and Δ, and this was evaluated as the flexibility.

(Image density)
For a monochrome image formed when the surface temperature of the heating roller is 180 ° C., the reflection density meter (trade name: RD918, manufactured by Macbeth Co., Ltd.) is used to measure the optical reflection density of the solid image portion, and this is used as the image density. It was. The toner adhesion amount of the solid image portion was 0.5 mg / cm ² .

The image density was evaluated according to the following evaluation criteria.
○: Good. The image density is 1.40 or higher.
Δ: No practical problem. The image density is 1.30 or more and less than 1.40.
X: Defect. The image density is less than 1.30.

(Glossiness)
For the measurement of glossiness in the solid image portion, a gloss meter (trade name: GLOSSMETER) is used.
UD, manufactured by Toyo Seiki Co., Ltd.), and reflected light of 75 ° when the angle of incident light was 75 ° was used.

The glossiness was evaluated according to the following evaluation criteria.
○: Good. Glossiness is 15 degrees or more.
Δ: No practical problem. Glossiness is 10 degrees or more and less than 15 degrees.
X: Defect. Glossiness is less than 10 degrees.

  Among the above measurement results, the image fixing result was preferentially considered and the toner fixing property was evaluated. The toner fixability evaluation criteria using the image density and glossiness evaluation results are as follows.

○: Good. The evaluation result of the image density and the glossiness is ○.
Δ: No problem in actual use. The image density or glossiness is Δ, and the image density is not “x”.
X: Defect. The evaluation result of image density has x.

[Smoothness]
The smoothness was evaluated using the surface roughness Ra of the release layer. The surface roughness Ra of the release layer was determined by directly measuring the release layer using Surfcoder SE3500 (Kosaka Laboratory Ltd.) and taking an average value of three times.

The evaluation criteria for smoothness are as follows.
○: Good. The surface roughness Ra is less than 0.3 μm.
Δ: No practical problem. The surface roughness Ra is not less than 0.3 μm and less than 0.4 μm.
X: Defect. The surface roughness Ra is 0.4 μm or more.

〔durability〕
Durability was evaluated by the number of sheets subjected to aging (paper passing test) until fixing failure occurred. Whether or not fixing failure has occurred is determined by observing the surface of the fixing member after every 100 (0.1k) aging and visually confirming the occurrence of scratches and cracks due to minute uneven patterns and friction. did.

The evaluation criteria for durability are as follows.
○: Good. Even if aging is performed for 20k sheets or more, there is no minute unevenness on the surface of the fixing member, and no scratch or crack is confirmed.
Δ: No practical problem. From 10k sheets to less than 20k sheets, minute irregularities are seen on the surface of the fixing member, but no scratches or cracks are confirmed.
X: Defect. With less than 10k sheets, minute irregularities are seen on the surface of the fixing member, and scratches and cracks are confirmed.

  The mixing ratio of the crosslinked fluororesin and the uncrosslinked fluororesin in Examples 1 to 14 and Comparative Examples 1 to 29, the MF and melting point of the uncrosslinked fluororesin, the thickness of the release layer, the surface roughness Ra of the release layer and the flexibility Table 1 shows the evaluation results of properties, smoothness and durability.

(Fixing roller production)
(Example 15)
Cross-linked fluororesin (trade name: XF1A, manufactured by Hitachi Cable Finetech Co., Ltd.) and uncrosslinked fluororesin (Mw = 930,000, MF = 5 g / 10 min, melting point 290 ° C.) cross-linked fluororesin: uncrosslinked fluororesin = 30 : It mixed with the simple kneader so that it might become a ratio of 70. A mirror-polished mold made of stainless steel (SUS304) having an inner diameter of 50 mm and a thickness of 3 mm was prepared. The mixed coating agent was applied as a release layer to the inner peripheral surface of the mold, and baked at 380 ° C. for 15 minutes. The thickness of the release layer after firing was 20 μm.

  Next, a metal hollow core metal core was prepared. After cooling the mold to room temperature, a hollow core metal core is inserted into the mold, and silicone rubber (trade name: KE-1241, manufactured by Shin-Etsu Silicon Co., Ltd.) is poured as an elastic layer between them. Baked at 250 ° C. for 30 minutes. The thickness of the elastic layer after firing was 2 mm. The JIS hardness of the fired elastic layer was A10 degrees. Silicone rubber was vulcanized to produce a heating roll having rubber elasticity.

  Subsequently, after cooling the mold to room temperature, the outer mold was removed to obtain the fixing roller of Example 15. No wrinkles were found on the surface of the obtained fixing roller.

(Example 16)
Other than using an uncrosslinked fluororesin (Mw = 300,000) having an MF of 25 g / 10 min and a melting point of 250 ° C., instead of the uncrosslinked fluororesin having an MF of 5 g / 10 min and a melting point of 290 ° C. Obtained a fixing roller of Example 16 in the same manner as Example 15. No wrinkles were found on the surface of the obtained fixing roller.

  The fixing rollers of Examples 15 to 28 and Comparative Examples 30 to 58 were obtained by changing the same points as in Examples 3 to 14 and Comparative Examples 1 to 12, respectively.

  Using the fixing rollers of Examples 15 to 28 and Comparative Examples 30 to 58, the flexibility, smoothness and durability of the release layer were evaluated in the same manner as in Examples 1 to 14 and Comparative Examples 1 to 12.

  The mixing ratio of the crosslinked fluororesin and the uncrosslinked fluororesin in Examples 15 to 28 and Comparative Examples 30 to 58, the MF and melting point of the uncrosslinked fluororesin, the thickness and surface roughness of the release layer, and the flexibility and smoothness Table 2 shows the evaluation results of durability.

  As is clear from Tables 1 and 2, the fixing belts of Examples 1 to 14 and the fixing rollers of Examples 15 to 28 according to the present invention have flexibility and smoothness of the release layer determined from evaluation of toner fixing properties. It can be seen that it is excellent in all aspects of durability.

  Examples 1-28 are excellent in the flexibility, smoothness, and durability of the release layer because the cross-linked fluororesin and uncrosslinked fluororesin are mixed before coating, so that they are sufficiently near the surface layer of the fixing member. This is because the toner fixability can be improved by being mixed and appropriately having flexibility and durability and being compatible with each other. Furthermore, since the outer surfaces of the release layers of Examples 1 to 11, 14, 15 to 25, and 28 are smooth, they are particularly excellent in smoothness and release properties. The releasability was evaluated by performing a fixing offset test in which the fixing temperature was changed by 10 ° C. between 140 and 200 ° C. In the fixing offset test, it was visually observed whether or not toner was fused to the surface of the fixing member. If no fixing offset occurred in all temperature ranges, the fixing member was considered to have excellent releasability. The fixing members of Examples 1 to 11, 14, 15 to 25, and 28 had no problem in releasability without causing fixing offset.

  The reason why the flexibility or durability is poor in Comparative Examples 1, 2, 13, and 14 is that the mixing balance between the crosslinked fluororesin and the uncrosslinked fluororesin becomes poor, and it becomes difficult to exhibit the performance.

  In Comparative Examples 3 to 10 and 15 to 24, the flexibility or durability of the release layer is deteriorated because at least one of the MF value and the melting point of the uncrosslinked fluororesin is not within the range defined in claim 1. This is because even when such an uncrosslinked fluororesin is mixed, a satisfactory image that satisfies toner fixing properties cannot be obtained, or durability as a fixing member is poor.

  From the results of Tables 1 and 2, the results shown in Tables 3 to 5 were obtained. Table 3 shows the MF and melting point of the uncrosslinked fluororesin when the ratio of crosslinked fluororesin: uncrosslinked fluororesin is 50:50, the release layer thickness is 20 μm, and the surface roughness is 0.3 μm or less. The evaluation results of the changed fixing members are summarized. Table 4 shows the MF and melting point of the uncrosslinked fluororesin when the ratio of crosslinked fluororesin: uncrosslinked fluororesin is 70:30, the release layer thickness is 20 μm, and the surface roughness is 0.3 μm or less. The evaluation results of the changed fixing members are summarized. Table 5 shows the MF and melting point of the uncrosslinked fluororesin when the ratio of crosslinked fluororesin: uncrosslinked fluororesin is 30:70, the release layer thickness is 20 μm, and the surface roughness is 0.3 μm or less. The evaluation results of the changed fixing members are summarized. From these tables, the release layer has a crosslinked fluororesin and an uncrosslinked fluororesin having a melting point of 250 to 300 ° C. and a melt flow index of 5 to 25 g / 10 min. It can be seen that a fixing member obtained by curing a coating material premixed at a ratio of 30 is excellent in durability, smoothness and flexibility.

1 is a cross-sectional view schematically showing a configuration of a fixing belt 100A according to a first embodiment of the present invention and a fixing device 6A including the fixing belt 100A. FIG. 2 is an enlarged cross-sectional view of section S101-S101 of fixing belt 100A shown in FIG. FIG. 3 is a cross-sectional view schematically showing a configuration of a fixing roller 100B according to the first embodiment of the present invention and a fixing device 6B in which the fixing roller 100B is incorporated. 1C is a cross-sectional view schematically showing a configuration of a first fixing roller 100C and a second fixing roller 100c, and a fixing device 6C incorporating the first fixing roller 100C and the second fixing roller 100c according to the first embodiment of the present invention. FIG. It is a block diagram regarding control of the member relevant to the heating of the fixing roller 6C. FIG. 2 is a cross-sectional view schematically showing a configuration of a fixing belt 100D according to a first embodiment of the present invention and a fixing device 6D in which the fixing belt 100D is incorporated. FIG. 6 is a block diagram regarding control of members related to heating of the fixing device 6D and driving of the fixing roller 50. 1 is a schematic diagram illustrating a configuration of an image forming apparatus 1 including a fixing device 6A of the present invention. It is the schematic which shows the structure of the image formation unit 10y.

Explanation of symbols

83 Elastic layer 84 Support layer 100A Fixing belt 102A Release layer

Claims (6)

A fixing member including a core material and a release layer formed on the surface of the core material,
The release layer is formed by curing a coating material in which a crosslinked fluororesin and an uncrosslinked fluororesin are mixed at a ratio of 30:70 to 70:30,
The uncrosslinked fluororesin has a melting point of 250 ° C. or higher and 300 ° C. or lower, and a melt flow index of 5 g / 10 min or higher and 25 g / 10 min or lower.   The fixing member according to claim 1, wherein the release layer has a thickness of 5 μm to 30 μm.   The fixing member according to claim 1, wherein a surface roughness Ra of the release layer is 0.3 μm or less.   A fixing device comprising the fixing member according to claim 1 incorporated therein. An image carrier on which a latent image is formed;
A latent image forming means for forming a latent image on the image carrier;
An image forming apparatus comprising the fixing device according to claim 4. A method for producing a fixing member comprising a core material and a release layer formed on the surface of the core material,
A coating material prepared by mixing a crosslinked fluororesin and an uncrosslinked fluororesin in a ratio of 30:70 to 70:30 is cured to form a release layer,
A method for producing a fixing member, comprising using an uncrosslinked fluororesin having a melting point of 250 ° C. or more and 300 ° C. or less and a melt flow index of 5 g / 10 min or more and 25 g / 10 min or less.

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